145 lines
3.7 KiB
Rust
145 lines
3.7 KiB
Rust
extern crate serde;
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use std::fmt;
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use serde::{de, Serializer, Deserializer};
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static CHARS: &'static[u8] = b"0123456789abcdef";
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fn to_hex<'a>(v: &'a mut [u8], bytes: &[u8], skip_leading_zero: bool) -> &'a str {
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assert!(v.len() > 1 + bytes.len() * 2);
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v[0] = b'0';
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v[1] = b'x';
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let mut idx = 2;
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let first_nibble = bytes[0] >> 4;
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if first_nibble != 0 || !skip_leading_zero {
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v[idx] = CHARS[first_nibble as usize];
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idx += 1;
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}
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v[idx] = CHARS[(bytes[0] & 0xf) as usize];
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idx += 1;
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for &byte in bytes.iter().skip(1) {
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v[idx] = CHARS[(byte >> 4) as usize];
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v[idx + 1] = CHARS[(byte & 0xf) as usize];
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idx += 2;
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}
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::std::str::from_utf8(&v[0..idx]).expect("All characters are coming from CHARS")
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}
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/// Serializes a slice of bytes.
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pub fn serialize<S>(slice: &mut [u8], bytes: &[u8], serializer: S) -> Result<S::Ok, S::Error> where
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S: Serializer,
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{
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serializer.serialize_str(to_hex(slice, bytes, false))
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}
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/// Serialize a slice of bytes as uint.
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///
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/// The representation will have all leading zeros trimmed.
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pub fn serialize_uint<S>(slice: &mut [u8], bytes: &[u8], serializer: S) -> Result<S::Ok, S::Error> where
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S: Serializer,
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{
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let non_zero = bytes.iter().take_while(|b| **b == 0).count();
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let bytes = &bytes[non_zero..];
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if bytes.is_empty() {
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return serializer.serialize_str("0x0");
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}
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serializer.serialize_str(to_hex(slice, bytes, true))
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}
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/// Expected length of bytes vector.
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#[derive(Debug, PartialEq, Eq)]
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pub enum ExpectedLen<'a> {
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/// Exact length in bytes.
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Exact(&'a mut [u8]),
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/// A bytes length between (min; slice.len()].
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Between(usize, &'a mut [u8]),
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}
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impl<'a> fmt::Display for ExpectedLen<'a> {
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fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
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match *self {
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ExpectedLen::Exact(ref v) => write!(fmt, "length of {}", v.len() * 2),
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ExpectedLen::Between(min, ref v) => write!(fmt, "length between ({}; {}]", min * 2, v.len() * 2),
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}
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}
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}
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/// Deserialize into vector of bytes with additional size check.
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/// Returns number of bytes written.
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pub fn deserialize_check_len<'a, 'de, D>(deserializer: D, len: ExpectedLen<'a>) -> Result<usize, D::Error> where
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D: Deserializer<'de>,
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{
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struct Visitor<'a> {
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len: ExpectedLen<'a>,
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}
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impl<'a, 'b> de::Visitor<'b> for Visitor<'a> {
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type Value = usize;
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fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
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write!(formatter, "a 0x-prefixed hex string with {}", self.len)
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}
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fn visit_str<E: de::Error>(self, v: &str) -> Result<Self::Value, E> {
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if v.len() < 2 || &v[0..2] != "0x" {
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return Err(E::custom("prefix is missing"))
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}
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let is_len_valid = match self.len {
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ExpectedLen::Exact(ref slice) => v.len() == 2 * slice.len() + 2,
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ExpectedLen::Between(min, ref slice) => v.len() <= 2 * slice.len() + 2 && v.len() > 2 * min + 2,
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};
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if !is_len_valid {
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return Err(E::invalid_length(v.len() - 2, &self))
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}
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let bytes = match self.len {
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ExpectedLen::Exact(slice) => slice,
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ExpectedLen::Between(_, slice) => slice,
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};
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let mut modulus = v.len() % 2;
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let mut buf = 0;
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let mut pos = 0;
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for (idx, byte) in v.bytes().enumerate().skip(2) {
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buf <<= 4;
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match byte {
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b'A'...b'F' => buf |= byte - b'A' + 10,
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b'a'...b'f' => buf |= byte - b'a' + 10,
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b'0'...b'9' => buf |= byte - b'0',
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b' '|b'\r'|b'\n'|b'\t' => {
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buf >>= 4;
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continue
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}
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_ => {
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let ch = v[idx..].chars().next().unwrap();
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return Err(E::custom(&format!("invalid hex character: {}, at {}", ch, idx)))
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}
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}
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modulus += 1;
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if modulus == 2 {
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modulus = 0;
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bytes[pos] = buf;
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pos += 1;
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}
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}
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Ok(pos)
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}
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fn visit_string<E: de::Error>(self, v: String) -> Result<Self::Value, E> {
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self.visit_str(&v)
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}
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}
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deserializer.deserialize_str(Visitor { len })
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}
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