From 16c274dbffef6ff23f6044f6cbb40b3c12d01054 Mon Sep 17 00:00:00 2001
From: Drake Aiman <daiman776@gmail.com>
Date: Tue, 13 May 2025 11:18:54 -0700
Subject: [PATCH 1/5] Add initial support for IPv6

---
 src/debugpy/adapter/__main__.py  | 14 +++++---
 src/debugpy/adapter/clients.py   | 19 +++++-----
 src/debugpy/adapter/launchers.py |  7 ++--
 src/debugpy/adapter/servers.py   |  4 +--
 src/debugpy/common/sockets.py    | 60 +++++++++++++++++++++++++++-----
 src/debugpy/launcher/__init__.py |  3 +-
 src/debugpy/launcher/__main__.py |  7 ++--
 src/debugpy/server/api.py        | 10 +++---
 src/debugpy/server/cli.py        |  7 ++--
 tests/debug/comms.py             |  2 +-
 tests/debug/session.py           |  3 +-
 tests/debugpy/server/test_cli.py |  6 ++--
 tests/debugpy/test_attach.py     | 19 ++++++----
 13 files changed, 113 insertions(+), 48 deletions(-)

diff --git a/src/debugpy/adapter/__main__.py b/src/debugpy/adapter/__main__.py
index 93cd05f6d..43a7e5118 100644
--- a/src/debugpy/adapter/__main__.py
+++ b/src/debugpy/adapter/__main__.py
@@ -65,9 +65,10 @@ def main():
     else:
         endpoints["client"] = {"host": client_host, "port": client_port}
 
+    localhost = sockets.get_default_localhost()
     if args.for_server is not None:
         try:
-            server_host, server_port = servers.serve()
+            server_host, server_port = servers.serve(localhost)
         except Exception as exc:
             endpoints = {"error": "Can't listen for server connections: " + str(exc)}
         else:
@@ -80,10 +81,11 @@ def main():
         )
 
         try:
-            sock = sockets.create_client()
+            ipv6 = True if localhost.count(":") > 1 else False
+            sock = sockets.create_client(ipv6)
             try:
                 sock.settimeout(None)
-                sock.connect(("127.0.0.1", args.for_server))
+                sock.connect((localhost, args.for_server))
                 sock_io = sock.makefile("wb", 0)
                 try:
                     sock_io.write(json.dumps(endpoints).encode("utf-8"))
@@ -137,6 +139,10 @@ def delete_listener_file():
 
 
 def _parse_argv(argv):
+    from debugpy.common import sockets
+
+    host = sockets.get_default_localhost()
+
     parser = argparse.ArgumentParser()
 
     parser.add_argument(
@@ -154,7 +160,7 @@ def _parse_argv(argv):
     parser.add_argument(
         "--host",
         type=str,
-        default="127.0.0.1",
+        default=host,
         metavar="HOST",
         help="start the adapter in debugServer mode on the specified host",
     )
diff --git a/src/debugpy/adapter/clients.py b/src/debugpy/adapter/clients.py
index 0b4a870a7..186c1ab6d 100644
--- a/src/debugpy/adapter/clients.py
+++ b/src/debugpy/adapter/clients.py
@@ -404,7 +404,8 @@ def property_or_debug_option(prop_name, flag_name):
             self._forward_terminate_request = on_terminate == "KeyboardInterrupt"
 
         launcher_path = request("debugLauncherPath", os.path.dirname(launcher.__file__))
-        adapter_host = request("debugAdapterHost", "127.0.0.1")
+        localhost = sockets.get_default_localhost()
+        adapter_host = request("debugAdapterHost", localhost)
 
         try:
             servers.serve(adapter_host)
@@ -477,15 +478,16 @@ def attach_request(self, request):
                 raise request.isnt_valid(
                     'Multiple concurrent "listen" sessions are not supported'
                 )
-            host = listen("host", "127.0.0.1")
+            localhost = sockets.get_default_localhost()
+            host = listen("host", localhost)
             port = listen("port", int)
             adapter.access_token = None
             self.restart_requested = request("restart", False)
             host, port = servers.serve(host, port)
         else:
             if not servers.is_serving():
-                servers.serve()
-            host, port = servers.listener.getsockname()
+                servers.serve(host)
+            host, port = servers.listener.getsockname()[:2]
 
