feat: add path type with metadata and basic daemon requests (#24)

* feat(daemon): add basic types and requests

* refactor: address review comments

* refactor: opaque PathParseError

* refactor: reorganize path module

* feat: use StandardPath within Path

* feat: check lengths of path-metadata vectors

* test(paths): extend and improve tests

* refactor(path): minor reorganization and some tests

* fix: address review comments

* refactor: use Paths iterator type

.github/workflows/rust.yml

@@ -102,10 +102,10 @@ jobs:
         with:
           save-if: "false"
       - run: sudo apt-get install protobuf-compiler
-      - run: cargo install cargo-tarpaulin@0.26.1
+      - run: cargo install cargo-tarpaulin@0.27.1
 
       - name: Run tests and record coverage
-        run: cargo tarpaulin --workspace --skip-clean --all-targets --doc --out html --out xml
+        run: cargo tarpaulin --workspace --skip-clean --all-targets --doc --out html --out xml --exclude-files "crates/scion-grpc/*"
 
       - name: Upload coverage report
         uses: actions/upload-artifact@v3

crates/scion/Cargo.toml

@@ -6,5 +6,12 @@ publish = false
 
 [dependencies]
 bytes = "1.5.0"
+chrono = { version = "0.4.31", default-features = false }
+scion-grpc = { version = "0.1.0", path = "../scion-grpc" }
 serde = { version = "1.0.188", features = ["derive"] }
 thiserror = "1.0.48"
+tonic = "0.10.2"
+tracing = "0.1.40"
+
+[dev-dependencies]
+prost-types = "0.12.2"

crates/scion/src/daemon.rs

@@ -1,2 +1,5 @@
-mod types;
-pub use types::{AsInfo, PathRequestFlags};
+mod messages;
+pub use messages::{AsInfo, PathRequest};
+
+mod client;
+pub use client::{DaemonClient, DaemonClientError};

