fix: correct implementations of Encodable and Decodable for sidecars

crates/consensus/src/transaction/eip4844.rs

@@ -138,7 +138,7 @@ impl TxEip4844Variant {
             Self::TxEip4844WithSidecar(tx) => {
                 let payload_length = tx.tx().fields_len() + signature.rlp_vrs_len();
                 let inner_header = Header { list: true, payload_length };
-                inner_header.length() + payload_length + tx.sidecar().fields_len()
+                inner_header.length() + payload_length + tx.sidecar().rlp_encoded_fields_length()
             }
         };
 
@@ -875,7 +875,7 @@ impl TxEip4844WithSidecar {
         let inner_header = Header { list: true, payload_length: inner_payload_length };
 
         let outer_payload_length =
-            inner_header.length() + inner_payload_length + self.sidecar.fields_len();
+            inner_header.length() + inner_payload_length + self.sidecar.rlp_encoded_fields_length();
         let outer_header = Header { list: true, payload_length: outer_payload_length };
 
         // write the two headers
@@ -885,7 +885,7 @@ impl TxEip4844WithSidecar {
         // now write the fields
         self.tx.encode_fields(out);
         signature.write_rlp_vrs(out);
-        self.sidecar.encode(out);
+        self.sidecar.rlp_encode_fields(out);
     }
 
     /// Decodes the transaction from RLP bytes, including the signature.
@@ -910,7 +910,7 @@ impl TxEip4844WithSidecar {
         let inner_tx = TxEip4844::decode_signed_fields(buf)?;
 
         // decode the sidecar
-        let sidecar = BlobTransactionSidecar::decode(buf)?;
+        let sidecar = BlobTransactionSidecar::rlp_decode_fields(buf)?;
 
         if buf.len() + header.payload_length != original_len {
             return Err(alloy_rlp::Error::ListLengthMismatch {
@@ -1085,6 +1085,7 @@ mod tests {
         let len = expected_envelope.length();
         let mut buf = Vec::with_capacity(len);
         expected_envelope.encode(&mut buf);
+        dbg!(alloy_primitives::hex::encode(&buf[0..16]));
         assert_eq!(buf.len(), len);
 
         // ensure it's also the same size that `actual` claims to be, since we just changed the

crates/consensus/src/transaction/envelope.rs

@@ -288,7 +288,9 @@ impl TxEnvelope {
                     let inner_payload_length = tx.tx().fields_len() + t.signature().rlp_vrs_len();
                     let inner_header = Header { list: true, payload_length: inner_payload_length };
 
-                    inner_header.length() + inner_payload_length + tx.sidecar.fields_len()
+                    inner_header.length()
+                        + inner_payload_length
+                        + tx.sidecar.rlp_encoded_fields_length()
                 }
             },
             Self::Eip7702(t) => t.tx().fields_len() + t.signature().rlp_vrs_len(),

crates/eips/src/eip2718.rs

@@ -226,8 +226,8 @@ pub trait Encodable2718: Sized + Send + Sync + 'static {
         Sealed::new_unchecked(self, hash)
     }
 
-    /// The length of the 2718 encoded envelope in network format. This is the length of the header
-    /// + the length of the type flag and inner encoding.
+    /// The length of the 2718 encoded envelope in network format. This is the
+    /// length of the header + the length of the type flag and inner encoding.
     fn network_len(&self) -> usize {
         let mut payload_length = self.encode_2718_len();
         if !self.is_legacy() {

crates/eips/src/eip4844/sidecar.rs

@@ -5,7 +5,7 @@ use crate::eip4844::{
 };
 use alloc::boxed::Box;
 use alloy_primitives::{bytes::BufMut, B256};
-use alloy_rlp::{Decodable, Encodable};
+use alloy_rlp::{Decodable, Encodable, Header};
 
 #[cfg(any(test, feature = "arbitrary"))]
 use crate::eip4844::MAX_BLOBS_PER_BLOCK;
@@ -19,7 +19,7 @@ pub(crate) const VERSIONED_HASH_VERSION_KZG: u8 = 0x01;
 /// This represents a set of blobs, and its corresponding commitments and proofs.
 ///
 /// This type encodes and decodes the fields without an rlp header.
-#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
+#[derive(Clone, Default, PartialEq, Eq, Hash)]
 #[repr(C)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 #[doc(alias = "BlobTxSidecar")]
@@ -36,6 +36,16 @@ pub struct BlobTransactionSidecar {
     pub proofs: Vec<Bytes48>,
 }
 
+impl core::fmt::Debug for BlobTransactionSidecar {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        f.debug_struct("BlobTransactionSidecar")
+            .field("blobs", &self.blobs.len())
+            .field("commitments", &self.commitments)
+            .field("proofs", &self.proofs)
+            .finish()
+    }
+}
+
 impl IntoIterator for BlobTransactionSidecar {
     type Item = BlobTransactionSidecarItem;
     type IntoIter = alloc::vec::IntoIter<BlobTransactionSidecarItem>;
@@ -248,25 +258,6 @@ impl BlobTransactionSidecar {
         self.commitments.get(blob_index).map(|c| kzg_to_versioned_hash(c.as_slice()))
     }
 
