sockets.c

/*
 *  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.
 */

/*
 * 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 <fcntl.h>
#include <assert.h>
#include <rfb/rfbclient.h>

void PrintInHex(char *buf, int len);

rfbBool errorMessageOnReadFailure = TRUE;

#define BUF_SIZE 8192
static char buf[BUF_SIZE];
static char *bufoutptr = buf;
static int buffered = 0;

/*
 * ReadFromRFBServer is called whenever we want to read some data from the RFB
 * server.  It is non-trivial for two reasons:
 *
 * 1. For efficiency it performs some intelligent buffering, avoiding invoking
 *    the read() system call too often.  For small chunks of data, it simply
 *    copies the data out of an internal buffer.  For large amounts of data it
 *    reads directly into the buffer provided by the caller.
 *
 * 2. Whenever read() would block, it invokes the Xt event dispatching
 *    mechanism to process X events.  In fact, this is the only place these
 *    events are processed, as there is no XtAppMainLoop in the program.
 */

rfbBool
ReadFromRFBServer(rfbClient* client, char *out, unsigned int n)
{
  if (n <= buffered) {
    memcpy(out, bufoutptr, n);
    bufoutptr += n;
    buffered -= n;
    return TRUE;
  }

  memcpy(out, bufoutptr, buffered);

  out += buffered;
  n -= buffered;

  bufoutptr = buf;
  buffered = 0;

  if (n <= BUF_SIZE) {

    while (buffered < n) {
      int i = read(client->sock, buf + buffered, BUF_SIZE - buffered);
      if (i <= 0) {
	if (i < 0) {
	  if (errno == EWOULDBLOCK || errno == EAGAIN) {
	    /* TODO:
	       ProcessXtEvents();
	    */
	    i = 0;
	  } else {
	    perror("read");
	    return FALSE;
	  }
	} else {
	  if (errorMessageOnReadFailure) {
	    rfbClientLog("VNC server closed connection\n");
	  }
	  return FALSE;
	}
      }
      buffered += i;
    }

    memcpy(out, bufoutptr, n);
    bufoutptr += n;
    buffered -= n;
    return TRUE;

  } else {

    while (n > 0) {
      int i = read(client->sock, out, n);
      if (i <= 0) {
	if (i < 0) {
	  if (errno == EWOULDBLOCK || errno == EAGAIN) {
	    /* TODO:
	       ProcessXtEvents();
	    */
	    i = 0;
	  } else {
	    perror("read");
	    return FALSE;
	  }
	} else {
	  if (errorMessageOnReadFailure) {
	    rfbClientLog("VNC server closed connection\n");
	  }
	  return FALSE;
	}
      }
      out += i;
      n -= i;
    }

    return TRUE;
  }
}


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

rfbBool
WriteToRFBServer(rfbClient* client, char *buf, int n)
{
  fd_set fds;
  int i = 0;
  int j;

  while (i < n) {
    j = write(client->sock, buf + i, (n - i));
    if (j <= 0) {
      if (j < 0) {
	if (errno == EWOULDBLOCK || errno == EAGAIN) {
	  FD_ZERO(&fds);
	  FD_SET(client->sock,&fds);

	  if (select(client->sock+1, NULL, &fds, NULL, NULL) <= 0) {
	    perror("select");
	    return FALSE;
	  }
	  j = 0;
	} else {
	  perror("write");
	  return FALSE;
	}
      } else {
	rfbClientLog("write failed\n");
	return FALSE;
      }
    }
    i += j;
  }
  return TRUE;
}


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

int
ConnectClientToTcpAddr(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;

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

  if (connect(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
    perror("ConnectToTcpAddr: connect");
    close(sock);
    return -1;
  }

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

  return sock;
}



/*
 * FindFreeTcpPort tries to find unused TCP port in the range
 * (TUNNEL_PORT_OFFSET, TUNNEL_PORT_OFFSET + 99]. Returns 0 on failure.
 */

int
FindFreeTcpPort(void)
{
  int sock, port;
  struct sockaddr_in addr;

  addr.sin_family = AF_INET;
  addr.sin_addr.s_addr = INADDR_ANY;

  sock = socket(AF_INET, SOCK_STREAM, 0);
  if (sock < 0) {
    perror(": FindFreeTcpPort: socket");
    return 0;
  }

  for (port = TUNNEL_PORT_OFFSET + 99; port > TUNNEL_PORT_OFFSET; port--) {
    addr.sin_port = htons((unsigned short)port);
    if (bind(sock, (struct sockaddr *)&addr, sizeof(addr)) == 0) {
      close(sock);
      return port;
    }
  }

  close(sock);
  return 0;
}


/*
 * 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) {
    perror("ListenAtTcpPort: socket");
    return -1;
  }

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

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

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

  return sock;
}


/*
 * 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) {
    perror("AcceptTcpConnection: accept");
    return -1;
  }

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

  return sock;
}


/*
 * SetNonBlocking sets a socket into non-blocking mode.
 */

rfbBool
SetNonBlocking(int sock)
{
  if (fcntl(sock, F_SETFL, O_NONBLOCK) < 0) {
    perror("AcceptTcpConnection: fcntl");
    return FALSE;
  }
  return TRUE;
}


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

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

  if (strcmp(str,"") == 0) {
    *addr = 0; /* local */
    return TRUE;
  }

  *addr = inet_addr(str);

  if (*addr != -1)
    return TRUE;

  hp = gethostbyname(str);

  if (hp) {
    *addr = *(unsigned int *)hp->h_addr;
    return TRUE;
  }

  return FALSE;
}


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

rfbBool
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;

  rfbClientLog("ReadExact: ");

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

  fflush(stderr);
}