/*
* libwebsockets - small server side websockets and web server implementation
*
* Copyright (C) 2010 Andy Green <andy@warmcat.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation:
* version 2.1 of the License.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301 USA
*/
#include "private-libwebsockets.h"
static int
interpret_key(const char *key, unsigned long *result)
{
char digits[20];
int digit_pos = 0;
const char *p = key;
unsigned int spaces = 0;
unsigned long acc = 0;
int rem = 0;
while (*p) {
if (isdigit(*p)) {
if (digit_pos == sizeof(digits) - 1)
return -1;
digits[digit_pos++] = *p;
}
p++;
}
digits[digit_pos] = '\0';
if (!digit_pos)
return -2;
while (*key) {
if (*key == ' ')
spaces++;
key++;
}
if (!spaces)
return -3;
p = &digits[0];
while (*p) {
rem = (rem * 10) + ((*p++) - '0');
acc = (acc * 10) + (rem / spaces);
rem -= (rem / spaces) * spaces;
}
if (rem) {
fprintf(stderr, "nonzero handshake remainder\n");
return -1;
}
*result = acc;
return 0;
}
static int
handshake_00(struct libwebsocket *wsi)
{
unsigned long key1, key2;
unsigned char sum[16];
char *response;
char *p;
int n;
/* Confirm we have all the necessary pieces */
if (!wsi->utf8_token[WSI_TOKEN_ORIGIN].token_len ||
!wsi->utf8_token[WSI_TOKEN_HOST].token_len ||
!wsi->utf8_token[WSI_TOKEN_CHALLENGE].token_len ||
!wsi->utf8_token[WSI_TOKEN_KEY1].token_len ||
!wsi->utf8_token[WSI_TOKEN_KEY2].token_len)
/* completed header processing, but missing some bits */
goto bail;
/* allocate the per-connection user memory (if any) */
if (wsi->protocol->per_session_data_size) {
wsi->user_space = malloc(
wsi->protocol->per_session_data_size);
if (wsi->user_space == NULL) {
fprintf(stderr, "Out of memory for "
"conn user space\n");
goto bail;
}
} else
wsi->user_space = NULL;
/* create the response packet */
/* make a buffer big enough for everything */
response = malloc(256 +
wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len +
wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len +
wsi->utf8_token[WSI_TOKEN_HOST].token_len +
wsi->utf8_token[WSI_TOKEN_ORIGIN].token_len +
wsi->utf8_token[WSI_TOKEN_GET_URI].token_len +
wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len);
if (!response) {
fprintf(stderr, "Out of memory for response buffer\n");
goto bail;
}
p = response;
strcpy(p, "HTTP/1.1 101 WebSocket Protocol Handshake\x0d\x0a"
"Upgrade: WebSocket\x0d\x0a");
p += strlen("HTTP/1.1 101 WebSocket Protocol Handshake\x0d\x0a"
"Upgrade: WebSocket\x0d\x0a");
strcpy(p, "Connection: Upgrade\x0d\x0a"
"Sec-WebSocket-Origin: ");
p += strlen("Connection: Upgrade\x0d\x0a"
"Sec-WebSocket-Origin: ");
strcpy(p, wsi->utf8_token[WSI_TOKEN_ORIGIN].token);
p += wsi->utf8_token[WSI_TOKEN_ORIGIN].token_len;
#ifdef LWS_OPENSSL_SUPPORT
if (wsi->ssl) {
strcpy(p, "\x0d\x0aSec-WebSocket-Location: wss://");
p += strlen("\x0d\x0aSec-WebSocket-Location: wss://");
} else {
#endif
strcpy(p, "\x0d\x0aSec-WebSocket-Location: ws://");
p += strlen("\x0d\x0aSec-WebSocket-Location: ws://");
#ifdef LWS_OPENSSL_SUPPORT
}
#endif
strcpy(p, wsi->utf8_token[WSI_TOKEN_HOST].token);
p += wsi->utf8_token[WSI_TOKEN_HOST].token_len;
strcpy(p, wsi->utf8_token[WSI_TOKEN_GET_URI].token);
p += wsi->utf8_token[WSI_TOKEN_GET_URI].token_len;