         # There are four distinct possibilities here.
         #
@@ -718,7 +720,7 @@ def report_sockets(self):
             }
             for listener in [clients.listener, launchers.listener, servers.listener]
             if listener is not None
-            for (host, port) in [listener.getsockname()]
+            for (host, port) in [listener.getsockname()[:2]]
         ]
         self.channel.send_event(
             "debugpySockets",
@@ -759,10 +761,11 @@ def notify_of_subprocess(self, conn):
         if "connect" not in body:
             body["connect"] = {}
         if "host" not in body["connect"]:
-            body["connect"]["host"] = host if host is not None else "127.0.0.1"
+            localhost = sockets.get_default_localhost()
+            body["connect"]["host"] = host if host is not None else localhost
         if "port" not in body["connect"]:
             if port is None:
-                _, port = listener.getsockname()
+                _, port = listener.getsockname()[:2]
             body["connect"]["port"] = port
 
         if self.capabilities["supportsStartDebuggingRequest"]:
@@ -779,7 +782,7 @@ def serve(host, port):
     global listener
     listener = sockets.serve("Client", Client, host, port)
     sessions.report_sockets()
-    return listener.getsockname()
+    return listener.getsockname()[:2]
 
 
 def stop_serving():
diff --git a/src/debugpy/adapter/launchers.py b/src/debugpy/adapter/launchers.py
index 38a990d76..6361ff8aa 100644
--- a/src/debugpy/adapter/launchers.py
+++ b/src/debugpy/adapter/launchers.py
@@ -89,7 +89,7 @@ def spawn_debuggee(
 
     arguments = dict(start_request.arguments)
     if not session.no_debug:
-        _, arguments["port"] = servers.listener.getsockname()
+        _, arguments["port"] = servers.listener.getsockname()[:2]
         arguments["adapterAccessToken"] = adapter.access_token
 
     def on_launcher_connected(sock):
@@ -108,10 +108,11 @@ def on_launcher_connected(sock):
     sessions.report_sockets()
 
     try:
-        launcher_host, launcher_port = listener.getsockname()
+        launcher_host, launcher_port = listener.getsockname()[:2]
+        localhost = sockets.get_default_localhost()
         launcher_addr = (
             launcher_port
-            if launcher_host == "127.0.0.1"
+            if launcher_host == localhost
             else f"{launcher_host}:{launcher_port}"
         )
         cmdline += [str(launcher_addr), "--"]
diff --git a/src/debugpy/adapter/servers.py b/src/debugpy/adapter/servers.py
index 307a2ce62..aa31a332c 100644
--- a/src/debugpy/adapter/servers.py
+++ b/src/debugpy/adapter/servers.py
@@ -395,7 +395,7 @@ def serve(host="127.0.0.1", port=0):
     global listener
     listener = sockets.serve("Server", Connection, host, port)
     sessions.report_sockets()
-    return listener.getsockname()
+    return listener.getsockname()[:2]
 
 
 def is_serving():
@@ -475,7 +475,7 @@ def dont_wait_for_first_connection():
 
 
 def inject(pid, debugpy_args, on_output):
-    host, port = listener.getsockname()
+    host, port = listener.getsockname()[:2]
 
     cmdline = [
         sys.executable,
diff --git a/src/debugpy/common/sockets.py b/src/debugpy/common/sockets.py
index ffcef80f6..2d3e39e9d 100644
--- a/src/debugpy/common/sockets.py
+++ b/src/debugpy/common/sockets.py
@@ -9,18 +9,60 @@
 from debugpy.common import log
 from debugpy.common.util import hide_thread_from_debugger
 
+def can_bind_ipv4_localhost():
+    """Check if we can bind to IPv4 localhost."""
+    try:
+        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        # Try to bind to IPv4 localhost on port 0 (any available port)
+        sock.bind(('127.0.0.1', 0))
+        sock.close()
+        return True
+    except (socket.error, OSError):
+        return False
+
+def can_bind_ipv6_localhost():
+    """Check if we can bind to IPv6 localhost."""
+    try:
+        sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
+        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        # Try to bind to IPv6 localhost on port 0 (any available port)
+        sock.bind(('::1', 0))
+        sock.close()
+        return True
+    except (socket.error, OSError, AttributeError):
+        return False
+
+def get_default_localhost():
+    """
+    Get the default localhost address.
+    Defaults to IPv4 '127.0.0.1', but falls back to IPv6 '::1' if IPv4 is unavailable.
+    """
+    # First try IPv4 (preferred default)
+    if can_bind_ipv4_localhost():
+        return '127.0.0.1'
+
+    # Fall back to IPv6 if IPv4 is not available
+    if can_bind_ipv6_localhost():
+        return '::1'
+    
+    # If neither works, still return IPv4 as a last resort
+    # (this is a very unusual situation)
+    return '127.0.0.1'
+
 
 def create_server(host, port=0, backlog=socket.SOMAXCONN, timeout=None):
     """Return a local server socket listening on the given port."""
 
