The os_socketaddr crate has assumed std::net::SocketAddrV4 and std::net::SocketAddrV6 have the same memory layout as the system C representation sockaddr. It has simply casted the pointers to convert the socket addresses to the system representation.
These layout were changed into idiomatic rust types in nightly std. Starting from rustc 1.64 the affected versions of this crate will have undefined behaviour.