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libtdevnc/libvncserver/websockets.c

449 lines
13 KiB

/*
* websockets.c - deal with WebSockets clients.
*
* This code should be independent of any changes in the RFB protocol. It is
* an additional handshake and framing of normal sockets:
* http://www.whatwg.org/specs/web-socket-protocol/
*
*/
/*
* Copyright (C) 2010 Joel Martin
*
* 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>
#include <resolv.h> /* __b64_ntop */
/* errno */
#include <errno.h>
#include <md5.h>
#define FLASH_POLICY_RESPONSE "<cross-domain-policy><allow-access-from domain=\"*\" to-ports=\"*\" /></cross-domain-policy>\n"
#define SZ_FLASH_POLICY_RESPONSE 93
#define WEBSOCKETS_HANDSHAKE_RESPONSE "HTTP/1.1 101 Web Socket Protocol Handshake\r\n\
Upgrade: WebSocket\r\n\
Connection: Upgrade\r\n\
%sWebSocket-Origin: %s\r\n\
%sWebSocket-Location: %s://%s%s\r\n\
%sWebSocket-Protocol: sample\r\n\
\r\n%s"
#define WEBSOCKETS_CLIENT_CONNECT_WAIT_MS 100
#define WEBSOCKETS_CLIENT_SEND_WAIT_MS 20
#define WEBSOCKETS_MAX_HANDSHAKE_LEN 4096
#if defined(__linux__) && defined(NEED_TIMEVAL)
struct timeval
{
long int tv_sec,tv_usec;
}
;
#endif
static rfbBool webSocketsHandshake(rfbClientPtr cl, char *scheme);
void webSocketsGenMd5(char * target, char *key1, char *key2, char *key3);
static int
min (int a, int b) {
return a < b ? a : b;
}
/*
* rfbWebSocketsHandshake is called to handle new WebSockets connections
*/
rfbBool
webSocketsCheck (rfbClientPtr cl)
{
char bbuf[4], *scheme;
int ret;
ret = rfbPeekExactTimeout(cl, bbuf, 4,
WEBSOCKETS_CLIENT_CONNECT_WAIT_MS);
if ((ret < 0) && (errno == ETIMEDOUT)) {
rfbLog("Normal socket connection\n");
return TRUE;
} else if (ret <= 0) {
rfbErr("webSocketsHandshake: unknown connection error\n");
return FALSE;
}
if (strncmp(bbuf, "<", 1) == 0) {
rfbLog("Got Flash policy request, sending response\n");
if (rfbWriteExact(cl, FLASH_POLICY_RESPONSE,
SZ_FLASH_POLICY_RESPONSE) < 0) {
rfbErr("webSocketsHandshake: failed sending Flash policy response");
}
return FALSE;
} else if (strncmp(bbuf, "\x16", 1) == 0) {
cl->webSocketsSSL = TRUE;
rfbLog("Got TLS/SSL WebSockets connection\n");
scheme = "wss";
/* TODO */
/* bbuf = ... */
return FALSE;
} else {
cl->webSocketsSSL = FALSE;
scheme = "ws";
}
if (strncmp(bbuf, "GET ", 4) != 0) {
rfbErr("webSocketsHandshake: invalid client header\n");
return FALSE;
}
rfbLog("Got '%s' WebSockets handshake\n", scheme);
if (!webSocketsHandshake(cl, scheme)) {
return FALSE;
}
cl->webSockets = TRUE; /* Start WebSockets framing */
return TRUE;
}
static rfbBool
webSocketsHandshake(rfbClientPtr cl, char *scheme)
{
char *buf, *response, *line;
int n, linestart = 0, len = 0, llen;
char prefix[5], trailer[17];
char *path, *host, *origin;
char *key1 = NULL, *key2 = NULL, *key3 = NULL;
buf = (char *) malloc(WEBSOCKETS_MAX_HANDSHAKE_LEN);
if (!buf) {
rfbLogPerror("webSocketsHandshake: malloc");
return FALSE;
}
response = (char *) malloc(WEBSOCKETS_MAX_HANDSHAKE_LEN);
if (!response) {
free(buf);
rfbLogPerror("webSocketsHandshake: malloc");
return FALSE;
}
while (len < WEBSOCKETS_MAX_HANDSHAKE_LEN-1) {
if ((n = rfbReadExactTimeout(cl, buf+len, 1,
WEBSOCKETS_CLIENT_SEND_WAIT_MS)) <= 0) {