     assert backlog > 0
     if host is None:
-        host = "127.0.0.1"
+        host = get_default_localhost()
     if port is None:
         port = 0
+    ipv6 = True if host.count(":") > 1 else False
 
     try:
-        server = _new_sock()
+        server = _new_sock(ipv6)
         if port != 0:
             # If binding to a specific port, make sure that the user doesn't have
             # to wait until the OS times out the socket to be able to use that port
@@ -42,13 +84,14 @@ def create_server(host, port=0, backlog=socket.SOMAXCONN, timeout=None):
     return server
 
 
-def create_client():
+def create_client(ipv6 = False):
     """Return a client socket that may be connected to a remote address."""
-    return _new_sock()
+    return _new_sock(ipv6)
 
 
-def _new_sock():
-    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
+def _new_sock(ipv6 = False):
+    address_family = socket.AF_INET6 if ipv6 else socket.AF_INET
+    sock = socket.socket(address_family, socket.SOCK_STREAM, socket.IPPROTO_TCP)
 
     # Set TCP keepalive on an open socket.
     # It activates after 1 second (TCP_KEEPIDLE,) of idleness,
@@ -102,13 +145,14 @@ def serve(name, handler, host, port=0, backlog=socket.SOMAXCONN, timeout=None):
         log.reraise_exception(
             "Error listening for incoming {0} connections on {1}:{2}:", name, host, port
         )
-    host, port = listener.getsockname()
+    host, port = listener.getsockname()[:2]
     log.info("Listening for incoming {0} connections on {1}:{2}...", name, host, port)
 
     def accept_worker():
         while True:
             try:
-                sock, (other_host, other_port) = listener.accept()
+                sock, address = listener.accept()
+                other_host, other_port = address[:2]
             except (OSError, socket.error):
                 # Listener socket has been closed.
                 break
diff --git a/src/debugpy/launcher/__init__.py b/src/debugpy/launcher/__init__.py
index a6e0934f1..a89f190f3 100644
--- a/src/debugpy/launcher/__init__.py
+++ b/src/debugpy/launcher/__init__.py
@@ -23,7 +23,8 @@ def connect(host, port):
 
     log.info("Connecting to adapter at {0}:{1}", host, port)
 
-    sock = sockets.create_client()
+    ipv6 = True if host.count(":") > 1 else False
+    sock = sockets.create_client(ipv6)
     sock.connect((host, port))
     adapter_host = host
 
diff --git a/src/debugpy/launcher/__main__.py b/src/debugpy/launcher/__main__.py
index cff18b5f1..7e17d4da8 100644
--- a/src/debugpy/launcher/__main__.py
+++ b/src/debugpy/launcher/__main__.py
@@ -14,7 +14,7 @@
 
 def main():
     from debugpy import launcher
-    from debugpy.common import log
+    from debugpy.common import log, sockets
     from debugpy.launcher import debuggee
 
     log.to_file(prefix="debugpy.launcher")
@@ -38,9 +38,10 @@ def main():
     # The first argument specifies the host/port on which the adapter is waiting
     # for launcher to connect. It's either host:port, or just port.
     adapter = launcher_argv[0]
-    host, sep, port = adapter.partition(":")
+    host, sep, port = adapter.rpartition(":")
+    host.strip("[]")
     if not sep:
-        host = "127.0.0.1"
+        host = sockets.get_default_localhost()
         port = adapter
     port = int(port)
 
diff --git a/src/debugpy/server/api.py b/src/debugpy/server/api.py
index 4b8cf9c54..fb76641bd 100644
--- a/src/debugpy/server/api.py
+++ b/src/debugpy/server/api.py
@@ -100,7 +100,8 @@ def debug(address, **kwargs):
             _, port = address
         except Exception:
             port = address
-            address = ("127.0.0.1", port)
+            localhost = sockets.get_default_localhost()
+            address = (localhost, port)
         try:
             port.__index__()  # ensure it's int-like
         except Exception:
@@ -143,8 +144,8 @@ def listen(address, settrace_kwargs, in_process_debug_adapter=False):
         # Multiple calls to listen() cause the debuggee to hang
         raise RuntimeError("debugpy.listen() has already been called on this process")
 
