Copyright 1996, Michiel Boland.
All rights reserved.

Redistribution and use in source and binary forms, with or
without modification, are permitted provided that the following
conditions are met:

1. Redistributions of source code must retain the above
copyright notice, this list of conditions and the following
disclaimer.

2. Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials
provided with the distribution.

3. The name of the author may not be used to endorse or promote
products derived from this software without specific prior
written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
THE POSSIBILITY OF SUCH DAMAGE.

diff -ur mathopd-1.6b12.orig/doc/syntax.txt mathopd-1.6b12/doc/syntax.txt
--- mathopd-1.6b12.orig/doc/syntax.txt	2006-11-05 04:58:33.000000000 +0900
+++ mathopd-1.6b12/doc/syntax.txt	2012-02-17 22:22:13.000000000 +0900
@@ -143,5 +143,4 @@
 socket-option-item:
 	"rcvbuf" integer
 	"sndbuf" integer
-	"v6only" flag
 	"nodelay" flag
diff -ur mathopd-1.6b12.orig/src/config.c mathopd-1.6b12/src/config.c
--- mathopd-1.6b12.orig/src/config.c	2011-12-03 10:49:58.000000000 +0900
+++ mathopd-1.6b12/src/config.c	2012-02-17 22:23:06.000000000 +0900
@@ -69,7 +69,7 @@
 	int line;
 };
 
-static int num_servers;
+static int num_server_sockets;
 static struct control *controls;
 static struct virtual *virtuals;
 
@@ -753,13 +753,6 @@
 			what = SO_INT;
 		} else
 #endif
-#ifdef IPV6_V6ONLY
-		if (!strcasecmp(p->tokbuf, "v6only")) {
-			l = IPPROTO_IPV6;
-			n = IPV6_V6ONLY;
-			what = SO_FLAG;
-		} else
-#endif
 #ifdef TCP_NODELAY
 		if (!strcasecmp(p->tokbuf, "nodelay")) {
 			l = IPPROTO_TCP;
@@ -802,11 +795,31 @@
 	return 0;
 }
 
+static const char *configsub_server_socket(struct addrinfo *res, struct server_socket **ss)
+{
+	struct server_socket *s;
+
+	if ((s = malloc(sizeof *s)) == 0)
+		return e_memory;
+	s->server_addr = malloc(res->ai_addrlen);
+	if (s->server_addr == 0)
+		return e_memory;
+	s->family = res->ai_family;
+	s->socktype = res->ai_socktype;
+	s->protocol = res->ai_protocol;
+	memcpy(s->server_addr, res->ai_addr, res->ai_addrlen);
+	s->server_addrlen = res->ai_addrlen;
+	num_server_sockets++;
+	s->next = *ss;
+	*ss = s;
+	return 0;
+}
+
 static const char *config_server(struct configuration *p, struct server **ss)
 {
 	struct server *s;
 	const char *t;
-	struct addrinfo hints, *res;
+	struct addrinfo hints, *res0, *res;
 	int rv, fam;
 
 	if ((s = malloc(sizeof *s)) == 0)
@@ -818,6 +831,7 @@
 	s->addr = 0;
 	s->options = 0;
 	s->port = 0;
+	s->sockets = 0;
 	fam = AF_UNSPEC;
 	if ((t = gettoken(p)) != t_open)
 		return t;
@@ -853,23 +867,19 @@
 	hints.ai_family = fam;
 	hints.ai_socktype = SOCK_STREAM;
 	hints.ai_protocol = 0;
-	rv = getaddrinfo(s->addr, s->port, &hints, &res);
+	rv = getaddrinfo(s->addr, s->port, &hints, &res0);
 	if (rv) {
 		fprintf(stderr, "address %s port %s: %s\n", s->addr ? s->addr : "[any]", s->port, gai_strerror(rv));
 		return e_illegalport;
 	}
-	s->server_addr = malloc(res->ai_addrlen);
-	if (s->server_addr == 0) {
-		freeaddrinfo(res);
-		return e_memory;
+	for (res = res0; res; res = res->ai_next) {
+		t = configsub_server_socket(res, &s->sockets);
+		if (t) {
+			freeaddrinfo(res0);
+			return t;
+		}
 	}
-	s->family = res->ai_family;
-	s->socktype = res->ai_socktype;
-	s->protocol = res->ai_protocol;
-	memcpy(s->server_addr, res->ai_addr, res->ai_addrlen);
-	s->server_addrlen = res->ai_addrlen;
-	freeaddrinfo(res);
-	num_servers++;
+	freeaddrinfo(res0);
 	s->next = *ss;
 	*ss = s;
 	return 0;
@@ -1047,7 +1057,7 @@
 
 int init_buffers(void)
 {
-	if (init_pollfds(2 * tuning.num_connections + num_servers) == -1)
+	if (init_pollfds(2 * tuning.num_connections + num_server_sockets) == -1)
 		return -1;
 	if (init_connections(tuning.num_connections) == -1)
 		return -1;
diff -ur mathopd-1.6b12.orig/src/core.c mathopd-1.6b12/src/core.c
--- mathopd-1.6b12.orig/src/core.c	2011-12-16 06:39:08.000000000 +0900
+++ mathopd-1.6b12/src/core.c	2012-02-17 22:22:13.000000000 +0900
@@ -201,14 +201,15 @@
 static void close_servers(void)
 {
 	struct server *s;
+	struct server_socket *ss;
 
-	s = servers;
-	while (s) {
-		if (s->fd != -1) {
-			close(s->fd);
-			s->fd = -1;
+	for (s = servers; s; s = s->next) {
+		for (ss = s->sockets; ss; ss = ss->next) {
+			if (ss->fd != -1) {
+				close(ss->fd);
+				ss->fd = -1;
+			}
 		}
-		s = s->next;
 	}
 }
 
@@ -263,7 +264,7 @@
 	p->ceiling = p->floor + n;
 }
 
-static int accept_connection(struct server *s)
+static int accept_connection(struct server *s, int listenfd)
 {
 	struct sockaddr_storage sa_remote, sa_local;
 	socklen_t l;
@@ -275,7 +276,7 @@
 		if (cn == 0)
 			return 0;
 		l = sizeof sa_remote;
-		fd = accept(s->fd, (struct sockaddr *) &sa_remote, &l);
+		fd = accept(listenfd, (struct sockaddr *) &sa_remote, &l);
 		if (fd == -1)
 			switch (errno) {
 			case EAGAIN:
@@ -662,16 +663,17 @@
 static int setup_server_pollfds(int n)
 {
 	struct server *s;
+	struct server_socket *ss;
 
-	s = servers;
-	while (s) {
-		if (s->fd != -1) {
-			pollfds[n].events = POLLIN;
-			pollfds[n].fd = s->fd;
-			s->pollno = n++;
-		} else
-			s->pollno = -1;
-		s = s->next;
+	for (s = servers; s; s = s->next) {
+		for (ss = s->sockets; ss; ss = ss->next) {
+			if (ss->fd != -1) {
+				pollfds[n].events = POLLIN;
+				pollfds[n].fd = ss->fd;
+				ss->pollno = n++;
+			} else
+				ss->pollno = -1;
+		}
 	}
 	return n;
 }
@@ -707,14 +709,15 @@
 static int run_servers(void)
 {
 	struct server *s;
+	struct server_socket *ss;
 
-	s = servers;
-	while (s) {
-		if (s->pollno != -1)
-			if (pollfds[s->pollno].revents & POLLIN)
-				if (accept_connection(s) == -1)
-					return -1;
-		s = s->next;
+	for (s = servers; s; s = s->next) {
+		for (ss = s->sockets; ss; ss = ss->next) {
+			if (ss->pollno != -1)
+				if (pollfds[ss->pollno].revents & POLLIN)
+					if (accept_connection(s, ss->fd) == -1)
+						return -1;
+		}
 	}
 	return 0;
 }
diff -ur mathopd-1.6b12.orig/src/main.c mathopd-1.6b12/src/main.c
--- mathopd-1.6b12.orig/src/main.c	2012-02-03 21:43:24.000000000 +0900
+++ mathopd-1.6b12/src/main.c	2012-02-17 22:22:13.000000000 +0900
@@ -41,6 +41,7 @@
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/resource.h>
+#include <netinet/in.h>
 #include <signal.h>
 #include <fcntl.h>
 #include <unistd.h>
@@ -99,31 +100,48 @@
 	exit(1);
 }
 
