net/tcpclient.cc

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/* tcpclient.cc: Open a TCP connection to a server.
 *
 * Copyright 1999,2000,2001 BrightStation PLC
 * Copyright 2002 Ananova Ltd
 * Copyright 2004,2005,2006,2007,2008,2010 Olly Betts
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
 * USA
 */

#include <config.h>

#include "remoteconnection.h"
#include "tcpclient.h"
#include <xapian/error.h>

#include "safeerrno.h"
#include "safefcntl.h"
#include "safesysselect.h"
#include "socket_utils.h"

#include <cmath>
#include <cstring>
#ifndef __WIN32__
# include <netdb.h>
# include <netinet/in.h>
# include <netinet/tcp.h>
# include <sys/socket.h>
#endif

using namespace std;

int
TcpClient::open_socket(const std::string & hostname, int port,
                       double timeout_connect, bool tcp_nodelay)
{
    // FIXME: timeout on gethostbyname() ?
    struct hostent *host = gethostbyname(hostname.c_str());

    if (host == 0) {
        throw Xapian::NetworkError(std::string("Couldn't resolve host ") + hostname,
#ifdef __WIN32__
                socket_errno()
#else
                // "socket_errno()" is just errno on UNIX which is
                // inappropriate here - if gethostbyname() returns NULL an
                // error code is available in h_errno (with values
                // incompatible with errno).  On Linux at least, if h_errno
                // is < 0, then the error code *IS* in errno!
                (h_errno < 0 ? errno : -h_errno)
#endif
                );
    }

    int socketfd = socket(PF_INET, SOCK_STREAM, 0);
    if (socketfd < 0) {
        throw Xapian::NetworkError("Couldn't create socket", socket_errno());
    }

    struct sockaddr_in remaddr;
    memset(&remaddr, 0, sizeof(remaddr));
    remaddr.sin_family = AF_INET;
    remaddr.sin_port = htons(port);
    memcpy(&remaddr.sin_addr, host->h_addr, host->h_length);

#ifdef __WIN32__
    ULONG enabled = 1;
    int rc = ioctlsocket(socketfd, FIONBIO, &enabled);
#else
    int rc = fcntl(socketfd, F_SETFL, O_NDELAY);
#endif
    if (rc < 0) {
        int saved_errno = socket_errno(); // note down in case close hits an error
        close_fd_or_socket(socketfd);
        throw Xapian::NetworkError("Couldn't set O_NDELAY", saved_errno);
    }

    if (tcp_nodelay) {
        int optval = 1;
        // 4th argument might need to be void* or char* - cast it to char*
        // since C++ allows implicit conversion to void* but not from void*.
        if (setsockopt(socketfd, IPPROTO_TCP, TCP_NODELAY,
                       reinterpret_cast<char *>(&optval),
                       sizeof(optval)) < 0) {
            int saved_errno = socket_errno(); // note down in case close hits an error
            close_fd_or_socket(socketfd);
            throw Xapian::NetworkError("Couldn't set TCP_NODELAY", saved_errno);
        }
    }

    int retval = connect(socketfd, reinterpret_cast<sockaddr *>(&remaddr),
                         sizeof(remaddr));

    if (retval < 0) {
#ifdef __WIN32__
        if (WSAGetLastError() != WSAEWOULDBLOCK) {
#else
        if (socket_errno() != EINPROGRESS) {
#endif
            int saved_errno = socket_errno(); // note down in case close hits an error
            close_fd_or_socket(socketfd);
            throw Xapian::NetworkError("Couldn't connect (1)", saved_errno);
        }

        // wait for input to be available.
        fd_set fdset;
        FD_ZERO(&fdset);
        FD_SET(socketfd, &fdset);

        do {
            // FIXME: Reduce the timeout if we retry on EINTR.
            struct timeval tv;
            tv.tv_sec = long(timeout_connect);
            tv.tv_usec = long(std::fmod(timeout_connect, 1.0) * 1e6);

            retval = select(socketfd + 1, 0, &fdset, &fdset, &tv);
        } while (retval < 0 && errno == EINTR);

        if (retval < 0) {
            int saved_errno = errno;
            close_fd_or_socket(socketfd);
            throw Xapian::NetworkError("Couldn't connect (2)", saved_errno);
        }

        if (retval <= 0) {
            close_fd_or_socket(socketfd);
            throw Xapian::NetworkTimeoutError("Timed out waiting to connect", ETIMEDOUT);
        }

        int err = 0;
        SOCKLEN_T len = sizeof(err);

        // 4th argument might need to be void* or char* - cast it to char*
        // since C++ allows implicit conversion to void* but not from void*.
        retval = getsockopt(socketfd, SOL_SOCKET, SO_ERROR,
                            reinterpret_cast<char *>(&err), &len);

        if (retval < 0) {
            int saved_errno = socket_errno(); // note down in case close hits an error
            close_fd_or_socket(socketfd);
            throw Xapian::NetworkError("Couldn't get socket options", saved_errno);
        }
        if (err) {
            close_fd_or_socket(socketfd);
            throw Xapian::NetworkError("Couldn't connect (3)", err);
        }
    }

#ifdef __WIN32__
    enabled = 0;
    ioctlsocket(socketfd, FIONBIO, &enabled);
#else
    fcntl(socketfd, F_SETFL, 0);
#endif
    return socketfd;
}

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