path: root/libvncserver/sockets.c

/*
 * sockets.c - deal with TCP & UDP sockets.
 *
 * This code should be independent of any changes in the RFB protocol.  It just
 * deals with the X server scheduling stuff, calling rfbNewClientConnection and
 * rfbProcessClientMessage to actually deal with the protocol.  If a socket
 * needs to be closed for any reason then rfbCloseClient should be called, and
 * this in turn will call rfbClientConnectionGone.  To make an active
 * connection out, call rfbConnect - note that this does _not_ call
 * rfbNewClientConnection.
 *
 * This file is divided into two types of function.  Those beginning with
 * "rfb" are specific to sockets using the RFB protocol.  Those without the
 * "rfb" prefix are more general socket routines (which are used by the http
 * code).
 *
 * Thanks to Karl Hakimian for pointing out that some platforms return EAGAIN
 * not EWOULDBLOCK.
 */

/*
 *  Copyright (C) 2005 Rohit Kumar, Johannes E. Schindelin
 *  OSXvnc Copyright (C) 2001 Dan McGuirk <[email protected]>.
 *  Original Xvnc code Copyright (C) 1999 AT&T Laboratories Cambridge.  
 *  All Rights Reserved.
 *
 *  This 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 software 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 software; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,
 *  USA.
 */

#include <rfb/rfb.h>

#ifdef LIBVNCSERVER_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#ifdef LIBVNCSERVER_HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef LIBVNCSERVER_HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef LIBVNCSERVER_HAVE_NETINET_IN_H
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <netdb.h>
#include <arpa/inet.h>
#endif
#ifdef LIBVNCSERVER_HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
#include "rfbssl.h"
#endif

#if defined(__linux__) && defined(NEED_TIMEVAL)
struct timeval 
{
   long int tv_sec,tv_usec;
}
;
#endif

#ifdef LIBVNCSERVER_HAVE_FCNTL_H
#include <fcntl.h>
#endif

#include <errno.h>

#ifdef USE_LIBWRAP
#include <syslog.h>
#include <tcpd.h>
int allow_severity=LOG_INFO;
int deny_severity=LOG_WARNING;
#endif

#if defined(WIN32)
#ifndef __MINGW32__
#pragma warning (disable: 4018 4761)
#endif
#define read(sock,buf,len) recv(sock,buf,len,0)
#define EWOULDBLOCK WSAEWOULDBLOCK
#define ETIMEDOUT WSAETIMEDOUT
#define write(sock,buf,len) send(sock,buf,len,0)
#else
#define closesocket close
#endif

int rfbMaxClientWait = 20000;   /* time (ms) after which we decide client has
                                   gone away - needed to stop us hanging */

/*
 * rfbInitSockets sets up the TCP and UDP sockets to listen for RFB
 * connections.  It does nothing if called again.
 */

void
rfbInitSockets(rfbScreenInfoPtr rfbScreen)
{
    in_addr_t iface = rfbScreen->listenInterface;

    if (rfbScreen->socketState!=RFB_SOCKET_INIT)
	return;

    rfbScreen->socketState = RFB_SOCKET_READY;

    if (rfbScreen->inetdSock != -1) {
	const int one = 1;

        if(!rfbSetNonBlocking(rfbScreen->inetdSock))
	    return;

	if (setsockopt(rfbScreen->inetdSock, IPPROTO_TCP, TCP_NODELAY,
		       (char *)&one, sizeof(one)) < 0) {
	    rfbLogPerror("setsockopt");
	    return;
	}

