/* $OpenBSD: udp.c,v 1.92 2005/10/27 08:19:59 hshoexer Exp $	 */
/* $EOM: udp.c,v 1.57 2001/01/26 10:09:57 niklas Exp $	 */

/*
 * Copyright (c) 1998, 1999, 2001 Niklas Hallqvist.  All rights reserved.
 * Copyright (c) 2000 Angelos D. Keromytis.  All rights reserved.
 * Copyright (c) 2003, 2004 Håkan Olsson.  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.
 *
 * 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 LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This code was written under funding by Ericsson Radio Systems.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <limits.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "conf.h"
#include "if.h"
#include "isakmp.h"
#include "log.h"
#include "message.h"
#include "monitor.h"
#include "transport.h"
#include "udp.h"
#include "util.h"
#include "virtual.h"

#define UDP_SIZE 65536

/* If a system doesn't have SO_REUSEPORT, SO_REUSEADDR will have to do. */
#ifndef SO_REUSEPORT
#define SO_REUSEPORT SO_REUSEADDR
#endif

/* These are reused by udp_encap.c, thus not 'static' here.  */
struct transport *udp_clone(struct transport *, struct sockaddr *);
int		  udp_fd_set(struct transport *, fd_set *, int);
int		  udp_fd_isset(struct transport *, fd_set *);
void		  udp_get_dst(struct transport *, struct sockaddr **);
void		  udp_get_src(struct transport *, struct sockaddr **);
char		 *udp_decode_ids(struct transport *);
void		  udp_remove(struct transport *);

static struct transport *udp_create(char *);
static void     udp_report(struct transport *);
static void     udp_handle_message(struct transport *);
static struct transport *udp_make(struct sockaddr *);
static int      udp_send_message(struct message *, struct transport *);

static struct transport_vtbl udp_transport_vtbl = {
	{0}, "udp_physical",
	udp_create,
	0,
	udp_remove,
	udp_report,
	udp_fd_set,
	udp_fd_isset,
	udp_handle_message,
	udp_send_message,
	udp_get_dst,
	udp_get_src,
	udp_decode_ids,
	udp_clone,
	0
};

char		*udp_default_port = 0;
int		 bind_family = 0;

void
udp_init(void)
{
	transport_method_add(&udp_transport_vtbl);
}

/* Create a UDP transport structure bound to LADDR just for listening.  */
static struct transport *
udp_make(struct sockaddr *laddr)
{
	struct udp_transport *t = 0;
	int	s, on, wildcardaddress = 0;
	char	*tstr;

	t = calloc(1, sizeof *t);
	if (!t) {
		log_print("udp_make: calloc (1, %lu) failed",
		    (unsigned long)sizeof *t);
		free(laddr);
		return 0;
	}
	t->src = laddr;

	s = socket(laddr->sa_family, SOCK_DGRAM, IPPROTO_UDP);
	if (s == -1) {
		log_error("udp_make: socket (%d, %d, %d)", laddr->sa_family,
		    SOCK_DGRAM, IPPROTO_UDP);
		goto err;
	}
	/* Make sure we don't get our traffic encrypted.  */
	if (sysdep_cleartext(s, laddr->sa_family) == -1)
		goto err;

	/* Wildcard address ?  */
	switch (laddr->sa_family) {
	case AF_INET:
		if (((struct sockaddr_in *)laddr)->sin_addr.s_addr ==
		    INADDR_ANY)
			wildcardaddress = 1;
		break;
	case AF_INET6:
		if (IN6_IS_ADDR_UNSPECIFIED(&((struct sockaddr_in6 *)laddr)->sin6_addr))
			wildcardaddress = 1;
		break;
	}

