十三、隔离见证（1+13隔离政策）

tx.py

from io import BytesIO
from unittest import TestCase

import json
import requests

from ecc import PrivateKey
from helper import (
    encode_varint,
    hash256,
    int_to_little_endian,
    little_endian_to_int,
    read_varint,
    SIGHASH_ALL,
)
from script import p2pkh_script, Script


class TxFetcher:
    cache = {}
    
    @classmethod
    def get_url(cls, testnet=False):
        if testnet:
            return 'https://blockstream.info/testnet/api'
        else:
            return 'https://blockstream.info/api'

    @classmethod
    def fetch(cls, tx_id, testnet=False, fresh=False):
        if fresh or (tx_id not in cls.cache):
            url = '{}/tx/{}/hex'.format(cls.get_url(testnet), tx_id)
            response = requests.get(url)
            try:
                raw = bytes.fromhex(response.text.strip())
            except ValueError:
                raise ValueError('unexpected response: {}'.format(response.text))
            tx = Tx.parse(BytesIO(raw), testnet=testnet)
            # make sure the tx we got matches to the hash we requested
            if tx.segwit:
                computed = tx.id()
            else:
                computed = hash256(raw)[::-1].hex()
            if computed != tx_id:
                raise RuntimeError('server lied: {} vs {}'.format(computed, tx_id))
            cls.cache[tx_id] = tx
        cls.cache[tx_id].testnet = testnet
        return cls.cache[tx_id]

    @classmethod
    def load_cache(cls, filename):
        disk_cache = json.loads(open(filename, 'r').read())
        for k, raw_hex in disk_cache.items():
            cls.cache[k] = Tx.parse(BytesIO(bytes.fromhex(raw_hex)))

    @classmethod
    def dump_cache(cls, filename):
        with open(filename, 'w') as f:
            to_dump = {k: tx.serialize().hex() for k, tx in cls.cache.items()}
            s = json.dumps(to_dump, sort_keys=True, indent=4)
            f.write(s)


# tag::source1[]
class Tx:
    command = b'tx'

    def __init__(self, version, tx_ins, tx_outs, 
        locktime, testnet=False, segwit=False):
        self.version = version
        self.tx_ins = tx_ins
        self.tx_outs = tx_outs
        self.locktime = locktime
        self.testnet = testnet
        self.segwit = segwit
        self._hash_prevouts = None
        self._hash_sequence = None
        self._hash_outputs = None
    # end::source1[]

    def __repr__(self):
        tx_ins = ''
        for tx_in in self.tx_ins:
            tx_ins += tx_in.__repr__() + '\n'
        tx_outs = ''
        for tx_out in self.tx_outs:
            tx_outs += tx_out.__repr__() + '\n'
        return 'tx: {}\nversion: {}\ntx_ins:\n{}tx_outs:\n{}locktime: {}'.format(
            self.id(),
            self.version,
            tx_ins,
            tx_outs,
            self.locktime,
        )

    def id(self):
        '''Human-readable hexadecimal of the transaction hash'''
        return self.hash().hex()

    # tag::source5[]
    def hash(self):
        '''Binary hash of the legacy serialization'''
        return hash256(self.serialize_legacy())[::-1]
    # end::source5[]

    # tag::source2[]
    @classmethod
    def parse(cls, s, testnet=False):
        s.read(4)  # <1>
        if s.read(1) == b'\x00':  # <2>
            parse_method = cls.parse_segwit
        else:
            parse_method = cls.parse_legacy
        s.seek(-5, 1)  # <3>
        return parse_method(s, testnet=testnet)

    @classmethod
    def parse_legacy(cls, s, testnet=False):
        version = little_endian_to_int(s.read(4))   # <4>
        num_inputs = read_varint(s)
        inputs = []
        for _ in range(num_inputs):
            inputs.append(TxIn.parse(s))
        num_outputs = read_varint(s)
        outputs = []
        for _ in range(num_outputs):
            outputs.append(TxOut.parse(s))
        locktime = little_endian_to_int(s.read(4))
        return cls(version, inputs, outputs, locktime, 
                   testnet=testnet, segwit=False)
    # end::source2[]

