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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::ops::Deref;
use neqo_common::Encoder;
use crate::{huffman::encode_huffman, prefix::Prefix};
#[derive(Default, Debug, PartialEq)]
pub(crate) struct QpackData {
buf: Vec<u8>,
}
impl QpackData {
pub fn len(&self) -> usize {
self.buf.len()
}
fn write_byte(&mut self, b: u8) {
self.buf.push(b);
}
pub fn encode_varint(&mut self, i: u64) {
let mut enc = Encoder::default();
enc.encode_varint(i);
self.buf.append(&mut enc.into());
}
pub(crate) fn encode_prefixed_encoded_int(&mut self, prefix: Prefix, mut val: u64) -> usize {
let first_byte_max: u8 = if prefix.len() == 0 {
0xff
} else {
(1 << (8 - prefix.len())) - 1
};
if val < u64::from(first_byte_max) {
let v = u8::try_from(val).unwrap();
self.write_byte((prefix.prefix() & !first_byte_max) | v);
return 1;
}
self.write_byte(prefix.prefix() | first_byte_max);
val -= u64::from(first_byte_max);
let mut written = 1;
let mut done = false;
while !done {
let mut b = u8::try_from(val & 0x7f).unwrap();
val >>= 7;
if val > 0 {
b |= 0x80;
} else {
done = true;
}
self.write_byte(b);
written += 1;
}
written
}
pub fn encode_literal(&mut self, use_huffman: bool, prefix: Prefix, value: &[u8]) {
let real_prefix = Prefix::new(
if use_huffman {
prefix.prefix() | (0x80 >> prefix.len())
} else {
prefix.prefix()
},
prefix.len() + 1,
);
if use_huffman {
let encoded = encode_huffman(value);
self.encode_prefixed_encoded_int(real_prefix, u64::try_from(encoded.len()).unwrap());
self.write_bytes(&encoded);
} else {
self.encode_prefixed_encoded_int(real_prefix, u64::try_from(value.len()).unwrap());
self.write_bytes(value);
}
}
pub fn write_bytes(&mut self, buf: &[u8]) {
self.buf.extend_from_slice(buf);
}
pub fn read(&mut self, r: usize) {
assert!(
r <= self.buf.len(),
"want to set more bytes read than remain in the buffer."
);
self.buf = self.buf.split_off(r);
}
}
impl Deref for QpackData {
type Target = [u8];
fn deref(&self) -> &Self::Target {
&self.buf
}
}
#[cfg(test)]
mod tests {
use super::{Prefix, QpackData};
#[test]
fn test_encode_prefixed_encoded_int_1() {
let mut d = QpackData::default();
d.encode_prefixed_encoded_int(Prefix::new(0xC0, 2), 5);
assert_eq!(d[..], [0xc5]);
}
#[test]
fn test_encode_prefixed_encoded_int_2() {
let mut d = QpackData::default();
d.encode_prefixed_encoded_int(Prefix::new(0xC0, 2), 65);
assert_eq!(d[..], [0xff, 0x02]);
}
#[test]
fn test_encode_prefixed_encoded_int_3() {
let mut d = QpackData::default();
d.encode_prefixed_encoded_int(Prefix::new(0xC0, 2), 100_000);
assert_eq!(d[..], [0xff, 0xe1, 0x8c, 0x06]);
}
#[test]
fn max_int() {
let mut d = QpackData::default();
d.encode_prefixed_encoded_int(Prefix::new(0x80, 1), u64::MAX);
assert_eq!(
d[..],
[0xff, 0x80, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x01]
);
}
const VALUE: &[u8] = b"custom-key";
const LITERAL: &[u8] = &[
0xca, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d, 0x2d, 0x6b, 0x65, 0x79,
];
const LITERAL_HUFFMAN: &[u8] = &[0xe8, 0x25, 0xa8, 0x49, 0xe9, 0x5b, 0xa9, 0x7d, 0x7f];
#[test]
fn test_encode_literal() {
let mut d = QpackData::default();
d.encode_literal(false, Prefix::new(0xC0, 2), VALUE);
assert_eq!(&&d[..], &LITERAL);
}
#[test]
fn test_encode_literal_huffman() {
let mut d = QpackData::default();
d.encode_literal(true, Prefix::new(0xC0, 2), VALUE);
assert_eq!(&&d[..], &LITERAL_HUFFMAN);
}
}