server.c

	 * that is already at least the start of another header set, simply
	 * reset the existing header table and keep it.
	 */
	if (wsi->http.ah) {
		// lws_buflist_describe(&wsi->buflist, wsi);
		if (!lws_buflist_next_segment_len(&wsi->buflist, NULL)) {
			lwsl_debug("%s: %p: nothing in buflist so detaching ah\n",
				  __func__, wsi);
			lws_header_table_detach(wsi, 1);
#ifdef LWS_WITH_TLS
			/*
			 * additionally... if we are hogging an SSL instance
			 * with no pending pipelined headers (or ah now), and
			 * SSL is scarce, drop this connection without waiting
			 */

			if (wsi->vhost->tls.use_ssl &&
			    wsi->context->simultaneous_ssl_restriction &&
			    wsi->context->simultaneous_ssl ==
				   wsi->context->simultaneous_ssl_restriction) {
				lwsl_info("%s: simultaneous_ssl_restriction\n",
					  __func__);
				return 1;
			}
#endif
		} else {
			lwsl_info("%s: %p: resetting and keeping ah as pipeline\n",
				  __func__, wsi);
			lws_header_table_reset(wsi, 0);
			/*
			 * If we kept the ah, we should restrict the amount
			 * of time we are willing to keep it.  Otherwise it
			 * will be bound the whole time the connection remains
			 * open.
			 */
			lws_set_timeout(wsi, PENDING_TIMEOUT_HOLDING_AH,
					wsi->vhost->keepalive_timeout);
		}
		/* If we're (re)starting on headers, need other implied init */
		if (wsi->http.ah)
			wsi->http.ah->ues = URIES_IDLE;

		//lwsi_set_state(wsi, LRS_ESTABLISHED); // !!!
	} else
		if (lws_buflist_next_segment_len(&wsi->buflist, NULL))
			if (lws_header_table_attach(wsi, 0))
				lwsl_debug("acquired ah\n");

	lwsl_debug("%s: %p: keep-alive await new transaction (state 0x%x)\n",
			__func__, wsi, wsi->wsistate);
	lws_callback_on_writable(wsi);

	return 0;
}


LWS_VISIBLE int
lws_serve_http_file(struct lws *wsi, const char *file, const char *content_type,
		    const char *other_headers, int other_headers_len)
{
	struct lws_context *context = lws_get_context(wsi);
	struct lws_context_per_thread *pt = &context->pt[(int)wsi->tsi];
#if defined(LWS_WITH_RANGES)
	struct lws_range_parsing *rp = &wsi->http.range;
#endif
	char cache_control[50], *cc = "no-store";
	unsigned char *response = pt->serv_buf + LWS_PRE;
	unsigned char *p = response;
	unsigned char *end = p + context->pt_serv_buf_size - LWS_PRE;
	lws_filepos_t total_content_length;
	int ret = 0, cclen = 8, n = HTTP_STATUS_OK;
	lws_fop_flags_t fflags = LWS_O_RDONLY;
#if defined(LWS_WITH_RANGES)
	int ranges;
#endif
	const struct lws_plat_file_ops *fops;
	const char *vpath;

	if (wsi->handling_404)
		n = HTTP_STATUS_NOT_FOUND;

	/*
	 * We either call the platform fops .open with first arg platform fops,
	 * or we call fops_zip .open with first arg platform fops, and fops_zip
	 * open will decide whether to switch to fops_zip or stay with fops_def.
	 *
	 * If wsi->http.fop_fd is already set, the caller already opened it
	 */
	if (!wsi->http.fop_fd) {
		fops = lws_vfs_select_fops(wsi->context->fops, file, &vpath);
		fflags |= lws_vfs_prepare_flags(wsi);
		wsi->http.fop_fd = fops->LWS_FOP_OPEN(wsi->context->fops,
							file, vpath, &fflags);
		if (!wsi->http.fop_fd) {
			lwsl_info("%s: Unable to open: '%s': errno %d\n",
				  __func__, file, errno);
			if (lws_return_http_status(wsi, HTTP_STATUS_NOT_FOUND, NULL))
						return -1;
			return !wsi->http2_substream;
		}
	}
	wsi->http.filelen = lws_vfs_get_length(wsi->http.fop_fd);
	total_content_length = wsi->http.filelen;

