2 files changed, 26 insertions, 4 deletions

diff --git a/src/ot_config.c b/src/ot_config.c
index 36f50a6..6b51c61 100644
--- a/src/ot_config.c
+++ b/src/ot_config.c
@@ -320,7 +320,7 @@ static int parse_configfile(char *config_filename) {
         int off     = scan_ip6_port(p, tmpip, &tmpport);
 
         if (!off || !listen_scan_options(p + off, &shared, &workers))
-          goto parse_error;
+          exerr("listen.tcp, listen.udp and listen.tcp_udp want an address, optionally a port and options.");
         if (kind != CONFIG_LISTEN_UDP)
           listen_append(tmpip, tmpport, FLAG_TCP, shared, workers), ++bound;
         if (kind != CONFIG_LISTEN_TCP)
@@ -446,7 +446,7 @@ static void help(char *name) {
   fprintf(stderr, "\nExample:   ./opentracker -i 127.0.0.1 -p 6969 -P 6969 -f ./opentracker.conf -i 10.1.1.23 -p 2710 -p 80\n");
   fprintf(stderr, "           Here -i 127.0.0.1 selects the ip address for the next -p 6969 and -P 6969.\n");
   fprintf(stderr, "           If no port is bound from config file or command line, the last address given\n");
-  fprintf(stderr, "           (or ::1 if none is set) will be used on port 6969.\n");
+  fprintf(stderr, "           is used on port 6969, and every interface if none was given.\n");
 }
 #undef HELPLINE
 
diff --git a/tests/integration/test_config.py b/tests/integration/test_config.py
index 1a84fa7..2f6bdc4 100644
--- a/tests/integration/test_config.py
+++ b/tests/integration/test_config.py
@@ -1,7 +1,9 @@
 """Settings the tracker has to accept, and still work with.
 
-An unrecognised key makes opentracker refuse to start, so a test that it
-comes up at all is a test that the key was understood.
+An unrecognised key only warns, so coming up proves nothing on its own and a
+test that cares has to look at what the tracker said. A key that is
+recognised but cannot be parsed is another matter, and for the listen
+statements it stops the tracker.
 """
 
 import unittest
@@ -14,6 +16,7 @@ class TcpWorkers(TrackerTestCase):
 
     def test_the_tracker_serves_with_tcp_workers_asked_for(self):
         self.assertEqual(self.tracker.announce(self.hash_for("tcpworkers"))[b"complete"], 1)
+        self.assertNotIn("Unhandled line", self.tracker.output())
 
 
 class WorkersOnAListenStatement(unittest.TestCase):
@@ -27,3 +30,22 @@ class WorkersOnAListenStatement(unittest.TestCase):
             self.assertEqual(complaints, [], "the tracker reported:\n" + "\n".join(complaints))
         finally:
             tracker._cleanup()
+
+
+class AListenLineThatDoesNotParse(unittest.TestCase):
+    """Warning and carrying on left a tracker that had been told where to
+    listen coming up on its default instead, which is every interface."""
+
+    def refuses(self, line):
+        with self.assertRaises(AssertionError) as caught:
+            Tracker(line)
+        return str(caught.exception)
+
+    def test_an_address_that_is_not_one_stops_the_tracker(self):
+        self.assertIn("want an address", self.refuses("listen.tcp 10.0.0.300:7999\n"))
+
+    def test_so_does_a_port_out_of_range(self):
+        self.assertIn("want an address", self.refuses("listen.udp 127.0.0.1:99999\n"))
+
+    def test_so_does_an_option_it_does_not_know(self):
+        self.assertIn("want an address", self.refuses("listen.tcp 127.0.0.1:7999 wokers=2\n"))