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https://github.com/nestriness/cdc-file-transfer.git
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26ff93489e
Instead of calling netstat locally to find out available ports in a tight range, call bind() with port zero to find an available ephemeral port. This is faster and much simpler, and will eventually help getting rid of PortManager. Also fixes issues with running SSH commands on Windows when the remote shell is Powershell (aka Backslash Bingo).
78 lines
2.7 KiB
C++
78 lines
2.7 KiB
C++
/*
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* Copyright 2022 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef COMMON_SERVER_SOCKET_H_
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#define COMMON_SERVER_SOCKET_H_
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#include "absl/status/status.h"
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#include "absl/status/statusor.h"
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#include "common/socket.h"
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struct addrinfo;
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namespace cdc_ft {
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class ServerSocket : public Socket {
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public:
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ServerSocket();
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~ServerSocket();
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// Returns an available ephemeral port that can be used as a listening port.
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// Note that calling this function, followed by StartListening() or similar,
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// is slightly racy as another process might use the port in the meantime.
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// However, the OS usually returns ephemeral ports in a round-robin manner,
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// and ports remain in TIME_WAIT state for a while, which may block other apps
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// from reusing the port. Hence, the chances of races are small. Nevertheless,
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// consider calling StartListening() with zero |port| if possible.
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static absl::StatusOr<int> FindAvailablePort();
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// Starts listening for connections on |port|.
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// Passing 0 as port will bind to any available port.
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// Returns the port that was bound to.
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absl::StatusOr<int> StartListening(int port);
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// Stops listening for connections. No-op if already stopped/never started.
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void StopListening();
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// Waits for a client to connect. Only supports one connection. Repeating
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// the call with an existing connection results in an error.
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absl::Status WaitForConnection();
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// Disconnects the client. No-op if not connected.
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void Disconnect();
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// Shuts down the sending end of the socket. This will interrupt any receive
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// calls on the client and shut it down.
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absl::Status ShutdownSendingEnd();
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// Socket:
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absl::Status Send(const void* buffer, size_t size) override;
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absl::Status Receive(void* buffer, size_t size, bool allow_partial_read,
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size_t* bytes_received) override;
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private:
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// Called by StartListening() for a specific IPV4 or IPV6 |addr_info|.
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// Passing 0 as port will bind to any available port.
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// Returns the port that was bound to.
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absl::StatusOr<int> StartListeningInternal(int port, addrinfo* addr);
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std::unique_ptr<struct ServerSocketInfo> socket_info_;
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};
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} // namespace cdc_ft
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#endif // CDC_RSYNC_SERVER_SERVER_SOCKET_H_
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