Fuzz for compatibility with bincode v1 (#498)

* Fuzz for compatibility with bincode v1

* Make AllTypes recursive

* Revert round trip test (add recursion to it too)

* Update fuzzer lockfile

* Adjust compat fuzzer to be stricter

* data doesn't need to be a &&[u8]

fuzz/Cargo.toml

@@ -10,6 +10,8 @@ cargo-fuzz = true
 
 [dependencies]
 libfuzzer-sys = "0.4"
+bincodev1 = {package = "bincode", version = "1.3.3"}
+serde = { version = "1.0.135", features = ["derive"] }
 
 [dependencies.bincode]
 path = ".."
@@ -23,3 +25,9 @@ name = "roundtrip"
 path = "fuzz_targets/roundtrip.rs"
 test = false
 doc = false
+
+[[bin]]
+name = "compat"
+path = "fuzz_targets/compat.rs"
+test = false
+doc = false

fuzz/fuzz_targets/compat.rs

@@ -0,0 +1,55 @@
+#![no_main]
+use libfuzzer_sys::fuzz_target;
+
+use std::collections::{BTreeMap, BTreeSet, VecDeque};
+use std::ffi::CString;
+use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
+use std::num::{NonZeroI128, NonZeroI32, NonZeroU128, NonZeroU32};
+use std::path::PathBuf;
+use std::time::{Duration, SystemTime};
+
+#[derive(bincode::Decode, bincode::Encode, PartialEq, Debug, serde::Serialize, serde::Deserialize, Eq, PartialOrd, Ord)]
+enum AllTypes {
+    BTreeMap(BTreeMap<u8, AllTypes>),
+    BTreeSet(BTreeSet<AllTypes>),
+    VecDeque(VecDeque<AllTypes>),
+    Vec(Vec<u8>),
+    String(String),
+    Box(Box<u8>),
+    BoxSlice(Box<[u8]>),
+    CString(CString),
+    SystemTime(SystemTime),
+    Duration(Duration),
+    PathBuf(PathBuf),
+    IpAddr(IpAddr),
+    Ipv4Addr(Ipv4Addr),
+    Ipv6Addr(Ipv6Addr),
+    SocketAddr(SocketAddr),
+    SocketAddrV4(SocketAddrV4),
+    SocketAddrV6(SocketAddrV6),
+    NonZeroU32(NonZeroU32),
+    NonZeroI32(NonZeroI32),
+    NonZeroU128(NonZeroU128),
+    NonZeroI128(NonZeroI128),
+    I128(i128),
+    I8(i8),
+    U128(u128),
+    U8(u8),
+    // Cow(Cow<'static, [u8]>), Blocked, see comment on decode
+}
+
+fuzz_target!(|data: &[u8]| {
+    let config = bincode::config::legacy().with_limit::<1024>();
+    #[allow(deprecated)]
+    let mut configv1 = bincodev1::config();
+    configv1.limit(1024);
+    let bincode_v1: Result<AllTypes, _> = configv1.deserialize(data);
+    let bincode_v2: Result<(AllTypes, _), _> = bincode::decode_from_slice(data, config);
+
+    if bincode_v1.as_ref().ok() != bincode_v2.as_ref().ok().map(|x| &x.0) {
+        println!("Bytes:      {:?}", data);
+        println!("Bincode V1: {:?}", bincode_v1);
+        println!("Bincode V2: {:?}", bincode_v2);
+        panic!("failed equality check");
+    }
+});

fuzz/fuzz_targets/roundtrip.rs

@@ -15,13 +15,13 @@ enum AllTypes {
     BTreeMap(BTreeMap<u8, u8>),
     HashMap(HashMap<u8, u8>),
     BTreeSet(BTreeSet<u8>),
-    VecDeque(VecDeque<u8>),
-    Vec(Vec<u8>),
+    VecDeque(VecDeque<AllTypes>),
+    Vec(Vec<AllTypes>),
     String(String),
-    Box(Box<u8>),
-    BoxSlice(Box<[u8]>),
-    Rc(Rc<u8>),
-    Arc(Arc<u8>),
+    Box(Box<AllTypes>),
+    BoxSlice(Box<[AllTypes]>),
+    Rc(Rc<AllTypes>),
+    Arc(Arc<AllTypes>),
     CString(CString),
     SystemTime(SystemTime),
     Duration(Duration),