-static void startup_server(struct server *s)
+static void startup_server_socket(struct server *s, struct server_socket *ss)
 {
 	int onoff;
 	struct server_sockopts *o;
 
-	s->fd = socket(s->family, s->socktype, s->protocol);
-	if (s->fd == -1)
+	ss->fd = socket(ss->family, ss->socktype, ss->protocol);
+	if (ss->fd == -1)
 		die("socket", 0);
 	onoff = 1;
-	if (setsockopt(s->fd, SOL_SOCKET, SO_REUSEADDR, &onoff, sizeof onoff) == -1)
+	if (setsockopt(ss->fd, SOL_SOCKET, SO_REUSEADDR, &onoff, sizeof onoff) == -1)
 		die("setsockopt", "cannot set re-use flag");
+	if (ss->family == AF_INET6) {
+#ifdef IPV6_V6ONLY
+		onoff = 1;
+		if (setsockopt(ss->fd, IPPROTO_IPV6, IPV6_V6ONLY, &onoff, sizeof onoff) == -1)
+			die("setsockopt", "cannot set v6only flag");
+#else
+		die(0, "IPV6_V6ONLY is needed for IPv6 servers but not defined");
+#endif
+	}
 	o = s->options;
 	while (o) {
-		if (setsockopt(s->fd, o->ss_level, o->ss_optname, o->ss_optval, o->ss_optlen) == -1)
+		if (setsockopt(ss->fd, o->ss_level, o->ss_optname, o->ss_optval, o->ss_optlen) == -1)
 			die("setsockopt", 0);
 		o = o->next;
 	}
-	fcntl(s->fd, F_SETFD, FD_CLOEXEC);
-	fcntl(s->fd, F_SETFL, O_NONBLOCK);
-	if (bind(s->fd, s->server_addr, s->server_addrlen) == -1)
+	fcntl(ss->fd, F_SETFD, FD_CLOEXEC);
+	fcntl(ss->fd, F_SETFL, O_NONBLOCK);
+	if (bind(ss->fd, ss->server_addr, ss->server_addrlen) == -1)
 		die("bind", "cannot start up server at %s port %s", s->addr ? s->addr : "[any]", s->port);
-	if (listen(s->fd, s->backlog) == -1)
+	if (listen(ss->fd, s->backlog) == -1)
 		die("listen", 0);
 }
 
+static void startup_server(struct server *s)
+{
+	struct server_socket *ss;
+
+	for (ss = s->sockets; ss; ss = ss->next)
+		startup_server_socket(s, ss);
+}
+
 static void sighandler(int sig)
 {
 /*
diff -ur mathopd-1.6b12.orig/src/mathopd.h mathopd-1.6b12/src/mathopd.h
--- mathopd-1.6b12.orig/src/mathopd.h	2007-08-24 02:54:29.000000000 +0900
+++ mathopd-1.6b12/src/mathopd.h	2012-02-17 22:22:13.000000000 +0900
@@ -199,22 +199,27 @@
 	struct server_sockopts *next;
 };
 
-struct server {
+struct server_socket {
 	int fd;
 	size_t server_addrlen;
 	struct sockaddr *server_addr;
+	int pollno;
+	int family;
+	int socktype;
+	int protocol;
+	struct server_socket *next;
+};
+
+struct server {
 	struct virtual *children;
 	struct control *controls;
 	struct server *next;
-	int pollno;
 	struct vserver *vservers;
 	unsigned long backlog;
 	char *addr;
 	char *port;
-	int family;
-	int socktype;
-	int protocol;
 	struct server_sockopts *options;
+	struct server_socket *sockets;
 };
 
 struct request_header {