lib/client.c

/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010-2013 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"

#ifdef WIN32
#include <tchar.h>
#include <io.h>
#else
#ifdef LWS_BUILTIN_GETIFADDRS
#include <getifaddrs.h>
#else
#include <ifaddrs.h>
#endif
#include <sys/un.h>
#include <sys/socket.h>
#include <netdb.h>
#endif

#ifdef LWS_OPENSSL_SUPPORT
extern int openssl_websocket_private_data_index;
#endif				  

int lws_client_socket_service(struct libwebsocket_context *context, struct libwebsocket *wsi, struct pollfd *pollfd)
{
	int n;
	char pkt[1024];
	char *p = &pkt[0];
	int len;
	char c;
#ifdef LWS_OPENSSL_SUPPORT
	char ssl_err_buf[512];
#endif

	switch (wsi->mode) {

	case LWS_CONNMODE_WS_CLIENT_WAITING_PROXY_REPLY:

		/* handle proxy hung up on us */

		if (pollfd->revents & (POLLERR | POLLHUP)) {

			lwsl_warn("Proxy connection %p (fd=%d) dead\n",
				(void *)wsi, pollfd->fd);

			libwebsocket_close_and_free_session(context, wsi,
						     LWS_CLOSE_STATUS_NOSTATUS);
			return 0;
		}

		n = recv(wsi->sock, pkt, sizeof pkt, 0);
		if (n < 0) {
			libwebsocket_close_and_free_session(context, wsi,
						     LWS_CLOSE_STATUS_NOSTATUS);
			lwsl_err("ERROR reading from proxy socket\n");
			return 0;
		}

		pkt[13] = '\0';
		if (strcmp(pkt, "HTTP/1.0 200 ") != 0) {
			libwebsocket_close_and_free_session(context, wsi,
						     LWS_CLOSE_STATUS_NOSTATUS);
			lwsl_err("ERROR from proxy: %s\n", pkt);
			return 0;
		}

		/* clear his proxy connection timeout */

		libwebsocket_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);

		/* fallthru */

	case LWS_CONNMODE_WS_CLIENT_ISSUE_HANDSHAKE:

		/*
		 * we are under PENDING_TIMEOUT_SENT_CLIENT_HANDSHAKE
		 * timeout protection set in client-handshake.c
		 */

	#ifdef LWS_OPENSSL_SUPPORT

		/*
		 * take care of our libwebsocket_callback_on_writable
		 * happening at a time when there's no real connection yet
		 */

		pollfd->events &= ~POLLOUT;

		/* external POLL support via protocol 0 */
		context->protocols[0].callback(context, wsi,
			LWS_CALLBACK_CLEAR_MODE_POLL_FD,
			(void *)(long)wsi->sock, NULL, POLLOUT);

		/* we can retry this... so just cook the SSL BIO the first time */

		if (wsi->use_ssl && !wsi->ssl) {

			wsi->ssl = SSL_new(context->ssl_client_ctx);
			wsi->client_bio = BIO_new_socket(wsi->sock,
								   BIO_NOCLOSE);
			SSL_set_bio(wsi->ssl, wsi->client_bio, wsi->client_bio);

			SSL_set_ex_data(wsi->ssl,
					openssl_websocket_private_data_index,
								       context);
		}		

		if (wsi->use_ssl) {
			n = SSL_connect(wsi->ssl);

			if (n < 0) {
				n = SSL_get_error(wsi->ssl, n);

				if (n == SSL_ERROR_WANT_READ ||
					n == SSL_ERROR_WANT_WRITE) {
					/*
					 * wants us to retry connect due to state of the
					 * underlying ssl layer... but since it may be
					 * stalled on blocked write, no incoming data may
					 * arrive to trigger the retry.  Force (possibly
					 * many if the SSL state persists in returning the
					 * condition code, but other sockets are getting
					 * serviced inbetweentimes) us to get called back
					 * when writable.
					 */

					lwsl_info("SSL_connect -> SSL_ERROR_WANT_... retrying\n");
					libwebsocket_callback_on_writable(context, wsi);

