lib/client-parser.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"

int libwebsocket_client_rx_sm(struct libwebsocket *wsi, unsigned char c)
{
	int callback_action = LWS_CALLBACK_CLIENT_RECEIVE;
	int handled;
	struct lws_tokens eff_buf;
#ifndef LWS_NO_EXTENSIONS
	int n;
	int m;
#endif

	switch (wsi->lws_rx_parse_state) {
	case LWS_RXPS_NEW:

		switch (wsi->ietf_spec_revision) {

		case 13:
			wsi->u.ws.opcode = c & 0xf;
			wsi->u.ws.rsv = (c & 0x70);
			wsi->u.ws.final = !!((c >> 7) & 1);
			switch (wsi->u.ws.opcode) {
			case LWS_WS_OPCODE_07__TEXT_FRAME:
			case LWS_WS_OPCODE_07__BINARY_FRAME:
				wsi->u.ws.frame_is_binary = wsi->u.ws.opcode ==
						 LWS_WS_OPCODE_07__BINARY_FRAME;
				break;
			}
			wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN;
			break;

		default:
			lwsl_err("unknown spec version %02d\n",
						       wsi->ietf_spec_revision);
			break;
		}
		break;


	case LWS_RXPS_04_FRAME_HDR_LEN:

		wsi->u.ws.this_frame_masked = !!(c & 0x80);

		switch (c & 0x7f) {
		case 126:
			/* control frames are not allowed to have big lengths */
			if (wsi->u.ws.opcode & 8)
				goto illegal_ctl_length;
			wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN16_2;
			break;
		case 127:
			/* control frames are not allowed to have big lengths */
			if (wsi->u.ws.opcode & 8)
				goto illegal_ctl_length;
			wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_8;
			break;
		default:
			wsi->u.ws.rx_packet_length = c;
			if (wsi->u.ws.this_frame_masked)
				wsi->lws_rx_parse_state =
						LWS_RXPS_07_COLLECT_FRAME_KEY_1;
			else {
				if (c)
					wsi->lws_rx_parse_state =
					LWS_RXPS_PAYLOAD_UNTIL_LENGTH_EXHAUSTED;
				else {
					wsi->lws_rx_parse_state = LWS_RXPS_NEW;
					goto spill;
				}
			}
			break;
		}
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN16_2:
		wsi->u.ws.rx_packet_length = c << 8;
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN16_1;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN16_1:
		wsi->u.ws.rx_packet_length |= c;
		if (wsi->u.ws.this_frame_masked)
			wsi->lws_rx_parse_state =
					LWS_RXPS_07_COLLECT_FRAME_KEY_1;
		else {
			if (wsi->u.ws.rx_packet_length)
				wsi->lws_rx_parse_state =
					LWS_RXPS_PAYLOAD_UNTIL_LENGTH_EXHAUSTED;
			else {
				wsi->lws_rx_parse_state = LWS_RXPS_NEW;
				goto spill;
			}
		}
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_8:
		if (c & 0x80) {
			lwsl_warn("b63 of length must be zero\n");
			/* kill the connection */
			return -1;
		}
#if defined __LP64__
		wsi->u.ws.rx_packet_length = ((size_t)c) << 56;
#else
		wsi->u.ws.rx_packet_length = 0;
#endif
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_7;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_7:
#if defined __LP64__
		wsi->u.ws.rx_packet_length |= ((size_t)c) << 48;
#endif
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_6;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_6:
#if defined __LP64__
		wsi->u.ws.rx_packet_length |= ((size_t)c) << 40;
#endif
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_5;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_5:
#if defined __LP64__
		wsi->u.ws.rx_packet_length |= ((size_t)c) << 32;
#endif
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_4;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_4:
		wsi->u.ws.rx_packet_length |= ((size_t)c) << 24;
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_3;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_3:
		wsi->u.ws.rx_packet_length |= ((size_t)c) << 16;
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_2;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_2:
		wsi->u.ws.rx_packet_length |= ((size_t)c) << 8;
		wsi->lws_rx_parse_state = LWS_RXPS_04_FRAME_HDR_LEN64_1;
		break;

	case LWS_RXPS_04_FRAME_HDR_LEN64_1:
		wsi->u.ws.rx_packet_length |= (size_t)c;
		if (wsi->u.ws.this_frame_masked)
			wsi->lws_rx_parse_state =
					LWS_RXPS_07_COLLECT_FRAME_KEY_1;
		else {
			if (wsi->u.ws.rx_packet_length)
				wsi->lws_rx_parse_state =
					LWS_RXPS_PAYLOAD_UNTIL_LENGTH_EXHAUSTED;
			else {
				wsi->lws_rx_parse_state = LWS_RXPS_NEW;
				goto spill;
			}
		}
		break;

