monero: added tx extra variants padding and mysterious minergate (#510)

* monero: read/write tx extra padding

* monero: read/write tx extra mysterious minergate variant

* Clippy

* monero: add tx extra test for minergate + pub key

* BufRead

---------

Co-authored-by: Luke Parker <lukeparker5132@gmail.com>

coins/monero/src/tests/extra.rs

@@ -0,0 +1,158 @@
+use crate::{
+  wallet::{ExtraField, Extra, extra::MAX_TX_EXTRA_PADDING_COUNT},
+  serialize::write_varint,
+};
+
+use curve25519_dalek::edwards::{EdwardsPoint, CompressedEdwardsY};
+
+// Borrowed tests from
+// https://github.com/monero-project/monero/blob/ac02af92867590ca80b2779a7bbeafa99ff94dcb/
+//   tests/unit_tests/test_tx_utils.cpp
+
+const PUB_KEY_BYTES: [u8; 33] = [
+  1, 30, 208, 98, 162, 133, 64, 85, 83, 112, 91, 188, 89, 211, 24, 131, 39, 154, 22, 228, 80, 63,
+  198, 141, 173, 111, 244, 183, 4, 149, 186, 140, 230,
+];
+
+fn pub_key() -> EdwardsPoint {
+  CompressedEdwardsY(PUB_KEY_BYTES[1 .. PUB_KEY_BYTES.len()].try_into().expect("invalid pub key"))
+    .decompress()
+    .unwrap()
+}
+
+fn test_write_buf(extra: &Extra, buf: &[u8]) {
+  let mut w: Vec<u8> = vec![];
+  Extra::write(extra, &mut w).unwrap();
+  assert_eq!(buf, w);
+}
+
+#[test]
+fn empty_extra() {
+  let buf: Vec<u8> = vec![];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert!(extra.0.is_empty());
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn padding_only_size_1() {
+  let buf: Vec<u8> = vec![0];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::Padding(1)]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn padding_only_size_2() {
+  let buf: Vec<u8> = vec![0, 0];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::Padding(2)]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn padding_only_max_size() {
+  let buf: Vec<u8> = vec![0; MAX_TX_EXTRA_PADDING_COUNT];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::Padding(MAX_TX_EXTRA_PADDING_COUNT)]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn padding_only_exceed_max_size() {
+  let buf: Vec<u8> = vec![0; MAX_TX_EXTRA_PADDING_COUNT + 1];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert!(extra.0.is_empty());
+}
+
+#[test]
+fn invalid_padding_only() {
+  let buf: Vec<u8> = vec![0, 42];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert!(extra.0.is_empty());
+}
+
+#[test]
+fn pub_key_only() {
+  let buf: Vec<u8> = PUB_KEY_BYTES.to_vec();
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::PublicKey(pub_key())]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn extra_nonce_only() {
+  let buf: Vec<u8> = vec![2, 1, 42];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::Nonce(vec![42])]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn extra_nonce_only_wrong_size() {
+  let mut buf: Vec<u8> = vec![0; 20];
+  buf[0] = 2;
+  buf[1] = 255;
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert!(extra.0.is_empty());
+}
+
+#[test]
+fn pub_key_and_padding() {
+  let mut buf: Vec<u8> = PUB_KEY_BYTES.to_vec();
+  buf.extend([
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+  ]);
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::PublicKey(pub_key()), ExtraField::Padding(76)]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn pub_key_and_invalid_padding() {
+  let mut buf: Vec<u8> = PUB_KEY_BYTES.to_vec();
+  buf.extend([0, 1]);
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::PublicKey(pub_key())]);
+}
+
+#[test]
+fn extra_mysterious_minergate_only() {
+  let buf: Vec<u8> = vec![222, 1, 42];
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::MysteriousMinergate(vec![42])]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn extra_mysterious_minergate_only_large() {
+  let mut buf: Vec<u8> = vec![222];
+  write_varint(&512u64, &mut buf).unwrap();
+  buf.extend_from_slice(&vec![0; 512]);
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(extra.0, vec![ExtraField::MysteriousMinergate(vec![0; 512])]);
+  test_write_buf(&extra, &buf);
+}
+
+#[test]
+fn extra_mysterious_minergate_only_wrong_size() {
+  let mut buf: Vec<u8> = vec![0; 20];
+  buf[0] = 222;
+  buf[1] = 255;
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert!(extra.0.is_empty());
+}
+
+#[test]
+fn extra_mysterious_minergate_and_pub_key() {
+  let mut buf: Vec<u8> = vec![222, 1, 42];
+  buf.extend(PUB_KEY_BYTES.to_vec());
+  let extra = Extra::read::<&[u8]>(&mut buf.as_ref()).unwrap();
+  assert_eq!(
+    extra.0,
+    vec![ExtraField::MysteriousMinergate(vec![42]), ExtraField::PublicKey(pub_key())]
+  );
+  test_write_buf(&extra, &buf);
+}