Fenrir fixes (2026-06-23)

certs/crl.pem

@@ -1,41 +1,42 @@
 Certificate Revocation List (CRL):
         Version 2 (0x1)
         Signature Algorithm: sha256WithRSAEncryption
-        Issuer: C = US, ST = Montana, L = Bozeman, O = Sawtooth, OU = Consulting, CN = www.wolfssl.com, emailAddress = info@wolfssl.com
-        Last Update: Feb 15 12:50:27 2022 GMT
-        Next Update: Nov 11 12:50:27 2024 GMT
+        Issuer: C=US, ST=Montana, L=Bozeman, O=Sawtooth, OU=Consulting, CN=www.wolfssl.com, emailAddress=info@wolfssl.com
+        Last Update: Nov 13 20:41:50 2025 GMT
+        Next Update: Aug  9 20:41:50 2028 GMT
         CRL extensions:
             X509v3 CRL Number: 
                 2
 Revoked Certificates:
     Serial Number: 02
-        Revocation Date: Feb 15 12:50:27 2022 GMT
+        Revocation Date: Nov 13 20:41:50 2025 GMT
     Signature Algorithm: sha256WithRSAEncryption
-         43:e6:3b:30:0e:32:53:32:a4:08:3c:e5:d5:2e:f1:ce:e9:95:
-         ff:ba:d6:fe:2e:59:80:f8:0a:2f:cf:1e:e0:37:fe:ca:cc:33:
-         66:8b:ed:65:50:7d:44:92:d3:5c:52:9a:95:a5:9d:a5:4e:77:
-         8b:b4:7f:59:c8:7a:e0:eb:34:32:ae:a1:03:99:d2:3c:c0:f4:
-         7e:1c:87:4c:6c:5a:ba:0a:95:e8:a1:44:01:7b:8f:3e:a4:e3:
-         e8:1e:07:19:f0:09:7a:85:8f:f3:82:62:f8:1e:08:51:a3:60:
-         30:5b:06:c8:a2:b3:ff:aa:28:66:ad:fe:4b:81:49:30:ef:5f:
-         5d:ac:d9:ad:17:9f:2a:b6:22:d6:35:cc:9f:d9:11:26:dd:7a:
-         06:35:d0:d5:c7:41:6c:52:97:8c:aa:82:5a:e5:a8:58:d4:b7:
-         2b:31:84:34:15:bd:08:e4:9e:71:9e:c5:40:f8:02:a3:a0:1e:
-         4f:98:72:2b:eb:9e:8a:4e:01:83:88:e5:cb:6e:3b:52:e3:a9:
-         34:a1:7c:e4:79:2c:d1:e0:0b:74:22:ba:6d:cb:c3:a1:56:f9:
-         c9:f4:20:bf:00:49:df:6b:59:49:18:c7:75:27:8e:a1:5a:a6:
-         ff:f2:be:34:4a:c9:6d:6e:24:a3:1f:15:7e:34:90:b6:81:bf:
-         15:80:c3:ac
+    Signature Value:
+        b7:0d:1c:78:99:1c:e8:0b:d9:33:a2:95:01:ad:cf:35:e9:86:
+        28:7f:49:6b:93:76:c1:70:08:61:aa:77:57:34:af:45:82:78:
+        5d:3b:7b:67:ca:b4:fb:d1:68:13:be:34:94:84:2d:65:ad:97:
+        52:69:1d:67:ea:8e:a7:ff:21:0f:21:6c:8c:75:7f:c7:50:c5:
+        6b:a5:fd:cd:3f:91:64:7b:5e:0f:4a:9c:c8:cd:39:a0:30:ad:
+        80:27:50:e0:a7:bf:19:68:cf:6b:26:75:51:14:77:5a:62:6d:
+        bc:66:1a:90:f7:00:09:34:c7:d0:9d:81:f3:b5:9f:90:40:02:
+        8d:3f:68:7f:0d:1d:c5:00:32:e5:cf:42:35:1c:b6:eb:02:a8:
+        d7:2a:a7:f3:f1:10:e2:d5:9e:41:de:2f:78:7d:7f:ad:68:06:
+        a0:6d:40:96:dd:35:59:4d:a0:d3:bd:2e:ba:b6:75:f8:1c:43:
+        b9:c0:b7:75:c4:38:59:46:00:71:ab:5a:df:f5:62:e9:ac:2b:
+        76:11:4f:1b:42:2c:dd:b2:38:6e:57:cf:c5:75:67:4c:3e:27:
+        bb:4c:d5:09:2c:4a:13:3d:8b:9c:89:76:b7:bd:73:1b:64:50:
+        ea:d5:13:0e:51:48:d8:43:08:93:00:85:8f:2f:08:ad:0d:aa:
+        d6:6c:f8:3d
 -----BEGIN X509 CRL-----
 MIICBDCB7QIBATANBgkqhkiG9w0BAQsFADCBlDELMAkGA1UEBhMCVVMxEDAOBgNV
 BAgMB01vbnRhbmExEDAOBgNVBAcMB0JvemVtYW4xETAPBgNVBAoMCFNhd3Rvb3Ro
 MRMwEQYDVQQLDApDb25zdWx0aW5nMRgwFgYDVQQDDA93d3cud29sZnNzbC5jb20x
-HzAdBgkqhkiG9w0BCQEWEGluZm9Ad29sZnNzbC5jb20XDTIyMDIxNTEyNTAyN1oX
-DTI0MTExMTEyNTAyN1owFDASAgECFw0yMjAyMTUxMjUwMjdaoA4wDDAKBgNVHRQE
-AwIBAjANBgkqhkiG9w0BAQsFAAOCAQEAQ+Y7MA4yUzKkCDzl1S7xzumV/7rW/i5Z
-gPgKL88e4Df+yswzZovtZVB9RJLTXFKalaWdpU53i7R/Wch64Os0Mq6hA5nSPMD0
-fhyHTGxaugqV6KFEAXuPPqTj6B4HGfAJeoWP84Ji+B4IUaNgMFsGyKKz/6ooZq3+
-S4FJMO9fXazZrRefKrYi1jXMn9kRJt16BjXQ1cdBbFKXjKqCWuWoWNS3KzGENBW9
-COSecZ7FQPgCo6AeT5hyK+ueik4Bg4jly247UuOpNKF85Hks0eALdCK6bcvDoVb5
-yfQgvwBJ32tZSRjHdSeOoVqm//K+NErJbW4kox8VfjSQtoG/FYDDrA==
+HzAdBgkqhkiG9w0BCQEWEGluZm9Ad29sZnNzbC5jb20XDTI1MTExMzIwNDE1MFoX
+DTI4MDgwOTIwNDE1MFowFDASAgECFw0yNTExMTMyMDQxNTBaoA4wDDAKBgNVHRQE
+AwIBAjANBgkqhkiG9w0BAQsFAAOCAQEAtw0ceJkc6AvZM6KVAa3PNemGKH9Ja5N2
+wXAIYap3VzSvRYJ4XTt7Z8q0+9FoE740lIQtZa2XUmkdZ+qOp/8hDyFsjHV/x1DF
+a6X9zT+RZHteD0qcyM05oDCtgCdQ4Ke/GWjPayZ1URR3WmJtvGYakPcACTTH0J2B
+87WfkEACjT9ofw0dxQAy5c9CNRy26wKo1yqn8/EQ4tWeQd4veH1/rWgGoG1Alt01
+WU2g070uurZ1+BxDucC3dcQ4WUYAcata3/Vi6awrdhFPG0Is3bI4blfPxXVnTD4n
+u0zVCSxKEz2LnIl2t71zG2RQ6tUTDlFI2EMIkwCFjy8IrQ2q1mz4PQ==
 -----END X509 CRL-----