    	FD_ZERO(&(rfbScreen->allFds));
    	FD_SET(rfbScreen->inetdSock, &(rfbScreen->allFds));
    	rfbScreen->maxFd = rfbScreen->inetdSock;
	return;
    }

    if(rfbScreen->autoPort) {
        int i;
        rfbLog("Autoprobing TCP port \n");
        for (i = 5900; i < 6000; i++) {
            if ((rfbScreen->listenSock = rfbListenOnTCPPort(i, iface)) >= 0) {
		rfbScreen->port = i;
		break;
	    }
        }

        if (i >= 6000) {
	    rfbLogPerror("Failure autoprobing");
	    return;
        }

        rfbLog("Autoprobing selected port %d\n", rfbScreen->port);
        FD_ZERO(&(rfbScreen->allFds));
        FD_SET(rfbScreen->listenSock, &(rfbScreen->allFds));
        rfbScreen->maxFd = rfbScreen->listenSock;
    }
    else if(rfbScreen->port>0) {
      rfbLog("Listening for VNC connections on TCP port %d\n", rfbScreen->port);

      if ((rfbScreen->listenSock = rfbListenOnTCPPort(rfbScreen->port, iface)) < 0) {
	rfbLogPerror("ListenOnTCPPort");
	return;
      }

      FD_ZERO(&(rfbScreen->allFds));
      FD_SET(rfbScreen->listenSock, &(rfbScreen->allFds));
      rfbScreen->maxFd = rfbScreen->listenSock;
    }

    if (rfbScreen->udpPort != 0) {
	rfbLog("rfbInitSockets: listening for input on UDP port %d\n",rfbScreen->udpPort);

	if ((rfbScreen->udpSock = rfbListenOnUDPPort(rfbScreen->udpPort, iface)) < 0) {
	    rfbLogPerror("ListenOnUDPPort");
	    return;
	}
	FD_SET(rfbScreen->udpSock, &(rfbScreen->allFds));
	rfbScreen->maxFd = max((int)rfbScreen->udpSock,rfbScreen->maxFd);
    }
}

void rfbShutdownSockets(rfbScreenInfoPtr rfbScreen)
{
    if (rfbScreen->socketState!=RFB_SOCKET_READY)
	return;

    rfbScreen->socketState = RFB_SOCKET_SHUTDOWN;

    if(rfbScreen->inetdSock>-1) {
	closesocket(rfbScreen->inetdSock);
	FD_CLR(rfbScreen->inetdSock,&rfbScreen->allFds);
	rfbScreen->inetdSock=-1;
    }

    if(rfbScreen->listenSock>-1) {
	closesocket(rfbScreen->listenSock);
	FD_CLR(rfbScreen->listenSock,&rfbScreen->allFds);
	rfbScreen->listenSock=-1;
    }

    if(rfbScreen->udpSock>-1) {
	closesocket(rfbScreen->udpSock);
	FD_CLR(rfbScreen->udpSock,&rfbScreen->allFds);
	rfbScreen->udpSock=-1;
    }
}

/*
 * rfbCheckFds is called from ProcessInputEvents to check for input on the RFB
 * socket(s).  If there is input to process, the appropriate function in the
 * RFB server code will be called (rfbNewClientConnection,
 * rfbProcessClientMessage, etc).
 */

int
rfbCheckFds(rfbScreenInfoPtr rfbScreen,long usec)
{
    int nfds;
    fd_set fds;
    struct timeval tv;
    struct sockaddr_in addr;
    socklen_t addrlen = sizeof(addr);
    char buf[6];
    rfbClientIteratorPtr i;
    rfbClientPtr cl;
    int result = 0;

    if (!rfbScreen->inetdInitDone && rfbScreen->inetdSock != -1) {
	rfbNewClientConnection(rfbScreen,rfbScreen->inetdSock); 
	rfbScreen->inetdInitDone = TRUE;
    }

    do {
	memcpy((char *)&fds, (char *)&(rfbScreen->allFds), sizeof(fd_set));
	tv.tv_sec = 0;
	tv.tv_usec = usec;
	nfds = select(rfbScreen->maxFd + 1, &fds, NULL, NULL /* &fds */, &tv);
	if (nfds == 0) {
	    /* timed out, check for async events */
            i = rfbGetClientIterator(rfbScreen);
            while((cl = rfbClientIteratorNext(i))) {
                if (cl->onHold)
                    continue;
                if (FD_ISSET(cl->sock, &(rfbScreen->allFds)))
                    rfbSendFileTransferChunk(cl);
            }
            rfbReleaseClientIterator(i);
	    return result;
	}

	if (nfds < 0) {
#ifdef WIN32
	    errno = WSAGetLastError();
#endif
	    if (errno != EINTR)
		rfbLogPerror("rfbCheckFds: select");
	    return -1;
	}

	result += nfds;

	if (rfbScreen->listenSock != -1 && FD_ISSET(rfbScreen->listenSock, &fds)) {

	    if (!rfbProcessNewConnection(rfbScreen))
                return -1;

