Substantially increase coverage in BOLT11 deserialization fuzzer

diff --git a/fuzz/src/bolt11_deser.rs b/fuzz/src/bolt11_deser.rs
index 105235a7bf0ef23fdad65ff81d8d15114a915eda..d2c0ab590036faba9f81c5b85ab9c768da5302bf 100644 (file)
--- a/fuzz/src/bolt11_deser.rs
+++ b/fuzz/src/bolt11_deser.rs
@@ -7,26 +7,62 @@
 // You may not use this file except in accordance with one or both of these
 // licenses.
 
-use bitcoin::bech32::{u5, FromBase32, ToBase32};
 use crate::utils::test_logger;
-use lightning_invoice::RawDataPart;
+use bitcoin::bech32::{u5, FromBase32, ToBase32};
+use bitcoin::secp256k1::{Secp256k1, SecretKey};
+use lightning_invoice::{
+       Bolt11Invoice, RawBolt11Invoice, RawDataPart, RawHrp, RawTaggedField, TaggedField,
+};
+use std::str::FromStr;
 
 #[inline]
 pub fn do_test<Out: test_logger::Output>(data: &[u8], _out: Out) {
-       let bech32 = data.iter().map(|x| u5::try_from_u8(x % 32).unwrap()).collect::<Vec<_>>();
-       let invoice = match RawDataPart::from_base32(&bech32) {
-               Ok(invoice) => invoice,
-               Err(_) => return,
-       };
-
-       // Our encoding is not worse than the input
-       assert!(invoice.to_base32().len() <= bech32.len());
-
-       // Our serialization is loss-less
-       assert_eq!(
-               RawDataPart::from_base32(&invoice.to_base32()).expect("faild parsing out own encoding"),
-               invoice
-       );
+       // Read a fake HRP length byte
+       let hrp_len = std::cmp::min(*data.get(0).unwrap_or(&0) as usize, data.len());
+       if let Ok(s) = std::str::from_utf8(&data[..hrp_len]) {
+               let hrp = match RawHrp::from_str(s) {
+                       Ok(hrp) => hrp,
+                       Err(_) => return,
+               };
+               let bech32 =
+                       data.iter().skip(hrp_len).map(|x| u5::try_from_u8(x % 32).unwrap()).collect::<Vec<_>>();
+               let invoice_data = match RawDataPart::from_base32(&bech32) {
+                       Ok(invoice) => invoice,
+                       Err(_) => return,
+               };
+
+               // Our data encoding is not worse than the input
+               assert!(invoice_data.to_base32().len() <= bech32.len());
+
+               // Our data serialization is loss-less
+               assert_eq!(
+                       RawDataPart::from_base32(&invoice_data.to_base32())
+                               .expect("faild parsing out own encoding"),
+                       invoice_data
+               );
+
+               if invoice_data.tagged_fields.iter().any(|field| {
+                       matches!(field, RawTaggedField::KnownSemantics(TaggedField::PayeePubKey(_)))
+               }) {
+                       // We could forge a signature using the fact that signing is insecure in fuzz mode, but
+                       // easier to just skip and rely on the fact that no-PayeePubKey invoices do pubkey
+                       // recovery
+                       return;
+               }
+
+               let raw_invoice = RawBolt11Invoice { hrp, data: invoice_data };
+               let signed_raw_invoice = match raw_invoice.sign(|hash| {
+                       let private_key = SecretKey::from_slice(&[42; 32]).unwrap();
+                       Ok::<_, ()>(Secp256k1::new().sign_ecdsa_recoverable(hash, &private_key))
+               }) {
+                       Ok(inv) => inv,
+                       Err(_) => return,
+               };
+
+               if let Ok(invoice) = Bolt11Invoice::from_signed(signed_raw_invoice) {
+                       invoice.amount_milli_satoshis();
+               }
+       }
 }
 
 pub fn bolt11_deser_test<Out: test_logger::Output>(data: &[u8], out: Out) {