dns: Fallback to A/AAAA lookup when getaddrinfo is used without any D…

…NS servers

include/re_dns.h

@@ -224,6 +224,7 @@ void dnsc_cache_flush(struct dnsc *dnsc);
 void dnsc_cache_max(struct dnsc *dnsc, uint32_t max);
 void dnsc_getaddrinfo(struct dnsc *dnsc, bool active);
 bool dnsc_getaddrinfo_enabled(struct dnsc *dnsc);
+bool dnsc_has_srv(const struct dnsc *dnsc);
 
 
 /* DNS System functions */

src/dns/client.c

@@ -975,9 +975,16 @@ static int query(struct dns_query **qp, struct dnsc *dnsc, uint8_t opcode,
 	struct dnshdr hdr;
 	int err = 0;
 
-	if (!dnsc || !name || !srvv || !srvc || !(*srvc))
+	if (!dnsc || !name)
 		return EINVAL;
 
+	if ((!srvv || !srvc || !(*srvc)) &&
+		(!dnsc->conf.getaddrinfo ||
+			(type != DNS_TYPE_A && type != DNS_TYPE_AAAA))) {
+
+		return EINVAL;
+	}
+
 	if (DNS_QTYPE_AXFR == type)
 		proto = IPPROTO_TCP;
 
@@ -1401,3 +1408,16 @@ bool dnsc_getaddrinfo_enabled(struct dnsc *dnsc)
 
 	return dnsc->conf.getaddrinfo;
 }
+
+
+/**
+ * Return whether any DNS servers are available
+ *
+ * @param dnsc  DNS Client
+ *
+ * @return true if DNS servers are available, false otherwise
+ */
+bool dnsc_has_srv(const struct dnsc *dnsc)
+{
+	return dnsc->srvc != 0;
+}

src/sip/request.c

@@ -737,7 +737,10 @@ static int sip_request_send(struct sip_request *req, struct sip *sip,
 			return err;
 		}
 	}
-	else if (route->port) {
+	else if (route->port ||
+			(req->tp_selected &&
+				!dnsc_has_srv(req->sip->dnsc) &&
+				dnsc_getaddrinfo_enabled(req->sip->dnsc))) {
 
 		req->port = sip_transp_port(req->tp, route->port);
 		err = addr_lookup(req, req->host);