-    /// Encodes the inner [BlobTransactionSidecar] fields as RLP bytes, __without__ a RLP header.
-    ///
-    /// This encodes the fields in the following order:
-    /// - `blobs`
-    /// - `commitments`
-    /// - `proofs`
-    #[inline]
-    pub(crate) fn encode_inner(&self, out: &mut dyn BufMut) {
-        // Encode the blobs, commitments, and proofs
-        self.blobs.encode(out);
-        self.commitments.encode(out);
-        self.proofs.encode(out);
-    }
-
-    /// Outputs the RLP length of the [BlobTransactionSidecar] fields, without a RLP header.
-    pub fn fields_len(&self) -> usize {
-        self.blobs.length() + self.commitments.length() + self.proofs.length()
-    }
-
     /// Calculates a size heuristic for the in-memory size of the [BlobTransactionSidecar].
     #[inline]
     pub fn size(&self) -> usize {
@@ -302,27 +293,84 @@ impl BlobTransactionSidecar {
 
         Ok(Self::from_kzg(blobs, commitments, proofs))
     }
+
+    /// Outputs the RLP length of the [BlobTransactionSidecar] fields, without
+    /// a RLP header.
+    #[doc(hidden)]
+    pub fn rlp_encoded_fields_length(&self) -> usize {
+        self.blobs.length() + self.commitments.length() + self.proofs.length()
+    }
+
+    /// Encodes the inner [BlobTransactionSidecar] fields as RLP bytes, __without__ a RLP header.
+    ///
+    /// This encodes the fields in the following order:
+    /// - `blobs`
+    /// - `commitments`
+    /// - `proofs`
+    #[inline]
+    #[doc(hidden)]
+    pub fn rlp_encode_fields(&self, out: &mut dyn BufMut) {
+        // Encode the blobs, commitments, and proofs
+        self.blobs.encode(out);
+        self.commitments.encode(out);
+        self.proofs.encode(out);
+    }
+
+    /// Creates an RLP header for the [BlobTransactionSidecar].
+    fn rlp_header(&self) -> Header {
+        Header { list: true, payload_length: self.rlp_encoded_fields_length() }
+    }
+
+    /// Calculates the length of the [BlobTransactionSidecar] when encoded as
+    /// RLP.
+    pub fn rlp_encoded_length(&self) -> usize {
+        self.rlp_header().length() + self.rlp_encoded_fields_length()
+    }
+
+    /// Encodes the [BlobTransactionSidecar] as RLP bytes.
+    pub fn rlp_encode(&self, out: &mut dyn BufMut) {
+        self.rlp_header().encode(out);
+        self.rlp_encode_fields(out);
+    }
+
+    /// RLP decode the fields of a [BlobTransactionSidecar].
+    #[doc(hidden)]
+    pub fn rlp_decode_fields(buf: &mut &[u8]) -> alloy_rlp::Result<Self> {
+        Ok(Self {
+            blobs: Decodable::decode(buf)?,
+            commitments: Decodable::decode(buf)?,
+            proofs: Decodable::decode(buf)?,
+        })
+    }
+
+    /// Decodes the [BlobTransactionSidecar] from RLP bytes.
+    pub fn rlp_decode(buf: &mut &[u8]) -> alloy_rlp::Result<Self> {
+        let header = Header::decode(buf)?;
+        if header.list {
+            return Err(alloy_rlp::Error::UnexpectedList);
+        }
+        if buf.len() < header.payload_length {
+            return Err(alloy_rlp::Error::InputTooShort);
+        }
+        Self::rlp_decode_fields(buf)
+    }
 }
 
 impl Encodable for BlobTransactionSidecar {
     /// Encodes the inner [BlobTransactionSidecar] fields as RLP bytes, without a RLP header.
-    fn encode(&self, s: &mut dyn BufMut) {
-        self.encode_inner(s);
+    fn encode(&self, out: &mut dyn BufMut) {
+        self.rlp_encode(out);
     }
 
     fn length(&self) -> usize {
-        self.fields_len()
+        self.rlp_encoded_length()
     }
 }
 
 impl Decodable for BlobTransactionSidecar {
     /// Decodes the inner [BlobTransactionSidecar] fields from RLP bytes, without a RLP header.
     fn decode(buf: &mut &[u8]) -> alloy_rlp::Result<Self> {
-        Ok(Self {
-            blobs: Decodable::decode(buf)?,
-            commitments: Decodable::decode(buf)?,
-            proofs: Decodable::decode(buf)?,
-        })
+        Self::rlp_decode(buf)
     }
 }