feat: add support for DSCP and TTL / Hop Limit

Cargo.toml

@@ -28,7 +28,7 @@ targets = [
 ]
 
 [dependencies]
-libc = { version = "0.2.155", features = ["extra_traits"] }
+libc = { git = "https://github.com/rust-lang/libc", branch = "libc-0.2", features = ["extra_traits"] }
 bitflags = "2.3.3"
 cfg-if = "1.0"
 pin-utils = { version = "0.1.0", optional = true }

changelog/2425.added.md

@@ -0,0 +1,2 @@
+Improve support for extracting the TTL / Hop Limit from incoming packets
+and support for DSCP (ToS / Traffic Class).

src/sys/socket/mod.rs

@@ -769,6 +769,43 @@ pub enum ControlMessageOwned {
     #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
     Ipv6OrigDstAddr(libc::sockaddr_in6),
 
+    /// Time-to-Live (TTL) header field of the incoming IPv4 packet.
+    ///
+    /// [Further reading](https://www.man7.org/linux/man-pages/man7/ip.7.html)
+    #[cfg(linux_android)]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv4Ttl(i32),
+
+    /// Time-to-Live (TTL) header field of the incoming IPv4 packet.
+    ///
+    /// [Further reading](https://datatracker.ietf.org/doc/html/rfc3542.html)
+    #[cfg(target_os = "freebsd")]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv4Ttl(u8),
+
+    /// Hop Limit header field of the incoming IPv6 packet.
+    ///
+    /// [Further reading for Linux](https://www.man7.org/linux/man-pages/man7/ip.7.html)
+    /// [Further reading for FreeBSD](https://datatracker.ietf.org/doc/html/rfc3542.html)
+    #[cfg(any(linux_android, target_os = "freebsd"))]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv6HopLimit(i32),
+
+    /// Retrieve the DSCP (ToS) header field of the incoming IPv4 packet. 
+    #[cfg(any(linux_android, target_os = "freebsd"))]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv4Tos(u8),
+
+    /// Retrieve the DSCP (Traffic Class) header field of the incoming IPv6 packet. 
+    #[cfg(any(linux_android, target_os = "freebsd"))]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv6TClass(i32), 
+
     /// UDP Generic Receive Offload (GRO) allows receiving multiple UDP
     /// packets from a single sender.
     /// Fixed-size payloads are following one by one in a receive buffer.
@@ -987,6 +1024,42 @@ impl ControlMessageOwned {
                 let content_type = unsafe { ptr::read_unaligned(p as *const u8) };
                 ControlMessageOwned::TlsGetRecordType(content_type.into())
             },
+            #[cfg(linux_android)]
+            #[cfg(feature = "net")]
+            (libc::IPPROTO_IP, libc::IP_TTL) => {
+                let ttl = unsafe { ptr::read_unaligned(p as *const i32) };
+                ControlMessageOwned::Ipv4Ttl(ttl)
+            },
+            #[cfg(target_os = "freebsd")]
+            #[cfg(feature = "net")]
+            (libc::IPPROTO_IP, libc::IP_RECVTTL) => {
+                let ttl: u8 = unsafe { ptr::read_unaligned(p as *const u8) };
+                ControlMessageOwned::Ipv4Ttl(ttl)
+            },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            (libc::IPPROTO_IPV6, libc::IPV6_HOPLIMIT) => {
+                let ttl = unsafe { ptr::read_unaligned(p as *const i32) };
+                ControlMessageOwned::Ipv6HopLimit(ttl)
+            },
+            #[cfg(linux_android)]
+            #[cfg(feature = "net")]
+            (libc::IPPROTO_IP, libc::IP_TOS) => {
+                let tos = unsafe { ptr::read_unaligned(p as *const u8) };
+                ControlMessageOwned::Ipv4Tos(tos)
+            },
+            #[cfg(target_os = "freebsd")]
+            #[cfg(feature = "net")]
+            (libc::IPPROTO_IP, libc::IP_RECVTOS) => {
+                let tos = unsafe { ptr::read_unaligned(p as *const u8) };
+                ControlMessageOwned::Ipv4Tos(tos)
+            },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            (libc::IPPROTO_IPV6, libc::IPV6_TCLASS) => {
+                let tc = unsafe { ptr::read_unaligned(p as *const i32) };
+                ControlMessageOwned::Ipv6TClass(tc)
+            },
             (_, _) => {
                 let sl = unsafe { std::slice::from_raw_parts(p, len) };
                 let ucmsg = UnknownCmsg(*header, Vec::<u8>::from(sl));
@@ -1124,6 +1197,18 @@ pub enum ControlMessage<'a> {
     #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
     Ipv4SendSrcAddr(&'a libc::in_addr),
 
