Function get_local_sockname

connectd/netaddress.c:199–224

Trick I learned from Harald Welte: create UDP socket, connect() and * then query address. */ Returns 0 if protocol completely unsupported, ADDR_LISTEN if we * can't reach addr, ADDR_LISTEN_AND_ANNOUNCE if we can (and fill saddr). */

/* Returns 0 if protocol completely unsupported, ADDR_LISTEN if we
 * can't reach addr, ADDR_LISTEN_AND_ANNOUNCE if we can (and fill saddr). */
static bool get_local_sockname(int af, void *saddr, socklen_t saddrlen)
{
    int fd = socket(af, SOCK_DGRAM, 0);
    if (fd < 0) {
        status_debug("Failed to create %u socket: %s",
                     af, strerror(errno));
        return false;
    }

    if (connect(fd, saddr, saddrlen) != 0) {
        status_debug("Failed to connect %u socket: %s",
                     af, strerror(errno));
        close(fd);
        return false;
    }

    if (getsockname(fd, saddr, &saddrlen) != 0) {
        status_debug("Failed to get %u socket name: %s",
                     af, strerror(errno));
        close(fd);
        return false;
    }

    close(fd);
    return true;
}

bool guess_address(struct wireaddr *addr)
{