Merge branch 'master' into node_generator_nested_messages

9 files changed, 435 insertions, 40 deletions

diff --git a/src/core/lib/channel/channel_args.h b/src/core/lib/channel/channel_args.h
index 653d04f427..aec61ee7c6 100644
--- a/src/core/lib/channel/channel_args.h
+++ b/src/core/lib/channel/channel_args.h
@@ -37,6 +37,8 @@
 #include <grpc/compression.h>
 #include <grpc/grpc.h>
 
+// Channel args are intentionally immutable, to avoid the need for locking.
+
 /** Copy the arguments in \a src into a new instance */
 grpc_channel_args *grpc_channel_args_copy(const grpc_channel_args *src);
 
diff --git a/src/core/lib/channel/channel_stack.c b/src/core/lib/channel/channel_stack.c
index 42075b127b..98f304f2da 100644
--- a/src/core/lib/channel/channel_stack.c
+++ b/src/core/lib/channel/channel_stack.c
@@ -157,12 +157,13 @@ void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
   }
 }
 
-void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
-                          grpc_channel_stack *channel_stack, int initial_refs,
-                          grpc_iomgr_cb_func destroy, void *destroy_arg,
-                          grpc_call_context_element *context,
-                          const void *transport_server_data,
-                          grpc_call_stack *call_stack) {
+grpc_error *grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
+                                 grpc_channel_stack *channel_stack,
+                                 int initial_refs, grpc_iomgr_cb_func destroy,
+                                 void *destroy_arg,
+                                 grpc_call_context_element *context,
+                                 const void *transport_server_data,
+                                 grpc_call_stack *call_stack) {
   grpc_channel_element *channel_elems = CHANNEL_ELEMS_FROM_STACK(channel_stack);
   grpc_call_element_args args;
   size_t count = channel_stack->count;
@@ -178,6 +179,7 @@ void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
               ROUND_UP_TO_ALIGNMENT_SIZE(count * sizeof(grpc_call_element));
 
   /* init per-filter data */
+  grpc_error *first_error = GRPC_ERROR_NONE;
   for (i = 0; i < count; i++) {
     args.call_stack = call_stack;
     args.server_transport_data = transport_server_data;
@@ -185,10 +187,19 @@ void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
     call_elems[i].filter = channel_elems[i].filter;
     call_elems[i].channel_data = channel_elems[i].channel_data;
     call_elems[i].call_data = user_data;
-    call_elems[i].filter->init_call_elem(exec_ctx, &call_elems[i], &args);
+    grpc_error *error =
+        call_elems[i].filter->init_call_elem(exec_ctx, &call_elems[i], &args);
+    if (error != GRPC_ERROR_NONE) {
+      if (first_error == GRPC_ERROR_NONE) {
+        first_error = error;
+      } else {
+        GRPC_ERROR_UNREF(error);
+      }
+    }
     user_data +=
         ROUND_UP_TO_ALIGNMENT_SIZE(call_elems[i].filter->sizeof_call_data);
   }
+  return first_error;
 }
 
 void grpc_call_stack_set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
@@ -217,7 +228,7 @@ void grpc_call_stack_ignore_set_pollset_or_pollset_set(
     grpc_polling_entity *pollent) {}
 
 void grpc_call_stack_destroy(grpc_exec_ctx *exec_ctx, grpc_call_stack *stack,
-                             const grpc_call_stats *call_stats,
+                             const grpc_call_final_info *final_info,
                              void *and_free_memory) {
   grpc_call_element *elems = CALL_ELEMS_FROM_STACK(stack);
   size_t count = stack->count;
@@ -225,7 +236,7 @@ void grpc_call_stack_destroy(grpc_exec_ctx *exec_ctx, grpc_call_stack *stack,
 