if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token) {
strcpy(p, "\x0d\x0aSec-WebSocket-Protocol: ");
p += strlen("\x0d\x0aSec-WebSocket-Protocol: ");
strcpy(p, wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
p += wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len;
}
strcpy(p, "\x0d\x0a\x0d\x0a");
p += strlen("\x0d\x0a\x0d\x0a");
/* convert the two keys into 32-bit integers */
if (interpret_key(wsi->utf8_token[WSI_TOKEN_KEY1].token, &key1))
goto bail;
if (interpret_key(wsi->utf8_token[WSI_TOKEN_KEY2].token, &key2))
goto bail;
/* lay them out in network byte order (MSB first */
sum[0] = key1 >> 24;
sum[1] = key1 >> 16;
sum[2] = key1 >> 8;
sum[3] = key1;
sum[4] = key2 >> 24;
sum[5] = key2 >> 16;
sum[6] = key2 >> 8;
sum[7] = key2;
/* follow them with the challenge token we were sent */
memcpy(&sum[8], wsi->utf8_token[WSI_TOKEN_CHALLENGE].token, 8);
/*
* compute the md5sum of that 16-byte series and use as our
* payload after our headers
*/
MD5(sum, 16, (unsigned char *)p);
p += 16;
/* it's complete: go ahead and send it */
debug("issuing response packet %d len\n", (int)(p - response));
#ifdef DEBUG
fwrite(response, 1, p - response, stderr);
#endif
n = libwebsocket_write(wsi, (unsigned char *)response,
p - response, LWS_WRITE_HTTP);
if (n < 0) {
fprintf(stderr, "ERROR writing to socket");
goto bail;
}
/* alright clean up and set ourselves into established state */
free(response);
wsi->state = WSI_STATE_ESTABLISHED;
wsi->lws_rx_parse_state = LWS_RXPS_NEW;
/* notify user code that we're ready to roll */
if (wsi->protocol->callback)
wsi->protocol->callback(wsi->protocol->owning_server,
wsi, LWS_CALLBACK_ESTABLISHED,
wsi->user_space, NULL, 0);
return 0;
bail:
return -1;
}
/*
* Perform the newer BASE64-encoded handshake scheme
*/
static int
handshake_0405(struct libwebsocket *wsi)
{
static const char *websocket_magic_guid_04 =
"258EAFA5-E914-47DA-95CA-C5AB0DC85B11";
static const char *websocket_magic_guid_04_masking =
"61AC5F19-FBBA-4540-B96F-6561F1AB40A8";
char accept_buf[MAX_WEBSOCKET_04_KEY_LEN + 37];
char nonce_buf[256];
char mask_summing_buf[256 + MAX_WEBSOCKET_04_KEY_LEN + 37];
unsigned char hash[20];
int n;
char *response;
char *p;
char *m = mask_summing_buf;
int nonce_len = 0;
int accept_len;
char *c;
char ext_name[128];
struct libwebsocket_extension * ext;
int ext_count = 0;
int more = 1;
if (!wsi->utf8_token[WSI_TOKEN_HOST].token_len ||
!wsi->utf8_token[WSI_TOKEN_KEY].token_len) {
debug("handshake_04 missing pieces\n");
/* completed header processing, but missing some bits */
goto bail;
}
if (wsi->utf8_token[WSI_TOKEN_EXTENSIONS].token_len) {
fprintf(stderr, "extensions not supported\n");
goto bail;
}
if (wsi->utf8_token[WSI_TOKEN_KEY].token_len >=
MAX_WEBSOCKET_04_KEY_LEN) {
fprintf(stderr, "Client sent handshake key longer "
"than max supported %d\n", MAX_WEBSOCKET_04_KEY_LEN);
goto bail;
}
strcpy(accept_buf, wsi->utf8_token[WSI_TOKEN_KEY].token);
strcpy(accept_buf + wsi->utf8_token[WSI_TOKEN_KEY].token_len,
websocket_magic_guid_04);
SHA1((unsigned char *)accept_buf,
wsi->utf8_token[WSI_TOKEN_KEY].token_len +
strlen(websocket_magic_guid_04), hash);
accept_len = lws_b64_encode_string((char *)hash, 20, accept_buf,
