forked from trezor/blockbook
/
erc20.go
219 lines (206 loc) · 8.37 KB
/
erc20.go
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package eth
import (
"blockbook/bchain"
"context"
"encoding/hex"
"math/big"
"strings"
"sync"
ethcommon "github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/golang/glog"
"github.com/juju/errors"
)
var erc20abi = `[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function","signature":"0x06fdde03"},
{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function","signature":"0x95d89b41"},
{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"payable":false,"type":"function","signature":"0x313ce567"},
{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"type":"function","signature":"0x18160ddd"},
{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"payable":false,"type":"function","signature":"0x70a08231"},
{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"payable":false,"type":"function","signature":"0xa9059cbb"},
{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"payable":false,"type":"function","signature":"0x23b872dd"},
{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"payable":false,"type":"function","signature":"0x095ea7b3"},
{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"payable":false,"type":"function","signature":"0xdd62ed3e"},
{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Transfer","type":"event","signature":"0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"},
{"anonymous":false,"inputs":[{"indexed":true,"name":"_owner","type":"address"},{"indexed":true,"name":"_spender","type":"address"},{"indexed":false,"name":"_value","type":"uint256"}],"name":"Approval","type":"event","signature":"0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925"},
{"inputs":[{"name":"_initialAmount","type":"uint256"},{"name":"_tokenName","type":"string"},{"name":"_decimalUnits","type":"uint8"},{"name":"_tokenSymbol","type":"string"}],"payable":false,"type":"constructor"},
{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_value","type":"uint256"},{"name":"_extraData","type":"bytes"}],"name":"approveAndCall","outputs":[{"name":"success","type":"bool"}],"payable":false,"type":"function","signature":"0xcae9ca51"},
{"constant":true,"inputs":[],"name":"version","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function","signature":"0x54fd4d50"}]`
// doing the parsing/processing without using go-ethereum/accounts/abi library, it is simple to get data from Transfer event
const erc20TransferMethodSignature = "0xa9059cbb"
const erc20TransferEventSignature = "0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef"
const erc20NameSignature = "0x06fdde03"
const erc20SymbolSignature = "0x95d89b41"
const erc20DecimalsSignature = "0x313ce567"
const erc20BalanceOf = "0x70a08231"
var cachedContracts = make(map[string]*bchain.Erc20Contract)
var cachedContractsMux sync.Mutex
func addressFromPaddedHex(s string) (string, error) {
var t big.Int
var ok bool
if has0xPrefix(s) {
_, ok = t.SetString(s[2:], 16)
} else {
_, ok = t.SetString(s, 16)
}
if !ok {
return "", errors.New("Data is not a number")
}
a := ethcommon.BigToAddress(&t)
return a.String(), nil
}
func erc20GetTransfersFromLog(logs []*rpcLog) ([]bchain.Erc20Transfer, error) {
var r []bchain.Erc20Transfer
for _, l := range logs {
if len(l.Topics) == 3 && l.Topics[0] == erc20TransferEventSignature {
var t big.Int
_, ok := t.SetString(l.Data, 0)
if !ok {
return nil, errors.New("Data is not a number")
}
from, err := addressFromPaddedHex(l.Topics[1])
if err != nil {
return nil, err
}
to, err := addressFromPaddedHex(l.Topics[2])
if err != nil {
return nil, err
}
r = append(r, bchain.Erc20Transfer{
