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ante.go
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ante.go
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package auth
import (
"bytes"
"fmt"
sdk "github.com/cosmos/cosmos-sdk/types"
"github.com/spf13/viper"
)
const (
deductFeesCost sdk.Gas = 10
verifyCost = 100
)
// NewAnteHandler returns an AnteHandler that checks
// and increments sequence numbers, checks signatures & account numbers,
// and deducts fees from the first signer.
func NewAnteHandler(am AccountMapper, fck FeeCollectionKeeper) sdk.AnteHandler {
return func(
ctx sdk.Context, tx sdk.Tx,
) (_ sdk.Context, _ sdk.Result, abort bool) {
// This AnteHandler requires Txs to be StdTxs
stdTx, ok := tx.(StdTx)
if !ok {
return ctx, sdk.ErrInternal("tx must be StdTx").Result(), true
}
// Assert that there are signatures.
var sigs = stdTx.GetSignatures()
if len(sigs) == 0 {
return ctx,
sdk.ErrUnauthorized("no signers").Result(),
true
}
msg := tx.GetMsg()
// Assert that number of signatures is correct.
var signerAddrs = msg.GetSigners()
if len(sigs) != len(signerAddrs) {
return ctx,
sdk.ErrUnauthorized("wrong number of signers").Result(),
true
}
// Get the sign bytes (requires all account & sequence numbers and the fee)
sequences := make([]int64, len(signerAddrs))
for i := 0; i < len(signerAddrs); i++ {
sequences[i] = sigs[i].Sequence
}
accNums := make([]int64, len(signerAddrs))
for i := 0; i < len(signerAddrs); i++ {
accNums[i] = sigs[i].AccountNumber
}
fee := stdTx.Fee
chainID := ctx.ChainID()
// XXX: major hack; need to get ChainID
// into the app right away (#565)
if chainID == "" {
chainID = viper.GetString("chain-id")
}
signBytes := StdSignBytes(ctx.ChainID(), accNums, sequences, fee, msg)
// Check sig and nonce and collect signer accounts.
var signerAccs = make([]Account, len(signerAddrs))
for i := 0; i < len(sigs); i++ {
signerAddr, sig := signerAddrs[i], sigs[i]
// check signature, return account with incremented nonce
signerAcc, res := processSig(
ctx, am,
signerAddr, sig, signBytes,
)
if !res.IsOK() {
return ctx, res, true
}
// first sig pays the fees
if i == 0 {
// TODO: min fee
if !fee.Amount.IsZero() {
ctx.GasMeter().ConsumeGas(deductFeesCost, "deductFees")
signerAcc, res = deductFees(signerAcc, fee)
if !res.IsOK() {
return ctx, res, true
}
fck.addCollectedFees(ctx, fee.Amount)
}
}
// Save the account.
am.SetAccount(ctx, signerAcc)
signerAccs[i] = signerAcc
}
// cache the signer accounts in the context
ctx = WithSigners(ctx, signerAccs)
// set the gas meter
ctx = ctx.WithGasMeter(sdk.NewGasMeter(stdTx.Fee.Gas))
// TODO: tx tags (?)
return ctx, sdk.Result{}, false // continue...
}
}
// verify the signature and increment the sequence.
// if the account doesn't have a pubkey, set it.
func processSig(
ctx sdk.Context, am AccountMapper,
addr sdk.Address, sig StdSignature, signBytes []byte) (
acc Account, res sdk.Result) {
// Get the account.
acc = am.GetAccount(ctx, addr)
if acc == nil {
return nil, sdk.ErrUnknownAddress(addr.String()).Result()
}
// Check account number.
accnum := acc.GetAccountNumber()
if accnum != sig.AccountNumber {
return nil, sdk.ErrInvalidSequence(
fmt.Sprintf("Invalid account number. Got %d, expected %d", sig.AccountNumber, accnum)).Result()
}
// Check and increment sequence number.
seq := acc.GetSequence()
if seq != sig.Sequence {
return nil, sdk.ErrInvalidSequence(
fmt.Sprintf("Invalid sequence. Got %d, expected %d", sig.Sequence, seq)).Result()
}
acc.SetSequence(seq + 1)
// If pubkey is not known for account,
// set it from the StdSignature.
pubKey := acc.GetPubKey()
if pubKey == nil {
pubKey = sig.PubKey
if pubKey == nil {
return nil, sdk.ErrInvalidPubKey("PubKey not found").Result()
}
if !bytes.Equal(pubKey.Address(), addr) {
return nil, sdk.ErrInvalidPubKey(
fmt.Sprintf("PubKey does not match Signer address %v", addr)).Result()
}
err := acc.SetPubKey(pubKey)
if err != nil {
return nil, sdk.ErrInternal("setting PubKey on signer's account").Result()
}
}
// Check sig.
ctx.GasMeter().ConsumeGas(verifyCost, "ante verify")
if !pubKey.VerifyBytes(signBytes, sig.Signature) {
return nil, sdk.ErrUnauthorized("signature verification failed").Result()
}
return
}
// Deduct the fee from the account.
// We could use the CoinKeeper (in addition to the AccountMapper,
// because the CoinKeeper doesn't give us accounts), but it seems easier to do this.
func deductFees(acc Account, fee StdFee) (Account, sdk.Result) {
coins := acc.GetCoins()
feeAmount := fee.Amount
newCoins := coins.Minus(feeAmount)
if !newCoins.IsNotNegative() {
errMsg := fmt.Sprintf("%s < %s", coins, feeAmount)
return nil, sdk.ErrInsufficientFunds(errMsg).Result()
}
acc.SetCoins(newCoins)
return acc, sdk.Result{}
}
// BurnFeeHandler burns all fees (decreasing total supply)
func BurnFeeHandler(_ sdk.Context, _ sdk.Tx, _ sdk.Coins) {}