	/*
	 * In order to have several bound specific address-port combinations
	 * with the same port SO_REUSEADDR is needed.  If this is a wildcard
	 * socket and we are not listening there, but only sending from it
	 * make sure it is entirely reuseable with SO_REUSEPORT.
	 */
	on = 1;
	if (setsockopt(s, SOL_SOCKET,
	    wildcardaddress ? SO_REUSEPORT : SO_REUSEADDR,
	    (void *)&on, sizeof on) == -1) {
		log_error("udp_make: setsockopt (%d, %d, %d, %p, %lu)", s,
		    SOL_SOCKET, wildcardaddress ? SO_REUSEPORT : SO_REUSEADDR,
		    &on, (unsigned long)sizeof on);
		goto err;
	}
	t->transport.vtbl = &udp_transport_vtbl;
	if (monitor_bind(s, t->src, SA_LEN(t->src))) {
		if (sockaddr2text(t->src, &tstr, 0))
			log_error("udp_make: bind (%d, %p, %lu)", s, &t->src,
			    (unsigned long)sizeof t->src);
		else {
			log_error("udp_make: bind (%d, %s, %lu)", s, tstr,
			    (unsigned long)sizeof t->src);
			free(tstr);
		}
		goto err;
	}
	t->s = s;
	if (sockaddr2text(t->src, &tstr, 0))
		LOG_DBG((LOG_MISC, 20, "udp_make: "
		    "transport %p socket %d family %d", t, s,
		    t->src->sa_family == AF_INET ? 4 : 6));
	else {
		LOG_DBG((LOG_MISC, 20, "udp_make: "
		    "transport %p socket %d ip %s port %d", t, s,
		    tstr, ntohs(sockaddr_port(t->src))));
		free (tstr);
	}
	transport_setup(&t->transport, 0);
	t->transport.flags |= TRANSPORT_LISTEN;
	return &t->transport;

err:
	if (s >= 0)
		close(s);
	if (t) {
		/* Already closed.  */
		t->s = -1;
		udp_remove(&t->transport);
	}
	return 0;
}

/* Clone a listen transport U, record a destination RADDR for outbound use.  */
struct transport *
udp_clone(struct transport *ut, struct sockaddr *raddr)
{
	struct udp_transport *u = (struct udp_transport *)ut;
	struct udp_transport *u2;
	struct transport *t;

	t = malloc(sizeof *u);
	if (!t) {
		log_error("udp_clone: malloc (%lu) failed",
		    (unsigned long)sizeof *u);
		return 0;
	}
	u2 = (struct udp_transport *)t;

	memcpy(u2, u, sizeof *u);

	u2->src = malloc(SA_LEN(u->src));
	if (!u2->src) {
		log_error("udp_clone: malloc (%lu) failed",
		    (unsigned long)SA_LEN(u->src));
		free(t);
		return 0;
	}
	memcpy(u2->src, u->src, SA_LEN(u->src));

	u2->dst = malloc(SA_LEN(raddr));
	if (!u2->dst) {
		log_error("udp_clone: malloc (%lu) failed",
		    (unsigned long)SA_LEN(raddr));
		free(u2->src);
		free(t);
		return 0;
	}
	memcpy(u2->dst, raddr, SA_LEN(raddr));

	t->flags &= ~TRANSPORT_LISTEN;
	transport_setup(t, 0);
	return t;
}

/*
 * Initialize an object of the UDP transport class.  Fill in the local
 * IP address and port information and create a server socket bound to
 * that specific port.  Add the polymorphic transport structure to the
 * system-wide pools of known ISAKMP transports.
 */
struct transport *
udp_bind(const struct sockaddr *addr)
{
	struct sockaddr *src;

	src = malloc(SA_LEN(addr));
	if (!src)
		return 0;

	memcpy(src, addr, SA_LEN(addr));
	return udp_make(src);
}

/*
 * NAME is a section name found in the config database.  Setup and return
 * a transport useable to talk to the peer specified by that name.
 */
static struct transport *
udp_create(char *name)
{
	struct virtual_transport *v;
	struct udp_transport *u;
	struct transport *rv;
	struct sockaddr	*dst, *addr;
	char	*addr_str, *port_str;
	struct conf_list *addr_list = 0;
	struct conf_list_node *addr_node;

	port_str = conf_get_str(name, "Port");
	if (!port_str)
		port_str = udp_default_port;
	if (!port_str)
		port_str = UDP_DEFAULT_PORT_STR;