    # tag::source3[]
    @classmethod
    def parse_segwit(cls, s, testnet=False):
        version = little_endian_to_int(s.read(4))
        marker = s.read(2)
        if marker != b'\x00\x01':  # <1>
            raise RuntimeError('Not a segwit transaction {}'.format(marker))
        num_inputs = read_varint(s)
        inputs = []
        for _ in range(num_inputs):
            inputs.append(TxIn.parse(s))
        num_outputs = read_varint(s)
        outputs = []
        for _ in range(num_outputs):
            outputs.append(TxOut.parse(s))
        for tx_in in inputs:  # <2>
            num_items = read_varint(s)
            items = []
            for _ in range(num_items):
                item_len = read_varint(s)
                if item_len == 0:
                    items.append(0)
                else:
                    items.append(s.read(item_len))
            tx_in.witness = items
        locktime = little_endian_to_int(s.read(4))
        return cls(version, inputs, outputs, locktime, 
                   testnet=testnet, segwit=True)
    # end::source3[]

    # tag::source4[]
    def serialize(self):
        if self.segwit:
            return self.serialize_segwit()
        else:
            return self.serialize_legacy()

    def serialize_legacy(self):  # <1>
        result = int_to_little_endian(self.version, 4)
        result += encode_varint(len(self.tx_ins))
        for tx_in in self.tx_ins:
            result += tx_in.serialize()
        result += encode_varint(len(self.tx_outs))
        for tx_out in self.tx_outs:
            result += tx_out.serialize()
        result += int_to_little_endian(self.locktime, 4)
        return result

    def serialize_segwit(self):
        result = int_to_little_endian(self.version, 4)
        result += b'\x00\x01'  # <2>
        result += encode_varint(len(self.tx_ins))
        for tx_in in self.tx_ins:
            result += tx_in.serialize()
        result += encode_varint(len(self.tx_outs))
        for tx_out in self.tx_outs:
            result += tx_out.serialize()
        for tx_in in self.tx_ins:  # <3>
            result += int_to_little_endian(len(tx_in.witness), 1)
            for item in tx_in.witness:
                if type(item) == int:
                    result += int_to_little_endian(item, 1)
                else:
                    result += encode_varint(len(item)) + item
        result += int_to_little_endian(self.locktime, 4)
        return result
    # end::source4[]

    def fee(self):
        '''Returns the fee of this transaction in satoshi'''
        # initialize input sum and output sum
        input_sum, output_sum = 0, 0
        # use TxIn.value() to sum up the input amounts
        for tx_in in self.tx_ins:
            input_sum += tx_in.value(self.testnet)
        # use TxOut.amount to sum up the output amounts
        for tx_out in self.tx_outs:
            output_sum += tx_out.amount
        # fee is input sum - output sum
        return input_sum - output_sum

    def sig_hash(self, input_index, redeem_script=None):
        '''Returns the integer representation of the hash that needs to get
        signed for index input_index'''
        # start the serialization with version
        # use int_to_little_endian in 4 bytes
        s = int_to_little_endian(self.version, 4)
        # add how many inputs there are using encode_varint
        s += encode_varint(len(self.tx_ins))
        # loop through each input using enumerate, so we have the input index
        for i, tx_in in enumerate(self.tx_ins):
            # if the input index is the one we're signing
            if i == input_index:
                # if the RedeemScript was passed in, that's the ScriptSig
                if redeem_script:
                    script_sig = redeem_script
                # otherwise the previous tx's ScriptPubkey is the ScriptSig
                else:
                    script_sig = tx_in.script_pubkey(self.testnet)
            # Otherwise, the ScriptSig is empty
            else:
                script_sig = None
            # add the serialization of the input with the ScriptSig we want
            s += TxIn(
                prev_tx=tx_in.prev_tx,
                prev_index=tx_in.prev_index,
                script_sig=script_sig,
                sequence=tx_in.sequence,
            ).serialize()
        # add how many outputs there are using encode_varint
        s += encode_varint(len(self.tx_outs))
        # add the serialization of each output
        for tx_out in self.tx_outs:
            s += tx_out.serialize()
        # add the locktime using int_to_little_endian in 4 bytes
        s += int_to_little_endian(self.locktime, 4)
        # add SIGHASH_ALL using int_to_little_endian in 4 bytes
        s += int_to_little_endian(SIGHASH_ALL, 4)
        # hash256 the serialization
        h256 = hash256(s)
        # convert the result to an integer using int.from_bytes(x, 'big')
        return int.from_bytes(h256, 'big')

    def hash_prevouts(self):
        if self._hash_prevouts is None:
            all_prevouts = b''
            all_sequence = b''
            for tx_in in self.tx_ins:
                all_prevouts += tx_in.prev_tx[::-1] + int_to_little_endian(tx_in.prev_index, 4)
                all_sequence += int_to_little_endian(tx_in.sequence, 4)
            self._hash_prevouts = hash256(all_prevouts)
            self._hash_sequence = hash256(all_sequence)
        return self._hash_prevouts

    def hash_sequence(self):
        if self._hash_sequence is None:
            self.hash_prevouts()  # this should calculate self._hash_prevouts
        return self._hash_sequence

    def hash_outputs(self):
        if self._hash_outputs is None:
            all_outputs = b''
            for tx_out in self.tx_outs:
                all_outputs += tx_out.serialize()
            self._hash_outputs = hash256(all_outputs)
        return self._hash_outputs

    def sig_hash_bip143(self, input_index, redeem_script=None, witness_script=None):
        '''Returns the integer representation of the hash that needs to get
        signed for index input_index'''
        tx_in = self.tx_ins[input_index]
        # per BIP143 spec
        s = int_to_little_endian(self.version, 4)
        s += self.hash_prevouts() + self.hash_sequence()
        s += tx_in.prev_tx[::-1] + int_to_little_endian(tx_in.prev_index, 4)
        if witness_script:
            script_code = witness_script.serialize()
        elif redeem_script:
            script_code = p2pkh_script(redeem_script.cmds[1]).serialize()
        else:
            script_code = p2pkh_script(tx_in.script_pubkey(self.testnet).cmds[1]).serialize()
        s += script_code
        s += int_to_little_endian(tx_in.value(), 8)
        s += int_to_little_endian(tx_in.sequence, 4)
        s += self.hash_outputs()
        s += int_to_little_endian(self.locktime, 4)
        s += int_to_little_endian(SIGHASH_ALL, 4)
        return int.from_bytes(hash256(s), 'big')

    def verify_input(self, input_index):
        '''Returns whether the input has a valid signature'''
        # get the relevant input
        tx_in = self.tx_ins[input_index]
        # grab the previous ScriptPubKey
        script_pubkey = tx_in.script_pubkey(testnet=self.testnet)
        # check to see if the ScriptPubkey is a p2sh
        if script_pubkey.is_p2sh_script_pubkey():
            # the last cmd has to be the RedeemScript to trigger
            cmd = tx_in.script_sig.cmds[-1]
            # parse the RedeemScript
            raw_redeem = int_to_little_endian(len(cmd), 1) + cmd
            redeem_script = Script.parse(BytesIO(raw_redeem))
            # the RedeemScript might be p2wpkh or p2wsh
            if redeem_script.is_p2wpkh_script_pubkey():
                z = self.sig_hash_bip143(input_index, redeem_script)
                witness = tx_in.witness
            elif redeem_script.is_p2wsh_script_pubkey():
                cmd = tx_in.witness[-1]
                raw_witness = encode_varint(len(cmd)) + cmd
                witness_script = Script.parse(BytesIO(raw_witness))
                z = self.sig_hash_bip143(input_index, witness_script=witness_script)
                witness = tx_in.witness
            else:
                z = self.sig_hash(input_index, redeem_script)
                witness = None
        else:
            # ScriptPubkey might be a p2wpkh or p2wsh
            if script_pubkey.is_p2wpkh_script_pubkey():
                z = self.sig_hash_bip143(input_index)
                witness = tx_in.witness
            elif script_pubkey.is_p2wsh_script_pubkey():
                cmd = tx_in.witness[-1]
                raw_witness = encode_varint(len(cmd)) + cmd
                witness_script = Script.parse(BytesIO(raw_witness))
                z = self.sig_hash_bip143(input_index, witness_script=witness_script)
                witness = tx_in.witness
            else:
                z = self.sig_hash(input_index)
                witness = None
        # combine the current ScriptSig and the previous ScriptPubKey
        combined = tx_in.script_sig + script_pubkey
        # evaluate the combined script
        return combined.evaluate(z, witness)

    def verify(self):
        '''Verify this transaction'''
        # check that we're not creating money
        if self.fee() < 0:
            return False
        # check that each input has a valid ScriptSig
        for i in range(len(self.tx_ins)):
            if not self.verify_input(i):
                return False
        return True

    def sign_input(self, input_index, private_key):
        '''Signs the input using the private key'''
        # get the signature hash (z)
        z = self.sig_hash(input_index)
        # get der signature of z from private key
        der = private_key.sign(z).der()
        # append the SIGHASH_ALL to der (use SIGHASH_ALL.to_bytes(1, 'big'))
        sig = der + SIGHASH_ALL.to_bytes(1, 'big')
        # calculate the sec
        sec = private_key.point.sec()
        # initialize a new script with [sig, sec] as the cmds
        script_sig = Script([sig, sec])
        # change input's script_sig to new script
        self.tx_ins[input_index].script_sig = script_sig
        # return whether sig is valid using self.verify_input
        return self.verify_input(input_index)

    def is_coinbase(self):
        '''Returns whether this transaction is a coinbase transaction or not'''
        # check that there is exactly 1 input
        if len(self.tx_ins) != 1:
            return False
        # grab the first input
        first_input = self.tx_ins[0]
        # check that first input prev_tx is b'\x00' * 32 bytes
        if first_input.prev_tx != b'\x00' * 32:
            return False
        # check that first input prev_index is 0xffffffff
        if first_input.prev_index != 0xffffffff:
            return False
        return True

    def coinbase_height(self):
        '''Returns the height of the block this coinbase transaction is in
        Returns None if this transaction is not a coinbase transaction
        '''
        # if this is NOT a coinbase transaction, return None
        if not self.is_coinbase():
            return None
        # grab the first cmd
        first_cmd = self.tx_ins[0].script_sig.cmds[0]
        # convert the cmd from little endian to int
        return little_endian_to_int(first_cmd)


class TxIn:

    def __init__(self, prev_tx, prev_index, script_sig=None, sequence=0xffffffff):
        self.prev_tx = prev_tx
        self.prev_index = prev_index
        if script_sig is None:
            self.script_sig = Script()
        else:
            self.script_sig = script_sig
        self.sequence = sequence

    def __repr__(self):
        return '{}:{}'.format(
            self.prev_tx.hex(),
            self.prev_index,
        )

