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https://github.com/actix/actix-web.git
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76 lines
2.2 KiB
Rust
76 lines
2.2 KiB
Rust
//! This is code from [Tungstenite project](https://github.com/snapview/tungstenite-rs)
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/// Mask/unmask a frame.
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#[inline]
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pub fn apply_mask(buf: &mut [u8], mask: [u8; 4]) {
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apply_mask_fast32(buf, mask)
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}
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/// A safe unoptimized mask application.
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#[inline]
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fn apply_mask_fallback(buf: &mut [u8], mask: [u8; 4]) {
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for (i, byte) in buf.iter_mut().enumerate() {
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*byte ^= mask[i & 3];
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}
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}
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/// Faster version of `apply_mask()` which operates on 4-byte blocks.
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#[inline]
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pub fn apply_mask_fast32(buf: &mut [u8], mask: [u8; 4]) {
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let mask_u32 = u32::from_ne_bytes(mask);
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// SAFETY:
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//
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// buf is a valid slice borrowed mutably from bytes::BytesMut.
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//
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// un aligned prefix and suffix would be mask/unmask per byte.
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// proper aligned middle slice goes into fast path and operates on 4-byte blocks.
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let (prefix, words, suffix) = unsafe { buf.align_to_mut::<u32>() };
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apply_mask_fallback(prefix, mask);
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let head = prefix.len() & 3;
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let mask_u32 = if head > 0 {
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if cfg!(target_endian = "big") {
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mask_u32.rotate_left(8 * head as u32)
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} else {
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mask_u32.rotate_right(8 * head as u32)
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}
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} else {
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mask_u32
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};
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for word in words.iter_mut() {
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*word ^= mask_u32;
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}
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apply_mask_fallback(suffix, mask_u32.to_ne_bytes());
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_apply_mask() {
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let mask = [0x6d, 0xb6, 0xb2, 0x80];
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let unmasked = vec![
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0xf3, 0x00, 0x01, 0x02, 0x03, 0x80, 0x81, 0x82, 0xff, 0xfe, 0x00, 0x17, 0x74, 0xf9,
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0x12, 0x03,
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];
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for data_len in 0..=unmasked.len() {
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let unmasked = &unmasked[0..data_len];
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// Check masking with different alignment.
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for off in 0..=3 {
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if unmasked.len() < off {
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continue;
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}
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let mut masked = unmasked.to_vec();
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apply_mask_fallback(&mut masked[off..], mask);
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let mut masked_fast = unmasked.to_vec();
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apply_mask_fast32(&mut masked_fast[off..], mask);
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assert_eq!(masked, masked_fast);
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}
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}
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}
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}
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