Roll our own ICMPv6 Packet parser

Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "icmp"
+name = "icmp-socket"
 version = "0.1.0"
 authors = ["Jeremy Wall <jeremy@marzhillstudios.com>"]
 edition = "2018"
@@ -9,3 +9,4 @@ edition = "2018"
 [dependencies]
 socket2 = "0.3.19"
 packet = "0.1.4"
+byteorder = "1.3.4"

src/echo.rs

@@ -0,0 +1,74 @@
+// Copyright 2021 Jeremy Wall
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//     http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+use std::convert::From;
+use std::net::{Ipv4Addr, Ipv6Addr};
+
+use packet::{Builder, Packet as P};
+use packet::icmp::echo::Packet;
+
+// TODO(jwall): It turns out that the ICMPv6 packets are sufficiently
+// different from the ICMPv4 packets. In order to handle them appropriately
+// It is going to take some consideration.
+use crate::{IcmpSocket4, IcmpSocket6};
+
+pub struct EchoResponse {
+    identifier: u16,
+    sequence: u16,
+    payload: Vec<u8>,
+}
+
+pub struct EchoSocket4 {
+    sequence: u16,
+    buf: Vec<u8>,
+    inner: IcmpSocket4,
+}
+
+impl EchoSocket4 {
+    pub fn new(sock: IcmpSocket4) -> Self {
+        EchoSocket4{inner:sock, sequence: 0, buf: Vec::with_capacity(512)}
+    }
+
+    pub fn set_max_hops(&mut self, hops: u32) {
+        self.inner.set_max_hops(hops);
+    }
+
+    pub fn send_ping(&mut self, dest: Ipv4Addr, identifier: u16, payload: &[u8]) -> std::io::Result<()> {
+        let packet = packet::icmp::Builder::default()
+            .echo().unwrap().request().unwrap()
+            .identifier(identifier).unwrap()
+            .sequence(self.sequence).unwrap()
+            .payload(payload).unwrap().build().unwrap();
+        self.sequence += 1;
+        self.inner.send_to(dest, &packet)?;
+        Ok(())
+    }
+
+    pub fn recv_ping(&mut self) -> std::io::Result<EchoResponse> {
+        let bytes_read = self.inner.rcv_from(&mut self.buf)?;
+        match Packet::new(&self.buf[0..bytes_read]) {
+            Ok(p) => return Ok(EchoResponse{
+                sequence: p.sequence(),
+                identifier: p.identifier(),
+                payload: p.payload().to_owned(),
+            }),
+            Err(e) => return Err(std::io::Error::new(std::io::ErrorKind::Other, format!("Malformed ICMP Response: {:?}", e))),
+        };
+    }
+}
+
+impl From<IcmpSocket4> for EchoSocket4 {
+    fn from(sock: IcmpSocket4) -> Self {
+        EchoSocket4::new(sock)
+    }
+}

src/lib.rs

@@ -13,5 +13,8 @@
 // limitations under the License.
 
 pub mod socket;
+pub mod echo;
+pub mod packet;
 
-pub use socket::{IcmpSocket, IcmpSocket4, IcmpSocket6};
+pub use crate::packet::{Icmpv6Packet, Icmpv6Message};
+pub use socket::{IcmpSocket4, IcmpSocket6};

src/packet.rs

@@ -0,0 +1,329 @@
+// Copyright 2021 Jeremy Wall
+// 
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// 
+//     http://www.apache.org/licenses/LICENSE-2.0
+// 
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+use std::net::Ipv6Addr;
+use byteorder::{ByteOrder, BigEndian};
+
+fn ipv6_sum_words(ip: &Ipv6Addr) -> u32 {
+    ip.segments().iter().map(|x| *x as u32).sum()
+}
+
+fn sum_big_endian_words(bs: &[u8]) -> u32 {
+    if bs.len() == 0 {
+        return 0;
+    }
+
+    let len = bs.len();
+    let mut data = &bs[..];
+    let mut sum = 032;
+    // We need to stop when we have less than 2 bytes left.
+    while data.len() >= 2 {
+        sum += BigEndian::read_u16(&data[0..2]) as u32;
+        // remove the first two now that we've already summed them
+        data = &data[2..];
+    }
+
+    if len % 2 != 0 { // If odd then checksum the last byte
+        sum += (bs[len - 1] as u32) << 8;
+    }
+    return sum;
+}
+
+pub enum Icmpv6Message {
+    // NOTE(JWALL): All of the below integers should be parsed as big endian on the
+    // wire.
+    Unreachable {
+        _unused: u32,
+        invoking_packet: Vec<u8>,
+    },
+    PacketTooBig {
+        mtu: u32,
+        invoking_packet: Vec<u8>,
+    },
+    TimeExceeded {
+        _unused: u32,
+        invoking_packet: Vec<u8>,
+    },
+    ParameterProblem {
+        pointer: u32,
+        invoking_packet: Vec<u8>,
+    },
+    PrivateExperimental {
+        padding: u32,
+        payload: Vec<u8>,
+    },
+    EchoRequest {
+        identifier: u16,
+        sequence: u16,
+        payload: Vec<u8>,
+    },
+    EchoReply {
+        identifier: u16,
+        sequence: u16,
+        payload: Vec<u8>,
+    }
+}
+
+use Icmpv6Message::{Unreachable, PacketTooBig, TimeExceeded, ParameterProblem, PrivateExperimental, EchoRequest, EchoReply};
+
+impl Icmpv6Message {
+    pub fn get_bytes(&self) -> Vec<u8> {
+        let mut bytes = Vec::new();
+        match self {
+            Unreachable {_unused: field1, invoking_packet: field2 } |
+            PacketTooBig {mtu: field1, invoking_packet: field2 } |
+            TimeExceeded {_unused: field1, invoking_packet: field2 } |
+            ParameterProblem {pointer: field1, invoking_packet: field2 } |
+            PrivateExperimental {padding: field1, payload: field2 } => {
+                let mut buf = vec![0; 4];
+                BigEndian::write_u32(&mut buf, *field1);
+                bytes.append(&mut buf);
+                bytes.extend_from_slice(field2);
+            },
+            EchoRequest{
+                identifier,
+                sequence,
+                payload,
+            } | EchoReply{
+                identifier,
+                sequence,
+                payload,
+            } => {
+                let mut buf = vec![0; 2];
+                BigEndian::write_u16(&mut buf, *identifier);
+                bytes.append(&mut buf);
+                buf.resize(2, 0);
+                BigEndian::write_u16(&mut buf, *sequence);
+                bytes.append(&mut buf);
+                bytes.extend_from_slice(payload);
+            }
+        }
+        bytes
+    }
+}
+
+pub struct Icmpv6Packet {
+    // NOTE(JWALL): All of the below integers should be parsed as big endian on the
+    // wire.
+    pub typ: u8,
+    pub code: u8,
+    pub checksum: u16,
+    pub message: Icmpv6Message,
+}
+
+#[derive(Debug)]
+pub enum PacketParseError {
+    PacketTooSmall(usize),
+    UnrecognizedICMPType,
+}
+
+impl Icmpv6Packet {
+    /// Construct a packet by parsing the provided bytes.
+    pub fn parse<B: AsRef<[u8]>>(bytes: B) -> Result<Self, PacketParseError> {
+        let bytes = bytes.as_ref();
+        // NOTE(jwall): All ICMP packets are at least 8 bytes long.
+        if bytes.len() < 8 {
+            return Err(PacketParseError::PacketTooSmall(bytes.len()));
+        }
+        let (typ, code, checksum) = (bytes[0], bytes[1], BigEndian::read_u16(&bytes[2..3]));
+        let next_field = BigEndian::read_u32(&bytes[4..7]);
+        let payload = bytes[8..].to_owned();
+        let message = match typ {
+            1 => Unreachable{
+                _unused: next_field,
+                invoking_packet: payload,
+            },
+            2 => PacketTooBig{
+                mtu: next_field,
+                invoking_packet: payload,
+            },
+            3 => TimeExceeded{
+                _unused: next_field,
+                invoking_packet: payload,
+            },
+            4 => ParameterProblem {
+                pointer: next_field,
+                invoking_packet: payload,
+            },
+            100 | 101 | 200 | 201 =>  PrivateExperimental{
+                padding: next_field,
+                payload: payload, 
+            },
+            128 => EchoRequest{
+                identifier: BigEndian::read_u16(&bytes[4..5]),
+                sequence: BigEndian::read_u16(&bytes[6..7]),
+                payload: payload,
+            },
+            129 => EchoReply{
+                identifier: BigEndian::read_u16(&bytes[4..5]),
+                sequence: BigEndian::read_u16(&bytes[6..7]),
+                payload: payload,
+            },
+            _ => return Err(PacketParseError::UnrecognizedICMPType),
