Merge d3ae5688b4 into a06bb58679

README.md

@@ -777,6 +777,7 @@ If you fork the project on GitHub, you can run your fork's [build workflow](.git
                                     that do not support RFC 5746 secure
                                     renegotiation
     --no-check-certificates         Suppress HTTPS certificate validation
+    --proxy-no-check-certificates   Suppress HTTPS Proxy certificate validation
     --prefer-insecure               Use an unencrypted connection to retrieve
                                     information about the video (Currently
                                     supported only for YouTube)
@@ -882,6 +883,18 @@ If you fork the project on GitHub, you can run your fork's [build workflow](.git
                                     Password for client certificate private key,
                                     if encrypted. If not provided, and the key
                                     is encrypted, yt-dlp will ask interactively
+    --proxy-client-certificate CERTFILE
+                                    Path to client certificate file in PEM
+                                    format for HTTPS proxy. May include the
+                                    private key
+    --proxy-client-certificate-key KEYFILE
+                                    Path to private key file for client
+                                    certificate for HTTPS proxy
+    --proxy-client-certificate-password PASSWORD
+                                    Password for client certificate private key,
+                                    if encrypted, for HTTPS proxy. If not
+                                    provided, and the key is encrypted, yt-dlp
+                                    will ask interactively
 
 ## Post-Processing Options:
     -x, --extract-audio             Convert video files to audio-only files

test/test_http_proxy.py

@@ -19,6 +19,8 @@ from yt_dlp.dependencies import urllib3
 from yt_dlp.networking import Request
 from yt_dlp.networking.exceptions import HTTPError, ProxyError, SSLError
 
+MTLS_CERT_DIR = os.path.join(TEST_DIR, 'testdata', 'certificate')
+
 
 class HTTPProxyAuthMixin:
 
@@ -135,6 +137,35 @@ class HTTPSProxyHandler(HTTPProxyHandler):
         super().__init__(request, *args, **kwargs)
 
 
+class MTLSHTTPSProxyHandler(HTTPProxyHandler):
+    def __init__(self, request, *args, **kwargs):
+        certfn = os.path.join(TEST_DIR, 'testcert.pem')
+        cacertfn = os.path.join(MTLS_CERT_DIR, 'ca.crt')
+        sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
+        sslctx.verify_mode = ssl.CERT_REQUIRED
+        sslctx.load_verify_locations(cafile=cacertfn)
+        sslctx.load_cert_chain(certfn, None)
+        if isinstance(request, ssl.SSLSocket):
+            request = SSLTransport(request, ssl_context=sslctx, server_side=True)
+        else:
+            request = sslctx.wrap_socket(request, server_side=True)
+        super().__init__(request, *args, **kwargs)
+
+
+class LegacyHTTPSProxyHandler(HTTPProxyHandler):
+    def __init__(self, request, *args, **kwargs):
+        certfn = os.path.join(TEST_DIR, 'testcert.pem')
+        sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
+        sslctx.maximum_version = ssl.TLSVersion.TLSv1_2
+        sslctx.set_ciphers('SHA1:AESCCM:aDSS:eNULL:aNULL')
+        sslctx.load_cert_chain(certfn, None)
+        if isinstance(request, ssl.SSLSocket):
+            request = SSLTransport(request, ssl_context=sslctx, server_side=True)
+        else:
+            request = sslctx.wrap_socket(request, server_side=True)
+        super().__init__(request, *args, **kwargs)
+
+
 class HTTPConnectProxyHandler(BaseHTTPRequestHandler, HTTPProxyAuthMixin):
     protocol_version = 'HTTP/1.1'
     default_request_version = 'HTTP/1.1'
@@ -178,6 +209,39 @@ class HTTPSConnectProxyHandler(HTTPConnectProxyHandler):
         self.server.close_request(self._original_request)
 
 
+class MTLSHTTPSConnectProxyHandler(HTTPConnectProxyHandler):
+    def __init__(self, request, *args, **kwargs):
+        certfn = os.path.join(TEST_DIR, 'testcert.pem')
+        cacertfn = os.path.join(MTLS_CERT_DIR, 'ca.crt')
+        sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
+        sslctx.verify_mode = ssl.CERT_REQUIRED
+        sslctx.load_verify_locations(cafile=cacertfn)
+        sslctx.load_cert_chain(certfn, None)
+        request = sslctx.wrap_socket(request, server_side=True)
+        self._original_request = request
+        super().__init__(request, *args, **kwargs)
+
+    def do_CONNECT(self):
+        super().do_CONNECT()
+        self.server.close_request(self._original_request)
+
+
+class LegacyHTTPSConnectProxyHandler(HTTPConnectProxyHandler):
+    def __init__(self, request, *args, **kwargs):
+        certfn = os.path.join(TEST_DIR, 'testcert.pem')
+        sslctx = ssl.SSLContext(ssl.PROTOCOL_TLS_SERVER)
+        sslctx.maximum_version = ssl.TLSVersion.TLSv1_2
+        sslctx.set_ciphers('SHA1:AESCCM:aDSS:eNULL:aNULL')
+        sslctx.load_cert_chain(certfn, None)
+        request = sslctx.wrap_socket(request, server_side=True)
+        self._original_request = request
+        super().__init__(request, *args, **kwargs)
+
+    def do_CONNECT(self):
+        super().do_CONNECT()
+        self.server.close_request(self._original_request)
+
+
 @contextlib.contextmanager
 def proxy_server(proxy_server_class, request_handler, bind_ip=None, **proxy_server_kwargs):
     server = server_thread = None
@@ -285,7 +349,7 @@ class TestHTTPProxy:
     @pytest.mark.skip_handler('Urllib', 'urllib does not support https proxies')
     def test_https(self, handler, ctx):
         with ctx.http_server(HTTPSProxyHandler) as server_address:
-            with handler(verify=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+            with handler(proxy_verify=False, verify=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
                 proxy_info = ctx.proxy_info_request(rh)
                 assert proxy_info['proxy'] == server_address
                 assert proxy_info['connect'] is False
@@ -294,10 +358,64 @@ class TestHTTPProxy:
     @pytest.mark.skip_handler('Urllib', 'urllib does not support https proxies')
     def test_https_verify_failed(self, handler, ctx):
         with ctx.http_server(HTTPSProxyHandler) as server_address:
-            with handler(verify=True, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
-                # Accept SSLError as may not be feasible to tell if it is proxy or request error.
-                # note: if request proto also does ssl verification, this may also be the error of the request.
-                # Until we can support passing custom cacerts to handlers, we cannot properly test this for all cases.
+            with handler(proxy_verify=True, verify=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+                # Accept both ProxyError and SSLError as may not be feasible to tell if it is proxy or request error.
+                with pytest.raises((ProxyError, SSLError)):
+                    ctx.proxy_info_request(rh)
+
+    @pytest.mark.skip_handler('Urllib', 'urllib does not support https proxies')
+    @pytest.mark.skip_handler('CurlCFFI', 'legacy_ssl ignored by CurlCFFI')
+    def test_https_legacy_ssl_support(self, handler, ctx):
+        with ctx.http_server(LegacyHTTPSProxyHandler) as server_address:
+            with handler(proxy_verify=False, verify=False, proxy_legacy_ssl_support=True, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+                proxy_info = ctx.proxy_info_request(rh)
+                assert proxy_info['proxy'] == server_address
+                assert proxy_info['connect'] is False
+                assert 'Proxy-Authorization' not in proxy_info['headers']
+
+            with handler(proxy_verify=False, verify=False, proxy_legacy_ssl_support=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+                with pytest.raises((ProxyError, SSLError)):
+                    ctx.proxy_info_request(rh)
+
+    @pytest.mark.skip_handler('Urllib', 'urllib does not support https proxies')
+    @pytest.mark.parametrize('proxy_client_cert', [
+        {'client_certificate': os.path.join(MTLS_CERT_DIR, 'clientwithkey.crt')},
+        {
+            'client_certificate': os.path.join(MTLS_CERT_DIR, 'client.crt'),
+            'client_certificate_key': os.path.join(MTLS_CERT_DIR, 'client.key'),
+        },
+        {
+            'client_certificate': os.path.join(MTLS_CERT_DIR, 'clientwithencryptedkey.crt'),
+            'client_certificate_password': 'foobar',
+        },
+        {
+            'client_certificate': os.path.join(MTLS_CERT_DIR, 'client.crt'),
+            'client_certificate_key': os.path.join(MTLS_CERT_DIR, 'clientencrypted.key'),
+            'client_certificate_password': 'foobar',
+        },
+    ], ids=['combined_nopass', 'nocombined_nopass', 'combined_pass', 'nocombined_pass'])
+    def test_https_mtls(self, handler, ctx, proxy_client_cert):
+        with ctx.http_server(MTLSHTTPSProxyHandler) as server_address:
+            with handler(
+                proxy_verify=False,
+                verify=False,
+                proxy_client_cert=proxy_client_cert,
+                proxies={ctx.REQUEST_PROTO: f'https://{server_address}'},
+            ) as rh:
+                proxy_info = ctx.proxy_info_request(rh)
+                assert proxy_info['proxy'] == server_address
+                assert proxy_info['connect'] is False
+                assert 'Proxy-Authorization' not in proxy_info['headers']
+
+    @pytest.mark.skip_handler('Urllib', 'urllib does not support https proxies')
+    def test_https_mtls_error(self, handler, ctx):
+        with ctx.http_server(MTLSHTTPSProxyHandler) as server_address:
+            with handler(
+                proxy_verify=False,
+                verify=False,
+                proxy_client_cert=None,
+                proxies={ctx.REQUEST_PROTO: f'https://{server_address}'},
+            ) as rh:
                 with pytest.raises((ProxyError, SSLError)):
                     ctx.proxy_info_request(rh)
 