if ((n < 0) && (errno == ETIMEDOUT)) {
break;
}
if (n == 0)
rfbLog("webSocketsHandshake: client gone\n");
else
rfbLogPerror("webSocketsHandshake: read");
return FALSE;
}
len += 1;
llen = len - linestart;
if (((llen >= 2)) && (buf[len-1] == '\n')) {
line = buf+linestart;
if ((llen == 2) && ((strncmp("\r\n\r\n", buf+len-4, 4)) == 0)) {
if (key1 && key2) {
if ((n = rfbReadExact(cl, buf+len, 8)) <= 0) {
if ((n < 0) && (errno == ETIMEDOUT)) {
break;
}
if (n == 0)
rfbLog("webSocketsHandshake: client gone\n");
else
rfbLogPerror("webSocketsHandshake: read");
return FALSE;
}
rfbLog("Got key3\n");
key3 = buf+len;
len += 8;
} else {
buf[len] = '\0';
}
break;
} else if ((llen >= 16) && ((strncmp("GET ", line, min(llen,4))) == 0)) {
/* 16 = 4 ("GET ") + 1 ("/.*") + 11 (" HTTP/1.1\r\n") */
/* rfbLog("Got path\n"); */
path = line+4;
buf[len-11] = '\0'; /* Trim trailing " HTTP/1.1\r\n" */
if (strstr(path, "b64encode")) {
rfbLog(" - using base64 encoding\n");
cl->webSocketsBase64 = TRUE;
} else {
rfbLog(" - using UTF-8 encoding\n");
cl->webSocketsBase64 = FALSE;
}
} else if ((strncmp("Host: ", line, min(llen,6))) == 0) {
/* rfbLog("Got host\n"); */
host = line+6;
buf[len-2] = '\0';
} else if ((strncmp("Origin: ", line, min(llen,8))) == 0) {
/* rfbLog("Got origin\n"); */
origin = line+8;
buf[len-2] = '\0';
} else if ((strncmp("Sec-Websocket-Key1: ", line, min(llen,20))) == 0) {
/* rfbLog("Got key1\n"); */
key1 = line+20;
buf[len-2] = '\0';
} else if ((strncmp("Sec-Websocket-Key2: ", line, min(llen,20))) == 0) {
/* rfbLog("Got key2\n"); */
key2 = line+20;
buf[len-2] = '\0';
}
linestart = len;
}
}
if (!(path && host && origin)) {
rfbErr("webSocketsHandshake: incomplete client handshake\n");
free(response);
free(buf);
return FALSE;
}
/*
* Generate the WebSockets server response based on the the headers sent
* by the client.
*/
if (!(key1 && key2 && key3)) {
rfbLog(" - WebSockets client version 75\n");
prefix[0] = '\0';
trailer[0] = '\0';
} else {
rfbLog(" - WebSockets client version 76\n");
snprintf(prefix, 5, "Sec-");
webSocketsGenMd5(trailer, key1, key2, key3);
}
snprintf(response, WEBSOCKETS_MAX_HANDSHAKE_LEN,
WEBSOCKETS_HANDSHAKE_RESPONSE, prefix, origin, prefix, scheme,
host, path, prefix, trailer);
if (rfbWriteExact(cl, response, strlen(response)) < 0) {
rfbErr("webSocketsHandshake: failed sending WebSockets response\n");
free(response);
free(buf);
return FALSE;
}
/* rfbLog("webSocketsHandshake: handshake complete\n"); */
return TRUE;
}
void
webSocketsGenMd5(char * target, char *key1, char *key2, char *key3)
{
unsigned int i, spaces1 = 0, spaces2 = 0;
unsigned long num1 = 0, num2 = 0;
unsigned char buf[17];
for (i=0; i < strlen(key1); i++) {
if (key1[i] == ' ') {
spaces1 += 1;
}
if ((key1[i] >= 48) && (key1[i] <= 57)) {
num1 = num1 * 10 + (key1[i] - 48);
}
}
num1 = num1 / spaces1;
for (i=0; i < strlen(key2); i++) {
if (key2[i] == ' ') {
spaces2 += 1;
}
if ((key2[i] >= 48) && (key2[i] <= 57)) {
num2 = num2 * 10 + (key2[i] - 48);
}
}
num2 = num2 / spaces2;
/* Pack it big-endian */
buf[0] = (num1 & 0xff000000) >> 24;
buf[1] = (num1 & 0xff0000) >> 16;
buf[2] = (num1 & 0xff00) >> 8;
buf[3] = num1 & 0xff;
buf[4] = (num2 & 0xff000000) >> 24;
buf[5] = (num2 & 0xff0000) >> 16;
