feat: compute receipts root (#111)

Closes #106

---------

Co-authored-by: Tomás Grüner <47506558+MegaRedHand@users.noreply.github.com>

crates/core/src/types/block.rs

@@ -1,5 +1,6 @@
 use crate::{
     rlp::{encode::RLPEncode, structs::Encoder},
+    types::Receipt,
     Address, H256, U256,
 };
 use bytes::Bytes;
@@ -106,6 +107,27 @@ impl BlockBody {
     }
 }
 
+pub fn compute_receipts_root(receipts: Vec<Receipt>) -> H256 {
+    let receipts_iter: Vec<_> = receipts
+        .iter()
+        .enumerate()
+        .map(|(i, receipt)| {
+            // Key: RLP(index)
+            let mut k = Vec::new();
+            i.encode(&mut k);
+
+            // Value: tx_type || RLP(receipt)  if tx_type != 0
+            //                   RLP(receipt)  else
+            let mut v = Vec::new();
+            receipt.encode_with_type(&mut v);
+
+            (k, v)
+        })
+        .collect();
+    let root = PatriciaMerkleTree::<_, _, Keccak256>::compute_hash_from_sorted_iter(&receipts_iter);
+    H256(root.into())
+}
+
 impl RLPEncode for BlockBody {
     fn encode(&self, buf: &mut dyn bytes::BufMut) {
         Encoder::new(buf)

crates/core/src/types/receipt.rs

@@ -2,17 +2,48 @@ use crate::rlp::{encode::RLPEncode, structs::Encoder};
 use crate::types::Bloom;
 use bytes::Bytes;
 use ethereum_types::{Address, H256};
+
+use super::TxType;
 pub type Index = u64;
 
 /// Result of a transaction
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct Receipt {
+    tx_type: TxType,
     succeeded: bool,
     cumulative_gas_used: u64,
     bloom: Bloom,
     logs: Vec<Log>,
 }
 
+impl Receipt {
+    pub fn new(
+        tx_type: TxType,
+        succeeded: bool,
+        cumulative_gas_used: u64,
+        bloom: Bloom,
+        logs: Vec<Log>,
+    ) -> Self {
+        Self {
+            tx_type,
+            succeeded,
+            cumulative_gas_used,
+            bloom,
+            logs,
+        }
+    }
+
+    pub fn encode_with_type(&self, buf: &mut dyn bytes::BufMut) {
+        // tx_type || RLP(receipt)  if tx_type != 0
+        //            RLP(receipt)  else
+        match self.tx_type {
+            TxType::Legacy => {}
+            _ => buf.put_u8(self.tx_type as u8),
+        }
+        self.encode(buf);
+    }
+}
+
 impl RLPEncode for Receipt {
     fn encode(&self, buf: &mut dyn bytes::BufMut) {
         Encoder::new(buf)

crates/core/src/types/transaction.rs

@@ -284,9 +284,11 @@ fn recover_address(
 mod tests {
     use hex_literal::hex;
 
-    use super::LegacyTransaction;
     use crate::{
-        types::{BlockBody, Transaction, TxKind},
+        types::{
+            compute_receipts_root, BlockBody, LegacyTransaction, Receipt, Transaction, TxKind,
+            TxType,
+        },
         U256,
     };
 
@@ -315,4 +317,21 @@ mod tests {
 
         assert_eq!(result, expected_root.into());
     }
+
+    #[test]
+    fn test_compute_receipts_root() {
+        // example taken from
+        // https://github.com/ethereum/go-ethereum/blob/f8aa62353666a6368fb3f1a378bd0a82d1542052/cmd/evm/testdata/1/exp.json#L18
+        let tx_type = TxType::Legacy;
+        let succeeded = true;
+        let cumulative_gas_used = 0x5208;
+        let bloom = [0x00; 256];
+        let logs = vec![];
+        let receipt = Receipt::new(tx_type, succeeded, cumulative_gas_used, bloom, logs);
+
+        let result = compute_receipts_root(vec![receipt]);
+        let expected_root =
+            hex!("056b23fbba480696b65fe5a59b8f2148a1299103c4f57df839233af2cf4ca2d2");
+        assert_eq!(result, expected_root.into());
+    }
 }