package lite import ( "bytes" "github.com/pkg/errors" "github.com/tendermint/tendermint/types" liteErr "github.com/tendermint/tendermint/lite/errors" ) // Certifier checks the votes to make sure the block really is signed properly. // Certifier must know the current set of validitors by some other means. type Certifier interface { Certify(check Commit) error ChainID() string } // Commit is basically the rpc /commit response, but extended // // This is the basepoint for proving anything on the blockchain. It contains // a signed header. If the signatures are valid and > 2/3 of the known set, // we can store this checkpoint and use it to prove any number of aspects of // the system: such as txs, abci state, validator sets, etc... type Commit types.SignedHeader // FullCommit is a commit and the actual validator set, // the base info you need to update to a given point, // assuming knowledge of some previous validator set type FullCommit struct { Commit `json:"commit"` Validators *types.ValidatorSet `json:"validator_set"` } // NewFullCommit returns a new FullCommit. func NewFullCommit(commit Commit, vals *types.ValidatorSet) FullCommit { return FullCommit{ Commit: commit, Validators: vals, } } // Height returns the height of the header. func (c Commit) Height() int64 { if c.Header == nil { return 0 } return c.Header.Height } // ValidatorsHash returns the hash of the validator set. func (c Commit) ValidatorsHash() []byte { if c.Header == nil { return nil } return c.Header.ValidatorsHash } // ValidateBasic does basic consistency checks and makes sure the headers // and commits are all consistent and refer to our chain. // // Make sure to use a Verifier to validate the signatures actually provide // a significantly strong proof for this header's validity. func (c Commit) ValidateBasic(chainID string) error { // make sure the header is reasonable if c.Header == nil { return errors.New("Commit missing header") } if c.Header.ChainID != chainID { return errors.Errorf("Header belongs to another chain '%s' not '%s'", c.Header.ChainID, chainID) } if c.Commit == nil { return errors.New("Commit missing signatures") } // make sure the header and commit match (height and hash) if c.Commit.Height() != c.Header.Height { return liteErr.ErrHeightMismatch(c.Commit.Height(), c.Header.Height) } hhash := c.Header.Hash() chash := c.Commit.BlockID.Hash if !bytes.Equal(hhash, chash) { return errors.Errorf("Commits sign block %X header is block %X", chash, hhash) } // make sure the commit is reasonable err := c.Commit.ValidateBasic() if err != nil { return errors.WithStack(err) } // looks good, we just need to make sure the signatures are really from // empowered validators return nil }