					return 0; /* no error */
				}
				n = -1;
			}

			if (n <= 0) {
				/*
				 * retry if new data comes until we
				 * run into the connection timeout or win
				 */

				lwsl_err("SSL connect error %s\n",
					ERR_error_string(ERR_get_error(),
								  ssl_err_buf));
				return 0;
			}

			n = SSL_get_verify_result(wsi->ssl);
			if ((n != X509_V_OK) && (
				n != X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT ||
							   wsi->use_ssl != 2)) {

				lwsl_err("server's cert didn't "
							   "look good %d\n", n);
				libwebsocket_close_and_free_session(context,
						wsi, LWS_CLOSE_STATUS_NOSTATUS);
				return 0;
			}
		} else
			wsi->ssl = NULL;
	#endif

		p = libwebsockets_generate_client_handshake(context, wsi, p);
		if (p == NULL) {
			lwsl_err("Failed to generate handshake for client, closing it\n");
			libwebsocket_close_and_free_session(context, wsi,
						     LWS_CLOSE_STATUS_NOSTATUS);
			return 0;
		}

		/* send our request to the server */

	#ifdef LWS_OPENSSL_SUPPORT
		if (wsi->use_ssl)
			n = SSL_write(wsi->ssl, pkt, p - pkt);
		else
	#endif
			n = send(wsi->sock, pkt, p - pkt, 0);

		if (n < 0) {
			lwsl_debug("ERROR writing to client socket\n");
			libwebsocket_close_and_free_session(context, wsi,
						     LWS_CLOSE_STATUS_NOSTATUS);
			return 0;
		}

		wsi->parser_state = WSI_TOKEN_NAME_PART;
		wsi->mode = LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY;
		libwebsocket_set_timeout(wsi,
				PENDING_TIMEOUT_AWAITING_SERVER_RESPONSE, AWAITING_TIMEOUT);

		break;

	case LWS_CONNMODE_WS_CLIENT_WAITING_SERVER_REPLY:

		/* handle server hung up on us */

		if (pollfd->revents & (POLLERR | POLLHUP)) {

			lwsl_debug("Server connection %p (fd=%d) dead\n",
				(void *)wsi, pollfd->fd);

			goto bail3;
		}


		/* interpret the server response */

		/*
		 *  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 some care here to only take from the
		 * socket bytewise.  The browser may (and has been seen to
		 * in the case that onopen() performs websocket traffic)
		 * coalesce both handshake response and websocket traffic
		 * in one packet, since at that point the connection is
		 * definitively ready from browser pov.
		 */

		len = 1;
		while (wsi->parser_state != WSI_PARSING_COMPLETE && len > 0) {
#ifdef LWS_OPENSSL_SUPPORT
			if (wsi->use_ssl)
				len = SSL_read(wsi->ssl, &c, 1);
			 else
#endif
				len = recv(wsi->sock, &c, 1, 0);

			libwebsocket_parse(wsi, c);
		}

		/*
		 * hs may also be coming in multiple packets, there is a 5-sec
		 * libwebsocket timeout still active here too, so if parsing did
		 * not complete just wait for next packet coming in this state
		 */

		if (wsi->parser_state != WSI_PARSING_COMPLETE)
			break;

		/*
		 * otherwise deal with the handshake.  If there's any
		 * packet traffic already arrived we'll trigger poll() again
		 * right away and deal with it that way
		 */

		return lws_client_interpret_server_handshake(context, wsi);

bail3:
		if (wsi->c_protocol)
			free(wsi->c_protocol);
		libwebsocket_close_and_free_session(context, wsi,
						    LWS_CLOSE_STATUS_NOSTATUS);
		return 0;

	case LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT:
		lwsl_ext("LWS_CONNMODE_WS_CLIENT_WAITING_EXTENSION_CONNECT\n");
		break;

	case LWS_CONNMODE_WS_CLIENT_PENDING_CANDIDATE_CHILD:
		lwsl_ext("LWS_CONNMODE_WS_CLIENT_PENDING_CANDIDATE_CHILD\n");
		break;
	default:
		break;
	}

