test: Add TestNode ipcbind option

With this change, tests can specify `self.extra_init = [{ipcbind: True}]` to
start a node listening on an IPC socket, instead of needing to choose which
node binary to invoke and what `self.extra_args=[["-ipcbind=..."]]` value to
pass to it.

The eliminates boilerplate code #30437 (interface_ipc_mining.py), #32297
(interface_ipc_cli.py), and #33201 (interface_ipc.py) previously needed in
their test setup.

test/functional/test_framework/test_framework.py

@@ -76,9 +76,9 @@ class Binaries:
         self.paths = paths
         self.bin_dir = bin_dir
 
-    def node_argv(self):
+    def node_argv(self, **kwargs):
         "Return argv array that should be used to invoke bitcoind"
-        return self._argv("node", self.paths.bitcoind)
+        return self._argv("node", self.paths.bitcoind, **kwargs)
 
     def rpc_argv(self):
         "Return argv array that should be used to invoke bitcoin-cli"
@@ -101,16 +101,19 @@ class Binaries:
         "Return argv array that should be used to invoke bitcoin-chainstate"
         return self._argv("chainstate", self.paths.bitcoinchainstate)
 
-    def _argv(self, command, bin_path):
+    def _argv(self, command, bin_path, need_ipc=False):
         """Return argv array that should be used to invoke the command. It
-        either uses the bitcoin wrapper executable (if BITCOIN_CMD is set), or
+        either uses the bitcoin wrapper executable (if BITCOIN_CMD is set or
-        the direct binary path (bitcoind, etc). When bin_dir is set (by tests
+        need_ipc is True), or the direct binary path (bitcoind, etc). When
-        calling binaries from previous releases) it always uses the direct
+        bin_dir is set (by tests calling binaries from previous releases) it
-        path."""
+        always uses the direct path."""
         if self.bin_dir is not None:
             return [os.path.join(self.bin_dir, os.path.basename(bin_path))]
-        elif self.paths.bitcoin_cmd is not None:
+        elif self.paths.bitcoin_cmd is not None or need_ipc:
-            return self.paths.bitcoin_cmd + [command]
+            # If the current test needs IPC functionality, use the bitcoin
+            # wrapper binary and append -m so it calls multiprocess binaries.
+            bitcoin_cmd = self.paths.bitcoin_cmd or [self.paths.bitcoin_bin]
+            return bitcoin_cmd + (["-m"] if need_ipc else []) + [command]
         else:
             return [bin_path]
 
@@ -158,6 +161,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
         self.noban_tx_relay: bool = False
         self.nodes: list[TestNode] = []
         self.extra_args = None
+        self.extra_init = None
         self.network_thread = None
         self.rpc_timeout = 60  # Wait for up to 60 seconds for the RPC server to respond
         self.supports_cli = True
@@ -553,15 +557,15 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
 
             bin_dirs.append(bin_dir)
 
+        extra_init = [{}] * num_nodes if self.extra_init is None else self.extra_init # type: ignore[var-annotated]
+        assert_equal(len(extra_init), num_nodes)
         assert_equal(len(extra_confs), num_nodes)
         assert_equal(len(extra_args), num_nodes)
         assert_equal(len(versions), num_nodes)
         assert_equal(len(bin_dirs), num_nodes)
         for i in range(num_nodes):
             args = list(extra_args[i])
-            test_node_i = TestNode(
+            init = dict(
-                i,
-                get_datadir_path(self.options.tmpdir, i),
                 chain=self.chain,
                 rpchost=rpchost,
                 timewait=self.rpc_timeout,
@@ -578,6 +582,11 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
                 v2transport=self.options.v2transport,
                 uses_wallet=self.uses_wallet,
             )
+            init.update(extra_init[i])
+            test_node_i = TestNode(
+                i,
+                get_datadir_path(self.options.tmpdir, i),
+                **init)
             self.nodes.append(test_node_i)
             if not test_node_i.version_is_at_least(170000):
                 # adjust conf for pre 17

test/functional/test_framework/test_node.py

@@ -11,6 +11,7 @@ from enum import Enum
 import json
 import logging
 import os
+import pathlib
 import platform
 import re
 import subprocess
@@ -19,6 +20,7 @@ import time
 import urllib.parse
 import collections
 import shlex
+import shutil
 import sys
 from pathlib import Path
 