sizeof accept_buf);
if (accept_len < 0) {
fprintf(stderr, "Base64 encoded hash too long\n");
goto bail;
}
/* allocate the per-connection user memory (if any) */
if (wsi->protocol->per_session_data_size) {
wsi->user_space = malloc(
wsi->protocol->per_session_data_size);
if (wsi->user_space == NULL) {
fprintf(stderr, "Out of memory for "
"conn user space\n");
goto bail;
}
} else
wsi->user_space = NULL;
/* create the response packet */
/* make a buffer big enough for everything */
response = malloc(256 +
wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len +
wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len +
wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len);
if (!response) {
fprintf(stderr, "Out of memory for response buffer\n");
goto bail;
}
p = response;
strcpy(p, "HTTP/1.1 101 Switching Protocols\x0d\x0a"
"Upgrade: WebSocket\x0d\x0a");
p += strlen("HTTP/1.1 101 Switching Protocols\x0d\x0a"
"Upgrade: WebSocket\x0d\x0a");
strcpy(p, "Connection: Upgrade\x0d\x0a"
"Sec-WebSocket-Accept: ");
p += strlen("Connection: Upgrade\x0d\x0a"
"Sec-WebSocket-Accept: ");
strcpy(p, accept_buf);
p += accept_len;
if (wsi->ietf_spec_revision == 4) {
strcpy(p, "\x0d\x0aSec-WebSocket-Nonce: ");
p += strlen("\x0d\x0aSec-WebSocket-Nonce: ");
/* select the nonce */
n = libwebsockets_get_random(wsi->protocol->owning_server,
hash, 16);
if (n != 16) {
fprintf(stderr, "Unable to read random device %s %d\n",
SYSTEM_RANDOM_FILEPATH, n);
if (wsi->user_space)
free(wsi->user_space);
goto bail;
}
/* encode the nonce */
nonce_len = lws_b64_encode_string((const char *)hash, 16,
nonce_buf, sizeof nonce_buf);
if (nonce_len < 0) {
fprintf(stderr, "Failed to base 64 encode the nonce\n");
if (wsi->user_space)
free(wsi->user_space);
goto bail;
}
/* apply the nonce */
strcpy(p, nonce_buf);
p += nonce_len;
}
if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token) {
strcpy(p, "\x0d\x0aSec-WebSocket-Protocol: ");
p += strlen("\x0d\x0aSec-WebSocket-Protocol: ");
strcpy(p, wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
p += wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len;
}
/*
* Figure out which extensions the client has that we want to
* enable on this connection, and give him back the list
*/
if (wsi->utf8_token[WSI_TOKEN_EXTENSIONS].token_len) {
strcpy(p, "\x0d\x0aSec-WebSocket-Extensions: ");
p += strlen("\x0d\x0aSec-WebSocket-Extensions: ");
/*
* break down the list of client extensions
* and go through them
*/
c = wsi->utf8_token[WSI_TOKEN_EXTENSIONS].token;
n = 0;
while (more) {
if (*c && *c != ',') {
ext_name[n] = *c++;
if (n < sizeof(ext_name) - 1)
n++;
continue;
}
ext_name[n] = '\0';
if (!*c)
more = 0;
/* check a client's extension against our support */
ext = wsi->protocol->owning_server->extensions;
while (ext && ext->callback) {
if (strcmp(ext_name, ext->name)) {
ext++;
continue;
}
/*
* oh, we do support this one he
* asked for... but let's ask user
* code if it's OK to apply it on this
* particular connection + protocol
*/
n = wsi->protocol->owning_server->
protocols[0].callback(
wsi->protocol->owning_server,
wsi,
LWS_CALLBACK_CONFIRM_EXTENSION_OKAY,
wsi->user_space, ext_name, 0);
/*
* zero return from callback means
* go ahead and allow the extension,
