2 * Empire - A multi-player, client/server Internet based war game.
3 * Copyright (C) 1986-2018, Dave Pare, Jeff Bailey, Thomas Ruschak,
4 * Ken Stevens, Steve McClure, Markus Armbruster
6 * Empire is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
21 * See files README, COPYING and CREDITS in the root of the source
22 * tree for related information and legal notices. It is expected
23 * that future projects/authors will amend these files as needed.
27 * tcp_listen.c: Create a socket and listen on it
29 * Known contributors to this file:
30 * Markus Armbruster, 2005-2013
41 #include <sys/types.h>
42 #include <sys/socket.h>
43 #include <netinet/in.h>
44 #include <arpa/inet.h>
47 #include "prototypes.h"
49 /* Portability cruft, should become unnecessary eventually */
51 #define AI_ADDRCONFIG 0
54 static void cant_listen(char *, char *, const char *)
55 ATTRIBUTE((noreturn));
58 tcp_listen(char *host, char *serv, size_t *addrlenp)
62 #ifdef HAVE_GETADDRINFO
64 * Inspired by example code from W. Richard Stevens: UNIX Network
68 struct addrinfo hints, *first_ai, *ai;
69 /* Crap necessary for OpenBSD, see below */
70 int try_v6only_off = 1, v6only_stuck = 0;
72 memset(&hints, 0, sizeof(struct addrinfo));
73 hints.ai_flags = AI_PASSIVE | AI_ADDRCONFIG;
74 hints.ai_family = AF_UNSPEC;
75 hints.ai_socktype = SOCK_STREAM;
77 if ((err = getaddrinfo(host, serv, &hints, &first_ai)) != 0)
78 cant_listen(host, serv, gai_strerror(err));
82 for (ai = first_ai; ai; ai = ai->ai_next) {
83 fd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
85 continue; /* error, try next one */
88 if (ai->ai_family == AF_INET6 && try_v6only_off) {
91 if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY,
92 &off, sizeof(off)) < 0) {
94 * IPV6_V6ONLY is stuck on, violating RFC 3493 (gee,
95 * thanks, OpenBSD!). Address is good only for IPv6,
96 * not for IPv4. Means we can't have both on this
97 * system. Continue looking for one that's good for
106 (void)try_v6only_off;
109 setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
110 if (bind(fd, ai->ai_addr, ai->ai_addrlen) == 0)
113 close(fd); /* error, close and try next one */
116 /* More crap for OpenBSD */
117 if (ai == NULL && v6only_stuck) {
119 * No go. But we skipped IPv6 addresses that don't work for
120 * IPv4, but could for IPv6. Try again without skipping
127 if (ai == NULL) /* errno from final socket() or bind() */
128 cant_listen(host, serv, strerror(errno));
130 if (listen(fd, SOMAXCONN) < 0)
131 cant_listen(host, serv, strerror(errno));
134 *addrlenp = ai->ai_addrlen;
136 freeaddrinfo(first_ai);
138 #else /* !HAVE_GETADDRINFO */
139 struct sockaddr_in sin;
143 memset(&sin, 0, sizeof(sin));
144 sin.sin_family = AF_INET;
146 sin.sin_addr.s_addr = htonl(INADDR_ANY);
147 else if (isdigit(*host))
148 sin.sin_addr.s_addr = inet_addr(host);
150 hp = gethostbyname(host);
152 cant_listen(host, serv, strerror(errno));
153 memcpy(&sin.sin_addr, hp->h_addr, sizeof(sin.sin_addr));
156 sin.sin_port = htons(atoi(serv));
158 sp = getservbyname(serv, "tcp");
160 cant_listen(host, serv, strerror(errno));
161 sin.sin_port = sp->s_port;
163 if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
164 cant_listen(host, serv, strerror(errno));
165 setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
166 if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0)
167 cant_listen(host, serv, strerror(errno));
168 if (listen(fd, SOMAXCONN) < 0)
169 cant_listen(host, serv, strerror(errno));
172 *addrlenp = sizeof(struct sockaddr_in);
174 #endif /* !HAVE_GETADDRINFO */
180 cant_listen(char *host, char *serv, const char *err)
182 fprintf(stderr, "Can't listen on %s%s%s: %s\n",
183 host ? host : "", host ? ":" : "", serv, err);