feat: add datagram trait and path-aware datagram (#106)

crates/scion-proto/src/address/scion_address.rs

@@ -62,6 +62,16 @@ impl ScionAddr {
     }
 }
 
+impl AsRef<IsdAsn> for ScionAddr {
+    fn as_ref(&self) -> &IsdAsn {
+        match self {
+            ScionAddr::V4(addr) => addr.as_ref(),
+            ScionAddr::V6(addr) => addr.as_ref(),
+            ScionAddr::Svc(addr) => addr.as_ref(),
+        }
+    }
+}
+
 macro_rules! impl_from {
     ($base:ty, $variant:expr) => {
         impl From<$base> for ScionAddr {
@@ -155,6 +165,12 @@ macro_rules! scion_address {
             }
         }
 
+        impl AsRef<IsdAsn> for $name {
+            fn as_ref(&self) -> &IsdAsn {
+                &self.isd_asn
+            }
+        }
+
         impl core::fmt::Display for $name {
             fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
                 write!(f, "{},{}", self.isd_asn(), self.host())

crates/scion-proto/src/address/socket_address.rs

@@ -113,6 +113,16 @@ impl SocketAddr {
     }
 }
 
+impl AsRef<IsdAsn> for SocketAddr {
+    fn as_ref(&self) -> &IsdAsn {
+        match self {
+            SocketAddr::V4(addr) => addr.as_ref(),
+            SocketAddr::V6(addr) => addr.as_ref(),
+            SocketAddr::Svc(addr) => addr.as_ref(),
+        }
+    }
+}
+
 impl From<SocketAddrV4> for SocketAddr {
     /// Converts a [`SocketAddrV4`] into a [`SocketAddr::V4`].
     #[inline]
@@ -244,6 +254,12 @@ macro_rules! socket_address {
                 Ok(Self {scion_addr, port })
             }
         }
+
+        impl AsRef<IsdAsn> for $name {
+            fn as_ref(&self) -> &IsdAsn {
+                self.scion_addr.as_ref()
+            }
+        }
     };
 }
 

crates/scion-proto/src/datagram.rs

@@ -30,7 +30,7 @@ pub enum UdpEncodeError {
 ///
 /// [RFC]: https://www.ietf.org/archive/id/draft-dekater-scion-dataplane-00.html
 #[derive(Debug, Default, PartialEq)]
-pub struct UdpDatagram {
+pub struct UdpMessage {
     /// The source and destination ports
     pub port: ByEndpoint<u16>,
     /// The length of the header and payload
@@ -41,7 +41,7 @@ pub struct UdpDatagram {
     pub payload: Bytes,
 }
 
-impl UdpDatagram {
+impl UdpMessage {
     /// SCION protocol number for UDP.
     ///
     /// See the [IETF SCION-dataplane RFC draft][rfc] for possible values.
@@ -89,7 +89,7 @@ impl UdpDatagram {
     }
 }
 
-impl WireEncodeVec<2> for UdpDatagram {
+impl WireEncodeVec<2> for UdpMessage {
     type Error = InadequateBufferSize;
 
     fn encode_with_unchecked(&self, buffer: &mut BytesMut) -> [Bytes; 2] {
@@ -111,11 +111,11 @@ impl WireEncodeVec<2> for UdpDatagram {
     }
 }
 
-impl<T: Buf> WireDecode<T> for UdpDatagram {
+impl<T: Buf> WireDecode<T> for UdpMessage {
     type Error = UdpDecodeError;
 
     fn decode(data: &mut T) -> Result<Self, Self::Error> {
-        if data.remaining() < UdpDatagram::HEADER_LEN {
+        if data.remaining() < UdpMessage::HEADER_LEN {
             return Err(Self::Error::DatagramEmptyOrTruncated);
         }
 
@@ -161,7 +161,7 @@ mod tests {
                 destination: MaybeEncoded::Decoded(Ipv4Addr::from_str("10.0.0.2")?.into()),
             },
         };
-        let mut datagram = UdpDatagram::new(
+        let mut datagram = UdpMessage::new(
             ByEndpoint {
                 source: 10001,
                 destination: 10002,
@@ -193,7 +193,7 @@ mod tests {
         let mut encoded_bytes = BytesMut::new();
         encoded_bytes.put(encoded_datagram[0].clone());
         encoded_bytes.put(encoded_datagram[1].clone());
-        assert_eq!(UdpDatagram::decode(&mut encoded_bytes.freeze())?, datagram);
+        assert_eq!(UdpMessage::decode(&mut encoded_bytes.freeze())?, datagram);
 
