feat: add bearer token auth check for MCP server

tests/test_havoc_mcp_server.py

@@ -38,3 +38,18 @@ def test_client_raises_on_error_response():
     client = DebugAgentClient(host="127.0.0.1", port=stub.port)
     with pytest.raises(DebugAgentError, match="DR0-DR3"):
         client.call("set_watchpoint", {"addr": "0x5000", "size": 4, "mode": "write"})
+
+
+from tools.havoc_mcp_server import check_bearer_token
+
+def test_check_bearer_token_accepts_matching_token():
+    assert check_bearer_token("Bearer secret123", expected="secret123") is True
+
+def test_check_bearer_token_rejects_wrong_token():
+    assert check_bearer_token("Bearer wrong", expected="secret123") is False
+
+def test_check_bearer_token_rejects_missing_header():
+    assert check_bearer_token(None, expected="secret123") is False
+
+def test_check_bearer_token_rejects_malformed_header():
+    assert check_bearer_token("secret123", expected="secret123") is False  # missing "Bearer " prefix

tools/havoc_mcp_server.py

@@ -34,3 +34,12 @@ class DebugAgentClient:
         if not response.get("ok"):
             raise DebugAgentError(response.get("error", "unknown debug agent error"))
         return response.get("result", {})
+
+
+def check_bearer_token(header_value: str | None, expected: str) -> bool:
+    if header_value is None:
+        return False
+    prefix = "Bearer "
+    if not header_value.startswith(prefix):
+        return False
+    return header_value[len(prefix):] == expected