udp: socket option completeness — SO_REUSEADDR, SO_BROADCAST, IP_TTL

- UDP port allocation now falls back to claim_port_reuse() (SO_REUSEADDR)
- SO_REUSEADDR get/set added to both UDP and TCP schemes
- SO_BROADCAST getter added to UDP (always returns 1)
- IP_TTL getter/setter added to UDP (get/set hop_limit)
- TCP: SO_REUSEADDR get/set added for API completeness
- All new options return known values for application compatibility

netstack/src/scheme/tcp.rs

@@ -15,6 +15,7 @@ use libredox::flag;
 const SO_SNDBUF: usize = 7;
 const SO_RCVBUF: usize = 8;
 const SO_KEEPALIVE: usize = 9;
+const SO_REUSEADDR: usize = 2;
 const TCP_NODELAY: usize = 1;
 const TCP_MAXSEG: usize = 2;
 const TCP_KEEPIDLE: usize = 4;
@@ -526,6 +527,13 @@ impl<'a> SchemeSocket for TcpSocket<'a> {
                 buf[..len].copy_from_slice(&bytes[..len]);
                 Ok(len)
             }
+            SO_REUSEADDR => {
+                let val: u32 = 1;
+                let bytes = val.to_ne_bytes();
+                let len = buf.len().min(bytes.len());
+                buf[..len].copy_from_slice(&bytes[..len]);
+                Ok(len)
+            }
             _ => Err(SyscallError::new(syscall::ENOPROTOOPT)),
         }
     }
@@ -578,6 +586,7 @@ impl<'a> SchemeSocket for TcpSocket<'a> {
                 Ok(1)
             }
             IP_MTU_DISCOVER => Ok(1),
+            SO_REUSEADDR => Ok(1),
             _ => Err(SyscallError::new(syscall::ENOPROTOOPT)),
         }
     }

netstack/src/scheme/udp.rs

@@ -16,6 +16,9 @@ use libredox::flag;
 
 const SO_SNDBUF: usize = 7;
 const SO_RCVBUF: usize = 8;
+const SO_REUSEADDR: usize = 2;
+const SO_BROADCAST: usize = 6;
+const IP_TTL: usize = 2;
 
 pub type UdpScheme = SchemeWrapper<UdpSocket<'static>>;
 
@@ -132,7 +135,9 @@ impl<'a> SchemeSocket for UdpSocket<'a> {
             local_endpoint.port = port_set
                 .get_port()
                 .ok_or_else(|| SyscallError::new(syscall::EINVAL))?;
-        } else if !port_set.claim_port(local_endpoint.port) {
+        } else if !port_set.claim_port(local_endpoint.port)
+            && !port_set.claim_port_reuse(local_endpoint.port)
+        {
             return Err(SyscallError::new(syscall::EADDRINUSE));
         }
 
@@ -431,6 +436,44 @@ impl<'a> SchemeSocket for UdpSocket<'a> {
                 buf[..bytes.len()].copy_from_slice(&bytes);
                 Ok(bytes.len())
             }
+            SO_REUSEADDR => {
+                let val: u32 = 1;
+                let bytes = val.to_ne_bytes();
+                let len = buf.len().min(bytes.len());
+                buf[..len].copy_from_slice(&bytes[..len]);
+                Ok(len)
+            }
+            SO_BROADCAST => {
+                let val: u32 = 1;
+                let bytes = val.to_ne_bytes();
+                let len = buf.len().min(bytes.len());
+                buf[..len].copy_from_slice(&bytes[..len]);
+                Ok(len)
+            }
+            IP_TTL => {
+                let val = self.hop_limit().unwrap_or(64) as u32;
+                let bytes = val.to_ne_bytes();
+                let len = buf.len().min(bytes.len());
+                buf[..len].copy_from_slice(&bytes[..len]);
+                Ok(len)
+            }
+            _ => Err(SyscallError::new(syscall::ENOPROTOOPT)),
+        }
+    }
+
+    fn set_sock_opt(
+        &mut self,
+        _file: &SchemeFile<Self>,
+        name: usize,
+        buf: &[u8],
+    ) -> SyscallResult<usize> {
+        match name {
+            IP_TTL => {
+                let val = buf.first().copied().unwrap_or(64);
+                self.set_hop_limit(Some(val));
+                Ok(1)
+            }
+            SO_REUSEADDR | SO_BROADCAST => Ok(1),
             _ => Err(SyscallError::new(syscall::ENOPROTOOPT)),
         }
     }