Rename checkpoint.go

certifiers/commit.go

@@ -0,0 +1,101 @@
+package certifiers
+
+import (
+	"bytes"
+
+	"github.com/pkg/errors"
+
+	rtypes "github.com/tendermint/tendermint/rpc/core/types"
+	"github.com/tendermint/tendermint/types"
+
+	certerr "github.com/tendermint/tendermint/certifiers/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 rtypes.ResultCommit
+
+// 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"`
+}
+
+func NewFullCommit(commit *Commit, vals *types.ValidatorSet) FullCommit {
+	return FullCommit{
+		Commit:     commit,
+		Validators: vals,
+	}
+}
+
+func CommitFromResult(commit *rtypes.ResultCommit) *Commit {
+	return (*Commit)(commit)
+}
+
+func (c *Commit) Height() int {
+	if c == nil || c.Header == nil {
+		return 0
+	}
+	return c.Header.Height
+}
+
+func (c *Commit) ValidatorsHash() []byte {
+	if c == nil || 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 certerr.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
+}