Handle large proxy status responses

proxy_monitor_tui.py

@@ -22,6 +22,7 @@ DEFAULT_TIMEOUT_SECONDS = 10
 DEFAULT_TEST_URL = "https://www.gstatic.com/generate_204"
 DEFAULT_TEST_TIMEOUT_MS = 5000
 DEFAULT_DELAY_CONCURRENCY = 4
+MAX_JSON_RESPONSE_BYTES = 8 * 1024 * 1024
 
 
 class ApiError(RuntimeError):
@@ -154,7 +155,13 @@ class ProxyMonitorClient:
         )
         try:
             with urllib.request.urlopen(request, timeout=self.timeout_seconds) as response:
-                raw = response.read(1_048_576)
+                try:
+                    content_length = int(response.headers.get("Content-Length", "0"))
+                except ValueError:
+                    content_length = 0
+                if content_length > MAX_JSON_RESPONSE_BYTES:
+                    raise ApiError("response exceeds 8 MiB limit")
+                raw = response.read(MAX_JSON_RESPONSE_BYTES + 1)
         except urllib.error.HTTPError as exc:
             try:
                 detail = exc.read(1024).decode("utf-8", errors="replace").strip()
@@ -169,6 +176,8 @@ class ProxyMonitorClient:
 
         if not expect_json:
             return None
+        if len(raw) > MAX_JSON_RESPONSE_BYTES:
+            raise ApiError("response exceeds 8 MiB limit")
         if not raw:
             raise ApiError("response did not contain JSON")
         try: