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trezor-firmware/core/src/apps/ripple/serialize.py

128 lines
4.3 KiB
Python

# Serializes into the Ripple Format
#
# Inspired by https://github.com/miracle2k/ripple-python and https://github.com/ripple/ripple-lib
# Docs at https://wiki.ripple.com/Binary_Format and https://developers.ripple.com/transaction-common-fields.html
#
# The first four bits specify the field type (int16, int32, account..)
# the other four the record type (amount, fee, destination..) and then
# the actual data follow. This currently only supports the Payment
# transaction type and the fields that are required for it.
from trezor.messages import RippleSignTx
from . import helpers
FIELD_TYPE_INT16 = 1
FIELD_TYPE_INT32 = 2
FIELD_TYPE_AMOUNT = 6
FIELD_TYPE_VL = 7
FIELD_TYPE_ACCOUNT = 8
FIELDS_MAP = {
"account": {"type": FIELD_TYPE_ACCOUNT, "key": 1},
"amount": {"type": FIELD_TYPE_AMOUNT, "key": 1},
"destination": {"type": FIELD_TYPE_ACCOUNT, "key": 3},
"fee": {"type": FIELD_TYPE_AMOUNT, "key": 8},
"sequence": {"type": FIELD_TYPE_INT32, "key": 4},
"type": {"type": FIELD_TYPE_INT16, "key": 2},
"signingPubKey": {"type": FIELD_TYPE_VL, "key": 3},
"flags": {"type": FIELD_TYPE_INT32, "key": 2},
"txnSignature": {"type": FIELD_TYPE_VL, "key": 4},
"lastLedgerSequence": {"type": FIELD_TYPE_INT32, "key": 27},
"destinationTag": {"type": FIELD_TYPE_INT32, "key": 14},
}
TRANSACTION_TYPES = {"Payment": 0}
def serialize(msg: RippleSignTx, source_address: str, pubkey=None, signature=None):
w = bytearray()
# must be sorted numerically first by type and then by name
write(w, FIELDS_MAP["type"], TRANSACTION_TYPES["Payment"])
write(w, FIELDS_MAP["flags"], msg.flags)
write(w, FIELDS_MAP["sequence"], msg.sequence)
write(w, FIELDS_MAP["destinationTag"], msg.payment.destination_tag)
write(w, FIELDS_MAP["lastLedgerSequence"], msg.last_ledger_sequence)
write(w, FIELDS_MAP["amount"], msg.payment.amount)
write(w, FIELDS_MAP["fee"], msg.fee)
write(w, FIELDS_MAP["signingPubKey"], pubkey)
write(w, FIELDS_MAP["txnSignature"], signature)
write(w, FIELDS_MAP["account"], source_address)
write(w, FIELDS_MAP["destination"], msg.payment.destination)
return w
def write(w: bytearray, field: dict, value):
if value is None:
return
write_type(w, field)
if field["type"] == FIELD_TYPE_INT16:
w.extend(value.to_bytes(2, "big"))
elif field["type"] == FIELD_TYPE_INT32:
w.extend(value.to_bytes(4, "big"))
elif field["type"] == FIELD_TYPE_AMOUNT:
w.extend(serialize_amount(value))
elif field["type"] == FIELD_TYPE_ACCOUNT:
write_bytes_varint(w, helpers.decode_address(value))
elif field["type"] == FIELD_TYPE_VL:
write_bytes_varint(w, value)
else:
raise ValueError("Unknown field type")
def write_type(w: bytearray, field: dict):
if field["key"] <= 0xF:
w.append((field["type"] << 4) | field["key"])
else:
# this concerns two-bytes fields such as lastLedgerSequence
w.append(field["type"] << 4)
w.append(field["key"])
def serialize_amount(value: int) -> bytearray:
if value < 0:
raise ValueError("Only non-negative integers are supported")
if value > helpers.MAX_ALLOWED_AMOUNT:
raise ValueError("Value is too large")
b = bytearray(value.to_bytes(8, "big"))
b[0] &= 0x7F # clear first bit to indicate XRP
b[0] |= 0x40 # set second bit to indicate positive number
return b
def write_bytes_varint(w: bytearray, value: bytes):
"""Serialize a variable length bytes."""
write_varint(w, len(value))
w.extend(value)
def write_varint(w: bytearray, val: int):
"""
Implements variable-length int encoding from Ripple.
See: https://ripple.com/wiki/Binary_Format#Variable_Length_Data_Encoding
"""
if val < 0:
raise ValueError("Only non-negative integers are supported")
elif val < 192:
w.append(val)
elif val <= 12480:
val -= 193
w.append(193 + rshift(val, 8))
w.append(val & 0xFF)
elif val <= 918744:
val -= 12481
w.append(241 + rshift(val, 16))
w.append(rshift(val, 8) & 0xFF)
w.append(val & 0xFF)
else:
raise ValueError("Value is too large")
def rshift(val, n):
"""
Implements signed right-shift.
See: http://stackoverflow.com/a/5833119/15677
"""
return (val % 0x1_0000_0000) >> n