Merge github.com:grpc/grpc into better-profile

32 files changed, 1005 insertions, 721 deletions

diff --git a/src/core/client_config/subchannel.c b/src/core/client_config/subchannel.c
index 49c2cf9a19..b15a9033af 100644
--- a/src/core/client_config/subchannel.c
+++ b/src/core/client_config/subchannel.c
@@ -697,10 +697,25 @@ static double generate_uniform_random_number(grpc_subchannel *c) {
 
 /* Update backoff_delta and next_attempt in subchannel */
 static void update_reconnect_parameters(grpc_subchannel *c) {
+  size_t i;
   gpr_int32 backoff_delta_millis, jitter;
   gpr_int32 max_backoff_millis =
       GRPC_SUBCHANNEL_RECONNECT_MAX_BACKOFF_SECONDS * 1000;
   double jitter_range;
+
+  if (c->args) {
+    for (i = 0; i < c->args->num_args; i++) {
+      if (0 == strcmp(c->args->args[i].key,
+                      "grpc.testing.fixed_reconnect_backoff")) {
+        GPR_ASSERT(c->args->args[i].type == GRPC_ARG_INTEGER);
+        c->next_attempt = gpr_time_add(
+            gpr_now(GPR_CLOCK_MONOTONIC),
+            gpr_time_from_millis(c->args->args[i].value.integer, GPR_TIMESPAN));
+        return;
+      }
+    }
+  }
+
   backoff_delta_millis =
       (gpr_int32)(gpr_time_to_millis(c->backoff_delta) *
                   GRPC_SUBCHANNEL_RECONNECT_BACKOFF_MULTIPLIER);
diff --git a/src/core/client_config/subchannel.h b/src/core/client_config/subchannel.h
index 1fefa1888a..381b7689b8 100644
--- a/src/core/client_config/subchannel.h
+++ b/src/core/client_config/subchannel.h
@@ -77,10 +77,10 @@ void grpc_subchannel_call_unref(grpc_exec_ctx *exec_ctx,
 
 /** construct a subchannel call (possibly asynchronously).
  *
- * If the returned status is 1, the call will return immediately and \a target 
- * will point to a connected \a subchannel_call instance. Note that \a notify 
+ * If the returned status is 1, the call will return immediately and \a target
+ * will point to a connected \a subchannel_call instance. Note that \a notify
  * will \em not be invoked in this case.
- * Otherwise, if the returned status is 0, the subchannel call will be created 
+ * Otherwise, if the returned status is 0, the subchannel call will be created
  * asynchronously, invoking the \a notify callback upon completion. */
 int grpc_subchannel_create_call(grpc_exec_ctx *exec_ctx,
                                 grpc_subchannel *subchannel,
diff --git a/src/core/iomgr/pollset_windows.c b/src/core/iomgr/pollset_windows.c
index c3f310ee27..deb661548d 100644
--- a/src/core/iomgr/pollset_windows.c
+++ b/src/core/iomgr/pollset_windows.c
@@ -126,7 +126,8 @@ void grpc_pollset_destroy(grpc_pollset *pollset) {}
 
 void grpc_pollset_reset(grpc_pollset *pollset) {
   GPR_ASSERT(pollset->shutting_down);
-  GPR_ASSERT(!has_workers(&pollset->root_worker, GRPC_POLLSET_WORKER_LINK_POLLSET));
+  GPR_ASSERT(
+      !has_workers(&pollset->root_worker, GRPC_POLLSET_WORKER_LINK_POLLSET));
   pollset->shutting_down = 0;
   pollset->is_iocp_worker = 0;
   pollset->kicked_without_pollers = 0;
diff --git a/src/core/iomgr/tcp_server.h b/src/core/iomgr/tcp_server.h
index 882635f638..3df36174e7 100644
--- a/src/core/iomgr/tcp_server.h
+++ b/src/core/iomgr/tcp_server.h
@@ -39,6 +39,9 @@
 /* Forward decl of grpc_tcp_server */
 typedef struct grpc_tcp_server grpc_tcp_server;
 
+/* Forward decl of grpc_tcp_listener */
+typedef struct grpc_tcp_listener grpc_tcp_listener;
+
 /* Called for newly connected TCP connections. */
 typedef void (*grpc_tcp_server_cb)(grpc_exec_ctx *exec_ctx, void *arg,
                                    grpc_endpoint *ep);
@@ -51,19 +54,18 @@ void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *server,
                            grpc_pollset **pollsets, size_t pollset_count,
                            grpc_tcp_server_cb on_accept_cb, void *cb_arg);
 
-/* Add a port to the server, returning port number on success, or negative
-   on failure.
+/* Add a port to the server, returning the newly created listener on success,
+   or a null pointer on failure.
 
    The :: and 0.0.0.0 wildcard addresses are treated identically, accepting
    both IPv4 and IPv6 connections, but :: is the preferred style.  This usually
    creates one socket, but possibly two on systems which support IPv6,
-   but not dualstack sockets.
-
-   For raw access to the underlying sockets, see grpc_tcp_server_get_fd(). */
+   but not dualstack sockets. */
 /* TODO(ctiller): deprecate this, and make grpc_tcp_server_add_ports to handle
                   all of the multiple socket port matching logic in one place */
-int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
-                             size_t addr_len);
+grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
+                                            const void *addr,
+                                            size_t addr_len);
 
 /* Returns the file descriptor of the Nth listening socket on this server,
    or -1 if the index is out of bounds.
@@ -75,4 +77,8 @@ int grpc_tcp_server_get_fd(grpc_tcp_server *s, unsigned index);
 void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *server,
                              grpc_closure *closure);
 
+int grpc_tcp_listener_get_port(grpc_tcp_listener *listener);
+void grpc_tcp_listener_ref(grpc_tcp_listener *listener);
+void grpc_tcp_listener_unref(grpc_tcp_listener *listener);
+
 #endif /* GRPC_INTERNAL_CORE_IOMGR_TCP_SERVER_H */
diff --git a/src/core/iomgr/tcp_server_posix.c b/src/core/iomgr/tcp_server_posix.c
index 99c76dcbe9..1439dfcd6e 100644
--- a/src/core/iomgr/tcp_server_posix.c
+++ b/src/core/iomgr/tcp_server_posix.c
@@ -67,14 +67,13 @@
 #include <grpc/support/sync.h>
 #include <grpc/support/time.h>
 
-#define INIT_PORT_CAP 2
 #define MIN_SAFE_ACCEPT_QUEUE_SIZE 100
 
 static gpr_once s_init_max_accept_queue_size;
 static int s_max_accept_queue_size;
 
 /* one listening port */
-typedef struct {
+struct grpc_tcp_listener {
   int fd;
   grpc_fd *emfd;
   grpc_tcp_server *server;
@@ -84,9 +83,18 @@ typedef struct {
     struct sockaddr_un un;
   } addr;
   size_t addr_len;
+  int port;
   grpc_closure read_closure;
   grpc_closure destroyed_closure;
-} server_port;
+  gpr_refcount refs;
+  struct grpc_tcp_listener *next;
+  /* When we add a listener, more than one can be created, mainly because of
+     IPv6. A sibling will still be in the normal list, but will be flagged
+     as such. Any action, such as ref or unref, will affect all of the
+     siblings in the list. */
+  struct grpc_tcp_listener *sibling;
+  int is_sibling;
+};
 
 static void unlink_if_unix_domain_socket(const struct sockaddr_un *un) {
   struct stat st;
@@ -112,10 +120,9 @@ struct grpc_tcp_server {
   /* is this server shutting down? (boolean) */
   int shutdown;
 
-  /* all listening ports */
-  server_port *ports;
-  size_t nports;
-  size_t port_capacity;
+  /* linked list of server ports */
+  grpc_tcp_listener *head;
+  unsigned nports;
 
   /* shutdown callback */
   grpc_closure *shutdown_complete;
@@ -134,9 +141,8 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
   s->shutdown = 0;
   s->on_accept_cb = NULL;
   s->on_accept_cb_arg = NULL;
-  s->ports = gpr_malloc(sizeof(server_port) * INIT_PORT_CAP);
+  s->head = NULL;
   s->nports = 0;
-  s->port_capacity = INIT_PORT_CAP;
   return s;
 }
 
@@ -145,7 +151,12 @@ static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
 
   gpr_mu_destroy(&s->mu);
 
-  gpr_free(s->ports);
+  while (s->head) {
+    grpc_tcp_listener *sp = s->head;
+    s->head = sp->next;
+    grpc_tcp_listener_unref(sp);
+  }
+
   gpr_free(s);
 }
 
@@ -166,8 +177,6 @@ static void destroyed_port(grpc_exec_ctx *exec_ctx, void *server, int success) {
    events will be received on them - at this point it's safe to destroy
    things */
 static void deactivated_all_ports(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
-  size_t i;
-
   /* delete ALL the things */
   gpr_mu_lock(&s->mu);
 
@@ -176,9 +185,9 @@ static void deactivated_all_ports(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
     return;
   }
 
-  if (s->nports) {
-    for (i = 0; i < s->nports; i++) {
-      server_port *sp = &s->ports[i];
+  if (s->head) {
+    grpc_tcp_listener *sp;
+    for (sp = s->head; sp; sp = sp->next) {
       if (sp->addr.sockaddr.sa_family == AF_UNIX) {
         unlink_if_unix_domain_socket(&sp->addr.un);
       }
@@ -196,7 +205,6 @@ static void deactivated_all_ports(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
 
 void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                              grpc_closure *closure) {
-  size_t i;
   gpr_mu_lock(&s->mu);
 
   GPR_ASSERT(!s->shutdown);
@@ -206,8 +214,9 @@ void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
 
   /* shutdown all fd's */
   if (s->active_ports) {
-    for (i = 0; i < s->nports; i++) {
-      grpc_fd_shutdown(exec_ctx, s->ports[i].emfd);
+    grpc_tcp_listener *sp;
+    for (sp = s->head; sp; sp = sp->next) {
+      grpc_fd_shutdown(exec_ctx, sp->emfd);
     }
     gpr_mu_unlock(&s->mu);
   } else {
@@ -298,7 +307,7 @@ error:
 
 /* event manager callback when reads are ready */
 static void on_read(grpc_exec_ctx *exec_ctx, void *arg, int success) {
-  server_port *sp = arg;
+  grpc_tcp_listener *sp = arg;
   grpc_fd *fdobj;
   size_t i;
 
@@ -364,9 +373,10 @@ error:
   }
 }
 
-static int add_socket_to_server(grpc_tcp_server *s, int fd,
-                                const struct sockaddr *addr, size_t addr_len) {
-  server_port *sp;
+static grpc_tcp_listener *add_socket_to_server(grpc_tcp_server *s, int fd,
+                                         const struct sockaddr *addr,
+                                         size_t addr_len) {
+  grpc_tcp_listener *sp = NULL;
   int port;
   char *addr_str;
   char *name;
@@ -376,32 +386,35 @@ static int add_socket_to_server(grpc_tcp_server *s, int fd,
     grpc_sockaddr_to_string(&addr_str, (struct sockaddr *)&addr, 1);
     gpr_asprintf(&name, "tcp-server-listener:%s", addr_str);
     gpr_mu_lock(&s->mu);
+    s->nports++;
     GPR_ASSERT(!s->on_accept_cb && "must add ports before starting server");
-    /* append it to the list under a lock */
-    if (s->nports == s->port_capacity) {
-      s->port_capacity *= 2;
-      s->ports = gpr_realloc(s->ports, sizeof(server_port) * s->port_capacity);
-    }
-    sp = &s->ports[s->nports++];
+    sp = gpr_malloc(sizeof(grpc_tcp_listener));
+    sp->next = s->head;
+    s->head = sp;
     sp->server = s;
     sp->fd = fd;
     sp->emfd = grpc_fd_create(fd, name);
     memcpy(sp->addr.untyped, addr, addr_len);
     sp->addr_len = addr_len;
+    sp->port = port;
+    sp->is_sibling = 0;
+    sp->sibling = NULL;
+    gpr_ref_init(&sp->refs, 1);
     GPR_ASSERT(sp->emfd);
     gpr_mu_unlock(&s->mu);
     gpr_free(addr_str);
     gpr_free(name);
   }
 
-  return port;
+  return sp;
 }
 
-int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
-                             size_t addr_len) {
-  int allocated_port1 = -1;
-  int allocated_port2 = -1;
-  unsigned i;
+grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
+                                            const void *addr,
+                                            size_t addr_len) {
+  int allocated_port = -1;
+  grpc_tcp_listener *sp;
+  grpc_tcp_listener *sp2 = NULL;
   int fd;
   grpc_dualstack_mode dsmode;
   struct sockaddr_in6 addr6_v4mapped;
@@ -420,9 +433,9 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
   /* Check if this is a wildcard port, and if so, try to keep the port the same
      as some previously created listener. */
   if (grpc_sockaddr_get_port(addr) == 0) {
-    for (i = 0; i < s->nports; i++) {
+    for (sp = s->head; sp; sp = sp->next) {
       sockname_len = sizeof(sockname_temp);
-      if (0 == getsockname(s->ports[i].fd, (struct sockaddr *)&sockname_temp,
+      if (0 == getsockname(sp->fd, (struct sockaddr *)&sockname_temp,
                            &sockname_len)) {
         port = grpc_sockaddr_get_port((struct sockaddr *)&sockname_temp);
         if (port > 0) {
@@ -436,6 +449,8 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     }
   }
 
+  sp = NULL;
+
   if (grpc_sockaddr_to_v4mapped(addr, &addr6_v4mapped)) {
     addr = (const struct sockaddr *)&addr6_v4mapped;
     addr_len = sizeof(addr6_v4mapped);
@@ -449,14 +464,16 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     addr = (struct sockaddr *)&wild6;
     addr_len = sizeof(wild6);
     fd = grpc_create_dualstack_socket(addr, SOCK_STREAM, 0, &dsmode);
-    allocated_port1 = add_socket_to_server(s, fd, addr, addr_len);
+    sp = add_socket_to_server(s, fd, addr, addr_len);
+    allocated_port = sp->port;
     if (fd >= 0 && dsmode == GRPC_DSMODE_DUALSTACK) {
       goto done;
     }
 
     /* If we didn't get a dualstack socket, also listen on 0.0.0.0. */
-    if (port == 0 && allocated_port1 > 0) {
-      grpc_sockaddr_set_port((struct sockaddr *)&wild4, allocated_port1);
+    if (port == 0 && allocated_port > 0) {
+      grpc_sockaddr_set_port((struct sockaddr *)&wild4, allocated_port);
+      sp2 = sp;
     }
     addr = (struct sockaddr *)&wild4;
     addr_len = sizeof(wild4);
@@ -471,22 +488,31 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     addr = (struct sockaddr *)&addr4_copy;
     addr_len = sizeof(addr4_copy);
   }
-  allocated_port2 = add_socket_to_server(s, fd, addr, addr_len);
+  sp = add_socket_to_server(s, fd, addr, addr_len);
+  sp->sibling = sp2;
+  if (sp2) sp2->is_sibling = 1;
 
 done:
   gpr_free(allocated_addr);
-  return allocated_port1 >= 0 ? allocated_port1 : allocated_port2;
+  return sp;
 }
 
 int grpc_tcp_server_get_fd(grpc_tcp_server *s, unsigned port_index) {
-  return (port_index < s->nports) ? s->ports[port_index].fd : -1;
+  grpc_tcp_listener *sp;
+  for (sp = s->head; sp && port_index != 0; sp = sp->next, port_index--);
+  if (port_index == 0 && sp) {
+    return sp->fd;
+  } else {
+    return -1;
+  }
 }
 
 void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                            grpc_pollset **pollsets, size_t pollset_count,
                            grpc_tcp_server_cb on_accept_cb,
                            void *on_accept_cb_arg) {
-  size_t i, j;
+  size_t i;
+  grpc_tcp_listener *sp;
   GPR_ASSERT(on_accept_cb);
   gpr_mu_lock(&s->mu);
   GPR_ASSERT(!s->on_accept_cb);
@@ -495,17 +521,41 @@ void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
   s->on_accept_cb_arg = on_accept_cb_arg;
   s->pollsets = pollsets;
   s->pollset_count = pollset_count;
-  for (i = 0; i < s->nports; i++) {
-    for (j = 0; j < pollset_count; j++) {
-      grpc_pollset_add_fd(exec_ctx, pollsets[j], s->ports[i].emfd);
+  for (sp = s->head; sp; sp = sp->next) {
+    for (i = 0; i < pollset_count; i++) {
+      grpc_pollset_add_fd(exec_ctx, pollsets[i], sp->emfd);
     }
-    s->ports[i].read_closure.cb = on_read;
-    s->ports[i].read_closure.cb_arg = &s->ports[i];
-    grpc_fd_notify_on_read(exec_ctx, s->ports[i].emfd,
-                           &s->ports[i].read_closure);
+    sp->read_closure.cb = on_read;
+    sp->read_closure.cb_arg = sp;
+    grpc_fd_notify_on_read(exec_ctx, sp->emfd,
+                           &sp->read_closure);
     s->active_ports++;
   }
   gpr_mu_unlock(&s->mu);
 }
 
+int grpc_tcp_listener_get_port(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  return sp->port;
+}
+
+void grpc_tcp_listener_ref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  gpr_ref(&sp->refs);
+}
+
+void grpc_tcp_listener_unref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  if (sp->is_sibling) return;
+  if (gpr_unref(&sp->refs)) {
+    grpc_tcp_listener *sibling = sp->sibling;
+    while (sibling) {
+      sp = sibling;
+      sibling = sp->sibling;
+      gpr_free(sp);
+    }
+    gpr_free(listener);
+  }
+}
+
 #endif
diff --git a/src/core/iomgr/tcp_server_windows.c b/src/core/iomgr/tcp_server_windows.c
index 3fea8b5b35..e4a1d7f498 100644
--- a/src/core/iomgr/tcp_server_windows.c
+++ b/src/core/iomgr/tcp_server_windows.c
@@ -35,7 +35,8 @@
 
 #ifdef GPR_WINSOCK_SOCKET
 
-#define _GNU_SOURCE
+#include <io.h>
+
 #include "src/core/iomgr/sockaddr_utils.h"
 
 #include <grpc/support/alloc.h>
@@ -51,25 +52,29 @@
 #include "src/core/iomgr/tcp_server.h"
 #include "src/core/iomgr/tcp_windows.h"
 
-#define INIT_PORT_CAP 2
 #define MIN_SAFE_ACCEPT_QUEUE_SIZE 100
 
 /* one listening port */
-typedef struct server_port {
+struct grpc_tcp_listener {
   /* This seemingly magic number comes from AcceptEx's documentation. each
      address buffer needs to have at least 16 more bytes at their end. */
   gpr_uint8 addresses[(sizeof(struct sockaddr_in6) + 16) * 2];
   /* This will hold the socket for the next accept. */
   SOCKET new_socket;
-  /* The listener winsocked. */
+  /* The listener winsocket. */
   grpc_winsocket *socket;
+  /* The actual TCP port number. */
+  int port;
   grpc_tcp_server *server;
   /* The cached AcceptEx for that port. */
   LPFN_ACCEPTEX AcceptEx;
   int shutting_down;
   /* closure for socket notification of accept being ready */
   grpc_closure on_accept;
-} server_port;
+  gpr_refcount refs;
+  /* linked list */
+  struct grpc_tcp_listener *next;
+};
 
