lib/output.c

/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010-2015 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
lws_0405_frame_mask_generate(struct lws *wsi)
{
#if 0
	wsi->u.ws.mask[0] = 0;
	wsi->u.ws.mask[1] = 0;
	wsi->u.ws.mask[2] = 0;
	wsi->u.ws.mask[3] = 0;
#else
	int n;
	/* fetch the per-frame nonce */

	n = lws_get_random(lws_get_context(wsi), wsi->u.ws.mask, 4);
	if (n != 4) {
		lwsl_parser("Unable to read from random device %s %d\n",
			    SYSTEM_RANDOM_FILEPATH, n);
		return 1;
	}
#endif
	/* start masking from first byte of masking key buffer */
	wsi->u.ws.mask_idx = 0;

	return 0;
}

#ifdef _DEBUG

LWS_VISIBLE void lwsl_hexdump(void *vbuf, size_t len)
{
	unsigned char *buf = (unsigned char *)vbuf;
	unsigned int n, m, start;
	char line[80];
	char *p;

	lwsl_parser("\n");

	for (n = 0; n < len;) {
		start = n;
		p = line;

		p += sprintf(p, "%04X: ", start);

		for (m = 0; m < 16 && n < len; m++)
			p += sprintf(p, "%02X ", buf[n++]);
		while (m++ < 16)
			p += sprintf(p, "   ");

		p += sprintf(p, "   ");

		for (m = 0; m < 16 && (start + m) < len; m++) {
			if (buf[start + m] >= ' ' && buf[start + m] < 127)
				*p++ = buf[start + m];
			else
				*p++ = '.';
		}
		while (m++ < 16)
			*p++ = ' ';

		*p++ = '\n';
		*p = '\0';
		lwsl_debug("%s", line);
	}
	lwsl_debug("\n");
}

#endif

/*
 * notice this returns number of bytes consumed, or -1
 */

int lws_issue_raw(struct lws *wsi, unsigned char *buf, size_t len)
{
	struct lws_context *context = lws_get_context(wsi);
	size_t real_len = len;
	int n, m;

	if (!len)
		return 0;
	/* just ignore sends after we cleared the truncation buffer */
	if (wsi->state == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE &&
	    !wsi->trunc_len)
		return len;

	if (wsi->trunc_len && (buf < wsi->trunc_alloc ||
	    buf > (wsi->trunc_alloc + wsi->trunc_len +
		   wsi->trunc_offset))) {
		lwsl_err("****** %x Sending new, pending truncated ...\n", wsi);
		assert(0);
	}

	m = lws_ext_cb_active(wsi, LWS_EXT_CB_PACKET_TX_DO_SEND, &buf, len);
	if (m < 0)
		return -1;
	if (m) /* handled */ {
		n = m;
		goto handle_truncated_send;
	}

	if (!lws_socket_is_valid(wsi->sock))
		lwsl_warn("** error invalid sock but expected to send\n");

	/* nope, send it on the socket directly */
	lws_latency_pre(context, wsi);
	n = lws_ssl_capable_write(wsi, buf, len);
	lws_latency(context, wsi, "send lws_issue_raw", n,
		    (unsigned int)n == len);

	switch (n) {
	case LWS_SSL_CAPABLE_ERROR:
		/* we're going to close, let close know sends aren't possible */
		wsi->socket_is_permanently_unusable = 1;
		return -1;
	case LWS_SSL_CAPABLE_MORE_SERVICE:
		/* nothing got sent, not fatal, retry the whole thing later */
		n = 0;
		break;
	}

handle_truncated_send:
	/*
	 * we were already handling a truncated send?
	 */
	if (wsi->trunc_len) {
		lwsl_info("%p partial adv %d (vs %d)\n", wsi, n, real_len);
		wsi->trunc_offset += n;
		wsi->trunc_len -= n;

		if (!wsi->trunc_len) {
			lwsl_info("***** %x partial send completed\n", wsi);
			/* done with it, but don't free it */
			n = real_len;
			if (wsi->state == LWSS_FLUSHING_STORED_SEND_BEFORE_CLOSE) {
				lwsl_info("***** %x signalling to close now\n", wsi);
				return -1; /* retry closing now */
			}
		}
		/* always callback on writeable */
		lws_callback_on_writable(wsi);

		return n;
	}

	if ((unsigned int)n == real_len)
		/* what we just sent went out cleanly */
		return n;

	/*
	 * Newly truncated send.  Buffer the remainder (it will get
	 * first priority next time the socket is writable)
	 */
	lwsl_info("%p new partial sent %d from %d total\n", wsi, n, real_len);