	return 0;
}


/*
 * In-place str to lower case
 */

static void
strtolower(char *s)
{
	while (*s) {
		*s = tolower(*s);
		s++;
	}
}

int
lws_client_interpret_server_handshake(struct libwebsocket_context *context,
		struct libwebsocket *wsi)
{
	unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 1 +
			MAX_BROADCAST_PAYLOAD + LWS_SEND_BUFFER_POST_PADDING];
	char pkt[1024];
	char *p = &pkt[0];
	const char *pc;
	const char *c;
	int more = 1;
	int okay = 0;
	char ext_name[128];
	struct libwebsocket_extension *ext;
	void *v;
	int len = 0;
	int n;
	static const char magic_websocket_04_masking_guid[] =
					 "61AC5F19-FBBA-4540-B96F-6561F1AB40A8";

	/*
	 * 00 / 76 -->
	 *
	 * HTTP/1.1 101 WebSocket Protocol Handshake
	 * Upgrade: WebSocket
	 * Connection: Upgrade
	 * Sec-WebSocket-Origin: http://127.0.0.1
	 * Sec-WebSocket-Location: ws://127.0.0.1:9999/socket.io/websocket
	 *
	 * xxxxxxxxxxxxxxxx
	 */

	if (wsi->ietf_spec_revision == 0) {
		if (!wsi->utf8_token[WSI_TOKEN_HTTP].token_len ||
			!wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len ||
			!wsi->utf8_token[WSI_TOKEN_CHALLENGE].token_len ||
			!wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len ||
			(!wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len &&
			wsi->c_protocol != NULL)) {
			lwsl_parser("libwebsocket_client_handshake "
					"missing required header(s)\n");
			pkt[len] = '\0';
			lwsl_parser("%s", pkt);
			goto bail3;
		}

		strtolower(wsi->utf8_token[WSI_TOKEN_HTTP].token);
		if (strncmp(wsi->utf8_token[WSI_TOKEN_HTTP].token, "101", 3)) {
			lwsl_warn("libwebsocket_client_handshake "
				"server sent bad HTTP response '%s'\n",
				wsi->utf8_token[WSI_TOKEN_HTTP].token);
			goto bail3;
		}

		if (wsi->utf8_token[WSI_TOKEN_CHALLENGE].token_len < 16) {
			lwsl_parser("libwebsocket_client_handshake "
				"challenge reply too short %d\n",
				wsi->utf8_token[
					WSI_TOKEN_CHALLENGE].token_len);
			pkt[len] = '\0';
			lwsl_parser("%s", pkt);
			goto bail3;

		}

		goto select_protocol;
	}

	/*
	 * well, what the server sent looked reasonable for syntax.
	 * Now let's confirm it sent all the necessary headers
	 */
#if 0
	lwsl_parser("WSI_TOKEN_HTTP: %d\n",
				    wsi->utf8_token[WSI_TOKEN_HTTP].token_len);
	lwsl_parser("WSI_TOKEN_UPGRADE: %d\n",
				 wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len);
	lwsl_parser("WSI_TOKEN_CONNECTION: %d\n",
			      wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len);
	lwsl_parser("WSI_TOKEN_ACCEPT: %d\n",
				  wsi->utf8_token[WSI_TOKEN_ACCEPT].token_len);
	lwsl_parser("WSI_TOKEN_NONCE: %d\n",
				   wsi->utf8_token[WSI_TOKEN_NONCE].token_len);
	lwsl_parser("WSI_TOKEN_PROTOCOL: %d\n",
				wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len);
#endif
	if (!wsi->utf8_token[WSI_TOKEN_HTTP].token_len ||
	    !wsi->utf8_token[WSI_TOKEN_UPGRADE].token_len ||
	    !wsi->utf8_token[WSI_TOKEN_CONNECTION].token_len ||
	    !wsi->utf8_token[WSI_TOKEN_ACCEPT].token_len ||
	    (!wsi->utf8_token[WSI_TOKEN_NONCE].token_len &&
				   wsi->ietf_spec_revision == 4) ||
	    (!wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len &&
						    wsi->c_protocol != NULL)) {
		lwsl_parser("libwebsocket_client_handshake "
					"missing required header(s)\n");
		pkt[len] = '\0';
		lwsl_parser("%s", pkt);
		goto bail3;
	}

