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// Copyright (c) 2020-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_UTIL_SOCK_H
#define BITCOIN_UTIL_SOCK_H
#include <compat.h>
#include <threadinterrupt.h>
#include <util/time.h>
#include <chrono>
#include <string>
/**
* Maximum time to wait for I/O readiness.
* It will take up until this time to break off in case of an interruption.
*/
static constexpr auto MAX_WAIT_FOR_IO = 1s;
/**
* RAII helper class that manages a socket. Mimics `std::unique_ptr`, but instead of a pointer it
* contains a socket and closes it automatically when it goes out of scope.
*/
class Sock
{
public:
/**
* Default constructor, creates an empty object that does nothing when destroyed.
*/
Sock();
/**
* Take ownership of an existent socket.
*/
explicit Sock(SOCKET s);
/**
* Copy constructor, disabled because closing the same socket twice is undesirable.
*/
Sock(const Sock&) = delete;
/**
* Move constructor, grab the socket from another object and close ours (if set).
*/
Sock(Sock&& other);
/**
* Destructor, close the socket or do nothing if empty.
*/
virtual ~Sock();
/**
* Copy assignment operator, disabled because closing the same socket twice is undesirable.
*/
Sock& operator=(const Sock&) = delete;
/**
* Move assignment operator, grab the socket from another object and close ours (if set).
*/
virtual Sock& operator=(Sock&& other);
/**
* Get the value of the contained socket.
* @return socket or INVALID_SOCKET if empty
*/
virtual SOCKET Get() const;
/**
* Get the value of the contained socket and drop ownership. It will not be closed by the
* destructor after this call.
* @return socket or INVALID_SOCKET if empty
*/
virtual SOCKET Release();
/**
* Close if non-empty.
*/
virtual void Reset();
/**
* send(2) wrapper. Equivalent to `send(this->Get(), data, len, flags);`. Code that uses this
* wrapper can be unit-tested if this method is overridden by a mock Sock implementation.
*/
virtual ssize_t Send(const void* data, size_t len, int flags) const;
/**
* recv(2) wrapper. Equivalent to `recv(this->Get(), buf, len, flags);`. Code that uses this
* wrapper can be unit-tested if this method is overridden by a mock Sock implementation.
*/
virtual ssize_t Recv(void* buf, size_t len, int flags) const;
using Event = uint8_t;
/**
* If passed to `Wait()`, then it will wait for readiness to read from the socket.
*/
static constexpr Event RECV = 0b01;
/**
* If passed to `Wait()`, then it will wait for readiness to send to the socket.
*/
static constexpr Event SEND = 0b10;
/**
* Wait for readiness for input (recv) or output (send).
* @param[in] timeout Wait this much for at least one of the requested events to occur.
* @param[in] requested Wait for those events, bitwise-or of `RECV` and `SEND`.
* @param[out] occurred If not nullptr and `true` is returned, then upon return this
* indicates which of the requested events occurred. A timeout is indicated by return
* value of `true` and `occurred` being set to 0.
* @return true on success and false otherwise
*/
virtual bool Wait(std::chrono::milliseconds timeout,
Event requested,
Event* occurred = nullptr) const;
/* Higher level, convenience, methods. These may throw. */
/**
* Send the given data, retrying on transient errors.
* @param[in] data Data to send.
* @param[in] timeout Timeout for the entire operation.
* @param[in] interrupt If this is signaled then the operation is canceled.
* @throws std::runtime_error if the operation cannot be completed. In this case only some of
* the data will be written to the socket.
*/
virtual void SendComplete(const std::string& data,
std::chrono::milliseconds timeout,
CThreadInterrupt& interrupt) const;
/**
* Read from socket until a terminator character is encountered. Will never consume bytes past
* the terminator from the socket.
* @param[in] terminator Character up to which to read from the socket.
* @param[in] timeout Timeout for the entire operation.
* @param[in] interrupt If this is signaled then the operation is canceled.
* @param[in] max_data The maximum amount of data (in bytes) to receive. If this many bytes
* are received and there is still no terminator, then this method will throw an exception.
* @return The data that has been read, without the terminating character.
* @throws std::runtime_error if the operation cannot be completed. In this case some bytes may
* have been consumed from the socket.
*/
virtual std::string RecvUntilTerminator(uint8_t terminator,
std::chrono::milliseconds timeout,
CThreadInterrupt& interrupt,
size_t max_data) const;
/**
* Check if still connected.
* @param[out] err The error string, if the socket has been disconnected.
* @return true if connected
*/
virtual bool IsConnected(std::string& errmsg) const;
private:
/**
* Contained socket. `INVALID_SOCKET` designates the object is empty.
*/
SOCKET m_socket;
};
/** Return readable error string for a network error code */
std::string NetworkErrorString(int err);
/** Close socket and set hSocket to INVALID_SOCKET */
bool CloseSocket(SOCKET& hSocket);
#endif // BITCOIN_UTIL_SOCK_H
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