copy in iroh-car from iroh repo, verbatim

1 files changed, 104 insertions, 0 deletions

diff --git a/iroh-car/src/header.rs b/iroh-car/src/header.rs
new file mode 100644
index 0000000..c004e35
--- /dev/null
+++ b/iroh-car/src/header.rs
@@ -0,0 +1,104 @@
+use cid::Cid;
+use ipld::codec::Codec;
+use ipld_cbor::DagCborCodec;
+
+use crate::error::Error;
+
+/// A car header.
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
+pub enum CarHeader {
+    V1(CarHeaderV1),
+}
+
+impl CarHeader {
+    pub fn new_v1(roots: Vec<Cid>) -> Self {
+        Self::V1(roots.into())
+    }
+
+    pub fn decode(buffer: &[u8]) -> Result<Self, Error> {
+        let header: CarHeaderV1 = DagCborCodec
+            .decode(buffer)
+            .map_err(|e| Error::Parsing(e.to_string()))?;
+
+        if header.roots.is_empty() {
+            return Err(Error::Parsing("empty CAR file".to_owned()));
+        }
+
+        if header.version != 1 {
+            return Err(Error::InvalidFile(
+                "Only CAR file version 1 is supported".to_string(),
+            ));
+        }
+
+        Ok(CarHeader::V1(header))
+    }
+
+    pub fn encode(&self) -> Result<Vec<u8>, Error> {
+        match self {
+            CarHeader::V1(ref header) => {
+                let res = DagCborCodec.encode(header)?;
+                Ok(res)
+            }
+        }
+    }
+
+    pub fn roots(&self) -> &[Cid] {
+        match self {
+            CarHeader::V1(header) => &header.roots,
+        }
+    }
+
+    pub fn version(&self) -> u64 {
+        match self {
+            CarHeader::V1(_) => 1,
+        }
+    }
+}
+
+/// CAR file header version 1.
+#[derive(Debug, Clone, Default, ipld::DagCbor, PartialEq, Eq)]
+pub struct CarHeaderV1 {
+    #[ipld]
+    pub roots: Vec<Cid>,
+    #[ipld]
+    pub version: u64,
+}
+
+impl CarHeaderV1 {
+    /// Creates a new CAR file header
+    pub fn new(roots: Vec<Cid>, version: u64) -> Self {
+        Self { roots, version }
+    }
+}
+
+impl From<Vec<Cid>> for CarHeaderV1 {
+    fn from(roots: Vec<Cid>) -> Self {
+        Self { roots, version: 1 }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use ipld::codec::{Decode, Encode};
+    use ipld_cbor::DagCborCodec;
+    use multihash::MultihashDigest;
+
+    use super::*;
+
+    #[test]
+    fn symmetric_header_v1() {
+        let digest = multihash::Code::Blake2b256.digest(b"test");
+        let cid = Cid::new_v1(DagCborCodec.into(), digest);
+
+        let header = CarHeaderV1::from(vec![cid]);
+
+        let mut bytes = Vec::new();
+        header.encode(DagCborCodec, &mut bytes).unwrap();
+
+        assert_eq!(
+            CarHeaderV1::decode(DagCborCodec, &mut std::io::Cursor::new(&bytes)).unwrap(),
+            header
+        );
+    }
+}