Merge github.com:grpc/grpc into write_buffering

52 files changed, 589 insertions, 246 deletions

diff --git a/src/core/ext/README.md b/src/core/ext/README.md
new file mode 100644
index 0000000000..0812b20823
--- /dev/null
+++ b/src/core/ext/README.md
@@ -0,0 +1,5 @@
+Optional plugins for gRPC Core: Modules in this directory extend gRPC Core in
+useful ways. All optional code belongs here.
+
+NOTE: The movement of code between lib and ext is an ongoing effort, so this
+directory currently contains too much of the core library.
diff --git a/src/core/ext/census/tracing.c b/src/core/ext/census/tracing.c
index 8f0e12296d..3b5d6dab2b 100644
--- a/src/core/ext/census/tracing.c
+++ b/src/core/ext/census/tracing.c
@@ -31,19 +31,15 @@
  *
  */
 
-//#include "src/core/ext/census/tracing.h"
-
 #include <grpc/census.h>
 
 /* TODO(aveitch): These are all placeholder implementations. */
 
-// int census_trace_mask(const census_context *context) {
-//   return CENSUS_TRACE_MASK_NONE;
-// }
-
-// void census_set_trace_mask(int trace_mask) {}
+int census_trace_mask(const census_context *context) {
+  return CENSUS_TRACE_MASK_NONE;
+}
 
-// void census_trace_print(census_context *context, uint32_t type,
-//                         const char *buffer, size_t n) {}
+void census_set_trace_mask(int trace_mask) {}
 
-// void SetTracerParams(const Params& params);
+void census_trace_print(census_context *context, uint32_t type,
+                        const char *buffer, size_t n) {}
diff --git a/src/core/ext/client_channel/channel_connectivity.c b/src/core/ext/client_channel/channel_connectivity.c
index b10f444b63..dd70bc2c6c 100644
--- a/src/core/ext/client_channel/channel_connectivity.c
+++ b/src/core/ext/client_channel/channel_connectivity.c
@@ -76,6 +76,7 @@ typedef struct {
   gpr_mu mu;
   callback_phase phase;
   grpc_closure on_complete;
+  grpc_closure on_timeout;
   grpc_timer alarm;
   grpc_connectivity_state state;
   grpc_completion_queue *cq;
@@ -200,6 +201,8 @@ void grpc_channel_watch_connectivity_state(
   gpr_mu_init(&w->mu);
   grpc_closure_init(&w->on_complete, watch_complete, w,
                     grpc_schedule_on_exec_ctx);
+  grpc_closure_init(&w->on_timeout, timeout_complete, w,
+                    grpc_schedule_on_exec_ctx);
   w->phase = WAITING;
   w->state = last_observed_state;
   w->cq = cq;
@@ -208,7 +211,7 @@ void grpc_channel_watch_connectivity_state(
 
   grpc_timer_init(&exec_ctx, &w->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  timeout_complete, w, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &w->on_timeout, gpr_now(GPR_CLOCK_MONOTONIC));
 
   if (client_channel_elem->filter == &grpc_client_channel_filter) {
     GRPC_CHANNEL_INTERNAL_REF(channel, "watch_channel_connectivity");
diff --git a/src/core/ext/client_channel/client_channel_plugin.c b/src/core/ext/client_channel/client_channel_plugin.c
index 988b7a1d5c..d50bba60f6 100644
--- a/src/core/ext/client_channel/client_channel_plugin.c
+++ b/src/core/ext/client_channel/client_channel_plugin.c
@@ -38,6 +38,7 @@
 #include <grpc/support/alloc.h>
 
 #include "src/core/ext/client_channel/client_channel.h"
+#include "src/core/ext/client_channel/http_connect_handshaker.h"
 #include "src/core/ext/client_channel/lb_policy_registry.h"
 #include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/client_channel/subchannel_index.h"
@@ -84,6 +85,7 @@ void grpc_client_channel_init(void) {
                                    set_default_host_if_unset, NULL);
   grpc_channel_init_register_stage(GRPC_CLIENT_CHANNEL, INT_MAX, append_filter,
                                    (void *)&grpc_client_channel_filter);
+  grpc_http_connect_register_handshaker_factory();
 }
 
 void grpc_client_channel_shutdown(void) {
diff --git a/src/core/ext/client_channel/http_connect_handshaker.c b/src/core/ext/client_channel/http_connect_handshaker.c
index 27b117af84..fba32561ac 100644
--- a/src/core/ext/client_channel/http_connect_handshaker.c
+++ b/src/core/ext/client_channel/http_connect_handshaker.c
@@ -44,6 +44,7 @@
 #include "src/core/ext/client_channel/resolver_registry.h"
 #include "src/core/ext/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/http/format_request.h"
 #include "src/core/lib/http/parser.h"
 #include "src/core/lib/slice/slice_internal.h"
@@ -54,6 +55,8 @@ typedef struct http_connect_handshaker {
   grpc_handshaker base;
 
   char* proxy_server;
+  grpc_http_header* headers;
+  size_t num_headers;
 
   gpr_refcount refcount;
   gpr_mu mu;
@@ -89,6 +92,11 @@ static void http_connect_handshaker_unref(grpc_exec_ctx* exec_ctx,
       gpr_free(handshaker->read_buffer_to_destroy);
     }
     gpr_free(handshaker->proxy_server);
+    for (size_t i = 0; i < handshaker->num_headers; ++i) {
+      gpr_free(handshaker->headers[i].key);
+      gpr_free(handshaker->headers[i].value);
+    }
+    gpr_free(handshaker->headers);
     grpc_slice_buffer_destroy_internal(exec_ctx, &handshaker->write_buffer);
     grpc_http_parser_destroy(&handshaker->http_parser);
     grpc_http_response_destroy(&handshaker->http_response);
@@ -289,6 +297,8 @@ static void http_connect_handshaker_do_handshake(
   request.host = server_name;
   request.http.method = "CONNECT";
   request.http.path = server_name;
+  request.http.hdrs = handshaker->headers;
+  request.http.hdr_count = handshaker->num_headers;
   request.handshaker = &grpc_httpcli_plaintext;
   grpc_slice request_slice = grpc_httpcli_format_connect_request(&request);
   grpc_slice_buffer_add(&handshaker->write_buffer, request_slice);
@@ -306,7 +316,9 @@ static const grpc_handshaker_vtable http_connect_handshaker_vtable = {
     http_connect_handshaker_destroy, http_connect_handshaker_shutdown,
     http_connect_handshaker_do_handshake};
 
-grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server) {
+grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server,
+                                                     grpc_http_header* headers,
+                                                     size_t num_headers) {
   GPR_ASSERT(proxy_server != NULL);
   http_connect_handshaker* handshaker = gpr_malloc(sizeof(*handshaker));
   memset(handshaker, 0, sizeof(*handshaker));
@@ -314,6 +326,14 @@ grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server) {
   gpr_mu_init(&handshaker->mu);
   gpr_ref_init(&handshaker->refcount, 1);
   handshaker->proxy_server = gpr_strdup(proxy_server);
+  if (num_headers > 0) {
+    handshaker->headers = gpr_malloc(sizeof(grpc_http_header) * num_headers);
+    for (size_t i = 0; i < num_headers; ++i) {
+      handshaker->headers[i].key = gpr_strdup(headers[i].key);
+      handshaker->headers[i].value = gpr_strdup(headers[i].value);
+    }
+    handshaker->num_headers = num_headers;
+  }
   grpc_slice_buffer_init(&handshaker->write_buffer);
   grpc_closure_init(&handshaker->request_done_closure, on_write_done,
                     handshaker, grpc_schedule_on_exec_ctx);
@@ -347,3 +367,33 @@ done:
   grpc_uri_destroy(uri);
   return proxy_name;
 }
+
+//
+// handshaker factory
+//
+
+static void handshaker_factory_add_handshakers(
+    grpc_exec_ctx* exec_ctx, grpc_handshaker_factory* factory,
+    const grpc_channel_args* args, grpc_handshake_manager* handshake_mgr) {
+  char* proxy_name = grpc_get_http_proxy_server();
+  if (proxy_name != NULL) {
+    grpc_handshake_manager_add(
+        handshake_mgr,
+        grpc_http_connect_handshaker_create(proxy_name, NULL, 0));
+    gpr_free(proxy_name);
+  }
+}
+
+static void handshaker_factory_destroy(grpc_exec_ctx* exec_ctx,
+                                       grpc_handshaker_factory* factory) {}
+
+static const grpc_handshaker_factory_vtable handshaker_factory_vtable = {
+    handshaker_factory_add_handshakers, handshaker_factory_destroy};
+
+static grpc_handshaker_factory handshaker_factory = {
+    &handshaker_factory_vtable};
+
+void grpc_http_connect_register_handshaker_factory() {
+  grpc_handshaker_factory_register(true /* at_start */, HANDSHAKER_CLIENT,
+                                   &handshaker_factory);
+}
diff --git a/src/core/ext/client_channel/http_connect_handshaker.h b/src/core/ext/client_channel/http_connect_handshaker.h
index ea293852e6..c2e68de716 100644
--- a/src/core/ext/client_channel/http_connect_handshaker.h
+++ b/src/core/ext/client_channel/http_connect_handshaker.h
@@ -35,12 +35,18 @@
 #define GRPC_CORE_EXT_CLIENT_CHANNEL_HTTP_CONNECT_HANDSHAKER_H
 
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/http/parser.h"
 
