Added fuzzing helper library to increase code reusability and refactored first fuzz target

fuzz/fuzz_targets/fuzz_target_split_assemble.rs

@@ -1,53 +1,9 @@
 #![no_main]
 
-// This explicit "extern crate" is needed to make the linker aware of the
-// `libtock_alloc_init` symbol.
-extern crate lang_items;
-
-use arrayref::array_ref;
-use ctap2::ctap::hid::receive::MessageAssembler;
-use ctap2::ctap::hid::send::HidPacketIterator;
-use ctap2::ctap::hid::{HidPacket, Message};
+use fuzz_helper::split_assemble;
 use libfuzzer_sys::fuzz_target;
-use libtock_drivers::timer::Timestamp;
 
-const DUMMY_TIMESTAMP: Timestamp<isize> = Timestamp::from_ms(0);
-const PACKET_TYPE_MASK: u8 = 0x80;
-
-// Converts a byte slice into Message
-fn raw_to_message(data: &[u8]) -> Message {
-    if data.len() <= 4 {
-        let mut cid = [0; 4];
-        cid[..data.len()].copy_from_slice(data);
-        Message {
-            cid,
-            cmd: 0,
-            payload: vec![],
-        }
-    } else {
-        Message {
-            cid: array_ref!(data, 0, 4).clone(),
-            cmd: data[4],
-            payload: data[5..].to_vec(),
-        }
-    }
-}
-
-/* Fuzzing HID packets splitting and assembling functions*/
+// Fuzzing HID packets splitting and assembling functions.
 fuzz_target!(|data: &[u8]| {
-    let mut message = raw_to_message(data);
-    if let Some(hid_packet_iterator) = HidPacketIterator::new(message.clone()) {
-        let mut assembler = MessageAssembler::new();
-        let packets: Vec<HidPacket> = hid_packet_iterator.collect();
-        if let Some((last_packet, first_packets)) = packets.split_last() {
-            for packet in first_packets {
-                assert_eq!(assembler.parse_packet(packet, DUMMY_TIMESTAMP), Ok(None));
-            }
-            message.cmd &= !PACKET_TYPE_MASK;
-            assert_eq!(
-                assembler.parse_packet(last_packet, DUMMY_TIMESTAMP),
-                Ok(Some(message))
-            );
-        }
-    }
+    split_assemble(data);
 });