Eliminate some more transmute() (#8879)

* eliminate some more transmute()

* Address `review comments`

* Make unsafe block smaller
* Use different byte-order than `std`, read words as big endian instead
of little endian!

* Fix IpAddresses nits

* Use `from_be` to work both for big and little endian
* Ipv6 addresses were incorrectly `transmuted`

* remove needless lifetime annotation

util/network-devp2p/src/ip_utils.rs

@@ -20,8 +20,8 @@ use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV
 use std::io;
 use igd::{PortMappingProtocol, search_gateway_from_timeout};
 use std::time::Duration;
-use node_table::{NodeEndpoint};
-use ipnetwork::{IpNetwork};
+use node_table::NodeEndpoint;
+use ipnetwork::IpNetwork;
 
 /// Socket address extension for rustc beta. To be replaces with now unstable API
 pub trait SocketAddrExt {
@@ -225,28 +225,17 @@ mod getinterfaces {
 				let sa: *const sockaddr_in = sa as *const sockaddr_in;
 				let sa = unsafe { &*sa };
 				let (addr, port) = (sa.sin_addr.s_addr, sa.sin_port);
-				(IpAddr::V4(Ipv4Addr::new(
-					(addr & 0x0000_00FF) as u8,
-					((addr & 0x0000_FF00) >>  8) as u8,
-					((addr & 0x00FF_0000) >> 16) as u8,
-					((addr & 0xFF00_0000) >> 24) as u8)),
-					port)
+				// convert u32 to an `Ipv4 address`, but the u32 must be converted to `host-order`
+				// that's why `from_be` is used!
+				(IpAddr::V4(Ipv4Addr::from(<u32>::from_be(addr))), port)
 			},
 			AF_INET6 => {
 				let sa: *const sockaddr_in6 = sa as *const sockaddr_in6;
 				let sa = & unsafe { *sa };
 				let (addr, port) = (sa.sin6_addr.s6_addr, sa.sin6_port);
-				let addr: [u16; 8] = unsafe { mem::transmute(addr) };
-				(IpAddr::V6(Ipv6Addr::new(
-					addr[0],
-					addr[1],
-					addr[2],
-					addr[3],
-					addr[4],
-					addr[5],
-					addr[6],
-					addr[7])),
-					port)
+				let ip_addr = Ipv6Addr::from(addr);
+				debug_assert!(addr == ip_addr.octets());
+				(IpAddr::V6(ip_addr), port)
 			},
 			_ => return None,
 		};