TODO in code: replace copy_nonoverlapping() with read_unaligned()

[Shnatsel]

There is a TODO in the code: "replace this with read_unaligned() as it stabilizes"

https://github.com/snapview/tungstenite-rs/blob/3abe419/src/protocol/frame/mask.rs#L31

read_unaligned() has been stabilized in Rust 1.17

Also of interest, to_bytes()/from_bytes() which seems to be the safe equivalent of what the unsafe code is doing here, is going to be stabilized in Rust 1.29, which is the next release.

[agalakhov]

Thank you!

[bluetech]

Just passing by, but I wonder why is read_unaligned needed? The &mask reference should be sufficiently aligned, according to the reference at least: https://doc.rust-lang.org/reference/type-layout.html

[agalakhov]

The &mask has an alignment of just u8, and the one of u32 is needed. It's about its contents, not the reference itself.

[bluetech]

Yes, you are correct, I misread:

An array of [T; n] has a size of size_of::<T>() * n and the same alignment of T.

Maybe it's better to just read a u32 off the wire and work with that, like actix does.

[agalakhov]

Working with u32 requires endianess-dependent code. The behaviour is defined by RFC for u8, not for u32. On an unusual CPU or in a critical environment one could disable unsafe optimizations and stick to straightforward apply_mask_fallback which is definitely correct.