New util functions in python client

- recover_message / recover_transaction
- get_selector_from_data

client/src/ledger_app_clients/ethereum/utils.py

@@ -0,0 +1,41 @@
+from eth_account import Account
+from eth_account.messages import encode_defunct, encode_typed_data
+import rlp
+
+
+def get_selector_from_data(data: str) -> bytes:
+    raw_data = bytes.fromhex(data[2:])
+    return raw_data[:4]
+
+
+def recover_message(msg, vrs: tuple) -> bytes:
+    if isinstance(msg, dict):  # EIP-712
+        smsg = encode_typed_data(full_message=msg)
+    else:  # EIP-191
+        smsg = encode_defunct(primitive=msg)
+    addr = Account.recover_message(smsg, vrs)
+    return bytes.fromhex(addr[2:])
+
+
+# TODO: Figure out why it doesn't work for non-legacy transactions
+def recover_transaction(tx_params, vrs: tuple) -> bytes:
+    raw_tx = Account.create().sign_transaction(tx_params).rawTransaction
+    prefix = bytes()
+    if raw_tx[0] in [0x01, 0x02]:
+        prefix = raw_tx[:1]
+        raw_tx = raw_tx[len(prefix):]
+    if prefix == bytes():
+        # v is returned on one byte only so it might have overflowed
+        # in that case, we will reconstruct it to its full value
+        if "chainId" in tx_params:
+            trunc_chain_id = tx_params["chainId"]
+            while trunc_chain_id.bit_length() > 32:
+                trunc_chain_id >>= 8
+            target = tx_params["chainId"] * 2 + 35
+            trunc_target = trunc_chain_id * 2 + 35
+            diff = vrs[0][0] - (trunc_target & 0xff)
+            vrs = (target + diff, vrs[1], vrs[2])
+    decoded = rlp.decode(raw_tx)
+    reencoded = rlp.encode(decoded[:-3] + list(vrs))
+    addr = Account.recover_transaction(prefix + reencoded)
+    return bytes.fromhex(addr[2:])