char *
libwebsockets_generate_client_handshake(struct libwebsocket_context *context,
struct libwebsocket *wsi, char *pkt)
{
char buf[128];
char hash[20];
char key_b64[40];
char *p = pkt;
int n;
#ifndef LWS_NO_EXTENSIONS
struct libwebsocket_extension *ext;
int ext_count = 0;
#endif
/*
* create the random key
*/
n = libwebsockets_get_random(context, hash, 16);
if (n != 16) {
lwsl_err("Unable to read from random dev %s\n",
SYSTEM_RANDOM_FILEPATH);
libwebsocket_close_and_free_session(context, wsi,
LWS_CLOSE_STATUS_NOSTATUS);
return NULL;
}
lws_b64_encode_string(hash, 16, key_b64, sizeof(key_b64));
/*
* 00 example client handshake
*
* GET /socket.io/websocket HTTP/1.1
* Upgrade: WebSocket
* Connection: Upgrade
* Host: 127.0.0.1:9999
* Origin: http://127.0.0.1
* Sec-WebSocket-Key1: 1 0 2#0W 9 89 7 92 ^
* Sec-WebSocket-Key2: 7 7Y 4328 B2v[8(z1
* Cookie: socketio=websocket
*
* (Á®Ä0¶†≥
*
* 04 example client handshake
*
* 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
*/
p += sprintf(p, "GET %s HTTP/1.1\x0d\x0a",
lws_hdr_simple_ptr(wsi, _WSI_TOKEN_CLIENT_URI));
p += sprintf(p,
"Pragma: no-cache\x0d\x0a""Cache-Control: no-cache\x0d\x0a");
p += sprintf(p, "Host: %s\x0d\x0a",
lws_hdr_simple_ptr(wsi, _WSI_TOKEN_CLIENT_HOST));
p += sprintf(p,
"Upgrade: websocket\x0d\x0a""Connection: Upgrade\x0d\x0a""Sec-WebSocket-Key: ");
strcpy(p, key_b64);
p += strlen(key_b64);
p += sprintf(p, "\x0d\x0a");
if (lws_hdr_simple_ptr(wsi, _WSI_TOKEN_CLIENT_ORIGIN))
p += sprintf(p, "Origin: http://%s\x0d\x0a",
lws_hdr_simple_ptr(wsi, _WSI_TOKEN_CLIENT_ORIGIN));
if (lws_hdr_simple_ptr(wsi, _WSI_TOKEN_CLIENT_SENT_PROTOCOLS))
p += sprintf(p, "Sec-WebSocket-Protocol: %s\x0d\x0a",
lws_hdr_simple_ptr(wsi, _WSI_TOKEN_CLIENT_SENT_PROTOCOLS));
/* tell the server what extensions we could support */
p += sprintf(p, "Sec-WebSocket-Extensions: ");
#ifndef LWS_NO_EXTENSIONS
ext = context->extensions;
while (ext && ext->callback) {
n = lws_ext_callback_for_each_extension_type(context, wsi,
LWS_EXT_CALLBACK_CHECK_OK_TO_PROPOSE_EXTENSION,
(char *)ext->name, 0);
if (n) { /* an extension vetos us */
lwsl_ext("ext %s vetoed\n", (char *)ext->name);
ext++;
continue;
}
n = context->protocols[0].callback(context, wsi,
LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED,
wsi->user_space, (char *)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, "%s", ext->name);
ext_count++;
ext++;
}
#endif
p += sprintf(p, "\x0d\x0a");
if (wsi->ietf_spec_revision)
p += sprintf(p, "Sec-WebSocket-Version: %d\x0d\x0a",
wsi->ietf_spec_revision);
/* give userland a chance to append, eg, cookies */
context->protocols[0].callback(context, wsi,
LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER,
NULL, &p, (pkt + sizeof(context->service_buffer)) - p - 12);
p += sprintf(p, "\x0d\x0a");
/* prepare the expected server accept response */
key_b64[39] = '\0'; /* enforce composed length below buf sizeof */
