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486 lines
14 KiB
486 lines
14 KiB
/*
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* websockets.c - deal with WebSockets clients.
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*
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* This code should be independent of any changes in the RFB protocol. It is
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* an additional handshake and framing of normal sockets:
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* http://www.whatwg.org/specs/web-socket-protocol/
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*
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*/
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/*
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* Copyright (C) 2010 Joel Martin
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*
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* This is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This software is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this software; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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* USA.
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*/
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#include <rfb/rfb.h>
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#include <resolv.h> /* __b64_ntop */
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/* errno */
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#include <errno.h>
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#include <md5.h>
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#define FLASH_POLICY_RESPONSE "<cross-domain-policy><allow-access-from domain=\"*\" to-ports=\"*\" /></cross-domain-policy>\n"
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#define SZ_FLASH_POLICY_RESPONSE 93
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#define WEBSOCKETS_HANDSHAKE_RESPONSE "HTTP/1.1 101 Web Socket Protocol Handshake\r\n\
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Upgrade: WebSocket\r\n\
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Connection: Upgrade\r\n\
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%sWebSocket-Origin: %s\r\n\
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%sWebSocket-Location: %s://%s%s\r\n\
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%sWebSocket-Protocol: %s\r\n\
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\r\n%s"
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#define WEBSOCKETS_CLIENT_CONNECT_WAIT_MS 100
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#define WEBSOCKETS_CLIENT_SEND_WAIT_MS 100
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#define WEBSOCKETS_MAX_HANDSHAKE_LEN 4096
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#if defined(__linux__) && defined(NEED_TIMEVAL)
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struct timeval
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{
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long int tv_sec,tv_usec;
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}
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;
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#endif
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static rfbBool webSocketsHandshake(rfbClientPtr cl, char *scheme);
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void webSocketsGenMd5(char * target, char *key1, char *key2, char *key3);
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static int
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min (int a, int b) {
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return a < b ? a : b;
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}
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/*
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* rfbWebSocketsHandshake is called to handle new WebSockets connections
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*/
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rfbBool
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webSocketsCheck (rfbClientPtr cl)
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{
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char bbuf[4], *scheme;
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int ret;
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ret = rfbPeekExactTimeout(cl, bbuf, 4,
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WEBSOCKETS_CLIENT_CONNECT_WAIT_MS);
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if ((ret < 0) && (errno == ETIMEDOUT)) {
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rfbLog("Normal socket connection\n");
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return TRUE;
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} else if (ret <= 0) {
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rfbErr("webSocketsHandshake: unknown connection error\n");
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return FALSE;
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}
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if (strncmp(bbuf, "<", 1) == 0) {
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rfbLog("Got Flash policy request, sending response\n");
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if (rfbWriteExact(cl, FLASH_POLICY_RESPONSE,
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SZ_FLASH_POLICY_RESPONSE) < 0) {
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rfbErr("webSocketsHandshake: failed sending Flash policy response");
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}
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return FALSE;
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} else if (strncmp(bbuf, "\x16", 1) == 0) {
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cl->webSocketsSSL = TRUE;
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rfbLog("Got TLS/SSL WebSockets connection\n");
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scheme = "wss";
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/* TODO */
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/* bbuf = ... */
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return FALSE;
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} else {
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cl->webSocketsSSL = FALSE;
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scheme = "ws";
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}
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if (strncmp(bbuf, "GET ", 4) != 0) {
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rfbErr("webSocketsHandshake: invalid client header\n");
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return FALSE;
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}
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rfbLog("Got '%s' WebSockets handshake\n", scheme);
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if (!webSocketsHandshake(cl, scheme)) {
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return FALSE;
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}
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cl->webSockets = TRUE; /* Start WebSockets framing */
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return TRUE;
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}
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static rfbBool
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webSocketsHandshake(rfbClientPtr cl, char *scheme)
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{
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char *buf, *response, *line;
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int n, linestart = 0, len = 0, llen;
