filter: a failed blocklist download names its phase, cause, status, bytes and elapsed time

src/upstream/doh_client.zig

@@ -226,43 +226,12 @@ const Connection = std.http.Client.Connection;
 const Request = std.http.Client.Request;
 const Response = std.http.Client.Response;
 
-/// `std.Io.Writer` collapses every send failure to `error.WriteFailed` and
-/// stashes the cause on the connection's socket writer. Unwrapping it is what
-/// keeps `error.Canceled` and the local resource errors out of the peer fault
-/// group, exactly as `concreteWrite` does for DoT.
-fn sendCause(req: *const Request, err: anyerror) anyerror {
-    if (err != error.WriteFailed) return err;
-    const connection = req.connection orelse return err;
-    return connection.stream_writer.err orelse err;
-}
-
-/// `receiveHead` collapses a transport failure to `error.ReadFailed` and names
-/// `Connection.getReadError` as the accessor for the concrete cause.
-fn headCause(req: *const Request, err: anyerror) anyerror {
-    if (err != error.ReadFailed) return err;
-    const connection = req.connection orelse return err;
-    return readCause(connection, err);
-}
-
-/// A body read reports two different kinds of failure through the same
-/// `error.ReadFailed`. An HTTP framing fault lands on the response, and only a
-/// read that never reached the framing leaves the connection's cause, so the
-/// response is consulted first.
-fn bodyCause(resp: *const Response, err: anyerror) anyerror {
-    if (err != error.ReadFailed) return err;
-    if (resp.bodyErr()) |cause| return cause;
-    const connection = resp.request.connection orelse return err;
-    return readCause(connection, err);
-}
-
-/// `Connection.getReadError` reads the socket reader's stashed cause with `.?`.
-/// On a plain connection that is its only source, so calling it with nothing
-/// stashed would panic rather than return null; the guard keeps this unwrap
-/// total on the path this client can reach without TLS.
-fn readCause(connection: *const Connection, err: anyerror) anyerror {
-    if (connection.protocol == .plain and connection.stream_reader.err == null) return err;
-    return connection.getReadError() orelse err;
-}
+// The unwraps live in `transport.zig` because the blocklist fetcher needs the
+// same concrete causes. They are aliased rather than qualified so the call
+// sites and the tests below read as they did when they were local.
+const sendCause = transport.sendCause;
+const headCause = transport.headCause;
+const bodyCause = transport.bodyCause;
 
 /// RFC 8484 §6: the response media type is `application/dns-message`. The
 /// header may carry parameters (`; charset=…`) and the type is case-insensitive