Add support for most DCCP socket options

Not all socket options are added. Most notably DCCP_SOCKOPT_QPOLICY_ID
could not be added since some constants needed for it aren't available
in the libc crate. Namely  DCCPQ_POLICY_SIMPLE, DCCPQ_POLICY_PRIO and
DCCP_SCM_PRIORITY.

Co-authored-by: Thomas de Zeeuw <thomasdezeeuw@gmail.com>

src/lib.rs

@@ -257,6 +257,13 @@ impl Type {
     /// Used for protocols such as UDP.
     pub const DGRAM: Type = Type(sys::SOCK_DGRAM);
 
+    /// Type corresponding to `SOCK_DCCP`.
+    ///
+    /// Used for the DCCP protocol.
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub const DCCP: Type = Type(sys::SOCK_DCCP);
+
     /// Type corresponding to `SOCK_SEQPACKET`.
     #[cfg(feature = "all")]
     #[cfg_attr(docsrs, doc(cfg(feature = "all")))]
@@ -307,6 +314,11 @@ impl Protocol {
     /// Protocol corresponding to `MPTCP`.
     pub const MPTCP: Protocol = Protocol(sys::IPPROTO_MPTCP);
 
+    /// Protocol corresponding to `DCCP`.
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub const DCCP: Protocol = Protocol(sys::IPPROTO_DCCP);
+
     #[cfg(all(feature = "all", any(target_os = "freebsd", target_os = "linux")))]
     /// Protocol corresponding to `SCTP`.
     pub const SCTP: Protocol = Protocol(sys::IPPROTO_SCTP);

