exploratory code for supporting icmp extensions

Cargo.toml

@@ -74,6 +74,7 @@ windows-sys = { version = "0.48.0", features = [
 ] }
 
 [dev-dependencies]
+hex-literal = "0.4.1"
 rand = "0.8.5"
 test-case = "3.2.1"
 

src/tracing/net/channel.rs

@@ -180,7 +180,11 @@ impl TracerChannel {
     fn recv_icmp_probe(&mut self) -> TraceResult<Option<ProbeResponse>> {
         if self.recv_socket.is_readable(self.read_timeout)? {
             match self.dest_addr {
-                IpAddr::V4(_) => ipv4::recv_icmp_probe(&mut self.recv_socket, self.protocol),
+                IpAddr::V4(_) => ipv4::recv_icmp_probe(
+                    &mut self.recv_socket,
+                    self.protocol,
+                    self.ipv4_length_order,
+                ),
                 IpAddr::V6(_) => ipv6::recv_icmp_probe(&mut self.recv_socket, self.protocol),
             }
         } else {

src/tracing/net/ipv4.rs

@@ -8,12 +8,14 @@ use crate::tracing::packet::checksum::{icmp_ipv4_checksum, udp_ipv4_checksum};
 use crate::tracing::packet::icmpv4::destination_unreachable::DestinationUnreachablePacket;
 use crate::tracing::packet::icmpv4::echo_reply::EchoReplyPacket;
 use crate::tracing::packet::icmpv4::echo_request::EchoRequestPacket;
+use crate::tracing::packet::icmpv4::extension::extension_header::ExtensionHeader;
+use crate::tracing::packet::icmpv4::extension::extension_structure::ExtensionStructure;
 use crate::tracing::packet::icmpv4::time_exceeded::TimeExceededPacket;
 use crate::tracing::packet::icmpv4::{IcmpCode, IcmpPacket, IcmpType};
 use crate::tracing::packet::ipv4::Ipv4Packet;
 use crate::tracing::packet::tcp::TcpPacket;
 use crate::tracing::packet::udp::UdpPacket;
-use crate::tracing::packet::IpProtocol;
+use crate::tracing::packet::{fmt_payload, IpProtocol};
 use crate::tracing::probe::{
     ProbeResponse, ProbeResponseData, ProbeResponseSeq, ProbeResponseSeqIcmp, ProbeResponseSeqTcp,
     ProbeResponseSeqUdp,
@@ -187,12 +189,13 @@ pub fn dispatch_tcp_probe(
 pub fn recv_icmp_probe(
     recv_socket: &mut Socket,
     protocol: TracerProtocol,
+    ipv4_byte_order: platform::PlatformIpv4FieldByteOrder,
 ) -> TraceResult<Option<ProbeResponse>> {
     let mut buf = [0_u8; MAX_PACKET_SIZE];
     match recv_socket.read(&mut buf) {
         Ok(_bytes_read) => {
             let ipv4 = Ipv4Packet::new_view(&buf).req()?;
-            Ok(extract_probe_resp(protocol, &ipv4)?)
+            Ok(extract_probe_resp(protocol, ipv4_byte_order, &ipv4)?)
         }
         Err(err) => match err.kind() {
             ErrorKind::WouldBlock => Ok(None),
@@ -324,22 +327,73 @@ fn udp_payload_size(packet_size: usize) -> usize {
 #[instrument]
 fn extract_probe_resp(
     protocol: TracerProtocol,
+    ipv4_byte_order: platform::PlatformIpv4FieldByteOrder,
     ipv4: &Ipv4Packet<'_>,
 ) -> TraceResult<Option<ProbeResponse>> {
     let recv = SystemTime::now();
     let src = IpAddr::V4(ipv4.get_source());
-    let icmp_v4 = IcmpPacket::new_view(ipv4.payload()).req()?;
+
+    // if ipv4.get_source() == Ipv4Addr::new(129, 250,2, 50) {
+    //     println!("found");
+    // }
+
+    // should this include the IP header?  Seems it does not
+    //
+    // wireshark:   45 20 00 38
+    // We get:      45 20 24 00
+    //
+    // we convert 24 00 to be 00 24 which is 36
+    // we then subtract 20 the Ipv4 header (20) and get 16
+    //
+    // we set set_header_included(true) on the ipv4 recv socket, so I guess macOS subtracts it already?
+    // TODO how does this behave on other platforms?
+
+    let total_length = ipv4_byte_order.adjust_length(ipv4.get_total_length());
+    // let header_length = ipv4.get_header_length() as usize * 4;
+    // let payload_length = total_length as usize; //.saturating_sub(header_length);
+    let ipv4_payload = &ipv4.payload_new()[..total_length as usize];
+
+    let icmp_v4 = IcmpPacket::new_view(ipv4_payload).req()?;
+
     Ok(match icmp_v4.get_icmp_type() {
         IcmpType::TimeExceeded => {
             let packet = TimeExceededPacket::new_view(icmp_v4.packet()).req()?;
-            let resp_seq = extract_probe_resp_seq(packet.payload(), protocol)?;
+            let payload = packet.payload();
+            let extension = packet.extension();
+            if let Some(ext) = extension {
+                let extensions = ExtensionStructure::new_view(ext).req()?;
+                let ext_header = ExtensionHeader::new_view(extensions.header()).req()?;
+                println!(
+                    "extension header: version={}, checksum={}",
+                    ext_header.get_version(),
+                    ext_header.get_checksum()
+                );
+                for obj in extensions.iter() {
+                    println!("extension object: length={:?}, class_num={:?}, class_subtype={:?}, payload={}", obj.get_length(), obj.get_class_num(), obj.get_class_subtype(), fmt_payload(obj.payload()));
+                }
+            }
+            let resp_seq = extract_probe_resp_seq(payload, protocol)?;
             Some(ProbeResponse::TimeExceeded(ProbeResponseData::new(
                 recv, src, resp_seq,
             )))
         }
         IcmpType::DestinationUnreachable => {
             let packet = DestinationUnreachablePacket::new_view(icmp_v4.packet()).req()?;
-            let resp_seq = extract_probe_resp_seq(packet.payload(), protocol)?;
+            let payload = packet.payload();
+            let extension = packet.extension();
+            if let Some(ext) = extension {
+                let extensions = ExtensionStructure::new_view(ext).req()?;
+                let ext_header = ExtensionHeader::new_view(extensions.header()).req()?;
+                println!(
+                    "extension header: version={}, checksum={}",
+                    ext_header.get_version(),
+                    ext_header.get_checksum()
+                );
+                for obj in extensions.iter() {
+                    println!("extension object: length={:?}, class_num={:?}, class_subtype={:?}, payload={}", obj.get_length(), obj.get_class_num(), obj.get_class_subtype(), fmt_payload(obj.payload()));
+                }
+            }
+            let resp_seq = extract_probe_resp_seq(payload, protocol)?;
             Some(ProbeResponse::DestinationUnreachable(
                 ProbeResponseData::new(recv, src, resp_seq),
             ))

src/tracing/packet.rs

@@ -21,7 +21,7 @@ pub mod udp;
 /// `TCP` packets.
 pub mod tcp;
 
-fn fmt_payload(bytes: &[u8]) -> String {
+pub fn fmt_payload(bytes: &[u8]) -> String {
     use itertools::Itertools as _;
     format!("{:02x}", bytes.iter().format(" "))
 }