+        };
+        return Ok(Icmpv6Packet{
+            typ: typ,
+            code: code,
+            checksum: checksum,
+            message: message,
+        })
+    }
+
+    /// Get this packet serialized to bytes suitable for sending on the wire.
+    pub fn get_bytes(&self, with_checksum: bool) -> Vec<u8> {
+        let mut bytes = Vec::new();
+        bytes.push(self.typ);
+        bytes.push(self.code);
+        let mut buf = Vec::with_capacity(2);
+        buf.resize(2, 0);
+        BigEndian::write_u16(&mut buf, if with_checksum {
+            self.checksum
+        } else {
+            0
+        });
+        bytes.append(&mut buf);
+        bytes.append(&mut self.message.get_bytes());
+        return bytes;
+    }
+
+    /// Calculate the checksum for the packet given the provided source and destination
+    /// addresses.
+    pub fn calculate_checksum(&self, source: &Ipv6Addr, dest: &Ipv6Addr) -> u16 {
+        // First sum the pseudo header
+        let mut sum = 0u32;
+        sum += ipv6_sum_words(source);
+        sum += ipv6_sum_words(dest);
+        // according to rfc4443: https://tools.ietf.org/html/rfc4443#section-2.3
+        // the ip next header value is 58
+        sum += 58u32;
+
+        let bytes = self.get_bytes(false);
+        let len = bytes.len();
+        sum += len as u32;
+        // Then append the message bytes as a byte buffer starting with the message
+        // type field with the checksum field set to 0.
+        sum += sum_big_endian_words(&bytes);
+        
+        // handle the carry
+        while sum >> 16 != 0 {
+            sum = (sum >> 16) + (sum & 0xFFFF);
+        }
+        !sum as u16
+    }
+
+    /// Fill the checksum for the packet using the given source and destination
+    /// addresses.
+    pub fn with_checksum(mut self, source: &Ipv6Addr, dest: &Ipv6Addr) -> Self {
+        self.checksum = self.calculate_checksum(source, dest);
+        self
+    }
+
+    /// Construct a packet for Destination Unreachable messages.
+    pub fn with_unreachable(code: u8, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
+        if code > 6 {
+            return Err(Icmpv6PacketBuildError::InvalidCode(code));
+        }
+        Ok(Self {
+            typ: 1,
+            code: code,
+            checksum: 0,
+            // TODO(jwall): Should we enforce that the packet isn't too big?
+            // It is not supposed to be larger than the minimum IPv6 MTU
+            message: Unreachable{
+                _unused: 0,
+                invoking_packet: packet,
+            },
+        })
+    }
+   
+    /// Construct a packet for Packet Too Big messages.
+    pub fn with_packet_too_big(mtu: u32, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
+        Ok(Self{
+            typ: 2,
+            code: 0,
+            checksum: 0,
+            // TODO(jwall): Should we enforce that the packet isn't too big?
+            // It is not supposed to be larger than the minimum IPv6 MTU
+            message: PacketTooBig{
+                mtu: mtu,
+                invoking_packet: packet,
+            },
+        })
+    }
+   
+    /// Construct a packet for Time Exceeded messages.
+    pub fn with_time_exceeded(code: u8, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
+        if code > 1 {
+            return Err(Icmpv6PacketBuildError::InvalidCode(code));
+        }
+        Ok(Self{
+            typ: 3,
+            code: code,
+            checksum: 0,
+            // TODO(jwall): Should we enforce that the packet isn't too big?
+            // It is not supposed to be larger than the minimum IPv6 MTU
+            message: TimeExceeded{
+                _unused: 0,
+                invoking_packet: packet,
+            },
+        })
+    }
+
+    /// Construct a packet for Parameter Problem messages.
+    pub fn with_parameter_problem(code: u8, pointer: u32, packet: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
+        if code > 1 {
+            return Err(Icmpv6PacketBuildError::InvalidCode(code));
+        }
+        Ok(Self {
+            typ: 4,
+            code: code,
+            checksum: 0,
+            message: ParameterProblem{
+                pointer: pointer,
+                invoking_packet: packet,
+            }
+        })
+    }
+
+    /// Construct a packet for Echo Request messages.
+    pub fn with_echo_request(identifier: u16, sequence: u16, payload: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
+        Ok(Self {
+            typ: 4,
+            code: 0,
+            checksum: 0,
+            message: EchoRequest{
+                identifier: identifier,
+                sequence: sequence,
+                payload: payload,
+            }
+        })
+    }
+
+    /// Construct a packet for Echo Reply messages.
+    pub fn with_echo_reply(identifier: u16, sequence: u16, payload: Vec<u8>) -> Result<Self, Icmpv6PacketBuildError> {
+        Ok(Self {
+            typ: 4,
+            code: 0,
+            checksum: 0,
+            message: EchoReply{
+                identifier: identifier,
+                sequence: sequence,
+                payload: payload,
+            }
+        })
+    }
+}
+
+pub enum Icmpv6PacketBuildError {
+    InvalidCode(u8),
+}