crates/scion/src/daemon/client.rs

@@ -0,0 +1,112 @@
+use scion_grpc::daemon::{v1 as daemon_grpc, v1::daemon_service_client::DaemonServiceClient};
+use thiserror::Error;
+use tonic::transport::Channel;
+use tracing::warn;
+
+use super::{messages::PathRequest, AsInfo};
+use crate::{address::IsdAsn, packet::ByEndpoint, path::Path};
+
+#[derive(Debug, Error)]
+pub enum DaemonClientError {
+    #[error("A communication error occurred: {0}")]
+    ConnectionError(#[from] tonic::transport::Error),
+    #[error("A gRPC error occurred: {0}")]
+    GrpcError(#[from] tonic::Status),
+    #[error("Response contained invalid data")]
+    InvalidData,
+}
+
+/// A service to communicate with the local SCION daemon
+#[derive(Clone, Debug)]
+pub struct DaemonClient {
+    connection: Channel,
+    local_isd_asn: IsdAsn,
+}
+
+impl DaemonClient {
+    /// Create a new client to communicate with the SCION daemon located at `address`
+    ///
+    /// This attempts to connect to the daemon directly and fetch the local ISD-ASN.
+    ///
+    /// Errors:
+    ///
+    /// This returns an error, if any error occurs during the connection setup or during the request
+    /// for the AS info.
+    pub async fn connect(address: &str) -> Result<Self, DaemonClientError> {
+        let mut client = Self {
+            connection: tonic::transport::Endpoint::new(address.to_string())?
+                .connect()
+                .await?,
+            local_isd_asn: IsdAsn::WILDCARD,
+        };
+        client.local_isd_asn = client.as_info(IsdAsn::WILDCARD).await?.isd_asn;
+
+        Ok(client)
+    }
+
+    /// Request information about an AS; [`IsdAsn::WILDCARD`] can be used to obtain information
+    /// about the local AS.
+    pub async fn as_info(&self, isd_asn: IsdAsn) -> Result<AsInfo, DaemonClientError> {
+        self.client()
+            .r#as(daemon_grpc::AsRequest::from(isd_asn))
+            .await?
+            .into_inner()
+            .try_into()
+            .map_err(|_| DaemonClientError::InvalidData)
+    }
+
+    /// Request a set of end-to-end paths between the source and destination AS
+    pub async fn paths(&self, request: &PathRequest) -> Result<Paths, DaemonClientError> {
+        let src_isd_asn = if request.source.is_wildcard() {
+            self.local_isd_asn
+        } else {
+            request.source
+        };
+        let isd_asn = ByEndpoint {
+            source: src_isd_asn,
+            destination: request.destination,
+        };
+        Ok(Paths {
+            isd_asn,
+            grpc_paths: self
+                .client()
+                .paths(daemon_grpc::PathsRequest::from(request))
+                .await?
+                .into_inner()
+                .paths
+                .into_iter(),
+        })
+    }
+
+    #[inline]
+    pub async fn paths_to(
+        &self,
+        destination: IsdAsn,
+    ) -> Result<impl Iterator<Item = Path>, DaemonClientError> {
+        self.paths(&PathRequest::new(destination)).await
+    }
+
+    fn client(&self) -> DaemonServiceClient<Channel> {
+        DaemonServiceClient::new(self.connection.clone())
+    }
+}
+
+/// Iterator for SCION [Path]s obtained from the SCION Daemon via gRPC
+pub struct Paths {
+    isd_asn: ByEndpoint<IsdAsn>,
+    grpc_paths: std::vec::IntoIter<daemon_grpc::Path>,
+}
+
+impl Iterator for Paths {
+    type Item = Path;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        for grpc_path in self.grpc_paths.by_ref() {
+            match Path::try_from_grpc_with_endpoints(grpc_path, self.isd_asn) {
+                Ok(path) => return Some(path),
+                Err(e) => warn!(?e, "a parse error occurred for a path"),
+            }
+        }
+        None
+    }
+}