Contract: strings.ToLower(l.Address),
From: strings.ToLower(from),
To: strings.ToLower(to),
Tokens: t,
})
}
}
return r, nil
}
func erc20GetTransfersFromTx(tx *rpcTransaction) ([]bchain.Erc20Transfer, error) {
var r []bchain.Erc20Transfer
if len(tx.Payload) == 128+len(erc20TransferMethodSignature) && strings.HasPrefix(tx.Payload, erc20TransferMethodSignature) {
to, err := addressFromPaddedHex(tx.Payload[len(erc20TransferMethodSignature) : 64+len(erc20TransferMethodSignature)])
if err != nil {
return nil, err
}
var t big.Int
_, ok := t.SetString(tx.Payload[len(erc20TransferMethodSignature)+64:], 16)
if !ok {
return nil, errors.New("Data is not a number")
}
r = append(r, bchain.Erc20Transfer{
Contract: strings.ToLower(tx.To),
From: strings.ToLower(tx.From),
To: strings.ToLower(to),
Tokens: t,
})
}
return r, nil
}
func (b *EthereumRPC) ethCall(data, to string) (string, error) {
ctx, cancel := context.WithTimeout(context.Background(), b.timeout)
defer cancel()
var r string
err := b.rpc.CallContext(ctx, &r, "eth_call", map[string]interface{}{
"data": data,
"to": to,
}, "latest")
if err != nil {
return "", err
}
return r, nil
}
func parseErc20NumericProperty(contractDesc bchain.AddressDescriptor, data string) *big.Int {
if has0xPrefix(data) {
data = data[2:]
}
if len(data) == 64 {
var n big.Int
_, ok := n.SetString(data, 16)
if ok {
return &n
}
}
if glog.V(1) {
glog.Warning("Cannot parse '", data, "' for contract ", contractDesc)
}
return nil
}
func parseErc20StringProperty(contractDesc bchain.AddressDescriptor, data string) string {
if has0xPrefix(data) {
data = data[2:]
}
if len(data) > 128 {
n := parseErc20NumericProperty(contractDesc, data[64:128])
if n != nil {
l := n.Uint64()
if 2*int(l) <= len(data)-128 {
b, err := hex.DecodeString(data[128 : 128+2*l])
if err == nil {
return string(b)
}
}
}
}
if glog.V(1) {
glog.Warning("Cannot parse '", data, "' for contract ", contractDesc)
}
return ""
}
// EthereumTypeGetErc20ContractInfo returns information about ERC20 contract
func (b *EthereumRPC) EthereumTypeGetErc20ContractInfo(contractDesc bchain.AddressDescriptor) (*bchain.Erc20Contract, error) {
cds := string(contractDesc)
cachedContractsMux.Lock()
contract, found := cachedContracts[cds]
cachedContractsMux.Unlock()
if !found {
address := hexutil.Encode(contractDesc)
data, err := b.ethCall(erc20NameSignature, address)
if err != nil {
return nil, err
}
name := parseErc20StringProperty(contractDesc, data)
if name != "" {
data, err = b.ethCall(erc20SymbolSignature, address)
if err != nil {
return nil, err
}
symbol := parseErc20StringProperty(contractDesc, data)
data, err = b.ethCall(erc20DecimalsSignature, address)
if err != nil {
return nil, err
}
contract = &bchain.Erc20Contract{
Contract: address,
Name: name,
Symbol: symbol,
}
d := parseErc20NumericProperty(contractDesc, data)
if d != nil {
contract.Decimals = int(uint8(d.Uint64()))
} else {
contract.Decimals = EtherAmountDecimalPoint
}
} else {
contract = nil
}
cachedContractsMux.Lock()
cachedContracts[cds] = contract
cachedContractsMux.Unlock()
}
return contract, nil
}
// EthereumTypeGetErc20ContractBalance returns balance of ERC20 contract for given address
func (b *EthereumRPC) EthereumTypeGetErc20ContractBalance(addrDesc, contractDesc bchain.AddressDescriptor) (*big.Int, error) {
addr := hexutil.Encode(addrDesc)
contract := hexutil.Encode(contractDesc)
req := erc20BalanceOf + "0000000000000000000000000000000000000000000000000000000000000000"[len(addr)-2:] + addr[2:]
data, err := b.ethCall(req, contract)
if err != nil {
return nil, err
}
r := parseErc20NumericProperty(contractDesc, data)
if r == nil {
return nil, errors.New("Invalid balance")
}
return r, nil
}