#if defined(LWS_WITH_RANGES)
	ranges = lws_ranges_init(wsi, rp, wsi->http.filelen);

	lwsl_debug("Range count %d\n", ranges);
	/*
	 * no ranges -> 200;
	 *  1 range  -> 206 + Content-Type: normal; Content-Range;
	 *  more     -> 206 + Content-Type: multipart/byteranges
	 *  		Repeat the true Content-Type in each multipart header
	 *  		along with Content-Range
	 */
	if (ranges < 0) {
		/* it means he expressed a range in Range:, but it was illegal */
		lws_return_http_status(wsi, HTTP_STATUS_REQ_RANGE_NOT_SATISFIABLE,
				       NULL);
		if (lws_http_transaction_completed(wsi))
			return -1; /* <0 means just hang up */

		lws_vfs_file_close(&wsi->http.fop_fd);

		return 0; /* == 0 means we dealt with the transaction complete */
	}
	if (ranges)
		n = HTTP_STATUS_PARTIAL_CONTENT;
#endif

	if (lws_add_http_header_status(wsi, n, &p, end))
		return -1;

	if ((wsi->http.fop_fd->flags & (LWS_FOP_FLAG_COMPR_ACCEPTABLE_GZIP |
		       LWS_FOP_FLAG_COMPR_IS_GZIP)) ==
	    (LWS_FOP_FLAG_COMPR_ACCEPTABLE_GZIP | LWS_FOP_FLAG_COMPR_IS_GZIP)) {
		if (lws_add_http_header_by_token(wsi,
			WSI_TOKEN_HTTP_CONTENT_ENCODING,
			(unsigned char *)"gzip", 4, &p, end))
			return -1;
		lwsl_info("file is being provided in gzip\n");
	}
#if defined(LWS_WITH_HTTP_STREAM_COMPRESSION)
	else {
		/*
		 * if we know its very compressible, and we can use
		 * compression, then use the most preferred compression
		 * method that the client said he will accept
		 */

		if (!strncmp(content_type, "text/", 5) ||
		    !strcmp(content_type, "application/javascript") ||
		    !strcmp(content_type, "image/svg+xml"))
			lws_http_compression_apply(wsi, NULL, &p, end, 0);
	}
#endif

	if (
#if defined(LWS_WITH_RANGES)
	    ranges < 2 &&
#endif
	    content_type && content_type[0])
		if (lws_add_http_header_by_token(wsi,
						 WSI_TOKEN_HTTP_CONTENT_TYPE,
						 (unsigned char *)content_type,
						 (int)strlen(content_type),
						 &p, end))
			return -1;

#if defined(LWS_WITH_RANGES)
	if (ranges >= 2) { /* multipart byteranges */
		lws_strncpy(wsi->http.multipart_content_type, content_type,
			sizeof(wsi->http.multipart_content_type));

		if (lws_add_http_header_by_token(wsi,
						 WSI_TOKEN_HTTP_CONTENT_TYPE,
						 (unsigned char *)
						 "multipart/byteranges; "
						 "boundary=_lws",
			 	 	 	 20, &p, end))
			return -1;

		/*
		 *  our overall content length has to include
		 *
		 *  - (n + 1) x "_lws\r\n"
		 *  - n x Content-Type: xxx/xxx\r\n
		 *  - n x Content-Range: bytes xxx-yyy/zzz\r\n
		 *  - n x /r/n
		 *  - the actual payloads (aggregated in rp->agg)
		 *
		 *  Precompute it for the main response header
		 */

		total_content_length = (lws_filepos_t)rp->agg +
				       6 /* final _lws\r\n */;

		lws_ranges_reset(rp);
		while (lws_ranges_next(rp)) {
			n = lws_snprintf(cache_control, sizeof(cache_control),
					"bytes %llu-%llu/%llu",
					rp->start, rp->end, rp->extent);

			total_content_length +=
				6 /* header _lws\r\n */ +
				/* Content-Type: xxx/xxx\r\n */
				14 + strlen(content_type) + 2 +
				/* Content-Range: xxxx\r\n */
				15 + n + 2 +
				2; /* /r/n */
		}

		lws_ranges_reset(rp);
		lws_ranges_next(rp);
	}

	if (ranges == 1) {
		total_content_length = (lws_filepos_t)rp->agg;
		n = lws_snprintf(cache_control, sizeof(cache_control),
				 "bytes %llu-%llu/%llu",
				 rp->start, rp->end, rp->extent);

		if (lws_add_http_header_by_token(wsi,
						 WSI_TOKEN_HTTP_CONTENT_RANGE,
						 (unsigned char *)cache_control,
						 n, &p, end))
			return -1;
	}

	wsi->http.range.inside = 0;

	if (lws_add_http_header_by_token(wsi, WSI_TOKEN_HTTP_ACCEPT_RANGES,
					 (unsigned char *)"bytes", 5, &p, end))
		return -1;
#endif

	if (!wsi->http2_substream) {
		/* for http/1.1 ... */
		if (!wsi->sending_chunked
#if defined(LWS_WITH_HTTP_STREAM_COMPRESSION)
				&& !wsi->http.lcs
#endif
		) {
			/* ... if not already using chunked and not using an
			 * http compression translation, then send the naive
			 * content length
			 */
			if (lws_add_http_header_content_length(wsi,
						total_content_length, &p, end))
				return -1;
		} else {

#if defined(LWS_WITH_HTTP_STREAM_COMPRESSION)
			if (wsi->http.lcs) {

				/* ...otherwise, for http 1 it must go chunked.
				 * For the compression case, the reason is we
				 * compress on the fly and do not know the
				 * compressed content-length until it has all
				 * been sent.  Http/1.1 pipelining must be able
				 * to know where the transaction boundaries are
				 * ... so chunking...
				 */
				if (lws_add_http_header_by_token(wsi,
						WSI_TOKEN_HTTP_TRANSFER_ENCODING,
						(unsigned char *)"chunked", 7,
						&p, end))
					return -1;

				/*
				 * ...this is fun, isn't it :-)  For h1 that is
				 * using an http compression translation, the
				 * compressor must chunk its output privately.
				 *
				 * h2 doesn't need (or support) any of this
				 * crap.
				 */
				lwsl_debug("setting chunking\n");
				wsi->http.comp_ctx.chunking = 1;
			}
#endif
		}
	}

	if (wsi->cache_secs && wsi->cache_reuse) {
		if (!wsi->cache_revalidate) {
			cc = cache_control;
			cclen = sprintf(cache_control, "%s, max-age=%u",
				    intermediates[wsi->cache_intermediaries],
				    wsi->cache_secs);
		} else {
			cc = cache_control;
			cclen = sprintf(cache_control,
					"must-revalidate, %s, max-age=%u",
                                intermediates[wsi->cache_intermediaries],
                                                    wsi->cache_secs);

		}
	}

	/* Only add cache control if its not specified by any other_headers. */
	if (!other_headers ||
	    (!strstr(other_headers, "cache-control") &&
	     !strstr(other_headers, "Cache-Control"))) {
		if (lws_add_http_header_by_token(wsi, WSI_TOKEN_HTTP_CACHE_CONTROL,
				(unsigned char *)cc, cclen, &p, end))
			return -1;
	}

	if (other_headers) {
		if ((end - p) < other_headers_len)
			return -1;
		memcpy(p, other_headers, other_headers_len);
		p += other_headers_len;
	}

	if (lws_finalize_http_header(wsi, &p, end))
		return -1;

	ret = lws_write(wsi, response, p - response, LWS_WRITE_HTTP_HEADERS);
	if (ret != (p - response)) {
		lwsl_err("_write returned %d from %ld\n", ret,
			 (long)(p - response));
		return -1;
	}

	wsi->http.filepos = 0;
	lwsi_set_state(wsi, LRS_ISSUING_FILE);

	lws_callback_on_writable(wsi);

	return 0;
}

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];
	struct lws_process_html_args args;
	lws_filepos_t amount, poss;
	unsigned char *p, *pstart;
#if defined(LWS_WITH_RANGES)
	unsigned char finished = 0;
#endif
	int n, m;

	lwsl_debug("wsi->http2_substream %d\n", wsi->http2_substream);

	do {

		/* priority 1: buffered output */

		if (lws_has_buffered_out(wsi)) {
			if (lws_issue_raw(wsi, NULL, 0) < 0) {
				lwsl_info("%s: closing\n", __func__);
				goto file_had_it;
			}
			break;
		}

		/* priority 2: buffered pre-compression-transform */

#if defined(LWS_WITH_HTTP_STREAM_COMPRESSION)
	if (wsi->http.comp_ctx.buflist_comp ||
	    wsi->http.comp_ctx.may_have_more) {
		enum lws_write_protocol wp = LWS_WRITE_HTTP;

		lwsl_info("%s: completing comp partial (buflist_comp %p, may %d)\n",
			   __func__, wsi->http.comp_ctx.buflist_comp,
			   wsi->http.comp_ctx.may_have_more);

		if (wsi->role_ops->write_role_protocol(wsi, NULL, 0, &wp) < 0) {
			lwsl_info("%s signalling to close\n", __func__);
			goto file_had_it;
		}
		lws_callback_on_writable(wsi);

		break;
	}
#endif

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

		n = 0;

		pstart = pt->serv_buf + LWS_H2_FRAME_HEADER_LENGTH;

		p = pstart;

#if defined(LWS_WITH_RANGES)
		if (wsi->http.range.count_ranges && !wsi->http.range.inside) {

			lwsl_notice("%s: doing range start %llu\n", __func__,
				    wsi->http.range.start);

			if ((long long)lws_vfs_file_seek_cur(wsi->http.fop_fd,
						   wsi->http.range.start -
						   wsi->http.filepos) < 0)
				goto file_had_it;

			wsi->http.filepos = wsi->http.range.start;

			if (wsi->http.range.count_ranges > 1) {
				n =  lws_snprintf((char *)p,
						context->pt_serv_buf_size -
						LWS_H2_FRAME_HEADER_LENGTH,
					"_lws\x0d\x0a"
					"Content-Type: %s\x0d\x0a"
					"Content-Range: bytes %llu-%llu/%llu\x0d\x0a"
					"\x0d\x0a",
					wsi->http.multipart_content_type,
					wsi->http.range.start,
					wsi->http.range.end,
					wsi->http.range.extent);
				p += n;
			}

			wsi->http.range.budget = wsi->http.range.end -
						   wsi->http.range.start + 1;
			wsi->http.range.inside = 1;
		}
#endif

		poss = context->pt_serv_buf_size - n - LWS_H2_FRAME_HEADER_LENGTH;

		if (wsi->http.tx_content_length)
			if (poss > wsi->http.tx_content_remain)
				poss = wsi->http.tx_content_remain;

		/*
		 * if there is a hint about how much we will do well to send at
		 * one time, restrict ourselves to only trying to send that.
		 */
		if (wsi->protocol->tx_packet_size &&
		    poss > wsi->protocol->tx_packet_size)
			poss = wsi->protocol->tx_packet_size;

		if (wsi->role_ops->tx_credit) {
			lws_filepos_t txc = wsi->role_ops->tx_credit(wsi);

			if (!txc) {
				lwsl_info("%s: came here with no tx credit\n",
						__func__);
				return 0;
			}
			if (txc < poss)
				poss = txc;

			/*
			 * consumption of the actual payload amount sent will be
			 * handled when the role data frame is sent
			 */
		}

#if defined(LWS_WITH_RANGES)
		if (wsi->http.range.count_ranges) {
			if (wsi->http.range.count_ranges > 1)
				poss -= 7; /* allow for final boundary */
			if (poss > wsi->http.range.budget)
				poss = wsi->http.range.budget;
		}
#endif
		if (wsi->sending_chunked) {
			/* we need to drop the chunk size in here */
			p += 10;
			/* allow for the chunk to grow by 128 in translation */
			poss -= 10 + 128;
		}

		if (lws_vfs_file_read(wsi->http.fop_fd, &amount, p, poss) < 0)
			goto file_had_it; /* caller will close */

		if (wsi->sending_chunked)
			n = (int)amount;
		else
			n = lws_ptr_diff(p, pstart) + (int)amount;

		lwsl_debug("%s: sending %d\n", __func__, n);

		if (n) {
			lws_set_timeout(wsi, PENDING_TIMEOUT_HTTP_CONTENT,
					context->timeout_secs);

			if (wsi->interpreting) {
				args.p = (char *)p;
				args.len = n;
				args.max_len = (unsigned int)poss + 128;
				args.final = wsi->http.filepos + n ==
					     wsi->http.filelen;
				args.chunked = wsi->sending_chunked;
				if (user_callback_handle_rxflow(
				     wsi->vhost->protocols[
				     (int)wsi->protocol_interpret_idx].callback,
				     wsi, LWS_CALLBACK_PROCESS_HTML,
				     wsi->user_space, &args, 0) < 0)
					goto file_had_it;
				n = args.len;
				p = (unsigned char *)args.p;
			} else
				p = pstart;

#if defined(LWS_WITH_RANGES)
			if (wsi->http.range.send_ctr + 1 ==
				wsi->http.range.count_ranges && // last range
			    wsi->http.range.count_ranges > 1 && // was 2+ ranges (ie, multipart)
			    wsi->http.range.budget - amount == 0) {// final part
				n += lws_snprintf((char *)pstart + n, 6,
					"_lws\x0d\x0a"); // append trailing boundary
				lwsl_debug("added trailing boundary\n");
			}
#endif
			m = lws_write(wsi, p, n,
				      wsi->http.filepos + amount == wsi->http.filelen ?
					LWS_WRITE_HTTP_FINAL :
					LWS_WRITE_HTTP
				);
			if (m < 0)
				goto file_had_it;

			wsi->http.filepos += amount;

#if defined(LWS_WITH_RANGES)
			if (wsi->http.range.count_ranges >= 1) {
				wsi->http.range.budget -= amount;
				if (wsi->http.range.budget == 0) {
					lwsl_notice("range budget exhausted\n");
					wsi->http.range.inside = 0;
					wsi->http.range.send_ctr++;

					if (lws_ranges_next(&wsi->http.range) < 1) {
						finished = 1;
						goto all_sent;
					}
				}
			}
#endif

			if (m != n) {
				/* adjust for what was not sent */
				if (lws_vfs_file_seek_cur(wsi->http.fop_fd,
							   m - n) ==
							     (lws_fileofs_t)-1)
					goto file_had_it;
			}
		}

all_sent:
		if ((!lws_has_buffered_out(wsi)
#if defined(LWS_WITH_HTTP_STREAM_COMPRESSION)
				&& !wsi->http.comp_ctx.buflist_comp &&
		    !wsi->http.comp_ctx.may_have_more
#endif
		    ) && (wsi->http.filepos >= wsi->http.filelen
#if defined(LWS_WITH_RANGES)
		    || finished)
#else
		)
#endif
		)
		     {
			lwsi_set_state(wsi, LRS_ESTABLISHED);
			/* we might be in keepalive, so close it off here */
			lws_vfs_file_close(&wsi->http.fop_fd);

			lwsl_debug("file completed\n");

