feat: add support to deserialize transaction with witness data (#259)

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- [ ] issue #
- [x] follows contribution
[guide](https://github.com/keep-starknet-strange/shinigami/blob/main/CONTRIBUTING.md)
- [x] code change includes tests

<!-- PR description below -->
This PR add support to deserialize transaction with witness data

Co-authored-by: Brandon Roberts <[email protected]>

packages/engine/src/transaction.cairo

@@ -173,9 +173,12 @@ pub impl EngineInternalTransactionImpl of EngineInternalTransactionTrait {
     fn btc_decode(raw: ByteArray, encoding: u32) -> EngineTransaction {
         let mut offset: usize = 0;
         let version: i32 = byte_array_value_at_le(@raw, ref offset, 4).try_into().unwrap();
+        if encoding == WITNESS_ENCODING {
+            // consume flags
+            offset += 2;
+        }
         // TODO: ReadVerIntBuf
         let input_len: u8 = byte_array_value_at_le(@raw, ref offset, 1).try_into().unwrap();
-        // TODO: input_len = 0 -> segwit
         // TODO: Error handling and bounds checks
         // TODO: Byte orderings
         let mut i = 0;
@@ -211,18 +214,62 @@ pub impl EngineInternalTransactionImpl of EngineInternalTransactionTrait {
             outputs.append(output);
             i += 1;
         };
-        // TODO: Witness
+
+        let mut inputs_with_witness: Array<EngineTransactionInput> = array![];
+
+        if encoding == WITNESS_ENCODING {
+            // one witness for each input
+            i = 0;
+            while i != input_len {
+                let witness_count: u8 = byte_array_value_at_le(@raw, ref offset, 1)
+                    .try_into()
+                    .unwrap();
+                let mut j = 0;
+                let mut witness: Array<ByteArray> = array![];
+                while j != witness_count {
+                    let script_len = byte_array_value_at_le(@raw, ref offset, 1)
+                        .try_into()
+                        .unwrap();
+                    let script = sub_byte_array(@raw, ref offset, script_len);
+                    witness.append(script);
+                    j += 1;
+                };
+                // update Transaction Input
+                let input = inputs.at(i.into());
+                let mut input_with_witness = input.clone();
+                input_with_witness.witness = witness;
+                inputs_with_witness.append(input_with_witness);
+                i += 1;
+            };
+        }
         let locktime: u32 = byte_array_value_at_le(@raw, ref offset, 4).try_into().unwrap();
-        EngineTransaction {
-            version: version,
-            transaction_inputs: inputs,
-            transaction_outputs: outputs,
-            locktime: locktime,
+
+        if encoding == WITNESS_ENCODING {
+            EngineTransaction {
+                version: version,
+                transaction_inputs: inputs_with_witness,
+                transaction_outputs: outputs,
+                locktime: locktime,
+            }
+        } else {
+            EngineTransaction {
+                version: version,
+                transaction_inputs: inputs,
+                transaction_outputs: outputs,
+                locktime: locktime,
+            }
         }
     }
 
     fn deserialize(raw: ByteArray) -> EngineTransaction {
-        Self::btc_decode(raw, WITNESS_ENCODING)
+        let mut offset: usize = 0;
+        let _version: i32 = byte_array_value_at_le(@raw, ref offset, 4).try_into().unwrap();
+        let flags: u16 = byte_array_value_at_le(@raw, ref offset, 2).try_into().unwrap();
+        if flags == 0x100 {
+            Self::btc_decode(raw, WITNESS_ENCODING)
+        } else {
+            Self::btc_decode(raw, BASE_ENCODING)
+        }
     }
 
     fn deserialize_no_witness(raw: ByteArray) -> EngineTransaction {

packages/tests/src/tests/test_transactions.cairo

@@ -121,6 +121,46 @@ fn test_deserialize_first_p2pkh_transaction() {
     assert_eq!(transaction.locktime, 0, "Lock time is not correct");
 }
 
+#[test]
+fn test_deserialize_p2wsh_transaction() {
+    // https://learnmeabitcoin.com/explorer/tx/64f427122f7951687aea608b5474509a30616d4e5773a83bc1ed8b8271ad1991
+    let raw_transaction_hex =
+        "0x020000000001018a39b5cdd48c7d45a31a89cd675a95f5de78aebeeda1e55ac35d7110c3bacfc60000000000ffffffff01204e0000000000001976a914ee63c8c790952de677d1f8019c9474d84098d6e188ac0202123423aa20a23421f2ba909c885a3077bb6f8eb4312487797693bbcfe7e311f797e3c5b8fa8700000000";
+    let raw_transaction = hex_to_bytecode(@raw_transaction_hex);
+    let transaction = EngineInternalTransactionTrait::deserialize(raw_transaction);
+
+    assert_eq!(transaction.version, 2, "Version is not correct");
+    assert_eq!(transaction.transaction_inputs.len(), 1, "Transaction inputs length is not correct");
+    let input0 = transaction.transaction_inputs[0];
+    let expected_txid_hex = "0x8a39b5cdd48c7d45a31a89cd675a95f5de78aebeeda1e55ac35d7110c3bacfc6";
+    let expected_txid = hex_to_bytecode(@expected_txid_hex);
+    let expected_witness_1_hex = "0x1234";
+    let expected_witness_1 = hex_to_bytecode(@expected_witness_1_hex);
+    let expected_witness_2_hex =
+        "0xaa20a23421f2ba909c885a3077bb6f8eb4312487797693bbcfe7e311f797e3c5b8fa87";
+    let expected_witness_2 = hex_to_bytecode(@expected_witness_2_hex);
+
+    assert_eq!(input0.previous_outpoint.vout, @0, "Outpoint vout on input 1 is not correct");
+    assert_eq!(
+        input0.previous_outpoint.txid,
+        @u256_from_byte_array_with_offset(@expected_txid, 0, 32),
+        "Outpoint txid on input 1 is not correct"
+    );
+    assert_eq!(input0.signature_script.len(), 0, "Script sig on input 1 is not empty");
+    assert_eq!(input0.witness.len(), 2, "Witness length on input 1 is not correct");
+    assert_eq!(input0.witness[0], @expected_witness_1, "Witness 1 on input 1 is not correct");
+    assert_eq!(input0.witness[1], @expected_witness_2, "Witness 2 on input 1 is not correct");
+    assert_eq!(input0.sequence, @0xFFFFFFFF, "Sequence on input 1 is not correct");
+
+    let output0 = transaction.transaction_outputs[0];
+    assert_eq!(output0.value, @20000, "Output 1 value is not correct");
+    let expected_pk_script_hex = "0x76a914ee63c8c790952de677d1f8019c9474d84098d6e188ac";
+    let expected_pk_script = hex_to_bytecode(@expected_pk_script_hex);
+    assert_eq!(output0.publickey_script, @expected_pk_script, "Output 1 pk_script is not correct");
+
+    assert_eq!(transaction.locktime, 0, "Lock time is not correct");
+}
+
 #[test]
 fn test_deserialize_coinbase_transaction() { // TODO
 }