* it's what we get if the callback is
* unhandled
*/
if (n) {
ext++;
continue;
}
/* apply it */
if (ext_count)
*p++ = ',';
p += sprintf(p, ext_name);
ext_count++;
/* instantiate the extension on this conn */
wsi->active_extensions_user[
wsi->count_active_extensions] =
malloc(ext->per_session_data_size);
wsi->active_extensions[
wsi->count_active_extensions] = ext;
/* allow him to construct his context */
ext->callback(wsi->protocol->owning_server,
wsi, LWS_EXT_CALLBACK_CONSTRUCT,
wsi->active_extensions_user[
wsi->count_active_extensions], NULL, 0);
wsi->count_active_extensions++;
ext++;
}
n = 0;
}
}
/* end of response packet */
strcpy(p, "\x0d\x0a\x0d\x0a");
p += strlen("\x0d\x0a\x0d\x0a");
if (wsi->ietf_spec_revision == 4) {
/*
* precompute the masking key the client will use from the SHA1
* hash of ( base 64 client key we were sent, concatenated with
* the bse 64 nonce we sent, concatenated with a magic constant
* guid specified by the 04 standard )
*
* We store the hash in the connection's wsi ready to use with
* undoing the masking the client has done on framed data it
* sends (we send our data to the client in clear).
*/
strcpy(mask_summing_buf, wsi->utf8_token[WSI_TOKEN_KEY].token);
m += wsi->utf8_token[WSI_TOKEN_KEY].token_len;
strcpy(m, nonce_buf);
m += nonce_len;
strcpy(m, websocket_magic_guid_04_masking);
m += strlen(websocket_magic_guid_04_masking);
SHA1((unsigned char *)mask_summing_buf, m - mask_summing_buf,
wsi->masking_key_04);
}
/* okay send the handshake response accepting the connection */
debug("issuing response packet %d len\n", (int)(p - response));
#ifdef DEBUG
fwrite(response, 1, p - response, stderr);
#endif
n = libwebsocket_write(wsi, (unsigned char *)response,
p - response, LWS_WRITE_HTTP);
if (n < 0) {
fprintf(stderr, "ERROR writing to socket");
goto bail;
}
/* alright clean up and set ourselves into established state */
free(response);
wsi->state = WSI_STATE_ESTABLISHED;
wsi->lws_rx_parse_state = LWS_RXPS_NEW;
wsi->rx_packet_length = 0;
/* notify user code that we're ready to roll */
if (wsi->protocol->callback)
wsi->protocol->callback(wsi->protocol->owning_server,
wsi, LWS_CALLBACK_ESTABLISHED,
wsi->user_space, NULL, 0);
return 0;
bail:
return -1;
}
/*
* -04 of the protocol (actually the 80th version) has a radically different
* handshake. The 04 spec gives the following idea
*
* The handshake from the client looks as follows:
*
* GET /chat HTTP/1.1
* Host: server.example.com
* Upgrade: websocket
* Connection: Upgrade
* Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==
* Sec-WebSocket-Origin: http://example.com
* Sec-WebSocket-Protocol: chat, superchat
* Sec-WebSocket-Version: 4
*
* The handshake from the server looks as follows:
*
* HTTP/1.1 101 Switching Protocols
* Upgrade: websocket
* Connection: Upgrade
* Sec-WebSocket-Accept: me89jWimTRKTWwrS3aRrL53YZSo=
* Sec-WebSocket-Nonce: AQIDBAUGBwgJCgsMDQ4PEC==
* Sec-WebSocket-Protocol: chat
*/
/*
* We have to take care about parsing because the headers may be split
* into multiple fragments. They may contain unknown headers with arbitrary
* argument lengths. So, we parse using a single-character at a time state
* machine that is completely independent of packet size.