			if (wsi->protocol->callback &&
			    user_callback_handle_rxflow(wsi->protocol->callback,
							wsi, LWS_CALLBACK_HTTP_FILE_COMPLETION,
							wsi->user_space, NULL,
							0) < 0) {
					/*
					 * For http/1.x, the choices from
					 * transaction_completed are either
					 * 0 to use the connection for pipelined
					 * or nonzero to hang it up.
					 *
					 * However for http/2. while we are
					 * still interested in hanging up the
					 * nwsi if there was a network-level
					 * fatal error, simply completing the
					 * transaction is a matter of the stream
					 * state, not the root connection at the
					 * network level
					 */
					if (wsi->http2_substream)
						return 1;
					else
						return -1;
				}

			return 1;  /* >0 indicates completed */
		}
	} while (1); //(!lws_send_pipe_choked(wsi));

	lws_callback_on_writable(wsi);

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

file_had_it:
	lws_vfs_file_close(&wsi->http.fop_fd);

	return -1;
}


LWS_VISIBLE void
lws_server_get_canonical_hostname(struct lws_context *context,
				  const struct lws_context_creation_info *info)
{
	if (lws_check_opt(info->options,
			LWS_SERVER_OPTION_SKIP_SERVER_CANONICAL_NAME))
		return;
#if !defined(LWS_WITH_ESP32)
	/* find canonical hostname */
	gethostname((char *)context->canonical_hostname,
		    sizeof(context->canonical_hostname) - 1);

	lwsl_info(" canonical_hostname = %s\n", context->canonical_hostname);
#else
	(void)context;
#endif
}


LWS_VISIBLE LWS_EXTERN int
lws_chunked_html_process(struct lws_process_html_args *args,
			 struct lws_process_html_state *s)
{
	char *sp, buffer[32];
	const char *pc;
	int old_len, n;

	/* do replacements */
	sp = args->p;
	old_len = args->len;
	args->len = 0;
	s->start = sp;
	while (sp < args->p + old_len) {

		if (args->len + 7 >= args->max_len) {
			lwsl_err("Used up interpret padding\n");
			return -1;
		}

		if ((!s->pos && *sp == '$') || s->pos) {
			int hits = 0, hit = 0;

			if (!s->pos)
				s->start = sp;
			s->swallow[s->pos++] = *sp;
			if (s->pos == sizeof(s->swallow) - 1)
				goto skip;
			for (n = 0; n < s->count_vars; n++)
				if (!strncmp(s->swallow, s->vars[n], s->pos)) {
					hits++;
					hit = n;
				}
			if (!hits) {
skip:
				s->swallow[s->pos] = '\0';
				memcpy(s->start, s->swallow, s->pos);
				args->len++;
				s->pos = 0;
				sp = s->start + 1;
				continue;
			}
			if (hits == 1 && s->pos == (int)strlen(s->vars[hit])) {
				pc = s->replace(s->data, hit);
				if (!pc)
					pc = "NULL";
				n = (int)strlen(pc);
				s->swallow[s->pos] = '\0';
				if (n != s->pos) {
					memmove(s->start + n,
						s->start + s->pos,
						old_len - (sp - args->p));
					old_len += (n - s->pos) + 1;
				}
				memcpy(s->start, pc, n);
				args->len++;
				sp = s->start + 1;

				s->pos = 0;
			}
			sp++;
			continue;
		}

		args->len++;
		sp++;
	}

	if (args->chunked) {
		/* no space left for final chunk trailer */
		if (args->final && args->len + 7 >= args->max_len)
			return -1;

		n = sprintf(buffer, "%X\x0d\x0a", args->len);

		args->p -= n;
		memcpy(args->p, buffer, n);
		args->len += n;

		if (args->final) {
			sp = args->p + args->len;
			*sp++ = '\x0d';
			*sp++ = '\x0a';
			*sp++ = '0';
			*sp++ = '\x0d';
			*sp++ = '\x0a';
			*sp++ = '\x0d';
			*sp++ = '\x0a';
			args->len += 7;
		} else {
			sp = args->p + args->len;
			*sp++ = '\x0d';
			*sp++ = '\x0a';
			args->len += 2;
		}
	}

	return 0;
}