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char prefix[5], trailer[17];
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char *path = NULL, *host = NULL, *origin = NULL, *protocol = NULL;
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char *key1 = NULL, *key2 = NULL, *key3 = NULL;
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buf = (char *) malloc(WEBSOCKETS_MAX_HANDSHAKE_LEN);
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if (!buf) {
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rfbLogPerror("webSocketsHandshake: malloc");
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return FALSE;
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}
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response = (char *) malloc(WEBSOCKETS_MAX_HANDSHAKE_LEN);
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if (!response) {
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free(buf);
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rfbLogPerror("webSocketsHandshake: malloc");
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return FALSE;
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}
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while (len < WEBSOCKETS_MAX_HANDSHAKE_LEN-1) {
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if ((n = rfbReadExactTimeout(cl, buf+len, 1,
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WEBSOCKETS_CLIENT_SEND_WAIT_MS)) <= 0) {
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if ((n < 0) && (errno == ETIMEDOUT)) {
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break;
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}
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if (n == 0)
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rfbLog("webSocketsHandshake: client gone\n");
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else
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rfbLogPerror("webSocketsHandshake: read");
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return FALSE;
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}
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len += 1;
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llen = len - linestart;
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if (((llen >= 2)) && (buf[len-1] == '\n')) {
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line = buf+linestart;
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if ((llen == 2) && (strncmp("\r\n", line, 2) == 0)) {
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if (key1 && key2) {
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if ((n = rfbReadExact(cl, buf+len, 8)) <= 0) {
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if ((n < 0) && (errno == ETIMEDOUT)) {
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break;
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}
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if (n == 0)
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rfbLog("webSocketsHandshake: client gone\n");
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else
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rfbLogPerror("webSocketsHandshake: read");
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return FALSE;
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}
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rfbLog("Got key3\n");
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key3 = buf+len;
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len += 8;
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} else {
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buf[len] = '\0';
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}
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break;
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} else if ((llen >= 16) && ((strncmp("GET ", line, min(llen,4))) == 0)) {
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/* 16 = 4 ("GET ") + 1 ("/.*") + 11 (" HTTP/1.1\r\n") */
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path = line+4;
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buf[len-11] = '\0'; /* Trim trailing " HTTP/1.1\r\n" */
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cl->webSocketsBase64 = TRUE;
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/* rfbLog("Got path: %s\n", path); */
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} else if ((strncasecmp("host: ", line, min(llen,6))) == 0) {
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host = line+6;
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buf[len-2] = '\0';
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/* rfbLog("Got host: %s\n", host); */
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} else if ((strncasecmp("origin: ", line, min(llen,8))) == 0) {
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origin = line+8;
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buf[len-2] = '\0';
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/* rfbLog("Got origin: %s\n", origin); */
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} else if ((strncasecmp("sec-websocket-key1: ", line, min(llen,20))) == 0) {
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key1 = line+20;
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buf[len-2] = '\0';
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/* rfbLog("Got key1: %s\n", key1); */
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} else if ((strncasecmp("sec-websocket-key2: ", line, min(llen,20))) == 0) {
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key2 = line+20;
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buf[len-2] = '\0';
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/* rfbLog("Got key2: %s\n", key2); */
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} else if ((strncasecmp("sec-websocket-protocol: ", line, min(llen,24))) == 0) {
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protocol = line+24;
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buf[len-2] = '\0';
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/* rfbLog("Got protocol: %s\n", protocol); */
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}
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linestart = len;
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}
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}
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if (!(path && host && origin)) {
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rfbErr("webSocketsHandshake: incomplete client handshake\n");
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free(response);
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free(buf);
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return FALSE;
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}
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/*
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if ((!protocol) || (!strcasestr(protocol, "base64"))) {
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rfbErr("webSocketsHandshake: base64 subprotocol not supported by client\n");
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free(response);
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free(buf);
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return FALSE;
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}
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*/
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/*
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* Generate the WebSockets server response based on the the headers sent
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* by the client.
