Secure channels: use the right authority

2 files changed, 49 insertions, 39 deletions

diff --git a/src/core/lib/surface/channel.cc b/src/core/lib/surface/channel.cc
index 03353d6beb..48bc69509f 100644
--- a/src/core/lib/surface/channel.cc
+++ b/src/core/lib/surface/channel.cc
@@ -32,6 +32,7 @@
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/debug/stats.h"
 #include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/memory.h"
 #include "src/core/lib/iomgr/iomgr.h"
 #include "src/core/lib/slice/slice_internal.h"
 #include "src/core/lib/surface/api_trace.h"
@@ -55,7 +56,6 @@ typedef struct registered_call {
 struct grpc_channel {
   int is_client;
   grpc_compression_options compression_options;
-  grpc_mdelem default_authority;
 
   gpr_atm call_size_estimate;
 
@@ -108,40 +108,8 @@ grpc_channel* grpc_channel_create_with_builder(
 
   grpc_compression_options_init(&channel->compression_options);
   for (size_t i = 0; i < args->num_args; i++) {
-    if (0 == strcmp(args->args[i].key, GRPC_ARG_DEFAULT_AUTHORITY)) {
-      if (args->args[i].type != GRPC_ARG_STRING) {
-        gpr_log(GPR_ERROR, "%s ignored: it must be a string",
-                GRPC_ARG_DEFAULT_AUTHORITY);
-      } else {
-        if (!GRPC_MDISNULL(channel->default_authority)) {
-          /* setting this takes precedence over anything else */
-          GRPC_MDELEM_UNREF(channel->default_authority);
-        }
-        channel->default_authority = grpc_mdelem_from_slices(
-            GRPC_MDSTR_AUTHORITY,
-            grpc_slice_intern(
-                grpc_slice_from_static_string(args->args[i].value.string)));
-      }
-    } else if (0 ==
-               strcmp(args->args[i].key, GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)) {
-      if (args->args[i].type != GRPC_ARG_STRING) {
-        gpr_log(GPR_ERROR, "%s ignored: it must be a string",
-                GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
-      } else {
-        if (!GRPC_MDISNULL(channel->default_authority)) {
-          /* other ways of setting this (notably ssl) take precedence */
-          gpr_log(GPR_ERROR,
-                  "%s ignored: default host already set some other way",
-                  GRPC_SSL_TARGET_NAME_OVERRIDE_ARG);
-        } else {
-          channel->default_authority = grpc_mdelem_from_slices(
-              GRPC_MDSTR_AUTHORITY,
-              grpc_slice_intern(
-                  grpc_slice_from_static_string(args->args[i].value.string)));
-        }
-      }
-    } else if (0 == strcmp(args->args[i].key,
-                           GRPC_COMPRESSION_CHANNEL_DEFAULT_LEVEL)) {
+    if (0 ==
+        strcmp(args->args[i].key, GRPC_COMPRESSION_CHANNEL_DEFAULT_LEVEL)) {
       channel->compression_options.default_level.is_set = true;
       channel->compression_options.default_level.level =
           static_cast<grpc_compression_level>(grpc_channel_arg_get_integer(
@@ -169,12 +137,49 @@ done:
   return channel;
 }
 
