84 lines
4.2 KiB
Rust
84 lines
4.2 KiB
Rust
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use std::{cmp, convert::TryFrom, fmt};
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/// A 512-byte _Memo_ field 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, Copy)]
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pub struct Memo([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(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(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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let output: String;
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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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match std::str::from_utf8(&self.0[..]) {
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Ok(memo) => output = String::from(memo),
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_ => output = 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 memo = Memo(
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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 it's 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 it\\\'s 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(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 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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