         Ok(())
     }

crates/scion-proto/src/packet/udp.rs

@@ -5,7 +5,7 @@ use bytes::Bytes;
 use super::{InadequateBufferSize, ScionHeaders, ScionPacketRaw};
 use crate::{
     address::SocketAddr,
-    datagram::{UdpDatagram, UdpDecodeError},
+    datagram::{UdpDecodeError, UdpMessage},
     packet::{ByEndpoint, EncodeError},
     path::Path,
     wire_encoding::{WireDecode, WireEncodeVec},
@@ -16,7 +16,7 @@ pub struct ScionPacketUdp {
     /// Packet headers
     pub headers: ScionHeaders,
     /// The contained UDP datagram
-    pub datagram: UdpDatagram,
+    pub datagram: UdpMessage,
 }
 
 impl ScionPacketUdp {
@@ -62,11 +62,11 @@ impl ScionPacketUdp {
         let headers = ScionHeaders::new(
             endhosts,
             path,
-            UdpDatagram::PROTOCOL_NUMBER,
-            payload.len() + UdpDatagram::HEADER_LEN,
+            UdpMessage::PROTOCOL_NUMBER,
+            payload.len() + UdpMessage::HEADER_LEN,
         )?;
         let mut datagram =
-            UdpDatagram::new(endhosts.map(|e| e.port()), payload).map_err(|_| todo!())?;
+            UdpMessage::new(endhosts.map(|e| e.port()), payload).map_err(|_| todo!())?;
         datagram.set_checksum(&headers.address);
 
         Ok(Self { headers, datagram })
@@ -77,14 +77,14 @@ impl TryFrom<ScionPacketRaw> for ScionPacketUdp {
     type Error = UdpDecodeError;
 
     fn try_from(mut value: ScionPacketRaw) -> Result<Self, Self::Error> {
-        if value.headers.common.next_header != UdpDatagram::PROTOCOL_NUMBER {
+        if value.headers.common.next_header != UdpMessage::PROTOCOL_NUMBER {
             return Err(UdpDecodeError::WrongProtocolNumber(
                 value.headers.common.next_header,
             ));
         }
         Ok(Self {
             headers: value.headers,
-            datagram: UdpDatagram::decode(&mut value.payload)?,
+            datagram: UdpMessage::decode(&mut value.payload)?,
         })
     }
 }

crates/scion-proto/src/path.rs

@@ -3,7 +3,7 @@
 //! This module contains types for SCION paths and metadata as well as encoding and decoding
 //! functions.
 
-use std::net::SocketAddr;
+use std::{net::SocketAddr, ops::Deref};
 
 use bytes::Bytes;
 use scion_grpc::daemon::v1 as daemon_grpc;
@@ -27,7 +27,7 @@ pub mod epic;
 pub use epic::EpicAuths;
 
 /// A SCION end-to-end path with optional metadata.
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone)]
 pub struct Path<T = Bytes> {
     /// The raw bytes to be added as the path header to SCION dataplane packets.
     pub dataplane_path: DataplanePath<T>,
@@ -125,6 +125,29 @@ impl Path<Bytes> {
     }
 }
 
+impl From<Path<&mut [u8]>> for Path<Bytes> {
+    fn from(value: Path<&mut [u8]>) -> Self {
+        Self {
+            dataplane_path: value.dataplane_path.into(),
+            underlay_next_hop: value.underlay_next_hop,
+            isd_asn: value.isd_asn,
+            metadata: value.metadata,
+        }
+    }
+}
+
+impl<T> PartialEq for Path<T>
+where
+    T: Deref<Target = [u8]>,
+{
+    fn eq(&self, other: &Self) -> bool {
+        self.dataplane_path == other.dataplane_path
+            && self.underlay_next_hop == other.underlay_next_hop
+            && self.isd_asn == other.isd_asn
+            && self.metadata == other.metadata
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use std::net::{IpAddr, Ipv4Addr};

crates/scion-proto/src/path/dataplane.rs

@@ -61,7 +61,7 @@ impl From<u8> for PathType {
 pub struct UnsupportedPathType(pub u8);
 
