- Retry for interfaces with unused ports if possible.

doc/Changelog

@@ -1,6 +1,7 @@
 12 November 2020: Wouter
 	- Fix to connect() to UDP destinations, default turned on,
 	  this lowers vulnerability to ICMP side channels.
+	- Retry for interfaces with unused ports if possible.
 
 10 November 2020: Wouter
 	- Fix #341: fixing a possible memory leak.

services/outside_network.c

@@ -1118,6 +1118,9 @@ select_ifport(struct outside_network* outnet, struct pending* pend,
 		if(1) {
 			/* if we connect() we cannot reuse fds for a port */
 			if(pif->inuse >= pif->avail_total) {
+				tries++;
+				if(tries < MAX_PORT_RETRY)
+					continue;
 				log_err("failed to find an open port, drop msg");
 				return 0;
 			}