crates/scion/src/daemon/messages.rs

@@ -0,0 +1,170 @@
+use std::num::TryFromIntError;
+
+use scion_grpc::daemon::v1::{self as daemon_grpc};
+
+use crate::address::IsdAsn;
+
+impl From<IsdAsn> for daemon_grpc::AsRequest {
+    fn from(value: IsdAsn) -> Self {
+        Self {
+            isd_as: value.as_u64(),
+        }
+    }
+}
+
+/// Information about an AS
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+pub struct AsInfo {
+    /// The AS's ISD-ASN
+    pub isd_asn: IsdAsn,
+    /// Is the AS a core AS?
+    pub core: bool,
+    /// The maximum transmission unit (MTU) in the AS
+    pub mtu: u16,
+}
+
+impl TryFrom<daemon_grpc::AsResponse> for AsInfo {
+    type Error = TryFromIntError;
+    fn try_from(value: daemon_grpc::AsResponse) -> Result<Self, Self::Error> {
+        Ok(Self {
+            isd_asn: value.isd_as.into(),
+            core: value.core,
+            mtu: value.mtu.try_into()?,
+        })
+    }
+}
+
+/// Path requests specifying source and destination ISD-ASN with some flags
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+pub struct PathRequest {
+    pub source: IsdAsn,
+    pub destination: IsdAsn,
+    pub flags: PathRequestFlags,
+}
+
+/// Flags for path requests
+#[derive(Copy, Clone, Debug, Default, PartialEq, Eq, Hash)]
+pub struct PathRequestFlags {
+    pub refresh: bool,
+    pub hidden: bool,
+}
+
+impl From<&PathRequest> for daemon_grpc::PathsRequest {
+    fn from(value: &PathRequest) -> Self {
+        Self {
+            source_isd_as: value.source.as_u64(),
+            destination_isd_as: value.destination.as_u64(),
+            refresh: value.flags.refresh,
+            hidden: value.flags.hidden,
+        }
+    }
+}
+
+impl PathRequest {
+    pub fn new(dst_isd_asn: IsdAsn) -> Self {
+        Self {
+            source: IsdAsn::WILDCARD,
+            destination: dst_isd_asn,
+            flags: PathRequestFlags::default(),
+        }
+    }
+
+    pub fn with_src_isd_asn(mut self, src_isd_asn: IsdAsn) -> Self {
+        self.source = src_isd_asn;
+        self
+    }
+
+    pub fn with_refresh(mut self) -> Self {
+        self.flags.refresh = true;
+        self
+    }
+
+    pub fn with_hidden(mut self) -> Self {
+        self.flags.hidden = true;
+        self
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    mod as_info {
+        use super::*;
+
+        #[test]
+        fn request_conversion() {
+            assert_eq!(
+                daemon_grpc::AsRequest::from(IsdAsn::from(42)),
+                daemon_grpc::AsRequest { isd_as: 42 }
+            )
+        }
+
+        #[test]
+        fn response_conversion() {
+            assert_eq!(
+                AsInfo::try_from(daemon_grpc::AsResponse {
+                    isd_as: 42,
+                    core: true,
+                    mtu: 1500
+                }),
+                Ok(AsInfo {
+                    isd_asn: IsdAsn::from(42),
+                    core: true,
+                    mtu: 1500
+                })
+            )
+        }
+    }
+
+    mod path {
+        use super::*;
+
+        #[test]
+        fn grpc_conversion() {
+            assert_eq!(
+                daemon_grpc::PathsRequest::from(&PathRequest::new(IsdAsn::from(1))),
+                daemon_grpc::PathsRequest {
+                    source_isd_as: 0,
+                    destination_isd_as: 1,
+                    refresh: false,
+                    hidden: false,
+                }
+            )
+        }
+
+        #[test]
+        fn full_construction() {
+            let source = IsdAsn::from(42);
+            let destination = IsdAsn::from(314);
+            let request = PathRequest::new(destination);
+            assert_eq!(
+                request,
+                PathRequest {
+                    source: IsdAsn::WILDCARD,
+                    destination,
+                    flags: PathRequestFlags::default()
+                }
+            );
+            assert_eq!(
+                request.with_src_isd_asn(source),
+                PathRequest {
+                    source,
+                    destination,
+                    flags: PathRequestFlags::default()
+                }
+            );
+            assert_eq!(
+                request.with_hidden().with_refresh(),
+                PathRequest {
+                    source: IsdAsn::WILDCARD,
+                    destination,
+                    flags: PathRequestFlags {
+                        refresh: true,
+                        hidden: true
+                    }
+                }
+            );
+        }
+    }
+}

crates/scion/src/packet.rs

@@ -8,7 +8,7 @@
 use bytes::{Buf, Bytes};
 
 use crate::{
-    path::PathErrorKind,
+    path::DataplanePathErrorKind,
     wire_encoding::{WireDecode, WireDecodeWithContext},
 };
 
@@ -24,8 +24,8 @@ pub use path_header::PathHeader;
 /// Instances of an object associated with both a source and destination endpoint.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub struct ByEndpoint<T> {
-    destination: T,
-    source: T,
+    pub destination: T,
+    pub source: T,
 }
 
 /// A SCION network packet.
@@ -92,11 +92,11 @@ pub enum DecodeError {
     #[error("attempted to decode the empty path type")]
     EmptyPath,
     #[error("invalid path header: {0}")]
-    InvalidPath(PathErrorKind),
+    InvalidPath(DataplanePathErrorKind),
 }
 
-impl From<PathErrorKind> for DecodeError {
-    fn from(value: PathErrorKind) -> Self {
+impl From<DataplanePathErrorKind> for DecodeError {
+    fn from(value: DataplanePathErrorKind) -> Self {
         Self::InvalidPath(value)
     }
 }