   /* destroy per-filter data */
   for (i = 0; i < count; i++) {
-    elems[i].filter->destroy_call_elem(exec_ctx, &elems[i], call_stats,
+    elems[i].filter->destroy_call_elem(exec_ctx, &elems[i], final_info,
                                        i == count - 1 ? and_free_memory : NULL);
   }
 }
@@ -266,3 +277,14 @@ void grpc_call_element_send_cancel(grpc_exec_ctx *exec_ctx,
   op.cancel_error = GRPC_ERROR_CANCELLED;
   grpc_call_next_op(exec_ctx, cur_elem, &op);
 }
+
+void grpc_call_element_send_cancel_with_message(grpc_exec_ctx *exec_ctx,
+                                                grpc_call_element *cur_elem,
+                                                grpc_status_code status,
+                                                gpr_slice *optional_message) {
+  grpc_transport_stream_op op;
+  memset(&op, 0, sizeof(op));
+  grpc_transport_stream_op_add_cancellation_with_message(&op, status,
+                                                         optional_message);
+  grpc_call_next_op(exec_ctx, cur_elem, &op);
+}
diff --git a/src/core/lib/channel/channel_stack.h b/src/core/lib/channel/channel_stack.h
index 41dd4a0d8a..ee68701456 100644
--- a/src/core/lib/channel/channel_stack.h
+++ b/src/core/lib/channel/channel_stack.h
@@ -75,9 +75,14 @@ typedef struct {
 typedef struct {
   grpc_transport_stream_stats transport_stream_stats;
   gpr_timespec latency; /* From call creating to enqueing of received status */
-  grpc_status_code final_status;
 } grpc_call_stats;
 
+/** Information about the call upon completion. */
+typedef struct {
+  grpc_call_stats stats;
+  grpc_status_code final_status;
+} grpc_call_final_info;
+
 /* Channel filters specify:
    1. the amount of memory needed in the channel & call (via the sizeof_XXX
       members)
@@ -110,8 +115,9 @@ typedef struct {
      on a client; if it is non-NULL, then it points to memory owned by the
      transport and is on the server. Most filters want to ignore this
      argument. */
-  void (*init_call_elem)(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                         grpc_call_element_args *args);
+  grpc_error *(*init_call_elem)(grpc_exec_ctx *exec_ctx,
+                                grpc_call_element *elem,
+                                grpc_call_element_args *args);
   void (*set_pollset_or_pollset_set)(grpc_exec_ctx *exec_ctx,
                                      grpc_call_element *elem,
                                      grpc_polling_entity *pollent);
@@ -119,16 +125,17 @@ typedef struct {
      The filter does not need to do any chaining.
      The bottom filter of a stack will be passed a non-NULL pointer to
      \a and_free_memory that should be passed to gpr_free when destruction
-     is complete. */
+     is complete. \a final_info contains data about the completed call, mainly
+     for reporting purposes. */
   void (*destroy_call_elem)(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                            const grpc_call_stats *stats,
+                            const grpc_call_final_info *final_info,
                             void *and_free_memory);
 
   /* sizeof(per channel data) */
   size_t sizeof_channel_data;
   /* Initialize per-channel data.
-     elem is initialized at the start of the call, and elem->channel_data is
-     what needs initializing.
+     elem is initialized at the creating of the channel, and elem->channel_data
+     is what needs initializing.
      is_first, is_last designate this elements position in the stack, and are
      useful for asserting correct configuration by upper layer code.
      The filter does not need to do any chaining */
@@ -209,12 +216,13 @@ void grpc_channel_stack_destroy(grpc_exec_ctx *exec_ctx,
 /* Initialize a call stack given a channel stack. transport_server_data is
    expected to be NULL on a client, or an opaque transport owned pointer on the
    server. */
-void grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
-                          grpc_channel_stack *channel_stack, int initial_refs,
-                          grpc_iomgr_cb_func destroy, void *destroy_arg,
-                          grpc_call_context_element *context,
-                          const void *transport_server_data,
-                          grpc_call_stack *call_stack);
+grpc_error *grpc_call_stack_init(grpc_exec_ctx *exec_ctx,
+                                 grpc_channel_stack *channel_stack,
+                                 int initial_refs, grpc_iomgr_cb_func destroy,
+                                 void *destroy_arg,
+                                 grpc_call_context_element *context,
+                                 const void *transport_server_data,
+                                 grpc_call_stack *call_stack);
 /* Set a pollset or a pollset_set for a call stack: must occur before the first
  * op is started */
 void grpc_call_stack_set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
@@ -243,7 +251,7 @@ void grpc_call_stack_set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
 
 /* Destroy a call stack */
 void grpc_call_stack_destroy(grpc_exec_ctx *exec_ctx, grpc_call_stack *stack,
-                             const grpc_call_stats *call_stats,
+                             const grpc_call_final_info *final_info,
                              void *and_free_memory);
 
 /* Ignore set pollset{_set} - used by filters if they don't care about pollsets
@@ -273,6 +281,11 @@ void grpc_call_log_op(char *file, int line, gpr_log_severity severity,
 void grpc_call_element_send_cancel(grpc_exec_ctx *exec_ctx,
                                    grpc_call_element *cur_elem);
 
+void grpc_call_element_send_cancel_with_message(grpc_exec_ctx *exec_ctx,
+                                                grpc_call_element *cur_elem,
+                                                grpc_status_code status,
+                                                gpr_slice *optional_message);
+
 extern int grpc_trace_channel;
 
 #define GRPC_CALL_LOG_OP(sev, elem, op) \
diff --git a/src/core/lib/channel/compress_filter.c b/src/core/lib/channel/compress_filter.c
index 32ebe53ee6..134180e619 100644
--- a/src/core/lib/channel/compress_filter.c
+++ b/src/core/lib/channel/compress_filter.c
@@ -256,8 +256,9 @@ static void compress_start_transport_stream_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
 
@@ -266,11 +267,14 @@ static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
   calld->has_compression_algorithm = 0;
   grpc_closure_init(&calld->got_slice, got_slice, elem);
   grpc_closure_init(&calld->send_done, send_done, elem);
+
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                              const grpc_call_stats *stats, void *ignored) {
+                              const grpc_call_final_info *final_info,
+                              void *ignored) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   gpr_slice_buffer_destroy(&calld->slices);
diff --git a/src/core/lib/channel/connected_channel.c b/src/core/lib/channel/connected_channel.c
index 0a7d27a1dc..918379c845 100644
--- a/src/core/lib/channel/connected_channel.c
+++ b/src/core/lib/channel/connected_channel.c
@@ -81,16 +81,16 @@ static void con_start_transport_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
-  int r;
-
-  r = grpc_transport_init_stream(
+  int r = grpc_transport_init_stream(
       exec_ctx, chand->transport, TRANSPORT_STREAM_FROM_CALL_DATA(calld),
       &args->call_stack->refcount, args->server_transport_data);
-  GPR_ASSERT(r == 0);
+  return r == 0 ? GRPC_ERROR_NONE
+                : GRPC_ERROR_CREATE("transport stream initialization failed");
 }
 