-/// Does NOT take ownership of \a proxy_server.
-grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server);
+/// Creates a new HTTP CONNECT handshaker.
+grpc_handshaker* grpc_http_connect_handshaker_create(const char* proxy_server,
+                                                     grpc_http_header* headers,
+                                                     size_t num_headers);
 
 /// Returns the name of the proxy to use, or NULL if no proxy is configured.
 /// Caller takes ownership of result.
 char* grpc_get_http_proxy_server();
 
+/// Registers handshaker factory.
+void grpc_http_connect_register_handshaker_factory();
+
 #endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_HTTP_CONNECT_HANDSHAKER_H */
diff --git a/src/core/ext/client_channel/subchannel.c b/src/core/ext/client_channel/subchannel.c
index fad5c69c83..1bac82b451 100644
--- a/src/core/ext/client_channel/subchannel.c
+++ b/src/core/ext/client_channel/subchannel.c
@@ -109,6 +109,9 @@ struct grpc_subchannel {
   /** callback for connection finishing */
   grpc_closure connected;
 
+  /** callback for our alarm */
+  grpc_closure on_alarm;
+
   /** pollset_set tracking who's interested in a connection
       being setup */
   grpc_pollset_set *pollset_set;
@@ -483,7 +486,8 @@ static void maybe_start_connecting_locked(grpc_exec_ctx *exec_ctx,
       gpr_log(GPR_INFO, "Retry in %" PRId64 ".%09d seconds",
               time_til_next.tv_sec, time_til_next.tv_nsec);
     }
-    grpc_timer_init(exec_ctx, &c->alarm, c->next_attempt, on_alarm, c, now);
+    grpc_closure_init(&c->on_alarm, on_alarm, c, grpc_schedule_on_exec_ctx);
+    grpc_timer_init(exec_ctx, &c->alarm, c->next_attempt, &c->on_alarm, now);
   }
 }
 
diff --git a/src/core/ext/lb_policy/grpclb/grpclb.c b/src/core/ext/lb_policy/grpclb/grpclb.c
index 2d48a3a9e7..97f98df03a 100644
--- a/src/core/ext/lb_policy/grpclb/grpclb.c
+++ b/src/core/ext/lb_policy/grpclb/grpclb.c
@@ -327,6 +327,9 @@ typedef struct glb_lb_policy {
   /* A response from the LB server has been received. Process it */
   grpc_closure lb_on_response_received;
 
+  /* LB call retry timer callback. */
+  grpc_closure lb_on_call_retry;
+
   grpc_call *lb_call; /* streaming call to the LB server, */
 
   grpc_metadata_array lb_initial_metadata_recv; /* initial MD from LB server */
@@ -1364,8 +1367,10 @@ static void lb_on_server_status_received(grpc_exec_ctx *exec_ctx, void *arg,
       }
     }
     GRPC_LB_POLICY_WEAK_REF(&glb_policy->base, "grpclb_retry_timer");
+    grpc_closure_init(&glb_policy->lb_on_call_retry, lb_call_on_retry_timer,
+                      glb_policy, grpc_schedule_on_exec_ctx);
     grpc_timer_init(exec_ctx, &glb_policy->lb_call_retry_timer, next_try,
-                    lb_call_on_retry_timer, glb_policy, now);
+                    &glb_policy->lb_on_call_retry, now);
   }
   gpr_mu_unlock(&glb_policy->mu);
   GRPC_LB_POLICY_WEAK_UNREF(exec_ctx, &glb_policy->base,
diff --git a/src/core/ext/resolver/README.md b/src/core/ext/resolver/README.md
new file mode 100644
index 0000000000..b0e234e96a
--- /dev/null
+++ b/src/core/ext/resolver/README.md
@@ -0,0 +1,4 @@
+# Resolver
+
+Implementations of various name resolution schemes.
+See the [naming spec](/doc/naming.md).
diff --git a/src/core/ext/resolver/dns/native/dns_resolver.c b/src/core/ext/resolver/dns/native/dns_resolver.c
index 124b16bbc3..655d9dc586 100644
--- a/src/core/ext/resolver/dns/native/dns_resolver.c
+++ b/src/core/ext/resolver/dns/native/dns_resolver.c
@@ -81,6 +81,7 @@ typedef struct {
   /** retry timer */
   bool have_retry_timer;
   grpc_timer retry_timer;
+  grpc_closure on_retry;
   /** retry backoff state */
   gpr_backoff backoff_state;
 
@@ -188,7 +189,7 @@ static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
     gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
     gpr_timespec timeout = gpr_time_sub(next_try, now);
     const char *msg = grpc_error_string(error);
-    gpr_log(GPR_DEBUG, "dns resolution failed: %s", msg);
+    gpr_log(GPR_INFO, "dns resolution failed (will retry): %s", msg);
     grpc_error_free_string(msg);
     GPR_ASSERT(!r->have_retry_timer);
     r->have_retry_timer = true;
@@ -199,8 +200,9 @@ static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
     } else {
       gpr_log(GPR_DEBUG, "retrying immediately");
     }
-    grpc_timer_init(exec_ctx, &r->retry_timer, next_try, dns_on_retry_timer, r,
-                    now);
+    grpc_closure_init(&r->on_retry, dns_on_retry_timer, r,
+                      grpc_schedule_on_exec_ctx);
+    grpc_timer_init(exec_ctx, &r->retry_timer, next_try, &r->on_retry, now);
   }
   if (r->resolved_result != NULL) {
     grpc_channel_args_destroy(exec_ctx, r->resolved_result);
diff --git a/src/core/ext/transport/README.md b/src/core/ext/transport/README.md
new file mode 100644
index 0000000000..2290568784
--- /dev/null
+++ b/src/core/ext/transport/README.md
@@ -0,0 +1 @@
+Transports for gRPC
diff --git a/src/core/ext/transport/chttp2/README.md b/src/core/ext/transport/chttp2/README.md
new file mode 100644
index 0000000000..8880a47460
--- /dev/null
+++ b/src/core/ext/transport/chttp2/README.md
@@ -0,0 +1 @@
+CHTTP2 - gRPC's implementation of a HTTP2 based transport
diff --git a/src/core/ext/transport/chttp2/client/chttp2_connector.c b/src/core/ext/transport/chttp2/client/chttp2_connector.c
index 2385f91dbd..2c5dfaea60 100644
--- a/src/core/ext/transport/chttp2/client/chttp2_connector.c
+++ b/src/core/ext/transport/chttp2/client/chttp2_connector.c
@@ -46,6 +46,7 @@
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/iomgr/tcp_client.h"
 #include "src/core/lib/slice/slice_internal.h"
 
@@ -58,9 +59,6 @@ typedef struct {
   bool shutdown;
   bool connecting;
 
-  grpc_chttp2_add_handshakers_func add_handshakers;
-  void *add_handshakers_user_data;
-
   grpc_closure *notify;
   grpc_connect_in_args args;
   grpc_connect_out_args *result;
@@ -151,16 +149,8 @@ static void on_handshake_done(grpc_exec_ctx *exec_ctx, void *arg,
 static void start_handshake_locked(grpc_exec_ctx *exec_ctx,
                                    chttp2_connector *c) {
   c->handshake_mgr = grpc_handshake_manager_create();
-  char *proxy_name = grpc_get_http_proxy_server();
-  if (proxy_name != NULL) {
-    grpc_handshake_manager_add(c->handshake_mgr,
-                               grpc_http_connect_handshaker_create(proxy_name));
-    gpr_free(proxy_name);
-  }
-  if (c->add_handshakers != NULL) {
-    c->add_handshakers(exec_ctx, c->add_handshakers_user_data,
+  grpc_handshakers_add(exec_ctx, HANDSHAKER_CLIENT, c->args.channel_args,
                        c->handshake_mgr);
-  }
   grpc_handshake_manager_do_handshake(
       exec_ctx, c->handshake_mgr, c->endpoint, c->args.channel_args,
       c->args.deadline, NULL /* acceptor */, on_handshake_done, c);
@@ -250,15 +240,11 @@ static const grpc_connector_vtable chttp2_connector_vtable = {
     chttp2_connector_ref, chttp2_connector_unref, chttp2_connector_shutdown,
     chttp2_connector_connect};
 
-grpc_connector *grpc_chttp2_connector_create(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_add_handshakers_func add_handshakers,
-    void *add_handshakers_user_data) {
+grpc_connector *grpc_chttp2_connector_create() {
   chttp2_connector *c = gpr_malloc(sizeof(*c));
   memset(c, 0, sizeof(*c));
   c->base.vtable = &chttp2_connector_vtable;
   gpr_mu_init(&c->mu);
   gpr_ref_init(&c->refs, 1);
-  c->add_handshakers = add_handshakers;
-  c->add_handshakers_user_data = add_handshakers_user_data;
   return &c->base;
 }
diff --git a/src/core/ext/transport/chttp2/client/chttp2_connector.h b/src/core/ext/transport/chttp2/client/chttp2_connector.h
index 58eba22417..f5d1025432 100644
--- a/src/core/ext/transport/chttp2/client/chttp2_connector.h
+++ b/src/core/ext/transport/chttp2/client/chttp2_connector.h
@@ -35,17 +35,7 @@
 #define GRPC_CORE_EXT_TRANSPORT_CHTTP2_CLIENT_CHTTP2_CONNECTOR_H
 
 #include "src/core/ext/client_channel/connector.h"
-#include "src/core/lib/channel/handshaker.h"
-#include "src/core/lib/iomgr/exec_ctx.h"
 
