mgcp: add prefix to virtual trunk

the virtual trunk is addressed without a prefix (just *@domain).

- reorganize find_endpoint() so that it accepts a prefix when
  addressing the virtual trunk.

- do no longer accept wildcarded CRCX requests without prefix
  (will not break anything, the feature of wildcarded CRCX is
  not in use yet)

- keep the old prefix-less method but print a warning that it is
  depreacted.

Change-Id: I2aac3ba0f1f3122dfbb3bf36f74198ecb2b21de5
diff --git a/src/libosmo-mgcp/mgcp_protocol.c b/src/libosmo-mgcp/mgcp_protocol.c
index 16e9cb8..daedc8d 100644
--- a/src/libosmo-mgcp/mgcp_protocol.c
+++ b/src/libosmo-mgcp/mgcp_protocol.c
@@ -198,9 +198,12 @@
 {
 	int rc;
 
-	if (endp->wildcarded_crcx) {
-		rc = msgb_printf(msg, "Z: %u@%s\n", ENDPOINT_NUMBER(endp),
-				 endp->cfg->domain);
+	/* NOTE: Only in the virtual trunk we allow dynamic endpoint names */
+	if (endp->wildcarded_crcx
+	    && endp->tcfg->trunk_type == MGCP_TRUNK_VIRTUAL) {
+		rc = msgb_printf(msg, "Z: %s%u@%s\n",
+				 MGCP_ENDPOINT_PREFIX_VIRTUAL_TRUNK,
+				 ENDPOINT_NUMBER(endp), endp->cfg->domain);
 		if (rc < 0)
 			return -EINVAL;
 	}