@@ -331,10 +449,6 @@ class TestHTTPConnectProxy:
                 assert proxy_info['proxy'] == server_address
                 assert 'Proxy-Authorization' in proxy_info['headers']
 
-    @pytest.mark.skip_handler(
-        'Requests',
-        'bug in urllib3 causes unclosed socket: https://github.com/urllib3/urllib3/issues/3374',
-    )
     def test_http_connect_bad_auth(self, handler, ctx):
         with ctx.http_server(HTTPConnectProxyHandler, username='test', password='test') as server_address:
             with handler(verify=False, proxies={ctx.REQUEST_PROTO: f'http://test:bad@{server_address}'}) as rh:
@@ -355,7 +469,7 @@ class TestHTTPConnectProxy:
     @pytest.mark.skipif(urllib3 is None, reason='requires urllib3 to test')
     def test_https_connect_proxy(self, handler, ctx):
         with ctx.http_server(HTTPSConnectProxyHandler) as server_address:
-            with handler(verify=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+            with handler(proxy_verify=False, verify=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
                 proxy_info = ctx.proxy_info_request(rh)
                 assert proxy_info['proxy'] == server_address
                 assert proxy_info['connect'] is True
@@ -364,17 +478,71 @@ class TestHTTPConnectProxy:
     @pytest.mark.skipif(urllib3 is None, reason='requires urllib3 to test')
     def test_https_connect_verify_failed(self, handler, ctx):
         with ctx.http_server(HTTPSConnectProxyHandler) as server_address:
-            with handler(verify=True, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
-                # Accept SSLError as may not be feasible to tell if it is proxy or request error.
-                # note: if request proto also does ssl verification, this may also be the error of the request.
-                # Until we can support passing custom cacerts to handlers, we cannot properly test this for all cases.
+            with handler(proxy_verify=True, verify=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+                # Accept both ProxyError and SSLError as may not be feasible to tell if it is proxy or request error.
                 with pytest.raises((ProxyError, SSLError)):
                     ctx.proxy_info_request(rh)
 