-typedef void (*grpc_chttp2_add_handshakers_func)(
-    grpc_exec_ctx* exec_ctx, void* user_data,
-    grpc_handshake_manager* handshake_mgr);
-
-/// If \a add_handshakers is non-NULL, it will be called with
-/// \a add_handshakers_user_data to add handshakers.
-grpc_connector* grpc_chttp2_connector_create(
-    grpc_exec_ctx* exec_ctx, grpc_chttp2_add_handshakers_func add_handshakers,
-    void* add_handshakers_user_data);
+grpc_connector* grpc_chttp2_connector_create();
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_CLIENT_CHTTP2_CONNECTOR_H */
diff --git a/src/core/ext/transport/chttp2/client/insecure/channel_create.c b/src/core/ext/transport/chttp2/client/insecure/channel_create.c
index 1d3592ef06..c9f4021216 100644
--- a/src/core/ext/transport/chttp2/client/insecure/channel_create.c
+++ b/src/core/ext/transport/chttp2/client/insecure/channel_create.c
@@ -53,8 +53,7 @@ static void client_channel_factory_unref(
 static grpc_subchannel *client_channel_factory_create_subchannel(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory,
     const grpc_subchannel_args *args) {
-  grpc_connector *connector = grpc_chttp2_connector_create(
-      exec_ctx, NULL /* add_handshakers */, NULL /* user_data */);
+  grpc_connector *connector = grpc_chttp2_connector_create();
   grpc_subchannel *s = grpc_subchannel_create(exec_ctx, connector, args);
   grpc_connector_unref(exec_ctx, connector);
   return s;
@@ -96,17 +95,16 @@ grpc_channel *grpc_insecure_channel_create(const char *target,
       "grpc_insecure_channel_create(target=%p, args=%p, reserved=%p)", 3,
       (target, args, reserved));
   GPR_ASSERT(reserved == NULL);
-  grpc_client_channel_factory *factory =
-      (grpc_client_channel_factory *)&client_channel_factory;
   // Add channel arg containing the client channel factory.
-  grpc_arg arg = grpc_client_channel_factory_create_channel_arg(factory);
+  grpc_arg arg =
+      grpc_client_channel_factory_create_channel_arg(&client_channel_factory);
   grpc_channel_args *new_args = grpc_channel_args_copy_and_add(args, &arg, 1);
   // Create channel.
   grpc_channel *channel = client_channel_factory_create_channel(
-      &exec_ctx, factory, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
+      &exec_ctx, &client_channel_factory, target,
+      GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
   // Clean up.
   grpc_channel_args_destroy(&exec_ctx, new_args);
-  grpc_client_channel_factory_unref(&exec_ctx, factory);
   grpc_exec_ctx_finish(&exec_ctx);
   return channel != NULL ? channel : grpc_lame_client_channel_create(
                                          target, GRPC_STATUS_INTERNAL,
diff --git a/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c b/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c
index 54663ef6a4..f979d9bad5 100644
--- a/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c
+++ b/src/core/ext/transport/chttp2/client/secure/secure_channel_create.c
@@ -46,40 +46,16 @@
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/channel.h"
 
-typedef struct {
-  grpc_client_channel_factory base;
-  gpr_refcount refs;
-  grpc_channel_security_connector *security_connector;
-} client_channel_factory;
-
 static void client_channel_factory_ref(
-    grpc_client_channel_factory *cc_factory) {
-  client_channel_factory *f = (client_channel_factory *)cc_factory;
-  gpr_ref(&f->refs);
-}
+    grpc_client_channel_factory *cc_factory) {}
 
 static void client_channel_factory_unref(
-    grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory) {
-  client_channel_factory *f = (client_channel_factory *)cc_factory;
-  if (gpr_unref(&f->refs)) {
-    GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, &f->security_connector->base,
-                                  "client_channel_factory");
-    gpr_free(f);
-  }
-}
-
-static void add_handshakers(grpc_exec_ctx *exec_ctx, void *security_connector,
-                            grpc_handshake_manager *handshake_mgr) {
-  grpc_channel_security_connector_add_handshakers(exec_ctx, security_connector,
-                                                  handshake_mgr);
-}
+    grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory) {}
 
 static grpc_subchannel *client_channel_factory_create_subchannel(
     grpc_exec_ctx *exec_ctx, grpc_client_channel_factory *cc_factory,
     const grpc_subchannel_args *args) {
-  client_channel_factory *f = (client_channel_factory *)cc_factory;
-  grpc_connector *connector = grpc_chttp2_connector_create(
-      exec_ctx, add_handshakers, f->security_connector);
+  grpc_connector *connector = grpc_chttp2_connector_create();
   grpc_subchannel *s = grpc_subchannel_create(exec_ctx, connector, args);
   grpc_connector_unref(exec_ctx, connector);
   return s;
@@ -106,6 +82,9 @@ static const grpc_client_channel_factory_vtable client_channel_factory_vtable =
      client_channel_factory_create_subchannel,
      client_channel_factory_create_channel};
 
+static grpc_client_channel_factory client_channel_factory = {
+    &client_channel_factory_vtable};
+
 /* Create a secure client channel:
    Asynchronously: - resolve target
                    - connect to it (trying alternatives as presented)
@@ -138,33 +117,26 @@ grpc_channel *grpc_secure_channel_create(grpc_channel_credentials *creds,
     return grpc_lame_client_channel_create(
         target, GRPC_STATUS_INTERNAL, "Failed to create security connector.");
   }
-  // Create client channel factory.
-  client_channel_factory *f = gpr_malloc(sizeof(*f));
-  memset(f, 0, sizeof(*f));
-  f->base.vtable = &client_channel_factory_vtable;
-  gpr_ref_init(&f->refs, 1);
-  GRPC_SECURITY_CONNECTOR_REF(&security_connector->base,
-                              "grpc_secure_channel_create");
-  f->security_connector = security_connector;
   // Add channel args containing the client channel factory and security
   // connector.
-  grpc_arg new_args[2];
-  new_args[0] = grpc_client_channel_factory_create_channel_arg(&f->base);
-  new_args[1] = grpc_security_connector_to_arg(&security_connector->base);
-  grpc_channel_args *args_copy = grpc_channel_args_copy_and_add(
+  grpc_arg args_to_add[2];
+  args_to_add[0] =
+      grpc_client_channel_factory_create_channel_arg(&client_channel_factory);
+  args_to_add[1] = grpc_security_connector_to_arg(&security_connector->base);
+  grpc_channel_args *new_args = grpc_channel_args_copy_and_add(
       new_args_from_connector != NULL ? new_args_from_connector : args,
-      new_args, GPR_ARRAY_SIZE(new_args));
+      args_to_add, GPR_ARRAY_SIZE(args_to_add));
   if (new_args_from_connector != NULL) {
     grpc_channel_args_destroy(&exec_ctx, new_args_from_connector);
   }
   // Create channel.
   grpc_channel *channel = client_channel_factory_create_channel(
-      &exec_ctx, &f->base, target, GRPC_CLIENT_CHANNEL_TYPE_REGULAR, args_copy);
+      &exec_ctx, &client_channel_factory, target,
+      GRPC_CLIENT_CHANNEL_TYPE_REGULAR, new_args);
   // Clean up.
-  GRPC_SECURITY_CONNECTOR_UNREF(&exec_ctx, &f->security_connector->base,
+  GRPC_SECURITY_CONNECTOR_UNREF(&exec_ctx, &security_connector->base,
                                 "secure_client_channel_factory_create_channel");
-  grpc_channel_args_destroy(&exec_ctx, args_copy);
-  grpc_client_channel_factory_unref(&exec_ctx, &f->base);
+  grpc_channel_args_destroy(&exec_ctx, new_args);
   grpc_exec_ctx_finish(&exec_ctx);
   return channel; /* may be NULL */
 }
diff --git a/src/core/ext/transport/chttp2/server/chttp2_server.c b/src/core/ext/transport/chttp2/server/chttp2_server.c
index 86f5a198c2..574d1a7710 100644
--- a/src/core/ext/transport/chttp2/server/chttp2_server.c
+++ b/src/core/ext/transport/chttp2/server/chttp2_server.c
@@ -46,6 +46,7 @@
 #include "src/core/ext/transport/chttp2/transport/chttp2_transport.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/channel/http_server_filter.h"
 #include "src/core/lib/iomgr/endpoint.h"
 #include "src/core/lib/iomgr/resolve_address.h"
@@ -54,24 +55,6 @@
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/server.h"
 
