Function in_pcbladdr

freebsd/netinet/in_pcb.c:1238–1440

* Do proper source address selection on an unbound socket in case * of connect. Take jails into account as well. */

 * of connect. Take jails into account as well.
 */
int
in_pcbladdr(struct inpcb *inp, struct in_addr *faddr, struct in_addr *laddr,
    struct ucred *cred)
{
	struct ifaddr *ifa;
	struct sockaddr *sa;
	struct sockaddr_in *sin, dst;
	struct nhop_object *nh;
	int error;

	NET_EPOCH_ASSERT();
	KASSERT(laddr != NULL, ("%s: laddr NULL", __func__));
	/*
	 * Bypass source address selection and use the primary jail IP
	 * if requested.
	 */
	if (cred != NULL && !prison_saddrsel_ip4(cred, laddr))
		return (0);

	error = 0;

	nh = NULL;
	bzero(&dst, sizeof(dst));
	sin = &dst;
	sin->sin_family = AF_INET;
	sin->sin_len = sizeof(struct sockaddr_in);
	sin->sin_addr.s_addr = faddr->s_addr;

	/*
	 * If route is known our src addr is taken from the i/f,
	 * else punt.
	 *
	 * Find out route to destination.
	 */
	if ((inp->inp_socket->so_options & SO_DONTROUTE) == 0)
		nh = fib4_lookup(inp->inp_inc.inc_fibnum, *faddr,
		    0, NHR_NONE, 0);

	/*
	 * If we found a route, use the address corresponding to
	 * the outgoing interface.
	 *
	 * Otherwise assume faddr is reachable on a directly connected
	 * network and try to find a corresponding interface to take
	 * the source address from.
	 */
	if (nh == NULL || nh->nh_ifp == NULL) {
		struct in_ifaddr *ia;
		struct ifnet *ifp;

		ia = ifatoia(ifa_ifwithdstaddr((struct sockaddr *)sin,
					inp->inp_socket->so_fibnum));
		if (ia == NULL) {
			ia = ifatoia(ifa_ifwithnet((struct sockaddr *)sin, 0,
						inp->inp_socket->so_fibnum));
		}
		if (ia == NULL) {
			error = ENETUNREACH;