Safe-cast URLResponse in ProxyHTTPHandler

[ianegordon]

Summary

ProxyHTTPHandler.handleRequest force-unwrapped the URLResponse returned by URLSession.data(for:) as an HTTPURLResponse. If the session is configured with a custom URLProtocol, a file:// URL, or hits certain error paths, the response isn't guaranteed to be an HTTPURLResponse — the force cast traps and crashes the server actor.

Change

FlyingFox/Sources/Handlers/ProxyHTTPHandler.swift:

 public func handleRequest(_ request: HTTPRequest) async throws -> HTTPResponse {
     let req = try await makeURLRequest(for: request)
     let (data, response) = try await session.data(for: req)
-    return makeResponse(for: response as! HTTPURLResponse, data: data)
+    guard let httpResponse = response as? HTTPURLResponse else {
+        throw URLError(.badServerResponse)
+    }
+    return makeResponse(for: httpResponse, data: data)
 }

Test

New test in FlyingFox/Tests/Handlers/HTTPHandlerTests.swift uses a URLProtocol subclass that returns a plain (non-HTTP) URLResponse and asserts the handler throws URLError rather than crashing.

Test plan

• swift build clean.
• New test proxyHandler_ThrowsError_WhenResponseIsNotHTTPURLResponse passes.
• swift test — 405 tests across 49 suites pass (up from 404).

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.21%. Comparing base (d97e0e2) to head (1fc3a3e).
⚠️ Report is 7 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #203      +/-   ##
==========================================
+ Coverage   92.40%   93.21%   +0.80%     
==========================================
  Files          69       69              
  Lines        3543     4806    +1263     
==========================================
+ Hits         3274     4480    +1206     
- Misses        269      326      +57     

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[swhitty]

nice!