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1 /*
2  * libwebsockets - small server side websockets and web server implementation
3  *
4  * Copyright (C) 2010 - 2020 Andy Green <andy@warmcat.com>
5  *
6  * Permission is hereby granted, free of charge, to any person obtaining a copy
7  * of this software and associated documentation files (the "Software"), to
8  * deal in the Software without restriction, including without limitation the
9  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10  * sell copies of the Software, and to permit persons to whom the Software is
11  * furnished to do so, subject to the following conditions:
12  *
13  * The above copyright notice and this permission notice shall be included in
14  * all copies or substantial portions of the Software.
15  *
16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22  * IN THE SOFTWARE.
23  */
24 
25 #include "private-lib-core.h"
26 
27 int
lws_plat_pipe_create(struct lws * wsi)28 lws_plat_pipe_create(struct lws *wsi)
29 {
30 	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
31 	struct sockaddr_in *si = &wsi->context->frt_pipe_si;
32 	lws_sockfd_type *fd = pt->dummy_pipe_fds;
33 
34 	/*
35 	 * There's no pipe abstraction on lwip / freertos... use a UDP socket
36 	 * listening on 127.0.0.1:54321 and send a byte to it from a second UDP
37 	 * socket to cancel the wait.
38 	 */
39 
40 	fd[0] = socket(AF_INET, SOCK_DGRAM, 0);
41 	if (fd[0] < 0)
42 		goto bail;
43 
44 	fd[1] = socket(AF_INET, SOCK_DGRAM, 0);
45 	if (fd[1] < 0)
46 		goto bail;
47 
48 	/*
49 	 * No need for memset since it's in zalloc'd context... it's in the
50 	 * context so we can reuse the prepared sockaddr to send tp fd[0] whem
51 	 * we want to cancel the wait
52 	 */
53 
54 	si->sin_family = AF_INET;
55 	si->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
56 	si->sin_port = htons(54321);
57 
58 	if (bind(fd[0], (const struct sockaddr *)si, sizeof(*si)) < 0)
59 		goto bail;
60 
61 	return 0;
62 
63 bail:
64 	lwsl_err("%s: failed\n", __func__);
65 
66 	return 1;
67 }
68 
69 int
lws_plat_pipe_signal(struct lws * wsi)70 lws_plat_pipe_signal(struct lws *wsi)
71 {
72 	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
73 	struct sockaddr_in *si = &wsi->context->frt_pipe_si;
74 	lws_sockfd_type *fd = pt->dummy_pipe_fds;
75 	uint8_t u = 0;
76 	int n;
77 
78 	/*
79 	 * Send a single UDP byte payload to the listening socket fd[0], forcing
80 	 * the event loop wait to wake.  fd[1] and context->frt_pipe_si are
81 	 * set at context creation and are static, the UDP sendto is supposed to
82 	 * be threadsafe for lwip:
83 	 *
84 	 * https://lwip.fandom.com/wiki/LwIP_and_multithreading
85 	 *
86 	 * Sockets generally can't be used by more than one application thread
87 	 * (on udp/raw netconn, doing a sendto/recv is currently possible).
88 	 */
89 
90 	n = sendto(fd[1], &u, 1, 0, (struct sockaddr *)si, sizeof(*si));
91 
92 	return n != 1;
93 }
94 
95 void
lws_plat_pipe_close(struct lws * wsi)96 lws_plat_pipe_close(struct lws *wsi)
97 {
98 	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
99 	lws_sockfd_type *fd = pt->dummy_pipe_fds;
100 
101 	if (fd[0] && fd[0] != -1)
102 		close(fd[0]);
103 	if (fd[1] && fd[1] != -1)
104 		close(fd[1]);
105 
106 	fd[0] = fd[1] = -1;
107 }
108