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   1 /*
   2  *
   3  * Copyright 2017 gRPC authors.
   4  *
   5  * Licensed under the Apache License, Version 2.0 (the "License");
   6  * you may not use this file except in compliance with the License.
   7  * You may obtain a copy of the License at
   8  *
   9  *     http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  *
  17  */
  18
  19 #include <grpc/support/port_platform.h>
  20
  21 #include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_channel.h"
  22
  23 #include <string.h>
  24
  25 #include <grpc/support/alloc.h>
  26 #include <grpc/support/string_util.h>
  27
  28 #include "src/core/ext/filters/client_channel/client_channel.h"
  29 #include "src/core/ext/filters/client_channel/server_address.h"
  30 #include "src/core/lib/channel/channel_args.h"
  31 #include "src/core/lib/gpr/string.h"
  32 #include "src/core/lib/iomgr/sockaddr_utils.h"
  33 #include "src/core/lib/security/credentials/credentials.h"
  34 #include "src/core/lib/security/transport/target_authority_table.h"
  35 #include "src/core/lib/slice/slice_internal.h"
  36
  37 namespace grpc_core {
  38 namespace {
  39
  40 int BalancerNameCmp(const grpc_core::UniquePtr<char>& a,
  41                     const grpc_core::UniquePtr<char>& b) {
  42   return strcmp(a.get(), b.get());
  43 }
  44
  45 RefCountedPtr<TargetAuthorityTable> CreateTargetAuthorityTable(
  46     const ServerAddressList& addresses) {
  47   TargetAuthorityTable::Entry* target_authority_entries =
  48       static_cast<TargetAuthorityTable::Entry*>(
  49           gpr_zalloc(sizeof(*target_authority_entries) * addresses.size()));
  50   for (size_t i = 0; i < addresses.size(); ++i) {
  51     char* addr_str;
  52     GPR_ASSERT(
  53         grpc_sockaddr_to_string(&addr_str, &addresses[i].address(), true) > 0);
  54     target_authority_entries[i].key = grpc_slice_from_copied_string(addr_str);
  55     gpr_free(addr_str);
  56     char* balancer_name = grpc_channel_arg_get_string(grpc_channel_args_find(
  57         addresses[i].args(), GRPC_ARG_ADDRESS_BALANCER_NAME));
  58     target_authority_entries[i].value.reset(gpr_strdup(balancer_name));
  59   }
  60   RefCountedPtr<TargetAuthorityTable> target_authority_table =
  61       TargetAuthorityTable::Create(addresses.size(), target_authority_entries,
  62                                    BalancerNameCmp);
  63   gpr_free(target_authority_entries);
  64   return target_authority_table;
  65 }
  66
  67 }  // namespace
  68 }  // namespace grpc_core
  69
  70 grpc_channel_args* grpc_lb_policy_grpclb_modify_lb_channel_args(
  71     const grpc_core::ServerAddressList& addresses, grpc_channel_args* args) {
  72   const char* args_to_remove[1];
  73   size_t num_args_to_remove = 0;
  74   grpc_arg args_to_add[2];
  75   size_t num_args_to_add = 0;
  76   // Add arg for targets info table.
  77   grpc_core::RefCountedPtr<grpc_core::TargetAuthorityTable>
  78       target_authority_table = grpc_core::CreateTargetAuthorityTable(addresses);
  79   args_to_add[num_args_to_add++] =
  80       grpc_core::CreateTargetAuthorityTableChannelArg(
  81           target_authority_table.get());
  82   // Substitute the channel credentials with a version without call
  83   // credentials: the load balancer is not necessarily trusted to handle
  84   // bearer token credentials.
  85   grpc_channel_credentials* channel_credentials =
  86       grpc_channel_credentials_find_in_args(args);
  87   grpc_core::RefCountedPtr<grpc_channel_credentials> creds_sans_call_creds;
  88   if (channel_credentials != nullptr) {
  89     creds_sans_call_creds =
  90         channel_credentials->duplicate_without_call_credentials();
  91     GPR_ASSERT(creds_sans_call_creds != nullptr);
  92     args_to_remove[num_args_to_remove++] = GRPC_ARG_CHANNEL_CREDENTIALS;
  93     args_to_add[num_args_to_add++] =
  94         grpc_channel_credentials_to_arg(creds_sans_call_creds.get());
  95   }
  96   grpc_channel_args* result = grpc_channel_args_copy_and_add_and_remove(
  97       args, args_to_remove, num_args_to_remove, args_to_add, num_args_to_add);
  98   // Clean up.
  99   grpc_channel_args_destroy(args);
 100   return result;
 101 }