-void grpc_chttp2_server_handshaker_factory_add_handshakers(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory,
-    grpc_handshake_manager *handshake_mgr) {
-  if (handshaker_factory != NULL) {
-    handshaker_factory->vtable->add_handshakers(exec_ctx, handshaker_factory,
-                                                handshake_mgr);
-  }
-}
-
-void grpc_chttp2_server_handshaker_factory_destroy(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory) {
-  if (handshaker_factory != NULL) {
-    handshaker_factory->vtable->destroy(exec_ctx, handshaker_factory);
-  }
-}
-
 typedef struct pending_handshake_manager_node {
   grpc_handshake_manager *handshake_mgr;
   struct pending_handshake_manager_node *next;
@@ -81,7 +64,6 @@ typedef struct {
   grpc_server *server;
   grpc_tcp_server *tcp_server;
   grpc_channel_args *args;
-  grpc_chttp2_server_handshaker_factory *handshaker_factory;
   gpr_mu mu;
   bool shutdown;
   grpc_closure tcp_server_shutdown_complete;
@@ -198,8 +180,8 @@ static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, grpc_endpoint *tcp,
   connection_state->accepting_pollset = accepting_pollset;
   connection_state->acceptor = acceptor;
   connection_state->handshake_mgr = handshake_mgr;
-  grpc_chttp2_server_handshaker_factory_add_handshakers(
-      exec_ctx, state->handshaker_factory, connection_state->handshake_mgr);
+  grpc_handshakers_add(exec_ctx, HANDSHAKER_SERVER, state->args,
+                       connection_state->handshake_mgr);
   // TODO(roth): We should really get this timeout value from channel
   // args instead of hard-coding it.
   const gpr_timespec deadline = gpr_time_add(
@@ -233,8 +215,6 @@ static void tcp_server_shutdown_complete(grpc_exec_ctx *exec_ctx, void *arg,
   // Flush queued work before destroying handshaker factory, since that
   // may do a synchronous unref.
   grpc_exec_ctx_flush(exec_ctx);
-  grpc_chttp2_server_handshaker_factory_destroy(exec_ctx,
-                                                state->handshaker_factory);
   if (destroy_done != NULL) {
     destroy_done->cb(exec_ctx, destroy_done->cb_arg, GRPC_ERROR_REF(error));
     grpc_exec_ctx_flush(exec_ctx);
@@ -259,10 +239,10 @@ static void server_destroy_listener(grpc_exec_ctx *exec_ctx,
   grpc_tcp_server_unref(exec_ctx, tcp_server);
 }
 
-grpc_error *grpc_chttp2_server_add_port(
-    grpc_exec_ctx *exec_ctx, grpc_server *server, const char *addr,
-    grpc_channel_args *args,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory, int *port_num) {
+grpc_error *grpc_chttp2_server_add_port(grpc_exec_ctx *exec_ctx,
+                                        grpc_server *server, const char *addr,
+                                        grpc_channel_args *args,
+                                        int *port_num) {
   grpc_resolved_addresses *resolved = NULL;
   grpc_tcp_server *tcp_server = NULL;
   size_t i;
@@ -293,7 +273,6 @@ grpc_error *grpc_chttp2_server_add_port(
   state->server = server;
   state->tcp_server = tcp_server;
   state->args = args;
-  state->handshaker_factory = handshaker_factory;
   state->shutdown = true;
   gpr_mu_init(&state->mu);
 
@@ -348,7 +327,6 @@ error:
     grpc_tcp_server_unref(exec_ctx, tcp_server);
   } else {
     grpc_channel_args_destroy(exec_ctx, args);
-    grpc_chttp2_server_handshaker_factory_destroy(exec_ctx, handshaker_factory);
     gpr_free(state);
   }
   *port_num = 0;
diff --git a/src/core/ext/transport/chttp2/server/chttp2_server.h b/src/core/ext/transport/chttp2/server/chttp2_server.h
index aa364b565d..2581ebaae9 100644
--- a/src/core/ext/transport/chttp2/server/chttp2_server.h
+++ b/src/core/ext/transport/chttp2/server/chttp2_server.h
@@ -36,43 +36,12 @@
 
 #include <grpc/impl/codegen/grpc_types.h>
 
-#include "src/core/lib/channel/handshaker.h"
 #include "src/core/lib/iomgr/exec_ctx.h"
 
-/// A server handshaker factory is used to create handshakers for server
-/// connections.
-typedef struct grpc_chttp2_server_handshaker_factory
-    grpc_chttp2_server_handshaker_factory;
-
-typedef struct {
-  void (*add_handshakers)(
-      grpc_exec_ctx *exec_ctx,
-      grpc_chttp2_server_handshaker_factory *handshaker_factory,
-      grpc_handshake_manager *handshake_mgr);
-  void (*destroy)(grpc_exec_ctx *exec_ctx,
-                  grpc_chttp2_server_handshaker_factory *handshaker_factory);
-} grpc_chttp2_server_handshaker_factory_vtable;
-
-struct grpc_chttp2_server_handshaker_factory {
-  const grpc_chttp2_server_handshaker_factory_vtable *vtable;
-};
-
-void grpc_chttp2_server_handshaker_factory_add_handshakers(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory,
-    grpc_handshake_manager *handshake_mgr);
-
-void grpc_chttp2_server_handshaker_factory_destroy(
-    grpc_exec_ctx *exec_ctx,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory);
-
 /// Adds a port to \a server.  Sets \a port_num to the port number.
-/// If \a handshaker_factory is not NULL, it will be used to create
-/// handshakers for the port.
-/// Takes ownership of \a args and \a handshaker_factory.
-grpc_error *grpc_chttp2_server_add_port(
-    grpc_exec_ctx *exec_ctx, grpc_server *server, const char *addr,
-    grpc_channel_args *args,
-    grpc_chttp2_server_handshaker_factory *handshaker_factory, int *port_num);
+/// Takes ownership of \a args.
+grpc_error *grpc_chttp2_server_add_port(grpc_exec_ctx *exec_ctx,
+                                        grpc_server *server, const char *addr,
+                                        grpc_channel_args *args, int *port_num);
 
 #endif /* GRPC_CORE_EXT_TRANSPORT_CHTTP2_SERVER_CHTTP2_SERVER_H */
diff --git a/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c b/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c
index 7e286d4e46..bf5026bea6 100644
--- a/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c
+++ b/src/core/ext/transport/chttp2/server/insecure/server_chttp2.c
@@ -47,8 +47,7 @@ int grpc_server_add_insecure_http2_port(grpc_server *server, const char *addr) {
                  (server, addr));
   grpc_error *err = grpc_chttp2_server_add_port(
       &exec_ctx, server, addr,
-      grpc_channel_args_copy(grpc_server_get_channel_args(server)),
-      NULL /* handshaker_factory */, &port_num);
+      grpc_channel_args_copy(grpc_server_get_channel_args(server)), &port_num);
   if (err != GRPC_ERROR_NONE) {
     const char *msg = grpc_error_string(err);
     gpr_log(GPR_ERROR, "%s", msg);
diff --git a/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c b/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c
index b5e4996b16..395c79a71d 100644
--- a/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c
+++ b/src/core/ext/transport/chttp2/server/secure/server_secure_chttp2.c
@@ -49,34 +49,6 @@
 #include "src/core/lib/surface/api_trace.h"
 #include "src/core/lib/surface/server.h"
 
-typedef struct {
-  grpc_chttp2_server_handshaker_factory base;
-  grpc_server_security_connector *security_connector;
-} server_security_handshaker_factory;
-
-static void server_security_handshaker_factory_add_handshakers(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_server_handshaker_factory *hf,
-    grpc_handshake_manager *handshake_mgr) {
-  server_security_handshaker_factory *handshaker_factory =
-      (server_security_handshaker_factory *)hf;
-  grpc_server_security_connector_add_handshakers(
-      exec_ctx, handshaker_factory->security_connector, handshake_mgr);
-}
-
-static void server_security_handshaker_factory_destroy(
-    grpc_exec_ctx *exec_ctx, grpc_chttp2_server_handshaker_factory *hf) {
-  server_security_handshaker_factory *handshaker_factory =
-      (server_security_handshaker_factory *)hf;
-  GRPC_SECURITY_CONNECTOR_UNREF(
-      exec_ctx, &handshaker_factory->security_connector->base, "server");
-  gpr_free(hf);
-}
-
-static const grpc_chttp2_server_handshaker_factory_vtable
-    server_security_handshaker_factory_vtable = {
-        server_security_handshaker_factory_add_handshakers,
-        server_security_handshaker_factory_destroy};
-
 int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
                                       grpc_server_credentials *creds) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
@@ -105,20 +77,19 @@ int grpc_server_add_secure_http2_port(grpc_server *server, const char *addr,
     gpr_free(msg);
     goto done;
   }
-  // Create handshaker factory.
-  server_security_handshaker_factory *handshaker_factory =
-      gpr_malloc(sizeof(*handshaker_factory));
-  memset(handshaker_factory, 0, sizeof(*handshaker_factory));
-  handshaker_factory->base.vtable = &server_security_handshaker_factory_vtable;
-  handshaker_factory->security_connector = sc;
   // Create channel args.
-  grpc_arg channel_arg = grpc_server_credentials_to_arg(creds);
-  grpc_channel_args *args = grpc_channel_args_copy_and_add(
-      grpc_server_get_channel_args(server), &channel_arg, 1);
+  grpc_arg args_to_add[2];
+  args_to_add[0] = grpc_server_credentials_to_arg(creds);
+  args_to_add[1] = grpc_security_connector_to_arg(&sc->base);
+  grpc_channel_args *args =
+      grpc_channel_args_copy_and_add(grpc_server_get_channel_args(server),
+                                     args_to_add, GPR_ARRAY_SIZE(args_to_add));
   // Add server port.
-  err = grpc_chttp2_server_add_port(&exec_ctx, server, addr, args,
-                                    &handshaker_factory->base, &port_num);
+  err = grpc_chttp2_server_add_port(&exec_ctx, server, addr, args, &port_num);
 done:
+  if (sc != NULL) {
+    GRPC_SECURITY_CONNECTOR_UNREF(&exec_ctx, &sc->base, "server");
+  }
   grpc_exec_ctx_finish(&exec_ctx);
   if (err != GRPC_ERROR_NONE) {
     const char *msg = grpc_error_string(err);
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 827c99c1d1..339d2138c6 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -47,6 +47,7 @@
 #include "src/core/ext/transport/chttp2/transport/http2_errors.h"
 #include "src/core/ext/transport/chttp2/transport/internal.h"
 #include "src/core/ext/transport/chttp2/transport/status_conversion.h"
+#include "src/core/ext/transport/chttp2/transport/varint.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/http/parser.h"
 #include "src/core/lib/iomgr/workqueue.h"
@@ -1689,8 +1690,9 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
 