	/*
	 *  - if we still have a suitable malloc lying around, use it
	 *  - or, if too small, reallocate it
	 *  - or, if no buffer, create it
	 */
	if (!wsi->trunc_alloc || real_len - n > wsi->trunc_alloc_len) {
		lws_free(wsi->trunc_alloc);

		wsi->trunc_alloc_len = real_len - n;
		wsi->trunc_alloc = lws_malloc(real_len - n);
		if (!wsi->trunc_alloc) {
			lwsl_err("truncated send: unable to malloc %d\n",
				 real_len - n);
			return -1;
		}
	}
	wsi->trunc_offset = 0;
	wsi->trunc_len = real_len - n;
	memcpy(wsi->trunc_alloc, buf + n, real_len - n);

	/* since something buffered, force it to get another chance to send */
	lws_callback_on_writable(wsi);

	return real_len;
}

/**
 * lws_write() - Apply protocol then write data to client
 * @wsi:	Websocket instance (available from user callback)
 * @buf:	The data to send.  For data being sent on a websocket
 *		connection (ie, not default http), this buffer MUST have
 *		LWS_PRE bytes valid BEFORE the pointer.
 *		This is so the protocol header data can be added in-situ.
 * @len:	Count of the data bytes in the payload starting from buf
 * @protocol:	Use LWS_WRITE_HTTP to reply to an http connection, and one
 *		of LWS_WRITE_BINARY or LWS_WRITE_TEXT to send appropriate
 *		data on a websockets connection.  Remember to allow the extra
 *		bytes before and after buf if LWS_WRITE_BINARY or LWS_WRITE_TEXT
 *		are used.
 *
 *	This function provides the way to issue data back to the client
 *	for both http and websocket protocols.
 *
 *	In the case of sending using websocket protocol, be sure to allocate
 *	valid storage before and after buf as explained above.  This scheme
 *	allows maximum efficiency of sending data and protocol in a single
 *	packet while not burdening the user code with any protocol knowledge.
 *
 *	Return may be -1 for a fatal error needing connection close, or a
 *	positive number reflecting the amount of bytes actually sent.  This
 *	can be less than the requested number of bytes due to OS memory
 *	pressure at any given time.
 */

LWS_VISIBLE int lws_write(struct lws *wsi, unsigned char *buf, size_t len,
			  enum lws_write_protocol wp)
{
	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
	int masked7 = (wsi->mode == LWSCM_WS_CLIENT);
	unsigned char is_masked_bit = 0;
	unsigned char *dropmask = NULL;
	struct lws_tokens eff_buf;
	int pre = 0, n;
	size_t orig_len = len;

	if (wsi->state == LWSS_ESTABLISHED && wsi->u.ws.tx_draining_ext) {
		/* remove us from the list */
		struct lws **w = &pt->tx_draining_ext_list;
		lwsl_debug("%s: TX EXT DRAINING: Remove from list\n", __func__);
		wsi->u.ws.tx_draining_ext = 0;
		/* remove us from context draining ext list */
		while (*w) {
			if (*w == wsi) {
				*w = wsi->u.ws.tx_draining_ext_list;
				break;
			}
			w = &((*w)->u.ws.tx_draining_ext_list);
		}
		wsi->u.ws.tx_draining_ext_list = NULL;
		wp = (wsi->u.ws.tx_draining_stashed_wp & 0xc0) |
				LWS_WRITE_CONTINUATION;

		lwsl_ext("FORCED draining wp to 0x%02X\n", wp);
	}

	if (wp == LWS_WRITE_HTTP ||
	    wp == LWS_WRITE_HTTP_FINAL ||
	    wp == LWS_WRITE_HTTP_HEADERS)
		goto send_raw;

	/* if not in a state to send stuff, then just send nothing */

	if (wsi->state != LWSS_ESTABLISHED &&
	    ((wsi->state != LWSS_RETURNED_CLOSE_ALREADY &&
	      wsi->state != LWSS_AWAITING_CLOSE_ACK) ||
			    wp != LWS_WRITE_CLOSE))
		return 0;

	/* if we are continuing a frame that already had its header done */

	if (wsi->u.ws.inside_frame) {
		lwsl_debug("INSIDE FRAME\n");
		goto do_more_inside_frame;
	}

	wsi->u.ws.clean_buffer = 1;

