Validate :: name separator with identifier check

Only treat :: as a name::regex separator when the left-hand side
is a valid identifier (letters, digits, underscores, hyphens).
This prevents regex patterns containing :: (e.g. IPv6 ::ffff:\d+)
from being silently corrupted by splitting on ::.

Added tests for bare :: in regex and valid name:: prefix.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

litellm/proxy/guardrails/guardrail_endpoints.py

@@ -1016,6 +1016,12 @@ _NESTED_QUANTIFIER_RE = re.compile(
     r"\([^)]*[*+]\)[*+?]|\([^)]*[*+]\)\{",
 )
 
+# A valid pattern name must look like an identifier: letters, digits,
+# underscores, hyphens — no regex metacharacters.  Used to decide whether
+# a ``::`` in a line is a name separator or part of the regex itself
+# (e.g. IPv6 patterns like ``::ffff:\d+``).
+_VALID_PATTERN_NAME_RE = re.compile(r"^[A-Za-z_][A-Za-z0-9_-]*$")
+
 
 def _check_redos_heuristic(pattern: str) -> Optional[str]:
     """Return an error message if the pattern looks like it could cause ReDoS."""
@@ -1105,15 +1111,20 @@ async def validate_patterns_file(request: Dict[str, str]):
                     )
                     break
 
-                # Parse optional name::regex format (:: avoids conflict with
-                # regex alternation operator |)
+                # Parse optional name::regex format.  Only treat :: as a
+                # name separator when the left-hand side is a valid
+                # identifier; otherwise the whole line is the regex
+                # (e.g. ``::ffff:\d+`` for IPv6).
+                name: Optional[str] = None
+                regex_str = stripped
                 if "::" in stripped:
                     parts = stripped.split("::", 1)
-                    name = parts[0].strip()
-                    regex_str = parts[1].strip()
-                else:
-                    name = None
-                    regex_str = stripped
+                    candidate_name = parts[0].strip()
+                    if candidate_name and _VALID_PATTERN_NAME_RE.match(
+                        candidate_name
+                    ):
+                        name = candidate_name
+                        regex_str = parts[1].strip()
 
                 if not regex_str:
                     errors.append(f"Line {line_num}: empty regex pattern")

tests/test_litellm/proxy/guardrails/test_guardrail_endpoints.py

@@ -1203,6 +1203,26 @@ class TestValidatePatternsFile:
         assert result["valid"] is False
         assert "too large" in result.get("error", "").lower()
 
+    @pytest.mark.asyncio
+    async def test_validate_patterns_double_colon_in_regex(self):
+        """:: in regex (e.g. IPv6) should not be treated as name separator."""
+        file_content = "::ffff:\\d+"
+        result = await validate_patterns_file({"file_content": file_content})
+        assert result["valid"] is True
+        assert len(result["patterns"]) == 1
+        assert result["patterns"][0]["pattern"] == "::ffff:\\d+"
+        assert result["patterns"][0]["name"] == "pattern_line_1"
+
+    @pytest.mark.asyncio
+    async def test_validate_patterns_named_with_double_colon(self):
+        """Valid identifier before :: is treated as name, rest as regex."""
+        file_content = "ipv6_match::fe80::\\w+"
+        result = await validate_patterns_file({"file_content": file_content})
+        assert result["valid"] is True
+        assert len(result["patterns"]) == 1
+        assert result["patterns"][0]["name"] == "ipv6_match"
+        assert result["patterns"][0]["pattern"] == "fe80::\\w+"
+
     @pytest.mark.asyncio
     async def test_validate_patterns_only_comments(self):
         """File with only comments returns no patterns error."""