     if (optional_message != NULL) {
       size_t msg_len = strlen(optional_message);
-      GPR_ASSERT(msg_len < 127);
-      message_pfx = grpc_slice_malloc(15);
+      GPR_ASSERT(msg_len <= UINT32_MAX);
+      uint32_t msg_len_len = GRPC_CHTTP2_VARINT_LENGTH((uint32_t)msg_len, 0);
+      message_pfx = grpc_slice_malloc(14 + msg_len_len);
       p = GRPC_SLICE_START_PTR(message_pfx);
       *p++ = 0x40;
       *p++ = 12; /* len(grpc-message) */
@@ -1706,7 +1708,9 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
       *p++ = 'a';
       *p++ = 'g';
       *p++ = 'e';
-      *p++ = (uint8_t)msg_len;
+      GRPC_CHTTP2_WRITE_VARINT((uint32_t)msg_len, 0, 0, p,
+                               (uint32_t)msg_len_len);
+      p += msg_len_len;
       GPR_ASSERT(p == GRPC_SLICE_END_PTR(message_pfx));
       len += (uint32_t)GRPC_SLICE_LENGTH(message_pfx);
       len += (uint32_t)msg_len;
diff --git a/src/core/ext/transport/chttp2/transport/frame_rst_stream.c b/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
index b4c5ed769b..20043f5fbf 100644
--- a/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
+++ b/src/core/ext/transport/chttp2/transport/frame_rst_stream.c
@@ -109,7 +109,7 @@ grpc_error *grpc_chttp2_rst_stream_parser_parse(grpc_exec_ctx *exec_ctx,
                       (((uint32_t)p->reason_bytes[2]) << 8) |
                       (((uint32_t)p->reason_bytes[3]));
     grpc_error *error = GRPC_ERROR_NONE;
-    if (reason != GRPC_CHTTP2_NO_ERROR) {
+    if (reason != GRPC_CHTTP2_NO_ERROR || s->header_frames_received < 2) {
       error = grpc_error_set_int(GRPC_ERROR_CREATE("RST_STREAM"),
                                  GRPC_ERROR_INT_HTTP2_ERROR, (intptr_t)reason);
       grpc_status_code status_code = grpc_chttp2_http2_error_to_grpc_status(
diff --git a/src/core/lib/README.md b/src/core/lib/README.md
new file mode 100644
index 0000000000..69b6bce2d9
--- /dev/null
+++ b/src/core/lib/README.md
@@ -0,0 +1,6 @@
+Required elements of gRPC Core: Each module in this directory is required to
+build gRPC. If it's possible to envisage a configuration where code is not
+required, then that code belongs in ext/ instead.
+
+NOTE: The movement of code between lib and ext is an ongoing effort, so this
+directory currently contains too much of the core library.
diff --git a/src/core/lib/channel/README.md b/src/core/lib/channel/README.md
new file mode 100644
index 0000000000..2dfcfe6e66
--- /dev/null
+++ b/src/core/lib/channel/README.md
@@ -0,0 +1,4 @@
+# Channel
+
+Provides channel/call stack implementation, and implementation of common filters
+for that implementation.
diff --git a/src/core/lib/channel/deadline_filter.c b/src/core/lib/channel/deadline_filter.c
index 8dd6d099e1..a45a4d4b82 100644
--- a/src/core/lib/channel/deadline_filter.c
+++ b/src/core/lib/channel/deadline_filter.c
@@ -83,8 +83,11 @@ static void start_timer_if_needed_locked(grpc_exec_ctx* exec_ctx,
     // Take a reference to the call stack, to be owned by the timer.
     GRPC_CALL_STACK_REF(deadline_state->call_stack, "deadline_timer");
     deadline_state->timer_pending = true;
-    grpc_timer_init(exec_ctx, &deadline_state->timer, deadline, timer_callback,
-                    elem, gpr_now(GPR_CLOCK_MONOTONIC));
+    grpc_closure_init(&deadline_state->timer_callback, timer_callback, elem,
+                      grpc_schedule_on_exec_ctx);
+    grpc_timer_init(exec_ctx, &deadline_state->timer, deadline,
+                    &deadline_state->timer_callback,
+                    gpr_now(GPR_CLOCK_MONOTONIC));
   }
 }
 static void start_timer_if_needed(grpc_exec_ctx* exec_ctx,
diff --git a/src/core/lib/channel/deadline_filter.h b/src/core/lib/channel/deadline_filter.h
index 716a852565..bd2b84f79e 100644
--- a/src/core/lib/channel/deadline_filter.h
+++ b/src/core/lib/channel/deadline_filter.h
@@ -46,6 +46,7 @@ typedef struct grpc_deadline_state {
   bool timer_pending;
   // The deadline timer.
   grpc_timer timer;
+  grpc_closure timer_callback;
   // Closure to invoke when the call is complete.
   // We use this to cancel the timer.
   grpc_closure on_complete;
diff --git a/src/core/lib/channel/handshaker.c b/src/core/lib/channel/handshaker.c
index ff827527b3..c052ca5385 100644
--- a/src/core/lib/channel/handshaker.c
+++ b/src/core/lib/channel/handshaker.c
@@ -86,6 +86,7 @@ struct grpc_handshake_manager {
   grpc_tcp_server_acceptor* acceptor;
   // Deadline timer across all handshakers.
   grpc_timer deadline_timer;
+  grpc_closure on_timeout;
   // The final callback and user_data to invoke after the last handshaker.
   grpc_closure on_handshake_done;
   void* user_data;
@@ -224,9 +225,11 @@ void grpc_handshake_manager_do_handshake(
                     grpc_schedule_on_exec_ctx);
   // Start deadline timer, which owns a ref.
   gpr_ref(&mgr->refs);
+  grpc_closure_init(&mgr->on_timeout, on_timeout, mgr,
+                    grpc_schedule_on_exec_ctx);
   grpc_timer_init(exec_ctx, &mgr->deadline_timer,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  on_timeout, mgr, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &mgr->on_timeout, gpr_now(GPR_CLOCK_MONOTONIC));
   // Start first handshaker, which also owns a ref.
   gpr_ref(&mgr->refs);
   bool done = call_next_handshaker_locked(exec_ctx, mgr, GRPC_ERROR_NONE);
diff --git a/src/core/lib/channel/handshaker_factory.c b/src/core/lib/channel/handshaker_factory.c
new file mode 100644
index 0000000000..3c30a4e1d2
--- /dev/null
+++ b/src/core/lib/channel/handshaker_factory.c
@@ -0,0 +1,54 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/channel/handshaker_factory.h"
+
+#include <grpc/support/log.h>
+
+void grpc_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr) {
+  if (handshaker_factory != NULL) {
+    GPR_ASSERT(handshaker_factory->vtable != NULL);
+    handshaker_factory->vtable->add_handshakers(exec_ctx, handshaker_factory,
+                                                args, handshake_mgr);
+  }
+}
+
+void grpc_handshaker_factory_destroy(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory) {
+  if (handshaker_factory != NULL) {
+    GPR_ASSERT(handshaker_factory->vtable != NULL);
+    handshaker_factory->vtable->destroy(exec_ctx, handshaker_factory);
+  }
+}
diff --git a/src/core/lib/channel/handshaker_factory.h b/src/core/lib/channel/handshaker_factory.h
new file mode 100644
index 0000000000..1984546104
--- /dev/null
+++ b/src/core/lib/channel/handshaker_factory.h
@@ -0,0 +1,66 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CHANNEL_HANDSHAKER_FACTORY_H
+#define GRPC_CORE_LIB_CHANNEL_HANDSHAKER_FACTORY_H
+
+#include <grpc/impl/codegen/grpc_types.h>
+
+#include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
+
+// A handshaker factory is used to create handshakers.
+
+typedef struct grpc_handshaker_factory grpc_handshaker_factory;
+
+typedef struct {
+  void (*add_handshakers)(grpc_exec_ctx *exec_ctx,
+                          grpc_handshaker_factory *handshaker_factory,
+                          const grpc_channel_args *args,
+                          grpc_handshake_manager *handshake_mgr);
+  void (*destroy)(grpc_exec_ctx *exec_ctx,
+                  grpc_handshaker_factory *handshaker_factory);
+} grpc_handshaker_factory_vtable;
+
+struct grpc_handshaker_factory {
+  const grpc_handshaker_factory_vtable *vtable;
+};
+
+void grpc_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr);
+
+void grpc_handshaker_factory_destroy(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory);
+
+#endif /* GRPC_CORE_LIB_CHANNEL_HANDSHAKER_FACTORY_H */
diff --git a/src/core/lib/channel/handshaker_registry.c b/src/core/lib/channel/handshaker_registry.c
new file mode 100644
index 0000000000..2e5f04064c
--- /dev/null
+++ b/src/core/lib/channel/handshaker_registry.c
@@ -0,0 +1,113 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/lib/channel/handshaker_registry.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+
+//
+// grpc_handshaker_factory_list
+//
+
+typedef struct {
+  grpc_handshaker_factory** list;
+  size_t num_factories;
+} grpc_handshaker_factory_list;
+
+static void grpc_handshaker_factory_list_register(
+    grpc_handshaker_factory_list* list, bool at_start,
+    grpc_handshaker_factory* factory) {
+  list->list = gpr_realloc(
+      list->list, (list->num_factories + 1) * sizeof(grpc_handshaker_factory*));
+  if (at_start) {
+    memmove(list->list + 1, list->list,
+            sizeof(grpc_handshaker_factory*) * list->num_factories);
+    list->list[0] = factory;
+  } else {
+    list->list[list->num_factories] = factory;
+  }
+  ++list->num_factories;
+}
+
+static void grpc_handshaker_factory_list_add_handshakers(
+    grpc_exec_ctx* exec_ctx, grpc_handshaker_factory_list* list,
+    const grpc_channel_args* args, grpc_handshake_manager* handshake_mgr) {
+  for (size_t i = 0; i < list->num_factories; ++i) {
+    grpc_handshaker_factory_add_handshakers(exec_ctx, list->list[i], args,
+                                            handshake_mgr);
+  }
+}
+
+static void grpc_handshaker_factory_list_destroy(
+    grpc_exec_ctx* exec_ctx, grpc_handshaker_factory_list* list) {
+  for (size_t i = 0; i < list->num_factories; ++i) {
+    grpc_handshaker_factory_destroy(exec_ctx, list->list[i]);
+  }
+  gpr_free(list->list);
+}
+
+//
+// plugin
+//
+
+static grpc_handshaker_factory_list
+    g_handshaker_factory_lists[NUM_HANDSHAKER_TYPES];
+
+void grpc_handshaker_factory_registry_init() {
+  memset(g_handshaker_factory_lists, 0, sizeof(g_handshaker_factory_lists));
+}
+
+void grpc_handshaker_factory_registry_shutdown(grpc_exec_ctx* exec_ctx) {
+  for (size_t i = 0; i < NUM_HANDSHAKER_TYPES; ++i) {
+    grpc_handshaker_factory_list_destroy(exec_ctx,
+                                         &g_handshaker_factory_lists[i]);
+  }
+}
+
+void grpc_handshaker_factory_register(bool at_start,
+                                      grpc_handshaker_type handshaker_type,
+                                      grpc_handshaker_factory* factory) {
+  grpc_handshaker_factory_list_register(
+      &g_handshaker_factory_lists[handshaker_type], at_start, factory);
+}
+
+void grpc_handshakers_add(grpc_exec_ctx* exec_ctx,
+                          grpc_handshaker_type handshaker_type,
+                          const grpc_channel_args* args,
+                          grpc_handshake_manager* handshake_mgr) {
+  grpc_handshaker_factory_list_add_handshakers(
+      exec_ctx, &g_handshaker_factory_lists[handshaker_type], args,
+      handshake_mgr);
+}
diff --git a/src/core/lib/channel/handshaker_registry.h b/src/core/lib/channel/handshaker_registry.h
new file mode 100644
index 0000000000..53c1b173af
--- /dev/null
+++ b/src/core/lib/channel/handshaker_registry.h
@@ -0,0 +1,63 @@
+/*
+ *
+ * Copyright 2016, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_LIB_CHANNEL_HANDSHAKER_REGISTRY_H
+#define GRPC_CORE_LIB_CHANNEL_HANDSHAKER_REGISTRY_H
+
+#include <grpc/impl/codegen/grpc_types.h>
+
+#include "src/core/lib/channel/handshaker_factory.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
+
+typedef enum {
+  HANDSHAKER_CLIENT = 0,
+  HANDSHAKER_SERVER,
+  NUM_HANDSHAKER_TYPES,  // Must be last.
+} grpc_handshaker_type;
+
+void grpc_handshaker_factory_registry_init();
+void grpc_handshaker_factory_registry_shutdown(grpc_exec_ctx* exec_ctx);
+
+/// Registers a new handshaker factory.  Takes ownership.
+/// If \a at_start is true, the new handshaker will be at the beginning of
+/// the list.  Otherwise, it will be added to the end.
+void grpc_handshaker_factory_register(bool at_start,
+                                      grpc_handshaker_type handshaker_type,
+                                      grpc_handshaker_factory* factory);
+
+void grpc_handshakers_add(grpc_exec_ctx* exec_ctx,
+                          grpc_handshaker_type handshaker_type,
+                          const grpc_channel_args* args,
+                          grpc_handshake_manager* handshake_mgr);
+
+#endif /* GRPC_CORE_LIB_CHANNEL_HANDSHAKER_REGISTRY_H */
diff --git a/src/core/lib/iomgr/README.md b/src/core/lib/iomgr/README.md
new file mode 100644
index 0000000000..9b22b76ceb
--- /dev/null
+++ b/src/core/lib/iomgr/README.md
@@ -0,0 +1,6 @@
+# iomgr
+
+Platform abstractions for I/O (mostly network).
+
+Provides abstractions over TCP/UDP I/O, file loading, polling, and concurrency
+management for various operating systems.
diff --git a/src/core/lib/iomgr/iocp_windows.c b/src/core/lib/iomgr/iocp_windows.c
index 60ebe43676..f0f4a6ff39 100644
--- a/src/core/lib/iomgr/iocp_windows.c
+++ b/src/core/lib/iomgr/iocp_windows.c
@@ -80,7 +80,6 @@ grpc_iocp_work_status grpc_iocp_work(grpc_exec_ctx *exec_ctx,
   LPOVERLAPPED overlapped;
   grpc_winsocket *socket;
   grpc_winsocket_callback_info *info;
-  grpc_closure *closure = NULL;
   success = GetQueuedCompletionStatus(
       g_iocp, &bytes, &completion_key, &overlapped,
       deadline_to_millis_timeout(deadline, gpr_now(deadline.clock_type)));
diff --git a/src/core/lib/iomgr/tcp_client_posix.c b/src/core/lib/iomgr/tcp_client_posix.c
index c8237dc38f..9a77c92016 100644
--- a/src/core/lib/iomgr/tcp_client_posix.c
+++ b/src/core/lib/iomgr/tcp_client_posix.c
@@ -65,6 +65,7 @@ typedef struct {
   grpc_fd *fd;
   gpr_timespec deadline;
   grpc_timer alarm;
+  grpc_closure on_alarm;
   int refs;
   grpc_closure write_closure;
   grpc_pollset_set *interested_parties;
@@ -352,9 +353,10 @@ static void tcp_client_connect_impl(grpc_exec_ctx *exec_ctx,
   }
 