src/socket.rs

@@ -12,11 +12,13 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::convert::{TryFrom, Into, TryInto};
+use std::convert::{TryFrom, Into};
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
 
 use socket2::{Socket, Domain, Type, Protocol};
 
+use crate::packet::Icmpv6Packet;
+
 fn ip_to_socket(ip: &IpAddr) -> SocketAddr {
     format!("{}:0", ip).parse::<SocketAddr>().unwrap()
 }
@@ -52,10 +54,8 @@ impl IcmpSocket4 {
         Ok(())
     }
 
+    // TODO(jwall): This should take an actual packet not the payload.
     pub fn send_to(&mut self, dest: Ipv4Addr, payload: &[u8]) -> std::io::Result<()> {
-        //let packet = packet::icmp::Builder::default()
-        //    .echo().unwrap().request().unwrap().identifier(42).unwrap().sequence(seq)
-        //    .unwrap().payload(payload).unwrap().build().unwrap();
         let dest = ip_to_socket(&IpAddr::V4(dest));
         self.inner.set_ttl(self.opts.hops)?;
         self.inner.send_to(payload, &(dest.into()))?;
@@ -95,100 +95,42 @@ impl IcmpSocket6 {
         Ok(())
     }
 
-    pub fn send_to(&mut self, dest: Ipv6Addr, payload: &[u8]) -> std::io::Result<()> {
-        //let packet = packet::icmp::Builder::default()
-        //    .echo().unwrap().request().unwrap().identifier(42).unwrap().sequence(seq)
-        //    .unwrap().payload(payload).unwrap().build().unwrap();
+    // TODO(jwall): This should take an actual packet not the payload.
+    pub fn send_to(&mut self, dest: Ipv6Addr, mut packet: Icmpv6Packet) -> std::io::Result<()> {
+        let source = match self.bound_to {
+            Some(ref addr) => addr,
+            None => return Err(std::io::Error::new(std::io::ErrorKind::Other, "Socket not bound to an address")),
+        };
+        packet = packet.with_checksum(source, &dest);
         let dest = ip_to_socket(&IpAddr::V6(dest));
         self.inner.set_unicast_hops_v6(self.opts.hops)?;
-        self.inner.send_to(&payload, &(dest.into()))?;
+        self.inner.send_to(&packet.get_bytes(true), &(dest.into()))?;
         Ok(())
     }
    