 /* the overall server */
 struct grpc_tcp_server {
@@ -82,10 +87,8 @@ struct grpc_tcp_server {
   /* active port count: how many ports are actually still listening */
   int active_ports;
 
-  /* all listening ports */
-  server_port *ports;
-  size_t nports;
-  size_t port_capacity;
+  /* linked list of server ports */
+  grpc_tcp_listener *head;
 
   /* shutdown callback */
   grpc_closure *shutdown_complete;
@@ -99,9 +102,7 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
   s->active_ports = 0;
   s->on_accept_cb = NULL;
   s->on_accept_cb_arg = NULL;
-  s->ports = gpr_malloc(sizeof(server_port) * INIT_PORT_CAP);
-  s->nports = 0;
-  s->port_capacity = INIT_PORT_CAP;
+  s->head = NULL;
   s->shutdown_complete = NULL;
   return s;
 }
@@ -109,26 +110,26 @@ grpc_tcp_server *grpc_tcp_server_create(void) {
 static void dont_care_about_shutdown_completion(void *arg) {}
 
 static void finish_shutdown(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
-  size_t i;
-
   grpc_exec_ctx_enqueue(exec_ctx, s->shutdown_complete, 1);
 
   /* Now that the accepts have been aborted, we can destroy the sockets.
      The IOCP won't get notified on these, so we can flag them as already
      closed by the system. */
-  for (i = 0; i < s->nports; i++) {
-    server_port *sp = &s->ports[i];
+  while (s->head) {
+    grpc_tcp_listener *sp = s->head;
+    s->head = sp->next;
+    sp->next = NULL;
     grpc_winsocket_destroy(sp->socket);
+    grpc_tcp_listener_unref(sp);
   }
-  gpr_free(s->ports);
   gpr_free(s);
 }
 
 /* Public function. Stops and destroys a grpc_tcp_server. */
 void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                              grpc_closure *shutdown_complete) {
-  size_t i;
   int immediately_done = 0;
+  grpc_tcp_listener *sp;
   gpr_mu_lock(&s->mu);
 
   s->shutdown_complete = shutdown_complete;
@@ -138,8 +139,7 @@ void grpc_tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
   if (s->active_ports == 0) {
     immediately_done = 1;
   }
-  for (i = 0; i < s->nports; i++) {
-    server_port *sp = &s->ports[i];
+  for (sp = s->head; sp; sp = sp->next) {
     sp->shutting_down = 1;
     grpc_winsocket_shutdown(sp->socket);
   }
@@ -199,7 +199,7 @@ error:
 }
 
 static void decrement_active_ports_and_notify(grpc_exec_ctx *exec_ctx,
-                                              server_port *sp) {
+                                              grpc_tcp_listener *sp) {
   int notify = 0;
   sp->shutting_down = 0;
   gpr_mu_lock(&sp->server->mu);
@@ -216,7 +216,7 @@ static void decrement_active_ports_and_notify(grpc_exec_ctx *exec_ctx,
 
 /* In order to do an async accept, we need to create a socket first which
    will be the one assigned to the new incoming connection. */
-static void start_accept(grpc_exec_ctx *exec_ctx, server_port *port) {
+static void start_accept(grpc_exec_ctx *exec_ctx, grpc_tcp_listener *port) {
   SOCKET sock = INVALID_SOCKET;
   char *message;
   char *utf8_message;
@@ -276,7 +276,7 @@ failure:
 
 /* Event manager callback when reads are ready. */
 static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, int from_iocp) {
-  server_port *sp = arg;
+  grpc_tcp_listener *sp = arg;
   SOCKET sock = sp->new_socket;
   grpc_winsocket_callback_info *info = &sp->socket->read_info;
   grpc_endpoint *ep = NULL;
@@ -351,16 +351,17 @@ static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, int from_iocp) {
   start_accept(exec_ctx, sp);
 }
 
-static int add_socket_to_server(grpc_tcp_server *s, SOCKET sock,
-                                const struct sockaddr *addr, size_t addr_len) {
-  server_port *sp;
+static grpc_tcp_listener *add_socket_to_server(grpc_tcp_server *s, SOCKET sock,
+                                         const struct sockaddr *addr,
+                                         size_t addr_len) {
+  grpc_tcp_listener *sp = NULL;
   int port;
   int status;
   GUID guid = WSAID_ACCEPTEX;
   DWORD ioctl_num_bytes;
   LPFN_ACCEPTEX AcceptEx;
 
-  if (sock == INVALID_SOCKET) return -1;
+  if (sock == INVALID_SOCKET) return NULL;
 
   /* We need to grab the AcceptEx pointer for that port, as it may be
      interface-dependent. We'll cache it to avoid doing that again. */
@@ -373,37 +374,35 @@ static int add_socket_to_server(grpc_tcp_server *s, SOCKET sock,
     gpr_log(GPR_ERROR, "on_connect error: %s", utf8_message);
     gpr_free(utf8_message);
     closesocket(sock);
-    return -1;
+    return NULL;
   }
 
   port = prepare_socket(sock, addr, addr_len);
   if (port >= 0) {
     gpr_mu_lock(&s->mu);
     GPR_ASSERT(!s->on_accept_cb && "must add ports before starting server");
-    /* append it to the list under a lock */
-    if (s->nports == s->port_capacity) {
-      /* too many ports, and we need to store their address in a closure */
-      /* TODO(ctiller): make server_port a linked list */
-      abort();
-    }
-    sp = &s->ports[s->nports++];
+    sp = gpr_malloc(sizeof(grpc_tcp_listener));
+    sp->next = s->head;
+    s->head = sp;
     sp->server = s;
     sp->socket = grpc_winsocket_create(sock, "listener");
     sp->shutting_down = 0;
     sp->AcceptEx = AcceptEx;
     sp->new_socket = INVALID_SOCKET;
+    sp->port = port;
+    gpr_ref_init(&sp->refs, 1);
     grpc_closure_init(&sp->on_accept, on_accept, sp);
     GPR_ASSERT(sp->socket);
     gpr_mu_unlock(&s->mu);
   }
 
-  return port;
+  return sp;
 }
 
-int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
-                             size_t addr_len) {
-  int allocated_port = -1;
-  unsigned i;
+grpc_tcp_listener *grpc_tcp_server_add_port(grpc_tcp_server *s,
+                                            const void *addr,
+                                            size_t addr_len) {
+  grpc_tcp_listener *sp;
   SOCKET sock;
   struct sockaddr_in6 addr6_v4mapped;
   struct sockaddr_in6 wildcard;
@@ -415,9 +414,9 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
   /* Check if this is a wildcard port, and if so, try to keep the port the same
      as some previously created listener. */
   if (grpc_sockaddr_get_port(addr) == 0) {
-    for (i = 0; i < s->nports; i++) {
+    for (sp = s->head; sp; sp = sp->next) {
       sockname_len = sizeof(sockname_temp);
-      if (0 == getsockname(s->ports[i].socket->socket,
+      if (0 == getsockname(sp->socket->socket,
                            (struct sockaddr *)&sockname_temp, &sockname_len)) {
         port = grpc_sockaddr_get_port((struct sockaddr *)&sockname_temp);
         if (port > 0) {
@@ -452,33 +451,55 @@ int grpc_tcp_server_add_port(grpc_tcp_server *s, const void *addr,
     gpr_free(utf8_message);
   }
 
-  allocated_port = add_socket_to_server(s, sock, addr, addr_len);
+  sp = add_socket_to_server(s, sock, addr, addr_len);
   gpr_free(allocated_addr);
 
-  return allocated_port;
+  return sp;
 }
 
-SOCKET
-grpc_tcp_server_get_socket(grpc_tcp_server *s, unsigned index) {
-  return (index < s->nports) ? s->ports[index].socket->socket : INVALID_SOCKET;
+int grpc_tcp_server_get_fd(grpc_tcp_server *s, unsigned port_index) {
+  grpc_tcp_listener *sp;
+  for (sp = s->head; sp && port_index != 0; sp = sp->next, port_index--);
+  if (port_index == 0 && sp) {
+    return _open_osfhandle(sp->socket->socket, 0);
+  } else {
+    return -1;
+  }
 }
 
 void grpc_tcp_server_start(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s,
                            grpc_pollset **pollset, size_t pollset_count,
                            grpc_tcp_server_cb on_accept_cb,
                            void *on_accept_cb_arg) {
-  size_t i;
+  grpc_tcp_listener *sp;
   GPR_ASSERT(on_accept_cb);
   gpr_mu_lock(&s->mu);
   GPR_ASSERT(!s->on_accept_cb);
   GPR_ASSERT(s->active_ports == 0);
   s->on_accept_cb = on_accept_cb;
   s->on_accept_cb_arg = on_accept_cb_arg;
-  for (i = 0; i < s->nports; i++) {
-    start_accept(exec_ctx, s->ports + i);
+  for (sp = s->head; sp; sp = sp->next) {
+    start_accept(exec_ctx, sp);
     s->active_ports++;
   }
   gpr_mu_unlock(&s->mu);
 }
 
+int grpc_tcp_listener_get_port(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  return sp->port;
+}
+
+void grpc_tcp_listener_ref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  gpr_ref(&sp->refs);
+}
+
+void grpc_tcp_listener_unref(grpc_tcp_listener *listener) {
+  grpc_tcp_listener *sp = listener;
+  if (gpr_unref(&sp->refs)) {
+    gpr_free(listener);
+  }
+}
+
 #endif /* GPR_WINSOCK_SOCKET */
diff --git a/src/core/security/client_auth_filter.c b/src/core/security/client_auth_filter.c
index c780b65873..be2522a7a0 100644
--- a/src/core/security/client_auth_filter.c
+++ b/src/core/security/client_auth_filter.c
@@ -50,7 +50,7 @@
 
 /* We can have a per-call credentials. */
 typedef struct {
-  grpc_credentials *creds;
+  grpc_call_credentials *creds;
   grpc_mdstr *host;
   grpc_mdstr *method;
   /* pollset bound to this call; if we need to make external
@@ -143,39 +143,35 @@ static void send_security_metadata(grpc_exec_ctx *exec_ctx,
   channel_data *chand = elem->channel_data;
   grpc_client_security_context *ctx =
       (grpc_client_security_context *)op->context[GRPC_CONTEXT_SECURITY].value;
-  grpc_credentials *channel_creds =
+  grpc_call_credentials *channel_call_creds =
       chand->security_connector->request_metadata_creds;
-  int channel_creds_has_md =
-      (channel_creds != NULL) &&
-      grpc_credentials_has_request_metadata(channel_creds);
-  int call_creds_has_md = (ctx != NULL) && (ctx->creds != NULL) &&
-                          grpc_credentials_has_request_metadata(ctx->creds);
+  int call_creds_has_md = (ctx != NULL) && (ctx->creds != NULL);
 
-  if (!channel_creds_has_md && !call_creds_has_md) {
+  if (channel_call_creds == NULL && !call_creds_has_md) {
     /* Skip sending metadata altogether. */
     grpc_call_next_op(exec_ctx, elem, op);
     return;
   }
 
-  if (channel_creds_has_md && call_creds_has_md) {
-    calld->creds =
-        grpc_composite_credentials_create(channel_creds, ctx->creds, NULL);
+  if (channel_call_creds != NULL && call_creds_has_md) {
+    calld->creds = grpc_composite_call_credentials_create(channel_call_creds,
+                                                          ctx->creds, NULL);
     if (calld->creds == NULL) {
       bubble_up_error(exec_ctx, elem, GRPC_STATUS_INVALID_ARGUMENT,
                       "Incompatible credentials set on channel and call.");
       return;
     }
   } else {
-    calld->creds =
-        grpc_credentials_ref(call_creds_has_md ? ctx->creds : channel_creds);
+    calld->creds = grpc_call_credentials_ref(
+        call_creds_has_md ? ctx->creds : channel_call_creds);
   }
 
   build_service_url(chand->security_connector->base.url_scheme, calld);
   calld->op = *op; /* Copy op (originates from the caller's stack). */
   GPR_ASSERT(calld->pollset);
-  grpc_credentials_get_request_metadata(exec_ctx, calld->creds, calld->pollset,
-                                        calld->service_url,
-                                        on_credentials_metadata, elem);
+  grpc_call_credentials_get_request_metadata(exec_ctx, calld->creds,
+                                             calld->pollset, calld->service_url,
+                                             on_credentials_metadata, elem);
 }
 
 static void on_host_checked(grpc_exec_ctx *exec_ctx, void *user_data,
@@ -282,7 +278,7 @@ static void set_pollset(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx,
                               grpc_call_element *elem) {
   call_data *calld = elem->call_data;
-  grpc_credentials_unref(calld->creds);
+  grpc_call_credentials_unref(calld->creds);
   if (calld->host != NULL) {
     GRPC_MDSTR_UNREF(calld->host);
   }
diff --git a/src/core/security/credentials.c b/src/core/security/credentials.c
index 2a8ffae5d7..f7a2e73785 100644
--- a/src/core/security/credentials.c
+++ b/src/core/security/credentials.c
@@ -54,18 +54,18 @@
 /* -- Common. -- */
 
 struct grpc_credentials_metadata_request {
-  grpc_credentials *creds;
+  grpc_call_credentials *creds;
   grpc_credentials_metadata_cb cb;
   void *user_data;
 };
 
 static grpc_credentials_metadata_request *
-grpc_credentials_metadata_request_create(grpc_credentials *creds,
+grpc_credentials_metadata_request_create(grpc_call_credentials *creds,
                                          grpc_credentials_metadata_cb cb,
                                          void *user_data) {
   grpc_credentials_metadata_request *r =
       gpr_malloc(sizeof(grpc_credentials_metadata_request));
-  r->creds = grpc_credentials_ref(creds);
+  r->creds = grpc_call_credentials_ref(creds);
   r->cb = cb;
   r->user_data = user_data;
   return r;
@@ -73,44 +73,56 @@ grpc_credentials_metadata_request_create(grpc_credentials *creds,
 
 static void grpc_credentials_metadata_request_destroy(
     grpc_credentials_metadata_request *r) {
-  grpc_credentials_unref(r->creds);
+  grpc_call_credentials_unref(r->creds);
   gpr_free(r);
 }
 
-grpc_credentials *grpc_credentials_ref(grpc_credentials *creds) {
+grpc_channel_credentials *grpc_channel_credentials_ref(
+    grpc_channel_credentials *creds) {
   if (creds == NULL) return NULL;
   gpr_ref(&creds->refcount);
   return creds;
 }
 
-void grpc_credentials_unref(grpc_credentials *creds) {
+void grpc_channel_credentials_unref(grpc_channel_credentials *creds) {
   if (creds == NULL) return;
   if (gpr_unref(&creds->refcount)) {
-    creds->vtable->destruct(creds);
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
     gpr_free(creds);
   }
 }
 
-void grpc_credentials_release(grpc_credentials *creds) {
-  GRPC_API_TRACE("grpc_credentials_release(creds=%p)", 1, (creds));
-  grpc_credentials_unref(creds);
+void grpc_channel_credentials_release(grpc_channel_credentials *creds) {
+  GRPC_API_TRACE("grpc_channel_credentials_release(creds=%p)", 1, (creds));
+  grpc_channel_credentials_unref(creds);
 }
 
-int grpc_credentials_has_request_metadata(grpc_credentials *creds) {
-  if (creds == NULL) return 0;
-  return creds->vtable->has_request_metadata(creds);
+grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds) {
+  if (creds == NULL) return NULL;
+  gpr_ref(&creds->refcount);
+  return creds;
+}
+
+void grpc_call_credentials_unref(grpc_call_credentials *creds) {
+  if (creds == NULL) return;
+  if (gpr_unref(&creds->refcount)) {
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
+    gpr_free(creds);
+  }
 }
 
-int grpc_credentials_has_request_metadata_only(grpc_credentials *creds) {
-  if (creds == NULL) return 0;
-  return creds->vtable->has_request_metadata_only(creds);
+void grpc_call_credentials_release(grpc_call_credentials *creds) {
+  GRPC_API_TRACE("grpc_call_credentials_release(creds=%p)", 1, (creds));
+  grpc_call_credentials_unref(creds);
 }
 
-void grpc_credentials_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
-  if (creds == NULL || !grpc_credentials_has_request_metadata(creds) ||
-      creds->vtable->get_request_metadata == NULL) {
+void grpc_call_credentials_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                                grpc_call_credentials *creds,
+                                                grpc_pollset *pollset,
+                                                const char *service_url,
+                                                grpc_credentials_metadata_cb cb,
+                                                void *user_data) {
+  if (creds == NULL || creds->vtable->get_request_metadata == NULL) {
     if (cb != NULL) {
       cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK);
     }
@@ -120,19 +132,17 @@ void grpc_credentials_get_request_metadata(
                                       user_data);
 }
 
-grpc_security_status grpc_credentials_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+grpc_security_status grpc_channel_credentials_create_security_connector(
+    grpc_channel_credentials *channel_creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args) {
   *new_args = NULL;
-  if (creds == NULL || creds->vtable->create_security_connector == NULL ||
-      grpc_credentials_has_request_metadata_only(creds)) {
-    gpr_log(GPR_ERROR,
-            "Invalid credentials for creating a security connector.");
+  if (channel_creds == NULL) {
     return GRPC_SECURITY_ERROR;
   }
-  return creds->vtable->create_security_connector(
-      creds, target, args, request_metadata_creds, sc, new_args);
+  GPR_ASSERT(channel_creds->vtable->create_security_connector != NULL);
+  return channel_creds->vtable->create_security_connector(
+      channel_creds, NULL, target, args, sc, new_args);
 }
 
 grpc_server_credentials *grpc_server_credentials_ref(
@@ -145,7 +155,7 @@ grpc_server_credentials *grpc_server_credentials_ref(
 void grpc_server_credentials_unref(grpc_server_credentials *creds) {
   if (creds == NULL) return;
   if (gpr_unref(&creds->refcount)) {
-    creds->vtable->destruct(creds);
+    if (creds->vtable->destruct != NULL) creds->vtable->destruct(creds);
     if (creds->processor.destroy != NULL && creds->processor.state != NULL) {
       creds->processor.destroy(creds->processor.state);
     }
@@ -224,7 +234,7 @@ grpc_server_credentials *grpc_find_server_credentials_in_args(
 
