fix(python): send an IPv6 WebRTC address to setWebRTCIPv6

The per-context init script passed every webrtc_ip, IPv6 included, to
window.setWebRTCIPv4(), and never called setWebRTCIPv6(). An IPv6 address
(given directly, or resolved as a proxy's exit IP) was stored as the
context's IPv4 value and the IPv6 slot stayed empty. The script now picks
the setter by address family, and an address that is neither raises
InvalidIP instead of being passed through.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

pythonlib/camoufox/async_api.py

@@ -204,7 +204,7 @@ async def AsyncNewContext(
         preset: A fingerprint preset dict to use. If None, fpgen draws a new identity.
         os: Target OS for the drawn identity ("windows", "macos", "linux").
         ff_version: Firefox major version to claim in the UA. Defaults to the browser's own.
-        webrtc_ip: IPv4 address to spoof for WebRTC ICE candidates.
+        webrtc_ip: IPv4 or IPv6 address to spoof for WebRTC ICE candidates.
         proxy: Per-context proxy (Playwright format: {"server": "...", "username": "...", "password": "..."}).
             Unless webrtc_ip and timezone_id are both given, they are looked up from the
             proxy's exit IP; InvalidIP is raised if that lookup fails.

pythonlib/camoufox/fingerprints.py

@@ -11,6 +11,7 @@ from random import Random, choice, randint, randrange
 from typing import Any, Dict, FrozenSet, List, Optional, Set, Tuple
 
 from camoufox._warnings import FallbackWarning
+from camoufox.ip import valid_ipv4, validate_ip
 from camoufox.pkgman import load_yaml
 from camoufox.webgl import sample_webgl
 
@@ -1759,8 +1760,10 @@ def _build_init_script(values: Dict[str, Any]) -> str:
     # WebRTC IP
     ip = values.get('webrtcIP')
     if ip:
+        validate_ip(ip)
+        fn_name = 'setWebRTCIPv4' if valid_ipv4(ip) else 'setWebRTCIPv6'
         lines.append(
-            f'  if (typeof w.setWebRTCIPv4 === "function") w.setWebRTCIPv4({_json.dumps(ip)});'
+            f'  if (typeof w.{fn_name} === "function") w.{fn_name}({_json.dumps(ip)});'
         )
     else:
         lines.append(

pythonlib/camoufox/sync_api.py

@@ -182,7 +182,7 @@ def NewContext(
         preset: A fingerprint preset dict to use. If None, fpgen draws a new identity.
         os: Target OS for the drawn identity ("windows", "macos", "linux").
         ff_version: Firefox major version to claim in the UA. Defaults to the browser's own.
-        webrtc_ip: IPv4 address to spoof for WebRTC ICE candidates.
+        webrtc_ip: IPv4 or IPv6 address to spoof for WebRTC ICE candidates.
         proxy: Per-context proxy (Playwright format: {"server": "...", "username": "...", "password": "..."}).
             Unless webrtc_ip and timezone_id are both given, they are looked up from the
             proxy's exit IP; InvalidIP is raised if that lookup fails.

pythonlib/tests/test_webrtc_ip_setter.py

@@ -0,0 +1,23 @@
+"""The per-context init script hands a WebRTC IP to the setter for its family."""
+
+import pytest
+
+from camoufox.exceptions import InvalidIP
+from camoufox.fingerprints import _build_init_script
+
+
+def test_ipv4_goes_to_the_ipv4_setter():
+    script = _build_init_script({"webrtcIP": "203.0.113.7"})
+    assert 'w.setWebRTCIPv4("203.0.113.7")' in script
+    assert "setWebRTCIPv6(" not in script
+
+
+def test_ipv6_goes_to_the_ipv6_setter():
+    script = _build_init_script({"webrtcIP": "2001:db8::7"})
+    assert 'w.setWebRTCIPv6("2001:db8::7")' in script
+    assert "2001:db8::7" not in script.split("setWebRTCIPv6")[0]
+
+
+def test_an_invalid_address_is_refused():
+    with pytest.raises(InvalidIP):
+        _build_init_script({"webrtcIP": "not-an-ip"})