    @classmethod
    def parse(cls, s):
        '''Takes a byte stream and parses the tx_input at the start
        return a TxIn object
        '''
        # prev_tx is 32 bytes, little endian
        prev_tx = s.read(32)[::-1]
        # prev_index is an integer in 4 bytes, little endian
        prev_index = little_endian_to_int(s.read(4))
        # use Script.parse to get the ScriptSig
        script_sig = Script.parse(s)
        # sequence is an integer in 4 bytes, little-endian
        sequence = little_endian_to_int(s.read(4))
        # return an instance of the class (see __init__ for args)
        return cls(prev_tx, prev_index, script_sig, sequence)

    def serialize(self):
        '''Returns the byte serialization of the transaction input'''
        # serialize prev_tx, little endian
        result = self.prev_tx[::-1]
        # serialize prev_index, 4 bytes, little endian
        result += int_to_little_endian(self.prev_index, 4)
        # serialize the script_sig
        result += self.script_sig.serialize()
        # serialize sequence, 4 bytes, little endian
        result += int_to_little_endian(self.sequence, 4)
        return result

    def fetch_tx(self, testnet=False):
        return TxFetcher.fetch(self.prev_tx.hex(), testnet=testnet)

    def value(self, testnet=False):
        '''Get the outpoint value by looking up the tx hash
        Returns the amount in satoshi
        '''
        # use self.fetch_tx to get the transaction
        tx = self.fetch_tx(testnet=testnet)
        # get the output at self.prev_index
        # return the amount property
        return tx.tx_outs[self.prev_index].amount

    def script_pubkey(self, testnet=False):
        '''Get the ScriptPubKey by looking up the tx hash
        Returns a Script object
        '''
        # use self.fetch_tx to get the transaction
        tx = self.fetch_tx(testnet=testnet)
        # get the output at self.prev_index
        # return the script_pubkey property
        return tx.tx_outs[self.prev_index].script_pubkey


class TxOut:

    def __init__(self, amount, script_pubkey):
        self.amount = amount
        self.script_pubkey = script_pubkey

    def __repr__(self):
        return '{}:{}'.format(self.amount, self.script_pubkey)

    @classmethod
    def parse(cls, s):
        '''Takes a byte stream and parses the tx_output at the start
        return a TxOut object
        '''
        # amount is an integer in 8 bytes, little endian
        amount = little_endian_to_int(s.read(8))
        # use Script.parse to get the ScriptPubKey
        script_pubkey = Script.parse(s)
        # return an instance of the class (see __init__ for args)
        return cls(amount, script_pubkey)

    def serialize(self):
        '''Returns the byte serialization of the transaction output'''
        # serialize amount, 8 bytes, little endian
        result = int_to_little_endian(self.amount, 8)
        # serialize the script_pubkey
        result += self.script_pubkey.serialize()
        return result


class TxTest(TestCase):
    cache_file = '../tx.cache'

    @classmethod
    def setUpClass(cls):
        # fill with cache so we don't have to be online to run these tests
        TxFetcher.load_cache(cls.cache_file)

    @classmethod
    def tearDownClass(cls):
        # write the cache to disk
        TxFetcher.dump_cache(cls.cache_file)

    def test_parse_version(self):
        raw_tx = bytes.fromhex('0100000001813f79011acb80925dfe69b3def355fe914bd1d96a3f5f71bf8303c6a989c7d1000000006b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278afeffffff02a135ef01000000001976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac99c39800000000001976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac19430600')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(tx.version, 1)

    def test_parse_inputs(self):
        raw_tx = bytes.fromhex('0100000001813f79011acb80925dfe69b3def355fe914bd1d96a3f5f71bf8303c6a989c7d1000000006b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278afeffffff02a135ef01000000001976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac99c39800000000001976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac19430600')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(len(tx.tx_ins), 1)
        want = bytes.fromhex('d1c789a9c60383bf715f3f6ad9d14b91fe55f3deb369fe5d9280cb1a01793f81')
        self.assertEqual(tx.tx_ins[0].prev_tx, want)
        self.assertEqual(tx.tx_ins[0].prev_index, 0)
        want = bytes.fromhex('6b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278a')
        self.assertEqual(tx.tx_ins[0].script_sig.serialize(), want)
        self.assertEqual(tx.tx_ins[0].sequence, 0xfffffffe)