	/*
	 * Everything seems to be there, now take a closer look at what
	 * is in each header
	 */

	strtolower(wsi->utf8_token[WSI_TOKEN_HTTP].token);
	if (strncmp(wsi->utf8_token[WSI_TOKEN_HTTP].token, "101", 3)) {
		lwsl_warn("libwebsocket_client_handshake "
				"server sent bad HTTP response '%s'\n",
				 wsi->utf8_token[WSI_TOKEN_HTTP].token);
		goto bail3;
	}

	strtolower(wsi->utf8_token[WSI_TOKEN_UPGRADE].token);
	if (strcmp(wsi->utf8_token[WSI_TOKEN_UPGRADE].token,
							 "websocket")) {
		lwsl_warn("libwebsocket_client_handshake server "
				"sent bad Upgrade header '%s'\n",
				  wsi->utf8_token[WSI_TOKEN_UPGRADE].token);
		goto bail3;
	}

	strtolower(wsi->utf8_token[WSI_TOKEN_CONNECTION].token);
	if (strcmp(wsi->utf8_token[WSI_TOKEN_CONNECTION].token,
							   "upgrade")) {
		lwsl_warn("libwebsocket_client_handshake server "
				"sent bad Connection hdr '%s'\n",
			   wsi->utf8_token[WSI_TOKEN_CONNECTION].token);
		goto bail3;
	}

select_protocol:
	pc = wsi->c_protocol;
	if (pc == NULL)
		lwsl_parser("lws_client_interpret_server_handshake: "
							  "NULL c_protocol\n");
	else
		lwsl_parser("lws_client_interpret_server_handshake: "
						      "cPprotocol='%s'\n", pc);

	/*
	 * confirm the protocol the server wants to talk was in the list
	 * of protocols we offered
	 */

	if (!wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len) {

		lwsl_warn("lws_client_interpret_server_handshake "
					       "WSI_TOKEN_PROTOCOL is null\n");
		/*
		 * no protocol name to work from,
		 * default to first protocol
		 */
		wsi->protocol = &context->protocols[0];
		wsi->c_callback = wsi->protocol->callback;
		free(wsi->c_protocol);

		goto check_extensions;
	}

	while (*pc && !okay) {
		if ((!strncmp(pc, wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
		 wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len)) &&
		 (pc[wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len] == ',' ||
		  pc[wsi->utf8_token[WSI_TOKEN_PROTOCOL].token_len] == '\0')) {
			okay = 1;
			continue;
		}
		while (*pc && *pc != ',')
			pc++;
		while (*pc && *pc != ' ')
			pc++;
	}

	/* done with him now */

	if (wsi->c_protocol)
		free(wsi->c_protocol);

	if (!okay) {
		lwsl_err("libwebsocket_client_handshake server "
					"sent bad protocol '%s'\n",
				 wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
		goto bail2;
	}

	/*
	 * identify the selected protocol struct and set it
	 */
	n = 0;
	wsi->protocol = NULL;
	while (context->protocols[n].callback && !wsi->protocol) {  /* Stop after finding first one?? */
		if (strcmp(wsi->utf8_token[WSI_TOKEN_PROTOCOL].token,
					   context->protocols[n].name) == 0) {
			wsi->protocol = &context->protocols[n];
			wsi->c_callback = wsi->protocol->callback;
		}
		n++;
	}

	if (wsi->protocol == NULL) {
		lwsl_err("libwebsocket_client_handshake server "
				"requested protocol '%s', which we "
				"said we supported but we don't!\n",
				 wsi->utf8_token[WSI_TOKEN_PROTOCOL].token);
		goto bail2;
	}


check_extensions:

	/* instantiate the accepted extensions */

	if (!wsi->utf8_token[WSI_TOKEN_EXTENSIONS].token_len) {
		lwsl_ext("no client extenstions allowed by server\n");
		goto check_accept;
	}

