Fuzz test for parsing bech32-encoded Offer

An offer is serialized as a TLV stream and encoded in bech32 without a
checksum. Add a fuzz test that parses the bech32-encoded TLV stream and
deserializes the underlying Offer before serializing it and re-encoding
it. Then compare the original Offer with one obtained by parsing the
re-encoded TLV stream.

Author: jkczyz

fuzz/src/bin/gen_target.sh

@@ -9,6 +9,7 @@ GEN_TEST() {
 GEN_TEST chanmon_deser
 GEN_TEST chanmon_consistency
 GEN_TEST full_stack
+GEN_TEST offer_deser
 GEN_TEST onion_message
 GEN_TEST peer_crypt
 GEN_TEST process_network_graph

fuzz/src/bin/offer_deser_target.rs

@@ -0,0 +1,113 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+// This file is auto-generated by gen_target.sh based on target_template.txt
+// To modify it, modify target_template.txt and run gen_target.sh instead.
+
+#![cfg_attr(feature = "libfuzzer_fuzz", no_main)]
+
+#[cfg(not(fuzzing))]
+compile_error!("Fuzz targets need cfg=fuzzing");
+
+extern crate lightning_fuzz;
+use lightning_fuzz::offer_deser::*;
+
+#[cfg(feature = "afl")]
+#[macro_use] extern crate afl;
+#[cfg(feature = "afl")]
+fn main() {
+	fuzz!(|data| {
+		offer_deser_run(data.as_ptr(), data.len());
+	});
+}
+
+#[cfg(feature = "honggfuzz")]
+#[macro_use] extern crate honggfuzz;
+#[cfg(feature = "honggfuzz")]
+fn main() {
+	loop {
+		fuzz!(|data| {
+			offer_deser_run(data.as_ptr(), data.len());
+		});
+	}
+}
+
+#[cfg(feature = "libfuzzer_fuzz")]
+#[macro_use] extern crate libfuzzer_sys;
+#[cfg(feature = "libfuzzer_fuzz")]
+fuzz_target!(|data: &[u8]| {
+	offer_deser_run(data.as_ptr(), data.len());
+});
+
+#[cfg(feature = "stdin_fuzz")]
+fn main() {
+	use std::io::Read;
+
+	let mut data = Vec::with_capacity(8192);
+	std::io::stdin().read_to_end(&mut data).unwrap();
+	offer_deser_run(data.as_ptr(), data.len());
+}
+
+#[test]
+fn run_test_cases() {
+	use std::fs;
+	use std::io::Read;
+	use lightning_fuzz::utils::test_logger::StringBuffer;
+
+	use std::sync::{atomic, Arc};
+	{
+		let data: Vec<u8> = vec![0];
+		offer_deser_run(data.as_ptr(), data.len());
+	}
+	let mut threads = Vec::new();
+	let threads_running = Arc::new(atomic::AtomicUsize::new(0));
+	if let Ok(tests) = fs::read_dir("test_cases/offer_deser") {
+		for test in tests {
+			let mut data: Vec<u8> = Vec::new();
+			let path = test.unwrap().path();
+			fs::File::open(&path).unwrap().read_to_end(&mut data).unwrap();
+			threads_running.fetch_add(1, atomic::Ordering::AcqRel);
+
+			let thread_count_ref = Arc::clone(&threads_running);
+			let main_thread_ref = std::thread::current();
+			threads.push((path.file_name().unwrap().to_str().unwrap().to_string(),
+				std::thread::spawn(move || {
+					let string_logger = StringBuffer::new();
+
+					let panic_logger = string_logger.clone();
+					let res = if ::std::panic::catch_unwind(move || {
+						offer_deser_test(&data, panic_logger);
+					}).is_err() {
+						Some(string_logger.into_string())
+					} else { None };
+					thread_count_ref.fetch_sub(1, atomic::Ordering::AcqRel);
+					main_thread_ref.unpark();
+					res
+				})
+			));
+			while threads_running.load(atomic::Ordering::Acquire) > 32 {
+				std::thread::park();
+			}
+		}
+	}
+	let mut failed_outputs = Vec::new();
+	for (test, thread) in threads.drain(..) {
+		if let Some(output) = thread.join().unwrap() {
+			println!("\nOutput of {}:\n{}\n", test, output);
+			failed_outputs.push(test);
+		}
+	}
+	if !failed_outputs.is_empty() {
+		println!("Test cases which failed: ");
+		for case in failed_outputs {
+			println!("{}", case);
+		}
+		panic!();
+	}
+}

