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159 lines
4.1 KiB
159 lines
4.1 KiB
package lite
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import (
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"github.com/tendermint/tendermint/types"
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liteErr "github.com/tendermint/tendermint/lite/errors"
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)
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// Inquiring wraps a dynamic certifier and implements an auto-update strategy. If a call to Certify
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// fails due to a change it validator set, Inquiring will try and find a previous FullCommit which
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// it can use to safely update the validator set. It uses a source provider to obtain the needed
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// FullCommits. It stores properly validated data on the local system.
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type Inquiring struct {
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cert *Dynamic
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// These are only properly validated data, from local system
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trusted Provider
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// This is a source of new info, like a node rpc, or other import method
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Source Provider
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}
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// NewInquiring returns a new Inquiring object. It uses the trusted provider to store validated
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// data and the source provider to obtain missing FullCommits.
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//
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// Example: The trusted provider should a CacheProvider, MemProvider or files.Provider. The source
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// provider should be a client.HTTPProvider.
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func NewInquiring(chainID string, fc FullCommit, trusted Provider,
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source Provider) (*Inquiring, error) {
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// store the data in trusted
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err := trusted.StoreCommit(fc)
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if err != nil {
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return nil, err
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}
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return &Inquiring{
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cert: NewDynamic(chainID, fc.Validators, fc.Height()),
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trusted: trusted,
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Source: source,
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}, nil
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}
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// ChainID returns the chain id.
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func (c *Inquiring) ChainID() string {
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return c.cert.ChainID()
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}
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// Validators returns the validator set.
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func (c *Inquiring) Validators() *types.ValidatorSet {
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return c.cert.cert.vSet
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}
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// LastHeight returns the last height.
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func (c *Inquiring) LastHeight() int64 {
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return c.cert.lastHeight
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}
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// Certify makes sure this is checkpoint is valid.
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//
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// If the validators have changed since the last know time, it looks
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// for a path to prove the new validators.
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//
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// On success, it will store the checkpoint in the store for later viewing
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func (c *Inquiring) Certify(commit Commit) error {
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err := c.useClosestTrust(commit.Height())
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if err != nil {
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return err
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}
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err = c.cert.Certify(commit)
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if !liteErr.IsValidatorsChangedErr(err) {
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return err
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}
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err = c.updateToHash(commit.Header.ValidatorsHash)
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if err != nil {
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return err
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}
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err = c.cert.Certify(commit)
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if err != nil {
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return err
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}
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// store the new checkpoint
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return c.trusted.StoreCommit(NewFullCommit(commit, c.Validators()))
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}
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// Update will verify if this is a valid change and update
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// the certifying validator set if safe to do so.
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func (c *Inquiring) Update(fc FullCommit) error {
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err := c.useClosestTrust(fc.Height())
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if err != nil {
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return err
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}
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err = c.cert.Update(fc)
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if err == nil {
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err = c.trusted.StoreCommit(fc)
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}
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return err
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}
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func (c *Inquiring) useClosestTrust(h int64) error {
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closest, err := c.trusted.GetByHeight(h)
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if err != nil {
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return err
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}
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// if the best seed is not the one we currently use,
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// let's just reset the dynamic validator
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if closest.Height() != c.LastHeight() {
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c.cert = NewDynamic(c.ChainID(), closest.Validators, closest.Height())
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}
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return nil
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}
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// updateToHash gets the validator hash we want to update to
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// if IsTooMuchChangeErr, we try to find a path by binary search over height
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func (c *Inquiring) updateToHash(vhash []byte) error {
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// try to get the match, and update
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fc, err := c.Source.GetByHash(vhash)
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if err != nil {
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return err
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}
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err = c.cert.Update(fc)
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// handle IsTooMuchChangeErr by using divide and conquer
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if liteErr.IsTooMuchChangeErr(err) {
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err = c.updateToHeight(fc.Height())
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}
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return err
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}
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// updateToHeight will use divide-and-conquer to find a path to h
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func (c *Inquiring) updateToHeight(h int64) error {
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// try to update to this height (with checks)
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fc, err := c.Source.GetByHeight(h)
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if err != nil {
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return err
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}
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start, end := c.LastHeight(), fc.Height()
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if end <= start {
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return liteErr.ErrNoPathFound()
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}
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err = c.Update(fc)
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// we can handle IsTooMuchChangeErr specially
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if !liteErr.IsTooMuchChangeErr(err) {
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return err
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}
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// try to update to mid
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mid := (start + end) / 2
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err = c.updateToHeight(mid)
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if err != nil {
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return err
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}
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// if we made it to mid, we recurse
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return c.updateToHeight(h)
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}
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