Copy certifiers from light-client

certifiers/inquirer.go

@@ -0,0 +1,142 @@
+package certifiers
+
+import (
+	"github.com/tendermint/tendermint/types"
+
+	certerr "github.com/tendermint/tendermint/certifiers/errors"
+)
+
+type Inquiring struct {
+	cert *Dynamic
+	// These are only properly validated data, from local system
+	trusted Provider
+	// This is a source of new info, like a node rpc, or other import method
+	Source Provider
+}
+
+func NewInquiring(chainID string, fc FullCommit, trusted Provider, source Provider) *Inquiring {
+	// store the data in trusted
+	trusted.StoreCommit(fc)
+
+	return &Inquiring{
+		cert:    NewDynamic(chainID, fc.Validators, fc.Height()),
+		trusted: trusted,
+		Source:  source,
+	}
+}
+
+func (c *Inquiring) ChainID() string {
+	return c.cert.ChainID()
+}
+
+func (c *Inquiring) Validators() *types.ValidatorSet {
+	return c.cert.cert.vSet
+}
+
+func (c *Inquiring) LastHeight() int {
+	return c.cert.lastHeight
+}
+
+// Certify makes sure this is checkpoint is valid.
+//
+// If the validators have changed since the last know time, it looks
+// for a path to prove the new validators.
+//
+// On success, it will store the checkpoint in the store for later viewing
+func (c *Inquiring) Certify(commit *Commit) error {
+	err := c.useClosestTrust(commit.Height())
+	if err != nil {
+		return err
+	}
+
+	err = c.cert.Certify(commit)
+	if !certerr.IsValidatorsChangedErr(err) {
+		return err
+	}
+	err = c.updateToHash(commit.Header.ValidatorsHash)
+	if err != nil {
+		return err
+	}
+
+	err = c.cert.Certify(commit)
+	if err != nil {
+		return err
+	}
+
+	// store the new checkpoint
+	c.trusted.StoreCommit(
+		NewFullCommit(commit, c.Validators()))
+	return nil
+}
+
+func (c *Inquiring) Update(fc FullCommit) error {
+	err := c.useClosestTrust(fc.Height())
+	if err != nil {
+		return err
+	}
+
+	err = c.cert.Update(fc)
+	if err == nil {
+		c.trusted.StoreCommit(fc)
+	}
+	return err
+}
+
+func (c *Inquiring) useClosestTrust(h int) error {
+	closest, err := c.trusted.GetByHeight(h)
+	if err != nil {
+		return err
+	}
+
+	// if the best seed is not the one we currently use,
+	// let's just reset the dynamic validator
+	if closest.Height() != c.LastHeight() {
+		c.cert = NewDynamic(c.ChainID(), closest.Validators, closest.Height())
+	}
+	return nil
+}
+
+// updateToHash gets the validator hash we want to update to
+// if IsTooMuchChangeErr, we try to find a path by binary search over height
+func (c *Inquiring) updateToHash(vhash []byte) error {
+	// try to get the match, and update
+	fc, err := c.Source.GetByHash(vhash)
+	if err != nil {
+		return err
+	}
+	err = c.cert.Update(fc)
+	// handle IsTooMuchChangeErr by using divide and conquer
+	if certerr.IsTooMuchChangeErr(err) {
+		err = c.updateToHeight(fc.Height())
+	}
+	return err
+}
+
+// updateToHeight will use divide-and-conquer to find a path to h
+func (c *Inquiring) updateToHeight(h int) error {
+	// try to update to this height (with checks)
+	fc, err := c.Source.GetByHeight(h)
+	if err != nil {
+		return err
+	}
+	start, end := c.LastHeight(), fc.Height()
+	if end <= start {
+		return certerr.ErrNoPathFound()
+	}
+	err = c.Update(fc)
+
+	// we can handle IsTooMuchChangeErr specially
+	if !certerr.IsTooMuchChangeErr(err) {
+		return err
+	}
+
+	// try to update to mid
+	mid := (start + end) / 2
+	err = c.updateToHeight(mid)
+	if err != nil {
+		return err
+	}
+
+	// if we made it to mid, we recurse
+	return c.updateToHeight(h)
+}