   gpr_mu_lock(&ac->mu);
+  grpc_closure_init(&ac->on_alarm, tc_on_alarm, ac, grpc_schedule_on_exec_ctx);
   grpc_timer_init(exec_ctx, &ac->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  tc_on_alarm, ac, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &ac->on_alarm, gpr_now(GPR_CLOCK_MONOTONIC));
   grpc_fd_notify_on_write(exec_ctx, ac->fd, &ac->write_closure);
   gpr_mu_unlock(&ac->mu);
 
diff --git a/src/core/lib/iomgr/tcp_client_uv.c b/src/core/lib/iomgr/tcp_client_uv.c
index ed0de50fc1..5225a5402b 100644
--- a/src/core/lib/iomgr/tcp_client_uv.c
+++ b/src/core/lib/iomgr/tcp_client_uv.c
@@ -49,6 +49,7 @@
 typedef struct grpc_uv_tcp_connect {
   uv_connect_t connect_req;
   grpc_timer alarm;
+  grpc_closure on_alarm;
   uv_tcp_t *tcp_handle;
   grpc_closure *closure;
   grpc_endpoint **endpoint;
@@ -148,9 +149,11 @@ static void tcp_client_connect_impl(grpc_exec_ctx *exec_ctx,
   uv_tcp_connect(&connect->connect_req, connect->tcp_handle,
                  (const struct sockaddr *)resolved_addr->addr,
                  uv_tc_on_connect);
+  grpc_closure_init(&connect->on_alarm, uv_tc_on_alarm, connect,
+                    grpc_schedule_on_exec_ctx);
   grpc_timer_init(exec_ctx, &connect->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  uv_tc_on_alarm, connect, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &connect->on_alarm, gpr_now(GPR_CLOCK_MONOTONIC));
 }
 
 // overridden by api_fuzzer.c
diff --git a/src/core/lib/iomgr/tcp_client_windows.c b/src/core/lib/iomgr/tcp_client_windows.c
index 275258ebb5..1e84ec3a1e 100644
--- a/src/core/lib/iomgr/tcp_client_windows.c
+++ b/src/core/lib/iomgr/tcp_client_windows.c
@@ -58,6 +58,7 @@ typedef struct {
   grpc_winsocket *socket;
   gpr_timespec deadline;
   grpc_timer alarm;
+  grpc_closure on_alarm;
   char *addr_name;
   int refs;
   grpc_closure on_connect;
@@ -229,7 +230,8 @@ void grpc_tcp_client_connect(grpc_exec_ctx *exec_ctx, grpc_closure *on_done,
   ac->resource_quota = resource_quota;
   grpc_closure_init(&ac->on_connect, on_connect, ac, grpc_schedule_on_exec_ctx);
 
-  grpc_timer_init(exec_ctx, &ac->alarm, deadline, on_alarm, ac,
+  grpc_closure_init(&ac->on_alarm, on_alarm, ac, grpc_schedule_on_exec_ctx);
+  grpc_timer_init(exec_ctx, &ac->alarm, deadline, &ac->on_alarm,
                   gpr_now(GPR_CLOCK_MONOTONIC));
   grpc_socket_notify_on_write(exec_ctx, socket, &ac->on_connect);
   return;
diff --git a/src/core/lib/iomgr/tcp_server_windows.c b/src/core/lib/iomgr/tcp_server_windows.c
index 97d7827461..dafe851ce8 100644
--- a/src/core/lib/iomgr/tcp_server_windows.c
+++ b/src/core/lib/iomgr/tcp_server_windows.c
@@ -184,7 +184,6 @@ void grpc_tcp_server_shutdown_starting_add(grpc_tcp_server *s,
 }
 
 static void tcp_server_destroy(grpc_exec_ctx *exec_ctx, grpc_tcp_server *s) {
-  int immediately_done = 0;
   grpc_tcp_listener *sp;
   gpr_mu_lock(&s->mu);
 
