websocket_signalling.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_WEBSOCKET_SIGNALLING_H_
#define A11_NET_WEBSOCKET_SIGNALLING_H_
 
#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
 
#include <absl/base/nullability.h>
#include <absl/status/status.h>
#include <absl/status/statusor.h>
#include <absl/time/time.h>
 
#include "a11/concurrency/future.h"
#include "a11/net/http2.h"
#include "a11/net/signalling.h"
 
namespace a11::net {
 
struct WebSocketSignallingClientOptions {
  Http2Options http2_options;  
  absl::Time deadline = absl::InfiniteFuture();
  size_t max_message_size = 1024 * 1024;  
  HttpHeaders headers;
 
  absl::Status Validate() const;
};
 
class WebSocketSignallingClient final
    : public SignallingTransport,
      public std::enable_shared_from_this<WebSocketSignallingClient> {
 private:
  struct State;
 
  struct ConstructorToken {};
 
 public:
  static a11::Future<std::shared_ptr<WebSocketSignallingClient>> Connect(
      std::string url, std::string identity,
      OnSignallingMessage on_message = {},
      WebSocketSignallingClientOptions options = {});
 
  ~WebSocketSignallingClient() override;
 
  absl::Status Send(SignallingMessage message) override;
  absl::Status SetOnMessage(OnSignallingMessage on_message) override;
  absl::Status Close() override;
  [[nodiscard]] std::string identity() const override;
  [[nodiscard]] bool connected() const override;
  [[nodiscard]] absl::Status GetStatus() const override;
  [[nodiscard]] void* absl_nullable GetImpl() const;
 
  explicit WebSocketSignallingClient(ConstructorToken,
                                     std::shared_ptr<State> state)
      : state_(std::move(state)) {}
 
 private:
  static void Pump(const std::shared_ptr<State>& state);
  static void Fail(const std::shared_ptr<State>& state, absl::Status status);
 
  std::shared_ptr<State> state_;
};
 
struct SignallingAdmission {
  std::string identity;  
  std::string path;      
  std::string query;     
  HttpHeaders headers;   
};
 
using OnSignallingAdmission = std::function<a11::Task(SignallingAdmission)>;
 
using OnSignallingDeparture = std::function<void(std::string identity)>;
 
using OnSignallingMessageFilter =
    std::function<absl::Status(SignallingMessage* absl_nonnull message)>;
 
using OnSignallingUnroutable =
    std::function<absl::Status(const SignallingMessage& message)>;
 
struct WebSocketSignallingServerOptions {
  std::string path_prefix =
      "/";  
  std::string bind_address = "127.0.0.1";  
  std::uint16_t port = 0;  
  Http2Options http2_options;             
  size_t max_message_size = 1024 * 1024;  
 
  OnSignallingAdmission on_admit;        
  OnSignallingDeparture on_departed;     
  OnSignallingMessageFilter on_message;  
  OnSignallingUnroutable on_unroutable;  
 
  bool replace_existing = false;
 
  absl::Status Validate() const;
};
 
class WebSocketSignallingServer
    : public std::enable_shared_from_this<WebSocketSignallingServer> {
 public:
  static absl::StatusOr<std::shared_ptr<WebSocketSignallingServer>> Create(
      std::shared_ptr<SignallingService> service,
      WebSocketSignallingServerOptions options = {});
 
  ~WebSocketSignallingServer();
 
  absl::Status Stop();
  absl::Status Disconnect(std::string_view identity);
  [[nodiscard]] std::uint16_t port() const;
  [[nodiscard]] bool running() const;
  [[nodiscard]] std::shared_ptr<SignallingService> service() const;
  [[nodiscard]] void* absl_nullable GetImpl() const;
 
 private:
  struct State;
 
  explicit WebSocketSignallingServer(std::shared_ptr<State> state)
      : state_(std::move(state)) {}
 
  static a11::Task Register(const std::shared_ptr<State>& state,
                            std::string identity, HttpRequest request,
                            std::shared_ptr<Http2ResponseWriter> response);
 
  static void Remove(const std::shared_ptr<State>& state,
                     const std::string& identity, std::uint64_t only = 0,
                     bool report = true);
 
  std::shared_ptr<State> state_;
};
 
}  // namespace a11::net
 
#endif  // A11_NET_WEBSOCKET_SIGNALLING_H_