 /* -- Ssl credentials. -- */
 
-static void ssl_destruct(grpc_credentials *creds) {
+static void ssl_destruct(grpc_channel_credentials *creds) {
   grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
   if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
   if (c->config.pem_private_key != NULL) gpr_free(c->config.pem_private_key);
@@ -253,15 +263,9 @@ static void ssl_server_destruct(grpc_server_credentials *creds) {
   if (c->config.pem_root_certs != NULL) gpr_free(c->config.pem_root_certs);
 }
 
-static int ssl_has_request_metadata(const grpc_credentials *creds) { return 0; }
-
-static int ssl_has_request_metadata_only(const grpc_credentials *creds) {
-  return 0;
-}
-
 static grpc_security_status ssl_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
+    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
     grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
   grpc_ssl_credentials *c = (grpc_ssl_credentials *)creds;
   grpc_security_status status = GRPC_SECURITY_OK;
@@ -278,7 +282,7 @@ static grpc_security_status ssl_create_security_connector(
     }
   }
   status = grpc_ssl_channel_security_connector_create(
-      request_metadata_creds, &c->config, target, overridden_target_name, sc);
+      call_creds, &c->config, target, overridden_target_name, sc);
   if (status != GRPC_SECURITY_OK) {
     return status;
   }
@@ -295,9 +299,8 @@ static grpc_security_status ssl_server_create_security_connector(
   return grpc_ssl_server_security_connector_create(&c->config, sc);
 }
 
-static grpc_credentials_vtable ssl_vtable = {
-    ssl_destruct, ssl_has_request_metadata, ssl_has_request_metadata_only, NULL,
-    ssl_create_security_connector};
+static grpc_channel_credentials_vtable ssl_vtable = {
+    ssl_destruct, ssl_create_security_connector};
 
 static grpc_server_credentials_vtable ssl_server_vtable = {
     ssl_server_destruct, ssl_server_create_security_connector};
@@ -362,7 +365,7 @@ static void ssl_build_server_config(
   }
 }
 
-grpc_credentials *grpc_ssl_credentials_create(
+grpc_channel_credentials *grpc_ssl_credentials_create(
     const char *pem_root_certs, grpc_ssl_pem_key_cert_pair *pem_key_cert_pair,
     void *reserved) {
   grpc_ssl_credentials *c = gpr_malloc(sizeof(grpc_ssl_credentials));
@@ -373,7 +376,7 @@ grpc_credentials *grpc_ssl_credentials_create(
       3, (pem_root_certs, pem_key_cert_pair, reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(grpc_ssl_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_SSL;
+  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
   c->base.vtable = &ssl_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   ssl_build_config(pem_root_certs, pem_key_cert_pair, &c->config);
@@ -393,7 +396,7 @@ grpc_server_credentials *grpc_ssl_server_credentials_create(
           force_client_auth, reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(grpc_ssl_server_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_SSL;
+  c->base.type = GRPC_CHANNEL_CREDENTIALS_TYPE_SSL;
   gpr_ref_init(&c->base.refcount, 1);
   c->base.vtable = &ssl_server_vtable;
   ssl_build_server_config(pem_root_certs, pem_key_cert_pairs,
@@ -415,7 +418,7 @@ static void jwt_reset_cache(grpc_service_account_jwt_access_credentials *c) {
   c->cached.jwt_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
 }
 
-static void jwt_destruct(grpc_credentials *creds) {
+static void jwt_destruct(grpc_call_credentials *creds) {
   grpc_service_account_jwt_access_credentials *c =
       (grpc_service_account_jwt_access_credentials *)creds;
   grpc_auth_json_key_destruct(&c->key);
@@ -423,15 +426,12 @@ static void jwt_destruct(grpc_credentials *creds) {
   gpr_mu_destroy(&c->cache_mu);
 }
 
-static int jwt_has_request_metadata(const grpc_credentials *creds) { return 1; }
-
-static int jwt_has_request_metadata_only(const grpc_credentials *creds) {
-  return 1;
-}
-
-static void jwt_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void jwt_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                     grpc_call_credentials *creds,
+                                     grpc_pollset *pollset,
+                                     const char *service_url,
+                                     grpc_credentials_metadata_cb cb,
+                                     void *user_data) {
   grpc_service_account_jwt_access_credentials *c =
       (grpc_service_account_jwt_access_credentials *)creds;
   gpr_timespec refresh_threshold = gpr_time_from_seconds(
@@ -483,11 +483,10 @@ static void jwt_get_request_metadata(
   }
 }
 
-static grpc_credentials_vtable jwt_vtable = {
-    jwt_destruct, jwt_has_request_metadata, jwt_has_request_metadata_only,
-    jwt_get_request_metadata, NULL};
+static grpc_call_credentials_vtable jwt_vtable = {jwt_destruct,
+                                                  jwt_get_request_metadata};
 
-grpc_credentials *
+grpc_call_credentials *
 grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
     grpc_auth_json_key key, gpr_timespec token_lifetime) {
   grpc_service_account_jwt_access_credentials *c;
@@ -497,7 +496,7 @@ grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
   }
   c = gpr_malloc(sizeof(grpc_service_account_jwt_access_credentials));
   memset(c, 0, sizeof(grpc_service_account_jwt_access_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_JWT;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_JWT;
   gpr_ref_init(&c->base.refcount, 1);
   c->base.vtable = &jwt_vtable;
   c->key = key;
@@ -507,7 +506,7 @@ grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
   return &c->base;
 }
 
-grpc_credentials *grpc_service_account_jwt_access_credentials_create(
+grpc_call_credentials *grpc_service_account_jwt_access_credentials_create(
     const char *json_key, gpr_timespec token_lifetime, void *reserved) {
   GRPC_API_TRACE(
       "grpc_service_account_jwt_access_credentials_create("
@@ -524,7 +523,7 @@ grpc_credentials *grpc_service_account_jwt_access_credentials_create(
 
 /* -- Oauth2TokenFetcher credentials -- */
 
-static void oauth2_token_fetcher_destruct(grpc_credentials *creds) {
+static void oauth2_token_fetcher_destruct(grpc_call_credentials *creds) {
   grpc_oauth2_token_fetcher_credentials *c =
       (grpc_oauth2_token_fetcher_credentials *)creds;
   grpc_credentials_md_store_unref(c->access_token_md);
@@ -532,16 +531,6 @@ static void oauth2_token_fetcher_destruct(grpc_credentials *creds) {
   grpc_httpcli_context_destroy(&c->httpcli_context);
 }
 
-static int oauth2_token_fetcher_has_request_metadata(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
-static int oauth2_token_fetcher_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
 grpc_credentials_status
 grpc_oauth2_token_fetcher_credentials_parse_server_response(
     const grpc_httpcli_response *response, grpc_credentials_md_store **token_md,
@@ -659,8 +648,9 @@ static void on_oauth2_token_fetcher_http_response(
 }
 
 static void oauth2_token_fetcher_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+    grpc_exec_ctx *exec_ctx, grpc_call_credentials *creds,
+    grpc_pollset *pollset, const char *service_url,
+    grpc_credentials_metadata_cb cb, void *user_data) {
   grpc_oauth2_token_fetcher_credentials *c =
       (grpc_oauth2_token_fetcher_credentials *)creds;
   gpr_timespec refresh_threshold = gpr_time_from_seconds(
@@ -693,7 +683,7 @@ static void oauth2_token_fetcher_get_request_metadata(
 static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
                                       grpc_fetch_oauth2_func fetch_func) {
   memset(c, 0, sizeof(grpc_oauth2_token_fetcher_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
   gpr_ref_init(&c->base.refcount, 1);
   gpr_mu_init(&c->mu);
   c->token_expiration = gpr_inf_past(GPR_CLOCK_REALTIME);
@@ -703,10 +693,8 @@ static void init_oauth2_token_fetcher(grpc_oauth2_token_fetcher_credentials *c,
 
 /* -- GoogleComputeEngine credentials. -- */
 
-static grpc_credentials_vtable compute_engine_vtable = {
-    oauth2_token_fetcher_destruct, oauth2_token_fetcher_has_request_metadata,
-    oauth2_token_fetcher_has_request_metadata_only,
-    oauth2_token_fetcher_get_request_metadata, NULL};
+static grpc_call_credentials_vtable compute_engine_vtable = {
+    oauth2_token_fetcher_destruct, oauth2_token_fetcher_get_request_metadata};
 
 static void compute_engine_fetch_oauth2(
     grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
@@ -723,7 +711,7 @@ static void compute_engine_fetch_oauth2(
                    response_cb, metadata_req);
 }
 
-grpc_credentials *grpc_google_compute_engine_credentials_create(
+grpc_call_credentials *grpc_google_compute_engine_credentials_create(
     void *reserved) {
   grpc_oauth2_token_fetcher_credentials *c =
       gpr_malloc(sizeof(grpc_oauth2_token_fetcher_credentials));
@@ -737,17 +725,15 @@ grpc_credentials *grpc_google_compute_engine_credentials_create(
 
 /* -- GoogleRefreshToken credentials. -- */
 
-static void refresh_token_destruct(grpc_credentials *creds) {
+static void refresh_token_destruct(grpc_call_credentials *creds) {
   grpc_google_refresh_token_credentials *c =
       (grpc_google_refresh_token_credentials *)creds;
   grpc_auth_refresh_token_destruct(&c->refresh_token);
   oauth2_token_fetcher_destruct(&c->base.base);
 }
 
-static grpc_credentials_vtable refresh_token_vtable = {
-    refresh_token_destruct, oauth2_token_fetcher_has_request_metadata,
-    oauth2_token_fetcher_has_request_metadata_only,
-    oauth2_token_fetcher_get_request_metadata, NULL};
+static grpc_call_credentials_vtable refresh_token_vtable = {
+    refresh_token_destruct, oauth2_token_fetcher_get_request_metadata};
 
 static void refresh_token_fetch_oauth2(
     grpc_exec_ctx *exec_ctx, grpc_credentials_metadata_request *metadata_req,
@@ -773,7 +759,8 @@ static void refresh_token_fetch_oauth2(
   gpr_free(body);
 }
 
-grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
+grpc_call_credentials *
+grpc_refresh_token_credentials_create_from_auth_refresh_token(
     grpc_auth_refresh_token refresh_token) {
   grpc_google_refresh_token_credentials *c;
   if (!grpc_auth_refresh_token_is_valid(&refresh_token)) {
@@ -788,7 +775,7 @@ grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
   return &c->base.base;
 }
 
-grpc_credentials *grpc_google_refresh_token_credentials_create(
+grpc_call_credentials *grpc_google_refresh_token_credentials_create(
     const char *json_refresh_token, void *reserved) {
   GRPC_API_TRACE(
       "grpc_refresh_token_credentials_create(json_refresh_token=%s, "
@@ -801,20 +788,11 @@ grpc_credentials *grpc_google_refresh_token_credentials_create(
 
 /* -- Metadata-only credentials. -- */
 
-static void md_only_test_destruct(grpc_credentials *creds) {
+static void md_only_test_destruct(grpc_call_credentials *creds) {
   grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
   grpc_credentials_md_store_unref(c->md_store);
 }
 
-static int md_only_test_has_request_metadata(const grpc_credentials *creds) {
-  return 1;
-}
-
-static int md_only_test_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
 static void on_simulated_token_fetch_done(void *user_data) {
   grpc_credentials_metadata_request *r =
       (grpc_credentials_metadata_request *)user_data;
@@ -826,9 +804,12 @@ static void on_simulated_token_fetch_done(void *user_data) {
   grpc_exec_ctx_finish(&exec_ctx);
 }
 
-static void md_only_test_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void md_only_test_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                              grpc_call_credentials *creds,
+                                              grpc_pollset *pollset,
+                                              const char *service_url,
+                                              grpc_credentials_metadata_cb cb,
+                                              void *user_data) {
   grpc_md_only_test_credentials *c = (grpc_md_only_test_credentials *)creds;
 
   if (c->is_async) {
@@ -841,18 +822,15 @@ static void md_only_test_get_request_metadata(
   }
 }
 
-static grpc_credentials_vtable md_only_test_vtable = {
-    md_only_test_destruct, md_only_test_has_request_metadata,
-    md_only_test_has_request_metadata_only, md_only_test_get_request_metadata,
-    NULL};
+static grpc_call_credentials_vtable md_only_test_vtable = {
+    md_only_test_destruct, md_only_test_get_request_metadata};
 
-grpc_credentials *grpc_md_only_test_credentials_create(const char *md_key,
-                                                       const char *md_value,
-                                                       int is_async) {
+grpc_call_credentials *grpc_md_only_test_credentials_create(
+    const char *md_key, const char *md_value, int is_async) {
   grpc_md_only_test_credentials *c =
       gpr_malloc(sizeof(grpc_md_only_test_credentials));
   memset(c, 0, sizeof(grpc_md_only_test_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
   c->base.vtable = &md_only_test_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->md_store = grpc_credentials_md_store_create(1);
@@ -863,34 +841,26 @@ grpc_credentials *grpc_md_only_test_credentials_create(const char *md_key,
 
 /* -- Oauth2 Access Token credentials. -- */
 
-static void access_token_destruct(grpc_credentials *creds) {
+static void access_token_destruct(grpc_call_credentials *creds) {
   grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
   grpc_credentials_md_store_unref(c->access_token_md);
 }
 
-static int access_token_has_request_metadata(const grpc_credentials *creds) {
-  return 1;
-}
-
-static int access_token_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 1;
-}
-
-static void access_token_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void access_token_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                              grpc_call_credentials *creds,
+                                              grpc_pollset *pollset,
+                                              const char *service_url,
+                                              grpc_credentials_metadata_cb cb,
+                                              void *user_data) {
   grpc_access_token_credentials *c = (grpc_access_token_credentials *)creds;
   cb(exec_ctx, user_data, c->access_token_md->entries, 1, GRPC_CREDENTIALS_OK);
 }
 
-static grpc_credentials_vtable access_token_vtable = {
-    access_token_destruct, access_token_has_request_metadata,
-    access_token_has_request_metadata_only, access_token_get_request_metadata,
-    NULL};
+static grpc_call_credentials_vtable access_token_vtable = {
+    access_token_destruct, access_token_get_request_metadata};
 
-grpc_credentials *grpc_access_token_credentials_create(const char *access_token,
-                                                       void *reserved) {
+grpc_call_credentials *grpc_access_token_credentials_create(
+    const char *access_token, void *reserved) {
   grpc_access_token_credentials *c =
       gpr_malloc(sizeof(grpc_access_token_credentials));
   char *token_md_value;
@@ -900,7 +870,7 @@ grpc_credentials *grpc_access_token_credentials_create(const char *access_token,
       2, (access_token, reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(grpc_access_token_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_OAUTH2;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_OAUTH2;
   c->base.vtable = &access_token_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->access_token_md = grpc_credentials_md_store_create(1);
@@ -913,31 +883,11 @@ grpc_credentials *grpc_access_token_credentials_create(const char *access_token,
 
 /* -- Fake transport security credentials. -- */
 
-static void fake_transport_security_credentials_destruct(
-    grpc_credentials *creds) {
-  /* Nothing to do here. */
-}
-
-static void fake_transport_security_server_credentials_destruct(
-    grpc_server_credentials *creds) {
-  /* Nothing to do here. */
-}
-
-static int fake_transport_security_has_request_metadata(
-    const grpc_credentials *creds) {
-  return 0;
-}
-
-static int fake_transport_security_has_request_metadata_only(
-    const grpc_credentials *creds) {
-  return 0;
-}
-
 static grpc_security_status fake_transport_security_create_security_connector(
-    grpc_credentials *c, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
+    grpc_channel_credentials *c, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
     grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
-  *sc = grpc_fake_channel_security_connector_create(request_metadata_creds, 1);
+  *sc = grpc_fake_channel_security_connector_create(call_creds, 1);
   return GRPC_SECURITY_OK;
 }
 
@@ -948,21 +898,19 @@ fake_transport_security_server_create_security_connector(
   return GRPC_SECURITY_OK;
 }
 
-static grpc_credentials_vtable fake_transport_security_credentials_vtable = {
-    fake_transport_security_credentials_destruct,
-    fake_transport_security_has_request_metadata,
-    fake_transport_security_has_request_metadata_only, NULL,
-    fake_transport_security_create_security_connector};
+static grpc_channel_credentials_vtable
+    fake_transport_security_credentials_vtable = {
+        NULL, fake_transport_security_create_security_connector};
 
 static grpc_server_credentials_vtable
     fake_transport_security_server_credentials_vtable = {
-        fake_transport_security_server_credentials_destruct,
-        fake_transport_security_server_create_security_connector};
+        NULL, fake_transport_security_server_create_security_connector};
 
-grpc_credentials *grpc_fake_transport_security_credentials_create(void) {
-  grpc_credentials *c = gpr_malloc(sizeof(grpc_credentials));
-  memset(c, 0, sizeof(grpc_credentials));
-  c->type = GRPC_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
+grpc_channel_credentials *grpc_fake_transport_security_credentials_create(
+    void) {
+  grpc_channel_credentials *c = gpr_malloc(sizeof(grpc_channel_credentials));
+  memset(c, 0, sizeof(grpc_channel_credentials));
+  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
   c->vtable = &fake_transport_security_credentials_vtable;
   gpr_ref_init(&c->refcount, 1);
   return c;
@@ -972,69 +920,46 @@ grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
     void) {
   grpc_server_credentials *c = gpr_malloc(sizeof(grpc_server_credentials));
   memset(c, 0, sizeof(grpc_server_credentials));
-  c->type = GRPC_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
+  c->type = GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY;
   gpr_ref_init(&c->refcount, 1);
   c->vtable = &fake_transport_security_server_credentials_vtable;
   return c;
 }
 
-/* -- Composite credentials. -- */
+/* -- Composite call credentials. -- */
 
 typedef struct {
-  grpc_composite_credentials *composite_creds;
+  grpc_composite_call_credentials *composite_creds;
   size_t creds_index;
   grpc_credentials_md_store *md_elems;
   char *service_url;
   void *user_data;
   grpc_pollset *pollset;
   grpc_credentials_metadata_cb cb;
-} grpc_composite_credentials_metadata_context;
+} grpc_composite_call_credentials_metadata_context;
 
-static void composite_destruct(grpc_credentials *creds) {
-  grpc_composite_credentials *c = (grpc_composite_credentials *)creds;
+static void composite_call_destruct(grpc_call_credentials *creds) {
+  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
   size_t i;
   for (i = 0; i < c->inner.num_creds; i++) {
-    grpc_credentials_unref(c->inner.creds_array[i]);
+    grpc_call_credentials_unref(c->inner.creds_array[i]);
   }
   gpr_free(c->inner.creds_array);
 }
 