n = sprintf(buf, "%s258EAFA5-E914-47DA-95CA-C5AB0DC85B11", key_b64);
libwebsockets_SHA1((unsigned char *)buf, n, (unsigned char *)hash);
lws_b64_encode_string(hash, 20,
wsi->u.hdr.ah->initial_handshake_hash_base64,
sizeof(wsi->u.hdr.ah->initial_handshake_hash_base64));
return p;
}
int
handshake_0405(struct libwebsocket_context *context, struct libwebsocket *wsi)
{
unsigned char hash[20];
int n;
char *response;
char *p;
int accept_len;
if (!lws_hdr_total_length(wsi, WSI_TOKEN_HOST) ||
!lws_hdr_total_length(wsi, WSI_TOKEN_KEY)) {
lwsl_parser("handshake_04 missing pieces\n");
/* completed header processing, but missing some bits */
goto bail;
}
if (lws_hdr_total_length(wsi, WSI_TOKEN_KEY) >=
MAX_WEBSOCKET_04_KEY_LEN) {
lwsl_warn("Client key too long %d\n", MAX_WEBSOCKET_04_KEY_LEN);
goto bail;
}
/*
* since key length is restricted above (currently 128), cannot
* overflow
*/
n = sprintf((char *)context->service_buffer,
"%s258EAFA5-E914-47DA-95CA-C5AB0DC85B11",
lws_hdr_simple_ptr(wsi, WSI_TOKEN_KEY));
libwebsockets_SHA1(context->service_buffer, n, hash);
accept_len = lws_b64_encode_string((char *)hash, 20,
(char *)context->service_buffer,
sizeof(context->service_buffer));
if (accept_len < 0) {
lwsl_warn("Base64 encoded hash too long\n");
goto bail;
}
/* allocate the per-connection user memory (if any) */
if (libwebsocket_ensure_user_space(wsi))
goto bail;
/* create the response packet */
/* make a buffer big enough for everything */
response = (char *)context->service_buffer + MAX_WEBSOCKET_04_KEY_LEN + LWS_SEND_BUFFER_PRE_PADDING;
p = response;
LWS_CPYAPP(p, "HTTP/1.1 101 Switching Protocols\x0d\x0a"
"Upgrade: WebSocket\x0d\x0a"
"Connection: Upgrade\x0d\x0a"
"Sec-WebSocket-Accept: ");
strcpy(p, (char *)context->service_buffer);
p += accept_len;
if (lws_hdr_total_length(wsi, WSI_TOKEN_PROTOCOL)) {
LWS_CPYAPP(p, "\x0d\x0aSec-WebSocket-Protocol: ");
n = lws_hdr_copy(wsi, p, 128, WSI_TOKEN_PROTOCOL);
if (n < 0)
goto bail;
p += n;
}
#ifndef LWS_NO_EXTENSIONS
/*
* Figure out which extensions the client has that we want to
* enable on this connection, and give him back the list
*/
if (lws_extension_server_handshake(context, wsi, &p))
goto bail;
#endif
//LWS_CPYAPP(p, "\x0d\x0a""An-unknown-header: blah");
/* end of response packet */
LWS_CPYAPP(p, "\x0d\x0a\x0d\x0a");
if (!lws_any_extension_handled(context, wsi,
LWS_EXT_CALLBACK_HANDSHAKE_REPLY_TX,
response, p - response)) {
/* okay send the handshake response accepting the connection */
lwsl_parser("issuing resp pkt %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_HEADERS);
if (n != (p - response)) {
lwsl_debug("handshake_0405: ERROR writing to socket\n");
goto bail;
}
}
/* alright clean up and set ourselves into established state */
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:
/* free up his parsing allocations */
lws_free_header_table(wsi);
return -1;
}