@@ -52,6 +54,13 @@ CLI_MAX_ARG_SIZE = 131071 # many systems have a 128kb limit per arg (MAX_ARG_STR
 NULL_BLK_XOR_KEY = bytes([0] * NUM_XOR_BYTES)
 BITCOIN_PID_FILENAME_DEFAULT = "bitcoind.pid"
 
+if sys.platform.startswith("linux"):
+    UNIX_PATH_MAX = 108          # includes the trailing NUL
+elif sys.platform.startswith(("darwin", "freebsd", "netbsd", "openbsd")):
+    UNIX_PATH_MAX = 104
+else:                            # safest portable value
+    UNIX_PATH_MAX = 92
+
 
 class FailedToStartError(Exception):
     """Raised when a node fails to start correctly."""
@@ -77,7 +86,7 @@ class TestNode():
     To make things easier for the test writer, any unrecognised messages will
     be dispatched to the RPC connection."""
 
-    def __init__(self, i, datadir_path, *, chain, rpchost, timewait, timeout_factor, binaries, coverage_dir, cwd, extra_conf=None, extra_args=None, use_cli=False, start_perf=False, use_valgrind=False, version=None, v2transport=False, uses_wallet=False):
+    def __init__(self, i, datadir_path, *, chain, rpchost, timewait, timeout_factor, binaries, coverage_dir, cwd, extra_conf=None, extra_args=None, use_cli=False, start_perf=False, use_valgrind=False, version=None, v2transport=False, uses_wallet=False, ipcbind=False):
         """
         Kwargs:
             start_perf (bool): If True, begin profiling the node with `perf` as soon as
@@ -109,7 +118,7 @@ class TestNode():
         # Configuration for logging is set as command-line args rather than in the bitcoin.conf file.
         # This means that starting a bitcoind using the temp dir to debug a failed test won't
         # spam debug.log.
-        self.args = self.binaries.node_argv() + [
+        self.args = self.binaries.node_argv(need_ipc=ipcbind) + [
             f"-datadir={self.datadir_path}",
             "-logtimemicros",
             "-debug",
@@ -121,6 +130,17 @@ class TestNode():
         if uses_wallet is not None and not uses_wallet:
             self.args.append("-disablewallet")
 
+        self.ipc_tmp_dir = None
+        if ipcbind:
+            self.ipc_socket_path = self.chain_path / "node.sock"
+            if len(os.fsencode(self.ipc_socket_path)) < UNIX_PATH_MAX:
+                self.args.append("-ipcbind=unix")
+            else:
+                # Work around default CI path exceeding maximum socket path length.
+                self.ipc_tmp_dir = pathlib.Path(tempfile.mkdtemp(prefix="test-ipc-"))
+                self.ipc_socket_path = self.ipc_tmp_dir / "node.sock"
+                self.args.append(f"-ipcbind=unix:{self.ipc_socket_path}")
+
         # Use valgrind, expect for previous release binaries
         if use_valgrind and version is None:
             default_suppressions_file = Path(__file__).parents[3] / "contrib" / "valgrind.supp"
@@ -208,6 +228,9 @@ class TestNode():
             # this destructor is called.
             print(self._node_msg("Cleaning up leftover process"), file=sys.stderr)
             self.process.kill()
+        if self.ipc_tmp_dir:
+            print(self._node_msg(f"Cleaning up ipc directory {str(self.ipc_tmp_dir)!r}"))
+            shutil.rmtree(self.ipc_tmp_dir)
 
     def __getattr__(self, name):
         """Dispatches any unrecognised messages to the RPC connection or a CLI instance."""