-static int composite_has_request_metadata(const grpc_credentials *creds) {
-  const grpc_composite_credentials *c =
-      (const grpc_composite_credentials *)creds;
-  size_t i;
-  for (i = 0; i < c->inner.num_creds; i++) {
-    if (grpc_credentials_has_request_metadata(c->inner.creds_array[i])) {
-      return 1;
-    }
-  }
-  return 0;
-}
-
-static int composite_has_request_metadata_only(const grpc_credentials *creds) {
-  const grpc_composite_credentials *c =
-      (const grpc_composite_credentials *)creds;
-  size_t i;
-  for (i = 0; i < c->inner.num_creds; i++) {
-    if (!grpc_credentials_has_request_metadata_only(c->inner.creds_array[i])) {
-      return 0;
-    }
-  }
-  return 1;
-}
-
-static void composite_md_context_destroy(
-    grpc_composite_credentials_metadata_context *ctx) {
+static void composite_call_md_context_destroy(
+    grpc_composite_call_credentials_metadata_context *ctx) {
   grpc_credentials_md_store_unref(ctx->md_elems);
   if (ctx->service_url != NULL) gpr_free(ctx->service_url);
   gpr_free(ctx);
 }
 
-static void composite_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
-                                  grpc_credentials_md *md_elems, size_t num_md,
-                                  grpc_credentials_status status) {
-  grpc_composite_credentials_metadata_context *ctx =
-      (grpc_composite_credentials_metadata_context *)user_data;
+static void composite_call_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
+                                       grpc_credentials_md *md_elems,
+                                       size_t num_md,
+                                       grpc_credentials_status status) {
+  grpc_composite_call_credentials_metadata_context *ctx =
+      (grpc_composite_call_credentials_metadata_context *)user_data;
   if (status != GRPC_CREDENTIALS_OK) {
     ctx->cb(exec_ctx, ctx->user_data, NULL, 0, status);
     return;
@@ -1050,158 +975,114 @@ static void composite_metadata_cb(grpc_exec_ctx *exec_ctx, void *user_data,
   }
 
   /* See if we need to get some more metadata. */
-  while (ctx->creds_index < ctx->composite_creds->inner.num_creds) {
-    grpc_credentials *inner_creds =
+  if (ctx->creds_index < ctx->composite_creds->inner.num_creds) {
+    grpc_call_credentials *inner_creds =
         ctx->composite_creds->inner.creds_array[ctx->creds_index++];
-    if (grpc_credentials_has_request_metadata(inner_creds)) {
-      grpc_credentials_get_request_metadata(exec_ctx, inner_creds, ctx->pollset,
-                                            ctx->service_url,
-                                            composite_metadata_cb, ctx);
-      return;
-    }
+    grpc_call_credentials_get_request_metadata(exec_ctx, inner_creds,
+                                               ctx->pollset, ctx->service_url,
+                                               composite_call_metadata_cb, ctx);
+    return;
   }
 
   /* We're done!. */
   ctx->cb(exec_ctx, ctx->user_data, ctx->md_elems->entries,
           ctx->md_elems->num_entries, GRPC_CREDENTIALS_OK);
-  composite_md_context_destroy(ctx);
+  composite_call_md_context_destroy(ctx);
 }
 
-static void composite_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
-  grpc_composite_credentials *c = (grpc_composite_credentials *)creds;
-  grpc_composite_credentials_metadata_context *ctx;
-  if (!grpc_credentials_has_request_metadata(creds)) {
-    cb(exec_ctx, user_data, NULL, 0, GRPC_CREDENTIALS_OK);
-    return;
-  }
-  ctx = gpr_malloc(sizeof(grpc_composite_credentials_metadata_context));
-  memset(ctx, 0, sizeof(grpc_composite_credentials_metadata_context));
+static void composite_call_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                                grpc_call_credentials *creds,
+                                                grpc_pollset *pollset,
+                                                const char *service_url,
+                                                grpc_credentials_metadata_cb cb,
+                                                void *user_data) {
+  grpc_composite_call_credentials *c = (grpc_composite_call_credentials *)creds;
+  grpc_composite_call_credentials_metadata_context *ctx;
+
+  ctx = gpr_malloc(sizeof(grpc_composite_call_credentials_metadata_context));
+  memset(ctx, 0, sizeof(grpc_composite_call_credentials_metadata_context));
   ctx->service_url = gpr_strdup(service_url);
   ctx->user_data = user_data;
   ctx->cb = cb;
   ctx->composite_creds = c;
   ctx->pollset = pollset;
   ctx->md_elems = grpc_credentials_md_store_create(c->inner.num_creds);
-  while (ctx->creds_index < c->inner.num_creds) {
-    grpc_credentials *inner_creds = c->inner.creds_array[ctx->creds_index++];
-    if (grpc_credentials_has_request_metadata(inner_creds)) {
-      grpc_credentials_get_request_metadata(exec_ctx, inner_creds, pollset,
-                                            service_url, composite_metadata_cb,
-                                            ctx);
-      return;
-    }
-  }
-  GPR_ASSERT(0); /* Should have exited before. */
-}
-
-static grpc_security_status composite_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
-  grpc_composite_credentials *c = (grpc_composite_credentials *)creds;
-  if (c->connector_creds == NULL) {
-    gpr_log(GPR_ERROR,
-            "Cannot create security connector, missing connector credentials.");
-    return GRPC_SECURITY_ERROR;
-  }
-  return grpc_credentials_create_security_connector(c->connector_creds, target,
-                                                    args, creds, sc, new_args);
+  grpc_call_credentials_get_request_metadata(
+      exec_ctx, c->inner.creds_array[ctx->creds_index++], pollset, service_url,
+      composite_call_metadata_cb, ctx);
 }
 
-static grpc_credentials_vtable composite_credentials_vtable = {
-    composite_destruct, composite_has_request_metadata,
-    composite_has_request_metadata_only, composite_get_request_metadata,
-    composite_create_security_connector};
+static grpc_call_credentials_vtable composite_call_credentials_vtable = {
+    composite_call_destruct, composite_call_get_request_metadata};
 
-static grpc_credentials_array get_creds_array(grpc_credentials **creds_addr) {
-  grpc_credentials_array result;
-  grpc_credentials *creds = *creds_addr;
+static grpc_call_credentials_array get_creds_array(
+    grpc_call_credentials **creds_addr) {
+  grpc_call_credentials_array result;
+  grpc_call_credentials *creds = *creds_addr;
   result.creds_array = creds_addr;
   result.num_creds = 1;
-  if (strcmp(creds->type, GRPC_CREDENTIALS_TYPE_COMPOSITE) == 0) {
-    result = *grpc_composite_credentials_get_credentials(creds);
+  if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
+    result = *grpc_composite_call_credentials_get_credentials(creds);
   }
   return result;
 }
 
-grpc_credentials *grpc_composite_credentials_create(grpc_credentials *creds1,
-                                                    grpc_credentials *creds2,
-                                                    void *reserved) {
+grpc_call_credentials *grpc_composite_call_credentials_create(
+    grpc_call_credentials *creds1, grpc_call_credentials *creds2,
+    void *reserved) {
   size_t i;
   size_t creds_array_byte_size;
-  grpc_credentials_array creds1_array;
-  grpc_credentials_array creds2_array;
-  grpc_composite_credentials *c;
+  grpc_call_credentials_array creds1_array;
+  grpc_call_credentials_array creds2_array;
+  grpc_composite_call_credentials *c;
   GRPC_API_TRACE(
-      "grpc_composite_credentials_create(creds1=%p, creds2=%p, "
+      "grpc_composite_call_credentials_create(creds1=%p, creds2=%p, "
       "reserved=%p)",
       3, (creds1, creds2, reserved));
   GPR_ASSERT(reserved == NULL);
   GPR_ASSERT(creds1 != NULL);
   GPR_ASSERT(creds2 != NULL);
-  c = gpr_malloc(sizeof(grpc_composite_credentials));
-  memset(c, 0, sizeof(grpc_composite_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_COMPOSITE;
-  c->base.vtable = &composite_credentials_vtable;
+  c = gpr_malloc(sizeof(grpc_composite_call_credentials));
+  memset(c, 0, sizeof(grpc_composite_call_credentials));
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE;
+  c->base.vtable = &composite_call_credentials_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   creds1_array = get_creds_array(&creds1);
   creds2_array = get_creds_array(&creds2);
   c->inner.num_creds = creds1_array.num_creds + creds2_array.num_creds;
-  creds_array_byte_size = c->inner.num_creds * sizeof(grpc_credentials *);
+  creds_array_byte_size = c->inner.num_creds * sizeof(grpc_call_credentials *);
   c->inner.creds_array = gpr_malloc(creds_array_byte_size);
   memset(c->inner.creds_array, 0, creds_array_byte_size);
   for (i = 0; i < creds1_array.num_creds; i++) {
-    grpc_credentials *cur_creds = creds1_array.creds_array[i];
-    if (!grpc_credentials_has_request_metadata_only(cur_creds)) {
-      if (c->connector_creds == NULL) {
-        c->connector_creds = cur_creds;
-      } else {
-        gpr_log(GPR_ERROR, "Cannot compose multiple connector credentials.");
-        goto fail;
-      }
-    }
-    c->inner.creds_array[i] = grpc_credentials_ref(cur_creds);
+    grpc_call_credentials *cur_creds = creds1_array.creds_array[i];
+    c->inner.creds_array[i] = grpc_call_credentials_ref(cur_creds);
   }
   for (i = 0; i < creds2_array.num_creds; i++) {
-    grpc_credentials *cur_creds = creds2_array.creds_array[i];
-    if (!grpc_credentials_has_request_metadata_only(cur_creds)) {
-      if (c->connector_creds == NULL) {
-        c->connector_creds = cur_creds;
-      } else {
-        gpr_log(GPR_ERROR, "Cannot compose multiple connector credentials.");
-        goto fail;
-      }
-    }
+    grpc_call_credentials *cur_creds = creds2_array.creds_array[i];
     c->inner.creds_array[i + creds1_array.num_creds] =
-        grpc_credentials_ref(cur_creds);
+        grpc_call_credentials_ref(cur_creds);
   }
   return &c->base;
-
-fail:
-  grpc_credentials_unref(&c->base);
-  return NULL;
 }
 
-const grpc_credentials_array *grpc_composite_credentials_get_credentials(
-    grpc_credentials *creds) {
-  const grpc_composite_credentials *c =
-      (const grpc_composite_credentials *)creds;
-  GPR_ASSERT(strcmp(creds->type, GRPC_CREDENTIALS_TYPE_COMPOSITE) == 0);
+const grpc_call_credentials_array *
+grpc_composite_call_credentials_get_credentials(grpc_call_credentials *creds) {
+  const grpc_composite_call_credentials *c =
+      (const grpc_composite_call_credentials *)creds;
+  GPR_ASSERT(strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0);
   return &c->inner;
 }
 
-grpc_credentials *grpc_credentials_contains_type(
-    grpc_credentials *creds, const char *type,
-    grpc_credentials **composite_creds) {
+grpc_call_credentials *grpc_credentials_contains_type(
+    grpc_call_credentials *creds, const char *type,
+    grpc_call_credentials **composite_creds) {
   size_t i;
   if (strcmp(creds->type, type) == 0) {
     if (composite_creds != NULL) *composite_creds = NULL;
     return creds;
-  } else if (strcmp(creds->type, GRPC_CREDENTIALS_TYPE_COMPOSITE) == 0) {
-    const grpc_credentials_array *inner_creds_array =
-        grpc_composite_credentials_get_credentials(creds);
+  } else if (strcmp(creds->type, GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE) == 0) {
+    const grpc_call_credentials_array *inner_creds_array =
+        grpc_composite_call_credentials_get_credentials(creds);
     for (i = 0; i < inner_creds_array->num_creds; i++) {
       if (strcmp(type, inner_creds_array->creds_array[i]->type) == 0) {
         if (composite_creds != NULL) *composite_creds = creds;
@@ -1214,30 +1095,26 @@ grpc_credentials *grpc_credentials_contains_type(
 
 /* -- IAM credentials. -- */
 
-static void iam_destruct(grpc_credentials *creds) {
+static void iam_destruct(grpc_call_credentials *creds) {
   grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
   grpc_credentials_md_store_unref(c->iam_md);
 }
 
-static int iam_has_request_metadata(const grpc_credentials *creds) { return 1; }
-
-static int iam_has_request_metadata_only(const grpc_credentials *creds) {
-  return 1;
-}
-
-static void iam_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void iam_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                     grpc_call_credentials *creds,
+                                     grpc_pollset *pollset,
+                                     const char *service_url,
+                                     grpc_credentials_metadata_cb cb,
+                                     void *user_data) {
   grpc_google_iam_credentials *c = (grpc_google_iam_credentials *)creds;
   cb(exec_ctx, user_data, c->iam_md->entries, c->iam_md->num_entries,
      GRPC_CREDENTIALS_OK);
 }
 
-static grpc_credentials_vtable iam_vtable = {
-    iam_destruct, iam_has_request_metadata, iam_has_request_metadata_only,
-    iam_get_request_metadata, NULL};
+static grpc_call_credentials_vtable iam_vtable = {iam_destruct,
+                                                  iam_get_request_metadata};
 
-grpc_credentials *grpc_google_iam_credentials_create(
+grpc_call_credentials *grpc_google_iam_credentials_create(
     const char *token, const char *authority_selector, void *reserved) {
   grpc_google_iam_credentials *c;
   GRPC_API_TRACE(
@@ -1249,7 +1126,7 @@ grpc_credentials *grpc_google_iam_credentials_create(
   GPR_ASSERT(authority_selector != NULL);
   c = gpr_malloc(sizeof(grpc_google_iam_credentials));
   memset(c, 0, sizeof(grpc_google_iam_credentials));
-  c->base.type = GRPC_CREDENTIALS_TYPE_IAM;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_IAM;
   c->base.vtable = &iam_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->iam_md = grpc_credentials_md_store_create(2);
@@ -1267,21 +1144,13 @@ typedef struct {
   grpc_credentials_metadata_cb cb;
 } grpc_metadata_plugin_request;
 
-static void plugin_destruct(grpc_credentials *creds) {
+static void plugin_destruct(grpc_call_credentials *creds) {
   grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
   if (c->plugin.state != NULL && c->plugin.destroy != NULL) {
     c->plugin.destroy(c->plugin.state);
   }
 }
 
-static int plugin_has_request_metadata(const grpc_credentials *creds) {
-  return 1;
-}
-
-static int plugin_has_request_metadata_only(const grpc_credentials *creds) {
-  return 1;
-}
-
 static void plugin_md_request_metadata_ready(void *request,
                                              const grpc_metadata *md,
                                              size_t num_md,
@@ -1320,9 +1189,12 @@ static void plugin_md_request_metadata_ready(void *request,
   grpc_exec_ctx_finish(&exec_ctx);
 }
 
-static void plugin_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data) {
+static void plugin_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                        grpc_call_credentials *creds,
+                                        grpc_pollset *pollset,
+                                        const char *service_url,
+                                        grpc_credentials_metadata_cb cb,
+                                        void *user_data) {
   grpc_plugin_credentials *c = (grpc_plugin_credentials *)creds;
   if (c->plugin.get_metadata != NULL) {
     grpc_metadata_plugin_request *request = gpr_malloc(sizeof(*request));
@@ -1336,18 +1208,75 @@ static void plugin_get_request_metadata(
   }
 }
 
-static grpc_credentials_vtable plugin_vtable = {
-    plugin_destruct, plugin_has_request_metadata,
-    plugin_has_request_metadata_only, plugin_get_request_metadata, NULL};
+static grpc_call_credentials_vtable plugin_vtable = {
+    plugin_destruct, plugin_get_request_metadata};
 
-grpc_credentials *grpc_metadata_credentials_create_from_plugin(
+grpc_call_credentials *grpc_metadata_credentials_create_from_plugin(
     grpc_metadata_credentials_plugin plugin, void *reserved) {
   grpc_plugin_credentials *c = gpr_malloc(sizeof(*c));
+  GRPC_API_TRACE("grpc_metadata_credentials_create_from_plugin(reserved=%p)", 1,
+                 (reserved));
   GPR_ASSERT(reserved == NULL);
   memset(c, 0, sizeof(*c));
-  c->base.type = GRPC_CREDENTIALS_TYPE_METADATA_PLUGIN;
+  c->base.type = GRPC_CALL_CREDENTIALS_TYPE_METADATA_PLUGIN;
   c->base.vtable = &plugin_vtable;
   gpr_ref_init(&c->base.refcount, 1);
   c->plugin = plugin;
   return &c->base;
 }
+
+/* -- Composite channel credentials. -- */
+
+static void composite_channel_destruct(grpc_channel_credentials *creds) {
+  grpc_composite_channel_credentials *c =
+      (grpc_composite_channel_credentials *)creds;
+  grpc_channel_credentials_unref(c->inner_creds);
+  grpc_call_credentials_unref(c->call_creds);
+}
+
+static grpc_security_status composite_channel_create_security_connector(
+    grpc_channel_credentials *creds, grpc_call_credentials *call_creds,
+    const char *target, const grpc_channel_args *args,
+    grpc_channel_security_connector **sc, grpc_channel_args **new_args) {
+  grpc_composite_channel_credentials *c =
+      (grpc_composite_channel_credentials *)creds;
+  grpc_security_status status = GRPC_SECURITY_ERROR;
+
+  GPR_ASSERT(c->inner_creds != NULL && c->call_creds != NULL &&
+             c->inner_creds->vtable != NULL &&
+             c->inner_creds->vtable->create_security_connector != NULL);
+  /* If we are passed a call_creds, create a call composite to pass it
+     downstream. */
+  if (call_creds != NULL) {
+    grpc_call_credentials *composite_call_creds =
+        grpc_composite_call_credentials_create(c->call_creds, call_creds, NULL);
+    status = c->inner_creds->vtable->create_security_connector(
+        c->inner_creds, composite_call_creds, target, args, sc, new_args);
+    grpc_call_credentials_unref(composite_call_creds);
+  } else {
+    status = c->inner_creds->vtable->create_security_connector(
+        c->inner_creds, c->call_creds, target, args, sc, new_args);
+  }
+  return status;
+}
+
+static grpc_channel_credentials_vtable composite_channel_credentials_vtable = {
+    composite_channel_destruct, composite_channel_create_security_connector};
+
+grpc_channel_credentials *grpc_composite_channel_credentials_create(
+    grpc_channel_credentials *channel_creds, grpc_call_credentials *call_creds,
+    void *reserved) {
+  grpc_composite_channel_credentials *c = gpr_malloc(sizeof(*c));
+  memset(c, 0, sizeof(*c));
+  GPR_ASSERT(channel_creds != NULL && call_creds != NULL && reserved == NULL);
+  GRPC_API_TRACE(
+      "grpc_composite_channel_credentials_create(channel_creds=%p, "
+      "call_creds=%p, reserved=%p)",
+      3, (channel_creds, call_creds, reserved));
+  c->base.type = channel_creds->type;
+  c->base.vtable = &composite_channel_credentials_vtable;
+  gpr_ref_init(&c->base.refcount, 1);
+  c->inner_creds = grpc_channel_credentials_ref(channel_creds);
+  c->call_creds = grpc_call_credentials_ref(call_creds);
+  return &c->base;
+}
diff --git a/src/core/security/credentials.h b/src/core/security/credentials.h
index c74beef0e4..132060910e 100644
--- a/src/core/security/credentials.h
+++ b/src/core/security/credentials.h
@@ -54,15 +54,17 @@ typedef enum {
 
