+/*
+ * Empire - A multi-player, client/server Internet based war game.
+ * Copyright (C) 1986-2005, Dave Pare, Jeff Bailey, Thomas Ruschak,
+ * Ken Stevens, Steve McClure
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * ---
+ *
+ * See the "LEGAL", "LICENSE", "CREDITS" and "README" files for all the
+ * related information and legal notices. It is expected that any future
+ * projects/authors will amend these files as needed.
+ *
+ * ---
+ *
+ * tcp_listen.c: Create a socket and listen on it
+ *
+ * Known contributors to this file:
+ * Markus Armbruster, 2005
+ */
+
+#include <config.h>
+
+#include <ctype.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <unistd.h>
+
+static int cant_listen(char *, char *, const char *);
+
+int
+tcp_listen(char *host, char *serv, size_t *addrlenp)
+{
+ int fd;
+ int on = 1;
+#ifdef HAVE_GETADDRINFO
+ /*
+ * Inspired by example code from W. Richard Stevens: UNIX Network
+ * Programming, Vol. 1
+ */
+ int n;
+ struct addrinfo hints, *res, *ressave;
+
+ memset(&hints, 0, sizeof(struct addrinfo));
+ hints.ai_flags = AI_PASSIVE;
+ hints.ai_family = AF_UNSPEC;
+ hints.ai_socktype = SOCK_STREAM;
+
+ if ((n = getaddrinfo(host, serv, &hints, &res)) != 0)
+ cant_listen(host, serv, gai_strerror(n));
+ ressave = res;
+
+ do {
+ fd = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
+ if (fd < 0)
+ continue; /* error, try next one */
+
+#ifndef _WIN32
+ /*
+ * SO_REUSEADDR requests to permit another bind even when the
+ * port is still in state TIME_WAIT. Windows' SO_REUSEADDR is
+ * broken: it makes bind() succeed no matter what, even if
+ * there's another server running on the same port. Luckily,
+ * bind() seems to be broken as well: it seems to suceed while
+ * the port in state TIME_WAIT by default; thus we get the
+ * behavior we want by not setting SO_REUSEADDR.
+ */
+ if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0)
+ cant_listen(host, serv, strerror(errno));
+#endif
+ if (bind(fd, res->ai_addr, res->ai_addrlen) == 0)
+ break; /* success */
+
+ close(fd); /* error, close and try next one */
+ } while ((res = res->ai_next) != NULL);
+
+ if (res == NULL) /* errno from final socket() or bind() */
+ cant_listen(host, serv, strerror(errno));
+
+ if (listen(fd, SOMAXCONN) < 0)
+ cant_listen(host, serv, strerror(errno));
+
+ if (addrlenp)
+ *addrlenp = res->ai_addrlen;
+
+ freeaddrinfo(ressave);
+
+#else /* !HAVE_GETADDRINFO */
+ struct sockaddr_in sin;
+ struct hostent *hp;
+ struct servent *sp;
+
+ memset(&sin, 0, sizeof(sin));
+ sin.sin_family = AF_INET;
+ if (!host)
+ sin.sin_addr.s_addr = htonl(INADDR_ANY);
+ else if (isdigit(*host))
+ sin.sin_addr.s_addr = inet_addr(host);
+ else {
+ hp = gethostbyname(host);
+ if (!hp)
+ cant_listen(host, serv, strerror(errno));
+ memcpy(&sin.sin_addr, hp->h_addr, sizeof(sin.sin_addr));
+ }
+ if (isdigit(*serv))
+ sin.sin_port = htons(atoi(serv));
+ else {
+ sp = getservbyname(serv, "tcp");
+ if (!sp)
+ cant_listen(host, serv, strerror(errno));
+ sin.sin_port = sp->s_port;
+ }
+ if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
+ cant_listen(host, serv, strerror(errno));
+#ifndef _WIN32
+ /* see comment on setsockopt() above */
+ if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)) < 0)
+ cant_listen(host, serv, strerror(errno));
+#endif
+ if (bind(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0)
+ cant_listen(host, serv, strerror(errno));
+ if (listen(fd, SOMAXCONN) < 0)
+ cant_listen(host, serv, strerror(errno));
+
+ if (addrlenp)
+ *addrlenp = sizeof(struct sockaddr_in);
+
+#endif /* !HAVE_GETADDRINFO */
+
+ return fd;
+}
+
+
+static int
+cant_listen(char *host, char *serv, const char *err)
+{
+ fprintf(stderr, "Can't listen on %s:%s: %s", host, serv, err);
+ exit(1);
+}