examples/client.py

@@ -89,6 +89,12 @@ def build_arg_parser():
         help="Disable client cert check"
     )
 
+    parser.add_argument(
+        "-n", action="store_true",
+        help="Disable server hostname check "
+             "(IP literal hosts are never hostname-checked)"
+    )
+
     parser.add_argument(
         "-g", action="store_true",
         help="Send server HTTP GET"
@@ -125,6 +131,54 @@ def get_DTLSmethod(index):
         wolfssl.PROTOCOL_DTLSv1_3
     )[index]
 
+def is_ip_literal(host):
+    # AI_NUMERICHOST never resolves, it only parses. Unlike
+    # socket.inet_pton() it is available on every supported platform.
+    try:
+        socket.getaddrinfo(host, None, 0, 0, 0, socket.AI_NUMERICHOST)
+        return True
+    except socket.error:
+        return False
+
+
+def configure_verification(context, args):
+    """
+    Configure peer certificate and hostname verification on the context
+    according to the parsed arguments. Returns the server_hostname to pass
+    to wrap_socket() (None when no hostname check should be performed).
+
+    When certificate verification is enabled (the default), hostname
+    verification is enabled too so that a CA-trusted certificate issued for
+    a different host is rejected. Pass -n to opt out explicitly (e.g. when
+    using test certificates).
+
+    IP literal hosts are not hostname-checked: wolfSSL_check_domain_name()
+    only matches DNS names (iPAddress SANs are skipped on this path), and
+    RFC 6066 forbids IP literals in SNI. Certificate verification against
+    the CA still applies. Connect by DNS name to also verify the hostname.
+    """
+    if args.d:
+        context.verify_mode = wolfssl.CERT_NONE
+        context.check_hostname = False
+        return None
+
+    context.verify_mode = wolfssl.CERT_REQUIRED
+    context.load_verify_locations(args.A)
+
+    if args.n:
+        context.check_hostname = False
+        return None
+
+    if is_ip_literal(args.h):
+        print("Note: skipping hostname check for IP literal '{}'. "
+              "Connect by DNS name to enable it.".format(args.h))
+        context.check_hostname = False
+        return None
+
+    context.check_hostname = True
+    return args.h
+
+
 def main():
     args = build_arg_parser().parse_args()
 
@@ -147,18 +201,15 @@ def main():
 
     context.load_cert_chain(args.c, args.k)
 
-    if args.d:
-        context.verify_mode = wolfssl.CERT_NONE
-    else:
-        context.verify_mode = wolfssl.CERT_REQUIRED
-        context.load_verify_locations(args.A)
+    server_hostname = configure_verification(context, args)
 
     if args.l:
         context.set_ciphers(args.l)
 
     secure_socket = None
     try:
-        secure_socket = context.wrap_socket(bind_socket)
+        secure_socket = context.wrap_socket(
+            bind_socket, server_hostname=server_hostname)
 
         if not args.C:
             secure_socket.enable_crl(1)

examples/server.py

@@ -115,6 +115,21 @@ def get_DTLSmethod(index):
     )[index]
 
 
+# Large enough to peek a DTLS ClientHello source address.
+PEEK_BUFSIZE = 1500
+
+
+def peek_peer_address(sock):
+    """
+    Return the source address of the next pending datagram without removing
+    it from the socket queue. MSG_PEEK leaves the datagram (the DTLS
+    ClientHello) intact so wolfSSL_accept() can consume it during the
+    handshake.
+    """
+    _, from_addr = sock.recvfrom(PEEK_BUFSIZE, socket.MSG_PEEK)
+    return from_addr
+
+
 def main():
     args = build_arg_parser().parse_args()
     # DTLS connection over UDP
@@ -124,7 +139,6 @@ def main():
             args.v = 1
         bind_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
         bind_socket.bind(("" if args.b else "localhost", args.p))
-        data, from_addr = bind_socket.recvfrom(1)
         context = wolfssl.SSLContext(get_DTLSmethod(args.v), server_side=True)
     # SSL/TLS connection over TCP
     else:
@@ -156,6 +170,9 @@ def main():
         try:
             secure_socket = None
             if args.u:
+                # Peek the client's address for this connection without
+                # consuming the ClientHello datagram needed by the handshake.
+                from_addr = peek_peer_address(bind_socket)
                 secure_socket = context.wrap_socket(bind_socket)
             else:
                 new_socket, from_addr = bind_socket.accept()