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*/
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if (!(key1 && key2 && key3)) {
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rfbLog(" - WebSockets client version 75\n");
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prefix[0] = '\0';
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trailer[0] = '\0';
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} else {
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rfbLog(" - WebSockets client version 76\n");
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snprintf(prefix, 5, "Sec-");
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webSocketsGenMd5(trailer, key1, key2, key3);
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}
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snprintf(response, WEBSOCKETS_MAX_HANDSHAKE_LEN,
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WEBSOCKETS_HANDSHAKE_RESPONSE, prefix, origin, prefix, scheme,
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host, path, prefix, protocol, trailer);
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if (rfbWriteExact(cl, response, strlen(response)) < 0) {
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rfbErr("webSocketsHandshake: failed sending WebSockets response\n");
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free(response);
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free(buf);
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return FALSE;
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}
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/* rfbLog("webSocketsHandshake: handshake complete\n"); */
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return TRUE;
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}
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void
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webSocketsGenMd5(char * target, char *key1, char *key2, char *key3)
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{
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unsigned int i, spaces1 = 0, spaces2 = 0;
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unsigned long num1 = 0, num2 = 0;
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unsigned char buf[17];
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for (i=0; i < strlen(key1); i++) {
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if (key1[i] == ' ') {
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spaces1 += 1;
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}
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if ((key1[i] >= 48) && (key1[i] <= 57)) {
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num1 = num1 * 10 + (key1[i] - 48);
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}
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}
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num1 = num1 / spaces1;
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for (i=0; i < strlen(key2); i++) {
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if (key2[i] == ' ') {
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spaces2 += 1;
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}
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if ((key2[i] >= 48) && (key2[i] <= 57)) {
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num2 = num2 * 10 + (key2[i] - 48);
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}
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}
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num2 = num2 / spaces2;
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/* Pack it big-endian */
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buf[0] = (num1 & 0xff000000) >> 24;
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buf[1] = (num1 & 0xff0000) >> 16;
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buf[2] = (num1 & 0xff00) >> 8;
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buf[3] = num1 & 0xff;
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buf[4] = (num2 & 0xff000000) >> 24;
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buf[5] = (num2 & 0xff0000) >> 16;
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buf[6] = (num2 & 0xff00) >> 8;
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buf[7] = num2 & 0xff;
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strncpy((char *)buf+8, key3, 8);
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buf[16] = '\0';
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md5_buffer((char *)buf, 16, target);
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target[16] = '\0';
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return;
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}
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int
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webSocketsEncode(rfbClientPtr cl, const char *src, int len)
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{
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int i, sz = 0;
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unsigned char chr;
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cl->encodeBuf[sz++] = '\x00';
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if (cl->webSocketsBase64) {
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len = __b64_ntop((unsigned char *)src, len, cl->encodeBuf+sz, UPDATE_BUF_SIZE*2);
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if (len < 0) {
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return len;
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}
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sz += len;
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} else {
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for (i=0; i < len; i++) {
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chr = src[i];
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if (chr < 128) {
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if (chr == 0x00) {
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cl->encodeBuf[sz++] = '\xc4';
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cl->encodeBuf[sz++] = '\x80';
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} else {
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cl->encodeBuf[sz++] = chr;
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}
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} else {
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if (chr < 192) {
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cl->encodeBuf[sz++] = '\xc2';
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cl->encodeBuf[sz++] = chr;
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} else {
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cl->encodeBuf[sz++] = '\xc3';
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cl->encodeBuf[sz++] = chr - 64;
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}
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}
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}
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}
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cl->encodeBuf[sz++] = '\xff';
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/* rfbLog("<< webSocketsEncode: %d\n", len); */
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return sz;
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}
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int
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webSocketsDecode(rfbClientPtr cl, char *dst, int len)
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{
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int retlen = 0, n, i, avail, modlen, needlen, actual;
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char *buf, *end = NULL;
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unsigned char chr, chr2;
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buf = cl->decodeBuf;
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n = recv(cl->sock, buf, len*2+2, MSG_PEEK);
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if (n <= 0) {
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rfbLog("recv of %d\n", n);
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return n;
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}
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if (cl->webSocketsBase64) {
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/* Base64 encoded WebSockets stream */
