netstack: scheme/ip.rs to smoltcp 0.13.1 API

Three call sites needed 0.13.1 adaptation:

- hop_limit/set_hop_limit are now methods, not public
  fields. Use self.hop_limit() and self.set_hop_limit().
- RawSocket::new takes Option<IpVersion> and Option<IpProtocol>,
  not the bare enums.
- socket.ip_protocol() returns Option<IpProtocol>; print via
  Debug so both Some(known) and None render usefully.

Verified by cargo check.

netstack/src/scheme/ip.rs

@@ -53,11 +53,11 @@ impl<'a> SchemeSocket for RawSocket<'a> {
     }
 
     fn hop_limit(&self) -> u8 {
-        self.hop_limit
+        self.hop_limit()
     }
 
     fn set_hop_limit(&mut self, hop_limit: u8) {
-        self.hop_limit = hop_limit;
+        self.set_hop_limit(hop_limit);
     }
 
     fn new_socket(
@@ -82,8 +82,8 @@ impl<'a> SchemeSocket for RawSocket<'a> {
             vec![0; Router::MTU * Smolnetd::SOCKET_BUFFER_SIZE],
         );
         let ip_socket = RawSocket::new(
-            IpVersion::Ipv4,
-            IpProtocol::from(proto),
+            Some(IpVersion::Ipv4),
+            Some(IpProtocol::from(proto)),
             rx_buffer,
             tx_buffer,
         );
@@ -141,7 +141,7 @@ impl<'a> SchemeSocket for RawSocket<'a> {
 
     fn fpath(&self, _file: &SchemeFile<Self>, buf: &mut [u8]) -> SyscallResult<usize> {
         FpathWriter::with(buf, "ip", |w| {
-            write!(w, "{}", self.ip_protocol()).expect("write ip protocol to fpath");
+            write!(w, "{:?}", self.ip_protocol()).expect("write ip protocol to fpath");
             Ok(())
         })
     }