harden: bound HTTP reads and enforce strict redirects (#3140)

* harden: bound HTTP reads and enforce strict redirects

Add a shared _download_security module (read_response_limited,
is_https_or_localhost_http, size constants) and route the GitHub release
and Azure DevOps token network reads through bounded reads so an oversized
response can't exhaust memory.

Add a strict_redirects mode to authentication.open_url: the redirect handler
now rejects any redirect whose target isn't HTTPS (or HTTP to localhost),
composing with the existing per-hop redirect_validator and auth-stripping.
The Azure DevOps token POST is routed through that handler so a 307/308
cannot forward the client_secret body to a non-HTTPS host.

Assisted-by: Codex (model: GPT-5, autonomous)

* test: align HTTP fakes with bounded reads

Assisted-by: Codex (model: GPT-5, autonomous)

* fix: tolerate invalid token response encoding

Assisted-by: Codex (model: GPT-5, autonomous)

* test: align GHES fakes with bounded reads

Assisted-by: Codex (model: GPT-5, autonomous)

* test: reuse shared upgrade HTTP response helper

Assisted-by: Codex (model: GPT-5, autonomous)

* fix: include rejected redirect target in error

Assisted-by: Codex (model: GPT-5, autonomous)

* fix: enforce strict redirects by default

Assisted-by: Codex (model: GPT-5, autonomous)

* fix: close redirect credential and SSRF gaps

Assisted-by: Codex (model: GPT-5, autonomous)

tests/test_extensions.py

@@ -9,6 +9,7 @@ Tests cover:
 - Catalog stack (multi-catalog support)
 """
 
+import io
 import pytest
 import json
 import os
@@ -22,6 +23,7 @@ from datetime import datetime, timezone
 from unittest.mock import MagicMock
 
 from tests.conftest import strip_ansi
+from tests.http_helpers import route_opener_open_through_urlopen  # noqa: F401
 from specify_cli import extensions as _ext_module
 from specify_cli.extensions import (
     CatalogEntry,
@@ -4978,7 +4980,7 @@ class TestExtensionCatalog:
         zip_bytes = zip_buf.getvalue()
 
         release_response = MagicMock()
-        release_response.read.return_value = json.dumps(
+        release_response.read.side_effect = io.BytesIO(json.dumps(
             {
                 "assets": [
                     {
@@ -4987,12 +4989,12 @@ class TestExtensionCatalog:
                     }
                 ]
             }
-        ).encode()
+        ).encode()).read
         release_response.__enter__ = lambda s: s
         release_response.__exit__ = MagicMock(return_value=False)
 
         asset_response = MagicMock()
-        asset_response.read.return_value = zip_bytes
+        asset_response.read.side_effect = io.BytesIO(zip_bytes).read
         asset_response.__enter__ = lambda s: s
         asset_response.__exit__ = MagicMock(return_value=False)
 
@@ -8761,10 +8763,10 @@ def test_extension_wrapper_resolves_ghes_asset_when_host_configured(tmp_path, mo
     def fake_open(url, timeout=None, extra_headers=None):
         captured.append(url)
         resp = MagicMock()
-        resp.read.return_value = json.dumps({
+        resp.read.side_effect = io.BytesIO(json.dumps({
             "assets": [{"name": "ext.zip",
                         "url": "https://ghes.example/api/v3/repos/o/r/releases/assets/7"}]
-        }).encode()
+        }).encode()).read
         yield resp
 
     monkeypatch.setattr(catalog, "_open_url", fake_open)