fix(assessment): establish independent release trust

tools/release/govoplan_release/http_fetch.py

@@ -8,6 +8,9 @@ from dataclasses import dataclass
 from typing import Mapping
 
 
+DEFAULT_MAX_RESPONSE_BYTES = 16 * 1024 * 1024
+
+
 @dataclass(frozen=True, slots=True)
 class HttpFetchResponse:
     status: int
@@ -34,11 +37,29 @@ def fetch_http(
     label: str = "URL",
     method: str = "GET",
     headers: Mapping[str, str] | None = None,
+    max_response_bytes: int = DEFAULT_MAX_RESPONSE_BYTES,
 ) -> HttpFetchResponse:
-    request = urllib.request.Request(validate_http_url(url, label=label), headers=dict(headers or {}), method=method)
+    if max_response_bytes <= 0:
+        raise ValueError("max_response_bytes must be positive.")
+    request = urllib.request.Request(
+        validate_http_url(url, label=label),
+        headers=dict(headers or {}),
+        method=method,
+    )
     with urllib.request.urlopen(request, timeout=timeout) as response:  # noqa: S310 - URL is validated by validate_http_url.  # nosec B310  # nosemgrep: python.lang.security.audit.dynamic-urllib-use-detected.dynamic-urllib-use-detected
+        raw_length = response.headers.get("Content-Length")
+        if raw_length is not None:
+            try:
+                declared_length = int(raw_length)
+            except (TypeError, ValueError):
+                declared_length = None
+            if declared_length is not None and declared_length > max_response_bytes:
+                raise ValueError(f"{label} response exceeds the configured size limit.")
+        body = response.read(max_response_bytes + 1)
+        if len(body) > max_response_bytes:
+            raise ValueError(f"{label} response exceeds the configured size limit.")
         return HttpFetchResponse(
             status=int(getattr(response, "status", 0)),
             headers=dict(response.headers.items()),
-            body=response.read(),
+            body=body,
         )