Fix a bug where specifying an empty outboundproxy would cause packets to get sent to ourself.

(closes issue #15106)
Reported by: timeshell


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@195089 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -3097,6 +3097,11 @@ static int proxy_update(struct sip_proxy *proxy)
 static struct sip_proxy *proxy_allocate(char *name, char *port, int force)
 {
 	struct sip_proxy *proxy;
+
+	if (ast_strlen_zero(name)) {
+		return NULL;
+	}
+
 	proxy = ao2_alloc(sizeof(*proxy), NULL);
 	if (!proxy)
 		return NULL;