*/
int
libwebsocket_read(struct libwebsocket_context *context, struct libwebsocket *wsi,
unsigned char * buf, size_t len)
{
size_t n;
switch (wsi->state) {
case WSI_STATE_HTTP:
wsi->state = WSI_STATE_HTTP_HEADERS;
wsi->parser_state = WSI_TOKEN_NAME_PART;
/* fallthru */
case WSI_STATE_HTTP_HEADERS:
debug("issuing %d bytes to parser\n", (int)len);
#ifdef DEBUG
fwrite(buf, 1, len, stderr);
#endif
switch (wsi->mode) {
case LWS_CONNMODE_WS_CLIENT:
for (n = 0; n < len; n++)
libwebsocket_client_rx_sm(wsi, *buf++);
return 0;
default:
break;
}
/* LWS_CONNMODE_WS_SERVING */
for (n = 0; n < len; n++)
libwebsocket_parse(wsi, *buf++);
if (wsi->parser_state != WSI_PARSING_COMPLETE)
break;
debug("libwebsocket_parse sees parsing complete\n");
/* is this websocket protocol or normal http 1.0? */
if (!wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len ||
!wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len) {
if (wsi->protocol->callback)
(wsi->protocol->callback)(context, wsi,
LWS_CALLBACK_HTTP, wsi->user_space,
wsi->utf8_token[WSI_TOKEN_GET_URI].token, 0);
wsi->state = WSI_STATE_HTTP;
return 0;
}
/*
* It's websocket
*
* Make sure user side is happy about protocol
*/
while (wsi->protocol->callback) {
if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL) {
if (wsi->protocol->name == NULL)
break;
} else
if (strcmp(
wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
wsi->protocol->name) == 0)
break;
wsi->protocol++;
}
/* we didn't find a protocol he wanted? */
if (wsi->protocol->callback == NULL) {
if (wsi->utf8_token[WSI_TOKEN_PROTOCOL].token == NULL)
fprintf(stderr, "[no protocol] "
"not supported (use NULL .name)\n");
else
fprintf(stderr, "Requested protocol %s "
"not supported\n",
wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
goto bail;
}
/*
* find out which spec version the client is using
* if this header is not given, we default to 00 (aka 76)
*/
if (wsi->utf8_token[WSI_TOKEN_VERSION].token_len)
wsi->ietf_spec_revision =
atoi(wsi->utf8_token[WSI_TOKEN_VERSION].token);
/*
* Give the user code a chance to study the request and
* have the opportunity to deny it
*/
if ((wsi->protocol->callback)(wsi->protocol->owning_server, wsi,
LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION,
&wsi->utf8_token[0], NULL, 0)) {
fprintf(stderr, "User code denied connection\n");
goto bail;
}
/*
* Perform the handshake according to the protocol version the
* client announced
*/
switch (wsi->ietf_spec_revision) {
case 0: /* applies to 76 and 00 */
wsi->xor_mask = xor_no_mask;
if (handshake_00(wsi))
goto bail;
break;
case 4: /* 04 */
wsi->xor_mask = xor_mask_04;
debug("libwebsocket_parse calling handshake_04\n");
if (handshake_0405(wsi))
goto bail;
break;
case 5:
case 6:
wsi->xor_mask = xor_mask_05;
debug("libwebsocket_parse calling handshake_04\n");
if (handshake_0405(wsi))
goto bail;
break;
default:
fprintf(stderr, "Unknown client spec version %d\n",
wsi->ietf_spec_revision);
goto bail;
}
fprintf(stderr, "accepted v%02d connection\n",
wsi->ietf_spec_revision);
break;
case WSI_STATE_ESTABLISHED:
switch (wsi->mode) {
case LWS_CONNMODE_WS_CLIENT:
for (n = 0; n < len; n++)
libwebsocket_client_rx_sm(wsi, *buf++);
return 0;
default:
break;
}
/* LWS_CONNMODE_WS_SERVING */
if (libwebsocket_interpret_incoming_packet(wsi, buf, len) < 0)
goto bail;
break;
default:
break;
}
return 0;
bail:
libwebsocket_close_and_free_session(context, wsi,
LWS_CLOSE_STATUS_NOSTATUS);
return -1;
}