Copy certifiers from light-client

certifiers/static.go

@@ -0,0 +1,66 @@
+package certifiers
+
+import (
+	"bytes"
+
+	"github.com/pkg/errors"
+
+	"github.com/tendermint/tendermint/types"
+
+	certerr "github.com/tendermint/tendermint/certifiers/errors"
+)
+
+var _ Certifier = &Static{}
+
+// Static assumes a static set of validators, set on
+// initilization and checks against them.
+// The signatures on every header is checked for > 2/3 votes
+// against the known validator set upon Certify
+//
+// Good for testing or really simple chains.  Building block
+// to support real-world functionality.
+type Static struct {
+	chainID string
+	vSet    *types.ValidatorSet
+	vhash   []byte
+}
+
+func NewStatic(chainID string, vals *types.ValidatorSet) *Static {
+	return &Static{
+		chainID: chainID,
+		vSet:    vals,
+	}
+}
+
+func (c *Static) ChainID() string {
+	return c.chainID
+}
+
+func (c *Static) Validators() *types.ValidatorSet {
+	return c.vSet
+}
+
+func (c *Static) Hash() []byte {
+	if len(c.vhash) == 0 {
+		c.vhash = c.vSet.Hash()
+	}
+	return c.vhash
+}
+
+func (c *Static) Certify(commit *Commit) error {
+	// do basic sanity checks
+	err := commit.ValidateBasic(c.chainID)
+	if err != nil {
+		return err
+	}
+
+	// make sure it has the same validator set we have (static means static)
+	if !bytes.Equal(c.Hash(), commit.Header.ValidatorsHash) {
+		return certerr.ErrValidatorsChanged()
+	}
+
+	// then make sure we have the proper signatures for this
+	err = c.vSet.VerifyCommit(c.chainID, commit.Commit.BlockID,
+		commit.Header.Height, commit.Commit)
+	return errors.WithStack(err)
+}