 #define GRPC_FAKE_TRANSPORT_SECURITY_TYPE "fake"
 
-#define GRPC_CREDENTIALS_TYPE_SSL "Ssl"
-#define GRPC_CREDENTIALS_TYPE_OAUTH2 "Oauth2"
-#define GRPC_CREDENTIALS_TYPE_METADATA_PLUGIN "Plugin"
-#define GRPC_CREDENTIALS_TYPE_JWT "Jwt"
-#define GRPC_CREDENTIALS_TYPE_IAM "Iam"
-#define GRPC_CREDENTIALS_TYPE_COMPOSITE "Composite"
-#define GRPC_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY "FakeTransportSecurity"
-
-#define GRPC_AUTHORIZATION_METADATA_KEY "Authorization"
+#define GRPC_CHANNEL_CREDENTIALS_TYPE_SSL "Ssl"
+#define GRPC_CHANNEL_CREDENTIALS_TYPE_FAKE_TRANSPORT_SECURITY \
+  "FakeTransportSecurity"
+
+#define GRPC_CALL_CREDENTIALS_TYPE_OAUTH2 "Oauth2"
+#define GRPC_CALL_CREDENTIALS_TYPE_METADATA_PLUGIN "Plugin"
+#define GRPC_CALL_CREDENTIALS_TYPE_JWT "Jwt"
+#define GRPC_CALL_CREDENTIALS_TYPE_IAM "Iam"
+#define GRPC_CALL_CREDENTIALS_TYPE_COMPOSITE "Composite"
+
+#define GRPC_AUTHORIZATION_METADATA_KEY "authorization"
 #define GRPC_IAM_AUTHORIZATION_TOKEN_METADATA_KEY \
   "x-goog-iam-authorization-token"
 #define GRPC_IAM_AUTHORITY_SELECTOR_METADATA_KEY "x-goog-iam-authority-selector"
@@ -87,6 +89,41 @@ typedef enum {
 #define GRPC_REFRESH_TOKEN_POST_BODY_FORMAT_STRING \
   "client_id=%s&client_secret=%s&refresh_token=%s&grant_type=refresh_token"
 
+/* --- Google utils --- */
+
+/* It is the caller's responsibility to gpr_free the result if not NULL. */
+char *grpc_get_well_known_google_credentials_file_path(void);
+
+/* --- grpc_channel_credentials. --- */
+
+typedef struct {
+  void (*destruct)(grpc_channel_credentials *c);
+
+  grpc_security_status (*create_security_connector)(
+      grpc_channel_credentials *c, grpc_call_credentials *call_creds,
+      const char *target, const grpc_channel_args *args,
+      grpc_channel_security_connector **sc, grpc_channel_args **new_args);
+} grpc_channel_credentials_vtable;
+
+struct grpc_channel_credentials {
+  const grpc_channel_credentials_vtable *vtable;
+  const char *type;
+  gpr_refcount refcount;
+};
+
+grpc_channel_credentials *grpc_channel_credentials_ref(
+    grpc_channel_credentials *creds);
+void grpc_channel_credentials_unref(grpc_channel_credentials *creds);
+
+/* Creates a security connector for the channel. May also create new channel
+   args for the channel to be used in place of the passed in const args if
+   returned non NULL. In that case the caller is responsible for destroying
+   new_args after channel creation. */
+grpc_security_status grpc_channel_credentials_create_security_connector(
+    grpc_channel_credentials *creds, const char *target,
+    const grpc_channel_args *args, grpc_channel_security_connector **sc,
+    grpc_channel_args **new_args);
+
 /* --- grpc_credentials_md. --- */
 
 typedef struct {
@@ -113,16 +150,7 @@ grpc_credentials_md_store *grpc_credentials_md_store_ref(
     grpc_credentials_md_store *store);
 void grpc_credentials_md_store_unref(grpc_credentials_md_store *store);
 
-/* --- grpc_credentials. --- */
-
-/* Creates a fake transport security credentials object for testing. */
-grpc_credentials *grpc_fake_transport_security_credentials_create(void);
-/* Creates a fake server transport security credentials object for testing. */
-grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
-    void);
-
-/* It is the caller's responsibility to gpr_free the result if not NULL. */
-char *grpc_get_well_known_google_credentials_file_path(void);
+/* --- grpc_call_credentials. --- */
 
 typedef void (*grpc_credentials_metadata_cb)(grpc_exec_ctx *exec_ctx,
                                              void *user_data,
@@ -131,57 +159,45 @@ typedef void (*grpc_credentials_metadata_cb)(grpc_exec_ctx *exec_ctx,
                                              grpc_credentials_status status);
 
 typedef struct {
-  void (*destruct)(grpc_credentials *c);
-  int (*has_request_metadata)(const grpc_credentials *c);
-  int (*has_request_metadata_only)(const grpc_credentials *c);
-  void (*get_request_metadata)(grpc_exec_ctx *exec_ctx, grpc_credentials *c,
-                               grpc_pollset *pollset, const char *service_url,
+  void (*destruct)(grpc_call_credentials *c);
+  void (*get_request_metadata)(grpc_exec_ctx *exec_ctx,
+                               grpc_call_credentials *c, grpc_pollset *pollset,
+                               const char *service_url,
                                grpc_credentials_metadata_cb cb,
                                void *user_data);
-  grpc_security_status (*create_security_connector)(
-      grpc_credentials *c, const char *target, const grpc_channel_args *args,
-      grpc_credentials *request_metadata_creds,
-      grpc_channel_security_connector **sc, grpc_channel_args **new_args);
-} grpc_credentials_vtable;
+} grpc_call_credentials_vtable;
 
-struct grpc_credentials {
-  const grpc_credentials_vtable *vtable;
+struct grpc_call_credentials {
+  const grpc_call_credentials_vtable *vtable;
   const char *type;
   gpr_refcount refcount;
 };
 
-grpc_credentials *grpc_credentials_ref(grpc_credentials *creds);
-void grpc_credentials_unref(grpc_credentials *creds);
-int grpc_credentials_has_request_metadata(grpc_credentials *creds);
-int grpc_credentials_has_request_metadata_only(grpc_credentials *creds);
-void grpc_credentials_get_request_metadata(
-    grpc_exec_ctx *exec_ctx, grpc_credentials *creds, grpc_pollset *pollset,
-    const char *service_url, grpc_credentials_metadata_cb cb, void *user_data);
-
-/* Creates a security connector for the channel. May also create new channel
-   args for the channel to be used in place of the passed in const args if
-   returned non NULL. In that case the caller is responsible for destroying
-   new_args after channel creation. */
-grpc_security_status grpc_credentials_create_security_connector(
-    grpc_credentials *creds, const char *target, const grpc_channel_args *args,
-    grpc_credentials *request_metadata_creds,
-    grpc_channel_security_connector **sc, grpc_channel_args **new_args);
+grpc_call_credentials *grpc_call_credentials_ref(grpc_call_credentials *creds);
+void grpc_call_credentials_unref(grpc_call_credentials *creds);
+void grpc_call_credentials_get_request_metadata(grpc_exec_ctx *exec_ctx,
+                                                grpc_call_credentials *creds,
+                                                grpc_pollset *pollset,
+                                                const char *service_url,
+                                                grpc_credentials_metadata_cb cb,
+                                                void *user_data);
 
 typedef struct {
-  grpc_credentials **creds_array;
+  grpc_call_credentials **creds_array;
   size_t num_creds;
-} grpc_credentials_array;
+} grpc_call_credentials_array;
 
-const grpc_credentials_array *grpc_composite_credentials_get_credentials(
-    grpc_credentials *composite_creds);
+const grpc_call_credentials_array *
+grpc_composite_call_credentials_get_credentials(
+    grpc_call_credentials *composite_creds);
 
 /* Returns creds if creds is of the specified type or the inner creds of the
    specified type (if found), if the creds is of type COMPOSITE.
    If composite_creds is not NULL, *composite_creds will point to creds if of
    type COMPOSITE in case of success. */
-grpc_credentials *grpc_credentials_contains_type(
-    grpc_credentials *creds, const char *type,
-    grpc_credentials **composite_creds);
+grpc_call_credentials *grpc_credentials_contains_type(
+    grpc_call_credentials *creds, const char *type,
+    grpc_call_credentials **composite_creds);
 
 /* Exposed for testing only. */
 grpc_credentials_status
@@ -192,19 +208,19 @@ void grpc_flush_cached_google_default_credentials(void);
 
 /* Metadata-only credentials with the specified key and value where
    asynchronicity can be simulated for testing. */
-grpc_credentials *grpc_md_only_test_credentials_create(const char *md_key,
-                                                       const char *md_value,
-                                                       int is_async);
+grpc_call_credentials *grpc_md_only_test_credentials_create(
+    const char *md_key, const char *md_value, int is_async);
 
 /* Private constructor for jwt credentials from an already parsed json key.
    Takes ownership of the key. */
-grpc_credentials *
+grpc_call_credentials *
 grpc_service_account_jwt_access_credentials_create_from_auth_json_key(
     grpc_auth_json_key key, gpr_timespec token_lifetime);
 
 /* Private constructor for refresh token credentials from an already parsed
    refresh token. Takes ownership of the refresh token. */
-grpc_credentials *grpc_refresh_token_credentials_create_from_auth_refresh_token(
+grpc_call_credentials *
+grpc_refresh_token_credentials_create_from_auth_refresh_token(
     grpc_auth_refresh_token token);
 
 /* --- grpc_server_credentials. --- */
@@ -237,10 +253,18 @@ grpc_server_credentials *grpc_server_credentials_from_arg(const grpc_arg *arg);
 grpc_server_credentials *grpc_find_server_credentials_in_args(
     const grpc_channel_args *args);
 
+/* -- Fake transport security credentials. -- */
+
+/* Creates a fake transport security credentials object for testing. */
+grpc_channel_credentials *grpc_fake_transport_security_credentials_create(void);
+/* Creates a fake server transport security credentials object for testing. */
+grpc_server_credentials *grpc_fake_transport_security_server_credentials_create(
+    void);
+
 /* -- Ssl credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_channel_credentials base;
   grpc_ssl_config config;
 } grpc_ssl_credentials;
 
@@ -249,10 +273,18 @@ typedef struct {
   grpc_ssl_server_config config;
 } grpc_ssl_server_credentials;
 
+/* -- Channel composite credentials. -- */
+
+typedef struct {
+  grpc_channel_credentials base;
+  grpc_channel_credentials *inner_creds;
+  grpc_call_credentials *call_creds;
+} grpc_composite_channel_credentials;
+
 /* -- Jwt credentials -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
 
   /* Have a simple cache for now with just 1 entry. We could have a map based on
      the service_url for a more sophisticated one. */
@@ -283,7 +315,7 @@ typedef void (*grpc_fetch_oauth2_func)(grpc_exec_ctx *exec_ctx,
                                        gpr_timespec deadline);
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   gpr_mu mu;
   grpc_credentials_md_store *access_token_md;
   gpr_timespec token_expiration;
@@ -301,14 +333,14 @@ typedef struct {
 /* -- Oauth2 Access Token credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_credentials_md_store *access_token_md;
 } grpc_access_token_credentials;
 
 /* --  Metadata-only Test credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_credentials_md_store *md_store;
   int is_async;
 } grpc_md_only_test_credentials;
@@ -316,22 +348,21 @@ typedef struct {
 /* -- GoogleIAM credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_credentials_md_store *iam_md;
 } grpc_google_iam_credentials;
 
 /* -- Composite credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
-  grpc_credentials_array inner;
-  grpc_credentials *connector_creds;
-} grpc_composite_credentials;
+  grpc_call_credentials base;
+  grpc_call_credentials_array inner;
+} grpc_composite_call_credentials;
 
 /* -- Plugin credentials. -- */
 
 typedef struct {
-  grpc_credentials base;
+  grpc_call_credentials base;
   grpc_metadata_credentials_plugin plugin;
   grpc_credentials_md_store *plugin_md;
 } grpc_plugin_credentials;
diff --git a/src/core/security/google_default_credentials.c b/src/core/security/google_default_credentials.c
index 45135305b2..6a54fe4e47 100644
--- a/src/core/security/google_default_credentials.c
+++ b/src/core/security/google_default_credentials.c
@@ -50,7 +50,7 @@
 
 /* -- Default credentials. -- */
 
-static grpc_credentials *default_credentials = NULL;
+static grpc_channel_credentials *default_credentials = NULL;
 static int compute_engine_detection_done = 0;
 static gpr_mu g_mu;
 static gpr_once g_once = GPR_ONCE_INIT;
@@ -138,11 +138,11 @@ static int is_stack_running_on_compute_engine(void) {
 }
 
 /* Takes ownership of creds_path if not NULL. */
-static grpc_credentials *create_default_creds_from_path(char *creds_path) {
+static grpc_call_credentials *create_default_creds_from_path(char *creds_path) {
   grpc_json *json = NULL;
   grpc_auth_json_key key;
   grpc_auth_refresh_token token;
-  grpc_credentials *result = NULL;
+  grpc_call_credentials *result = NULL;
   gpr_slice creds_data = gpr_empty_slice();
   int file_ok = 0;
   if (creds_path == NULL) goto end;
@@ -176,9 +176,9 @@ end:
   return result;
 }
 
-grpc_credentials *grpc_google_default_credentials_create(void) {
-  grpc_credentials *result = NULL;
-  int serving_cached_credentials = 0;
+grpc_channel_credentials *grpc_google_default_credentials_create(void) {
+  grpc_channel_credentials *result = NULL;
+  grpc_call_credentials *call_creds = NULL;
 
   GRPC_API_TRACE("grpc_google_default_credentials_create(void)", 0, ());
 
@@ -187,20 +187,19 @@ grpc_credentials *grpc_google_default_credentials_create(void) {
   gpr_mu_lock(&g_mu);
 
   if (default_credentials != NULL) {
-    result = grpc_credentials_ref(default_credentials);
-    serving_cached_credentials = 1;
+    result = grpc_channel_credentials_ref(default_credentials);
     goto end;
   }
 
   /* First, try the environment variable. */
-  result = create_default_creds_from_path(
+  call_creds = create_default_creds_from_path(
       gpr_getenv(GRPC_GOOGLE_CREDENTIALS_ENV_VAR));
-  if (result != NULL) goto end;
+  if (call_creds != NULL) goto end;
 
   /* Then the well-known file. */
-  result = create_default_creds_from_path(
+  call_creds = create_default_creds_from_path(
       grpc_get_well_known_google_credentials_file_path());
-  if (result != NULL) goto end;
+  if (call_creds != NULL) goto end;
 
   /* At last try to see if we're on compute engine (do the detection only once
      since it requires a network test). */
@@ -208,21 +207,28 @@ grpc_credentials *grpc_google_default_credentials_create(void) {
     int need_compute_engine_creds = is_stack_running_on_compute_engine();
     compute_engine_detection_done = 1;
     if (need_compute_engine_creds) {
-      result = grpc_google_compute_engine_credentials_create(NULL);
+      call_creds = grpc_google_compute_engine_credentials_create(NULL);
     }
   }
 
 end:
-  if (!serving_cached_credentials && result != NULL) {
-    /* Blend with default ssl credentials and add a global reference so that it
-       can be cached and re-served. */
-    grpc_credentials *ssl_creds = grpc_ssl_credentials_create(NULL, NULL, NULL);
-    default_credentials = grpc_credentials_ref(
-        grpc_composite_credentials_create(ssl_creds, result, NULL));
-    GPR_ASSERT(default_credentials != NULL);
-    grpc_credentials_unref(ssl_creds);
-    grpc_credentials_unref(result);
-    result = default_credentials;
+  if (result == NULL) {
+    if (call_creds != NULL) {
+      /* Blend with default ssl credentials and add a global reference so that
+         it
+         can be cached and re-served. */
+      grpc_channel_credentials *ssl_creds =
+          grpc_ssl_credentials_create(NULL, NULL, NULL);
+      default_credentials = grpc_channel_credentials_ref(
+          grpc_composite_channel_credentials_create(ssl_creds, call_creds,
+                                                    NULL));
+      GPR_ASSERT(default_credentials != NULL);
+      grpc_channel_credentials_unref(ssl_creds);
+      grpc_call_credentials_unref(call_creds);
+      result = default_credentials;
+    } else {
+      gpr_log(GPR_ERROR, "Could not create google default credentials.");
+    }
   }
   gpr_mu_unlock(&g_mu);
   return result;
@@ -232,7 +238,7 @@ void grpc_flush_cached_google_default_credentials(void) {
   gpr_once_init(&g_once, init_default_credentials);
   gpr_mu_lock(&g_mu);
   if (default_credentials != NULL) {
-    grpc_credentials_unref(default_credentials);
+    grpc_channel_credentials_unref(default_credentials);
     default_credentials = NULL;
   }
   gpr_mu_unlock(&g_mu);
diff --git a/src/core/security/security_connector.c b/src/core/security/security_connector.c
index 7c4cf6f04d..3c54a4deae 100644
--- a/src/core/security/security_connector.c
+++ b/src/core/security/security_connector.c
@@ -203,16 +203,6 @@ grpc_security_connector *grpc_find_security_connector_in_args(
   return NULL;
 }
 