	/*
	 * break down the list of server accepted extensions
	 * and go through matching them or identifying bogons
	 */

	c = wsi->utf8_token[WSI_TOKEN_EXTENSIONS].token;
	n = 0;
	while (more) {

		if (*c && (*c != ',' && *c != ' ' && *c != '\t')) {
			ext_name[n] = *c++;
			if (n < sizeof(ext_name) - 1)
				n++;
			continue;
		}
		ext_name[n] = '\0';
		if (!*c)
			more = 0;
		else {
			c++;
			if (!n)
				continue;
		}

		/* check we actually support it */

		lwsl_ext("checking client ext %s\n", ext_name);

		n = 0;
		ext = wsi->protocol->owning_server->extensions;
		while (ext && ext->callback) {

			if (strcmp(ext_name, ext->name)) {
				ext++;
				continue;
			}

			n = 1;

			lwsl_ext("instantiating client ext %s\n", ext_name);

			/* instantiate the extension on this conn */

			wsi->active_extensions_user[
				wsi->count_active_extensions] =
					 malloc(ext->per_session_data_size);
			if (wsi->active_extensions_user[
				wsi->count_active_extensions] == NULL) {
				lwsl_err("Out of mem\n");
				goto bail2;
			}
			memset(wsi->active_extensions_user[
				wsi->count_active_extensions], 0,
						    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,
				ext, wsi,
				   LWS_EXT_CALLBACK_CLIENT_CONSTRUCT,
					wsi->active_extensions_user[
					 wsi->count_active_extensions],
								   NULL, 0);

			wsi->count_active_extensions++;

			ext++;
		}

		if (n == 0) {
			lwsl_warn("Server said we should use"
				  "an unknown extension '%s'!\n", ext_name);
			goto bail2;
		}

		n = 0;
	}


check_accept:

	if (wsi->ietf_spec_revision == 0) {

		if (memcmp(wsi->initial_handshake_hash_base64,
			  wsi->utf8_token[WSI_TOKEN_CHALLENGE].token, 16)) {
			lwsl_warn("libwebsocket_client_handshake "
					   "failed 00 challenge compare\n");
				pkt[len] = '\0';
				lwsl_warn("%s", pkt);
				goto bail2;
		}

		goto accept_ok;
	}

	/*
	 * Confirm his accept token is the one we precomputed
	 */

	if (strcmp(wsi->utf8_token[WSI_TOKEN_ACCEPT].token,
				  wsi->initial_handshake_hash_base64)) {
		lwsl_warn("libwebsocket_client_handshake server "
			"sent bad ACCEPT '%s' vs computed '%s'\n",
			wsi->utf8_token[WSI_TOKEN_ACCEPT].token,
					wsi->initial_handshake_hash_base64);
		goto bail2;
	}

	if (wsi->ietf_spec_revision == 4) {
		/*
		 * Calculate the 04 masking key to use when
		 * sending data to server
		 */

		strcpy((char *)buf, wsi->key_b64);
		p = (char *)buf + strlen(wsi->key_b64);
		strcpy(p, wsi->utf8_token[WSI_TOKEN_NONCE].token);
		p += wsi->utf8_token[WSI_TOKEN_NONCE].token_len;
		strcpy(p, magic_websocket_04_masking_guid);
		SHA1(buf, strlen((char *)buf), wsi->masking_key_04);
	}
accept_ok:

	/* allocate the per-connection user memory (if any) */
	if (wsi->protocol->per_session_data_size &&
					  !libwebsocket_ensure_user_space(wsi))
		goto bail2;

	/* clear his proxy connection timeout */

	libwebsocket_set_timeout(wsi, NO_PENDING_TIMEOUT, 0);

	/* mark him as being alive */

	wsi->state = WSI_STATE_ESTABLISHED;
	wsi->mode = LWS_CONNMODE_WS_CLIENT;

	lwsl_debug("handshake OK for protocol %s\n", wsi->protocol->name);

	/* call him back to inform him he is up */

	wsi->protocol->callback(context, wsi,
				LWS_CALLBACK_CLIENT_ESTABLISHED,
						     wsi->user_space, NULL, 0);

