net: don't extra bind for Tor if binds are restricted

If only `-bind=addr:port` is given (without `-bind=...=onion`) then we
would bind to `addr:port` _and_ to `127.0.0.1:8334` in addition which
may be unexpected, assuming the semantic of `-bind=addr:port` is
"bind _only_ to `addr:port`".

Change the above to not do the additional bind: if only
`-bind=addr:port` is given (without `-bind=...=onion`) then bind to
`addr:port` (only). If we are creating a Tor hidden service then use
`addr:port` as target (same behavior as before
bitcoin#19991).

This allows disabling binding on the onion port.

Fixes bitcoin#22726

src/init.cpp

@@ -1732,6 +1732,8 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
     CService onion_service_target;
     if (!connOptions.onion_binds.empty()) {
         onion_service_target = connOptions.onion_binds.front();
+    } else if (!connOptions.vBinds.empty()) {
+        onion_service_target = connOptions.vBinds.front();
     } else {
         onion_service_target = DefaultOnionServiceTarget();
         connOptions.onion_binds.push_back(onion_service_target);

test/functional/feature_bind_extra.py

@@ -21,16 +21,20 @@
     PORT_MIN,
     PORT_RANGE,
     assert_equal,
+    p2p_port,
     rpc_port,
 )
 
+# From chainparamsbase.cpp:CreateBaseChainParams().
+REGTEST_TOR_TARGET_PORT = 18445
+
 class BindExtraTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         # Avoid any -bind= on the command line. Force the framework to avoid
         # adding -bind=127.0.0.1.
         self.bind_to_localhost_only = False
-        self.num_nodes = 2
+        self.num_nodes = 4
 
     def setup_network(self):
         # Override setup_network() because we want to put the result of
@@ -43,6 +47,7 @@ def setup_network(self):
         if not sys.platform.startswith('linux'):
             raise SkipTest("This test can only be run on Linux.")
 
+        any_ipv4 = addr_to_hex('0.0.0.0')
         loopback_ipv4 = addr_to_hex("127.0.0.1")
 
         # Start custom ports after p2p and rpc ports.
@@ -69,14 +74,29 @@ def setup_network(self):
         )
         port += 2
 
+        # Node2, no -bind, expected to bind on any + tor target.
+        self.expected.append(
+            [
+                ["-listen=1"],
+                [(any_ipv4, p2p_port(2)), (loopback_ipv4, REGTEST_TOR_TARGET_PORT)]
+            ]
+        )
+
+        # Node3, no -bind=...=onion, thus no extra port for Tor target.
+        self.expected.append(
+            [
+                ['-bind=127.0.0.1:{}'.format(port)],
+                [(loopback_ipv4, port)]
+            ],
+        )
+        port += 1
+
         self.extra_args = list(map(lambda e: e[0], self.expected))
-        self.add_nodes(self.num_nodes, self.extra_args)
-        # Don't start the nodes, as some of them would collide trying to bind on the same port.
+        self.setup_nodes()
 
     def run_test(self):
         for i in range(len(self.expected)):
-            self.log.info(f"Starting node {i} with {self.expected[i][0]}")
-            self.start_node(i)
+            self.log.info(f"Checking listening ports of node {i} with {self.expected[i][0]}")
             pid = self.nodes[i].process.pid
             binds = set(get_bind_addrs(pid))
             # Remove IPv6 addresses because on some CI environments "::1" is not configured
@@ -88,8 +108,6 @@ def run_test(self):
             # Remove RPC ports. They are not relevant for this test.
             binds = set(filter(lambda e: e[1] != rpc_port(i), binds))
             assert_equal(binds, set(self.expected[i][1]))
-            self.stop_node(i)
-            self.log.info(f"Stopped node {i}")
 
 if __name__ == '__main__':
     BindExtraTest().main()