text: /**
   *
   * Copyright 2018 Google LLC
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   *
   */
  
  #include "net/grpc/gateway/nginx_utils.h"
  
  namespace grpc {
  namespace gateway {
  namespace {
  void AddElementToNginxElementTable(ngx_pool_t *pool, ngx_list_t *table,
                                     const string &name,
                                     const string_ref &value) {
    ngx_table_elt_t *ngx_key_value =
        reinterpret_cast<ngx_table_elt_t *>(ngx_list_push(table));
    if (ngx_key_value == nullptr) {
      ERROR("Failed to allocate response initial metadata for nginx.");
    }
    ngx_key_value->key.len = name.size();
    ngx_key_value->key.data =
        reinterpret_cast<u_char *>(ngx_palloc(pool, name.size()));
    ngx_copy(ngx_key_value->key.data, name.c_str(), name.size());
    ngx_key_value->value.len = value.size();
    ngx_key_value->value.data =
        reinterpret_cast<u_char *>(ngx_palloc(pool, value.size()));
    ngx_copy(ngx_key_value->value.data, value.data(), value.size());
    ngx_key_value->lowcase_key =
        reinterpret_cast<u_char *>(ngx_pnalloc(pool, ngx_key_value->key.len));
    ngx_strlow(ngx_key_value->lowcase_key, ngx_key_value->key.data,
               ngx_key_value->key.len);
    ngx_key_value->hash =
        ngx_hash_key_lc(ngx_key_value->key.data, ngx_key_value->key.len);
  }
  }  // namespace
  
  void AddHTTPHeader(ngx_http_request_t *http_request, const string &name,
                     const string_ref &value) {
    AddElementToNginxElementTable(
        http_request->pool, &http_request->headers_out.headers, name, value);
  }
  
  void AddHTTPTrailer(ngx_http_request_t *http_request, const string &name,
                      const string_ref &value) {
    AddElementToNginxElementTable(
        http_request->pool, &http_request->headers_out.trailers, name, value);
  }
  }  // namespace gateway
  }  // namespace grpc
  