	    FD_CLR(rfbScreen->listenSock, &fds);
	    if (--nfds == 0)
		return result;
	}

	if ((rfbScreen->udpSock != -1) && FD_ISSET(rfbScreen->udpSock, &fds)) {
	    if(!rfbScreen->udpClient)
		rfbNewUDPClient(rfbScreen);
	    if (recvfrom(rfbScreen->udpSock, buf, 1, MSG_PEEK,
			(struct sockaddr *)&addr, &addrlen) < 0) {
		rfbLogPerror("rfbCheckFds: UDP: recvfrom");
		rfbDisconnectUDPSock(rfbScreen);
		rfbScreen->udpSockConnected = FALSE;
	    } else {
		if (!rfbScreen->udpSockConnected ||
			(memcmp(&addr, &rfbScreen->udpRemoteAddr, addrlen) != 0))
		{
		    /* new remote end */
		    rfbLog("rfbCheckFds: UDP: got connection\n");

		    memcpy(&rfbScreen->udpRemoteAddr, &addr, addrlen);
		    rfbScreen->udpSockConnected = TRUE;

		    if (connect(rfbScreen->udpSock,
				(struct sockaddr *)&addr, addrlen) < 0) {
			rfbLogPerror("rfbCheckFds: UDP: connect");
			rfbDisconnectUDPSock(rfbScreen);
			return -1;
		    }

		    rfbNewUDPConnection(rfbScreen,rfbScreen->udpSock);
		}

		rfbProcessUDPInput(rfbScreen);
	    }

	    FD_CLR(rfbScreen->udpSock, &fds);
	    if (--nfds == 0)
		return result;
	}

	i = rfbGetClientIterator(rfbScreen);
	while((cl = rfbClientIteratorNext(i))) {

	    if (cl->onHold)
		continue;

            if (FD_ISSET(cl->sock, &(rfbScreen->allFds)))
            {
                if (FD_ISSET(cl->sock, &fds))
                    rfbProcessClientMessage(cl);
                else
                    rfbSendFileTransferChunk(cl);
            }
	}
	rfbReleaseClientIterator(i);
    } while(rfbScreen->handleEventsEagerly);
    return result;
}

rfbBool
rfbProcessNewConnection(rfbScreenInfoPtr rfbScreen)
{
    const int one = 1;
    int sock = -1;
    struct sockaddr_in addr;
    socklen_t addrlen = sizeof(addr);

    if ((sock = accept(rfbScreen->listenSock,
		       (struct sockaddr *)&addr, &addrlen)) < 0) {
      rfbLogPerror("rfbCheckFds: accept");
      return FALSE;
    }

    if(!rfbSetNonBlocking(sock)) {
      closesocket(sock);
      return FALSE;
    }

    if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
		   (char *)&one, sizeof(one)) < 0) {
      rfbLogPerror("rfbCheckFds: setsockopt");
      closesocket(sock);
      return FALSE;
    }

#ifdef USE_LIBWRAP
    if(!hosts_ctl("vnc",STRING_UNKNOWN,inet_ntoa(addr.sin_addr),
		  STRING_UNKNOWN)) {
      rfbLog("Rejected connection from client %s\n",
	     inet_ntoa(addr.sin_addr));
      closesocket(sock);
      return FALSE;
    }
#endif

    rfbLog("Got connection from client %s\n", inet_ntoa(addr.sin_addr));

    rfbNewClient(rfbScreen,sock);

    return TRUE;
}


void
rfbDisconnectUDPSock(rfbScreenInfoPtr rfbScreen)
{
  rfbScreen->udpSockConnected = FALSE;
}



void
rfbCloseClient(rfbClientPtr cl)
{
    rfbExtensionData* extension;

    for(extension=cl->extensions; extension; extension=extension->next)
	if(extension->extension->close)
	    extension->extension->close(cl, extension->data);

