Retry transient iOS bundle package downloads

frame/kdeconnect/fetch.py

@@ -7,8 +7,11 @@ ios/scripts/make_frame_bundle.py runs this; app/build/fetch-deps.js does the sam
 in Node. Usage: python3 frame/kdeconnect/fetch.py
 """
 import hashlib
+import http.client
 import json
 import sys
+import time
+import urllib.error
 import urllib.request
 from pathlib import Path
 
@@ -24,6 +27,25 @@ def sha256(data):
     return hashlib.sha256(data).hexdigest()
 
 
+def download_verified(url, expected_sha256):
+    for attempt in range(3):
+        try:
+            with urllib.request.urlopen(url, timeout=120) as response:
+                data = response.read()
+        except (OSError, http.client.HTTPException) as error:
+            # GitHub release downloads occasionally close during connection or
+            # transfer. Retry those failures, but fail fast on permanent HTTP errors.
+            if isinstance(error, urllib.error.HTTPError) and error.code not in (408, 429) and error.code < 500:
+                raise
+            if attempt == 2:
+                raise
+            time.sleep(attempt + 1)
+            continue
+        if sha256(data) != expected_sha256:
+            raise SystemExit(f"checksum mismatch for {url}: {sha256(data)}")
+        return data
+
+
 def fetch():
     m = manifest()
     PACKAGES.mkdir(exist_ok=True)
@@ -32,10 +54,7 @@ def fetch():
         if path.is_file() and sha256(path.read_bytes()) == p["sha256"]:
             continue
         url = m["release"] + p["file"]
-        with urllib.request.urlopen(url, timeout=120) as r:
-            data = r.read()
-        if sha256(data) != p["sha256"]:
-            raise SystemExit(f"checksum mismatch for {url}: {sha256(data)}")
+        data = download_verified(url, p["sha256"])
         tmp = path.with_suffix(".part")
         tmp.write_bytes(data)
         tmp.replace(path)

tests/test_kdeconnect_fetch.py

@@ -0,0 +1,53 @@
+"""The iOS Frame bundle must recover transient pinned package downloads."""
+import hashlib
+import http.client
+import importlib.util
+from pathlib import Path
+import unittest
+from unittest.mock import patch
+import urllib.error
+import io
+
+
+ROOT = Path(__file__).resolve().parent.parent
+SPEC = importlib.util.spec_from_file_location('kdeconnect_fetch', ROOT / 'frame/kdeconnect/fetch.py')
+fetch = importlib.util.module_from_spec(SPEC)
+SPEC.loader.exec_module(fetch)
+
+
+class VerifiedDownload(unittest.TestCase):
+    def test_remote_disconnect_retries_then_checks_hash(self):
+        data = b'pinned package'
+        digest = hashlib.sha256(data).hexdigest()
+        with patch.object(fetch.urllib.request, 'urlopen', side_effect=[
+                http.client.RemoteDisconnected('closed'), io.BytesIO(data)]) as open_url, \
+                patch.object(fetch.time, 'sleep') as sleep:
+            self.assertEqual(fetch.download_verified('https://example.invalid/package', digest), data)
+        self.assertEqual(open_url.call_count, 2)
+        sleep.assert_called_once_with(1)
+
+    def test_permanent_http_error_and_wrong_hash_fail_closed(self):
+        url = 'https://example.invalid/package'
+        missing = urllib.error.HTTPError(url, 404, 'missing', {}, None)
+        with patch.object(fetch.urllib.request, 'urlopen', side_effect=missing) as open_url, \
+                patch.object(fetch.time, 'sleep') as sleep:
+            with self.assertRaises(urllib.error.HTTPError):
+                fetch.download_verified(url, '0' * 64)
+        open_url.assert_called_once()
+        sleep.assert_not_called()
+        with patch.object(fetch.urllib.request, 'urlopen', return_value=io.BytesIO(b'changed')) as open_url:
+            with self.assertRaisesRegex(SystemExit, 'checksum mismatch'):
+                fetch.download_verified(url, '0' * 64)
+        open_url.assert_called_once()
+
+    def test_exhausted_transient_error_is_not_silenced(self):
+        with patch.object(fetch.urllib.request, 'urlopen', side_effect=http.client.RemoteDisconnected('closed')) as open_url, \
+                patch.object(fetch.time, 'sleep') as sleep:
+            with self.assertRaises(http.client.RemoteDisconnected):
+                fetch.download_verified('https://example.invalid/package', '0' * 64)
+        self.assertEqual(open_url.call_count, 3)
+        self.assertEqual(sleep.call_count, 2)
+
+
+if __name__ == '__main__':
+    unittest.main()