	case LWS_RXPS_07_COLLECT_FRAME_KEY_1:
		wsi->u.ws.frame_masking_nonce_04[0] = c;
		if (c)
			wsi->u.ws.all_zero_nonce = 0;
		wsi->lws_rx_parse_state = LWS_RXPS_07_COLLECT_FRAME_KEY_2;
		break;

	case LWS_RXPS_07_COLLECT_FRAME_KEY_2:
		wsi->u.ws.frame_masking_nonce_04[1] = c;
		if (c)
			wsi->u.ws.all_zero_nonce = 0;
		wsi->lws_rx_parse_state = LWS_RXPS_07_COLLECT_FRAME_KEY_3;
		break;

	case LWS_RXPS_07_COLLECT_FRAME_KEY_3:
		wsi->u.ws.frame_masking_nonce_04[2] = c;
		if (c)
			wsi->u.ws.all_zero_nonce = 0;
		wsi->lws_rx_parse_state = LWS_RXPS_07_COLLECT_FRAME_KEY_4;
		break;

	case LWS_RXPS_07_COLLECT_FRAME_KEY_4:
		wsi->u.ws.frame_masking_nonce_04[3] = c;
		if (c)
			wsi->u.ws.all_zero_nonce = 0;

		if (wsi->u.ws.rx_packet_length)
			wsi->lws_rx_parse_state =
					LWS_RXPS_PAYLOAD_UNTIL_LENGTH_EXHAUSTED;
		else {
			wsi->lws_rx_parse_state = LWS_RXPS_NEW;
			goto spill;
		}
		break;

	case LWS_RXPS_PAYLOAD_UNTIL_LENGTH_EXHAUSTED:

		if (!wsi->u.ws.rx_user_buffer)
			lwsl_err("NULL client rx_user_buffer\n");

		if ((!wsi->u.ws.this_frame_masked) || wsi->u.ws.all_zero_nonce)
			wsi->u.ws.rx_user_buffer[LWS_SEND_BUFFER_PRE_PADDING +
			       (wsi->u.ws.rx_user_buffer_head++)] = c;
		else
			wsi->u.ws.rx_user_buffer[LWS_SEND_BUFFER_PRE_PADDING +
			       (wsi->u.ws.rx_user_buffer_head++)] =
			c ^ wsi->u.ws.frame_masking_nonce_04[
					    (wsi->u.ws.frame_mask_index++) & 3];

		if (--wsi->u.ws.rx_packet_length == 0) {
			/* spill because we have the whole frame */
			wsi->lws_rx_parse_state = LWS_RXPS_NEW;
			goto spill;
		}

		/*
		 * if there's no protocol max frame size given, we are
		 * supposed to default to LWS_MAX_SOCKET_IO_BUF
		 */

		if (!wsi->protocol->rx_buffer_size &&
			 		wsi->u.ws.rx_user_buffer_head !=
			 				  LWS_MAX_SOCKET_IO_BUF)
			break;
		else
			if (wsi->protocol->rx_buffer_size &&
					wsi->u.ws.rx_user_buffer_head !=
						  wsi->protocol->rx_buffer_size)
			break;

		/* spill because we filled our rx buffer */
spill:

		handled = 0;

		/*
		 * is this frame a control packet we should take care of at this
		 * layer?  If so service it and hide it from the user callback
		 */

		switch (wsi->u.ws.opcode) {
		case LWS_WS_OPCODE_07__CLOSE:
			/* is this an acknowledgement of our close? */
			if (wsi->state == WSI_STATE_AWAITING_CLOSE_ACK) {
				/*
				 * fine he has told us he is closing too, let's
				 * finish our close
				 */
				lwsl_parser("seen server's close ack\n");
				return -1;
			}
			lwsl_parser("client sees server close len = %d\n",
						 wsi->u.ws.rx_user_buffer_head);
			/*
			 * parrot the close packet payload back
			 * we do not care about how it went, we are closing
			 * immediately afterwards
			 */
			libwebsocket_write(wsi, (unsigned char *)
			   &wsi->u.ws.rx_user_buffer[
				LWS_SEND_BUFFER_PRE_PADDING],
				wsi->u.ws.rx_user_buffer_head, LWS_WRITE_CLOSE);
			wsi->state = WSI_STATE_RETURNED_CLOSE_ALREADY;
			/* close the connection */
			return -1;

		case LWS_WS_OPCODE_07__PING:
			lwsl_info("client received ping, doing pong\n");
			/*
			 * parrot the ping packet payload back as a pong
			 * !!! this may block or have partial write or fail
			 * !!! very unlikely if the ping size is small
			 */
			libwebsocket_write(wsi, (unsigned char *)
			    &wsi->u.ws.rx_user_buffer[
				LWS_SEND_BUFFER_PRE_PADDING],
					wsi->u.ws.rx_user_buffer_head,
								LWS_WRITE_PONG);
			handled = 1;
			break;

		case LWS_WS_OPCODE_07__PONG:
			lwsl_info("client receied pong\n");
			lwsl_hexdump(&wsi->u.ws.rx_user_buffer[
				LWS_SEND_BUFFER_PRE_PADDING],
				    wsi->u.ws.rx_user_buffer_head);

			/* issue it */
			callback_action = LWS_CALLBACK_CLIENT_RECEIVE_PONG;
			break;

		case LWS_WS_OPCODE_07__CONTINUATION:
		case LWS_WS_OPCODE_07__TEXT_FRAME:
		case LWS_WS_OPCODE_07__BINARY_FRAME:
			break;

		default:

			lwsl_parser("Reserved opc 0x%2X\n", wsi->u.ws.opcode);
#ifndef LWS_NO_EXTENSIONS
			/*
			 * It's something special we can't understand here.
			 * Pass the payload up to the extension's parsing
			 * state machine.
			 */

			eff_buf.token = &wsi->u.ws.rx_user_buffer[
						   LWS_SEND_BUFFER_PRE_PADDING];
			eff_buf.token_len = wsi->u.ws.rx_user_buffer_head;

			for (n = 0; n < wsi->count_active_extensions; n++) {
				m = wsi->active_extensions[n]->callback(
					wsi->protocol->owning_server,
					wsi->active_extensions[n], wsi,
					LWS_EXT_CALLBACK_EXTENDED_PAYLOAD_RX,
					    wsi->active_extensions_user[n],
								   &eff_buf, 0);
				if (m)
					handled = 1;
			}

			if (!handled) {
#else
			{
#endif
				lwsl_ext("Unhandled ext opc 0x%x\n",
							      wsi->u.ws.opcode);
				wsi->u.ws.rx_user_buffer_head = 0;

				return 0;
			}

			break;
		}

		/*
		 * No it's real payload, pass it up to the user callback.
		 * It's nicely buffered with the pre-padding taken care of
		 * so it can be sent straight out again using libwebsocket_write
		 */
		if (handled)
			goto already_done;

		eff_buf.token = &wsi->u.ws.rx_user_buffer[
						LWS_SEND_BUFFER_PRE_PADDING];
		eff_buf.token_len = wsi->u.ws.rx_user_buffer_head;
#ifndef LWS_NO_EXTENSIONS
		for (n = 0; n < wsi->count_active_extensions; n++) {
			m = wsi->active_extensions[n]->callback(
				wsi->protocol->owning_server,
				wsi->active_extensions[n], wsi,
				LWS_EXT_CALLBACK_PAYLOAD_RX,
				wsi->active_extensions_user[n],
				&eff_buf, 0);
			if (m < 0) {
				lwsl_ext(
					"Ext '%s' failed to handle payload!\n",
					       wsi->active_extensions[n]->name);
				return -1;
			}
		}
#endif
		if (eff_buf.token_len <= 0)
			goto already_done;

		eff_buf.token[eff_buf.token_len] = '\0';

		if (!wsi->protocol->callback)
			goto already_done;

		if (callback_action == LWS_CALLBACK_CLIENT_RECEIVE_PONG)
			lwsl_info("Client doing pong callback\n");

		wsi->protocol->callback(
			wsi->protocol->owning_server,
			wsi,
			(enum libwebsocket_callback_reasons)callback_action,
			wsi->user_space,
			eff_buf.token,
			eff_buf.token_len);

already_done:
		wsi->u.ws.rx_user_buffer_head = 0;
		break;
	default:
		lwsl_err("client rx illegal state\n");
		return 1;
	}

	return 0;

illegal_ctl_length:

	lwsl_warn("Control frame asking for extended length is illegal\n");
	/* kill the connection */
	return -1;

}