@@ -240,7 +239,7 @@ static grpc_error *prepare_socket(SOCKET sock,
     error = GRPC_WSA_ERROR(WSAGetLastError(), "getsockname");
     goto failure;
   }
-  sockname_temp.len = sockname_temp_len;
+  sockname_temp.len = (size_t)sockname_temp_len;
 
   *port = grpc_sockaddr_get_port(&sockname_temp);
   return GRPC_ERROR_NONE;
@@ -248,7 +247,7 @@ static grpc_error *prepare_socket(SOCKET sock,
 failure:
   GPR_ASSERT(error != GRPC_ERROR_NONE);
   char *tgtaddr = grpc_sockaddr_to_uri(addr);
-  grpc_error *final_error = grpc_error_set_int(
+  grpc_error_set_int(
       grpc_error_set_str(GRPC_ERROR_CREATE_REFERENCING(
                              "Failed to prepare server socket", &error, 1),
                          GRPC_ERROR_STR_TARGET_ADDRESS, tgtaddr),
@@ -261,7 +260,6 @@ failure:
 
 static void decrement_active_ports_and_notify_locked(grpc_exec_ctx *exec_ctx,
                                                      grpc_tcp_listener *sp) {
-  int notify = 0;
   sp->shutting_down = 0;
   GPR_ASSERT(sp->server->active_ports > 0);
   if (0 == --sp->server->active_ports) {
@@ -375,7 +373,7 @@ static void on_accept(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
       int peer_name_len = (int)peer_name.len;
       err =
           getpeername(sock, (struct sockaddr *)peer_name.addr, &peer_name_len);
-      peer_name.len = peer_name_len;
+      peer_name.len = (size_t)peer_name_len;
       if (!err) {
         peer_name_string = grpc_sockaddr_to_uri(&peer_name);
       } else {
@@ -498,7 +496,7 @@ grpc_error *grpc_tcp_server_add_port(grpc_tcp_server *s,
       if (0 == getsockname(sp->socket->socket,
                            (struct sockaddr *)sockname_temp.addr,
                            &sockname_temp_len)) {
-        sockname_temp.len = sockname_temp_len;
+        sockname_temp.len = (size_t)sockname_temp_len;
         *port = grpc_sockaddr_get_port(&sockname_temp);
         if (*port > 0) {
           allocated_addr = gpr_malloc(sizeof(grpc_resolved_address));
diff --git a/src/core/lib/iomgr/timer.h b/src/core/lib/iomgr/timer.h
index 20fe98c4a7..d84a278b18 100644
--- a/src/core/lib/iomgr/timer.h
+++ b/src/core/lib/iomgr/timer.h
@@ -49,15 +49,15 @@
 
 typedef struct grpc_timer grpc_timer;
 
-/* Initialize *timer. When expired or canceled, timer_cb will be called with
-   *timer_cb_arg and error set to indicate if it expired (GRPC_ERROR_NONE) or
-   was canceled (GRPC_ERROR_CANCELLED). timer_cb is guaranteed to be called
-   exactly once, and application code should check the error to determine
-   how it was invoked. The application callback is also responsible for
-   maintaining information about when to free up any user-level state. */
+/* Initialize *timer. When expired or canceled, closure will be called with
+   error set to indicate if it expired (GRPC_ERROR_NONE) or was canceled
+   (GRPC_ERROR_CANCELLED). timer_cb is guaranteed to be called exactly once, and
+   application code should check the error to determine how it was invoked. The
+   application callback is also responsible for maintaining information about
+   when to free up any user-level state. */
 void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
-                     gpr_timespec deadline, grpc_iomgr_cb_func timer_cb,
-                     void *timer_cb_arg, gpr_timespec now);
+                     gpr_timespec deadline, grpc_closure *closure,
+                     gpr_timespec now);
 
 /* Note that there is no timer destroy function. This is because the
    timer is a one-time occurrence with a guarantee that the callback will
diff --git a/src/core/lib/iomgr/timer_generic.c b/src/core/lib/iomgr/timer_generic.c
index ecd3b284dc..40c8351472 100644
--- a/src/core/lib/iomgr/timer_generic.c
+++ b/src/core/lib/iomgr/timer_generic.c
@@ -178,28 +178,27 @@ static void note_deadline_change(shard_type *shard) {
 }
 
 void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
-                     gpr_timespec deadline, grpc_iomgr_cb_func timer_cb,
-                     void *timer_cb_arg, gpr_timespec now) {
+                     gpr_timespec deadline, grpc_closure *closure,
+                     gpr_timespec now) {
   int is_first_timer = 0;
   shard_type *shard = &g_shards[shard_idx(timer)];
   GPR_ASSERT(deadline.clock_type == g_clock_type);
   GPR_ASSERT(now.clock_type == g_clock_type);
-  grpc_closure_init(&timer->closure, timer_cb, timer_cb_arg,
-                    grpc_schedule_on_exec_ctx);
+  timer->closure = closure;
   timer->deadline = deadline;
   timer->triggered = 0;
 
   if (!g_initialized) {
     timer->triggered = 1;
     grpc_closure_sched(
-        exec_ctx, &timer->closure,
+        exec_ctx, timer->closure,
         GRPC_ERROR_CREATE("Attempt to create timer before initialization"));
     return;
   }
 
   if (gpr_time_cmp(deadline, now) <= 0) {
     timer->triggered = 1;
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_NONE);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_NONE);
     return;
   }
 
@@ -251,7 +250,7 @@ void grpc_timer_cancel(grpc_exec_ctx *exec_ctx, grpc_timer *timer) {
   shard_type *shard = &g_shards[shard_idx(timer)];
   gpr_mu_lock(&shard->mu);
   if (!timer->triggered) {
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_CANCELLED);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_CANCELLED);
     timer->triggered = 1;
     if (timer->heap_index == INVALID_HEAP_INDEX) {
       list_remove(timer);
@@ -317,7 +316,7 @@ static size_t pop_timers(grpc_exec_ctx *exec_ctx, shard_type *shard,
   grpc_timer *timer;
   gpr_mu_lock(&shard->mu);
   while ((timer = pop_one(shard, now))) {
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_REF(error));
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_REF(error));
     n++;
   }
   *new_min_deadline = compute_min_deadline(shard);
diff --git a/src/core/lib/iomgr/timer_generic.h b/src/core/lib/iomgr/timer_generic.h
index e4494adb5f..9d901c7e68 100644
--- a/src/core/lib/iomgr/timer_generic.h
+++ b/src/core/lib/iomgr/timer_generic.h
@@ -43,7 +43,7 @@ struct grpc_timer {
   int triggered;
   struct grpc_timer *next;
   struct grpc_timer *prev;
-  grpc_closure closure;
+  grpc_closure *closure;
 };
 
 #endif /* GRPC_CORE_LIB_IOMGR_TIMER_GENERIC_H */
diff --git a/src/core/lib/iomgr/timer_uv.c b/src/core/lib/iomgr/timer_uv.c
index 00b835ffb8..fa2cdee964 100644
--- a/src/core/lib/iomgr/timer_uv.c
+++ b/src/core/lib/iomgr/timer_uv.c
@@ -55,21 +55,20 @@ void run_expired_timer(uv_timer_t *handle) {
   grpc_exec_ctx exec_ctx = GRPC_EXEC_CTX_INIT;
   GPR_ASSERT(!timer->triggered);
   timer->triggered = 1;
-  grpc_closure_sched(&exec_ctx, &timer->closure, GRPC_ERROR_NONE);
+  grpc_closure_sched(&exec_ctx, timer->closure, GRPC_ERROR_NONE);
   stop_uv_timer(handle);
   grpc_exec_ctx_finish(&exec_ctx);
 }
 
 void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
-                     gpr_timespec deadline, grpc_iomgr_cb_func timer_cb,
-                     void *timer_cb_arg, gpr_timespec now) {
+                     gpr_timespec deadline, grpc_closure *closure,
+                     gpr_timespec now) {
   uint64_t timeout;
   uv_timer_t *uv_timer;
-  grpc_closure_init(&timer->closure, timer_cb, timer_cb_arg,
-                    grpc_schedule_on_exec_ctx);
+  timer->closure = closure;
   if (gpr_time_cmp(deadline, now) <= 0) {
     timer->triggered = 1;
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_NONE);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_NONE);
     return;
   }
   timer->triggered = 0;
@@ -84,7 +83,7 @@ void grpc_timer_init(grpc_exec_ctx *exec_ctx, grpc_timer *timer,
 void grpc_timer_cancel(grpc_exec_ctx *exec_ctx, grpc_timer *timer) {
   if (!timer->triggered) {
     timer->triggered = 1;
-    grpc_closure_sched(exec_ctx, &timer->closure, GRPC_ERROR_CANCELLED);
+    grpc_closure_sched(exec_ctx, timer->closure, GRPC_ERROR_CANCELLED);
     stop_uv_timer((uv_timer_t *)timer->uv_timer);
   }
 }
diff --git a/src/core/lib/iomgr/timer_uv.h b/src/core/lib/iomgr/timer_uv.h
index 3de383ebd5..13cf8bd4fa 100644
--- a/src/core/lib/iomgr/timer_uv.h
+++ b/src/core/lib/iomgr/timer_uv.h
@@ -37,7 +37,7 @@
 #include "src/core/lib/iomgr/exec_ctx.h"
 
 struct grpc_timer {
-  grpc_closure closure;
+  grpc_closure *closure;
   /* This is actually a uv_timer_t*, but we want to keep platform-specific
      types out of headers */
   void *uv_timer;
diff --git a/src/core/lib/security/transport/security_handshaker.c b/src/core/lib/security/transport/security_handshaker.c
index e886cc59a0..5e75856c7a 100644
--- a/src/core/lib/security/transport/security_handshaker.c
+++ b/src/core/lib/security/transport/security_handshaker.c
@@ -42,6 +42,7 @@
 