buf[6] = (num2 & 0xff00) >> 8;
buf[7] = num2 & 0xff;
strncpy((char *)buf+8, key3, 8);
buf[16] = '\0';
md5_buffer((char *)buf, 16, target);
target[16] = '\0';
return;
}
int
webSocketsEncode(rfbClientPtr cl, const char *src, int len)
{
int i, sz = 0;
unsigned char chr;
cl->encodeBuf[sz++] = '\x00';
if (cl->webSocketsBase64) {
len = __b64_ntop((unsigned char *)src, len, cl->encodeBuf+sz, UPDATE_BUF_SIZE*2);
if (len < 0) {
return len;
}
sz += len;
} else {
for (i=0; i < len; i++) {
chr = src[i];
if (chr < 128) {
if (chr == 0x00) {
cl->encodeBuf[sz++] = '\xc4';
cl->encodeBuf[sz++] = '\x80';
} else {
cl->encodeBuf[sz++] = chr;
}
} else {
if (chr < 192) {
cl->encodeBuf[sz++] = '\xc2';
cl->encodeBuf[sz++] = chr;
} else {
cl->encodeBuf[sz++] = '\xc3';
cl->encodeBuf[sz++] = chr - 64;
}
}
}
}
cl->encodeBuf[sz++] = '\xff';
/* rfbLog("<< webSocketsEncode: %d\n", len); */
return sz;
}
int
webSocketsDecode(rfbClientPtr cl, char *dst, int len)
{
int retlen = 0, n, i, avail, modlen, needlen;
char *buf, *end = NULL;
unsigned char chr;
buf = cl->decodeBuf;
n = recv(cl->sock, buf, len*2+2, MSG_PEEK);
if (n <= 0) {
rfbLog("recv of %d\n", n);
return n;
}
if (buf[0] == '\xff') {
i = read(cl->sock, buf, 1); /* Consume marker */
buf++;
n--;
}
if (buf[0] == '\x00') {
i = read(cl->sock, buf, 1); /* Consume marker */
buf++;
n--;
}
/* rfbLog(">> webSocketsDecode, len: %d, n: %d\n", len, n); */
end = memchr(buf, '\xff', len*2+2);
if (!end) {
end = buf + n;
}
avail = end - buf;
if (cl->webSocketsBase64) {
/* Base64 encoded WebSockets stream */
len -= cl->carrylen;
/* Determine how much base64 data we need */
modlen = len + (len+2)/3;
needlen = modlen;
if (needlen % 4) {
needlen += 4 - (needlen % 4);
}
if (needlen > avail) {
/* rfbLog("Waiting for more base64 data\n"); */
errno = EAGAIN;
return -1;
}
/* Any carryover from previous decode */
for (i=0; i < cl->carrylen; i++) {
/* rfbLog("Adding carryover %d\n", cl->carryBuf[i]); */
dst[i] = cl->carryBuf[i];
retlen += 1;
}
/* Decode the rest of what we need */
buf[needlen] = '\x00'; /* Replace end marker with end of string */
/* rfbLog("buf: %s\n", buf); */
n = __b64_pton(buf, (unsigned char *)dst+retlen, 2+len);
if (n < len) {
rfbErr("Base64 decode error\n");
errno = EIO;
return -1;
}
retlen += n;
/* Consume the data from socket */
/* rfbLog("here1, needlen: %d, n: %d, len: %d\n", needlen, n, len); */
i = read(cl->sock, buf, needlen);
cl->carrylen = n - len;
retlen -= cl->carrylen;
for (i=0; i < cl->carrylen; i++) {
/* rfbLog("Saving carryover %d\n", dst[retlen + i]); */
cl->carryBuf[i] = dst[retlen + i];
}
} else {
/* UTF-8 encoded WebSockets stream */
while (retlen < len) {
chr = *buf;
buf += 1;
if (chr < 128) {
dst[retlen++] = chr;
} else {
if (buf >= end) {
rfbErr("Not enough UTF-8 data to decode\n");
errno = EIO;
return -1;
}
chr = *buf;
buf += 1;
switch (chr) {
case (unsigned char) '\xc2':
dst[retlen++] = chr;
break;
case (unsigned char) '\xc3':
dst[retlen++] = chr + 64;
break;
case (unsigned char) '\xc4':
dst[retlen++] = 0;
break;
}
}
}
}
#if 0
sprintf(debug, "dst:");
for (i = 0; i < retlen; i++) {
sprintf(debug+strlen(debug), "%d,", dst[i]);
}
rfbLog("%s\n", debug);
rfbLog("<< webSocketsDecode, retlen: %d\n", retlen);
#endif
return retlen;
}