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repeaterproc.c
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repeaterproc.c
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/*
* Copyright (C) 2002 Ultr@VNC Team Members. All Rights Reserved.
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
* USA.
*
* Program is based on the
* http://www.imasy.or.jp/~gotoh/ssh/connect.c
* Written By Shun-ichi GOTO <[email protected]>
*
* If the source code for the program is not available from the place
* from which you received this file, check
* http://ultravnc.sourceforge.net/
*
* Linux port (C) 2005- Jari Korhonen, [email protected]
* Ansification 2012- Gernot Tenchio, https://github.com/tenchman
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
#include "commondefines.h"
#include "repeater.h"
#define LOCAL_SOCKET 1
#ifndef FD_ALLOC
#define FD_ALLOC(nfds) ((fd_set*) malloc((nfds+7) / 8 ) )
#endif
/* Return values:
* 1: Error (in select)
* 2: Server has disconnected
* 3: Viewer has disconnected
* 4: Error when reading from viewer
* 5: Error when reading from server
*/
int doRepeater(int server, int viewer)
{
/** vars for viewer input data **/
char viewerBuf[1024]; /* viewer input buffer */
int viewerBufLen; /* available data in viewerBuf */
/** vars for server input data **/
char serverBuf[1024]; /* server input buffer */
int serverBufLen; /* available data in serverBuf */
/** other variables **/
int nfds, len;
fd_set ifds;
fd_set ofds;
/*
* repeater between server and viewer
*/
nfds = ((viewer < server) ? server : viewer) + 1;
viewerBufLen = 0;
serverBufLen = 0;
while (true) {
FD_ZERO(&ifds);
FD_ZERO(&ofds);
/** prepare for reading viewer input **/
if ((viewerBufLen < (int) sizeof(viewerBuf))) {
FD_SET(viewer, &ifds);
}
/** prepare for reading server input **/
if ((serverBufLen < (int) sizeof(serverBuf))) {
FD_SET(server, &ifds);
}
if (select(nfds, &ifds, &ofds, NULL, NULL) == -1) {
/* EINTR is normal if user presses ctrl+c */
if (errno != EINTR) {
/*
* error in select, parent process should close both connections
*/
debug(LEVEL_2, "doRepeater(): select() failed, errno=%d (%s)\n", errno, strerror(errno));
}
return 1;
}
/*
* server => viewer
*/
if (FD_ISSET(server, &ifds)
&& (serverBufLen < (int) sizeof(serverBuf))) {
len = recv(server, serverBuf + serverBufLen, sizeof(serverBuf) - serverBufLen, 0);
if (len == 0) {
debug(LEVEL_3, "doRepeater(): connection closed by server\n");
/* When server closes connection, parent process should also disconnect viewer */
return 2;
}
else if (len == -1) {
if (errno != ECONNRESET) {
/*
* error
*/
debug(LEVEL_2, "doRepeater(): recv() from server failed, errno=%d (%s)\n", errno, strerror(errno));
return 5;
}
else {
debug(LEVEL_2, "doRepeater(): ECONNRESET detected\n");
}
}
else {
serverBufLen += len;
}
}
/*
* viewer => server
*/
if (FD_ISSET(viewer, &ifds)
&& (viewerBufLen < (int) sizeof(viewerBuf))) {
len = recv(viewer, viewerBuf + viewerBufLen, sizeof(viewerBuf) - viewerBufLen, 0);
if (len == 0) {
debug(LEVEL_3, "doRepeater(): connection closed by viewer\n");
/* When viewer closes connection,parent process should also disconnect server */
return 3;
}
else if (len == -1) {
/*
* error on reading from viewer
*/
debug(LEVEL_2, "doRepeater(): recv() from viewer failed, errno = %d (%s)\n", errno, strerror(errno));
return 4;
}
else {
/*
* repeat
*/
viewerBufLen += len;
}
}
/*
* flush data in viewerbuffer to server
*/
if (0 < viewerBufLen) {
len = send(server, viewerBuf, viewerBufLen, 0);
if (len == -1) {
debug(LEVEL_2, "doRepeater(): send() (to server) failed, errno=%d (%s)\n", errno, strerror(errno));
}
else if (0 < len) {
/*
* move data on to top of buffer
*/
viewerBufLen -= len;
if (0 < viewerBufLen)
memcpy(viewerBuf, viewerBuf + len, viewerBufLen);
assert(0 <= viewerBufLen);
}
}
/*
* flush data in serverbuffer to viewer
*/
if (0 < serverBufLen) {
len = send(viewer, serverBuf, serverBufLen, 0);
if (len == -1) {
debug(LEVEL_2, "doRepeater(): send() (to viewer) failed, errno=%d (%s)\n", errno, strerror(errno));
}
else {
serverBufLen -= len;
if (len < serverBufLen)
memcpy(serverBuf, serverBuf + len, serverBufLen);
assert(0 <= serverBufLen);
}
}
}
return 0; /* to make gcc happy */
}