Add proxy mapper hook.

5 files changed, 309 insertions, 6 deletions

diff --git a/src/core/ext/client_channel/proxy_mapper.c b/src/core/ext/client_channel/proxy_mapper.c
new file mode 100644
index 0000000000..11ce06bf1c
--- /dev/null
+++ b/src/core/ext/client_channel/proxy_mapper.c
@@ -0,0 +1,53 @@
+/*
+ *
+ * Copyright 2017, 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/ext/client_channel/proxy_mapper.h"
+
+void grpc_proxy_mapper_init(const grpc_proxy_mapper_vtable* vtable,
+                            grpc_proxy_mapper* mapper) {
+  mapper->vtable = vtable;
+}
+
+bool grpc_proxy_mapper_map(grpc_exec_ctx* exec_ctx, grpc_proxy_mapper* mapper,
+                           const grpc_resolved_address* address,
+                           const grpc_channel_args* args,
+                           grpc_resolved_address** new_address,
+                           grpc_channel_args** new_args) {
+  return mapper->vtable->map(exec_ctx, mapper, address, args, new_address,
+                             new_args);
+}
+
+void grpc_proxy_mapper_destroy(grpc_exec_ctx* exec_ctx,
+                               grpc_proxy_mapper* mapper) {
+  mapper->vtable->destroy(exec_ctx, mapper);
+}
diff --git a/src/core/ext/client_channel/proxy_mapper.h b/src/core/ext/client_channel/proxy_mapper.h
new file mode 100644
index 0000000000..a47a2f6e9d
--- /dev/null
+++ b/src/core/ext/client_channel/proxy_mapper.h
@@ -0,0 +1,74 @@
+/*
+ *
+ * Copyright 2017, 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_EXT_CLIENT_CHANNEL_PROXY_MAPPER_H
+#define GRPC_CORE_EXT_CLIENT_CHANNEL_PROXY_MAPPER_H
+
+#include <stdbool.h>
+
+#include <grpc/impl/codegen/grpc_types.h>
+
+#include "src/core/lib/iomgr/resolve_address.h"
+
+typedef struct grpc_proxy_mapper grpc_proxy_mapper;
+
+typedef struct {
+  /// Determines the proxy address to use to contact \a address.
+  /// If no proxy is needed, returns false.
+  /// Otherwise, sets \a new_address, optionally sets \a new_args, and
+  /// returns true.
+  bool (*map)(grpc_exec_ctx* exec_ctx, grpc_proxy_mapper* mapper,
+              const grpc_resolved_address* address,
+              const grpc_channel_args* args,
+              grpc_resolved_address** new_address,
+              grpc_channel_args** new_args);
+  /// Destroys \a mapper.
+  void (*destroy)(grpc_exec_ctx* exec_ctx, grpc_proxy_mapper* mapper);
+} grpc_proxy_mapper_vtable;
+
+struct grpc_proxy_mapper {
+  const grpc_proxy_mapper_vtable* vtable;
+};
+
+void grpc_proxy_mapper_init(const grpc_proxy_mapper_vtable* vtable,
+                            grpc_proxy_mapper* mapper);
+
+bool grpc_proxy_mapper_map(grpc_exec_ctx* exec_ctx, grpc_proxy_mapper* mapper,
+                           const grpc_resolved_address* address,
+                           const grpc_channel_args* args,
+                           grpc_resolved_address** new_address,
+                           grpc_channel_args** new_args);
+void grpc_proxy_mapper_destroy(grpc_exec_ctx* exec_ctx,
+                               grpc_proxy_mapper* mapper);
+
+#endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_PROXY_MAPPER_H */
diff --git a/src/core/ext/client_channel/proxy_mapper_registry.c b/src/core/ext/client_channel/proxy_mapper_registry.c
new file mode 100644
index 0000000000..ad453f272f
--- /dev/null
+++ b/src/core/ext/client_channel/proxy_mapper_registry.c
@@ -0,0 +1,110 @@
+/*
+ *
+ * Copyright 2017, 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/ext/client_channel/proxy_mapper_registry.h"
+
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+
+//
+// grpc_proxy_mapper_list
+//
+
+typedef struct {
+  grpc_proxy_mapper** list;
+  size_t num_mappers;
+} grpc_proxy_mapper_list;
+
+static void grpc_proxy_mapper_list_register(
+    grpc_proxy_mapper_list* list, bool at_start, grpc_proxy_mapper* mapper) {
+  list->list = gpr_realloc(
+      list->list, (list->num_mappers + 1) * sizeof(grpc_proxy_mapper*));
+  if (at_start) {
+    memmove(list->list + 1, list->list,
+            sizeof(grpc_proxy_mapper*) * list->num_mappers);
+    list->list[0] = mapper;
+  } else {
+    list->list[list->num_mappers] = mapper;
+  }
+  ++list->num_mappers;
+}
+
+static bool grpc_proxy_mapper_list_map(
+    grpc_exec_ctx* exec_ctx, grpc_proxy_mapper_list* list,
+    const grpc_resolved_address* address, const grpc_channel_args* args,
+    grpc_resolved_address** new_address, grpc_channel_args** new_args) {
+  for (size_t i = 0; i < list->num_mappers; ++i) {
+    if (grpc_proxy_mapper_map(exec_ctx, list->list[i], address, args,
+                              new_address, new_args)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+static void grpc_proxy_mapper_list_destroy(
