Merge #16618: [Fix] Allow connection of a noban banned peer

05066cf Add test for setban (nicolas.dorier)
48e0bd3 [Fix] Allow connection of a noban banned peer (nicolas.dorier)

Pull request description:

  Reported by @MarcoFalke on bitcoin/bitcoin#16248 (comment)

  The bug would mean that if the peer connecting to you is banned, but whitelisted without specific permissions, it would not be able to connect to the node.

  The solution is just to move the same line below.

ACKs for top commit:
  Sjors:
    Agree inline is more clear. utACK 05066cf
  MarcoFalke:
    ACK 05066cf

Tree-SHA512: 0fed39acb1e8db67bb0bf4c4de3ad034ae776f38d55bd661f1ae0e1a4c6becaf1824ab46ed8279f2f31df3f4b29ff56461d8b167d3e9cece62cfe58b5a912811

src/net.cpp

@@ -906,7 +906,6 @@ void CConnman::AcceptConnection(const ListenSocket& hListenSocket) {
     NetPermissionFlags permissionFlags = NetPermissionFlags::PF_NONE;
     hListenSocket.AddSocketPermissionFlags(permissionFlags);
     AddWhitelistPermissionFlags(permissionFlags, addr);
-    const bool noban = NetPermissions::HasFlag(permissionFlags, NetPermissionFlags::PF_NOBAN);
     bool legacyWhitelisted = false;
     if (NetPermissions::HasFlag(permissionFlags, NetPermissionFlags::PF_ISIMPLICIT)) {
         NetPermissions::ClearFlag(permissionFlags, PF_ISIMPLICIT);
@@ -953,7 +952,7 @@ void CConnman::AcceptConnection(const ListenSocket& hListenSocket) {
 
     // Don't accept connections from banned peers, but if our inbound slots aren't almost full, accept
     // if the only banning reason was an automatic misbehavior ban.
-    if (!noban && bannedlevel > ((nInbound + 1 < nMaxInbound) ? 1 : 0))
+    if (!NetPermissions::HasFlag(permissionFlags, NetPermissionFlags::PF_NOBAN) && bannedlevel > ((nInbound + 1 < nMaxInbound) ? 1 : 0))
     {
         LogPrint(BCLog::NET, "connection from %s dropped (banned)\n", addr.ToString());
         CloseSocket(hSocket);

test/functional/rpc_setban.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+# Copyright (c) 2015-2019 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test the setban rpc call."""
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    connect_nodes,
+    p2p_port
+)
+
+class SetBanTests(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 2
+        self.setup_clean_chain = True
+        self.extra_args = [[],[]]
+
+    def run_test(self):
+        # Node 0 connects to Node 1, check that the noban permission is not granted
+        connect_nodes(self.nodes[0], 1)
+        peerinfo = self.nodes[1].getpeerinfo()[0]
+        assert(not 'noban' in peerinfo['permissions'])
+
+        # Node 0 get banned by Node 1
+        self.nodes[1].setban("127.0.0.1", "add")
+
+        # Node 0 should not be able to reconnect
+        with self.nodes[1].assert_debug_log(expected_msgs=['dropped (banned)\n']):
+            self.restart_node(1, [])
+            self.nodes[0].addnode("127.0.0.1:" + str(p2p_port(1)), "onetry")
+
+        # However, node 0 should be able to reconnect if it has noban permission
+        self.restart_node(1, ['-whitelist=127.0.0.1'])
+        connect_nodes(self.nodes[0], 1)
+        peerinfo = self.nodes[1].getpeerinfo()[0]
+        assert('noban' in peerinfo['permissions'])
+
+        # If we remove the ban, Node 0 should be able to reconnect even without noban permission
+        self.nodes[1].setban("127.0.0.1", "remove")
+        self.restart_node(1, [])
+        connect_nodes(self.nodes[0], 1)
+        peerinfo = self.nodes[1].getpeerinfo()[0]
+        assert(not 'noban' in peerinfo['permissions'])
+
+if __name__ == '__main__':
+    SetBanTests().main()

test/functional/test_runner.py

@@ -146,6 +146,7 @@
     'rpc_net.py',
     'wallet_keypool.py',
     'p2p_mempool.py',
+    'rpc_setban.py',
     'p2p_blocksonly.py',
     'mining_prioritisetransaction.py',
     'p2p_invalid_locator.py',

test/lint/lint-spelling.ignore-words.txt

@@ -12,3 +12,4 @@ cachable
 errorstring
 keyserver
 homogenous
+setban