net/linux/addrs: fix point-to-point peer address bug

On point-to-point networks IFA_ADDRESS points to the peer address
instead of the local address.

    /*
     * Important comment:
     * IFA_ADDRESS is prefix address, rather than local interface address.
     * It makes no difference for normally configured broadcast interfaces,
     * but for point-to-point IFA_ADDRESS is DESTINATION address,
     * local address is supplied in IFA_LOCAL attribute.
    */

src/net/linux/addrs.c

@@ -111,8 +111,17 @@ static bool parse_msg_addr(struct nlmsghdr *msg, ssize_t len,
 
 		if (ifa->ifa_family == AF_INET) {
 			sa_init(&sa, AF_INET);
-			sa.u.in.sin_addr.s_addr =
-				*(uint32_t *)RTA_DATA(rta_tb[IFA_ADDRESS]);
+			if (rta_tb[IFA_LOCAL]) {
+				/* looks like point-to-point network, use local
+				 * address, instead of peer */
+				sa.u.in.sin_addr.s_addr = *(
+					uint32_t *)RTA_DATA(rta_tb[IFA_LOCAL]);
+			}
+			else {
+				sa.u.in.sin_addr.s_addr =
+					*(uint32_t *)RTA_DATA(
+						rta_tb[IFA_ADDRESS]);
+			}
 		}
 		else if (ifa->ifa_family == AF_INET6) {
 			sa_set_in6(&sa, RTA_DATA(rta_tb[IFA_ADDRESS]), 0);