+    host, port = address
     if in_process_debug_adapter:
-        host, port = address
         log.info("Listening: pydevd without debugpy adapter: {0}:{1}", host, port)
         settrace_kwargs["patch_multiprocessing"] = False
         _settrace(
@@ -161,13 +162,14 @@ def listen(address, settrace_kwargs, in_process_debug_adapter=False):
     server_access_token = codecs.encode(os.urandom(32), "hex").decode("ascii")
 
     try:
-        endpoints_listener = sockets.create_server("127.0.0.1", 0, timeout=30)
+        localhost = sockets.get_default_localhost()
+        endpoints_listener = sockets.create_server(localhost, 0, timeout=30)
     except Exception as exc:
         log.swallow_exception("Can't listen for adapter endpoints:")
         raise RuntimeError("can't listen for adapter endpoints: " + str(exc))
 
     try:
-        endpoints_host, endpoints_port = endpoints_listener.getsockname()
+        endpoints_host, endpoints_port = endpoints_listener.getsockname()[:2]
         log.info(
             "Waiting for adapter endpoints on {0}:{1}...",
             endpoints_host,
diff --git a/src/debugpy/server/cli.py b/src/debugpy/server/cli.py
index 5e0520da8..a64f515aa 100644
--- a/src/debugpy/server/cli.py
+++ b/src/debugpy/server/cli.py
@@ -20,7 +20,7 @@
 
 import debugpy
 import debugpy.server
-from debugpy.common import log
+from debugpy.common import log, sockets
 from debugpy.server import api
 
 
@@ -104,9 +104,10 @@ def do(arg, it):
 
         # It's either host:port, or just port.
         value = next(it)
-        host, sep, port = value.partition(":")
+        host, sep, port = value.rpartition(":")
+        host = host.strip("[]")
         if not sep:
-            host = "127.0.0.1"
+            host = sockets.get_default_localhost()
             port = value
         try:
             port = int(port)
diff --git a/tests/debug/comms.py b/tests/debug/comms.py
index e690aceb3..0ffb3c5a3 100644
--- a/tests/debug/comms.py
+++ b/tests/debug/comms.py
@@ -25,7 +25,7 @@ def __str__(self):
 
     def listen(self):
         self._server_socket = sockets.create_server("127.0.0.1", 0, self.TIMEOUT)
-        _, self.port = self._server_socket.getsockname()
+        _, self.port = self._server_socket.getsockname()[:2]
         self._server_socket.listen(0)
 
         def accept_worker():
diff --git a/tests/debug/session.py b/tests/debug/session.py
index 3a821f5bc..8e319848c 100644
--- a/tests/debug/session.py
+++ b/tests/debug/session.py
@@ -464,7 +464,8 @@ def connect_to_adapter(self, address):
 
         self.expected_adapter_sockets["client"]["port"] = port
 
-        sock = sockets.create_client()
+        ipv6 = True if host.count(":") > 1 else False
+        sock = sockets.create_client(ipv6)
         sock.connect(address)
 
         stream = messaging.JsonIOStream.from_socket(sock, name=self.adapter_id)
diff --git a/tests/debugpy/server/test_cli.py b/tests/debugpy/server/test_cli.py
index a098cda8b..9b64ee0e5 100644
--- a/tests/debugpy/server/test_cli.py
+++ b/tests/debugpy/server/test_cli.py
@@ -15,7 +15,6 @@
 from debugpy.common import log
 from tests.patterns import some
 
-
 @pytest.fixture
 def cli(pyfile):
     @pyfile
@@ -89,7 +88,7 @@ def parse(args):
 # Test a combination of command line switches
 @pytest.mark.parametrize("target_kind", ["file", "module", "code"])
 @pytest.mark.parametrize("mode", ["listen", "connect"])
-@pytest.mark.parametrize("address", ["8888", "localhost:8888"])
+@pytest.mark.parametrize("address", ["8888", "localhost:8888", "[::1]:8888"])
 @pytest.mark.parametrize("wait_for_client", ["", "wait_for_client"])
 @pytest.mark.parametrize("script_args", ["", "script_args"])
 def test_targets(cli, target_kind, mode, address, wait_for_client, script_args):
@@ -101,7 +100,8 @@ def test_targets(cli, target_kind, mode, address, wait_for_client, script_args):
 
     args = ["--" + mode, address]
 