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/handshaker.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/security/context/security_context.h"
 #include "src/core/lib/security/transport/secure_endpoint.h"
 #include "src/core/lib/security/transport/tsi_error.h"
@@ -438,6 +439,45 @@ static grpc_handshaker *fail_handshaker_create() {
 }
 
 //
+// handshaker factories
+//
+
+static void client_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr) {
+  grpc_channel_security_connector *security_connector =
+      (grpc_channel_security_connector *)grpc_find_security_connector_in_args(
+          args);
+  grpc_channel_security_connector_add_handshakers(exec_ctx, security_connector,
+                                                  handshake_mgr);
+}
+
+static void server_handshaker_factory_add_handshakers(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *hf,
+    const grpc_channel_args *args, grpc_handshake_manager *handshake_mgr) {
+  grpc_server_security_connector *security_connector =
+      (grpc_server_security_connector *)grpc_find_security_connector_in_args(
+          args);
+  grpc_server_security_connector_add_handshakers(exec_ctx, security_connector,
+                                                 handshake_mgr);
+}
+
+static void handshaker_factory_destroy(
+    grpc_exec_ctx *exec_ctx, grpc_handshaker_factory *handshaker_factory) {}
+
+static const grpc_handshaker_factory_vtable client_handshaker_factory_vtable = {
+    client_handshaker_factory_add_handshakers, handshaker_factory_destroy};
+
+static grpc_handshaker_factory client_handshaker_factory = {
+    &client_handshaker_factory_vtable};
+
+static const grpc_handshaker_factory_vtable server_handshaker_factory_vtable = {
+    server_handshaker_factory_add_handshakers, handshaker_factory_destroy};
+
+static grpc_handshaker_factory server_handshaker_factory = {
+    &server_handshaker_factory_vtable};
+
+//
 // exported functions
 //
 
@@ -452,3 +492,10 @@ grpc_handshaker *grpc_security_handshaker_create(
     return security_handshaker_create(exec_ctx, handshaker, connector);
   }
 }
+
+void grpc_security_register_handshaker_factories() {
+  grpc_handshaker_factory_register(false /* at_start */, HANDSHAKER_CLIENT,
+                                   &client_handshaker_factory);
+  grpc_handshaker_factory_register(false /* at_start */, HANDSHAKER_SERVER,
+                                   &server_handshaker_factory);
+}
diff --git a/src/core/lib/security/transport/security_handshaker.h b/src/core/lib/security/transport/security_handshaker.h
index 5ddbf4b451..0b9eda178f 100644
--- a/src/core/lib/security/transport/security_handshaker.h
+++ b/src/core/lib/security/transport/security_handshaker.h
@@ -43,4 +43,7 @@ grpc_handshaker *grpc_security_handshaker_create(
     grpc_exec_ctx *exec_ctx, tsi_handshaker *handshaker,
     grpc_security_connector *connector);
 
+/// Registers security handshaker factories.
+void grpc_security_register_handshaker_factories();
+
 #endif /* GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_HANDSHAKER_H */
diff --git a/src/core/lib/surface/README.md b/src/core/lib/surface/README.md
new file mode 100644
index 0000000000..74cbd71131
--- /dev/null
+++ b/src/core/lib/surface/README.md
@@ -0,0 +1,4 @@
+# Surface
+
+Surface provides the bulk of the gRPC Core public API, and translates it into
+calls against core components.
diff --git a/src/core/lib/surface/alarm.c b/src/core/lib/surface/alarm.c
index aa9d60ee6a..e71c0ebfc5 100644
--- a/src/core/lib/surface/alarm.c
+++ b/src/core/lib/surface/alarm.c
@@ -38,6 +38,7 @@
 
 struct grpc_alarm {
   grpc_timer alarm;
+  grpc_closure on_alarm;
   grpc_cq_completion completion;
   /** completion queue where events about this alarm will be posted */
   grpc_completion_queue *cq;
@@ -64,9 +65,11 @@ grpc_alarm *grpc_alarm_create(grpc_completion_queue *cq, gpr_timespec deadline,
   alarm->tag = tag;
 
   grpc_cq_begin_op(cq, tag);
+  grpc_closure_init(&alarm->on_alarm, alarm_cb, alarm,
+                    grpc_schedule_on_exec_ctx);
   grpc_timer_init(&exec_ctx, &alarm->alarm,
                   gpr_convert_clock_type(deadline, GPR_CLOCK_MONOTONIC),
-                  alarm_cb, alarm, gpr_now(GPR_CLOCK_MONOTONIC));
+                  &alarm->on_alarm, gpr_now(GPR_CLOCK_MONOTONIC));
   grpc_exec_ctx_finish(&exec_ctx);
   return alarm;
 }
diff --git a/src/core/lib/surface/init.c b/src/core/lib/surface/init.c
index e20e602547..f61bf1582e 100644
--- a/src/core/lib/surface/init.c
+++ b/src/core/lib/surface/init.c
@@ -44,6 +44,7 @@
 #include "src/core/lib/channel/compress_filter.h"
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/channel/deadline_filter.h"
+#include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/channel/http_client_filter.h"
 #include "src/core/lib/channel/http_server_filter.h"
 #include "src/core/lib/channel/message_size_filter.h"
@@ -204,6 +205,8 @@ void grpc_init(void) {
     grpc_executor_init();
     gpr_timers_global_init();
     grpc_cq_global_init();
+    grpc_handshaker_factory_registry_init();
+    grpc_security_init();
     for (i = 0; i < g_number_of_plugins; i++) {
       if (g_all_of_the_plugins[i].init != NULL) {
         g_all_of_the_plugins[i].init();
@@ -238,6 +241,7 @@ void grpc_shutdown(void) {
       }
     }
     grpc_mdctx_global_shutdown(&exec_ctx);
+    grpc_handshaker_factory_registry_shutdown(&exec_ctx);
   }
   gpr_mu_unlock(&g_init_mu);
   grpc_exec_ctx_finish(&exec_ctx);
diff --git a/src/core/lib/surface/init.h b/src/core/lib/surface/init.h
index b1bf57c10d..3d1c528be0 100644
--- a/src/core/lib/surface/init.h
+++ b/src/core/lib/surface/init.h
@@ -36,6 +36,7 @@
 
 void grpc_register_security_filters(void);
 void grpc_security_pre_init(void);
+void grpc_security_init(void);
 int grpc_is_initialized(void);
 
 #endif /* GRPC_CORE_LIB_SURFACE_INIT_H */
diff --git a/src/core/lib/surface/init_secure.c b/src/core/lib/surface/init_secure.c
index 520a8aa84f..a44407d3bb 100644
--- a/src/core/lib/surface/init_secure.c
+++ b/src/core/lib/surface/init_secure.c
@@ -41,6 +41,7 @@
 #include "src/core/lib/security/transport/auth_filters.h"
 #include "src/core/lib/security/transport/secure_endpoint.h"
 #include "src/core/lib/security/transport/security_connector.h"
+#include "src/core/lib/security/transport/security_handshaker.h"
 #include "src/core/lib/surface/channel_init.h"
 #include "src/core/lib/tsi/transport_security_interface.h"
 
@@ -87,3 +88,5 @@ void grpc_register_security_filters(void) {
   grpc_channel_init_register_stage(GRPC_SERVER_CHANNEL, INT_MAX,
                                    maybe_prepend_server_auth_filter, NULL);
 }
+
+void grpc_security_init() { grpc_security_register_handshaker_factories(); }
diff --git a/src/core/lib/surface/init_unsecure.c b/src/core/lib/surface/init_unsecure.c
index f952739e0a..dbc9223ae0 100644
--- a/src/core/lib/surface/init_unsecure.c
+++ b/src/core/lib/surface/init_unsecure.c
@@ -36,3 +36,5 @@
 void grpc_security_pre_init(void) {}
 
 void grpc_register_security_filters(void) {}
+
+void grpc_security_init(void) {}
diff --git a/src/core/lib/transport/README.md b/src/core/lib/transport/README.md
new file mode 100644
index 0000000000..e7e135edeb
--- /dev/null
+++ b/src/core/lib/transport/README.md
@@ -0,0 +1,7 @@
+# Transport
+
+Common implementation details for gRPC Transports.
+
+Transports multiplex messages across some single connection. In ext/ there are
+implementations atop [a custom http2 implementation](/src/core/ext/transport/chttp2/README.md)
+and atop [cronet](/src/core/ext/transport/cronet/README.md).
diff --git a/src/core/lib/tsi/README.md b/src/core/lib/tsi/README.md
new file mode 100644
index 0000000000..3ca3c1ef38
--- /dev/null
+++ b/src/core/lib/tsi/README.md
@@ -0,0 +1,2 @@
+# Transport Security Interface
+An abstraction library over crypto and auth modules (typically OpenSSL)