# netstack fuzz targets

Six cargo-fuzz-style binaries (smoke-testable as plain command-line tools
when `cargo fuzz` is unavailable). The same input bytes are fed into the
smoltcp parsers that netstack uses for the Ethernet, ARP, IPv4, ICMP, TCP,
DHCP, and DNS protocols.

Each binary reads the payload from `argv[1]` (base64-decoded by the
test harness) and exercises both the `*_new_checked` (validated) and
`*_new_unchecked` (raw) parsers. A panic in either path indicates a parser
defect.

| Binary       | Parser                              |
|-------------|--------------------------------------|
| `fuzz_ethernet` | `EthernetFrame::new_checked/unchecked` |
| `fuzz_arp`      | `ArpPacket::new_checked/unchecked`   |
| `fuzz_icmp`     | `Ipv4Packet::new_checked/unchecked`  |
| `fuzz_tcp`      | `TcpPacket::new_checked/unchecked`   |
| `fuzz_dhcp`     | walk Ethernet → IPv4 → UDP           |
| `fuzz_dns`      | `UdpPacket::new_checked/unchecked`   |

Run with `cargo fuzz` (when the harness is configured) or directly:

```bash
cargo run --bin fuzz_tcp -- <bytes>
```

`[[bin]]` entries are in `netstack/Cargo.toml` so a plain
`cargo build` will produce all six executables. They are no-ops for
arbitrary input — any panic in this binary is a parser defect that
needs a fix in the smoltcp upstream or a Red Bear defensive check.