domain: Do not report errors when domain cannot be extracted from URI.

We should not report an error to syslog when lookup_domain fails to
parse the URI it was given as argument. That URI usually comes from
SIP messages we received from another implementation and we cannot
guarantee that they will always be well-formed. Generating an error
each time we receive a malformed SIP message can easily result in
denial of service.

modules_s/domain/domain_mod.c

@@ -440,7 +440,7 @@ static int lookup_domain(struct sip_msg* msg, char* flags, char* fp)
 	track = 0;
 
 	if (get_str_fparam(&domain, msg, (fparam_t*)fp) != 0) {
-		ERR("Cannot get domain name to lookup\n");
+		DBG("lookup_domain: Cannot get the domain name to lookup\n");
 		return -1;
 	}