	/*
	 * inform all extensions, not just active ones since they
	 * already know
	 */

	ext = context->extensions;

	while (ext && ext->callback) {
		v = NULL;
		for (n = 0; n < wsi->count_active_extensions; n++)
			if (wsi->active_extensions[n] == ext)
				v = wsi->active_extensions_user[n];

		ext->callback(context, ext, wsi,
			  LWS_EXT_CALLBACK_ANY_WSI_ESTABLISHED, v, NULL, 0);
		ext++;
	}

	return 0;

bail3:
	if (wsi->c_protocol)
		free(wsi->c_protocol);

bail2:
	if (wsi->c_callback) wsi->c_callback(context, wsi,
       LWS_CALLBACK_CLIENT_CONNECTION_ERROR,
			 wsi->user_space,
			 NULL, 0);
	libwebsocket_close_and_free_session(context, wsi,
						 LWS_CLOSE_STATUS_NOSTATUS);  // But this should be LWS_CLOSE_STATUS_PROTOCOL_ERR

	return 1;
}

void libwebsockets_00_spaceout(char *key, int spaces, int seed)
{
	char *p;

	key++;
	while (spaces--) {
		if (*key && (seed & 1))
			key++;
		seed >>= 1;

		p = key + strlen(key);
		while (p >= key) {
			p[1] = p[0];
			p--;
		}
		*key++ = ' ';
	}
}

void libwebsockets_00_spam(char *key, int count, int seed)
{
	char *p;

	key++;
	while (count--) {

		if (*key && (seed & 1))
			key++;
		seed >>= 1;

		p = key + strlen(key);
		while (p >= key) {
			p[1] = p[0];
			p--;
		}
		*key++ = 0x21 + ((seed & 0xffff) % 15);
		/* 4 would use it up too fast.. not like it matters */
		seed >>= 1;
	}
}

char *
libwebsockets_generate_client_handshake(struct libwebsocket_context *context,
		struct libwebsocket *wsi, char *pkt)
{
	char hash[20];
	char *p = pkt;
	int n;
	struct libwebsocket_extension *ext;
	struct libwebsocket_extension *ext1;
	int ext_count = 0;
	unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 1 +
			 MAX_BROADCAST_PAYLOAD + LWS_SEND_BUFFER_POST_PADDING];
	static const char magic_websocket_guid[] =
					 "258EAFA5-E914-47DA-95CA-C5AB0DC85B11";

	/*
	 * 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);
		free(wsi->c_path);
		free(wsi->c_host);
		if (wsi->c_origin)
			free(wsi->c_origin);
		if (wsi->c_protocol)
			free(wsi->c_protocol);
		libwebsocket_close_and_free_session(context, wsi,
					     LWS_CLOSE_STATUS_NOSTATUS);
		return NULL;
	}

	lws_b64_encode_string(hash, 16, wsi->key_b64,
						   sizeof wsi->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", wsi->c_path);

	p += sprintf(p, "Pragma: no-cache\x0d\x0a"
					"Cache-Control: no-cache\x0d\x0a");

	if (wsi->ietf_spec_revision == 0) {
		unsigned char spaces_1, spaces_2;
		unsigned int max_1, max_2;
		unsigned int num_1, num_2;
		unsigned long product_1, product_2;
		char key_1[40];
		char key_2[40];
		unsigned int seed;
		unsigned int count;
		char challenge[16];

		libwebsockets_get_random(context, &spaces_1, sizeof(char));
		libwebsockets_get_random(context, &spaces_2, sizeof(char));

		spaces_1 = (spaces_1 % 12) + 1;
		spaces_2 = (spaces_2 % 12) + 1;

		max_1 = 4294967295 / spaces_1;
		max_2 = 4294967295 / spaces_2;

		libwebsockets_get_random(context, &num_1, sizeof(int));
		libwebsockets_get_random(context, &num_2, sizeof(int));

		num_1 = (num_1 % max_1);
		num_2 = (num_2 % max_2);

		challenge[0] = num_1 >> 24;
		challenge[1] = num_1 >> 16;
		challenge[2] = num_1 >> 8;
		challenge[3] = num_1;
		challenge[4] = num_2 >> 24;
		challenge[5] = num_2 >> 16;
		challenge[6] = num_2 >> 8;
		challenge[7] = num_2;

		product_1 = num_1 * spaces_1;
		product_2 = num_2 * spaces_2;