	addr_str = conf_get_str(name, "Address");
	if (!addr_str) {
		log_print("udp_create: no address configured for \"%s\"",
		    name);
		return 0;
	}
	if (text2sockaddr(addr_str, port_str, &dst, 0, 0)) {
		log_print("udp_create: address \"%s\" not understood",
		    addr_str);
		return 0;
	}
	addr_str = conf_get_str(name, "Local-address");
	if (!addr_str)
		addr_list = conf_get_list("General", "Listen-on");
	if (!addr_str && !addr_list) {
		v = virtual_get_default(dst->sa_family);
		u = (struct udp_transport *)v->main;

		if (!u) {
			log_print("udp_create: no default transport");
			rv = 0;
			goto ret;
		} else {
			rv = udp_clone((struct transport *)u, dst);
			if (rv)
				rv->vtbl = &udp_transport_vtbl;
			goto ret;
		}
	}

	if (addr_list) {
		for (addr_node = TAILQ_FIRST(&addr_list->fields);
		    addr_node; addr_node = TAILQ_NEXT(addr_node, link))
			if (text2sockaddr(addr_node->field,
			    port_str, &addr, 0, 0) == 0) {
				v = virtual_listen_lookup(addr);
				free(addr);
				if (v) {
					addr_str = addr_node->field;
					break;
				}
			}
		if (!addr_str) {
			log_print("udp_create: no matching listener found");
			rv = 0;
			goto ret;
		}
	}
	if (text2sockaddr(addr_str, port_str, &addr, 0, 0)) {
		log_print("udp_create: address \"%s\" not understood",
		    addr_str);
		rv = 0;
		goto ret;
	}

	v = virtual_listen_lookup(addr);
	free(addr);
	if (!v) {
		log_print("udp_create: %s:%s must exist as a listener too",
		    addr_str, port_str);
		rv = 0;
		goto ret;
	}
	rv = udp_clone(v->main, dst);
	if (rv)
		rv->vtbl = &udp_transport_vtbl;

ret:
	if (addr_list)
		conf_free_list(addr_list);
	free(dst);
	return rv;
}

void
udp_remove(struct transport *t)
{
	struct udp_transport *u = (struct udp_transport *)t;
	struct transport *p;

	if (u->src)
		free(u->src);
	if (u->dst)
		free(u->dst);
	if ((t->flags & TRANSPORT_LISTEN) && u->s >= 0)
		close(u->s);

	for (p = LIST_FIRST(&transport_list); p && p != t; p =
	    LIST_NEXT(p, link))
		;
	if (p == t)
		LIST_REMOVE(t, link);

	LOG_DBG((LOG_TRANSPORT, 90, "udp_remove: removed transport %p", t));
	free(t);
}

/* Report transport-method specifics of the T transport. */
void
udp_report(struct transport *t)
{
	struct udp_transport *u = (struct udp_transport *)t;
	char		*src = NULL, *dst = NULL;
	in_port_t	 sport, dport;

	if (sockaddr2text(u->src, &src, 0))
		goto ret;
	sport = sockaddr_port(u->src);

	if (!u->dst || sockaddr2text(u->dst, &dst, 0))
		dst = 0;
	dport = dst ? sockaddr_port(u->dst) : 0;

	LOG_DBG((LOG_REPORT, 0, "udp_report: fd %d src %s:%u dst %s:%u", u->s,
	    src, ntohs(sport), dst ? dst : "<none>", ntohs(dport)));

ret:
	if (dst)
		free(dst);
	if (src)
		free(src);
}

/*
 * A message has arrived on transport T's socket.  If T is single-ended,
 * clone it into a double-ended transport which we will use from now on.
 * Package the message as we want it and continue processing in the message
 * module.
 */
static void
udp_handle_message(struct transport *t)
{
	struct udp_transport *u = (struct udp_transport *)t;
	u_int8_t        buf[UDP_SIZE];
	struct sockaddr_storage from;
	u_int32_t       len = sizeof from;
	ssize_t         n;
	struct message *msg;

	n = recvfrom(u->s, buf, UDP_SIZE, 0, (struct sockaddr *)&from, &len);
	if (n == -1) {
		log_error("recvfrom (%d, %p, %d, %d, %p, %p)", u->s, buf,
		    UDP_SIZE, 0, &from, &len);
		return;
	}

	if (t->virtual == (struct transport *)virtual_get_default(AF_INET) ||
	    t->virtual == (struct transport *)virtual_get_default(AF_INET6)) {
		t->virtual->vtbl->reinit();

