sock.h

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// Copyright (c) 2020-present 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/compat.h>
#include <util/time.h>
 
#include <cstdint>
#include <limits>
#include <memory>
#include <span>
#include <string>
#include <unordered_map>
 
class CThreadInterrupt;

inline constexpr auto MAX_WAIT_FOR_IO = 1s;
 
inline bool IOErrorIsPermanent(int err)
{
    return err != WSAEAGAIN && err != WSAEINTR && err != WSAEWOULDBLOCK && err != WSAEINPROGRESS;
}

class Sock
{
public:
    Sock() = delete;

    explicit Sock(SOCKET s);

    Sock(const Sock&) = delete;

    Sock(Sock&& other);

    virtual ~Sock();

    Sock& operator=(const Sock&) = delete;

    virtual Sock& operator=(Sock&& other);

    [[nodiscard]] virtual ssize_t Send(const void* data, size_t len, int flags) const;

    [[nodiscard]] virtual ssize_t Recv(void* buf, size_t len, int flags) const;

    [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const;

    [[nodiscard]] virtual int Bind(const sockaddr* addr, socklen_t addr_len) const;

    [[nodiscard]] virtual int Listen(int backlog) const;

    [[nodiscard]] virtual std::unique_ptr<Sock> Accept(sockaddr* addr, socklen_t* addr_len) const;

    [[nodiscard]] virtual int GetSockOpt(int level,
                                         int opt_name,
                                         void* opt_val,
                                         socklen_t* opt_len) const;

    [[nodiscard]] virtual int SetSockOpt(int level,
                                         int opt_name,
                                         const void* opt_val,
                                         socklen_t opt_len) const;

    [[nodiscard]] virtual int GetSockName(sockaddr* name, socklen_t* name_len) const;

    [[nodiscard]] virtual bool SetNonBlocking() const;

    [[nodiscard]] virtual bool IsSelectable() const;
 
    using Event = uint8_t;

    static constexpr Event RecvEvent = 0b001;

    static constexpr Event SendEvent = 0b010;

    static constexpr Event ErrorEvent = 0b100;

    [[nodiscard]] virtual bool Wait(std::chrono::milliseconds timeout,
                                    Event requested,
                                    Event* occurred = nullptr) const;

    struct Events {
        explicit Events(Event req) : requested{req} {}
        Event requested;
        Event occurred{0};
    };
 
    struct HashSharedPtrSock {
        size_t operator()(const std::shared_ptr<const Sock>& s) const
        {
            return s ? s->m_socket : std::numeric_limits<SOCKET>::max();
        }
    };
 
    struct EqualSharedPtrSock {
        bool operator()(const std::shared_ptr<const Sock>& lhs,
                        const std::shared_ptr<const Sock>& rhs) const
        {
            if (lhs && rhs) {
                return lhs->m_socket == rhs->m_socket;
            }
            if (!lhs && !rhs) {
                return true;
            }
            return false;
        }
    };

    using EventsPerSock = std::unordered_map<std::shared_ptr<const Sock>, Events, HashSharedPtrSock, EqualSharedPtrSock>;

    [[nodiscard]] virtual bool WaitMany(std::chrono::milliseconds timeout,
                                        EventsPerSock& events_per_sock) const;
 
    /* Higher level, convenience, methods. These may throw. */

    virtual void SendComplete(std::span<const unsigned char> data,
                              std::chrono::milliseconds timeout,
                              CThreadInterrupt& interrupt) const;

    virtual void SendComplete(std::span<const char> data,
                              std::chrono::milliseconds timeout,
                              CThreadInterrupt& interrupt) const;

    [[nodiscard]] virtual std::string RecvUntilTerminator(uint8_t terminator,
                                                          std::chrono::milliseconds timeout,
                                                          CThreadInterrupt& interrupt,
                                                          size_t max_data) const;

    [[nodiscard]] virtual bool IsConnected(std::string& errmsg) const;

    bool operator==(SOCKET s) const;
 
protected:
    SOCKET m_socket;
 
private:
    void Close();
};

std::string NetworkErrorString(int err);
 
#endif // BITCOIN_UTIL_SOCK_H