+    grpc_exec_ctx* exec_ctx, grpc_proxy_mapper_list* list) {
+  for (size_t i = 0; i < list->num_mappers; ++i) {
+    grpc_proxy_mapper_destroy(exec_ctx, list->list[i]);
+  }
+  gpr_free(list->list);
+}
+
+//
+// plugin
+//
+
+static grpc_proxy_mapper_list g_proxy_mapper_list;
+
+void grpc_proxy_mapper_registry_init() {
+  memset(&g_proxy_mapper_list, 0, sizeof(g_proxy_mapper_list));
+}
+
+void grpc_proxy_mapper_registry_shutdown(grpc_exec_ctx* exec_ctx) {
+  grpc_proxy_mapper_list_destroy(exec_ctx, &g_proxy_mapper_list);
+}
+
+void grpc_proxy_mapper_factory_register(bool at_start,
+                                        grpc_proxy_mapper* mapper) {
+  grpc_proxy_mapper_list_register(&g_proxy_mapper_list, at_start, mapper);
+}
+
+bool grpc_proxy_mappers_map(grpc_exec_ctx* exec_ctx,
+                            const grpc_resolved_address* address,
+                            const grpc_channel_args* args,
+                            grpc_resolved_address** new_address,
+                            grpc_channel_args** new_args) {
+  return grpc_proxy_mapper_list_map(exec_ctx, &g_proxy_mapper_list, address,
+                                    args, new_address, new_args);
+}
diff --git a/src/core/ext/client_channel/proxy_mapper_registry.h b/src/core/ext/client_channel/proxy_mapper_registry.h
new file mode 100644
index 0000000000..4a4840d3b1
--- /dev/null
+++ b/src/core/ext/client_channel/proxy_mapper_registry.h
@@ -0,0 +1,54 @@
+/*
+ *
+ * Copyright 2017, 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_EXT_CLIENT_CHANNEL_PROXY_MAPPER_REGISTRY_H
+#define GRPC_CORE_EXT_CLIENT_CHANNEL_PROXY_MAPPER_REGISTRY_H
+
+#include "src/core/ext/client_channel/proxy_mapper.h"
+
+void grpc_proxy_mapper_registry_init();
+void grpc_proxy_mapper_registry_shutdown(grpc_exec_ctx* exec_ctx);
+
+/// Registers a new proxy mapper.  Takes ownership.
+/// If \a at_start is true, the new factory will be at the beginning of
+/// the list.  Otherwise, it will be added to the end.
+void grpc_proxy_mapper_factory_register(bool at_start,
+                                        grpc_proxy_mapper* mapper);
+
+bool grpc_proxy_mappers_map(grpc_exec_ctx* exec_ctx,
+                            const grpc_resolved_address* address,
+                            const grpc_channel_args* args,
+                            grpc_resolved_address** new_address,
+                            grpc_channel_args** new_args);
+
+#endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_PROXY_MAPPER_REGISTRY_H */
diff --git a/src/core/ext/client_channel/subchannel.c b/src/core/ext/client_channel/subchannel.c
index 8bd284507d..ff82a77255 100644
--- a/src/core/ext/client_channel/subchannel.c
+++ b/src/core/ext/client_channel/subchannel.c
@@ -43,6 +43,7 @@
 #include "src/core/ext/client_channel/client_channel.h"
 #include "src/core/ext/client_channel/initial_connect_string.h"
 #include "src/core/ext/client_channel/parse_address.h"
+#include "src/core/ext/client_channel/proxy_mapper_registry.h"
 #include "src/core/ext/client_channel/subchannel_index.h"
 #include "src/core/ext/client_channel/uri_parser.h"
 #include "src/core/lib/channel/channel_args.h"
@@ -332,13 +333,24 @@ grpc_subchannel *grpc_subchannel_create(grpc_exec_ctx *exec_ctx,
   grpc_resolved_address *addr = gpr_malloc(sizeof(*addr));
   grpc_get_subchannel_address_arg(args->args, addr);
   grpc_set_initial_connect_string(&addr, &c->initial_connect_string);
-  static const char *keys_to_remove[] = {GRPC_ARG_SUBCHANNEL_ADDRESS};
-  grpc_arg new_arg = grpc_create_subchannel_address_arg(addr);
+  grpc_resolved_address *new_address = NULL;
+  grpc_channel_args *new_args = NULL;
+  if (grpc_proxy_mappers_map(exec_ctx, c->addr, args->args, &new_address,
+                             &new_args)) {
+    GPR_ASSERT(new_address != NULL);
+    gpr_free(addr);
+    addr = new_address;
+    if (new_args != NULL) c->args = new_args;
+  }
+  if (c->args == NULL) {
+    static const char *keys_to_remove[] = {GRPC_ARG_SUBCHANNEL_ADDRESS};
+    grpc_arg new_arg = grpc_create_subchannel_address_arg(addr);
+    c->args = grpc_channel_args_copy_and_add_and_remove(
+        args->args, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove), &new_arg,
+        1);
+    gpr_free(new_arg.value.string);
+  }
   gpr_free(addr);
-  c->args = grpc_channel_args_copy_and_add_and_remove(
-      args->args, keys_to_remove, GPR_ARRAY_SIZE(keys_to_remove), &new_arg, 1);
-  gpr_free(new_arg.value.string);
-
   c->root_external_state_watcher.next = c->root_external_state_watcher.prev =
       &c->root_external_state_watcher;
   grpc_closure_init(&c->connected, subchannel_connected, c,