     @pytest.mark.skipif(urllib3 is None, reason='requires urllib3 to test')
     def test_https_connect_proxy_auth(self, handler, ctx):
         with ctx.http_server(HTTPSConnectProxyHandler, username='test', password='test') as server_address:
-            with handler(verify=False, proxies={ctx.REQUEST_PROTO: f'https://test:test@{server_address}'}) as rh:
+            with handler(proxy_verify=False, verify=False, proxies={ctx.REQUEST_PROTO: f'https://test:test@{server_address}'}) as rh:
                 proxy_info = ctx.proxy_info_request(rh)
                 assert proxy_info['proxy'] == server_address
                 assert 'Proxy-Authorization' in proxy_info['headers']
+
+    @pytest.mark.skipif(urllib3 is None, reason='requires urllib3 to test')
+    @pytest.mark.parametrize('proxy_client_cert', [
+        {'client_certificate': os.path.join(MTLS_CERT_DIR, 'clientwithkey.crt')},
+        {
+            'client_certificate': os.path.join(MTLS_CERT_DIR, 'client.crt'),
+            'client_certificate_key': os.path.join(MTLS_CERT_DIR, 'client.key'),
+        },
+        {
+            'client_certificate': os.path.join(MTLS_CERT_DIR, 'clientwithencryptedkey.crt'),
+            'client_certificate_password': 'foobar',
+        },
+        {
+            'client_certificate': os.path.join(MTLS_CERT_DIR, 'client.crt'),
+            'client_certificate_key': os.path.join(MTLS_CERT_DIR, 'clientencrypted.key'),
+            'client_certificate_password': 'foobar',
+        },
+    ], ids=['combined_nopass', 'nocombined_nopass', 'combined_pass', 'nocombined_pass'])
+    def test_https_connect_mtls(self, handler, ctx, proxy_client_cert):
+        with ctx.http_server(MTLSHTTPSConnectProxyHandler) as server_address:
+            with handler(
+                proxy_verify=False,
+                verify=False,
+                proxy_client_cert=proxy_client_cert,
+                proxies={ctx.REQUEST_PROTO: f'https://{server_address}'},
+            ) as rh:
+                proxy_info = ctx.proxy_info_request(rh)
+                assert proxy_info['proxy'] == server_address
+                assert proxy_info['connect'] is True
+                assert 'Proxy-Authorization' not in proxy_info['headers']
+
+    @pytest.mark.skipif(urllib3 is None, reason='requires urllib3 to test')
+    def test_https_connect_mtls_error(self, handler, ctx):
+        with ctx.http_server(MTLSHTTPSConnectProxyHandler) as server_address:
+            with handler(
+                proxy_verify=False,
+                verify=False,
+                proxy_client_cert=None,
+                proxies={ctx.REQUEST_PROTO: f'https://{server_address}'},
+            ) as rh:
+                with pytest.raises((ProxyError, SSLError)):
+                    ctx.proxy_info_request(rh)
+
+    @pytest.mark.skipif(urllib3 is None, reason='requires urllib3 to test')
+    @pytest.mark.skip_handler('CurlCFFI', 'legacy_ssl ignored by CurlCFFI')
+    def test_https_connect_legacy_ssl_support(self, handler, ctx):
+        with ctx.http_server(LegacyHTTPSConnectProxyHandler) as server_address:
+            with handler(proxy_verify=False, verify=False, proxy_legacy_ssl_support=True, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+                proxy_info = ctx.proxy_info_request(rh)
+                assert proxy_info['proxy'] == server_address
+                assert proxy_info['connect'] is True
+                assert 'Proxy-Authorization' not in proxy_info['headers']
+
+            with handler(proxy_verify=False, verify=False, proxy_legacy_ssl_support=False, proxies={ctx.REQUEST_PROTO: f'https://{server_address}'}) as rh:
+                with pytest.raises((ProxyError, SSLError)):
+                    ctx.proxy_info_request(rh)

test/test_networking.py

@@ -61,7 +61,7 @@ from yt_dlp.networking.impersonate import (
     ImpersonateRequestHandler,
     ImpersonateTarget,
 )
-from yt_dlp.utils import YoutubeDLError
+from yt_dlp.utils import YoutubeDLError, traverse_obj
 from yt_dlp.utils._utils import _YDLLogger as FakeLogger
 from yt_dlp.utils.networking import HTTPHeaderDict, std_headers
 
@@ -772,6 +772,10 @@ class TestClientCertificate:
             'client_certificate_password': 'foobar',
         })
 
+    def test_mtls_required(self, handler):
+        with pytest.raises(SSLError):
+            self._run_test(handler)
+
 
 @pytest.mark.parametrize('handler', ['CurlCFFI'], indirect=True)
 class TestHTTPImpersonateRequestHandler(TestRequestHandlerBase):
@@ -1776,6 +1780,7 @@ class TestYoutubeDLNetworking:
             'compat_opts': ['no-certifi'],
             'nocheckcertificate': True,
             'legacyserverconnect': True,
+            'proxy_nocheckcertificate': True,
         }) as ydl:
             rh = self.build_handler(ydl)
             assert rh.headers.get('test') == 'testtest'
@@ -1787,6 +1792,7 @@ class TestYoutubeDLNetworking:
             assert rh.prefer_system_certs is True
             assert rh.verify is False
             assert rh.legacy_ssl_support is True
+            assert rh.proxy_verify is False
 
