test: add functional test for -port behavior

Author: mzumsande

test/functional/feature_port.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+# Copyright (c) 2024-present 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 -port option and its interactions with
+-bind.
+"""
+
+from test_framework.test_framework import (
+    BitcoinTestFramework,
+)
+from test_framework.util import (
+    p2p_port,
+)
+
+
+class PortTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        # Avoid any -bind= on the command line.
+        self.bind_to_localhost_only = False
+        self.num_nodes = 1
+
+    def run_test(self):
+        node = self.nodes[0]
+        node.has_explicit_bind = True
+        port1 = p2p_port(self.num_nodes)
+        port2 = p2p_port(self.num_nodes + 5)
+
+        self.log.info("When starting with -port, bitcoind binds to it and uses port + 1 for an onion bind")
+        with node.assert_debug_log(expected_msgs=[f'Bound to 0.0.0.0:{port1}', f'Bound to 127.0.0.1:{port1 + 1}']):
+            self.restart_node(0, extra_args=["-listen", f"-port={port1}"])
+
+        self.log.info("When specifying -port multiple times, only the last one is taken")
+        with node.assert_debug_log(expected_msgs=[f'Bound to 0.0.0.0:{port2}', f'Bound to 127.0.0.1:{port2 + 1}'], unexpected_msgs=[f'Bound to 0.0.0.0:{port1}']):
+            self.restart_node(0, extra_args=["-listen", f"-port={port1}", f"-port={port2}"])
+
+        self.log.info("When specifying ports with both -port and -bind, the one from -port is ignored")
+        with node.assert_debug_log(expected_msgs=[f'Bound to 0.0.0.0:{port2}'], unexpected_msgs=[f'Bound to 0.0.0.0:{port1}']):
+            self.restart_node(0, extra_args=["-listen", f"-port={port1}", f"-bind=0.0.0.0:{port2}"])
+
+        self.log.info("When -bind specifies no port, the values from -port and -bind are combined")
+        with self.nodes[0].assert_debug_log(expected_msgs=[f'Bound to 0.0.0.0:{port1}']):
+            self.restart_node(0, extra_args=["-listen", f"-port={port1}", "-bind=0.0.0.0"])
+
+        self.log.info("When an onion bind specifies no port, the value from -port, incremented by 1, is taken")
+        with self.nodes[0].assert_debug_log(expected_msgs=[f'Bound to 127.0.0.1:{port1 + 1}']):
+            self.restart_node(0, extra_args=["-listen", f"-port={port1}", "-bind=127.0.0.1=onion"])
+
+        self.log.info("Invalid values for -port raise errors")
+        self.stop_node(0)
+        node.extra_args = ["-listen", "-port=65536"]
+        node.assert_start_raises_init_error(expected_msg="Error: Invalid port specified in -port: '65536'")
+        node.extra_args = ["-listen", "-port=0"]
+        node.assert_start_raises_init_error(expected_msg="Error: Invalid port specified in -port: '0'")
+
+
+if __name__ == '__main__':
+    PortTest(__file__).main()

test/functional/test_runner.py

@@ -339,6 +339,7 @@
     'feature_minchainwork.py',
     'rpc_estimatefee.py',
     'rpc_getblockstats.py',
+    'feature_port.py',
     'feature_bind_port_externalip.py',
     'wallet_create_tx.py --legacy-wallet',
     'wallet_send.py --legacy-wallet',