	/*
	 * give a chance to the extensions to modify payload
	 * the extension may decide to produce unlimited payload erratically
	 * (eg, compression extension), so we require only that if he produces
	 * something, it will be a complete fragment of the length known at
	 * the time (just the fragment length known), and if he has
	 * more we will come back next time he is writeable and allow him to
	 * produce more fragments until he's drained.
	 *
	 * This allows what is sent each time it is writeable to be limited to
	 * a size that can be sent without partial sends or blocking, allows
	 * interleaving of control frames and other connection service.
	 */
	eff_buf.token = (char *)buf;
	eff_buf.token_len = len;

	switch ((int)wp) {
	case LWS_WRITE_PING:
	case LWS_WRITE_PONG:
	case LWS_WRITE_CLOSE:
		break;
	default:
		n = lws_ext_cb_active(wsi, LWS_EXT_CB_PAYLOAD_TX, &eff_buf, wp);
		if (n < 0)
			return -1;

		if (n && eff_buf.token_len) {
			/* extension requires further draining */
			wsi->u.ws.tx_draining_ext = 1;
			wsi->u.ws.tx_draining_ext_list = pt->tx_draining_ext_list;
			pt->tx_draining_ext_list = wsi;
			/* we must come back to do more */
			lws_callback_on_writable(wsi);
			/*
			 * keep a copy of the write type for the overall
			 * action that has provoked generation of these
			 * fragments, so the last guy can use its FIN state.
			 */
			wsi->u.ws.tx_draining_stashed_wp = wp;
			/* this is definitely not actually the last fragment
			 * because the extension asserted he has more coming
			 * So make sure this intermediate one doesn't go out
			 * with a FIN.
			 */
			wp |= LWS_WRITE_NO_FIN;
		}

		if (eff_buf.token_len && wsi->u.ws.stashed_write_pending) {
			wsi->u.ws.stashed_write_pending = 0;
			wp = (wp &0xc0) | (int)wsi->u.ws.stashed_write_type;
		}
	}

	/*
	 * an extension did something we need to keep... for example, if
	 * compression extension, it has already updated its state according
	 * to this being issued
	 */
	if ((char *)buf != eff_buf.token) {
		/*
		 * ext might eat it, but no have anything to issue yet
		 * in that case we have to follow his lead, but stash and
		 * replace the write type that was lost here the first time.
		 */
		if (len && !eff_buf.token_len) {
			if (!wsi->u.ws.stashed_write_pending)
				wsi->u.ws.stashed_write_type = (char)wp & 0x3f;
			wsi->u.ws.stashed_write_pending = 1;
			return len;
		}
		/*
		 * extension recreated it:
		 * need to buffer this if not all sent
		 */
		wsi->u.ws.clean_buffer = 0;
	}

	buf = (unsigned char *)eff_buf.token;
	len = eff_buf.token_len;

	switch (wsi->ietf_spec_revision) {
	case 13:
		if (masked7) {
			pre += 4;
			dropmask = &buf[0 - pre];
			is_masked_bit = 0x80;
		}

		switch (wp & 0xf) {
		case LWS_WRITE_TEXT:
			n = LWSWSOPC_TEXT_FRAME;
			break;
		case LWS_WRITE_BINARY:
			n = LWSWSOPC_BINARY_FRAME;
			break;
		case LWS_WRITE_CONTINUATION:
			n = LWSWSOPC_CONTINUATION;
			break;

		case LWS_WRITE_CLOSE:
			n = LWSWSOPC_CLOSE;
			break;
		case LWS_WRITE_PING:
			n = LWSWSOPC_PING;
			break;
		case LWS_WRITE_PONG:
			n = LWSWSOPC_PONG;
			break;
		default:
			lwsl_warn("lws_write: unknown write opc / wp\n");
			return -1;
		}

		if (!(wp & LWS_WRITE_NO_FIN))
			n |= 1 << 7;

		if (len < 126) {
			pre += 2;
			buf[-pre] = n;
			buf[-pre + 1] = (unsigned char)(len | is_masked_bit);
		} else {
			if (len < 65536) {
				pre += 4;
				buf[-pre] = n;
				buf[-pre + 1] = 126 | is_masked_bit;
				buf[-pre + 2] = (unsigned char)(len >> 8);
				buf[-pre + 3] = (unsigned char)len;
			} else {
				pre += 10;
				buf[-pre] = n;
				buf[-pre + 1] = 127 | is_masked_bit;
#if defined __LP64__
					buf[-pre + 2] = (len >> 56) & 0x7f;
					buf[-pre + 3] = len >> 48;
					buf[-pre + 4] = len >> 40;
					buf[-pre + 5] = len >> 32;
#else
					buf[-pre + 2] = 0;
					buf[-pre + 3] = 0;
					buf[-pre + 4] = 0;
					buf[-pre + 5] = 0;
#endif
				buf[-pre + 6] = (unsigned char)(len >> 24);
				buf[-pre + 7] = (unsigned char)(len >> 16);
				buf[-pre + 8] = (unsigned char)(len >> 8);
				buf[-pre + 9] = (unsigned char)len;
			}
		}
		break;
	}

do_more_inside_frame:

	/*
	 * Deal with masking if we are in client -> server direction and
	 * the wp demands it
	 */

	if (masked7) {
		if (!wsi->u.ws.inside_frame)
			if (lws_0405_frame_mask_generate(wsi)) {
				lwsl_err("frame mask generation failed\n");
				return -1;
			}

		/*
		 * in v7, just mask the payload
		 */
		if (dropmask) { /* never set if already inside frame */
			for (n = 4; n < (int)len + 4; n++)
				dropmask[n] = dropmask[n] ^ wsi->u.ws.mask[
					(wsi->u.ws.mask_idx++) & 3];

			/* copy the frame nonce into place */
			memcpy(dropmask, wsi->u.ws.mask, 4);
		}
	}

send_raw:
	switch ((int)wp) {
	case LWS_WRITE_CLOSE:
/*		lwsl_hexdump(&buf[-pre], len); */
	case LWS_WRITE_HTTP:
	case LWS_WRITE_HTTP_FINAL:
	case LWS_WRITE_HTTP_HEADERS:
	case LWS_WRITE_PONG:
	case LWS_WRITE_PING:
#ifdef LWS_USE_HTTP2
		if (wsi->mode == LWSCM_HTTP2_SERVING) {
			unsigned char flags = 0;

			n = LWS_HTTP2_FRAME_TYPE_DATA;
			if (wp == LWS_WRITE_HTTP_HEADERS) {
				n = LWS_HTTP2_FRAME_TYPE_HEADERS;
				flags = LWS_HTTP2_FLAG_END_HEADERS;
				if (wsi->u.http2.send_END_STREAM)
					flags |= LWS_HTTP2_FLAG_END_STREAM;
			}

			if ((wp == LWS_WRITE_HTTP ||
			     wp == LWS_WRITE_HTTP_FINAL) &&
			    wsi->u.http.content_length) {
				wsi->u.http.content_remain -= len;
				lwsl_info("%s: content_remain = %lu\n", __func__,
					  wsi->u.http.content_remain);
				if (!wsi->u.http.content_remain) {
					lwsl_info("%s: selecting final write mode\n", __func__);
					wp = LWS_WRITE_HTTP_FINAL;
				}
			}

			if (wp == LWS_WRITE_HTTP_FINAL && wsi->u.http2.END_STREAM) {
				lwsl_info("%s: setting END_STREAM\n", __func__);
				flags |= LWS_HTTP2_FLAG_END_STREAM;
			}

			return lws_http2_frame_write(wsi, n, flags,
					wsi->u.http2.my_stream_id, len, buf);
		}
#endif
		return lws_issue_raw(wsi, (unsigned char *)buf - pre, len + pre);
	default:
		break;
	}

	/*
	 * give any active extensions a chance to munge the buffer
	 * before send.  We pass in a pointer to an lws_tokens struct
	 * prepared with the default buffer and content length that's in
	 * there.  Rather than rewrite the default buffer, extensions
	 * that expect to grow the buffer can adapt .token to
	 * point to their own per-connection buffer in the extension
	 * user allocation.  By default with no extensions or no
	 * extension callback handling, just the normal input buffer is
	 * used then so it is efficient.
	 *
	 * callback returns 1 in case it wants to spill more buffers
	 *
	 * This takes care of holding the buffer if send is incomplete, ie,
	 * if wsi->u.ws.clean_buffer is 0 (meaning an extension meddled with
	 * the buffer).  If wsi->u.ws.clean_buffer is 1, it will instead
	 * return to the user code how much OF THE USER BUFFER was consumed.
	 */

	n = lws_issue_raw_ext_access(wsi, buf - pre, len + pre);
	wsi->u.ws.inside_frame = 1;
	if (n <= 0)
		return n;

	if (n == (int)len + pre) {
		/* everything in the buffer was handled (or rebuffered...) */
		wsi->u.ws.inside_frame = 0;
		return orig_len;
	}

