http: fix unix domain socket use in https connects

- when h2/h3 eyeballing was involved, unix domain socket
  configurations were not honoured
- configuring --unix-socket will disable HTTP/3 as candidate for eyeballing
- combinatino of --unix-socket and --http3-only will fail during initialisation
- adding pytest test_11 to reproduce

Reported-by: Jelle van der Waa
Fixes #10633
Closes #10641

tests/tests-httpd/test_11_unix.py

@@ -0,0 +1,129 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#***************************************************************************
+#                                  _   _ ____  _
+#  Project                     ___| | | |  _ \| |
+#                             / __| | | | |_) | |
+#                            | (__| |_| |  _ <| |___
+#                             \___|\___/|_| \_\_____|
+#
+# Copyright (C) 2008 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at https://curl.se/docs/copyright.html.
+#
+# You may opt to use, copy, modify, merge, publish, distribute and/or sell
+# copies of the Software, and permit persons to whom the Software is
+# furnished to do so, under the terms of the COPYING file.
+#
+# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+# KIND, either express or implied.
+#
+# SPDX-License-Identifier: curl
+#
+###########################################################################
+#
+import logging
+import os
+import socket
+from threading import Thread
+import pytest
+
+from testenv import Env, CurlClient
+
+
+log = logging.getLogger(__name__)
+
+class UDSFaker:
+
+    def __init__(self, path):
+        self._uds_path = path
+        self._done = False
+
+    @property
+    def path(self):
+        return self._uds_path
+
+    def start(self):
+        def process(self):
+            self._socket.listen(1)
+            self._process()
+
+        try:
+            os.unlink(self._uds_path)
+        except OSError:
+            if os.path.exists(self._uds_path):
+                raise
+        self._socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
+        self._socket.bind(self._uds_path)
+        self._thread = Thread(target=process, daemon=True, args=[self])
+        self._thread.start()
+
+    def stop(self):
+        self._done = True
+        self._socket.close()
+
+    def _process(self):
+        while self._done is False:
+            try:
+                c, client_address = self._socket.accept()
+                try:
+                    data = c.recv(16)
+                    c.sendall("""HTTP/1.1 200 Ok
+Server: UdsFaker
+Content-Type: application/json
+Content-Length: 19
+
+{ "host": "faked" }""".encode())
+                finally:
+                    c.close()
+
+            except ConnectionAbortedError:
+                self._done = True
+
+
+
+@pytest.mark.skipif(condition=Env.setup_incomplete(),
+                    reason=f"missing: {Env.incomplete_reason()}")
+class TestUnix:
+
+    @pytest.fixture(scope="class")
+    def uds_faker(self, env: Env) -> UDSFaker:
+        uds_path = os.path.join(env.gen_dir, 'uds_11.sock')
+        faker = UDSFaker(path=uds_path)
+        faker.start()
+        yield faker
+        faker.stop()
+
+    # download http: via unix socket
+    def test_11_01_unix_connect_http(self, env: Env, httpd, uds_faker, repeat):
+        curl = CurlClient(env=env)
+        url = f'http://{env.domain1}:{env.http_port}/data.json'
+        r = curl.http_download(urls=[url], with_stats=True,
+                               extra_args=[
+                                 '--unix-socket', uds_faker.path,
+                               ])
+        assert r.exit_code == 0
+        r.check_stats(count=1, exp_status=200)
+
+    # download https: via unix socket
+    def test_11_02_unix_connect_http(self, env: Env, httpd, uds_faker, repeat):
+        curl = CurlClient(env=env)
+        url = f'https://{env.domain1}:{env.https_port}/data.json'
+        r = curl.http_download(urls=[url], with_stats=True,
+                               extra_args=[
+                                 '--unix-socket', uds_faker.path,
+                               ])
+        assert r.exit_code == 35  # CONNECT_ERROR (as faker is not TLS)
+
+    # download HTTP/3 via unix socket
+    def test_11_03_unix_connect_quic(self, env: Env, httpd, uds_faker, repeat):
+        curl = CurlClient(env=env)
+        url = f'https://{env.domain1}:{env.https_port}/data.json'
+        r = curl.http_download(urls=[url], with_stats=True,
+                               alpn_proto='h3',
+                               extra_args=[
+                                 '--unix-socket', uds_faker.path,
+                               ])
+        assert r.exit_code == 96  # QUIC CONNECT ERROR