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if (buf[0] == '\xff') {
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i = read(cl->sock, buf, 1); /* Consume marker */
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buf++;
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n--;
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}
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if (n == 0) {
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errno = EAGAIN;
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return -1;
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}
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if (buf[0] == '\x00') {
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i = read(cl->sock, buf, 1); /* Consume marker */
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buf++;
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n--;
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}
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if (n == 0) {
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errno = EAGAIN;
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return -1;
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}
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/* end = memchr(buf, '\xff', len*2+2); */
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end = memchr(buf, '\xff', n);
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if (!end) {
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end = buf + n;
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}
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avail = end - buf;
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len -= cl->carrylen;
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/* Determine how much base64 data we need */
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modlen = len + (len+2)/3;
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needlen = modlen;
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if (needlen % 4) {
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needlen += 4 - (needlen % 4);
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}
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if (needlen > avail) {
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/* rfbLog("Waiting for more base64 data\n"); */
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errno = EAGAIN;
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return -1;
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}
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/* Any carryover from previous decode */
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for (i=0; i < cl->carrylen; i++) {
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/* rfbLog("Adding carryover %d\n", cl->carryBuf[i]); */
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dst[i] = cl->carryBuf[i];
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retlen += 1;
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}
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/* Decode the rest of what we need */
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buf[needlen] = '\x00'; /* Replace end marker with end of string */
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/* rfbLog("buf: %s\n", buf); */
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n = __b64_pton(buf, (unsigned char *)dst+retlen, 2+len);
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if (n < len) {
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rfbErr("Base64 decode error\n");
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errno = EIO;
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return -1;
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}
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retlen += n;
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/* Consume the data from socket */
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i = read(cl->sock, buf, needlen);
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cl->carrylen = n - len;
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retlen -= cl->carrylen;
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for (i=0; i < cl->carrylen; i++) {
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/* rfbLog("Saving carryover %d\n", dst[retlen + i]); */
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cl->carryBuf[i] = dst[retlen + i];
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}
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} else {
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/* UTF-8 encoded WebSockets stream */
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actual = 0;
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for (needlen = 0; needlen < n && actual < len; needlen++) {
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chr = buf[needlen];
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if ((chr > 0) && (chr < 128)) {
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actual++;
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} else if ((chr > 127) && (chr < 255)) {
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if (needlen + 1 >= n) {
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break;
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}
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needlen++;
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actual++;
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}
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}
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if (actual < len) {
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errno = EAGAIN;
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return -1;
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}
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/* Consume what we need */
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if ((n = read(cl->sock, buf, needlen)) < needlen) {
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return n;
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}
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while (retlen < len) {
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chr = buf[0];
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buf += 1;
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if (chr == 0) {
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/* Begin frame marker, just skip it */
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} else if (chr == 255) {
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/* Begin frame marker, just skip it */
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} else if (chr < 128) {
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dst[retlen++] = chr;
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} else {
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chr2 = buf[0];
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buf += 1;
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switch (chr) {
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case (unsigned char) '\xc2':
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dst[retlen++] = chr2;
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break;
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case (unsigned char) '\xc3':
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dst[retlen++] = chr2 + 64;
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break;
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case (unsigned char) '\xc4':
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dst[retlen++] = 0;
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break;
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default:
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rfbErr("Invalid UTF-8 encoding\n");
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errno = EIO;
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return -1;
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}
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}
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}
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}
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/* rfbLog("<< webSocketsDecode, retlen: %d\n", retlen); */
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return retlen;
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}
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