 /// Dataplane path found in a SCION packet.
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone)]
 pub enum DataplanePath<T = Bytes> {
     /// The empty path type, used for intra-AS hops.
     EmptyPath,
@@ -131,6 +131,17 @@ where
         }
     }
 
+    /// Reverse the path to the provided slice.
+    ///
+    /// Unsupported path types are copied to the slice, as is.
+    pub fn reverse_to_slice<'b>(&self, buffer: &'b mut [u8]) -> DataplanePath<&'b mut [u8]> {
+        match self {
+            DataplanePath::EmptyPath => DataplanePath::EmptyPath,
+            DataplanePath::Standard(path) => DataplanePath::Standard(path.reverse_to_slice(buffer)),
+            DataplanePath::Unsupported { .. } => self.copy_to_slice(buffer),
+        }
+    }
+
     /// Reverses the path.
     pub fn to_reversed(&self) -> Result<DataplanePath, UnsupportedPathType> {
         match self {
@@ -188,6 +199,30 @@ impl From<StandardPath> for DataplanePath {
     }
 }
 
+impl<T, U> PartialEq<DataplanePath<U>> for DataplanePath<T>
+where
+    T: Deref<Target = [u8]>,
+    U: Deref<Target = [u8]>,
+{
+    fn eq(&self, other: &DataplanePath<U>) -> bool {
+        match (self, other) {
+            (Self::Standard(lhs), DataplanePath::Standard(rhs)) => lhs.raw() == rhs.raw(),
+            (
+                Self::Unsupported {
+                    path_type: l_path_type,
+                    bytes: l_bytes,
+                },
+                DataplanePath::Unsupported {
+                    path_type: r_path_type,
+                    bytes: r_bytes,
+                },
+            ) => l_path_type == r_path_type && l_bytes.deref() == r_bytes.deref(),
+            (Self::EmptyPath, DataplanePath::EmptyPath) => true,
+            _ => false,
+        }
+    }
+}
+
 impl WireEncode for DataplanePath {
     type Error = InadequateBufferSize;
 
@@ -275,7 +310,7 @@ mod tests {
 
     #[test]
     fn reverse_empty() {
-        let dataplane_path = DataplanePath::EmptyPath;
+        let dataplane_path = DataplanePath::<Bytes>::EmptyPath;
         let reverse_path = dataplane_path.to_reversed().unwrap();
         assert_eq!(dataplane_path, reverse_path);
         assert_eq!(reverse_path.to_reversed().unwrap(), dataplane_path);

crates/scion-proto/src/reliable/registration.rs

@@ -29,7 +29,7 @@ use bytes::{Buf, BufMut};
 use super::wire_utils::LAYER4_PORT_OCTETS;
 use crate::{
     address::{HostType, IsdAsn, ServiceAddr, SocketAddr as ScionSocketAddr},
-    datagram::UdpDatagram,
+    datagram::UdpMessage,
     reliable::{
         wire_utils::{encoded_address_and_port_length, encoded_address_length},
         ADDRESS_TYPE_OCTETS,
@@ -85,7 +85,7 @@ impl RegistrationRequest {
 
         self.encode_command_flag(buffer);
 
-        buffer.put_u8(UdpDatagram::PROTOCOL_NUMBER);
+        buffer.put_u8(UdpMessage::PROTOCOL_NUMBER);
         buffer.put_u64(self.isd_asn.as_u64());
 
         encode_address(buffer, &self.public_address);

crates/scion/Cargo.toml

@@ -6,6 +6,7 @@ license = "Apache-2.0"
 publish = false
 
 [dependencies]
+async-trait = "0.1.74"
 bytes = "1.5.0"
 chrono = { workspace = true, features = ["clock"] }
 scion-grpc = { version = "0.1.0", path = "../scion-grpc" }

crates/scion/src/lib.rs

@@ -2,4 +2,5 @@
 
 pub mod daemon;
 pub mod dispatcher;
+pub mod pan;
 pub mod udp_socket;

crates/scion/src/pan.rs

@@ -0,0 +1,9 @@
+//! Path aware networking socket and services.
+mod datagram;
+pub use datagram::{AsyncScionDatagram, PathAwareDatagram};
+
+mod path_service;
+pub use path_service::AsyncPathService;
+
+mod error;
+pub use error::{PathErrorKind, ReceiveError, SendError};