    def test_parse_outputs(self):
        raw_tx = bytes.fromhex('0100000001813f79011acb80925dfe69b3def355fe914bd1d96a3f5f71bf8303c6a989c7d1000000006b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278afeffffff02a135ef01000000001976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac99c39800000000001976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac19430600')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(len(tx.tx_outs), 2)
        want = 32454049
        self.assertEqual(tx.tx_outs[0].amount, want)
        want = bytes.fromhex('1976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac')
        self.assertEqual(tx.tx_outs[0].script_pubkey.serialize(), want)
        want = 10011545
        self.assertEqual(tx.tx_outs[1].amount, want)
        want = bytes.fromhex('1976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac')
        self.assertEqual(tx.tx_outs[1].script_pubkey.serialize(), want)

    def test_parse_locktime(self):
        raw_tx = bytes.fromhex('0100000001813f79011acb80925dfe69b3def355fe914bd1d96a3f5f71bf8303c6a989c7d1000000006b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278afeffffff02a135ef01000000001976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac99c39800000000001976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac19430600')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(tx.locktime, 410393)

    def test_serialize(self):
        raw_tx = bytes.fromhex('0100000001813f79011acb80925dfe69b3def355fe914bd1d96a3f5f71bf8303c6a989c7d1000000006b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278afeffffff02a135ef01000000001976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac99c39800000000001976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac19430600')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(tx.serialize(), raw_tx)

    def test_input_value(self):
        tx_hash = 'd1c789a9c60383bf715f3f6ad9d14b91fe55f3deb369fe5d9280cb1a01793f81'
        index = 0
        want = 42505594
        tx_in = TxIn(bytes.fromhex(tx_hash), index)
        self.assertEqual(tx_in.value(), want)

    def test_input_pubkey(self):
        tx_hash = 'd1c789a9c60383bf715f3f6ad9d14b91fe55f3deb369fe5d9280cb1a01793f81'
        index = 0
        tx_in = TxIn(bytes.fromhex(tx_hash), index)
        want = bytes.fromhex('1976a914a802fc56c704ce87c42d7c92eb75e7896bdc41ae88ac')
        self.assertEqual(tx_in.script_pubkey().serialize(), want)

    def test_fee(self):
        raw_tx = bytes.fromhex('0100000001813f79011acb80925dfe69b3def355fe914bd1d96a3f5f71bf8303c6a989c7d1000000006b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278afeffffff02a135ef01000000001976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac99c39800000000001976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac19430600')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(tx.fee(), 40000)
        raw_tx = bytes.fromhex('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')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(tx.fee(), 140500)

    def test_sig_hash(self):
        tx = TxFetcher.fetch('452c629d67e41baec3ac6f04fe744b4b9617f8f859c63b3002f8684e7a4fee03')
        want = int('27e0c5994dec7824e56dec6b2fcb342eb7cdb0d0957c2fce9882f715e85d81a6', 16)
        self.assertEqual(tx.sig_hash(0), want)

    def test_verify_p2pkh(self):
        tx = TxFetcher.fetch('452c629d67e41baec3ac6f04fe744b4b9617f8f859c63b3002f8684e7a4fee03')
        self.assertTrue(tx.verify())
        tx = TxFetcher.fetch('5418099cc755cb9dd3ebc6cf1a7888ad53a1a3beb5a025bce89eb1bf7f1650a2', testnet=True)
        self.assertTrue(tx.verify())

    def test_verify_p2sh(self):
        tx = TxFetcher.fetch('46df1a9484d0a81d03ce0ee543ab6e1a23ed06175c104a178268fad381216c2b')
        self.assertTrue(tx.verify())

    def test_verify_p2wpkh(self):
        tx = TxFetcher.fetch('d869f854e1f8788bcff294cc83b280942a8c728de71eb709a2c29d10bfe21b7c', testnet=True)
        self.assertTrue(tx.verify())

    def test_verify_p2sh_p2wpkh(self):
        tx = TxFetcher.fetch('c586389e5e4b3acb9d6c8be1c19ae8ab2795397633176f5a6442a261bbdefc3a')
        self.assertTrue(tx.verify())