tests/test_client_example.py

@@ -0,0 +1,171 @@
+# -*- coding: utf-8 -*-
+#
+# test_client_example.py
+#
+# Copyright (C) 2006-2020 wolfSSL Inc.
+#
+# This file is part of wolfSSL. (formerly known as CyaSSL)
+#
+# wolfSSL is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# wolfSSL is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+
+# pylint: disable=missing-docstring, invalid-name, import-error
+
+import os
+import socket
+import subprocess
+import sys
+import threading
+
+import wolfssl
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "examples"))
+import client as client_example  # noqa: E402
+
+
+def _args(argv):
+    return client_example.build_arg_parser().parse_args(argv)
+
+
+def _ctx():
+    return wolfssl.SSLContext(wolfssl.PROTOCOL_TLSv1_2)
+
+
+def test_verification_enables_hostname_check_by_default():
+    """
+    F-5621: with cert verification on (the default), the client must also
+    verify the peer's hostname and pass server_hostname to wrap_socket.
+    """
+    args = _args(["-h", "example.com"])
+    ctx = _ctx()
+
+    server_hostname = client_example.configure_verification(ctx, args)
+
+    assert ctx.verify_mode == wolfssl.CERT_REQUIRED
+    assert ctx.check_hostname is True
+    assert server_hostname == "example.com"
+
+
+def test_disable_cert_check_skips_hostname():
+    args = _args(["-d"])
+    ctx = _ctx()
+    # Simulate a reused context that previously had hostname checking on:
+    # -d must clear it, not leave it dangling against CERT_NONE.
+    ctx.verify_mode = wolfssl.CERT_REQUIRED
+    ctx.check_hostname = True
+
+    server_hostname = client_example.configure_verification(ctx, args)
+
+    assert ctx.verify_mode == wolfssl.CERT_NONE
+    assert ctx.check_hostname is False
+    assert server_hostname is None
+
+
+def test_hostname_check_can_be_opted_out():
+    """An explicit opt-out is provided for test certificates."""
+    args = _args(["-n"])
+    ctx = _ctx()
+    # Reused context with hostname checking previously enabled: -n must
+    # actively turn it back off.
+    ctx.verify_mode = wolfssl.CERT_REQUIRED
+    ctx.check_hostname = True
+
+    server_hostname = client_example.configure_verification(ctx, args)
+
+    assert ctx.verify_mode == wolfssl.CERT_REQUIRED
+    assert ctx.check_hostname is False
+    assert server_hostname is None
+
+
+def test_ip_literal_host_skips_hostname_check():
+    """
+    The default host (127.0.0.1) is an IP literal. wolfSSL's
+    check_domain_name() never matches iPAddress SANs, so the example must
+    not hostname-check IP literals; certificate verification stays on.
+    """
+    args = _args([])
+    ctx = _ctx()
+    ctx.verify_mode = wolfssl.CERT_REQUIRED
+    ctx.check_hostname = True
+
+    server_hostname = client_example.configure_verification(ctx, args)
+
+    assert args.h == "127.0.0.1"
+    assert ctx.verify_mode == wolfssl.CERT_REQUIRED
+    assert ctx.check_hostname is False
+    assert server_hostname is None
+
+
+def test_ipv6_literal_host_skips_hostname_check():
+    args = _args(["-h", "::1"])
+    ctx = _ctx()
+
+    server_hostname = client_example.configure_verification(ctx, args)
+
+    assert ctx.verify_mode == wolfssl.CERT_REQUIRED
+    assert ctx.check_hostname is False
+    assert server_hostname is None
+
+
+def _free_port():
+    sock = socket.socket()
+    sock.bind(("localhost", 0))
+    port = sock.getsockname()[1]
+    sock.close()
+    return port
+
+
+def test_default_invocation_end_to_end():
+    """
+    `python client.py` with the default host must complete a connection to
+    `python server.py` using the bundled certificates: verification is on
+    by default and the IP literal host must not trip the hostname check.
+    """
+    root = os.path.abspath(os.path.join(os.path.dirname(__file__), ".."))
+    port = _free_port()
+
+    # The examples must import the same wolfssl as this test process, even
+    # when the package is not installed (source-tree runs).
+    env = dict(os.environ)
+    pkg_root = os.path.dirname(os.path.dirname(os.path.abspath(
+        wolfssl.__file__)))
+    env["PYTHONPATH"] = os.pathsep.join(
+        [pkg_root] + ([env["PYTHONPATH"]] if env.get("PYTHONPATH") else []))
+
+    server = subprocess.Popen(
+        [sys.executable, "-u", os.path.join("examples", "server.py"),
+         "-p", str(port)],
+        cwd=root, env=env, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+    try:
+        line = server.stdout.readline().decode()
+        assert "Server listening" in line, line
+
+        client = subprocess.Popen(
+            [sys.executable, "-u", os.path.join("examples", "client.py"),
+             "-p", str(port)],
+            cwd=root, env=env, stdout=subprocess.PIPE,
+            stderr=subprocess.STDOUT)
+        # Watchdog instead of communicate(timeout=...), which is 3.3+.
+        watchdog = threading.Timer(60, client.kill)
+        watchdog.start()
+        try:
+            out, _ = client.communicate()
+        finally:
+            watchdog.cancel()
+
+        assert client.returncode == 0, out.decode()
+        assert b"I hear you fa shizzle" in out
+    finally:
+        server.kill()
+        server.wait()