src/sys/unix.rs

@@ -57,12 +57,16 @@ pub(crate) use libc::c_int;
 // Used in `Domain`.
 pub(crate) use libc::{AF_INET, AF_INET6, AF_UNIX};
 // Used in `Type`.
+#[cfg(all(feature = "all", target_os = "linux"))]
+pub(crate) use libc::SOCK_DCCP;
 #[cfg(all(feature = "all", not(target_os = "redox")))]
 pub(crate) use libc::SOCK_RAW;
 #[cfg(feature = "all")]
 pub(crate) use libc::SOCK_SEQPACKET;
 pub(crate) use libc::{SOCK_DGRAM, SOCK_STREAM};
 // Used in `Protocol`.
+#[cfg(all(feature = "all", target_os = "linux"))]
+pub(crate) use libc::IPPROTO_DCCP;
 #[cfg(target_os = "linux")]
 pub(crate) use libc::IPPROTO_MPTCP;
 #[cfg(all(feature = "all", any(target_os = "freebsd", target_os = "linux")))]
@@ -382,6 +386,8 @@ impl_debug!(
     Type,
     libc::SOCK_STREAM,
     libc::SOCK_DGRAM,
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    libc::SOCK_DCCP,
     #[cfg(not(target_os = "redox"))]
     libc::SOCK_RAW,
     #[cfg(not(any(target_os = "redox", target_os = "haiku")))]
@@ -419,6 +425,8 @@ impl_debug!(
     libc::IPPROTO_UDP,
     #[cfg(target_os = "linux")]
     libc::IPPROTO_MPTCP,
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    libc::IPPROTO_DCCP,
     #[cfg(all(feature = "all", any(target_os = "freebsd", target_os = "linux")))]
     libc::IPPROTO_SCTP,
 );
@@ -2213,6 +2221,258 @@ impl crate::Socket {
         ))
         .map(|_| ())
     }
+
+    /// Set value for the `DCCP_SOCKOPT_SERVICE` option on this socket.
+    ///
+    /// Sets the DCCP service. The specification mandates use of service codes.
+    /// If this socket option is not set, the socket will fall back to 0 (which
+    /// means that no meaningful service code is present). On active sockets
+    /// this is set before [`connect`]. On passive sockets up to 32 service
+    /// codes can be set before calling [`bind`]
+    ///
+    /// [`connect`]: crate::Socket::connect
+    /// [`bind`]: crate::Socket::bind
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn set_dccp_service(&self, code: u32) -> io::Result<()> {
+        unsafe {
+            setsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_SERVICE,
+                code,
+            )
+        }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_SERVICE` option on this socket.
+    ///
+    /// For more information about this option see [`set_dccp_service`]
+    ///
+    /// [`set_dccp_service`]: crate::Socket::set_dccp_service
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_service(&self) -> io::Result<u32> {
+        unsafe { getsockopt(self.as_raw(), libc::SOL_DCCP, libc::DCCP_SOCKOPT_SERVICE) }
+    }
+
+    /// Set value for the `DCCP_SOCKOPT_CCID` option on this socket.
+    ///
+    /// This option sets both the TX and RX CCIDs at the same time.
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn set_dccp_ccid(&self, ccid: u8) -> io::Result<()> {
+        unsafe { setsockopt(self.as_raw(), libc::SOL_DCCP, libc::DCCP_SOCKOPT_CCID, ccid) }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_TX_CCID` option on this socket.
+    ///
+    /// For more information about this option see [`set_dccp_ccid`].
+    ///
+    /// [`set_dccp_ccid`]: crate::Socket::set_dccp_ccid
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_tx_ccid(&self) -> io::Result<u32> {
+        unsafe { getsockopt(self.as_raw(), libc::SOL_DCCP, libc::DCCP_SOCKOPT_TX_CCID) }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_RX_CCID` option on this socket.
+    ///
+    /// For more information about this option see [`set_dccp_ccid`].
+    ///
+    /// [`set_dccp_ccid`]: crate::Socket::set_dccp_ccid
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_xx_ccid(&self) -> io::Result<u32> {
+        unsafe { getsockopt(self.as_raw(), libc::SOL_DCCP, libc::DCCP_SOCKOPT_RX_CCID) }
+    }
+
+    /// Set value for the `DCCP_SOCKOPT_SERVER_TIMEWAIT` option on this socket.
+    ///
+    /// Enables a listening socket to hold timewait state when closing the
+    /// connection. This option must be set after `accept` returns.
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn set_dccp_server_timewait(&self, hold_timewait: bool) -> io::Result<()> {
+        unsafe {
+            setsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_SERVER_TIMEWAIT,
+                hold_timewait as c_int,
+            )
+        }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_SERVER_TIMEWAIT` option on this socket.
+    ///
+    /// For more information see [`set_dccp_server_timewait`]
+    ///
+    /// [`set_dccp_server_timewait`]: crate::Socket::set_dccp_server_timewait
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_server_timewait(&self) -> io::Result<bool> {
+        unsafe {
+            getsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_SERVER_TIMEWAIT,
+            )
+        }
+    }
+
+    /// Set value for the `DCCP_SOCKOPT_SEND_CSCOV` option on this socket.
+    ///
+    /// Both this option and `DCCP_SOCKOPT_RECV_CSCOV` are used for setting the
+    /// partial checksum coverage. The default is that checksums always cover
+    /// the entire packet and that only fully covered application data is
+    /// accepted by the receiver. Hence, when using this feature on the sender,
+    /// it must be enabled at the receiver too, with suitable choice of CsCov.
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn set_dccp_send_cscov(&self, level: u32) -> io::Result<()> {
+        unsafe {
+            setsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_SEND_CSCOV,
+                level,
+            )
+        }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_SEND_CSCOV` option on this socket.
+    ///
+    /// For more information on this option see [`set_dccp_send_cscov`].
+    ///
+    /// [`set_dccp_send_cscov`]: crate::Socket::set_dccp_send_cscov
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_send_cscov(&self) -> io::Result<u32> {
+        unsafe { getsockopt(self.as_raw(), libc::SOL_DCCP, libc::DCCP_SOCKOPT_SEND_CSCOV) }
+    }
+
+    /// Set the value of the `DCCP_SOCKOPT_RECV_CSCOV` option on this socket.
+    ///
+    /// This option is only useful when combined with [`set_dccp_send_cscov`].
+    ///
+    /// [`set_dccp_send_cscov`]: crate::Socket::set_dccp_send_cscov
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn set_dccp_recv_cscov(&self, level: u32) -> io::Result<()> {
+        unsafe {
+            setsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_RECV_CSCOV,
+                level,
+            )
+        }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_RECV_CSCOV` option on this socket.
+    ///
+    /// For more information on this option see [`set_dccp_recv_cscov`].
+    ///
+    /// [`set_dccp_recv_cscov`]: crate::Socket::set_dccp_recv_cscov
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_recv_cscov(&self) -> io::Result<u32> {
+        unsafe { getsockopt(self.as_raw(), libc::SOL_DCCP, libc::DCCP_SOCKOPT_RECV_CSCOV) }
+    }
+
+    /// Set value for the `DCCP_SOCKOPT_QPOLICY_TXQLEN` option on this socket.
+    ///
+    /// This option sets the maximum length of the output queue. A zero value is
+    /// interpreted as unbounded queue length.
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn set_dccp_qpolicy_txqlen(&self, length: u32) -> io::Result<()> {
+        unsafe {
+            setsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_QPOLICY_TXQLEN,
+                length,
+            )
+        }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_QPOLICY_TXQLEN` on this socket.
+    ///
+    /// For more information on this option see [`set_dccp_qpolicy_txqlen`].
+    ///
+    /// [`set_dccp_qpolicy_txqlen`]: crate::Socket::set_dccp_qpolicy_txqlen
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_qpolicy_txqlen(&self) -> io::Result<u32> {
+        unsafe {
+            getsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_QPOLICY_TXQLEN,
+            )
+        }
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_AVAILABLE_CCIDS` option on this socket.
+    ///
+    /// Returns the list of CCIDs supported by the endpoint.
+    ///
+    /// The parameter `N` is used to get the maximum number of supported
+    /// endpoints. The [documentation] recommends a minimum of four at the time
+    /// of writing.
+    ///
+    /// [documentation]: https://www.kernel.org/doc/html/latest/networking/dccp.html
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_available_ccids<const N: usize>(&self) -> io::Result<CcidEndpoints<N>> {
+        let mut endpoints = [0; N];
+        let mut length = endpoints.len() as libc::socklen_t;
+        syscall!(getsockopt(
+            self.as_raw(),
+            libc::SOL_DCCP,
+            libc::DCCP_SOCKOPT_AVAILABLE_CCIDS,
+            endpoints.as_mut_ptr().cast(),
+            &mut length,
+        ))?;
+        Ok(CcidEndpoints { endpoints, length })
+    }
+
+    /// Get the value of the `DCCP_SOCKOPT_GET_CUR_MPS` option on this socket.
+    ///
+    /// This option retrieves the current maximum packet size (application
+    /// payload size) in bytes.
+    #[cfg(all(feature = "all", target_os = "linux"))]
+    #[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+    pub fn dccp_cur_mps(&self) -> io::Result<u32> {
+        unsafe {
+            getsockopt(
+                self.as_raw(),
+                libc::SOL_DCCP,
+                libc::DCCP_SOCKOPT_GET_CUR_MPS,
+            )
+        }
+    }
+}
+
+/// See [`Socket::dccp_available_ccids`].
+#[cfg(all(feature = "all", target_os = "linux"))]
+#[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+#[derive(Debug)]
+pub struct CcidEndpoints<const N: usize> {
+    endpoints: [u8; N],
+    length: u32,
+}
+
+#[cfg(all(feature = "all", target_os = "linux"))]
+#[cfg_attr(docsrs, doc(cfg(feature = "all", target_os = "linux")))]
+impl<const N: usize> std::ops::Deref for CcidEndpoints<N> {
+    type Target = [u8];
+
+    fn deref(&self) -> &[u8] {
+        &self.endpoints[0..self.length as usize]
+    }
 }
 
