libzmq/src/tcp.cpp

/*
    Copyright (c) 2007-2014 Contributors as noted in the AUTHORS file

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    0MQ is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "ip.hpp"
#include "tcp.hpp"
#include "err.hpp"
#include "platform.hpp"

#if defined ZMQ_HAVE_WINDOWS
#include "windows.hpp"
#else
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#endif

#if defined ZMQ_HAVE_OPENVMS
#include <ioctl.h>
#endif

void zmq::tune_tcp_socket (fd_t s_)
{
    //  Disable Nagle's algorithm. We are doing data batching on 0MQ level,
    //  so using Nagle wouldn't improve throughput in anyway, but it would
    //  hurt latency.
    int nodelay = 1;
    int rc = setsockopt (s_, IPPROTO_TCP, TCP_NODELAY, (char*) &nodelay,
        sizeof (int));
#ifdef ZMQ_HAVE_WINDOWS
    wsa_assert (rc != SOCKET_ERROR);
#else
    errno_assert (rc == 0);
#endif

#ifdef ZMQ_HAVE_OPENVMS
    //  Disable delayed acknowledgements as they hurt latency is serious manner.
    int nodelack = 1;
    rc = setsockopt (s_, IPPROTO_TCP, TCP_NODELACK, (char*) &nodelack,
        sizeof (int));
    errno_assert (rc != SOCKET_ERROR);
#endif
}

void zmq::set_tcp_send_buffer (fd_t sockfd_, int bufsize_)
{
    const int rc = setsockopt (sockfd_, SOL_SOCKET, SO_SNDBUF,
        (char*) &bufsize_, sizeof bufsize_);
#ifdef ZMQ_HAVE_WINDOWS
    wsa_assert (rc != SOCKET_ERROR);
#else
    errno_assert (rc == 0);
#endif
}

void zmq::set_tcp_receive_buffer (fd_t sockfd_, int bufsize_)
{
    const int rc = setsockopt (sockfd_, SOL_SOCKET, SO_RCVBUF,
        (char*) &bufsize_, sizeof bufsize_);
#ifdef ZMQ_HAVE_WINDOWS
    wsa_assert (rc != SOCKET_ERROR);
#else
    errno_assert (rc == 0);
#endif
}

void zmq::tune_tcp_keepalives (fd_t s_, int keepalive_, int keepalive_cnt_, int keepalive_idle_, int keepalive_intvl_)
{
    // These options are used only under certain #ifdefs below.
    (void)keepalive_;
    (void)keepalive_cnt_;
    (void)keepalive_idle_;
    (void)keepalive_intvl_;

    // If none of the #ifdefs apply, then s_ is unused.
    (void)s_;

    //  Tuning TCP keep-alives if platform allows it
    //  All values = -1 means skip and leave it for OS
#ifdef ZMQ_HAVE_WINDOWS
    if (keepalive_ != -1) {
        tcp_keepalive keepalive_opts;
        keepalive_opts.onoff = keepalive_;
        keepalive_opts.keepalivetime = keepalive_idle_ != -1 ? keepalive_idle_ * 1000 : 7200000;
        keepalive_opts.keepaliveinterval = keepalive_intvl_ != -1 ? keepalive_intvl_ * 1000 : 1000;
        DWORD num_bytes_returned;
        int rc = WSAIoctl(s_, SIO_KEEPALIVE_VALS, &keepalive_opts, sizeof(keepalive_opts), NULL, 0, &num_bytes_returned, NULL, NULL);
        wsa_assert (rc != SOCKET_ERROR);
    }
#else
#ifdef ZMQ_HAVE_SO_KEEPALIVE
    if (keepalive_ != -1) {
        int rc = setsockopt (s_, SOL_SOCKET, SO_KEEPALIVE, (char*) &keepalive_, sizeof (int));
        errno_assert (rc == 0);

#ifdef ZMQ_HAVE_TCP_KEEPCNT
        if (keepalive_cnt_ != -1) {
            int rc = setsockopt (s_, IPPROTO_TCP, TCP_KEEPCNT, &keepalive_cnt_, sizeof (int));
            errno_assert (rc == 0);
        }
#endif // ZMQ_HAVE_TCP_KEEPCNT

