[test] Test that we only relay addrs to peers who sent us addr relate…

…d messages

The `AddrReceiver` class used in the existing tests sends a `getaddr` message
to indicate that it is interested in participating in address relay. This
commit introduces another class, `AddrBlackhole` which does not initiate any
addr related messages. The tests check that addresses received via the network
are forwarded to the `AddrReceiver` and not the `AddrBlackhole`

test/functional/p2p_addr_relay.py

@@ -36,6 +36,15 @@ def on_addr(self, message):
             self.num_ipv4_received += 1
 
 
+class AddrBlackhole(P2PInterface):
+    """ Does not initiate any addr related messages """
+    num_ipv4_received = 0
+
+    def on_addr(self, message):
+        for addr in message.addrs:
+            self.num_ipv4_received += 1
+
+
 class AddrTest(BitcoinTestFramework):
     counter = 0
 
@@ -45,6 +54,7 @@ def set_test_params(self):
     def run_test(self):
         self.oversized_addr_test()
         self.relay_tests()
+        self.blackhole_tests()
 
     def setup_addr_msg(self, num, add_delay=False):
         addrs = []
@@ -105,6 +115,25 @@ def relay_tests(self):
 
         self.nodes[0].disconnect_p2ps()
 
+    def blackhole_tests(self):
+        self.log.info('Check that we only relay addresses to peers who have previously sent us addr related messages')
+
+        addr_source = self.nodes[0].add_p2p_connection(P2PInterface())
+        receiver_peer = self.nodes[0].add_p2p_connection(AddrReceiver())
+        blackhole_peer = self.nodes[0].add_p2p_connection(AddrBlackhole())
+
+        msg = self.setup_addr_msg(2, add_delay=True)
+        addr_source.send_and_ping(msg)
+        # pop m_next_addr_send timer
+        self.nodes[0].setmocktime(int(time.time()) + 30 * 60 * 2)
+        receiver_peer.sync_with_ping()
+        blackhole_peer.sync_with_ping()
+
+        assert_equal(receiver_peer.num_ipv4_received, 2)
+        assert_equal(blackhole_peer.num_ipv4_received, 0)
+
+        self.nodes[0].disconnect_p2ps()
+
 
 if __name__ == '__main__':
     AddrTest().main()