     @pytest.mark.parametrize('ydl_params', [
         {'client_certificate': 'fakecert.crt'},
@@ -1799,6 +1805,22 @@ class TestYoutubeDLNetworking:
             rh = self.build_handler(ydl)
             assert rh._client_cert == ydl_params  # XXX: Too bound to implementation
 
+    @pytest.mark.parametrize('client_cert', [
+        {'client_certificate': 'fakecert.crt'},
+        {'client_certificate': 'fakecert.crt', 'client_certificate_key': 'fakekey.key'},
+        {'client_certificate': 'fakecert.crt', 'client_certificate_key': 'fakekey.key', 'client_certificate_password': 'foobar'},
+        {'client_certificate_key': 'fakekey.key', 'client_certificate_password': 'foobar'},
+    ])
+    def test_proxy_client_certificate(self, client_cert):
+        ydl_params = traverse_obj(client_cert, {
+            'proxy_client_certificate': 'client_certificate',
+            'proxy_client_certificate_key': 'client_certificate_key',
+            'proxy_client_certificate_password': 'client_certificate_password',
+        })
+        with FakeYDL(ydl_params) as ydl:
+            rh = self.build_handler(ydl)
+            assert rh._proxy_client_cert == client_cert
+
     def test_urllib_file_urls(self):
         with FakeYDL({'enable_file_urls': False}) as ydl:
             rh = self.build_handler(ydl, UrllibRH)

test/test_websockets.py

@@ -356,7 +356,7 @@ class TestWebsSocketRequestHandlerConformance:
             'client_certificate_key': os.path.join(MTLS_CERT_DIR, 'clientencrypted.key'),
             'client_certificate_password': 'foobar',
         },
-    ))
+    ), ids=['combined_nopass', 'nocombined_nopass', 'combined_pass', 'nocombined_pass'])
     def test_mtls(self, handler, client_cert):
         with handler(
             # Disable client-side validation of unacceptable self-signed testcert.pem
@@ -366,6 +366,15 @@ class TestWebsSocketRequestHandlerConformance:
         ) as rh:
             ws_validate_and_send(rh, Request(self.mtls_wss_base_url)).close()
 
+    def test_mtls_required(self, handler):
+        with handler(
+            # Disable client-side validation of unacceptable self-signed testcert.pem
+            # The test is of a check on the server side, so unaffected
+            verify=False,
+        ) as rh:
+            with pytest.raises(SSLError):
+                ws_validate_and_send(rh, Request(self.mtls_wss_base_url))
+
     def test_request_disable_proxy(self, handler):
         for proxy_proto in handler._SUPPORTED_PROXY_SCHEMES or ['ws']:
             # Given handler is configured with a proxy

yt_dlp/YoutubeDL.py

@@ -340,10 +340,15 @@ class YoutubeDL:
     legacyserverconnect: Explicitly allow HTTPS connection to servers that do not
                        support RFC 5746 secure renegotiation
     nocheckcertificate:  Do not verify SSL certificates
+    proxy_nocheckcertificate:  Do not verify SSL certificates for HTTPS proxy
     client_certificate:  Path to client certificate file in PEM format. May include the private key
     client_certificate_key:  Path to private key file for client certificate
     client_certificate_password:  Password for client certificate private key, if encrypted.
                         If not provided and the key is encrypted, yt-dlp will ask interactively
+    proxy_client_certificate:  Path to client certificate file in PEM format for HTTPS proxy. May include the private key
+    proxy_client_certificate_key:  Path to private key file for client certificate for HTTPS proxy.
+    proxy_client_certificate_password:  Password for client certificate private key, if encrypted, for HTTPS proxy.
+                        If not provided and the key is encrypted, yt-dlp will ask interactively
     prefer_insecure:   Use HTTP instead of HTTPS to retrieve information.
                        (Only supported by some extractors)
     enable_file_urls:  Enable file:// URLs. This is disabled by default for security reasons.
@@ -4221,6 +4226,7 @@ class YoutubeDL:
                 proxies=proxies,
                 prefer_system_certs='no-certifi' in self.params['compat_opts'],
                 verify=not self.params.get('nocheckcertificate'),
+                proxy_verify=not self.params.get('proxy_nocheckcertificate'),
                 **traverse_obj(self.params, {
                     'verbose': 'debug_printtraffic',
                     'source_address': 'source_address',
@@ -4233,6 +4239,11 @@ class YoutubeDL:
                         'client_certificate_key': 'client_certificate_key',
                         'client_certificate_password': 'client_certificate_password',
                     },
+                    'proxy_client_cert': {
+                        'client_certificate': 'proxy_client_certificate',
+                        'client_certificate_key': 'proxy_client_certificate_key',
+                        'client_certificate_password': 'proxy_client_certificate_password',
+                    },
                 }),
             ))
         director.preferences.update(preferences or [])

