fix(relay): secure reconnect and room ownership

scripts/ci_checks.sh

@@ -90,6 +90,7 @@ if python3 scripts/check_build_workflow.py &&
    python3 scripts/check_workflow_action_pins.py &&
    python3 scripts/test_check_workflow_action_pins.py &&
    python3 scripts/test_check_codegen.py &&
+   python3 scripts/test_generate_relay_protocol.py &&
    python3 scripts/test_format_native.py &&
    python3 scripts/check_update_packages_workflow.py &&
    python3 scripts/test_pubspec_version.py &&

scripts/generate_relay_protocol.py

@@ -11,17 +11,41 @@ SPEC_PATH = ROOT / "relay_protocol.json"
 DART_PATH = ROOT / "lib/watch_together/services/relay_protocol.g.dart"
 GO_PATH = ROOT / "server/relay_protocol_gen.go"
 
+SUPPORTED_ID_PATTERN = r"^[A-Za-z0-9_-]+$"
+
 
 def camel_to_pascal(value: str) -> str:
     return value[:1].upper() + value[1:]
 
 
+def validated_id_pattern(spec: dict) -> str:
+    try:
+        pattern = spec["idPattern"]
+    except KeyError:
+        raise ValueError("idPattern is required") from None
+    if not isinstance(pattern, str):
+        raise ValueError("idPattern must be a string")
+    if pattern != SUPPORTED_ID_PATTERN:
+        raise ValueError(
+            f"unsupported idPattern {pattern!r}; expected {SUPPORTED_ID_PATTERN!r}"
+        )
+    return pattern
+
+
 def dart_source(spec: dict) -> str:
+    id_pattern = validated_id_pattern(spec)
     lines = [
         "// Generated by scripts/generate_relay_protocol.py. Do not edit.",
         "",
         "abstract final class RelayProtocol {",
     ]
+    lines.extend(
+        [
+            f"  static const int protocolVersion = {spec['protocolVersion']};",
+            f"  static const int legacyProtocolVersion = {spec['legacyProtocolVersion']};",
+            "",
+        ]
+    )
     for group in ("clientMessageTypes", "serverMessageTypes"):
         for name, value in spec[group].items():
             lines.append(f"  static const String {name} = {value!r};")
@@ -33,7 +57,7 @@ def dart_source(spec: dict) -> str:
     lines.extend(
         [
             "",
-            "  static final RegExp _idPattern = RegExp(r'^[A-Za-z0-9_-]+$');",
+            f"  static final RegExp _idPattern = RegExp(r{id_pattern!r});",
             "",
             "  static bool isValidSessionId(String value) =>",
             "      value.isNotEmpty && value.length <= maxSessionIdLength && _idPattern.hasMatch(value);",
@@ -48,6 +72,7 @@ def dart_source(spec: dict) -> str:
 
 
 def go_source(spec: dict) -> str:
+    validated_id_pattern(spec)
     lines = [
         "// Code generated by scripts/generate_relay_protocol.py. DO NOT EDIT.",
         "",
@@ -55,6 +80,13 @@ def go_source(spec: dict) -> str:
         "",
         "const (",
     ]
+    lines.extend(
+        [
+            f"\trelayProtocolVersion       = {spec['protocolVersion']}",
+            f"\tlegacyRelayProtocolVersion = {spec['legacyProtocolVersion']}",
+            "",
+        ]
+    )
     protocol_constants = []
     for group in ("clientMessageTypes", "serverMessageTypes"):
         protocol_constants.extend(
@@ -109,8 +141,10 @@ def go_source(spec: dict) -> str:
 
 def main() -> None:
     spec = json.loads(SPEC_PATH.read_text(encoding="utf-8"))
-    DART_PATH.write_text(dart_source(spec), encoding="utf-8")
-    GO_PATH.write_text(go_source(spec), encoding="utf-8")
+    dart_output = dart_source(spec)
+    go_output = go_source(spec)
+    DART_PATH.write_text(dart_output, encoding="utf-8")
+    GO_PATH.write_text(go_output, encoding="utf-8")
 
 
 if __name__ == "__main__":

scripts/test_generate_relay_protocol.py

@@ -0,0 +1,72 @@
+import copy
+import json
+import tempfile
+import unittest
+from pathlib import Path
+from unittest import mock
+
+import generate_relay_protocol as generator
+
+
+class RelayProtocolGeneratorTest(unittest.TestCase):
+    def setUp(self) -> None:
+        self.spec = json.loads(generator.SPEC_PATH.read_text(encoding="utf-8"))
+
+    def test_supported_pattern_renders_both_targets(self) -> None:
+        dart_output = generator.dart_source(copy.deepcopy(self.spec))
+        go_output = generator.go_source(copy.deepcopy(self.spec))
+
+        self.assertIn(
+            f"RegExp(r{generator.SUPPORTED_ID_PATTERN!r})",
+            dart_output,
+        )
+        self.assertIn("func validRelayID(value string, maxLength int) bool", go_output)
+
+    def test_changed_pattern_fails_before_writing_either_target(self) -> None:
+        changed_spec = copy.deepcopy(self.spec)
+        changed_spec["idPattern"] = r"^[A-Za-z0-9_.-]+$"
+
+        for renderer in (generator.dart_source, generator.go_source):
+            with self.subTest(renderer=renderer.__name__):
+                with self.assertRaisesRegex(ValueError, "idPattern"):
+                    renderer(changed_spec)
+
+        with tempfile.TemporaryDirectory() as temporary_directory:
+            root = Path(temporary_directory)
+            spec_path = root / "relay_protocol.json"
+            dart_path = root / "relay_protocol.g.dart"
+            go_path = root / "relay_protocol_gen.go"
+            spec_path.write_text(json.dumps(changed_spec), encoding="utf-8")
+            dart_path.write_text("dart sentinel\n", encoding="utf-8")
+            go_path.write_text("go sentinel\n", encoding="utf-8")
+
+            with (
+                mock.patch.object(generator, "SPEC_PATH", spec_path),
+                mock.patch.object(generator, "DART_PATH", dart_path),
+                mock.patch.object(generator, "GO_PATH", go_path),
+            ):
+                with self.assertRaisesRegex(ValueError, "idPattern"):
+                    generator.main()
+
+            self.assertEqual(dart_path.read_text(encoding="utf-8"), "dart sentinel\n")
+            self.assertEqual(go_path.read_text(encoding="utf-8"), "go sentinel\n")
+
+    def test_missing_pattern_is_rejected(self) -> None:
+        spec = copy.deepcopy(self.spec)
+        del spec["idPattern"]
+
+        with self.assertRaisesRegex(ValueError, "idPattern is required"):
+            generator.validated_id_pattern(spec)
+
+    def test_non_string_pattern_is_rejected(self) -> None:
+        for value in (None, 42, [generator.SUPPORTED_ID_PATTERN]):
+            with self.subTest(value=value):
+                spec = copy.deepcopy(self.spec)
+                spec["idPattern"] = value
+
+                with self.assertRaisesRegex(ValueError, "idPattern must be a string"):
+                    generator.validated_id_pattern(spec)
+
+
+if __name__ == "__main__":
+    unittest.main()