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sockets.c

/*
 *  Copyright (C) 1997, 1998 Olivetti & Oracle Research Laboratory
 *
 *  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.
 */

/*
 * sockets.c - functions to deal with sockets.
 */

#include <unistd.h>
#include <sys/socket.h>
#include <errno.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <x2vnc.h>

void PrintInHex(char *buf, int len);

Bool errorMessageFromReadExact = True;
Bool useSSHTunnel;
char *useSSHGateway;

/*
 * Read an exact number of bytes, and don't return until you've got them.
 */

Bool
ReadExact(int sock, char *buf, int n)
{
    int i = 0;
    int j;

    while (i < n) {
      j = read(sock, buf + i, (n - i));
      if (j <= 0) {
          if (j < 0) {
            fprintf(stderr,programName);
            perror(": read");
          } else {
            if (errorMessageFromReadExact) {
                fprintf(stderr,"%s: read failed\n",programName);
            }
          }
          return False;
      }
      i += j;
    }
    if (debug)
      PrintInHex(buf,n);
    return True;
}


/*
 * Write an exact number of bytes, and don't return until you've sent them.
 */

Bool
WriteExact(int sock, char *buf, int n)
{
    int i = 0;
    int j;

    while (i < n) {
      j = write(sock, buf + i, (n - i));
      if (j <= 0) {
          if (j < 0) {
            fprintf(stderr,programName);
            perror(": write");
          } else {
            fprintf(stderr,"%s: write failed\n",programName);
          }
          return False;
      }
      i += j;
    }
    return True;
}


/*
 * ConnectToTcpAddr connects to the given TCP port.
 */

int
ConnectToTcpAddr(unsigned int host, int port)
{
  int sock;
  struct sockaddr_in addr;
  int one = 1;
  
  addr.sin_family = AF_INET;
  addr.sin_port = htons(port);
  addr.sin_addr.s_addr = host;
  
  if(useSSHTunnel)
  {
    char *remote, *gateway;
    if(useSSHGateway)
    {
      gateway=useSSHGateway;
      remote=inet_ntoa(addr.sin_addr);
    }else{
      gateway=inet_ntoa(addr.sin_addr);
      remote="127.0.0.1";
    }
    addr.sin_port=htons(tunnel(gateway, remote, port));
    inet_aton("127.0.0.1",& addr.sin_addr);
  }
  
  sock = socket(AF_INET, SOCK_STREAM, 0);
  if (sock < 0) {
    fprintf(stderr,programName);
    perror(": ConnectToTcpAddr: socket");
    return -1;
  }
  
  if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
    fprintf(stderr,programName);
    perror(": ConnectToTcpAddr: connect");
    close(sock);
    return -1;
  }
  
  if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (char *)&one, sizeof(one)) < 0) {
    fprintf(stderr,programName);
    perror(": ConnectToTcpAddr: setsockopt");
    close(sock);
    return -1;
  }
  
  return sock;
}



/*
 * ListenAtTcpPort starts listening at the given TCP port.
 */

int
ListenAtTcpPort(int port)
{
    int sock;
    struct sockaddr_in addr;
    int one = 1;

    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;

    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock < 0) {
      fprintf(stderr,programName);
      perror(": ListenAtTcpPort: socket");
      return -1;
    }

    if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
               (const char *)&one, sizeof(one)) < 0) {
      fprintf(stderr,programName);
      perror(": ListenAtTcpPort: setsockopt");
      close(sock);
      return -1;
    }

    if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
      fprintf(stderr,programName);
      perror(": ListenAtTcpPort: bind");
      close(sock);
      return -1;
    }

    if (listen(sock, 5) < 0) {
      fprintf(stderr,programName);
      perror(": ListenAtTcpPort: listen");
      close(sock);
      return -1;
    }

    return sock;
}

int getFreePort(void)
{
  int sock=-1;
  struct sockaddr_in addr;
  int one = 1;
  int x;
  static int last;

  for(x=0;x<100;x++)
  {
    int port = 5500 + last % 100;
    last+=4711;
  
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;
    