yt_dlp/__init__.py

@@ -790,6 +790,9 @@ def parse_options(argv=None):
         'client_certificate': opts.client_certificate,
         'client_certificate_key': opts.client_certificate_key,
         'client_certificate_password': opts.client_certificate_password,
+        'proxy_client_certificate': opts.proxy_client_certificate,
+        'proxy_client_certificate_key': opts.proxy_client_certificate_key,
+        'proxy_client_certificate_password': opts.proxy_client_certificate_password,
         'quiet': opts.quiet,
         'no_warnings': opts.no_warnings,
         'forceurl': opts.geturl,
@@ -902,6 +905,7 @@ def parse_options(argv=None):
         'cookiesfrombrowser': opts.cookiesfrombrowser,
         'legacyserverconnect': opts.legacy_server_connect,
         'nocheckcertificate': opts.no_check_certificate,
+        'proxy_nocheckcertificate': opts.proxy_no_check_certificate,
         'prefer_insecure': opts.prefer_insecure,
         'enable_file_urls': opts.enable_file_urls,
         'http_headers': opts.headers,

yt_dlp/networking/_curlcffi.py

@@ -187,7 +187,7 @@ class CurlCFFIRH(ImpersonateRequestHandler, InstanceStoreMixin):
             # curl_cffi does not currently set these for proxies
             session.curl.setopt(CurlOpt.PROXY_CAINFO, certifi.where())
 
-            if not self.verify:
+            if not self.proxy_verify:
                 session.curl.setopt(CurlOpt.PROXY_SSL_VERIFYPEER, 0)
                 session.curl.setopt(CurlOpt.PROXY_SSL_VERIFYHOST, 0)
 
@@ -202,6 +202,15 @@ class CurlCFFIRH(ImpersonateRequestHandler, InstanceStoreMixin):
             if client_certificate_password:
                 session.curl.setopt(CurlOpt.KEYPASSWD, client_certificate_password)
 
+        if self._proxy_client_cert:
+            session.curl.setopt(CurlOpt.PROXY_SSLCERT, self._proxy_client_cert['client_certificate'])
+            proxy_client_certificate_key = self._proxy_client_cert.get('client_certificate_key')
+            proxy_client_certificate_password = self._proxy_client_cert.get('client_certificate_password')
+            if proxy_client_certificate_key:
+                session.curl.setopt(CurlOpt.PROXY_SSLKEY, proxy_client_certificate_key)
+            if proxy_client_certificate_password:
+                session.curl.setopt(CurlOpt.PROXY_KEYPASSWD, proxy_client_certificate_password)
+
         timeout = self._calculate_timeout(request)
 
         # set CURLOPT_LOW_SPEED_LIMIT and CURLOPT_LOW_SPEED_TIME to act as a read timeout. [1]
@@ -243,6 +252,8 @@ class CurlCFFIRH(ImpersonateRequestHandler, InstanceStoreMixin):
                 or (e.code == CurlECode.RECV_ERROR and 'CONNECT' in str(e))
             ):
                 raise ProxyError(cause=e) from e
+            elif e.code == CurlECode.RECV_ERROR and 'SSL' in str(e):
+                raise SSLError(cause=e) from e
             else:
                 raise TransportError(cause=e) from e
 

yt_dlp/networking/_requests.py

@@ -301,6 +301,7 @@ class RequestsRH(RequestHandler, InstanceStoreMixin):
         session = RequestsSession()
         http_adapter = RequestsHTTPAdapter(
             ssl_context=self._make_sslcontext(legacy_ssl_support=legacy_ssl_support),
+            proxy_ssl_context=self._make_proxy_sslcontext(),
             source_address=self.source_address,
             max_retries=urllib3.util.retry.Retry(False),
         )