-    host, sep, port = address.partition(":")
+    host, sep, port = address.rpartition(":")
+    host = host.strip("[]")
     if sep:
         expected_options["address"] = (host, int(port))
     else:
diff --git a/tests/debugpy/test_attach.py b/tests/debugpy/test_attach.py
index c973b09bb..a2cb2fa1e 100644
--- a/tests/debugpy/test_attach.py
+++ b/tests/debugpy/test_attach.py
@@ -14,8 +14,9 @@
 @pytest.mark.parametrize("stop_method", ["breakpoint", "pause"])
 @pytest.mark.skipif(IS_PY312_OR_GREATER, reason="Flakey test on 312 and higher")
 @pytest.mark.parametrize("is_client_connected", ["is_client_connected", ""])
+@pytest.mark.parametrize("host", ["127.0.0.1", "::1"])
 @pytest.mark.parametrize("wait_for_client", ["wait_for_client", pytest.param("", marks=pytest.mark.skipif(sys.platform.startswith("darwin"), reason="Flakey test on Mac"))])
-def test_attach_api(pyfile, wait_for_client, is_client_connected, stop_method):
+def test_attach_api(pyfile, host, wait_for_client, is_client_connected, stop_method):
     @pyfile
     def code_to_debug():
         import debuggee
@@ -58,7 +59,8 @@ def code_to_debug():
                 time.sleep(0.1)
 
     with debug.Session() as session:
-        host, port = runners.attach_connect.host, runners.attach_connect.port
+        host = runners.attach_connect.host if host == "127.0.0.1" else host
+        port = runners.attach_connect.port
         session.config.update({"connect": {"host": host, "port": port}})
 
         backchannel = session.open_backchannel()
@@ -102,7 +104,8 @@ def code_to_debug():
 
         session.request_continue()
 
-def test_multiple_listen_raises_exception(pyfile):
+@pytest.mark.parametrize("host", ["127.0.0.1", "::1"])
+def test_multiple_listen_raises_exception(pyfile, host):
     @pyfile
     def code_to_debug():
         import debuggee
@@ -124,7 +127,8 @@ def code_to_debug():
         debugpy.breakpoint()
         print("break")  # @breakpoint
 
-    host, port = runners.attach_connect.host, runners.attach_connect.port
+    host = runners.attach_connect.host if host == "127.0.0.1" else host
+    port = runners.attach_connect.port
     with debug.Session() as session:
         backchannel = session.open_backchannel()
         session.spawn_debuggee(
@@ -147,7 +151,6 @@ def code_to_debug():
         assert backchannel.receive() == "listen_exception"
         session.request_continue()
 
-
 @pytest.mark.parametrize("run", runners.all_attach_connect)
 def test_reattach(pyfile, target, run):
     @pyfile
@@ -265,7 +268,8 @@ def before_request(command, arguments):
         session2.request_continue()
 
 
-def test_cancel_wait(pyfile):
+@pytest.mark.parametrize("host", ["127.0.0.1", "::1"])
+def test_cancel_wait(pyfile, host):
     @pyfile
     def code_to_debug():
         import debugpy
@@ -287,7 +291,8 @@ def cancel():
         backchannel.send("exit")
 
     with debug.Session() as session:
-        host, port = runners.attach_connect.host, runners.attach_connect.port
+        host = runners.attach_connect.host if host == "127.0.0.1" else host
+        port = runners.attach_connect.port
         session.config.update({"connect": {"host": host, "port": port}})
         session.expected_exit_code = None
 

From 6ab314d30166d43fd10d4462923c8690d1dbeabd Mon Sep 17 00:00:00 2001
From: Drake Aiman <daiman776@gmail.com>
Date: Tue, 20 May 2025 09:19:47 -0700
Subject: [PATCH 2/5] address comments (part 1)

---
 src/debugpy/adapter/__main__.py  |  2 +-
 src/debugpy/adapter/clients.py   |  2 +-
 src/debugpy/common/sockets.py    | 17 ++++++++---------
 src/debugpy/launcher/__init__.py |  2 +-
 tests/debug/session.py           |  2 +-
 5 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/src/debugpy/adapter/__main__.py b/src/debugpy/adapter/__main__.py
index 43a7e5118..a6705c069 100644
--- a/src/debugpy/adapter/__main__.py
+++ b/src/debugpy/adapter/__main__.py
@@ -81,7 +81,7 @@ def main():
         )
 