 #[cfg_attr(docsrs, doc(cfg(unix)))]

tests/socket.rs

@@ -108,6 +108,8 @@ fn protocol_fmt_debug() {
         (Protocol::UDP, "IPPROTO_UDP"),
         #[cfg(target_os = "linux")]
         (Protocol::MPTCP, "IPPROTO_MPTCP"),
+        #[cfg(all(feature = "all", target_os = "linux"))]
+        (Protocol::DCCP, "IPPROTO_DCCP"),
         #[cfg(all(feature = "all", any(target_os = "freebsd", target_os = "linux")))]
         (Protocol::SCTP, "IPPROTO_SCTP"),
         (500.into(), "500"),
@@ -1387,3 +1389,34 @@ fn tcp_congestion() {
         new_tcp_ca,
     );
 }
+
+#[test]
+#[ignore = "DCCP support is not enabled in all kernels of majors Linux distros"]
+#[cfg(all(feature = "all", target_os = "linux"))]
+fn dccp() {
+    let listener = Socket::new(Domain::IPV4, Type::DCCP, Some(Protocol::DCCP)).unwrap();
+    let addr = "127.0.0.1:0".parse::<SocketAddr>().unwrap().into();
+    listener.set_dccp_service(45).unwrap();
+    assert!(listener.dccp_service().unwrap() == 45);
+    assert!(listener.dccp_cur_mps().unwrap() > 0);
+    assert!(listener.dccp_available_ccids::<4>().unwrap().len() >= 3);
+    assert!(
+        listener.dccp_send_cscov().unwrap() == 0,
+        "sender cscov should be zero by default"
+    );
+    listener.set_dccp_ccid(2).unwrap();
+    listener.set_dccp_qpolicy_txqlen(6).unwrap();
+    assert!(listener.dccp_qpolicy_txqlen().unwrap() == 6);
+    listener.bind(&addr).unwrap();
+    listener.listen(10).unwrap();
+
+    let mut client = Socket::new(Domain::IPV4, Type::DCCP, Some(Protocol::DCCP)).unwrap();
+    client.set_dccp_service(45).unwrap();
+    client.connect(&addr).unwrap();
+
+    let (mut accepted, _) = listener.accept().unwrap();
+    let msg = "Hello World!";
+    assert!(client.write(msg.as_bytes()).unwrap() == msg.len());
+    let mut recv_buf = [0_u8; 64];
+    assert!(accepted.read(&mut recv_buf).unwrap() == msg.len());
+}