1 /* MIT License
2 *
3 * Copyright (c) 2024 Brad House
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a copy
6 * of this software and associated documentation files (the "Software"), to deal
7 * in the Software without restriction, including without limitation the rights
8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
9 * copies of the Software, and to permit persons to whom the Software is
10 * furnished to do so, subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice (including the next
13 * paragraph) shall be included in all copies or substantial portions of the
14 * 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 FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 * SOFTWARE.
23 *
24 * SPDX-License-Identifier: MIT
25 */
26
27 /* Some systems might default to something low like 256 (NetBSD), lets define
28 * this to assist. Really, no one should be using select, but lets be safe
29 * anyhow */
30 #define FD_SETSIZE 4096
31
32 #include "ares_private.h"
33 #include "ares_event.h"
34
35 /* All systems have select(), but not all have a way to wake, so we require
36 * pipe() to wake the select() */
37 #if defined(HAVE_PIPE) && defined(CARES_THREADS)
38
39 #ifdef HAVE_SYS_SELECT_H
40 # include <sys/select.h>
41 #endif
42
ares_evsys_select_init(ares_event_thread_t * e)43 static ares_bool_t ares_evsys_select_init(ares_event_thread_t *e)
44 {
45 e->ev_signal = ares_pipeevent_create(e);
46 if (e->ev_signal == NULL) {
47 return ARES_FALSE; /* LCOV_EXCL_LINE: UntestablePath */
48 }
49 return ARES_TRUE;
50 }
51
ares_evsys_select_destroy(ares_event_thread_t * e)52 static void ares_evsys_select_destroy(ares_event_thread_t *e)
53 {
54 (void)e;
55 }
56
ares_evsys_select_event_add(ares_event_t * event)57 static ares_bool_t ares_evsys_select_event_add(ares_event_t *event)
58 {
59 (void)event;
60 return ARES_TRUE;
61 }
62
ares_evsys_select_event_del(ares_event_t * event)63 static void ares_evsys_select_event_del(ares_event_t *event)
64 {
65 (void)event;
66 }
67
ares_evsys_select_event_mod(ares_event_t * event,ares_event_flags_t new_flags)68 static void ares_evsys_select_event_mod(ares_event_t *event,
69 ares_event_flags_t new_flags)
70 {
71 (void)event;
72 (void)new_flags;
73 }
74
ares_evsys_select_wait(ares_event_thread_t * e,unsigned long timeout_ms)75 static size_t ares_evsys_select_wait(ares_event_thread_t *e,
76 unsigned long timeout_ms)
77 {
78 size_t num_fds = 0;
79 ares_socket_t *fdlist = ares_htable_asvp_keys(e->ev_sock_handles, &num_fds);
80 int rv;
81 size_t cnt = 0;
82 size_t i;
83 fd_set read_fds;
84 fd_set write_fds;
85 fd_set except_fds;
86 int nfds = 0;
87 struct timeval tv;
88 struct timeval *tout = NULL;
89
90 FD_ZERO(&read_fds);
91 FD_ZERO(&write_fds);
92 FD_ZERO(&except_fds);
93
94 for (i = 0; i < num_fds; i++) {
95 const ares_event_t *ev =
96 ares_htable_asvp_get_direct(e->ev_sock_handles, fdlist[i]);
97 if (ev->flags & ARES_EVENT_FLAG_READ) {
98 FD_SET(ev->fd, &read_fds);
99 }
100 if (ev->flags & ARES_EVENT_FLAG_WRITE) {
101 FD_SET(ev->fd, &write_fds);
102 }
103 FD_SET(ev->fd, &except_fds);
104 if (ev->fd + 1 > nfds) {
105 nfds = ev->fd + 1;
106 }
107 }
108
109 if (timeout_ms) {
110 tv.tv_sec = (int)(timeout_ms / 1000);
111 tv.tv_usec = (int)((timeout_ms % 1000) * 1000);
112 tout = &tv;
113 }
114
115 rv = select(nfds, &read_fds, &write_fds, &except_fds, tout);
116 if (rv > 0) {
117 for (i = 0; i < num_fds; i++) {
118 ares_event_t *ev;
119 ares_event_flags_t flags = 0;
120
121 ev = ares_htable_asvp_get_direct(e->ev_sock_handles, fdlist[i]);
122 if (ev == NULL || ev->cb == NULL) {
123 continue; /* LCOV_EXCL_LINE: DefensiveCoding */
124 }
125
126 if (FD_ISSET(fdlist[i], &read_fds) || FD_ISSET(fdlist[i], &except_fds)) {
127 flags |= ARES_EVENT_FLAG_READ;
128 }
129
130 if (FD_ISSET(fdlist[i], &write_fds)) {
131 flags |= ARES_EVENT_FLAG_WRITE;
132 }
133
134 if (flags == 0) {
135 continue;
136 }
137
138 cnt++;
139
140 ev->cb(e, fdlist[i], ev->data, flags);
141 }
142 }
143
144 ares_free(fdlist);
145
146 return cnt;
147 }
148
149 const ares_event_sys_t ares_evsys_select = {
150 "select",
151 ares_evsys_select_init,
152 ares_evsys_select_destroy, /* NoOp */
153 ares_evsys_select_event_add, /* NoOp */
154 ares_evsys_select_event_del, /* NoOp */
155 ares_evsys_select_event_mod, /* NoOp */
156 ares_evsys_select_wait
157 };
158
159 #endif
160