-static int check_request_metadata_creds(grpc_credentials *creds) {
-  if (creds != NULL && !grpc_credentials_has_request_metadata(creds)) {
-    gpr_log(GPR_ERROR,
-            "Incompatible credentials for channel security connector: needs to "
-            "set request metadata.");
-    return 0;
-  }
-  return 1;
-}
-
 /* -- Fake implementation. -- */
 
 typedef struct {
@@ -222,7 +212,7 @@ typedef struct {
 
 static void fake_channel_destroy(grpc_security_connector *sc) {
   grpc_channel_security_connector *c = (grpc_channel_security_connector *)sc;
-  grpc_credentials_unref(c->request_metadata_creds);
+  grpc_call_credentials_unref(c->request_metadata_creds);
   GRPC_AUTH_CONTEXT_UNREF(sc->auth_context, "connector");
   gpr_free(sc);
 }
@@ -306,7 +296,8 @@ static grpc_security_connector_vtable fake_server_vtable = {
     fake_server_destroy, fake_server_do_handshake, fake_check_peer};
 
 grpc_channel_security_connector *grpc_fake_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, int call_host_check_is_async) {
+    grpc_call_credentials *request_metadata_creds,
+    int call_host_check_is_async) {
   grpc_fake_channel_security_connector *c =
       gpr_malloc(sizeof(grpc_fake_channel_security_connector));
   memset(c, 0, sizeof(grpc_fake_channel_security_connector));
@@ -314,8 +305,8 @@ grpc_channel_security_connector *grpc_fake_channel_security_connector_create(
   c->base.base.is_client_side = 1;
   c->base.base.url_scheme = GRPC_FAKE_SECURITY_URL_SCHEME;
   c->base.base.vtable = &fake_channel_vtable;
-  GPR_ASSERT(check_request_metadata_creds(request_metadata_creds));
-  c->base.request_metadata_creds = grpc_credentials_ref(request_metadata_creds);
+  c->base.request_metadata_creds =
+      grpc_call_credentials_ref(request_metadata_creds);
   c->base.check_call_host = fake_channel_check_call_host;
   c->call_host_check_is_async = call_host_check_is_async;
   return &c->base;
@@ -349,7 +340,7 @@ typedef struct {
 static void ssl_channel_destroy(grpc_security_connector *sc) {
   grpc_ssl_channel_security_connector *c =
       (grpc_ssl_channel_security_connector *)sc;
-  grpc_credentials_unref(c->base.request_metadata_creds);
+  grpc_call_credentials_unref(c->base.request_metadata_creds);
   if (c->handshaker_factory != NULL) {
     tsi_ssl_handshaker_factory_destroy(c->handshaker_factory);
   }
@@ -580,9 +571,9 @@ size_t grpc_get_default_ssl_roots(const unsigned char **pem_root_certs) {
 }
 
 grpc_security_status grpc_ssl_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, const grpc_ssl_config *config,
-    const char *target_name, const char *overridden_target_name,
-    grpc_channel_security_connector **sc) {
+    grpc_call_credentials *request_metadata_creds,
+    const grpc_ssl_config *config, const char *target_name,
+    const char *overridden_target_name, grpc_channel_security_connector **sc) {
   size_t num_alpn_protocols = grpc_chttp2_num_alpn_versions();
   const unsigned char **alpn_protocol_strings =
       gpr_malloc(sizeof(const char *) * num_alpn_protocols);
@@ -606,9 +597,6 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
     gpr_log(GPR_ERROR, "An ssl channel needs a config and a target name.");
     goto error;
   }
-  if (!check_request_metadata_creds(request_metadata_creds)) {
-    goto error;
-  }
   if (config->pem_root_certs == NULL) {
     pem_root_certs_size = grpc_get_default_ssl_roots(&pem_root_certs);
     if (pem_root_certs == NULL || pem_root_certs_size == 0) {
@@ -627,7 +615,8 @@ grpc_security_status grpc_ssl_channel_security_connector_create(
   c->base.base.vtable = &ssl_channel_vtable;
   c->base.base.is_client_side = 1;
   c->base.base.url_scheme = GRPC_SSL_URL_SCHEME;
-  c->base.request_metadata_creds = grpc_credentials_ref(request_metadata_creds);
+  c->base.request_metadata_creds =
+      grpc_call_credentials_ref(request_metadata_creds);
   c->base.check_call_host = ssl_channel_check_call_host;
   gpr_split_host_port(target_name, &c->target_name, &port);
   gpr_free(port);
diff --git a/src/core/security/security_connector.h b/src/core/security/security_connector.h
index 9218a3caab..c5f00c5563 100644
--- a/src/core/security/security_connector.h
+++ b/src/core/security/security_connector.h
@@ -145,7 +145,7 @@ typedef struct grpc_channel_security_connector grpc_channel_security_connector;
 
 struct grpc_channel_security_connector {
   grpc_security_connector base; /* requires is_client_side to be non 0. */
-  grpc_credentials *request_metadata_creds;
+  grpc_call_credentials *request_metadata_creds;
   grpc_security_status (*check_call_host)(grpc_exec_ctx *exec_ctx,
                                           grpc_channel_security_connector *sc,
                                           const char *host,
@@ -167,7 +167,8 @@ grpc_security_status grpc_channel_security_connector_check_call_host(
 /* For TESTING ONLY!
    Creates a fake connector that emulates real channel security.  */
 grpc_channel_security_connector *grpc_fake_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, int call_host_check_is_async);
+    grpc_call_credentials *request_metadata_creds,
+    int call_host_check_is_async);
 
 /* For TESTING ONLY!
    Creates a fake connector that emulates real server security.  */
@@ -197,9 +198,9 @@ typedef struct {
   specific error code otherwise.
 */
 grpc_security_status grpc_ssl_channel_security_connector_create(
-    grpc_credentials *request_metadata_creds, const grpc_ssl_config *config,
-    const char *target_name, const char *overridden_target_name,
-    grpc_channel_security_connector **sc);
+    grpc_call_credentials *request_metadata_creds,
+    const grpc_ssl_config *config, const char *target_name,
+    const char *overridden_target_name, grpc_channel_security_connector **sc);
 
 /* Gets the default ssl roots. */
 size_t grpc_get_default_ssl_roots(const unsigned char **pem_root_certs);
diff --git a/src/core/security/security_context.c b/src/core/security/security_context.c
index ff3ad64d92..2068c97d78 100644
--- a/src/core/security/security_context.c
+++ b/src/core/security/security_context.c
@@ -46,7 +46,7 @@
 /* --- grpc_call --- */
 
 grpc_call_error grpc_call_set_credentials(grpc_call *call,
-                                          grpc_credentials *creds) {
+                                          grpc_call_credentials *creds) {
   grpc_client_security_context *ctx = NULL;
   GRPC_API_TRACE("grpc_call_set_credentials(call=%p, creds=%p)", 2,
                  (call, creds));
@@ -54,20 +54,16 @@ grpc_call_error grpc_call_set_credentials(grpc_call *call,
     gpr_log(GPR_ERROR, "Method is client-side only.");
     return GRPC_CALL_ERROR_NOT_ON_SERVER;
   }
-  if (creds != NULL && !grpc_credentials_has_request_metadata_only(creds)) {
-    gpr_log(GPR_ERROR, "Incompatible credentials to set on a call.");
-    return GRPC_CALL_ERROR;
-  }
   ctx = (grpc_client_security_context *)grpc_call_context_get(
       call, GRPC_CONTEXT_SECURITY);
   if (ctx == NULL) {
     ctx = grpc_client_security_context_create();
-    ctx->creds = grpc_credentials_ref(creds);
+    ctx->creds = grpc_call_credentials_ref(creds);
     grpc_call_context_set(call, GRPC_CONTEXT_SECURITY, ctx,
                           grpc_client_security_context_destroy);
   } else {
-    grpc_credentials_unref(ctx->creds);
-    ctx->creds = grpc_credentials_ref(creds);
+    grpc_call_credentials_unref(ctx->creds);
+    ctx->creds = grpc_call_credentials_ref(creds);
   }
   return GRPC_CALL_OK;
 }
@@ -101,7 +97,7 @@ grpc_client_security_context *grpc_client_security_context_create(void) {
 
 void grpc_client_security_context_destroy(void *ctx) {
   grpc_client_security_context *c = (grpc_client_security_context *)ctx;
-  grpc_credentials_unref(c->creds);
+  grpc_call_credentials_unref(c->creds);
   GRPC_AUTH_CONTEXT_UNREF(c->auth_context, "client_security_context");
   gpr_free(ctx);
 }
diff --git a/src/core/security/security_context.h b/src/core/security/security_context.h
index 2bbdc4be97..794258edbc 100644
--- a/src/core/security/security_context.h
+++ b/src/core/security/security_context.h
@@ -85,7 +85,7 @@ void grpc_auth_property_reset(grpc_auth_property *property);
    Internal client-side security context. */
 
 typedef struct {
-  grpc_credentials *creds;
+  grpc_call_credentials *creds;
   grpc_auth_context *auth_context;
 } grpc_client_security_context;
 
diff --git a/src/core/security/server_secure_chttp2.c b/src/core/security/server_secure_chttp2.c
index 851e0cfab3..1ea269bf8f 100644
--- a/src/core/security/server_secure_chttp2.c
+++ b/src/core/security/server_secure_chttp2.c
@@ -249,9 +249,11 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
   }
 
   for (i = 0; i < resolved->naddrs; i++) {
-    port_temp = grpc_tcp_server_add_port(
+    grpc_tcp_listener *listener;
+    listener = grpc_tcp_server_add_port(
         tcp, (struct sockaddr *)&resolved->addrs[i].addr,
         resolved->addrs[i].len);
+    port_temp = grpc_tcp_listener_get_port(listener);
     if (port_temp >= 0) {
       if (port_num == -1) {
         port_num = port_temp;
diff --git a/src/core/support/slice_buffer.c b/src/core/support/slice_buffer.c
index 17c0b6c0f6..856d3a2439 100644
--- a/src/core/support/slice_buffer.c
+++ b/src/core/support/slice_buffer.c
@@ -220,7 +220,7 @@ void gpr_slice_buffer_move_first(gpr_slice_buffer *src, size_t n,
     return;
   }
   src_idx = 0;
-  for (;;) {
+  while (src_idx < src->capacity) {
     gpr_slice slice = src->slices[src_idx];
     size_t slice_len = GPR_SLICE_LENGTH(slice);
     if (n > slice_len) {
diff --git a/src/core/support/time_win32.c b/src/core/support/time_win32.c
index bc0586d069..623a8d9233 100644
--- a/src/core/support/time_win32.c
+++ b/src/core/support/time_win32.c
@@ -66,14 +66,12 @@ gpr_timespec gpr_now(gpr_clock_type clock) {
       now_tv.tv_nsec = now_tb.millitm * 1000000;
       break;
     case GPR_CLOCK_MONOTONIC:
+    case GPR_CLOCK_PRECISE:
       QueryPerformanceCounter(&timestamp);
       now_dbl = (timestamp.QuadPart - g_start_time.QuadPart) * g_time_scale;
       now_tv.tv_sec = (time_t)now_dbl;
       now_tv.tv_nsec = (int)((now_dbl - (double)now_tv.tv_sec) * 1e9);
       break;
-    case GPR_CLOCK_PRECISE:
-      gpr_precise_clock_now(&now_tv);
-      break;
   }
   return now_tv;
 }
diff --git a/src/core/surface/byte_buffer_reader.c b/src/core/surface/byte_buffer_reader.c
index 9f830df68c..57417f41b0 100644
--- a/src/core/surface/byte_buffer_reader.c
+++ b/src/core/surface/byte_buffer_reader.c
@@ -121,4 +121,3 @@ gpr_slice grpc_byte_buffer_reader_readall(grpc_byte_buffer_reader *reader) {
   }
   return out_slice;
 }
-
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index aa435d44d3..86d5fca388 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -922,7 +922,8 @@ static batch_control *allocate_batch_control(grpc_call *call) {
   size_t i;
   for (i = 0; i < MAX_CONCURRENT_BATCHES; i++) {
     if ((call->used_batches & (1 << i)) == 0) {
-      call->used_batches |= (gpr_uint8)(1 << i);
+      call->used_batches =
+          (gpr_uint8)(call->used_batches | (gpr_uint8)(1 << i));
       return &call->active_batches[i];
     }
   }
diff --git a/src/core/surface/secure_channel_create.c b/src/core/surface/secure_channel_create.c
index 1282ee99ed..0dd0a31169 100644
--- a/src/core/surface/secure_channel_create.c
+++ b/src/core/surface/secure_channel_create.c
@@ -230,7 +230,7 @@ static const grpc_subchannel_factory_vtable subchannel_factory_vtable = {
    Asynchronously: - resolve target
                    - connect to it (trying alternatives as presented)
                    - perform handshakes */
-grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
+grpc_channel *grpc_secure_channel_create(grpc_channel_credentials *creds,
                                          const char *target,
                                          const grpc_channel_args *args,
                                          void *reserved) {
@@ -261,9 +261,9 @@ grpc_channel *grpc_secure_channel_create(grpc_credentials *creds,
         "Security connector exists in channel args.");
   }
 
-  if (grpc_credentials_create_security_connector(
-          creds, target, args, NULL, &security_connector,
-          &new_args_from_connector) != GRPC_SECURITY_OK) {
+  if (grpc_channel_credentials_create_security_connector(
+          creds, target, args, &security_connector, &new_args_from_connector) !=
+      GRPC_SECURITY_OK) {
     grpc_exec_ctx_finish(&exec_ctx);
     return grpc_lame_client_channel_create(
         target, GRPC_STATUS_INVALID_ARGUMENT,
diff --git a/src/core/surface/server_chttp2.c b/src/core/surface/server_chttp2.c
index 580b91573c..1408f9c159 100644
--- a/src/core/surface/server_chttp2.c
+++ b/src/core/surface/server_chttp2.c
@@ -107,9 +107,11 @@ int grpc_server_add_insecure_http2_port(grpc_server *server, const char *addr) {
   }
 
   for (i = 0; i < resolved->naddrs; i++) {
-    port_temp = grpc_tcp_server_add_port(
+    grpc_tcp_listener *listener;
+    listener = grpc_tcp_server_add_port(
         tcp, (struct sockaddr *)&resolved->addrs[i].addr,
         resolved->addrs[i].len);
+    port_temp = grpc_tcp_listener_get_port(listener);
     if (port_temp >= 0) {
       if (port_num == -1) {
         port_num = port_temp;
diff --git a/src/core/surface/version.c b/src/core/surface/version.c
index e559d51448..962a72112a 100644
--- a/src/core/surface/version.c
+++ b/src/core/surface/version.c
@@ -36,4 +36,4 @@
 
 #include <grpc/grpc.h>
 
-const char *grpc_version_string(void) { return "0.11.0.0"; }
+const char *grpc_version_string(void) { return "0.12.0.0"; }
diff --git a/src/core/transport/chttp2/hpack_encoder.c b/src/core/transport/chttp2/hpack_encoder.c
index 6c7c00b7c3..758babc3d0 100644
--- a/src/core/transport/chttp2/hpack_encoder.c
+++ b/src/core/transport/chttp2/hpack_encoder.c
@@ -36,8 +36,10 @@
 #include <assert.h>
 #include <string.h>
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 #include <grpc/support/useful.h>
+
 #include "src/core/transport/chttp2/bin_encoder.h"
 #include "src/core/transport/chttp2/hpack_table.h"
 #include "src/core/transport/chttp2/timeout_encoding.h"
@@ -154,6 +156,18 @@ static gpr_uint8 *add_tiny_header_data(framer_state *st, size_t len) {
   return gpr_slice_buffer_tiny_add(st->output, len);
 }
 
+static void evict_entry(grpc_chttp2_hpack_compressor *c) {
+  c->tail_remote_index++;
+  GPR_ASSERT(c->tail_remote_index > 0);
+  GPR_ASSERT(c->table_size >=
+             c->table_elem_size[c->tail_remote_index % c->cap_table_elems]);
+  GPR_ASSERT(c->table_elems > 0);
+  c->table_size = (gpr_uint16)(
+      c->table_size -
+      c->table_elem_size[c->tail_remote_index % c->cap_table_elems]);
+  c->table_elems--;
+}
+
 /* add an element to the decoder table */
 static void add_elem(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem) {
   gpr_uint32 key_hash = elem->key->hash;
@@ -164,26 +178,21 @@ static void add_elem(grpc_chttp2_hpack_compressor *c, grpc_mdelem *elem) {
 
   GPR_ASSERT(elem_size < 65536);
 
+  if (elem_size > c->max_table_size) {
+    while (c->table_size > 0) {
+      evict_entry(c);
+    }
+    return;
+  }
+
   /* Reserve space for this element in the remote table: if this overflows
      the current table, drop elements until it fits, matching the decompressor
      algorithm */
-  /* TODO(ctiller): constant */
-  while (c->table_size + elem_size > 4096) {
-    c->tail_remote_index++;
-    GPR_ASSERT(c->tail_remote_index > 0);
-    GPR_ASSERT(c->table_size >=
-               c->table_elem_size[c->tail_remote_index %
-                                  GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS]);
-    GPR_ASSERT(c->table_elems > 0);
-    c->table_size =
-        (gpr_uint16)(c->table_size -
-                     c->table_elem_size[c->tail_remote_index %
-                                        GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS]);
-    c->table_elems--;
+  while (c->table_size + elem_size > c->max_table_size) {
+    evict_entry(c);
   }
-  GPR_ASSERT(c->table_elems < GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS);
-  c->table_elem_size[new_index % GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS] =
-      (gpr_uint16)elem_size;
+  GPR_ASSERT(c->table_elems < c->max_table_size);
+  c->table_elem_size[new_index % c->cap_table_elems] = (gpr_uint16)elem_size;
   c->table_size = (gpr_uint16)(c->table_size + elem_size);
   c->table_elems++;
 
@@ -329,6 +338,14 @@ static void emit_lithdr_noidx_v(grpc_chttp2_hpack_compressor *c,
   add_header_data(st, gpr_slice_ref(value_slice));
 }
 
+static void emit_advertise_table_size_change(grpc_chttp2_hpack_compressor *c,
+                                             framer_state *st) {
+  gpr_uint32 len = GRPC_CHTTP2_VARINT_LENGTH(c->max_table_size, 3);
+  GRPC_CHTTP2_WRITE_VARINT(c->max_table_size, 3, 0x20,
+                           add_tiny_header_data(st, len), len);
+  c->advertise_table_size_change = 0;
+}
+
 static gpr_uint32 dynidx(grpc_chttp2_hpack_compressor *c,
                          gpr_uint32 elem_index) {
   return 1 + GRPC_CHTTP2_LAST_STATIC_ENTRY + c->tail_remote_index +
@@ -447,11 +464,23 @@ gpr_slice grpc_chttp2_data_frame_create_empty_close(gpr_uint32 id) {
   return slice;
 }
 
