Misaligned pointer dereference in safe functions backend::channel and sockaddr_to_network_addr

[shinmao]

The source of unsoundness

Hi, we consider that casting from sa_family to c_int would break the alignment requirement because the first one is aligned to 2 bytes while the later one is aligned to 4 bytes. Consider following two functions:

libpnet/pnet_datalink/src/linux.rs

Line 206 in 87f362d

send_addr: unsafe { *(send_addr as *const libc::sockaddr_ll) },

libpnet/pnet_datalink/src/unix_interfaces.rs

Lines 114 to 115 in 87f362d

	} else if (*sa).sa_family as libc::c_int == libc::AF_PACKET {
	let sll: *const libc::sockaddr_ll = mem::transmute(sa);

send_addr is also aligned to the bytes of sa_family, and it could lead to undefined behavior in safe function