yt_dlp/networking/common.py

@@ -187,10 +187,14 @@ class RequestHandler(abc.ABC):
     @param source_address: Client-side IP address to bind to for requests.
     @param verbose: Print debug request and traffic information to stdout.
     @param prefer_system_certs: Whether to prefer system certificates over other means (e.g. certifi).
-    @param client_cert: SSL client certificate configuration.
+    @param client_cert: SSL client certificate configuration.z
             dict with {client_certificate, client_certificate_key, client_certificate_password}
+    @param proxy_client_cert: SSL client certificate configuration for proxy connections.
+        dict with {client_certificate, client_certificate_key, client_certificate_password}
     @param verify: Verify SSL certificates
+    @param proxy_verify: Verify SSL certificates of proxy connections
     @param legacy_ssl_support: Enable legacy SSL options such as legacy server connect and older cipher support.
+    @param proxy_legacy_ssl_support: Enable legacy SSL options such as legacy server connect and older cipher support for proxy connections.
 
     Some configuration options may be available for individual Requests too. In this case,
     either the Request configuration option takes precedence or they are merged.
@@ -230,8 +234,11 @@ class RequestHandler(abc.ABC):
         verbose: bool = False,
         prefer_system_certs: bool = False,
         client_cert: dict[str, str | None] | None = None,
+        proxy_client_cert: dict[str, str | None] | None = None,
         verify: bool = True,
+        proxy_verify: bool = True,
         legacy_ssl_support: bool = False,
+        proxy_legacy_ssl_support: bool = False,
         **_,
     ):
 
@@ -244,8 +251,11 @@ class RequestHandler(abc.ABC):
         self.verbose = verbose
         self.prefer_system_certs = prefer_system_certs
         self._client_cert = client_cert or {}
+        self._proxy_client_cert = proxy_client_cert or {}
         self.verify = verify
+        self.proxy_verify = proxy_verify
         self.legacy_ssl_support = legacy_ssl_support
+        self.proxy_legacy_ssl_support = proxy_legacy_ssl_support
         super().__init__()
 
     def _make_sslcontext(self, legacy_ssl_support=None):
@@ -256,6 +266,14 @@ class RequestHandler(abc.ABC):
             **self._client_cert,
         )
 
+    def _make_proxy_sslcontext(self, legacy_ssl_support=None):
+        return make_ssl_context(
+            verify=self.proxy_verify,
+            legacy_support=legacy_ssl_support if legacy_ssl_support is not None else self.proxy_legacy_ssl_support,
+            use_certifi=not self.prefer_system_certs,
+            **self._proxy_client_cert,
+        )
+
     def _merge_headers(self, request_headers):
         return HTTPHeaderDict(self.headers, request_headers)
 

yt_dlp/options.py

@@ -781,6 +781,20 @@ def create_parser():
         help='Password for client certificate private key, if encrypted. '
              'If not provided, and the key is encrypted, yt-dlp will ask interactively')
 
+    authentication.add_option(
+        '--proxy-client-certificate',
+        dest='proxy_client_certificate', metavar='CERTFILE',
+        help='Path to client certificate file in PEM format for HTTPS proxy. May include the private key')
+    authentication.add_option(
+        '--proxy-client-certificate-key',
+        dest='proxy_client_certificate_key', metavar='KEYFILE',
+        help='Path to private key file for client certificate for HTTPS proxy')
+    authentication.add_option(
+        '--proxy-client-certificate-password',
+        dest='proxy_client_certificate_password', metavar='PASSWORD',
+        help='Password for client certificate private key, if encrypted, for HTTPS proxy. '
+             'If not provided, and the key is encrypted, yt-dlp will ask interactively')
+
     video_format = optparse.OptionGroup(parser, 'Video Format Options')
     video_format.add_option(
         '-f', '--format',
@@ -1084,6 +1098,10 @@ def create_parser():
         '--no-check-certificates',
         action='store_true', dest='no_check_certificate', default=False,
         help='Suppress HTTPS certificate validation')
+    workarounds.add_option(
+        '--proxy-no-check-certificates',
+        action='store_true', dest='proxy_no_check_certificate', default=False,
+        help='Suppress HTTPS Proxy certificate validation')
     workarounds.add_option(
         '--prefer-insecure', '--prefer-unsecure',
         action='store_true', dest='prefer_insecure',