+static gpr_uint32 elems_for_bytes(gpr_uint32 bytes) {
+  return (bytes + 31) / 32;
+}
+
 void grpc_chttp2_hpack_compressor_init(grpc_chttp2_hpack_compressor *c,
                                        grpc_mdctx *ctx) {
   memset(c, 0, sizeof(*c));
   c->mdctx = ctx;
   c->timeout_key_str = grpc_mdstr_from_string(ctx, "grpc-timeout");
+  c->max_table_size = GRPC_CHTTP2_HPACKC_INITIAL_TABLE_SIZE;
+  c->cap_table_elems = elems_for_bytes(c->max_table_size);
+  c->max_table_elems = c->cap_table_elems;
+  c->max_usable_size = GRPC_CHTTP2_HPACKC_INITIAL_TABLE_SIZE;
+  c->table_elem_size =
+      gpr_malloc(sizeof(*c->table_elem_size) * c->cap_table_elems);
+  memset(c->table_elem_size, 0,
+         sizeof(*c->table_elem_size) * c->cap_table_elems);
 }
 
 void grpc_chttp2_hpack_compressor_destroy(grpc_chttp2_hpack_compressor *c) {
@@ -461,6 +490,54 @@ void grpc_chttp2_hpack_compressor_destroy(grpc_chttp2_hpack_compressor *c) {
     if (c->entries_elems[i]) GRPC_MDELEM_UNREF(c->entries_elems[i]);
   }
   GRPC_MDSTR_UNREF(c->timeout_key_str);
+  gpr_free(c->table_elem_size);
+}
+
+void grpc_chttp2_hpack_compressor_set_max_usable_size(
+    grpc_chttp2_hpack_compressor *c, gpr_uint32 max_table_size) {
+  c->max_usable_size = max_table_size;
+  grpc_chttp2_hpack_compressor_set_max_table_size(
+      c, GPR_MIN(c->max_table_size, max_table_size));
+}
+
+static void rebuild_elems(grpc_chttp2_hpack_compressor *c, gpr_uint32 new_cap) {
+  gpr_uint16 *table_elem_size = gpr_malloc(sizeof(*table_elem_size) * new_cap);
+  gpr_uint32 i;
+
+  memset(table_elem_size, 0, sizeof(*table_elem_size) * new_cap);
+  GPR_ASSERT(c->table_elems <= new_cap);
+
+  for (i = 0; i < c->table_elems; i++) {
+    gpr_uint32 ofs = c->tail_remote_index + i + 1;
+    table_elem_size[ofs % new_cap] = c->table_elem_size[ofs % c->cap_table_elems];
+  }
+
+  c->cap_table_elems = new_cap;
+  gpr_free(c->table_elem_size);
+  c->table_elem_size = table_elem_size;
+}
+
+void grpc_chttp2_hpack_compressor_set_max_table_size(
+    grpc_chttp2_hpack_compressor *c, gpr_uint32 max_table_size) {
+  max_table_size = GPR_MIN(max_table_size, c->max_usable_size);
+  if (max_table_size == c->max_table_size) {
+    return;
+  }
+  while (c->table_size > 0 && c->table_size > max_table_size) {
+    evict_entry(c);
+  }
+  c->max_table_size = max_table_size;
+  c->max_table_elems = elems_for_bytes(max_table_size);
+  if (c->max_table_elems > c->cap_table_elems) {
+    rebuild_elems(c, GPR_MAX(c->max_table_elems, 2 * c->cap_table_elems));
+  } else if (c->max_table_elems < c->cap_table_elems / 3) {
+    gpr_uint32 new_cap = GPR_MAX(c->max_table_elems, 16);
+    if (new_cap != c->cap_table_elems) {
+      rebuild_elems(c, new_cap);
+    }
+  }
+  c->advertise_table_size_change = 1;
+  gpr_log(GPR_DEBUG, "set max table size from encoder to %d", max_table_size);
 }
 
 void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c,
@@ -483,6 +560,9 @@ void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c,
      slot. THIS MAY NOT BE THE SAME ELEMENT (if a decoder table slot got
      updated). After this loop, we'll do a batch unref of elements. */
   begin_frame(&st);
+  if (c->advertise_table_size_change != 0) {
+    emit_advertise_table_size_change(c, &st);
+  }
   grpc_metadata_batch_assert_ok(metadata);
   for (l = metadata->list.head; l; l = l->next) {
     hpack_enc(c, l->md, &st);
diff --git a/src/core/transport/chttp2/hpack_encoder.h b/src/core/transport/chttp2/hpack_encoder.h
index 59b122dfda..ce83d101f2 100644
--- a/src/core/transport/chttp2/hpack_encoder.h
+++ b/src/core/transport/chttp2/hpack_encoder.h
@@ -43,14 +43,26 @@
 
 #define GRPC_CHTTP2_HPACKC_NUM_FILTERS 256
 #define GRPC_CHTTP2_HPACKC_NUM_VALUES 256
-#define GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS (4096 / 32)
+/* initial table size, per spec */
+#define GRPC_CHTTP2_HPACKC_INITIAL_TABLE_SIZE 4096
+/* maximum table size we'll actually use */
+#define GRPC_CHTTP2_HPACKC_MAX_TABLE_SIZE (1024 * 1024)
 
 typedef struct {
   gpr_uint32 filter_elems_sum;
+  gpr_uint32 max_table_size;
+  gpr_uint32 max_table_elems;
+  gpr_uint32 cap_table_elems;
+  /** if non-zero, advertise to the decoder that we'll start using a table
+      of this size */
+  gpr_uint8 advertise_table_size_change;
+  /** maximum number of bytes we'll use for the decode table (to guard against
+      peers ooming us by setting decode table size high) */
+  gpr_uint32 max_usable_size;
   /* one before the lowest usable table index */
   gpr_uint32 tail_remote_index;
-  gpr_uint16 table_size;
-  gpr_uint16 table_elems;
+  gpr_uint32 table_size;
+  gpr_uint32 table_elems;
 
   /* filter tables for elems: this tables provides an approximate
      popularity count for particular hashes, and are used to determine whether
@@ -71,12 +83,16 @@ typedef struct {
   gpr_uint32 indices_keys[GRPC_CHTTP2_HPACKC_NUM_VALUES];
   gpr_uint32 indices_elems[GRPC_CHTTP2_HPACKC_NUM_VALUES];
 
-  gpr_uint16 table_elem_size[GRPC_CHTTP2_HPACKC_MAX_TABLE_ELEMS];
+  gpr_uint16 *table_elem_size;
 } grpc_chttp2_hpack_compressor;
 
 void grpc_chttp2_hpack_compressor_init(grpc_chttp2_hpack_compressor *c,
                                        grpc_mdctx *mdctx);
 void grpc_chttp2_hpack_compressor_destroy(grpc_chttp2_hpack_compressor *c);
+void grpc_chttp2_hpack_compressor_set_max_table_size(
+    grpc_chttp2_hpack_compressor *c, gpr_uint32 max_table_size);
+void grpc_chttp2_hpack_compressor_set_max_usable_size(
+    grpc_chttp2_hpack_compressor *c, gpr_uint32 max_table_size);
 
 void grpc_chttp2_encode_header(grpc_chttp2_hpack_compressor *c, gpr_uint32 id,
                                grpc_metadata_batch *metadata, int is_eof,
diff --git a/src/core/transport/chttp2/hpack_parser.c b/src/core/transport/chttp2/hpack_parser.c
index 6eebfc3ce4..57a3a20b1d 100644
--- a/src/core/transport/chttp2/hpack_parser.c
+++ b/src/core/transport/chttp2/hpack_parser.c
@@ -74,6 +74,8 @@ static int parse_begin(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
                        const gpr_uint8 *end);
 static int parse_error(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
                        const gpr_uint8 *end);
+static int parse_illegal_op(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
+                            const gpr_uint8 *end);
 
 static int parse_string_prefix(grpc_chttp2_hpack_parser *p,
                                const gpr_uint8 *cur, const gpr_uint8 *end);
@@ -156,7 +158,7 @@ static const grpc_chttp2_hpack_parser_state first_byte_action[] = {
     parse_lithdr_incidx_x, parse_lithdr_incidx_v, parse_lithdr_notidx,
     parse_lithdr_notidx_x, parse_lithdr_notidx_v, parse_lithdr_nvridx,
     parse_lithdr_nvridx_x, parse_lithdr_nvridx_v, parse_max_tbl_size,
-    parse_max_tbl_size_x,  parse_error};
+    parse_max_tbl_size_x,  parse_illegal_op};
 
 /* indexes the first byte to a parse state function - generated by
    gen_hpack_tables.c */
@@ -169,7 +171,7 @@ static const gpr_uint8 first_byte_lut[256] = {
     LITHDR_NVRIDX,   LITHDR_NVRIDX, LITHDR_NVRIDX, LITHDR_NVRIDX,
     LITHDR_NVRIDX,   LITHDR_NVRIDX, LITHDR_NVRIDX, LITHDR_NVRIDX,
     LITHDR_NVRIDX,   LITHDR_NVRIDX, LITHDR_NVRIDX, LITHDR_NVRIDX_X,
-    ILLEGAL,         MAX_TBL_SIZE,  MAX_TBL_SIZE,  MAX_TBL_SIZE,
+    MAX_TBL_SIZE,    MAX_TBL_SIZE,  MAX_TBL_SIZE,  MAX_TBL_SIZE,
     MAX_TBL_SIZE,    MAX_TBL_SIZE,  MAX_TBL_SIZE,  MAX_TBL_SIZE,
     MAX_TBL_SIZE,    MAX_TBL_SIZE,  MAX_TBL_SIZE,  MAX_TBL_SIZE,
     MAX_TBL_SIZE,    MAX_TBL_SIZE,  MAX_TBL_SIZE,  MAX_TBL_SIZE,
@@ -622,13 +624,15 @@ static const gpr_uint8 inverse_base64[256] = {
 };
 
 /* emission helpers */
-static void on_hdr(grpc_chttp2_hpack_parser *p, grpc_mdelem *md,
-                   int add_to_table) {
+static int on_hdr(grpc_chttp2_hpack_parser *p, grpc_mdelem *md,
+                  int add_to_table) {
   if (add_to_table) {
-    GRPC_MDELEM_REF(md);
-    grpc_chttp2_hptbl_add(&p->table, md);
+    if (!grpc_chttp2_hptbl_add(&p->table, md)) {
+      return 0;
+    }
   }
   p->on_header(p->on_header_user_data, md);
+  return 1;
 }
 
 static grpc_mdstr *take_string(grpc_chttp2_hpack_parser *p,
@@ -714,9 +718,12 @@ static int parse_stream_dep0(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
 static int finish_indexed_field(grpc_chttp2_hpack_parser *p,
                                 const gpr_uint8 *cur, const gpr_uint8 *end) {
   grpc_mdelem *md = grpc_chttp2_hptbl_lookup(&p->table, p->index);
+  if (md == NULL) {
+    gpr_log(GPR_ERROR, "Invalid HPACK index received: %d", p->index);
+    return 0;
+  }
   GRPC_MDELEM_REF(md);
-  on_hdr(p, md, 0);
-  return parse_begin(p, cur, end);
+  return on_hdr(p, md, 0) && parse_begin(p, cur, end);
 }
 
 /* parse an indexed field with index < 127 */
@@ -742,21 +749,21 @@ static int parse_indexed_field_x(grpc_chttp2_hpack_parser *p,
 static int finish_lithdr_incidx(grpc_chttp2_hpack_parser *p,
                                 const gpr_uint8 *cur, const gpr_uint8 *end) {
   grpc_mdelem *md = grpc_chttp2_hptbl_lookup(&p->table, p->index);
-  on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
-                                              GRPC_MDSTR_REF(md->key),
-                                              take_string(p, &p->value)),
-         1);
-  return parse_begin(p, cur, end);
+  return on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
+                                                     GRPC_MDSTR_REF(md->key),
+                                                     take_string(p, &p->value)),
+                1) &&
+         parse_begin(p, cur, end);
 }
 
 /* finish a literal header with incremental indexing with no index */
 static int finish_lithdr_incidx_v(grpc_chttp2_hpack_parser *p,
                                   const gpr_uint8 *cur, const gpr_uint8 *end) {
-  on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
-                                              take_string(p, &p->key),
-                                              take_string(p, &p->value)),
-         1);
-  return parse_begin(p, cur, end);
+  return on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
+                                                     take_string(p, &p->key),
+                                                     take_string(p, &p->value)),
+                1) &&
+         parse_begin(p, cur, end);
 }
 
 /* parse a literal header with incremental indexing; index < 63 */
@@ -795,21 +802,21 @@ static int parse_lithdr_incidx_v(grpc_chttp2_hpack_parser *p,
 static int finish_lithdr_notidx(grpc_chttp2_hpack_parser *p,
                                 const gpr_uint8 *cur, const gpr_uint8 *end) {
   grpc_mdelem *md = grpc_chttp2_hptbl_lookup(&p->table, p->index);
-  on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
-                                              GRPC_MDSTR_REF(md->key),
-                                              take_string(p, &p->value)),
-         0);
-  return parse_begin(p, cur, end);
+  return on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
+                                                     GRPC_MDSTR_REF(md->key),
+                                                     take_string(p, &p->value)),
+                0) &&
+         parse_begin(p, cur, end);
 }
 
 /* finish a literal header without incremental indexing with index = 0 */
 static int finish_lithdr_notidx_v(grpc_chttp2_hpack_parser *p,
                                   const gpr_uint8 *cur, const gpr_uint8 *end) {
-  on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
-                                              take_string(p, &p->key),
-                                              take_string(p, &p->value)),
-         0);
-  return parse_begin(p, cur, end);
+  return on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
+                                                     take_string(p, &p->key),
+                                                     take_string(p, &p->value)),
+                0) &&
+         parse_begin(p, cur, end);
 }
 
 /* parse a literal header without incremental indexing; index < 15 */
@@ -848,21 +855,21 @@ static int parse_lithdr_notidx_v(grpc_chttp2_hpack_parser *p,
 static int finish_lithdr_nvridx(grpc_chttp2_hpack_parser *p,
                                 const gpr_uint8 *cur, const gpr_uint8 *end) {
   grpc_mdelem *md = grpc_chttp2_hptbl_lookup(&p->table, p->index);
-  on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
-                                              GRPC_MDSTR_REF(md->key),
-                                              take_string(p, &p->value)),
-         0);
-  return parse_begin(p, cur, end);
+  return on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
+                                                     GRPC_MDSTR_REF(md->key),
+                                                     take_string(p, &p->value)),
+                0) &&
+         parse_begin(p, cur, end);
 }
 
 /* finish a literal header that is never indexed with an extra value */
 static int finish_lithdr_nvridx_v(grpc_chttp2_hpack_parser *p,
                                   const gpr_uint8 *cur, const gpr_uint8 *end) {
-  on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
-                                              take_string(p, &p->key),
-                                              take_string(p, &p->value)),
-         0);
-  return parse_begin(p, cur, end);
+  return on_hdr(p, grpc_mdelem_from_metadata_strings(p->table.mdctx,
+                                                     take_string(p, &p->key),
+                                                     take_string(p, &p->value)),
+                0) &&
+         parse_begin(p, cur, end);
 }
 
 /* parse a literal header that is never indexed; index < 15 */
@@ -901,14 +908,14 @@ static int parse_lithdr_nvridx_v(grpc_chttp2_hpack_parser *p,
 static int finish_max_tbl_size(grpc_chttp2_hpack_parser *p,
                                const gpr_uint8 *cur, const gpr_uint8 *end) {
   gpr_log(GPR_INFO, "MAX TABLE SIZE: %d", p->index);
-  abort(); /* not implemented */
-  return parse_begin(p, cur, end);
+  return grpc_chttp2_hptbl_set_current_table_size(&p->table, p->index) &&
+         parse_begin(p, cur, end);
 }
 
 /* parse a max table size change, max size < 15 */
 static int parse_max_tbl_size(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
                               const gpr_uint8 *end) {
-  p->index = (*cur) & 0xf;
+  p->index = (*cur) & 0x1f;
   return finish_max_tbl_size(p, cur + 1, end);
 }
 
@@ -918,7 +925,7 @@ static int parse_max_tbl_size_x(grpc_chttp2_hpack_parser *p,
   static const grpc_chttp2_hpack_parser_state and_then[] = {
       finish_max_tbl_size};
   p->next_state = and_then;
-  p->index = 0xf;
+  p->index = 0x1f;
   p->parsing.value = &p->index;
   return parse_value0(p, cur + 1, end);
 }
@@ -930,6 +937,13 @@ static int parse_error(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
   return 0;
 }
 
+static int parse_illegal_op(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
+                            const gpr_uint8 *end) {
+  GPR_ASSERT(cur != end);
+  gpr_log(GPR_DEBUG, "Illegal hpack op code %d", *cur);
+  return parse_error(p, cur, end);
+}
+
 /* parse the 1st byte of a varint into p->parsing.value
    no overflow is possible */
 static int parse_value0(grpc_chttp2_hpack_parser *p, const gpr_uint8 *cur,
diff --git a/src/core/transport/chttp2/hpack_table.c b/src/core/transport/chttp2/hpack_table.c
index c442c2c341..f2362b056c 100644
--- a/src/core/transport/chttp2/hpack_table.c
+++ b/src/core/transport/chttp2/hpack_table.c
@@ -36,7 +36,9 @@
 #include <assert.h>
 #include <string.h>
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
+
 #include "src/core/support/murmur_hash.h"
 
 static struct {
@@ -169,12 +171,22 @@ static struct {
     {"www-authenticate", ""},
 };
 
+static gpr_uint32 entries_for_bytes(gpr_uint32 bytes) {
+  return (bytes + GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD - 1) /
+         GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD;
+}
+
 void grpc_chttp2_hptbl_init(grpc_chttp2_hptbl *tbl, grpc_mdctx *mdctx) {
   size_t i;
 
   memset(tbl, 0, sizeof(*tbl));
   tbl->mdctx = mdctx;
-  tbl->max_bytes = GRPC_CHTTP2_INITIAL_HPACK_TABLE_SIZE;
+  tbl->current_table_bytes = tbl->max_bytes =
+      GRPC_CHTTP2_INITIAL_HPACK_TABLE_SIZE;
+  tbl->max_entries = tbl->cap_entries =
+      entries_for_bytes(tbl->current_table_bytes);
+  tbl->ents = gpr_malloc(sizeof(*tbl->ents) * tbl->cap_entries);
+  memset(tbl->ents, 0, sizeof(*tbl->ents) * tbl->cap_entries);
   for (i = 1; i <= GRPC_CHTTP2_LAST_STATIC_ENTRY; i++) {
     tbl->static_ents[i - 1] = grpc_mdelem_from_strings(
         mdctx, static_table[i].key, static_table[i].value);
@@ -187,9 +199,9 @@ void grpc_chttp2_hptbl_destroy(grpc_chttp2_hptbl *tbl) {
     GRPC_MDELEM_UNREF(tbl->static_ents[i]);
   }
   for (i = 0; i < tbl->num_ents; i++) {
-    GRPC_MDELEM_UNREF(
-        tbl->ents[(tbl->first_ent + i) % GRPC_CHTTP2_MAX_TABLE_COUNT]);
+    GRPC_MDELEM_UNREF(tbl->ents[(tbl->first_ent + i) % tbl->cap_entries]);
   }
+  gpr_free(tbl->ents);
 }
 
 grpc_mdelem *grpc_chttp2_hptbl_lookup(const grpc_chttp2_hptbl *tbl,
@@ -201,8 +213,8 @@ grpc_mdelem *grpc_chttp2_hptbl_lookup(const grpc_chttp2_hptbl *tbl,
   /* Otherwise, find the value in the list of valid entries */
   tbl_index -= (GRPC_CHTTP2_LAST_STATIC_ENTRY + 1);
   if (tbl_index < tbl->num_ents) {
-    gpr_uint32 offset = (tbl->num_ents - 1u - tbl_index + tbl->first_ent) %
-                        GRPC_CHTTP2_MAX_TABLE_COUNT;
+    gpr_uint32 offset =
+        (tbl->num_ents - 1u - tbl_index + tbl->first_ent) % tbl->cap_entries;
     return tbl->ents[offset];
   }
   /* Invalid entry: return error */
@@ -216,21 +228,81 @@ static void evict1(grpc_chttp2_hptbl *tbl) {
                       GPR_SLICE_LENGTH(first_ent->value->slice) +
                       GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD;
   GPR_ASSERT(elem_bytes <= tbl->mem_used);
-  tbl->mem_used = (gpr_uint16)(tbl->mem_used - elem_bytes);
-  tbl->first_ent =
-      (gpr_uint16)((tbl->first_ent + 1) % GRPC_CHTTP2_MAX_TABLE_COUNT);
+  tbl->mem_used -= (gpr_uint32)elem_bytes;
+  tbl->first_ent = ((tbl->first_ent + 1) % tbl->cap_entries);
   tbl->num_ents--;
   GRPC_MDELEM_UNREF(first_ent);
 }
 
