use the exported magic for detecting DTX

Author: dmissmann

ios/debugproxy/utun/connection.go

@@ -108,7 +108,7 @@ func parseConnectionData(outgoing string, incoming string) error {
 			outErr := decodeHttp2(outgoing.w, outFile, true)
 			inErr := decodeHttp2(incoming.w, inFile, false)
 			if err := errors.Join(outErr, inErr); err != nil {
-				//return err
+				return err
 			}
 			return parseConnectionData(outgoing.p, incoming.p)
 		})

ios/debugproxy/utun/decoding.go

@@ -41,11 +41,12 @@ func detectType(r io.ReadSeeker) contentType {
 	if string(b) == "PRI " {
 		return http2
 	}
-	i := binary.LittleEndian.Uint32(b)
-	if i == 0x29b00b92 {
+	le := binary.LittleEndian.Uint32(b)
+	be := binary.BigEndian.Uint32(b)
+	if le == 0x29b00b92 {
 		return remoteXpc
 	}
-	if string(b[:3]) == "y[=" {
+	if be == dtx.DtxMessageMagic {
 		return remoteDtx
 	}