 static void set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
@@ -104,7 +104,7 @@ static void set_pollset_or_pollset_set(grpc_exec_ctx *exec_ctx,
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                              const grpc_call_stats *stats,
+                              const grpc_call_final_info *final_info,
                               void *and_free_memory) {
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
diff --git a/src/core/lib/channel/handshaker.c b/src/core/lib/channel/handshaker.c
new file mode 100644
index 0000000000..6c3ca198b7
--- /dev/null
+++ b/src/core/lib/channel/handshaker.c
@@ -0,0 +1,197 @@
+/*
+ *
+ * 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 <string.h>
+
+#include <grpc/impl/codegen/alloc.h>
+#include <grpc/impl/codegen/log.h>
+
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/handshaker.h"
+
+//
+// grpc_handshaker
+//
+
+void grpc_handshaker_init(const struct grpc_handshaker_vtable* vtable,
+                          grpc_handshaker* handshaker) {
+  handshaker->vtable = vtable;
+}
+
+void grpc_handshaker_destroy(grpc_exec_ctx* exec_ctx,
+                             grpc_handshaker* handshaker) {
+  handshaker->vtable->destroy(exec_ctx, handshaker);
+}
+
+void grpc_handshaker_shutdown(grpc_exec_ctx* exec_ctx,
+                              grpc_handshaker* handshaker) {
+  handshaker->vtable->shutdown(exec_ctx, handshaker);
+}
+
+void grpc_handshaker_do_handshake(grpc_exec_ctx* exec_ctx,
+                                  grpc_handshaker* handshaker,
+                                  grpc_endpoint* endpoint,
+                                  grpc_channel_args* args,
+                                  gpr_timespec deadline,
+                                  grpc_tcp_server_acceptor* acceptor,
+                                  grpc_handshaker_done_cb cb, void* user_data) {
+  handshaker->vtable->do_handshake(exec_ctx, handshaker, endpoint, args,
+                                   deadline, acceptor, cb, user_data);
+}
+
+//
+// grpc_handshake_manager
+//
+
+// State used while chaining handshakers.
+struct grpc_handshaker_state {
+  // The index of the handshaker to invoke next.
+  size_t index;
+  // The deadline for all handshakers.
+  gpr_timespec deadline;
+  // The acceptor to call the handshakers with.
+  grpc_tcp_server_acceptor* acceptor;
+  // The final callback and user_data to invoke after the last handshaker.
+  grpc_handshaker_done_cb final_cb;
+  void* final_user_data;
+};
+
+struct grpc_handshake_manager {
+  // An array of handshakers added via grpc_handshake_manager_add().
+  size_t count;
+  grpc_handshaker** handshakers;
+  // State used while chaining handshakers.
+  struct grpc_handshaker_state* state;
+};
+
+grpc_handshake_manager* grpc_handshake_manager_create() {
+  grpc_handshake_manager* mgr = gpr_malloc(sizeof(grpc_handshake_manager));
+  memset(mgr, 0, sizeof(*mgr));
+  return mgr;
+}
+
+static bool is_power_of_2(size_t n) { return (n & (n - 1)) == 0; }
+
+void grpc_handshake_manager_add(grpc_handshake_manager* mgr,
+                                grpc_handshaker* handshaker) {
+  // To avoid allocating memory for each handshaker we add, we double
+  // the number of elements every time we need more.
+  size_t realloc_count = 0;
+  if (mgr->count == 0) {
+    realloc_count = 2;
+  } else if (mgr->count >= 2 && is_power_of_2(mgr->count)) {
+    realloc_count = mgr->count * 2;
+  }
+  if (realloc_count > 0) {
+    mgr->handshakers =
+        gpr_realloc(mgr->handshakers, realloc_count * sizeof(grpc_handshaker*));
+  }
+  mgr->handshakers[mgr->count++] = handshaker;
+}
+
+void grpc_handshake_manager_destroy(grpc_exec_ctx* exec_ctx,
+                                    grpc_handshake_manager* mgr) {
+  for (size_t i = 0; i < mgr->count; ++i) {
+    grpc_handshaker_destroy(exec_ctx, mgr->handshakers[i]);
+  }
+  gpr_free(mgr->handshakers);
+  gpr_free(mgr);
+}
+
+void grpc_handshake_manager_shutdown(grpc_exec_ctx* exec_ctx,
+                                     grpc_handshake_manager* mgr) {
+  for (size_t i = 0; i < mgr->count; ++i) {
+    grpc_handshaker_shutdown(exec_ctx, mgr->handshakers[i]);
+  }
+  if (mgr->state != NULL) {
+    gpr_free(mgr->state);
+    mgr->state = NULL;
+  }
+}
+
+// A function used as the handshaker-done callback when chaining
+// handshakers together.
+static void call_next_handshaker(grpc_exec_ctx* exec_ctx,
+                                 grpc_endpoint* endpoint,
+                                 grpc_channel_args* args, void* user_data,
+                                 grpc_error* error) {
+  grpc_handshake_manager* mgr = user_data;
+  GPR_ASSERT(mgr->state != NULL);
+  GPR_ASSERT(mgr->state->index < mgr->count);
+  // If we got an error, skip all remaining handshakers and invoke the
+  // caller-supplied callback immediately.
+  if (error != GRPC_ERROR_NONE) {
+    mgr->state->final_cb(exec_ctx, endpoint, args, mgr->state->final_user_data,
+                         error);
+    return;
+  }
+  grpc_handshaker_done_cb cb = call_next_handshaker;
+  // If this is the last handshaker, use the caller-supplied callback
+  // and user_data instead of chaining back to this function again.
+  if (mgr->state->index == mgr->count - 1) {
+    cb = mgr->state->final_cb;
+    user_data = mgr->state->final_user_data;
+  }
+  // Invoke handshaker.
+  grpc_handshaker_do_handshake(exec_ctx, mgr->handshakers[mgr->state->index],
+                               endpoint, args, mgr->state->deadline,
+                               mgr->state->acceptor, cb, user_data);
+  ++mgr->state->index;
+  // If this is the last handshaker, clean up state.
+  if (mgr->state->index == mgr->count) {
+    gpr_free(mgr->state);
+    mgr->state = NULL;
+  }
+}
+
+void grpc_handshake_manager_do_handshake(
+    grpc_exec_ctx* exec_ctx, grpc_handshake_manager* mgr,
+    grpc_endpoint* endpoint, const grpc_channel_args* args,
+    gpr_timespec deadline, grpc_tcp_server_acceptor* acceptor,
+    grpc_handshaker_done_cb cb, void* user_data) {
+  grpc_channel_args* args_copy = grpc_channel_args_copy(args);
+  if (mgr->count == 0) {
+    // No handshakers registered, so we just immediately call the done
+    // callback with the passed-in endpoint.
+    cb(exec_ctx, endpoint, args_copy, user_data, GRPC_ERROR_NONE);
+  } else {
+    GPR_ASSERT(mgr->state == NULL);
+    mgr->state = gpr_malloc(sizeof(struct grpc_handshaker_state));
+    memset(mgr->state, 0, sizeof(*mgr->state));
+    mgr->state->deadline = deadline;
+    mgr->state->acceptor = acceptor;
+    mgr->state->final_cb = cb;
+    mgr->state->final_user_data = user_data;
