90 lines
4.5 KiB
Rust
90 lines
4.5 KiB
Rust
use std::{cmp, fmt};
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/// A 512-byte (plaintext) memo associated with a note, as described in
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/// [protocol specification §5.5][ps].
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///
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/// The _Memo_ field of a note is a plaintext type; the parent note is
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/// what is encrypted and stored on the blockchain. The underlying
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/// usage of the memo field is by agreement between the sender and
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/// recipient of the note.
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///
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/// [ps]: https://zips.z.cash/protocol/protocol.pdf#notept
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#[derive(Clone)]
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pub struct Memo(pub(crate) Box<[u8; 512]>);
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impl<'a> TryFrom<&'a [u8]> for Memo {
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type Error = &'static str;
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fn try_from(input: &'a [u8]) -> Result<Self, Self::Error> {
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let mut full_bytes = [0; 512];
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match input.len().cmp(&512) {
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cmp::Ordering::Less => {
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full_bytes[0..input.len()].copy_from_slice(input);
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Ok(Memo(Box::new(full_bytes)))
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}
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cmp::Ordering::Equal => {
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full_bytes[..].copy_from_slice(input);
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Ok(Memo(Box::new(full_bytes)))
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}
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cmp::Ordering::Greater => Err("Memos have a max length of 512 bytes."),
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}
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}
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}
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impl fmt::Debug for Memo {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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// This saves work but if the 'valid utf8 string' is just a
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// bunch of numbers, it prints them out like
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// 'Memo("\u{0}\u{0}..")', so. ¯\_(ツ)_/¯
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let output: String = match std::str::from_utf8(&self.0[..]) {
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Ok(memo) => String::from(memo),
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_ => hex::encode(&self.0[..]),
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};
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f.debug_tuple("Memo").field(&output).finish()
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}
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}
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#[test]
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fn memo_fmt() {
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let _init_guard = zebra_test::init();
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// Rust changed the escaping of ' between 1.52 and 1.53 (nightly-2021-04-14?),
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// so the memo string can't contain '
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//
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// TODO: rewrite this test so it doesn't depend on the exact debug format
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let memo = Memo(Box::new(
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*b"thiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiis \
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iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiis \
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aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa \
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veeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeryyyyyyyyyyyyyyyyyyyyyyyyyy \
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looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong \
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meeeeeeeeeeeeeeeeeeemooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo \
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but its just short enough!",
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));
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assert_eq!(format!("{memo:?}"),
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"Memo(\"thiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiis iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiis aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa veeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeryyyyyyyyyyyyyyyyyyyyyyyyyy looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong meeeeeeeeeeeeeeeeeeemooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo but its just short enough!\")"
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);
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let mut some_bytes = [0u8; 512];
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some_bytes[0] = 0xF6;
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assert_eq!(format!("{:?}", Memo(Box::new(some_bytes))),
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"Memo(\"f600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000\")"
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);
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}
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#[test]
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fn memo_from_string() {
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let _init_guard = zebra_test::init();
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let memo = Memo::try_from("foo bar baz".as_ref()).unwrap();
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let mut bytes = [0; 512];
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bytes[0..11].copy_from_slice(&[102, 111, 111, 32, 98, 97, 114, 32, 98, 97, 122]);
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assert!(memo.0.iter().eq(bytes.iter()));
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}
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