+static grpc_core::UniquePtr<char> get_default_authority(
+    const char* target, const grpc_channel_args* input_args,
+    grpc_channel_stack_type channel_stack_type) {
+  bool has_default_authority = false;
+  char* ssl_override = nullptr;
+  grpc_core::UniquePtr<char> default_authority;
+  const size_t num_args = input_args != nullptr ? input_args->num_args : 0;
+  for (size_t i = 0; i < num_args; ++i) {
+    if (0 == strcmp(input_args->args[i].key, GRPC_ARG_DEFAULT_AUTHORITY)) {
+      has_default_authority = true;
+    } else if (0 == strcmp(input_args->args[i].key,
+                           GRPC_SSL_TARGET_NAME_OVERRIDE_ARG)) {
+      ssl_override = input_args->args[i].value.string;
+    }
+  }
+  if (!has_default_authority && ssl_override != nullptr) {
+    default_authority.reset(gpr_strdup(ssl_override));
+  }
+  return default_authority;
+}
+
+static grpc_channel_args* build_channel_args(
+    const grpc_channel_args* input_args, char* default_authority) {
+  grpc_arg new_args[1];
+  size_t num_new_args = 0;
+  if (default_authority != nullptr) {
+    new_args[num_new_args++] = grpc_channel_arg_string_create(
+        const_cast<char*>(GRPC_ARG_DEFAULT_AUTHORITY), default_authority);
+  }
+  return grpc_channel_args_copy_and_add(input_args, new_args, num_new_args);
+}
+
 grpc_channel* grpc_channel_create(const char* target,
                                   const grpc_channel_args* input_args,
                                   grpc_channel_stack_type channel_stack_type,
                                   grpc_transport* optional_transport) {
   grpc_channel_stack_builder* builder = grpc_channel_stack_builder_create();
-  grpc_channel_stack_builder_set_channel_arguments(builder, input_args);
+  const grpc_core::UniquePtr<char> default_authority =
+      get_default_authority(target, input_args, channel_stack_type);
+  grpc_channel_args* args =
+      build_channel_args(input_args, default_authority.get());
+  grpc_channel_stack_builder_set_channel_arguments(builder, args);
+  grpc_channel_args_destroy(args);
   grpc_channel_stack_builder_set_target(builder, target);
   grpc_channel_stack_builder_set_transport(builder, optional_transport);
   if (!grpc_channel_init_create_stack(builder, channel_stack_type)) {
@@ -246,8 +251,6 @@ static grpc_call* grpc_channel_create_call_internal(
   send_metadata[num_metadata++] = path_mdelem;
   if (!GRPC_MDISNULL(authority_mdelem)) {
     send_metadata[num_metadata++] = authority_mdelem;
-  } else if (!GRPC_MDISNULL(channel->default_authority)) {
-    send_metadata[num_metadata++] = GRPC_MDELEM_REF(channel->default_authority);
   }
 
   grpc_call_create_args args;
@@ -377,7 +380,6 @@ static void destroy_channel(void* arg, grpc_error* error) {
     GRPC_MDELEM_UNREF(rc->authority);
     gpr_free(rc);
   }
-  GRPC_MDELEM_UNREF(channel->default_authority);
   gpr_mu_destroy(&channel->registered_call_mu);
   gpr_free(channel->target);
   gpr_free(channel);
diff --git a/src/core/lib/surface/init.cc b/src/core/lib/surface/init.cc
index ac9f9e6066..10c65ce09f 100644
--- a/src/core/lib/surface/init.cc
+++ b/src/core/lib/surface/init.cc
@@ -27,6 +27,7 @@
 #include <grpc/support/log.h>
 #include <grpc/support/time.h>
 #include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/channel/client_authority_filter.h"
 #include "src/core/lib/channel/connected_channel.h"
 #include "src/core/lib/channel/handshaker_registry.h"
 #include "src/core/lib/debug/stats.h"
@@ -83,6 +84,13 @@ static bool prepend_filter(grpc_channel_stack_builder* builder, void* arg) {
 }
 
 static void register_builtin_channel_init() {
+  grpc_channel_init_register_stage(GRPC_CLIENT_SUBCHANNEL, INT_MAX,
+                                   prepend_filter,
+                                   (void*)(&grpc_client_authority_filter));
+  grpc_channel_init_register_stage(GRPC_CLIENT_DIRECT_CHANNEL, INT_MAX,
+                                   prepend_filter,
+                                   (void*)(&grpc_client_authority_filter));
+
   grpc_channel_init_register_stage(GRPC_CLIENT_SUBCHANNEL,
                                    GRPC_CHANNEL_INIT_BUILTIN_PRIORITY,
                                    grpc_add_connected_filter, nullptr);