		/*
		 * As we don't know the actual destination address of the
		 * packet, we can't really deal with it. So, just ignore it
		 * and hope we catch the retransmission.
		 */
		return;
	}

	/*
	 * Make a specialized UDP transport structure out of the incoming
	 * transport and the address information we got from recvfrom(2).
	 */
	t = t->virtual->vtbl->clone(t->virtual, (struct sockaddr *)&from);
	if (!t)
		return;

	msg = message_alloc(t, buf, n);
	if (!msg) {
		log_error("failed to allocate message structure, dropping "
		    "packet received on transport %p", u);
		t->vtbl->remove(t);
		return;
	}
	message_recv(msg);
}

/* Physically send the message MSG over its associated transport.  */
static int
udp_send_message(struct message *msg, struct transport *t)
{
	struct udp_transport *u = (struct udp_transport *)t;
	ssize_t         n;
	struct msghdr   m;

	/*
	 * Sending on connected sockets requires that no destination address is
	 * given, or else EISCONN will occur.
	 */
	m.msg_name = (caddr_t) u->dst;
	m.msg_namelen = SA_LEN(u->dst);
	m.msg_iov = msg->iov;
	m.msg_iovlen = msg->iovlen;
	m.msg_control = 0;
	m.msg_controllen = 0;
	m.msg_flags = 0;
	n = sendmsg(u->s, &m, 0);
	if (n == -1) {
		/* XXX We should check whether the address has gone away */
		log_error("sendmsg (%d, %p, %d)", u->s, &m, 0);
		return -1;
	}
	return 0;
}

int
udp_fd_set(struct transport *t, fd_set *fds, int bit)
{
	struct udp_transport		*u = (struct udp_transport *)t;

	if (bit)
		FD_SET(u->s, fds);
	else
		FD_CLR(u->s, fds);

	return u->s + 1;
}

int
udp_fd_isset(struct transport *t, fd_set *fds)
{
	struct udp_transport		*u = (struct udp_transport *)t;

	return FD_ISSET(u->s, fds);
}

/*
 * Get transport T's peer address and stuff it into the sockaddr pointed
 * to by DST.
 */
void
udp_get_dst(struct transport *t, struct sockaddr **dst)
{
	*dst = ((struct udp_transport *)t)->dst;
}

/*
 * Get transport T's local address and stuff it into the sockaddr pointed
 * to by SRC.  Put its length into SRC_LEN.
 */
void
udp_get_src(struct transport *t, struct sockaddr **src)
{
	*src = ((struct udp_transport *)t)->src;
}

char *
udp_decode_ids(struct transport *t)
{
	struct sockaddr *src, *dst;
	static char     result[1024];
	char            idsrc[256], iddst[256];

	t->vtbl->get_src(t, &src);
	t->vtbl->get_dst(t, &dst);

	if (getnameinfo(src, SA_LEN(src), idsrc, sizeof idsrc, NULL, 0,
	    NI_NUMERICHOST) != 0) {
		log_print("udp_decode_ids: getnameinfo () failed for 'src'");
		strlcpy(idsrc, "<error>", 256);
	}
	if (getnameinfo(dst, SA_LEN(dst), iddst, sizeof iddst, NULL, 0,
	    NI_NUMERICHOST) != 0) {
		log_print("udp_decode_ids: getnameinfo () failed for 'dst'");
		strlcpy(iddst, "<error>", 256);
	}

	snprintf(result, sizeof result, "src: %s dst: %s", idsrc, iddst);
	return result;
}