net: don't relay to the address' originator

For each address to be relayed we "randomly" pick 2 nodes to send the
address to (in `RelayAddress()`). However we do not take into
consideration that it does not make sense to relay the address back to
its originator (`CNode::PushAddress()` will do nothing in that case).

This means that if the originator is among the "randomly" picked nodes,
then we will relay to one node less than intended.

Fix this by skipping the originating node when choosing candidates to
relay to.

1 files changed, 28 insertions, 9 deletions

diff --git a/test/functional/p2p_addr_relay.py b/test/functional/p2p_addr_relay.py
index 80f262d0d3..91fbd722cf 100755
--- a/test/functional/p2p_addr_relay.py
+++ b/test/functional/p2p_addr_relay.py
@@ -19,8 +19,11 @@ from test_framework.util import (
 )
 import time
 
+# Keep this with length <= 10. Addresses from larger messages are not relayed.
 ADDRS = []
-for i in range(10):
+num_ipv4_addrs = 10
+
+for i in range(num_ipv4_addrs):
     addr = CAddress()
     addr.time = int(time.time()) + i
     addr.nServices = NODE_NETWORK | NODE_WITNESS
@@ -30,11 +33,15 @@ for i in range(10):
 
 
 class AddrReceiver(P2PInterface):
+    num_ipv4_received = 0
+
     def on_addr(self, message):
         for addr in message.addrs:
             assert_equal(addr.nServices, 9)
+            if not 8333 <= addr.port < 8343:
+                raise AssertionError("Invalid addr.port of {} (8333-8342 expected)".format(addr.port))
             assert addr.ip.startswith('123.123.123.')
-            assert (8333 <= addr.port < 8343)
+            self.num_ipv4_received += 1
 
 
 class AddrTest(BitcoinTestFramework):
@@ -48,21 +55,33 @@ class AddrTest(BitcoinTestFramework):
         msg = msg_addr()
 
         self.log.info('Send too-large addr message')
-        msg.addrs = ADDRS * 101
+        msg.addrs = ADDRS * 101  # more than 1000 addresses in one message
         with self.nodes[0].assert_debug_log(['addr message size = 1010']):
             addr_source.send_and_ping(msg)
 
         self.log.info('Check that addr message content is relayed and added to addrman')
-        addr_receiver = self.nodes[0].add_p2p_connection(AddrReceiver())
+        num_receivers = 7
+        receivers = []
+        for _ in range(num_receivers):
+            receivers.append(self.nodes[0].add_p2p_connection(AddrReceiver()))
         msg.addrs = ADDRS
-        with self.nodes[0].assert_debug_log([
-                'Added 10 addresses from 127.0.0.1: 0 tried',
+        with self.nodes[0].assert_debug_log(
+            [
+                'Added {} addresses from 127.0.0.1: 0 tried'.format(num_ipv4_addrs),
                 'received: addr (301 bytes) peer=0',
-                'sending addr (301 bytes) peer=1',
-        ]):
+            ]
+        ):
             addr_source.send_and_ping(msg)
             self.nodes[0].setmocktime(int(time.time()) + 30 * 60)
-            addr_receiver.sync_with_ping()
+            for receiver in receivers:
+                receiver.sync_with_ping()
+
+        total_ipv4_received = sum(r.num_ipv4_received for r in receivers)
+
+        # Every IPv4 address must be relayed to two peers, other than the
+        # originating node (addr_source).
+        ipv4_branching_factor = 2
+        assert_equal(total_ipv4_received, num_ipv4_addrs * ipv4_branching_factor)
 
 
 if __name__ == '__main__':