+    /// Configure the Time-to-Live for v4 traffic.
+    #[cfg(linux_android)]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv4Ttl(&'a libc::c_int),
+
+    /// Configure the Time-to-Live for v4 traffic.
+    #[cfg(target_os = "freebsd")]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv4Ttl(&'a libc::c_uchar),
+
     /// Configure the hop limit for v6 multicast traffic.
     ///
     /// Set the IPv6 hop limit for this message. The argument is an integer
@@ -1138,9 +1223,9 @@ pub enum ControlMessage<'a> {
     Ipv6HopLimit(&'a libc::c_int),
 
     /// SO_RXQ_OVFL indicates that an unsigned 32 bit value
-    /// ancilliary msg (cmsg) should be attached to recieved
+    /// ancillary msg (cmsg) should be attached to received
     /// skbs indicating the number of packets dropped by the
-    /// socket between the last recieved packet and this
+    /// socket between the last received packet and this
     /// received packet.
     #[cfg(any(linux_android, target_os = "fuchsia"))]
     RxqOvfl(&'a u32),
@@ -1152,6 +1237,22 @@ pub enum ControlMessage<'a> {
     /// page.
     #[cfg(target_os = "linux")]
     TxTime(&'a u64),
+
+    /// Configure DSCP / IP TOS for outgoing v4 packets.
+    ///
+    /// Further information can be found [here](https://en.wikipedia.org/wiki/Differentiated_services).
+    #[cfg(any(linux_android, target_os = "freebsd"))]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv4Tos(&'a u8),
+
+    /// Configure DSCP / IPv6 TCLASS for outgoing v6 packets.
+    ///
+    /// Further information can be found [here](https://en.wikipedia.org/wiki/Differentiated_services).
+    #[cfg(any(linux_android, target_os = "freebsd"))]
+    #[cfg(feature = "net")]
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    Ipv6TClass(&'a i32),
 }
 
 // An opaque structure used to prevent cmsghdr from being a public type
@@ -1245,6 +1346,9 @@ impl<'a> ControlMessage<'a> {
             #[cfg(any(freebsdlike, netbsdlike))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv4SendSrcAddr(addr) => addr as *const _ as *const u8,
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Ttl(ttl) => ttl as *const _ as *const u8,
             #[cfg(any(linux_android, freebsdlike, apple_targets, target_os = "haiku"))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv6HopLimit(limit) => limit as *const _ as *const u8,
@@ -1256,6 +1360,16 @@ impl<'a> ControlMessage<'a> {
             ControlMessage::TxTime(tx_time) => {
                 tx_time as *const _ as *const u8
             },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Tos(tos) => {
+                tos as *const _
+            },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv6TClass(tclass) => {
+                tclass as *const _ as *const u8
+            },
         };
         unsafe {
             ptr::copy_nonoverlapping(
@@ -1307,6 +1421,11 @@ impl<'a> ControlMessage<'a> {
             #[cfg(any(freebsdlike, netbsdlike))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv4SendSrcAddr(addr) => mem::size_of_val(addr),
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Ttl(ttl) => {
+                mem::size_of_val(ttl)
+            },
             #[cfg(any(linux_android, freebsdlike, apple_targets, target_os = "haiku"))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv6HopLimit(limit) => {
@@ -1320,6 +1439,16 @@ impl<'a> ControlMessage<'a> {
             ControlMessage::TxTime(tx_time) => {
                 mem::size_of_val(tx_time)
             },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Tos(tos) => {
+                mem::size_of_val(tos)
+            },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv6TClass(tclass) => {
+                mem::size_of_val(tclass)
+            },
         }
     }
 
@@ -1347,13 +1476,22 @@ impl<'a> ControlMessage<'a> {
             #[cfg(any(freebsdlike, netbsdlike))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv4SendSrcAddr(_) => libc::IPPROTO_IP,
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Ttl(_) => libc::IPPROTO_IP,
             #[cfg(any(linux_android, freebsdlike, apple_targets, target_os = "haiku"))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv6HopLimit(_) => libc::IPPROTO_IPV6,
             #[cfg(any(linux_android, target_os = "fuchsia"))]
             ControlMessage::RxqOvfl(_) => libc::SOL_SOCKET,
             #[cfg(target_os = "linux")]
             ControlMessage::TxTime(_) => libc::SOL_SOCKET,
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Tos(_) => libc::IPPROTO_IP,
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv6TClass(_) => libc::IPPROTO_IPV6,
         }
     }
 
