server_headers.h

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/*
 * Copyright 2026 The A11 Authors
 *
 * 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
 *
 *     http://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.
 */
 
#ifndef A11_NET_SERVER_HEADERS_H_
#define A11_NET_SERVER_HEADERS_H_
 
#include <string>
#include <string_view>
 
#include <absl/status/status.h>
 
#include "a11/net/http2.h"
 
namespace a11::net {
 
inline constexpr std::string_view kServerHeaderValue = "a11";
 
struct CorsOptions {
  bool enabled = true;
  std::string allow_origin = "*";
  std::string allow_methods = "GET, POST, OPTIONS";
  std::string allow_headers = "content-type, accept, authorization, x-a11-*";
  std::string expose_headers = "x-a11-stream-id, x-a11-outbound";
  int max_age_seconds = 600;
 
  [[nodiscard]] absl::Status Validate() const;
};
 
enum class CachePolicy {
  kStream,
  kVolatile,
  kUnset,
};
 
struct ServerHeaderOptions {
  std::string server = std::string(kServerHeaderValue);
  CorsOptions cors;
  bool nosniff = true;
 
  [[nodiscard]] absl::Status Validate() const;
};
 
void ApplyServerHeaders(const ServerHeaderOptions& options, CachePolicy cache,
                        HttpHeaders* absl_nonnull headers);
 
[[nodiscard]] HttpHeaders CorsHeaders(const CorsOptions& options);
 
void ApplyCorsHeaders(const CorsOptions& options,
                      HttpHeaders* absl_nonnull headers);
 
[[nodiscard]] bool IsPreflight(const CorsOptions& options,
                               std::string_view method);
 
}  // namespace a11::net
 
#endif  // A11_NET_SERVER_HEADERS_H_