         try:
-            ipv6 = True if localhost.count(":") > 1 else False
+            ipv6 = localhost.count(":") > 1
             sock = sockets.create_client(ipv6)
             try:
                 sock.settimeout(None)
diff --git a/src/debugpy/adapter/clients.py b/src/debugpy/adapter/clients.py
index 186c1ab6d..2b11c7402 100644
--- a/src/debugpy/adapter/clients.py
+++ b/src/debugpy/adapter/clients.py
@@ -762,7 +762,7 @@ def notify_of_subprocess(self, conn):
             body["connect"] = {}
         if "host" not in body["connect"]:
             localhost = sockets.get_default_localhost()
-            body["connect"]["host"] = host if host is not None else localhost
+            body["connect"]["host"] = host or localhost
         if "port" not in body["connect"]:
             if port is None:
                 _, port = listener.getsockname()[:2]
diff --git a/src/debugpy/common/sockets.py b/src/debugpy/common/sockets.py
index 2d3e39e9d..ee19f8278 100644
--- a/src/debugpy/common/sockets.py
+++ b/src/debugpy/common/sockets.py
@@ -15,7 +15,7 @@ def can_bind_ipv4_localhost():
         sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
         # Try to bind to IPv4 localhost on port 0 (any available port)
-        sock.bind(('127.0.0.1', 0))
+        sock.bind(("127.0.0.1", 0))
         sock.close()
         return True
     except (socket.error, OSError):
@@ -27,28 +27,27 @@ def can_bind_ipv6_localhost():
         sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
         sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
         # Try to bind to IPv6 localhost on port 0 (any available port)
-        sock.bind(('::1', 0))
+        sock.bind(("::1", 0))
         sock.close()
         return True
     except (socket.error, OSError, AttributeError):
         return False
 
 def get_default_localhost():
-    """
-    Get the default localhost address.
+    """Get the default localhost address.
     Defaults to IPv4 '127.0.0.1', but falls back to IPv6 '::1' if IPv4 is unavailable.
     """
     # First try IPv4 (preferred default)
     if can_bind_ipv4_localhost():
-        return '127.0.0.1'
+        return "127.0.0.1"
 
     # Fall back to IPv6 if IPv4 is not available
     if can_bind_ipv6_localhost():
-        return '::1'
+        return "::1"
     
     # If neither works, still return IPv4 as a last resort
     # (this is a very unusual situation)
-    return '127.0.0.1'
+    return "127.0.0.1"
 
 
 def create_server(host, port=0, backlog=socket.SOMAXCONN, timeout=None):
@@ -59,7 +58,7 @@ def create_server(host, port=0, backlog=socket.SOMAXCONN, timeout=None):
         host = get_default_localhost()
     if port is None:
         port = 0
-    ipv6 = True if host.count(":") > 1 else False
+    ipv6 = host.count(":") > 1
 
     try:
         server = _new_sock(ipv6)
@@ -84,7 +83,7 @@ def create_server(host, port=0, backlog=socket.SOMAXCONN, timeout=None):
     return server
 
 
-def create_client(ipv6 = False):
+def create_client(ipv6=False):
     """Return a client socket that may be connected to a remote address."""
     return _new_sock(ipv6)
 
diff --git a/src/debugpy/launcher/__init__.py b/src/debugpy/launcher/__init__.py
index a89f190f3..677740262 100644
--- a/src/debugpy/launcher/__init__.py
+++ b/src/debugpy/launcher/__init__.py
@@ -23,7 +23,7 @@ def connect(host, port):
 
     log.info("Connecting to adapter at {0}:{1}", host, port)
 
-    ipv6 = True if host.count(":") > 1 else False
+    ipv6 = host.count(":") > 1
     sock = sockets.create_client(ipv6)
     sock.connect((host, port))
     adapter_host = host
diff --git a/tests/debug/session.py b/tests/debug/session.py
index 8e319848c..05abea62a 100644
--- a/tests/debug/session.py
+++ b/tests/debug/session.py
@@ -464,7 +464,7 @@ def connect_to_adapter(self, address):
 
         self.expected_adapter_sockets["client"]["port"] = port
 
-        ipv6 = True if host.count(":") > 1 else False
+        ipv6 = host.count(":") > 1
         sock = sockets.create_client(ipv6)
         sock.connect(address)
 

From f53cba25b3d72b039963b2b1a79343411f4b16aa Mon Sep 17 00:00:00 2001
From: Drake Aiman <daiman776@gmail.com>
Date: Wed, 21 May 2025 08:31:24 -0700
Subject: [PATCH 3/5] quick clean up of missed fix suggestion

---
 src/debugpy/common/sockets.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/debugpy/common/sockets.py b/src/debugpy/common/sockets.py
index ee19f8278..e694c2a71 100644
--- a/src/debugpy/common/sockets.py
+++ b/src/debugpy/common/sockets.py
@@ -88,7 +88,7 @@ def create_client(ipv6=False):
     return _new_sock(ipv6)
 