    LOCK(cl->updateMutex);
#ifdef LIBVNCSERVER_HAVE_LIBPTHREAD
    if (cl->sock != -1)
#endif
      {
	FD_CLR(cl->sock,&(cl->screen->allFds));
	if(cl->sock==cl->screen->maxFd)
	  while(cl->screen->maxFd>0
		&& !FD_ISSET(cl->screen->maxFd,&(cl->screen->allFds)))
	    cl->screen->maxFd--;
#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
	if (cl->sslctx)
	    rfbssl_destroy(cl);
	free(cl->wspath);
#endif
#ifndef __MINGW32__
	shutdown(cl->sock,SHUT_RDWR);
#endif
	closesocket(cl->sock);
	cl->sock = -1;
      }
    TSIGNAL(cl->updateCond);
    UNLOCK(cl->updateMutex);
}


/*
 * rfbConnect is called to make a connection out to a given TCP address.
 */

int
rfbConnect(rfbScreenInfoPtr rfbScreen,
           char *host,
           int port)
{
    int sock;
    int one = 1;

    rfbLog("Making connection to client on host %s port %d\n",
	   host,port);

    if ((sock = rfbConnectToTcpAddr(host, port)) < 0) {
	rfbLogPerror("connection failed");
	return -1;
    }

    if(!rfbSetNonBlocking(sock)) {
        closesocket(sock);
	return -1;
    }

    if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
		   (char *)&one, sizeof(one)) < 0) {
	rfbLogPerror("setsockopt failed");
	closesocket(sock);
	return -1;
    }

    /* AddEnabledDevice(sock); */
    FD_SET(sock, &rfbScreen->allFds);
    rfbScreen->maxFd = max(sock,rfbScreen->maxFd);

    return sock;
}

/*
 * ReadExact reads an exact number of bytes from a client.  Returns 1 if
 * those bytes have been read, 0 if the other end has closed, or -1 if an error
 * occurred (errno is set to ETIMEDOUT if it timed out).
 */

int
rfbReadExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)
{
    int sock = cl->sock;
    int n;
    fd_set fds;
    struct timeval tv;

    while (len > 0) {
#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
        if (cl->wsctx) {
            n = webSocketsDecode(cl, buf, len);
        } else if (cl->sslctx) {
	    n = rfbssl_read(cl, buf, len);
	} else {
            n = read(sock, buf, len);
        }
#else
        n = read(sock, buf, len);
#endif

        if (n > 0) {

            buf += n;
            len -= n;

        } else if (n == 0) {

            return 0;

        } else {
#ifdef WIN32
	    errno = WSAGetLastError();
#endif
	    if (errno == EINTR)
		continue;

#ifdef LIBVNCSERVER_ENOENT_WORKAROUND
	    if (errno != ENOENT)
#endif
            if (errno != EWOULDBLOCK && errno != EAGAIN) {
                return n;
            }

#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
	    if (cl->sslctx) {
		if (rfbssl_pending(cl))
		    continue;
	    }
#endif
            FD_ZERO(&fds);
            FD_SET(sock, &fds);
            tv.tv_sec = timeout / 1000;
            tv.tv_usec = (timeout % 1000) * 1000;
            n = select(sock+1, &fds, NULL, &fds, &tv);
            if (n < 0) {
                rfbLogPerror("ReadExact: select");
                return n;
            }
            if (n == 0) {
                rfbErr("ReadExact: select timeout\n");
                errno = ETIMEDOUT;
                return -1;
            }
        }
    }
#undef DEBUG_READ_EXACT
#ifdef DEBUG_READ_EXACT
    rfbLog("ReadExact %d bytes\n",len);
    for(n=0;n<len;n++)
	    fprintf(stderr,"%02x ",(unsigned char)buf[n]);
    fprintf(stderr,"\n");
#endif

    return 1;
}

int rfbReadExact(rfbClientPtr cl,char* buf,int len)
{
  /* favor the per-screen value if set */
  if(cl->screen && cl->screen->maxClientWait)
    return(rfbReadExactTimeout(cl,buf,len,cl->screen->maxClientWait));
  else
    return(rfbReadExactTimeout(cl,buf,len,rfbMaxClientWait));
}