fuzz/src/lib.rs

@@ -18,6 +18,7 @@ pub mod chanmon_deser;
 pub mod chanmon_consistency;
 pub mod full_stack;
 pub mod indexedmap;
+pub mod offer_deser;
 pub mod onion_message;
 pub mod peer_crypt;
 pub mod process_network_graph;

fuzz/src/offer_deser.rs

@@ -0,0 +1,71 @@
+// This file is Copyright its original authors, visible in version control
+// history.
+//
+// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
+// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
+// You may not use this file except in accordance with one or both of these
+// licenses.
+
+use bitcoin::secp256k1::{KeyPair, PublicKey, Secp256k1, SecretKey};
+use crate::utils::test_logger;
+use core::convert::Infallible;
+use lightning::offers::invoice_request::UnsignedInvoiceRequest;
+use lightning::offers::offer::{Amount, Offer, Quantity};
+use lightning::offers::parse::SemanticError;
+use lightning::util::ser::Writeable;
+
+#[inline]
+pub fn do_test<Out: test_logger::Output>(data: &[u8], _out: Out) {
+	if let Ok(bech32_encoded) = std::str::from_utf8(data) {
+		if let Ok(offer) = bech32_encoded.parse::<Offer>() {
+			let bech32_encoded = offer.to_string();
+			assert_eq!(offer, bech32_encoded.parse::<Offer>().unwrap());
+
+			let secp_ctx = Secp256k1::new();
+			let keys =
+				KeyPair::from_secret_key(&secp_ctx, &SecretKey::from_slice(&[42; 32]).unwrap());
+			let pubkey = PublicKey::from(keys);
+			let mut buffer = Vec::new();
+
+			if let Ok(invoice_request) = build_response(&offer, pubkey) {
+				invoice_request
+					.sign::<_, Infallible>(
+						|digest| Ok(secp_ctx.sign_schnorr_no_aux_rand(digest, &keys))
+					)
+					.unwrap()
+					.write(&mut buffer)
+					.unwrap();
+			}
+		}
+	}
+}
+
+fn build_response<'a>(
+	offer: &'a Offer, pubkey: PublicKey
+) -> Result<UnsignedInvoiceRequest<'a>, SemanticError> {
+	let mut builder = offer.request_invoice(vec![42; 64], pubkey)?;
+
+	builder = match offer.amount() {
+		None => builder.amount_msats(1000)?,
+		Some(Amount::Bitcoin { amount_msats }) => builder.amount_msats(amount_msats + 1)?,
+		Some(Amount::Currency { .. }) => return Err(SemanticError::UnsupportedCurrency),
+	};
+
+	builder = match offer.supported_quantity() {
+		Quantity::Bounded(n) if n.get() != 1 => builder.quantity(n.get())?,
+		Quantity::Bounded(_) => builder,
+		Quantity::Unbounded => builder.quantity(10)?,
+	};
+
+	builder.build()
+}
+
+pub fn offer_deser_test<Out: test_logger::Output>(data: &[u8], out: Out) {
+	do_test(data, out);
+}
+
+#[no_mangle]
+pub extern "C" fn offer_deser_run(data: *const u8, datalen: usize) {
+	do_test(unsafe { std::slice::from_raw_parts(data, datalen) }, test_logger::DevNull {});
+}

fuzz/targets.h

@@ -2,6 +2,7 @@
 void chanmon_deser_run(const unsigned char* data, size_t data_len);
 void chanmon_consistency_run(const unsigned char* data, size_t data_len);
 void full_stack_run(const unsigned char* data, size_t data_len);
+void offer_deser_run(const unsigned char* data, size_t data_len);
 void onion_message_run(const unsigned char* data, size_t data_len);
 void peer_crypt_run(const unsigned char* data, size_t data_len);
 void process_network_graph_run(const unsigned char* data, size_t data_len);

lightning/src/offers/offer.rs

@@ -242,7 +242,7 @@ impl OfferBuilder {
 ///
 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 /// [`Invoice`]: crate::offers::invoice::Invoice
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub struct Offer {
 	// The serialized offer. Needed when creating an `InvoiceRequest` if the offer contains unknown
 	// fields.
@@ -254,7 +254,7 @@ pub struct Offer {
 ///
 /// [`InvoiceRequest`]: crate::offers::invoice_request::InvoiceRequest
 /// [`Invoice`]: crate::offers::invoice::Invoice
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub(super) struct OfferContents {
 	chains: Option<Vec<ChainHash>>,
 	metadata: Option<Vec<u8>>,