+    call_next_handshaker(exec_ctx, endpoint, args_copy, mgr, GRPC_ERROR_NONE);
+  }
+}
diff --git a/src/core/lib/channel/handshaker.h b/src/core/lib/channel/handshaker.h
new file mode 100644
index 0000000000..dfc469c417
--- /dev/null
+++ b/src/core/lib/channel/handshaker.h
@@ -0,0 +1,145 @@
+/*
+ *
+ * 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_H
+#define GRPC_CORE_LIB_CHANNEL_HANDSHAKER_H
+
+#include <grpc/impl/codegen/grpc_types.h>
+#include <grpc/impl/codegen/time.h>
+
+#include "src/core/lib/iomgr/closure.h"
+#include "src/core/lib/iomgr/endpoint.h"
+#include "src/core/lib/iomgr/exec_ctx.h"
+#include "src/core/lib/iomgr/tcp_server.h"
+
+/// Handshakers are used to perform initial handshakes on a connection
+/// before the client sends the initial request.  Some examples of what
+/// a handshaker can be used for includes support for HTTP CONNECT on
+/// the client side and various types of security initialization.
+///
+/// In general, handshakers should be used via a handshake manager.
+
+///
+/// grpc_handshaker
+///
+
+typedef struct grpc_handshaker grpc_handshaker;
+
+/// Callback type invoked when a handshaker is done.
+/// Takes ownership of \a args.
+typedef void (*grpc_handshaker_done_cb)(grpc_exec_ctx* exec_ctx,
+                                        grpc_endpoint* endpoint,
+                                        grpc_channel_args* args,
+                                        void* user_data, grpc_error* error);
+
+struct grpc_handshaker_vtable {
+  /// Destroys the handshaker.
+  void (*destroy)(grpc_exec_ctx* exec_ctx, grpc_handshaker* handshaker);
+
+  /// Shuts down the handshaker (e.g., to clean up when the operation is
+  /// aborted in the middle).
+  void (*shutdown)(grpc_exec_ctx* exec_ctx, grpc_handshaker* handshaker);
+
+  /// Performs handshaking.  When finished, calls \a cb with \a user_data.
+  /// Takes ownership of \a args.
+  /// \a acceptor will be NULL for client-side handshakers.
+  void (*do_handshake)(grpc_exec_ctx* exec_ctx, grpc_handshaker* handshaker,
+                       grpc_endpoint* endpoint, grpc_channel_args* args,
+                       gpr_timespec deadline,
+                       grpc_tcp_server_acceptor* acceptor,
+                       grpc_handshaker_done_cb cb, void* user_data);
+};
+
+/// Base struct.  To subclass, make this the first member of the
+/// implementation struct.
+struct grpc_handshaker {
+  const struct grpc_handshaker_vtable* vtable;
+};
+
+/// Called by concrete implementations to initialize the base struct.
+void grpc_handshaker_init(const struct grpc_handshaker_vtable* vtable,
+                          grpc_handshaker* handshaker);
+
+/// Convenient wrappers for invoking methods via the vtable.
+/// These probably do not need to be called from anywhere but
+/// grpc_handshake_manager.
+void grpc_handshaker_destroy(grpc_exec_ctx* exec_ctx,
+                             grpc_handshaker* handshaker);
+void grpc_handshaker_shutdown(grpc_exec_ctx* exec_ctx,
+                              grpc_handshaker* handshaker);
+void grpc_handshaker_do_handshake(grpc_exec_ctx* exec_ctx,
+                                  grpc_handshaker* handshaker,
+                                  grpc_endpoint* endpoint,
+                                  grpc_channel_args* args,
+                                  gpr_timespec deadline,
+                                  grpc_tcp_server_acceptor* acceptor,
+                                  grpc_handshaker_done_cb cb, void* user_data);
+
+///
+/// grpc_handshake_manager
+///
+
+typedef struct grpc_handshake_manager grpc_handshake_manager;
+
+/// Creates a new handshake manager.  Caller takes ownership.
+grpc_handshake_manager* grpc_handshake_manager_create();
+
+/// Adds a handshaker to the handshake manager.
+/// Takes ownership of \a handshaker.
+void grpc_handshake_manager_add(grpc_handshake_manager* mgr,
+                                grpc_handshaker* handshaker);
+
+/// Destroys the handshake manager.
+void grpc_handshake_manager_destroy(grpc_exec_ctx* exec_ctx,
+                                    grpc_handshake_manager* mgr);
+
+/// Shuts down the handshake manager (e.g., to clean up when the operation is
+/// aborted in the middle).
+/// The caller must still call grpc_handshake_manager_destroy() after
+/// calling this function.
+void grpc_handshake_manager_shutdown(grpc_exec_ctx* exec_ctx,
+                                     grpc_handshake_manager* mgr);
+
+/// Invokes handshakers in the order they were added.
+/// Does NOT take ownership of \a args.  Instead, makes a copy before
+/// invoking the first handshaker.
+/// \a acceptor will be NULL for client-side handshakers.
+/// Invokes \a cb with \a user_data after either a handshaker fails or
+/// all handshakers have completed successfully.
+void grpc_handshake_manager_do_handshake(
+    grpc_exec_ctx* exec_ctx, grpc_handshake_manager* mgr,
+    grpc_endpoint* endpoint, const grpc_channel_args* args,
+    gpr_timespec deadline, grpc_tcp_server_acceptor* acceptor,
+    grpc_handshaker_done_cb cb, void* user_data);
+
+#endif /* GRPC_CORE_LIB_CHANNEL_HANDSHAKER_H */
diff --git a/src/core/lib/channel/http_client_filter.c b/src/core/lib/channel/http_client_filter.c
index ab6c6c9ef0..a7a775cc53 100644
--- a/src/core/lib/channel/http_client_filter.c
+++ b/src/core/lib/channel/http_client_filter.c
@@ -76,7 +76,13 @@ static grpc_mdelem *client_recv_filter(void *user_data, grpc_mdelem *md) {
   if (md == GRPC_MDELEM_STATUS_200) {
     return NULL;
   } else if (md->key == GRPC_MDSTR_STATUS) {
-    grpc_call_element_send_cancel(a->exec_ctx, a->elem);
+    char *message_string;
+    gpr_asprintf(&message_string, "Received http2 header with status: %s",
+                 grpc_mdstr_as_c_string(md->value));
+    gpr_slice message = gpr_slice_from_copied_string(message_string);
+    gpr_free(message_string);
+    grpc_call_element_send_cancel_with_message(a->exec_ctx, a->elem,
+                                               GRPC_STATUS_CANCELLED, &message);
     return NULL;
   } else if (md == GRPC_MDELEM_CONTENT_TYPE_APPLICATION_SLASH_GRPC) {
     return NULL;
@@ -169,16 +175,19 @@ static void hc_start_transport_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   call_data *calld = elem->call_data;
   calld->on_done_recv = NULL;
   grpc_closure_init(&calld->hc_on_recv, hc_on_recv, elem);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                              const grpc_call_stats *stats, void *ignored) {}
+                              const grpc_call_final_info *final_info,
+                              void *ignored) {}
 
