[sr-dev] [kamailio/kamailio] Hostname only (no ports) in the advertise parameter should be allowed (#1884)

### Description The `advertise` option in a `listen` parameter seems to only allow the following syntax: `advertise ip_or_host:port` The `advertise ip_or_host` syntax is not allowed and gives the following error: This can be blocking when using DNS SRV features in order to retrieve both host and port to send the SIP messages: when a port is present in the record-route/via headers no DNS SRV are done. So it prevents from doing some DNS-based load-balancing / failover things. ### Troubleshooting We get the same behaviour with using the deprecated `advertised_address` parameter: default port is set by Kamailio (because it is not possible to force a _null_ value for `advertised_port`) in the _Via_ header (but does not seem to affect the _R-R_ header). The advertised address can only be forced for the _Record-Route_ header using the `record_route_advertised_address` function in the script. ### Additional Information Tested with last Kamailio release on Debian 9.8 ``` version: kamailio 5.2.1 (x86_64/linux) flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144 MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB poll method support: poll, epoll_lt, epoll_et, sigio_rt, select. id: unknown compiled with gcc 6.3.0 ``` -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/kamailio/kamailio/issues/1884