		sprintf(key_1, "%lu", product_1);
		sprintf(key_2, "%lu", product_2);

		libwebsockets_get_random(context, &seed, sizeof(int));
		libwebsockets_get_random(context, &count, sizeof(int));

		libwebsockets_00_spam(key_1, (count % 12) + 1, seed);

		libwebsockets_get_random(context, &seed, sizeof(int));
		libwebsockets_get_random(context, &count, sizeof(int));

		libwebsockets_00_spam(key_2, (count % 12) + 1, seed);

		libwebsockets_get_random(context, &seed, sizeof(int));

		libwebsockets_00_spaceout(key_1, spaces_1, seed);
		libwebsockets_00_spaceout(key_2, spaces_2, seed >> 16);

		p += sprintf(p, "Upgrade: WebSocket\x0d\x0a"
			"Connection: Upgrade\x0d\x0aHost: %s\x0d\x0a",
			wsi->c_host);
		if (wsi->c_origin)
			p += sprintf(p, "Origin: %s\x0d\x0a", wsi->c_origin);

		if (wsi->c_protocol)
			p += sprintf(p, "Sec-WebSocket-Protocol: %s"
					 "\x0d\x0a", wsi->c_protocol);

		p += sprintf(p, "Sec-WebSocket-Key1: %s\x0d\x0a", key_1);
		p += sprintf(p, "Sec-WebSocket-Key2: %s\x0d\x0a", key_2);

		/* give userland a chance to append, eg, cookies */

		context->protocols[0].callback(context, wsi,
			LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER,
				NULL, &p, (pkt + sizeof(pkt)) - p - 12);

		p += sprintf(p, "\x0d\x0a");

		if (libwebsockets_get_random(context, p, 8) != 8)
			return NULL;
		memcpy(&challenge[8], p, 8);
		p += 8;

		/* precompute what we want to see from the server */

		MD5((unsigned char *)challenge, 16,
		   (unsigned char *)wsi->initial_handshake_hash_base64);

		goto issue_hdr;
	}

	p += sprintf(p, "Host: %s\x0d\x0a", wsi->c_host);
	p += sprintf(p, "Upgrade: websocket\x0d\x0a"
					"Connection: Upgrade\x0d\x0a"
					"Sec-WebSocket-Key: ");
	strcpy(p, wsi->key_b64);
	p += strlen(wsi->key_b64);
	p += sprintf(p, "\x0d\x0a");
	if (wsi->c_origin) {
        if (wsi->ietf_spec_revision == 13) {
            p += sprintf(p, "Origin: %s\x0d\x0a",
							 wsi->c_origin);
        }
        else {
		    p += sprintf(p, "Sec-WebSocket-Origin: %s\x0d\x0a",
							 wsi->c_origin);
        }
    }
	if (wsi->c_protocol)
		p += sprintf(p, "Sec-WebSocket-Protocol: %s\x0d\x0a",
						       wsi->c_protocol);

	/* tell the server what extensions we could support */

	p += sprintf(p, "Sec-WebSocket-Extensions: ");

	ext = context->extensions;
	while (ext && ext->callback) {

		n = 0;
		ext1 = context->extensions;

		while (ext1 && ext1->callback) {
			n |= ext1->callback(context, ext1, wsi,
				LWS_EXT_CALLBACK_CHECK_OK_TO_PROPOSE_EXTENSION,
					NULL, (char *)ext->name, 0);

			ext1++;
		}

		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++;
	}

	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(pkt)) - p - 12);

	p += sprintf(p, "\x0d\x0a");

	/* prepare the expected server accept response */

	strcpy((char *)buf, wsi->key_b64);
	strcpy((char *)&buf[strlen((char *)buf)], magic_websocket_guid);

	SHA1(buf, strlen((char *)buf), (unsigned char *)hash);

	lws_b64_encode_string(hash, 20,
			wsi->initial_handshake_hash_base64,
			     sizeof wsi->initial_handshake_hash_base64);

issue_hdr:

#if 0
	puts(pkt);
#endif

	/* done with these now */

	free(wsi->c_path);
	free(wsi->c_host);
	if (wsi->c_origin)
		free(wsi->c_origin);

	return p;
}