-    
+    // TODO(jwall): This should return a packet not bytes.
     pub fn rcv_from(&self, buf: &mut [u8]) -> std::io::Result<usize> {
         let (read_count, _addr) = self.inner.recv_from(buf)?;
         Ok(read_count)
     }
 }
 
-pub enum IcmpSocket {
-    V4(IcmpSocket4),
-    V6(IcmpSocket6),
-}
-
-use IcmpSocket::{V4, V6};
-
-impl IcmpSocket {
-    pub fn new_v4() -> std::io::Result<Self> {
-        Ok(V4(IcmpSocket4::new()?))        
-    }
-    
-    pub fn new_v6() -> std::io::Result<Self> {
-        Ok(V6(IcmpSocket6::new()?))        
-    }
-
-    pub fn with_ip(ip: IpAddr) -> std::io::Result<Self>  {
-        ip.try_into()
-    }
-
-    pub fn set_max_hops(&mut self, hops: u32) {
-        match self {
-            V4(ref mut s) => s.set_max_hops(hops),
-            V6(ref mut s) => s.set_max_hops(hops),
-        }
-    }
-    pub fn send_to(&mut self, dest: IpAddr, payload: &[u8]) -> std::io::Result<()> {
-        match dest {
-            IpAddr::V4(ip) => if let V4(ref mut sock) = self {
-                sock.send_to(ip, payload)?;
-            } else {
-                return Err(std::io::Error::new(std::io::ErrorKind::Other, format!("Attempt to send to IPv4 dest {} from IPv6 source", ip)));
-            },
-            IpAddr::V6(ip) => if let V6(ref mut sock) = self {
-                sock.send_to(ip, payload)?;
-            } else {
-                return Err(std::io::Error::new(std::io::ErrorKind::Other, format!("Attempt to send to IPv6 dest {} from IPv4 source", ip)));
-            },
-        }
-        Ok(())
-    }
-
-    pub fn rcv_from(&self, buf: &mut [u8]) -> std::io::Result<usize> {
-        match self {
-            V4(ref s) => s.rcv_from(buf),
-            V6(ref s) => s.rcv_from(buf),
-        }
-    }
-}
-
-impl TryFrom<IpAddr> for IcmpSocket {
-    type Error = std::io::Error;
-
-    fn try_from(addr: IpAddr) -> Result<Self, Self::Error> {
-        match addr {
-           IpAddr::V4(addr) => addr.try_into(),
-           IpAddr::V6(addr) => addr.try_into(),
-        }
-    }
-}
-
-impl TryFrom<Ipv4Addr> for IcmpSocket {
+impl TryFrom<Ipv4Addr> for IcmpSocket4 {
     type Error = std::io::Error;
 
     fn try_from(addr: Ipv4Addr) -> Result<Self, Self::Error> {
         let mut sock = IcmpSocket4::new()?;
         sock.bind(addr)?;
-        Ok(IcmpSocket::V4(sock)) 
+        Ok(sock)
     }
 }
 
-impl TryFrom<Ipv6Addr> for IcmpSocket {
+impl TryFrom<Ipv6Addr> for IcmpSocket6 {
     type Error = std::io::Error;
 
     fn try_from(addr: Ipv6Addr) -> Result<Self, Self::Error> {
         let mut sock = IcmpSocket6::new()?;
         sock.bind(addr)?;
-        Ok(IcmpSocket::V6(sock)) 
+        Ok(sock) 
     }
 }