-void grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
+static void rebuild_ents(grpc_chttp2_hptbl *tbl, gpr_uint32 new_cap) {
+  grpc_mdelem **ents = gpr_malloc(sizeof(*ents) * new_cap);
+  gpr_uint32 i;
+
+  for (i = 0; i < tbl->num_ents; i++) {
+    ents[i] = tbl->ents[(tbl->first_ent + i) % tbl->cap_entries];
+  }
+  gpr_free(tbl->ents);
+  tbl->ents = ents;
+  tbl->cap_entries = new_cap;
+  tbl->first_ent = 0;
+}
+
+void grpc_chttp2_hptbl_set_max_bytes(grpc_chttp2_hptbl *tbl,
+                                     gpr_uint32 max_bytes) {
+  if (tbl->max_bytes == max_bytes) {
+    return;
+  }
+  gpr_log(GPR_DEBUG, "Update hpack parser max size to %d", max_bytes);
+  while (tbl->mem_used > max_bytes) {
+    evict1(tbl);
+  }
+  tbl->max_bytes = max_bytes;
+}
+
+int grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl *tbl,
+                                             gpr_uint32 bytes) {
+  if (tbl->current_table_bytes == bytes) {
+    return 1;
+  }
+  if (bytes > tbl->max_bytes) {
+    gpr_log(GPR_ERROR,
+            "Attempt to make hpack table %d bytes when max is %d bytes", bytes,
+            tbl->max_bytes);
+    return 0;
+  }
+  gpr_log(GPR_DEBUG, "Update hpack parser table size to %d", bytes);
+  while (tbl->mem_used > bytes) {
+    evict1(tbl);
+  }
+  tbl->current_table_bytes = bytes;
+  tbl->max_entries = entries_for_bytes(bytes);
+  if (tbl->max_entries > tbl->cap_entries) {
+    rebuild_ents(tbl, GPR_MAX(tbl->max_entries, 2 * tbl->cap_entries));
+  } else if (tbl->max_entries < tbl->cap_entries / 3) {
+    gpr_uint32 new_cap = GPR_MAX(tbl->max_entries, 16u);
+    if (new_cap != tbl->cap_entries) {
+      rebuild_ents(tbl, new_cap);
+    }
+  }
+  return 1;
+}
+
+int grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
   /* determine how many bytes of buffer this entry represents */
   size_t elem_bytes = GPR_SLICE_LENGTH(md->key->slice) +
                       GPR_SLICE_LENGTH(md->value->slice) +
                       GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD;
 
+  if (tbl->current_table_bytes > tbl->max_bytes) {
+    gpr_log(GPR_ERROR,
+            "HPACK max table size reduced to %d but not reflected by hpack "
+            "stream (still at %d)",
+            tbl->max_bytes, tbl->current_table_bytes);
+    return 0;
+  }
+
   /* we can't add elements bigger than the max table size */
-  if (elem_bytes > tbl->max_bytes) {
+  if (elem_bytes > tbl->current_table_bytes) {
     /* HPACK draft 10 section 4.4 states:
      * If the size of the new entry is less than or equal to the maximum
      * size, that entry is added to the table.  It is not an error to
@@ -243,44 +315,43 @@ void grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
     while (tbl->num_ents) {
       evict1(tbl);
     }
-    return;
+    return 1;
   }
 
   /* evict entries to ensure no overflow */
-  while (elem_bytes > (size_t)tbl->max_bytes - tbl->mem_used) {
+  while (elem_bytes > (size_t)tbl->current_table_bytes - tbl->mem_used) {
     evict1(tbl);
   }
 
   /* copy the finalized entry in */
-  tbl->ents[tbl->last_ent] = md;
+  tbl->ents[(tbl->first_ent + tbl->num_ents) % tbl->cap_entries] =
+      GRPC_MDELEM_REF(md);
 
   /* update accounting values */
-  tbl->last_ent =
-      (gpr_uint16)((tbl->last_ent + 1) % GRPC_CHTTP2_MAX_TABLE_COUNT);
   tbl->num_ents++;
-  tbl->mem_used = (gpr_uint16)(tbl->mem_used + elem_bytes);
+  tbl->mem_used += (gpr_uint32)elem_bytes;
+  return 1;
 }
 
 grpc_chttp2_hptbl_find_result grpc_chttp2_hptbl_find(
     const grpc_chttp2_hptbl *tbl, grpc_mdelem *md) {
   grpc_chttp2_hptbl_find_result r = {0, 0};
-  gpr_uint16 i;
+  gpr_uint32 i;
 
   /* See if the string is in the static table */
   for (i = 0; i < GRPC_CHTTP2_LAST_STATIC_ENTRY; i++) {
     grpc_mdelem *ent = tbl->static_ents[i];
     if (md->key != ent->key) continue;
-    r.index = (gpr_uint16)(i + 1);
+    r.index = i + 1u;
     r.has_value = md->value == ent->value;
     if (r.has_value) return r;
   }
 
   /* Scan the dynamic table */
   for (i = 0; i < tbl->num_ents; i++) {
-    gpr_uint16 idx =
-        (gpr_uint16)(tbl->num_ents - i + GRPC_CHTTP2_LAST_STATIC_ENTRY);
-    grpc_mdelem *ent =
-        tbl->ents[(tbl->first_ent + i) % GRPC_CHTTP2_MAX_TABLE_COUNT];
+    gpr_uint32 idx =
+        (gpr_uint32)(tbl->num_ents - i + GRPC_CHTTP2_LAST_STATIC_ENTRY);
+    grpc_mdelem *ent = tbl->ents[(tbl->first_ent + i) % tbl->cap_entries];
     if (md->key != ent->key) continue;
     r.index = idx;
     r.has_value = md->value == ent->value;
diff --git a/src/core/transport/chttp2/hpack_table.h b/src/core/transport/chttp2/hpack_table.h
index 4f882e2e03..e03b8c19b3 100644
--- a/src/core/transport/chttp2/hpack_table.h
+++ b/src/core/transport/chttp2/hpack_table.h
@@ -49,47 +49,59 @@
 #define GRPC_CHTTP2_MAX_HPACK_TABLE_SIZE GRPC_CHTTP2_INITIAL_HPACK_TABLE_SIZE
 /* Per entry overhead bytes as per the spec */
 #define GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD 32
+#if 0
 /* Maximum number of entries we could possibly fit in the table, given defined
    overheads */
 #define GRPC_CHTTP2_MAX_TABLE_COUNT                                            \
   ((GRPC_CHTTP2_MAX_HPACK_TABLE_SIZE + GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD - 1) / \
    GRPC_CHTTP2_HPACK_ENTRY_OVERHEAD)
+#endif
 
 /* hpack decoder table */
 typedef struct {
   grpc_mdctx *mdctx;
   /* the first used entry in ents */
-  gpr_uint16 first_ent;
-  /* the last used entry in ents */
-  gpr_uint16 last_ent;
+  gpr_uint32 first_ent;
   /* how many entries are in the table */
-  gpr_uint16 num_ents;
+  gpr_uint32 num_ents;
   /* the amount of memory used by the table, according to the hpack algorithm */
-  gpr_uint16 mem_used;
+  gpr_uint32 mem_used;
   /* the max memory allowed to be used by the table, according to the hpack
      algorithm */
-  gpr_uint16 max_bytes;
+  gpr_uint32 max_bytes;
+  /* the currently agreed size of the table, according to the hpack algorithm */
+  gpr_uint32 current_table_bytes;
+  /* Maximum number of entries we could possibly fit in the table, given defined
+     overheads */
+  gpr_uint32 max_entries;
+  /* Number of entries allocated in ents */
+  gpr_uint32 cap_entries;
   /* a circular buffer of headers - this is stored in the opposite order to
      what hpack specifies, in order to simplify table management a little...
      meaning lookups need to SUBTRACT from the end position */
-  grpc_mdelem *ents[GRPC_CHTTP2_MAX_TABLE_COUNT];
+  grpc_mdelem **ents;
   grpc_mdelem *static_ents[GRPC_CHTTP2_LAST_STATIC_ENTRY];
 } grpc_chttp2_hptbl;
 
 /* initialize a hpack table */
 void grpc_chttp2_hptbl_init(grpc_chttp2_hptbl *tbl, grpc_mdctx *mdctx);
 void grpc_chttp2_hptbl_destroy(grpc_chttp2_hptbl *tbl);
+void grpc_chttp2_hptbl_set_max_bytes(grpc_chttp2_hptbl *tbl,
+                                     gpr_uint32 max_bytes);
+int grpc_chttp2_hptbl_set_current_table_size(grpc_chttp2_hptbl *tbl,
+                                             gpr_uint32 bytes);
 
 /* lookup a table entry based on its hpack index */
 grpc_mdelem *grpc_chttp2_hptbl_lookup(const grpc_chttp2_hptbl *tbl,
                                       gpr_uint32 index);
 /* add a table entry to the index */
-void grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl, grpc_mdelem *md);
+int grpc_chttp2_hptbl_add(grpc_chttp2_hptbl *tbl,
+                          grpc_mdelem *md) GRPC_MUST_USE_RESULT;
 /* Find a key/value pair in the table... returns the index in the table of the
    most similar entry, or 0 if the value was not found */
 typedef struct {
-  gpr_uint16 index;
-  gpr_uint8 has_value;
+  gpr_uint32 index;
+  int has_value;
 } grpc_chttp2_hptbl_find_result;
 grpc_chttp2_hptbl_find_result grpc_chttp2_hptbl_find(
     const grpc_chttp2_hptbl *tbl, grpc_mdelem *md);
diff --git a/src/core/transport/chttp2/internal.h b/src/core/transport/chttp2/internal.h
index 2d0cb4abdb..216439549c 100644
--- a/src/core/transport/chttp2/internal.h
+++ b/src/core/transport/chttp2/internal.h
@@ -227,6 +227,9 @@ struct grpc_chttp2_transport_parsing {
   /** was a goaway frame received? */
   gpr_uint8 goaway_received;
 
+  /** the last sent max_table_size setting */
+  gpr_uint32 last_sent_max_table_size;
+
   /** initial window change */
   gpr_int64 initial_window_update;
 
@@ -483,7 +486,8 @@ struct grpc_chttp2_stream {
 /** Someone is unlocking the transport mutex: check to see if writes
     are required, and schedule them if so */
 int grpc_chttp2_unlocking_check_writes(grpc_chttp2_transport_global *global,
-                                       grpc_chttp2_transport_writing *writing);
+                                       grpc_chttp2_transport_writing *writing,
+                                       int is_parsing);
 void grpc_chttp2_perform_writes(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_writing *transport_writing,
     grpc_endpoint *endpoint);
diff --git a/src/core/transport/chttp2/parsing.c b/src/core/transport/chttp2/parsing.c
index 8cef8fbb77..1e06532c03 100644
--- a/src/core/transport/chttp2/parsing.c
+++ b/src/core/transport/chttp2/parsing.c
@@ -78,6 +78,9 @@ void grpc_chttp2_prepare_to_read(
   GPR_TIMER_BEGIN("grpc_chttp2_prepare_to_read", 0);
 
   transport_parsing->next_stream_id = transport_global->next_stream_id;
+  transport_parsing->last_sent_max_table_size =
+      transport_global->settings[GRPC_SENT_SETTINGS]
+                                [GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE];
 
   /* update the parsing view of incoming window */
   while (grpc_chttp2_list_pop_unannounced_incoming_window_available(
@@ -127,6 +130,7 @@ void grpc_chttp2_publish_reads(
            transport_global->settings[GRPC_SENT_SETTINGS],
            GRPC_CHTTP2_NUM_SETTINGS * sizeof(gpr_uint32));
     transport_parsing->settings_ack_received = 0;
+    transport_global->sent_local_settings = 0;
   }
 
   /* move goaway to the global state if we received one (it will be
@@ -819,6 +823,9 @@ static int init_settings_frame_parser(
   }
   if (transport_parsing->incoming_frame_flags & GRPC_CHTTP2_FLAG_ACK) {
     transport_parsing->settings_ack_received = 1;
+    grpc_chttp2_hptbl_set_max_bytes(
+        &transport_parsing->hpack_parser.table,
+        transport_parsing->last_sent_max_table_size);
   }
   transport_parsing->parser = grpc_chttp2_settings_parser_parse;
   transport_parsing->parser_data = &transport_parsing->simple.settings;
diff --git a/src/core/transport/chttp2/writing.c b/src/core/transport/chttp2/writing.c
index 7fe5649e5e..805d05222d 100644
--- a/src/core/transport/chttp2/writing.c
+++ b/src/core/transport/chttp2/writing.c
@@ -45,7 +45,7 @@ static void finalize_outbuf(grpc_exec_ctx *exec_ctx,
 
 int grpc_chttp2_unlocking_check_writes(
     grpc_chttp2_transport_global *transport_global,
-    grpc_chttp2_transport_writing *transport_writing) {
+    grpc_chttp2_transport_writing *transport_writing, int is_parsing) {
   grpc_chttp2_stream_global *stream_global;
   grpc_chttp2_stream_writing *stream_writing;
 
@@ -55,8 +55,13 @@ int grpc_chttp2_unlocking_check_writes(
   gpr_slice_buffer_swap(&transport_global->qbuf, &transport_writing->outbuf);
   GPR_ASSERT(transport_global->qbuf.count == 0);
 
+  grpc_chttp2_hpack_compressor_set_max_table_size(
+      &transport_writing->hpack_compressor,
+      transport_global->settings[GRPC_PEER_SETTINGS]
+                                [GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE]);
+
   if (transport_global->dirtied_local_settings &&
-      !transport_global->sent_local_settings) {
+      !transport_global->sent_local_settings && !is_parsing) {
     gpr_slice_buffer_add(
         &transport_writing->outbuf,
         grpc_chttp2_settings_create(
diff --git a/src/core/transport/chttp2_transport.c b/src/core/transport/chttp2_transport.c
index f62294c7c5..fdd835def9 100644
--- a/src/core/transport/chttp2_transport.c
+++ b/src/core/transport/chttp2_transport.c
@@ -338,6 +338,31 @@ static void init_transport(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
           t->global.next_stream_id =
               (gpr_uint32)channel_args->args[i].value.integer;
         }
+      } else if (0 == strcmp(channel_args->args[i].key,
+                             GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER)) {
+        if (channel_args->args[i].type != GRPC_ARG_INTEGER) {
+          gpr_log(GPR_ERROR, "%s: must be an integer",
+                  GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER);
+        } else if (channel_args->args[i].value.integer < 0) {
+          gpr_log(GPR_DEBUG, "%s: must be non-negative",
+                  GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_DECODER);
+        } else {
+          push_setting(t, GRPC_CHTTP2_SETTINGS_HEADER_TABLE_SIZE,
+                       (gpr_uint32)channel_args->args[i].value.integer);
+        }
+      } else if (0 == strcmp(channel_args->args[i].key,
+                             GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_ENCODER)) {
+        if (channel_args->args[i].type != GRPC_ARG_INTEGER) {
+          gpr_log(GPR_ERROR, "%s: must be an integer",
+                  GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_ENCODER);
+        } else if (channel_args->args[i].value.integer < 0) {
+          gpr_log(GPR_DEBUG, "%s: must be non-negative",
+                  GRPC_ARG_HTTP2_HPACK_TABLE_SIZE_ENCODER);
+        } else {
+          grpc_chttp2_hpack_compressor_set_max_usable_size(
+              &t->writing.hpack_compressor,
+              (gpr_uint32)channel_args->args[i].value.integer);
+        }
       }
     }
   }
@@ -563,7 +588,8 @@ static void lock(grpc_chttp2_transport *t) { gpr_mu_lock(&t->mu); }
 static void unlock(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t) {
   GPR_TIMER_BEGIN("unlock", 0);
   if (!t->writing_active && !t->closed &&
-      grpc_chttp2_unlocking_check_writes(&t->global, &t->writing)) {
+      grpc_chttp2_unlocking_check_writes(&t->global, &t->writing,
+                                         t->parsing_active)) {
     t->writing_active = 1;
     REF_TRANSPORT(t, "writing");
     grpc_exec_ctx_enqueue(exec_ctx, &t->writing_action, 1);
@@ -735,6 +761,8 @@ static int contains_non_ok_status(
   return 0;
 }
 
+static void do_nothing(grpc_exec_ctx *exec_ctx, void *arg, int success) {}
+
 static void perform_stream_op_locked(
     grpc_exec_ctx *exec_ctx, grpc_chttp2_transport_global *transport_global,
     grpc_chttp2_stream_global *stream_global, grpc_transport_stream_op *op) {
@@ -743,6 +771,9 @@ static void perform_stream_op_locked(
   GPR_TIMER_BEGIN("perform_stream_op_locked", 0);
 
   on_complete = op->on_complete;
+  if (on_complete == NULL) {
+    on_complete = grpc_closure_create(do_nothing, NULL);
+  }
   /* use final_data as a barrier until enqueue time; the inital counter is
      dropped at the end of this function */
   on_complete->final_data = 2;
@@ -806,7 +837,7 @@ static void perform_stream_op_locked(
     }
     if (stream_global->write_closed) {
       grpc_chttp2_complete_closure_step(
-          exec_ctx, &stream_global->send_trailing_metadata_finished, 
+          exec_ctx, &stream_global->send_trailing_metadata_finished,
           grpc_metadata_batch_is_empty(op->send_trailing_metadata));
     } else if (stream_global->id != 0) {
       /* TODO(ctiller): check if there's flow control for any outstanding
@@ -1033,7 +1064,8 @@ void grpc_chttp2_fake_status(grpc_exec_ctx *exec_ctx,
      to the upper layers - drop what we've got, and then publish
      what we want - which is safe because we haven't told anyone
      about the metadata yet */
-  if (!stream_global->published_trailing_metadata || stream_global->recv_trailing_metadata_finished != NULL) {
+  if (!stream_global->published_trailing_metadata ||
+      stream_global->recv_trailing_metadata_finished != NULL) {
     grpc_mdctx *mdctx =
         TRANSPORT_FROM_GLOBAL(transport_global)->metadata_context;
     char status_string[GPR_LTOA_MIN_BUFSIZE];
diff --git a/src/core/tsi/test_creds/server1.pem b/src/core/tsi/test_creds/server1.pem
index 8e582e571f..f3d43fcc5b 100644
--- a/src/core/tsi/test_creds/server1.pem
+++ b/src/core/tsi/test_creds/server1.pem
@@ -1,16 +1,16 @@
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