fix: correct encode_2718_len for legacy transactions (alloy-rs#1360)

* fix: correct  for legacy transactions

* simplify rlp_payload_length

* fmt

crates/consensus/src/transaction/envelope.rs

@@ -278,51 +278,24 @@ impl TxEnvelope {
         }
     }
 
-    /// Return the length of the inner txn, __without a type byte__.
-    pub fn inner_length(&self) -> usize {
-        match self {
+    /// Return the length of the inner txn, including type byte length
+    pub fn rlp_payload_length(&self) -> usize {
+        let payload_length = match self {
             Self::Legacy(t) => t.tx().fields_len() + t.signature().rlp_vrs_len(),
-            Self::Eip2930(t) => {
-                let payload_length = t.tx().fields_len() + t.signature().rlp_vrs_len();
-                Header { list: true, payload_length }.length() + payload_length
-            }
-            Self::Eip1559(t) => {
-                let payload_length = t.tx().fields_len() + t.signature().rlp_vrs_len();
-                Header { list: true, payload_length }.length() + payload_length
-            }
+            Self::Eip2930(t) => t.tx().fields_len() + t.signature().rlp_vrs_len(),
+            Self::Eip1559(t) => t.tx().fields_len() + t.signature().rlp_vrs_len(),
             Self::Eip4844(t) => match t.tx() {
-                TxEip4844Variant::TxEip4844(tx) => {
-                    let payload_length = tx.fields_len() + t.signature().rlp_vrs_len();
-                    Header { list: true, payload_length }.length() + payload_length
-                }
+                TxEip4844Variant::TxEip4844(tx) => tx.fields_len() + t.signature().rlp_vrs_len(),
                 TxEip4844Variant::TxEip4844WithSidecar(tx) => {
                     let inner_payload_length = tx.tx().fields_len() + t.signature().rlp_vrs_len();
                     let inner_header = Header { list: true, payload_length: inner_payload_length };
 
-                    let outer_payload_length =
-                        inner_header.length() + inner_payload_length + tx.sidecar.fields_len();
-                    let outer_header = Header { list: true, payload_length: outer_payload_length };
-
-                    outer_header.length() + outer_payload_length
+                    inner_header.length() + inner_payload_length + tx.sidecar.fields_len()
                 }
             },
-            Self::Eip7702(t) => {
-                let payload_length = t.tx().fields_len() + t.signature().rlp_vrs_len();
-                Header { list: true, payload_length }.length() + payload_length
-            }
-        }
-    }
-
-    /// Return the RLP payload length of the network-serialized wrapper
-    fn rlp_payload_length(&self) -> usize {
-        if let Self::Legacy(t) = self {
-            let payload_length = t.tx().fields_len() + t.signature().rlp_vrs_len();
-            return Header { list: true, payload_length }.length() + payload_length;
-        }
-        // length of inner tx body
-        let inner_length = self.inner_length();
-        // with tx type byte
-        inner_length + 1
+            Self::Eip7702(t) => t.tx().fields_len() + t.signature().rlp_vrs_len(),
+        };
+        Header { list: true, payload_length }.length() + payload_length + !self.is_legacy() as usize
     }
 }
 
@@ -375,7 +348,7 @@ impl Encodable2718 for TxEnvelope {
     }
 
     fn encode_2718_len(&self) -> usize {
-        self.inner_length() + !self.is_legacy() as usize
+        self.rlp_payload_length()
     }
 
     fn encode_2718(&self, out: &mut dyn alloy_rlp::BufMut) {
@@ -668,6 +641,23 @@ mod tests {
         assert_eq!(decoded, tx_envelope);
     }
 
+    #[test]
+    fn test_encode_decode_legacy() {
+        let tx = TxLegacy {
+            chain_id: None,
+            nonce: 2,
+            gas_limit: 1000000,
+            gas_price: 10000000000,
+            to: Address::left_padding_from(&[6]).into(),
+            value: U256::from(7_u64),
+            ..Default::default()
+        };
+        test_encode_decode_roundtrip(
+            tx,
+            Some(Signature::test_signature().with_parity(Parity::NonEip155(true))),
+        );
+    }
+
     #[test]
     fn test_encode_decode_eip1559() {
         let tx = TxEip1559 {