    def test_verify_p2wsh(self):
        tx = TxFetcher.fetch('78457666f82c28aa37b74b506745a7c7684dc7842a52a457b09f09446721e11c', testnet=True)
        self.assertTrue(tx.verify())

    def test_verify_p2sh_p2wsh(self):
        tx = TxFetcher.fetch('954f43dbb30ad8024981c07d1f5eb6c9fd461e2cf1760dd1283f052af746fc88', testnet=True)
        self.assertTrue(tx.verify())

    def test_sign_input(self):
        private_key = PrivateKey(secret=8675309)
        stream = BytesIO(bytes.fromhex('010000000199a24308080ab26e6fb65c4eccfadf76749bb5bfa8cb08f291320b3c21e56f0d0d00000000ffffffff02408af701000000001976a914d52ad7ca9b3d096a38e752c2018e6fbc40cdf26f88ac80969800000000001976a914507b27411ccf7f16f10297de6cef3f291623eddf88ac00000000'))
        tx_obj = Tx.parse(stream, testnet=True)
        self.assertTrue(tx_obj.sign_input(0, private_key))
        want = '010000000199a24308080ab26e6fb65c4eccfadf76749bb5bfa8cb08f291320b3c21e56f0d0d0000006b4830450221008ed46aa2cf12d6d81065bfabe903670165b538f65ee9a3385e6327d80c66d3b502203124f804410527497329ec4715e18558082d489b218677bd029e7fa306a72236012103935581e52c354cd2f484fe8ed83af7a3097005b2f9c60bff71d35bd795f54b67ffffffff02408af701000000001976a914d52ad7ca9b3d096a38e752c2018e6fbc40cdf26f88ac80969800000000001976a914507b27411ccf7f16f10297de6cef3f291623eddf88ac00000000'
        self.assertEqual(tx_obj.serialize().hex(), want)

    def test_is_coinbase(self):
        raw_tx = bytes.fromhex('01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff5e03d71b07254d696e656420627920416e74506f6f6c20626a31312f4542312f4144362f43205914293101fabe6d6d678e2c8c34afc36896e7d9402824ed38e856676ee94bfdb0c6c4bcd8b2e5666a0400000000000000c7270000a5e00e00ffffffff01faf20b58000000001976a914338c84849423992471bffb1a54a8d9b1d69dc28a88ac00000000')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertTrue(tx.is_coinbase())

    def test_coinbase_height(self):
        raw_tx = bytes.fromhex('01000000010000000000000000000000000000000000000000000000000000000000000000ffffffff5e03d71b07254d696e656420627920416e74506f6f6c20626a31312f4542312f4144362f43205914293101fabe6d6d678e2c8c34afc36896e7d9402824ed38e856676ee94bfdb0c6c4bcd8b2e5666a0400000000000000c7270000a5e00e00ffffffff01faf20b58000000001976a914338c84849423992471bffb1a54a8d9b1d69dc28a88ac00000000')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertEqual(tx.coinbase_height(), 465879)
        raw_tx = bytes.fromhex('0100000001813f79011acb80925dfe69b3def355fe914bd1d96a3f5f71bf8303c6a989c7d1000000006b483045022100ed81ff192e75a3fd2304004dcadb746fa5e24c5031ccfcf21320b0277457c98f02207a986d955c6e0cb35d446a89d3f56100f4d7f67801c31967743a9c8e10615bed01210349fc4e631e3624a545de3f89f5d8684c7b8138bd94bdd531d2e213bf016b278afeffffff02a135ef01000000001976a914bc3b654dca7e56b04dca18f2566cdaf02e8d9ada88ac99c39800000000001976a9141c4bc762dd5423e332166702cb75f40df79fea1288ac19430600')
        stream = BytesIO(raw_tx)
        tx = Tx.parse(stream)
        self.assertIsNone(tx.coinbase_height())