	/*
	 * it is how many bytes of user buffer got sent... may be < orig_len
	 * in which case callback when writable has already been arranged
	 * and user code can call lws_write() again with the rest
	 * later.
	 */

	return n - pre;
}

LWS_VISIBLE int lws_serve_http_file_fragment(struct lws *wsi)
{
	struct lws_context *context = wsi->context;
	struct lws_context_per_thread *pt = &context->pt[(int)wsi->tsi];
	unsigned long amount;
	int n, m;

	while (!lws_send_pipe_choked(wsi)) {
		if (wsi->trunc_len) {
			if (lws_issue_raw(wsi, wsi->trunc_alloc +
					  wsi->trunc_offset,
					  wsi->trunc_len) < 0) {
				lwsl_info("%s: closing\n", __func__);
				return -1;
			}
			continue;
		}

		if (wsi->u.http.filepos == wsi->u.http.filelen)
			goto all_sent;

		if (lws_plat_file_read(wsi, wsi->u.http.fd, &amount,
				       pt->serv_buf,
				       LWS_MAX_SOCKET_IO_BUF) < 0)
			return -1; /* caller will close */

		n = (int)amount;
		if (n) {
			lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
					context->timeout_secs);
			wsi->u.http.filepos += n;
			m = lws_write(wsi, pt->serv_buf, n,
				      wsi->u.http.filepos == wsi->u.http.filelen ?
					LWS_WRITE_HTTP_FINAL : LWS_WRITE_HTTP);
			if (m < 0)
				return -1;

			if (m != n)
				/* adjust for what was not sent */
				if (lws_plat_file_seek_cur(wsi, wsi->u.http.fd,
							   m - n) ==
							     (unsigned long)-1)
					return -1;
		}
all_sent:
		if (!wsi->trunc_len && wsi->u.http.filepos == wsi->u.http.filelen) {
			wsi->state = LWSS_HTTP;

			/* we might be in keepalive, so close it off here */
			lws_plat_file_close(wsi, wsi->u.http.fd);
			wsi->u.http.fd = LWS_INVALID_FILE;

			if (wsi->protocol->callback)
				/* ignore callback returned value */
				if (user_callback_handle_rxflow(
				     wsi->protocol->callback, wsi,
				     LWS_CALLBACK_HTTP_FILE_COMPLETION,
				     wsi->user_space, NULL, 0) < 0)
					return -1;
			return 1;  /* >0 indicates completed */
		}
	}

	lwsl_info("choked before able to send whole file (post)\n");
	lws_callback_on_writable(wsi);

	return 0; /* indicates further processing must be done */
}

#if LWS_POSIX
LWS_VISIBLE int
lws_ssl_capable_read_no_ssl(struct lws *wsi, unsigned char *buf, int len)
{
	int n;

	n = recv(wsi->sock, (char *)buf, len, 0);
	if (n >= 0)
		return n;
#if LWS_POSIX
	if (LWS_ERRNO == LWS_EAGAIN ||
	    LWS_ERRNO == LWS_EWOULDBLOCK ||
	    LWS_ERRNO == LWS_EINTR)
		return LWS_SSL_CAPABLE_MORE_SERVICE;
#endif
	lwsl_warn("error on reading from skt\n");
	return LWS_SSL_CAPABLE_ERROR;
}

LWS_VISIBLE int
lws_ssl_capable_write_no_ssl(struct lws *wsi, unsigned char *buf, int len)
{
	int n = 0;

#if LWS_POSIX
	n = send(wsi->sock, (char *)buf, len, MSG_NOSIGNAL);
//	lwsl_info("%s: sent len %d result %d", __func__, len, n);
	if (n >= 0)
		return n;

	if (LWS_ERRNO == LWS_EAGAIN ||
	    LWS_ERRNO == LWS_EWOULDBLOCK ||
	    LWS_ERRNO == LWS_EINTR) {
		if (LWS_ERRNO == LWS_EWOULDBLOCK)
			lws_set_blocking_send(wsi);

		return LWS_SSL_CAPABLE_MORE_SERVICE;
	}
#else
	(void)n;
	(void)wsi;
	(void)buf;
	(void)len;
	// !!!
#endif

	lwsl_debug("ERROR writing len %d to skt fd %d err %d / errno %d\n", len, wsi->sock, n, LWS_ERRNO);
	return LWS_SSL_CAPABLE_ERROR;
}
#endif
LWS_VISIBLE int
lws_ssl_pending_no_ssl(struct lws *wsi)
{
	(void)wsi;
	return 0;
}