 
-def _new_sock(ipv6 = False):
+def _new_sock(ipv6=False):
     address_family = socket.AF_INET6 if ipv6 else socket.AF_INET
     sock = socket.socket(address_family, socket.SOCK_STREAM, socket.IPPROTO_TCP)
 

From 3ef28441edfc84ab3a2ff731693fd8505407befc Mon Sep 17 00:00:00 2001
From: Drake Aiman <daiman776@gmail.com>
Date: Wed, 21 May 2025 20:54:26 -0700
Subject: [PATCH 4/5] Fix misassigned default serving server address in adapter
 client

---
 src/debugpy/adapter/clients.py | 4 ++--
 src/debugpy/common/sockets.py  | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/debugpy/adapter/clients.py b/src/debugpy/adapter/clients.py
index 2b11c7402..917d0ae44 100644
--- a/src/debugpy/adapter/clients.py
+++ b/src/debugpy/adapter/clients.py
@@ -473,12 +473,12 @@ def attach_request(self, request):
                 '"processId" and "subProcessId" are mutually exclusive'
             )
 
+        localhost = sockets.get_default_localhost()
         if listen != ():
             if servers.is_serving():
                 raise request.isnt_valid(
                     'Multiple concurrent "listen" sessions are not supported'
                 )
-            localhost = sockets.get_default_localhost()
             host = listen("host", localhost)
             port = listen("port", int)
             adapter.access_token = None
@@ -486,7 +486,7 @@ def attach_request(self, request):
             host, port = servers.serve(host, port)
         else:
             if not servers.is_serving():
-                servers.serve(host)
+                servers.serve(localhost)
             host, port = servers.listener.getsockname()[:2]
 
         # There are four distinct possibilities here.
diff --git a/src/debugpy/common/sockets.py b/src/debugpy/common/sockets.py
index e694c2a71..0b1c8fadc 100644
--- a/src/debugpy/common/sockets.py
+++ b/src/debugpy/common/sockets.py
@@ -18,7 +18,7 @@ def can_bind_ipv4_localhost():
         sock.bind(("127.0.0.1", 0))
         sock.close()
         return True
-    except (socket.error, OSError):
+    except (socket.error, OSError, AttributeError):
         return False
 
 def can_bind_ipv6_localhost():

From 79860c58bef54c4b6a4f0c823794d6828b284180 Mon Sep 17 00:00:00 2001
From: Drake Aiman <daiman776@gmail.com>
Date: Thu, 22 May 2025 11:55:35 -0700
Subject: [PATCH 5/5] add wrapper method to get host and port from`getsockname`

---
 src/debugpy/adapter/clients.py   | 12 ++++++------
 src/debugpy/adapter/launchers.py |  4 ++--
 src/debugpy/adapter/servers.py   |  4 ++--
 src/debugpy/common/sockets.py    | 11 ++++++++++-
 src/debugpy/server/api.py        |  2 +-
 tests/debug/comms.py             |  2 +-
 6 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/src/debugpy/adapter/clients.py b/src/debugpy/adapter/clients.py
index 917d0ae44..4931b70c7 100644
--- a/src/debugpy/adapter/clients.py
+++ b/src/debugpy/adapter/clients.py
@@ -487,7 +487,7 @@ def attach_request(self, request):
         else:
             if not servers.is_serving():
                 servers.serve(localhost)
-            host, port = servers.listener.getsockname()[:2]
+            host, port = sockets.get_address(servers.listener)
 
         # There are four distinct possibilities here.
         #
@@ -712,7 +712,7 @@ def disconnect(self):
         super().disconnect()
 
     def report_sockets(self):
-        sockets = [
+        socks = [
             {
                 "host": host,
                 "port": port,
@@ -720,12 +720,12 @@ def report_sockets(self):
             }
             for listener in [clients.listener, launchers.listener, servers.listener]
             if listener is not None
-            for (host, port) in [listener.getsockname()[:2]]
+            for (host, port) in [sockets.get_address(listener)]
         ]
         self.channel.send_event(
             "debugpySockets",
             {
-                "sockets": sockets
+                "sockets": socks
             },
         )
 
