114 lines
4.1 KiB
Go
114 lines
4.1 KiB
Go
package tendermint
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import (
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"time"
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lite "github.com/tendermint/tendermint/lite2"
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sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
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clientexported "github.com/cosmos/cosmos-sdk/x/ibc/02-client/exported"
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clienttypes "github.com/cosmos/cosmos-sdk/x/ibc/02-client/types"
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"github.com/cosmos/cosmos-sdk/x/ibc/07-tendermint/types"
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commitmenttypes "github.com/cosmos/cosmos-sdk/x/ibc/23-commitment/types"
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)
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// CheckValidityAndUpdateState checks if the provided header is valid and updates
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// the consensus state if appropriate. It returns an error if:
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// - the client or header provided are not parseable to tendermint types
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// - the header is invalid
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// - header height is lower than the latest client height
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// - header valset commit verification fails
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//
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// Tendermint client validity checking uses the bisection algorithm described
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// in the [Tendermint spec](https://github.com/tendermint/spec/blob/master/spec/consensus/light-client.md).
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func CheckValidityAndUpdateState(
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clientState clientexported.ClientState, header clientexported.Header,
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currentTimestamp time.Time,
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) (clientexported.ClientState, clientexported.ConsensusState, error) {
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tmClientState, ok := clientState.(types.ClientState)
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if !ok {
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return nil, nil, sdkerrors.Wrap(
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clienttypes.ErrInvalidClientType, "light client is not from Tendermint",
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)
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}
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tmHeader, ok := header.(types.Header)
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if !ok {
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return nil, nil, sdkerrors.Wrap(
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clienttypes.ErrInvalidHeader, "header is not from Tendermint",
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)
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}
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if err := checkValidity(tmClientState, tmHeader, currentTimestamp); err != nil {
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return nil, nil, err
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}
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tmClientState, consensusState := update(tmClientState, tmHeader)
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return tmClientState, consensusState, nil
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}
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// checkValidity checks if the Tendermint header is valid.
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//
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// CONTRACT: assumes header.Height > consensusState.Height
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func checkValidity(
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clientState types.ClientState, header types.Header, currentTimestamp time.Time,
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) error {
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// assert trusting period has not yet passed
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if currentTimestamp.Sub(clientState.GetLatestTimestamp()) >= clientState.TrustingPeriod {
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return sdkerrors.Wrapf(
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types.ErrTrustingPeriodExpired,
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"current timestamp minus the latest trusted client state timestamp is greater than or equal to the trusting period (%s >= %s)",
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currentTimestamp.Sub(clientState.GetLatestTimestamp()), clientState.TrustingPeriod,
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)
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}
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// assert header timestamp is not past the trusting period
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if header.Time.Sub(clientState.GetLatestTimestamp()) >= clientState.TrustingPeriod {
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return sdkerrors.Wrap(
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clienttypes.ErrInvalidHeader,
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"header blocktime is outside trusting period from last client timestamp",
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)
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}
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// assert header timestamp is past latest clientstate timestamp
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if header.Time.Unix() <= clientState.GetLatestTimestamp().Unix() {
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return sdkerrors.Wrapf(
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clienttypes.ErrInvalidHeader,
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"header blocktime ≤ latest client state block time (%s ≤ %s)",
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header.Time.UTC(), clientState.GetLatestTimestamp().UTC(),
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)
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}
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// assert header height is newer than any we know
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if header.GetHeight() <= clientState.GetLatestHeight() {
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return sdkerrors.Wrapf(
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clienttypes.ErrInvalidHeader,
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"header height ≤ latest client state height (%d ≤ %d)", header.GetHeight(), clientState.GetLatestHeight(),
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)
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}
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// Verify next header with the last header's validatorset as trusted validatorset
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err := lite.Verify(
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clientState.GetChainID(), &clientState.LastHeader.SignedHeader,
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clientState.LastHeader.ValidatorSet, &header.SignedHeader, header.ValidatorSet,
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clientState.TrustingPeriod, currentTimestamp, clientState.MaxClockDrift, clientState.TrustLevel,
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)
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if err != nil {
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return sdkerrors.Wrap(clienttypes.ErrInvalidHeader, err.Error())
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}
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return nil
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}
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// update the consensus state from a new header
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func update(clientState types.ClientState, header types.Header) (types.ClientState, types.ConsensusState) {
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clientState.LastHeader = header
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consensusState := types.ConsensusState{
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Height: uint64(header.Height),
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Timestamp: header.Time,
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Root: commitmenttypes.NewMerkleRoot(header.AppHash),
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ValidatorSet: header.ValidatorSet,
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}
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return clientState, consensusState
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}
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