The buffer passed to fuzz_packet in a fuzz_tx fuzzer is always blank

[hexdefined]

If a simple fuzzer is created:

struct TestFuzzer();
impl Fuzzer for TestFuzzer {
    fn fuzz_packet(&self, frame_data: &mut [u8]) {
        println!("{:02x?}", frame_data);
    }
}

...and used with a FuzzInjector:

let device = FuzzInjector::new(device, TestFuzzer(), TestFuzzer());

...then the bytes of the received packets are printed, but the buffer for transmitted data is always blank at the time that fuzz_packet gets called.

[00, 00, 00, 00, 00, 00, 00, 00, ...

This seems to be because fuzz_packet() is called before f() in the TxToken implementation.

If the order is reversed, then the buffer contains data as expected.

--- a/src/phy/fuzz_injector.rs
+++ b/src/phy/fuzz_injector.rs
@@ -123,8 +123,9 @@ impl<'a, Tx: phy::TxToken, FTx: Fuzzer> phy::TxToken for TxToken<'a, Tx, FTx> {
     {
         let Self { fuzzer, token } = self;
         token.consume(timestamp, len, |mut buf| {
+            let result = f(buf);
             fuzzer.fuzz_packet(&mut buf);
-            f(buf)
+            result
         })
     }
 }

---

Disclaimer: I'm quite new to Rust, and haven't properly tested this patch. It works for my project, but it's possible I'm misunderstanding something.