@@ -765,7 +765,7 @@ def notify_of_subprocess(self, conn):
             body["connect"]["host"] = host or localhost
         if "port" not in body["connect"]:
             if port is None:
-                _, port = listener.getsockname()[:2]
+                _, port = sockets.get_address(listener)
             body["connect"]["port"] = port
 
         if self.capabilities["supportsStartDebuggingRequest"]:
@@ -782,7 +782,7 @@ def serve(host, port):
     global listener
     listener = sockets.serve("Client", Client, host, port)
     sessions.report_sockets()
-    return listener.getsockname()[:2]
+    return sockets.get_address(listener)
 
 
 def stop_serving():
diff --git a/src/debugpy/adapter/launchers.py b/src/debugpy/adapter/launchers.py
index 6361ff8aa..62f948817 100644
--- a/src/debugpy/adapter/launchers.py
+++ b/src/debugpy/adapter/launchers.py
@@ -89,7 +89,7 @@ def spawn_debuggee(
 
     arguments = dict(start_request.arguments)
     if not session.no_debug:
-        _, arguments["port"] = servers.listener.getsockname()[:2]
+        _, arguments["port"] = sockets.get_address(servers.listener)
         arguments["adapterAccessToken"] = adapter.access_token
 
     def on_launcher_connected(sock):
@@ -108,7 +108,7 @@ def on_launcher_connected(sock):
     sessions.report_sockets()
 
     try:
-        launcher_host, launcher_port = listener.getsockname()[:2]
+        launcher_host, launcher_port = sockets.get_address(listener)
         localhost = sockets.get_default_localhost()
         launcher_addr = (
             launcher_port
diff --git a/src/debugpy/adapter/servers.py b/src/debugpy/adapter/servers.py
index aa31a332c..0aede938f 100644
--- a/src/debugpy/adapter/servers.py
+++ b/src/debugpy/adapter/servers.py
@@ -395,7 +395,7 @@ def serve(host="127.0.0.1", port=0):
     global listener
     listener = sockets.serve("Server", Connection, host, port)
     sessions.report_sockets()
-    return listener.getsockname()[:2]
+    return sockets.get_address(listener)
 
 
 def is_serving():
@@ -475,7 +475,7 @@ def dont_wait_for_first_connection():
 
 
 def inject(pid, debugpy_args, on_output):
-    host, port = listener.getsockname()[:2]
+    host, port = sockets.get_address(listener)
 
     cmdline = [
         sys.executable,
diff --git a/src/debugpy/common/sockets.py b/src/debugpy/common/sockets.py
index 0b1c8fadc..47db4d89b 100644
--- a/src/debugpy/common/sockets.py
+++ b/src/debugpy/common/sockets.py
@@ -49,6 +49,15 @@ def get_default_localhost():
     # (this is a very unusual situation)
     return "127.0.0.1"
 
+def get_address(sock):
+    """Gets the socket address host and port."""
+    try:
+        host, port = sock.getsockname()[:2]
+    except Exception as exc:
+        log.swallow_exception("Failed to get socket address:")
+        raise RuntimeError(f"Failed to get socket address: {exc}") from exc
+
+    return host, port
 
 def create_server(host, port=0, backlog=socket.SOMAXCONN, timeout=None):
     """Return a local server socket listening on the given port."""
@@ -144,7 +153,7 @@ def serve(name, handler, host, port=0, backlog=socket.SOMAXCONN, timeout=None):
         log.reraise_exception(
             "Error listening for incoming {0} connections on {1}:{2}:", name, host, port
         )
-    host, port = listener.getsockname()[:2]
+    host, port = get_address(listener)
     log.info("Listening for incoming {0} connections on {1}:{2}...", name, host, port)
 
     def accept_worker():
diff --git a/src/debugpy/server/api.py b/src/debugpy/server/api.py
index fb76641bd..eb54ffed8 100644
--- a/src/debugpy/server/api.py
+++ b/src/debugpy/server/api.py
@@ -169,7 +169,7 @@ def listen(address, settrace_kwargs, in_process_debug_adapter=False):
         raise RuntimeError("can't listen for adapter endpoints: " + str(exc))
 
     try:
-        endpoints_host, endpoints_port = endpoints_listener.getsockname()[:2]
+        endpoints_host, endpoints_port = sockets.get_address(endpoints_listener)
         log.info(
             "Waiting for adapter endpoints on {0}:{1}...",
             endpoints_host,
diff --git a/tests/debug/comms.py b/tests/debug/comms.py
index 0ffb3c5a3..a46ad5ca5 100644
--- a/tests/debug/comms.py
+++ b/tests/debug/comms.py
@@ -25,7 +25,7 @@ def __str__(self):
 
     def listen(self):
         self._server_socket = sockets.create_server("127.0.0.1", 0, self.TIMEOUT)
-        _, self.port = self._server_socket.getsockname()[:2]
+        _, self.port = sockets.get_address(self._server_socket)
         self._server_socket.listen(0)
 
         def accept_worker():