    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock < 0 ||
        setsockopt(sock, SOL_SOCKET, SO_REUSEADDR,
                   (const char *)&one, sizeof(one)) < 0 ||
        bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) 
    {
      close(sock);
    }else{
      close(sock);
      return port;
    }
  }
  return -1;
}


/*
 * AcceptTcpConnection accepts a TCP connection.
 */

int
AcceptTcpConnection(int listenSock)
{
    int sock;
    struct sockaddr_in addr;
    int addrlen = sizeof(addr);
    int one = 1;

    sock = accept(listenSock, (struct sockaddr *) &addr, &addrlen);
    if (sock < 0) {
      fprintf(stderr,programName);
      perror(": AcceptTcpConnection: accept");
      return -1;
    }

    if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY,
               (char *)&one, sizeof(one)) < 0) {
      fprintf(stderr,programName);
      perror(": AcceptTcpConnection: setsockopt");
      close(sock);
      return -1;
    }

    return sock;
}


/*
 * StringToIPAddr - convert a host string to an IP address.
 */

int
StringToIPAddr(const char *str, unsigned int *addr)
{
    struct hostent *hp;

    if ((*addr = inet_addr(str)) == -1)
    {
      if (!(hp = gethostbyname(str)))
          return 0;

      *addr = *(unsigned int *)hp->h_addr;
    }

    return 1;
}


/*
 * Test if the other end of a socket is on the same machine.
 */

Bool
SameMachine(int sock)
{
    struct sockaddr_in peeraddr, myaddr;
    int addrlen = sizeof(struct sockaddr_in);

    getpeername(sock, (struct sockaddr *)&peeraddr, &addrlen);
    getsockname(sock, (struct sockaddr *)&myaddr, &addrlen);

    return (peeraddr.sin_addr.s_addr == myaddr.sin_addr.s_addr);
}


/*
 * Print out the contents of a packet for debugging.
 */

void
PrintInHex(char *buf, int len)
{
    int i, j;
    char c, str[17];

    str[16] = 0;

    fprintf(stderr,"ReadExact: ");

    for (i = 0; i < len; i++)
    {
      if ((i % 16 == 0) && (i != 0)) {
          fprintf(stderr,"           ");
      }
      c = buf[i];
      str[i % 16] = (((c > 31) && (c < 127)) ? c : '.');
      fprintf(stderr,"%02x ",(unsigned char)c);
      if ((i % 4) == 3)
          fprintf(stderr," ");
      if ((i % 16) == 15)
      {
          fprintf(stderr,"%s\n",str);
      }
    }
    if ((i % 16) != 0)
    {
      for (j = i % 16; j < 16; j++)
      {
          fprintf(stderr,"   ");
          if ((j % 4) == 3) fprintf(stderr," ");
      }
      str[i % 16] = 0;
      fprintf(stderr,"%s\n",str);
    }

    fflush(stderr);
}


int tunnel(char *gatewayhost, char *remotehost, int remoteport)
{
  char *space, *cmd;
  int port=getFreePort();

  space=malloc( (gatewayhost ? strlen(gatewayhost) : strlen(remotehost)) + strlen(remotehost) + 1024);
  if(!space)
  {
    fprintf(stderr,"Failed to malloc environment buffer!\n");
    exit(1);
  }

  sprintf(space,"LOCALPORT=%d",port);
  putenv(space);
  space+=strlen(space)+1;

  sprintf(space,"REMOTEHOST=%s",remotehost);
  putenv(space);
  space+=strlen(space)+1;
  
  sprintf(space,"GATEWAYHOST=%s",gatewayhost ? gatewayhost : remotehost);
  putenv(space);
  space+=strlen(space)+1;
  
  sprintf(space,"REMOTEPORT=%d",remoteport);
  putenv(space);
  space+=strlen(space)+1;

  cmd=getenv("X2VNC_SSH_CMD");
  /* Using -X tells ssh to turn off the NAGLE algorithm, which is required for any form of speed */
  if(!cmd) cmd="ssh -A -X -f -L \"$LOCALPORT:$REMOTEHOST:$REMOTEPORT\" \"$GATEWAYHOST\" 'ssh-add;sleep 60'";

  if(system(cmd) < 0)
  {
    perror("tunnel:system");
    exit(1);
  }
  return port;
}

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