#ifdef ZMQ_HAVE_TCP_KEEPIDLE
        if (keepalive_idle_ != -1) {
            int rc = setsockopt (s_, IPPROTO_TCP, TCP_KEEPIDLE, &keepalive_idle_, sizeof (int));
            errno_assert (rc == 0);
        }
#else // ZMQ_HAVE_TCP_KEEPIDLE
#ifdef ZMQ_HAVE_TCP_KEEPALIVE
        if (keepalive_idle_ != -1) {
            int rc = setsockopt (s_, IPPROTO_TCP, TCP_KEEPALIVE, &keepalive_idle_, sizeof (int));
            errno_assert (rc == 0);
        }
#endif // ZMQ_HAVE_TCP_KEEPALIVE
#endif // ZMQ_HAVE_TCP_KEEPIDLE

#ifdef ZMQ_HAVE_TCP_KEEPINTVL
        if (keepalive_intvl_ != -1) {
            int rc = setsockopt (s_, IPPROTO_TCP, TCP_KEEPINTVL, &keepalive_intvl_, sizeof (int));
            errno_assert (rc == 0);
        }
#endif // ZMQ_HAVE_TCP_KEEPINTVL
    }
#endif // ZMQ_HAVE_SO_KEEPALIVE
#endif // ZMQ_HAVE_WINDOWS
}

int zmq::tcp_write (fd_t s_, const void *data_, size_t size_)
{
#ifdef ZMQ_HAVE_WINDOWS

    int nbytes = send (s_, (char*) data_, (int) size_, 0);

    //  If not a single byte can be written to the socket in non-blocking mode
    //  we'll get an error (this may happen during the speculative write).
    if (nbytes == SOCKET_ERROR && WSAGetLastError () == WSAEWOULDBLOCK)
        return 0;

    //  Signalise peer failure.
    if (nbytes == SOCKET_ERROR && (
          WSAGetLastError () == WSAENETDOWN ||
          WSAGetLastError () == WSAENETRESET ||
          WSAGetLastError () == WSAEHOSTUNREACH ||
          WSAGetLastError () == WSAECONNABORTED ||
          WSAGetLastError () == WSAETIMEDOUT ||
          WSAGetLastError () == WSAECONNRESET))
        return -1;

    wsa_assert (nbytes != SOCKET_ERROR);
    return nbytes;

#else
    ssize_t nbytes = send (s_, data_, size_, 0);

    //  Several errors are OK. When speculative write is being done we may not
    //  be able to write a single byte from the socket. Also, SIGSTOP issued
    //  by a debugging tool can result in EINTR error.
    if (nbytes == -1 && (errno == EAGAIN || errno == EWOULDBLOCK ||
          errno == EINTR))
        return 0;

    //  Signalise peer failure.
    if (nbytes == -1) {
        errno_assert (errno != EACCES
                   && errno != EBADF
                   && errno != EDESTADDRREQ
                   && errno != EFAULT
                   && errno != EINVAL
                   && errno != EISCONN
                   && errno != EMSGSIZE
                   && errno != ENOMEM
                   && errno != ENOTSOCK
                   && errno != EOPNOTSUPP);
        return -1;
    }

    return static_cast <int> (nbytes);

#endif
}

int zmq::tcp_read (fd_t s_, void *data_, size_t size_)
{
#ifdef ZMQ_HAVE_WINDOWS

    const int rc = recv (s_, (char*) data_, (int) size_, 0);

    //  If not a single byte can be read from the socket in non-blocking mode
    //  we'll get an error (this may happen during the speculative read).
    if (rc == SOCKET_ERROR) {
        if (WSAGetLastError () == WSAEWOULDBLOCK)
            errno = EAGAIN;
        else {
            wsa_assert (WSAGetLastError () == WSAENETDOWN
                     || WSAGetLastError () == WSAENETRESET
                     || WSAGetLastError () == WSAECONNABORTED
                     || WSAGetLastError () == WSAETIMEDOUT
                     || WSAGetLastError () == WSAECONNRESET
                     || WSAGetLastError () == WSAECONNREFUSED
                     || WSAGetLastError () == WSAENOTCONN);
            errno = wsa_error_to_errno (WSAGetLastError ());
        }
    }

    return rc == SOCKET_ERROR? -1: rc;

#else

    const ssize_t rc = recv (s_, data_, size_, 0);

    //  Several errors are OK. When speculative read is being done we may not
    //  be able to read a single byte from the socket. Also, SIGSTOP issued
    //  by a debugging tool can result in EINTR error.
    if (rc == -1) {
        errno_assert (errno != EBADF
                   && errno != EFAULT
                   && errno != EINVAL
                   && errno != ENOMEM
                   && errno != ENOTSOCK);
        if (errno == EWOULDBLOCK || errno == EINTR)
            errno = EAGAIN;
    }

    return static_cast <int> (rc);

#endif
}