@@ -1392,6 +1530,9 @@ impl<'a> ControlMessage<'a> {
             #[cfg(any(freebsdlike, netbsdlike))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv4SendSrcAddr(_) => libc::IP_SENDSRCADDR,
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Ttl(_) => libc::IP_TTL,
             #[cfg(any(linux_android, freebsdlike, apple_targets, target_os = "haiku"))]
             #[cfg(feature = "net")]
             ControlMessage::Ipv6HopLimit(_) => libc::IPV6_HOPLIMIT,
@@ -1403,6 +1544,16 @@ impl<'a> ControlMessage<'a> {
             ControlMessage::TxTime(_) => {
                 libc::SCM_TXTIME
             },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv4Tos(_) => {
+                libc::IP_TOS
+            },
+            #[cfg(any(linux_android, target_os = "freebsd"))]
+            #[cfg(feature = "net")]
+            ControlMessage::Ipv6TClass(_) => {
+                libc::IPV6_TCLASS
+            },
         }
     }
 

src/sys/socket/sockopt.rs

@@ -402,29 +402,51 @@ sockopt_impl!(
     libc::SO_PRIORITY,
     libc::c_int
 );
-#[cfg(target_os = "linux")]
+#[cfg(any(linux_android, target_os = "freebsd"))]
 #[cfg(feature = "net")]
 sockopt_impl!(
     #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
     /// Set or receive the Type-Of-Service (TOS) field that is
     /// sent with every IP packet originating from this socket
-    IpTos,
+    Ipv4Tos,
     Both,
     libc::IPPROTO_IP,
     libc::IP_TOS,
     libc::c_int
 );
-#[cfg(target_os = "linux")]
+#[cfg(any(linux_android, target_os = "freebsd"))]
 #[cfg(feature = "net")]
 sockopt_impl!(
     #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
-    /// Traffic class associated with outgoing packets
+    /// If enabled, the IP_TOS ancillary message is passed with incoming packets.
+    IpRecvTos,
+    Both,
+    libc::IPPROTO_IP,
+    libc::IP_RECVTOS,
+    bool
+);
+#[cfg(any(linux_android, target_os = "freebsd"))]
+#[cfg(feature = "net")]
+sockopt_impl!(
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    /// Set the traffic class associated with outgoing packets.
     Ipv6TClass,
     Both,
     libc::IPPROTO_IPV6,
     libc::IPV6_TCLASS,
     libc::c_int
 );
+#[cfg(any(linux_android, target_os = "freebsd"))]
+#[cfg(feature = "net")]
+sockopt_impl!(
+    #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
+    /// If enabled, the IPV6_TCLASS ancillary message is passed with incoming packets.
+    Ipv6RecvTClass,
+    Both,
+    libc::IPPROTO_IPV6,
+    libc::IPV6_RECVTCLASS,
+    bool
+);
 #[cfg(any(linux_android, target_os = "fuchsia"))]
 #[cfg(feature = "net")]
 sockopt_impl!(
@@ -1058,6 +1080,17 @@ sockopt_impl!(
     libc::IP_TTL,
     libc::c_int
 );
+#[cfg(any(linux_android, target_os = "freebsd"))]
+#[cfg(feature = "net")]
+sockopt_impl!(
+    /// Enables a receiving socket to retrieve the Time-to-Live (TTL) field 
+    /// from incoming IPv4 packets.
+    Ipv4RecvTtl,
+    Both,
+    libc::IPPROTO_IP,
+    libc::IP_RECVTTL,
+    bool
+);
 #[cfg(any(apple_targets, linux_android, target_os = "freebsd"))]
 sockopt_impl!(
     /// Set the unicast hop limit for the socket.
@@ -1069,6 +1102,17 @@ sockopt_impl!(
 );
 #[cfg(any(linux_android, target_os = "freebsd"))]
 #[cfg(feature = "net")]
+sockopt_impl!(
+    /// Enables a receiving socket to retrieve the Hop Limit field 
+    /// (similar to TTL in IPv4) from incoming IPv6 packets.
+    Ipv6RecvHopLimit,
+    Both,
+    libc::IPPROTO_IPV6,
+    libc::IPV6_RECVHOPLIMIT,
+    bool
+);
+#[cfg(any(linux_android, target_os = "freebsd"))]
+#[cfg(feature = "net")]
 sockopt_impl!(
     #[cfg_attr(docsrs, doc(cfg(feature = "net")))]
     /// The `recvmsg(2)` call will return the destination IP address for a UDP