/*
 * PeekExact peeks at an exact number of bytes from a client.  Returns 1 if
 * those bytes have been read, 0 if the other end has closed, or -1 if an
 * error occurred (errno is set to ETIMEDOUT if it timed out).
 */

int
rfbPeekExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)
{
    int sock = cl->sock;
    int n;
    fd_set fds;
    struct timeval tv;

    while (len > 0) {
#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
	if (cl->sslctx)
	    n = rfbssl_peek(cl, buf, len);
	else
#endif
	    n = recv(sock, buf, len, MSG_PEEK);

        if (n == len) {

            break;

        } else if (n == 0) {

            return 0;

        } else {
#ifdef WIN32
	    errno = WSAGetLastError();
#endif
	    if (errno == EINTR)
		continue;

#ifdef LIBVNCSERVER_ENOENT_WORKAROUND
	    if (errno != ENOENT)
#endif
            if (errno != EWOULDBLOCK && errno != EAGAIN) {
                return n;
            }

#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
	    if (cl->sslctx) {
		if (rfbssl_pending(cl))
		    continue;
	    }
#endif
            FD_ZERO(&fds);
            FD_SET(sock, &fds);
            tv.tv_sec = timeout / 1000;
            tv.tv_usec = (timeout % 1000) * 1000;
            n = select(sock+1, &fds, NULL, &fds, &tv);
            if (n < 0) {
                rfbLogPerror("PeekExact: select");
                return n;
            }
            if (n == 0) {
                errno = ETIMEDOUT;
                return -1;
            }
        }
    }
#undef DEBUG_READ_EXACT
#ifdef DEBUG_READ_EXACT
    rfbLog("PeekExact %d bytes\n",len);
    for(n=0;n<len;n++)
	    fprintf(stderr,"%02x ",(unsigned char)buf[n]);
    fprintf(stderr,"\n");
#endif

    return 1;
}

/*
 * WriteExact writes an exact number of bytes to a client.  Returns 1 if
 * those bytes have been written, or -1 if an error occurred (errno is set to
 * ETIMEDOUT if it timed out).
 */

int
rfbWriteExact(rfbClientPtr cl,
              const char *buf,
              int len)
{
    int sock = cl->sock;
    int n;
    fd_set fds;
    struct timeval tv;
    int totalTimeWaited = 0;
    const int timeout = (cl->screen && cl->screen->maxClientWait) ? cl->screen->maxClientWait : rfbMaxClientWait;

#undef DEBUG_WRITE_EXACT
#ifdef DEBUG_WRITE_EXACT
    rfbLog("WriteExact %d bytes\n",len);
    for(n=0;n<len;n++)
	    fprintf(stderr,"%02x ",(unsigned char)buf[n]);
    fprintf(stderr,"\n");
#endif

#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
    if (cl->wsctx) {
        char *tmp = NULL;
        if ((len = webSocketsEncode(cl, buf, len, &tmp)) < 0) {
            rfbErr("WriteExact: WebSockets encode error\n");
            return -1;
        }
        buf = tmp;
    }
#endif

    LOCK(cl->outputMutex);
    while (len > 0) {
#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
        if (cl->sslctx)
	    n = rfbssl_write(cl, buf, len);
	else
#endif
	    n = write(sock, buf, len);

        if (n > 0) {

            buf += n;
            len -= n;

        } else if (n == 0) {

            rfbErr("WriteExact: write returned 0?\n");
            return 0;

        } else {
#ifdef WIN32
			errno = WSAGetLastError();
#endif
	    if (errno == EINTR)
		continue;

            if (errno != EWOULDBLOCK && errno != EAGAIN) {
	        UNLOCK(cl->outputMutex);
                return n;
            }

            /* Retry every 5 seconds until we exceed timeout.  We
               need to do this because select doesn't necessarily return
               immediately when the other end has gone away */

            FD_ZERO(&fds);
            FD_SET(sock, &fds);
            tv.tv_sec = 5;
            tv.tv_usec = 0;
            n = select(sock+1, NULL, &fds, NULL /* &fds */, &tv);
	    if (n < 0) {
#ifdef WIN32
                errno=WSAGetLastError();
#endif
       	        if(errno==EINTR)
		    continue;
                rfbLogPerror("WriteExact: select");
                UNLOCK(cl->outputMutex);
                return n;
            }
            if (n == 0) {
                totalTimeWaited += 5000;
                if (totalTimeWaited >= timeout) {
                    errno = ETIMEDOUT;
                    UNLOCK(cl->outputMutex);
                    return -1;
                }
            } else {
                totalTimeWaited = 0;
            }
        }
    }
    UNLOCK(cl->outputMutex);
    return 1;
}

/* currently private, called by rfbProcessArguments() */
int
rfbStringToAddr(char *str, in_addr_t *addr)  {
    if (str == NULL || *str == '\0' || strcmp(str, "any") == 0) {
        *addr = htonl(INADDR_ANY);
    } else if (strcmp(str, "localhost") == 0) {
        *addr = htonl(INADDR_LOOPBACK);
    } else {
        struct hostent *hp;
        if ((*addr = inet_addr(str)) == htonl(INADDR_NONE)) {
            if (!(hp = gethostbyname(str))) {
                return 0;
            }
            *addr = *(unsigned long *)hp->h_addr;
        }
    }
    return 1;
}

int
rfbListenOnTCPPort(int port,
                   in_addr_t iface)
{
    struct sockaddr_in addr;
    int sock;
    int one = 1;

    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = iface;

    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
	return -1;
    }
    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
		   (char *)&one, sizeof(one)) < 0) {
	closesocket(sock);
	return -1;
    }
    if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
	closesocket(sock);
	return -1;
    }
    if (listen(sock, 32) < 0) {
	closesocket(sock);
	return -1;
    }

    return sock;
}

int
rfbConnectToTcpAddr(char *host,
                    int port)
{
    struct hostent *hp;
    int sock;
    struct sockaddr_in addr;

    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);

    if ((addr.sin_addr.s_addr = inet_addr(host)) == htonl(INADDR_NONE))
    {
	if (!(hp = gethostbyname(host))) {
	    errno = EINVAL;
	    return -1;
	}
	addr.sin_addr.s_addr = *(unsigned long *)hp->h_addr;
    }

    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
	return -1;
    }

    if (connect(sock, (struct sockaddr *)&addr, (sizeof(addr))) < 0) {
	closesocket(sock);
	return -1;
    }

    return sock;
}

int
rfbListenOnUDPPort(int port,
                   in_addr_t iface)
{
    struct sockaddr_in addr;
    int sock;
    int one = 1;

    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = iface;

    if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
	return -1;
    }
    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
		   (char *)&one, sizeof(one)) < 0) {
	return -1;
    }
    if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
	return -1;
    }

    return sock;
}

/*
 * rfbSetNonBlocking sets a socket into non-blocking mode.
 */
rfbBool
rfbSetNonBlocking(int sock)
{
#ifdef WIN32
  unsigned long block=1;
  if(ioctlsocket(sock, FIONBIO, &block) == SOCKET_ERROR) {
    errno=WSAGetLastError();
#else
  int flags = fcntl(sock, F_GETFL);
  if(flags < 0 || fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) {
#endif
    rfbLogPerror("Setting socket to non-blocking failed");
    return FALSE;
  }
  return TRUE;
}