 static grpc_mdelem *scheme_from_args(const grpc_channel_args *args) {
   unsigned i;
diff --git a/src/core/lib/channel/http_server_filter.c b/src/core/lib/channel/http_server_filter.c
index d0beebd817..5ce51f9016 100644
--- a/src/core/lib/channel/http_server_filter.c
+++ b/src/core/lib/channel/http_server_filter.c
@@ -224,18 +224,21 @@ static void hs_start_transport_op(grpc_exec_ctx *exec_ctx,
 }
 
 /* Constructor for call_data */
-static void init_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                           grpc_call_element_args *args) {
+static grpc_error *init_call_elem(grpc_exec_ctx *exec_ctx,
+                                  grpc_call_element *elem,
+                                  grpc_call_element_args *args) {
   /* grab pointers to our data from the call element */
   call_data *calld = elem->call_data;
   /* initialize members */
   memset(calld, 0, sizeof(*calld));
   grpc_closure_init(&calld->hs_on_recv, hs_on_recv, elem);
+  return GRPC_ERROR_NONE;
 }
 
 /* Destructor for call_data */
 static void destroy_call_elem(grpc_exec_ctx *exec_ctx, grpc_call_element *elem,
-                              const grpc_call_stats *stats, void *ignored) {}
+                              const grpc_call_final_info *final_info,
+                              void *ignored) {}
 
 /* Constructor for channel_data */
 static void init_channel_elem(grpc_exec_ctx *exec_ctx,