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171 lines
4.5 KiB
171 lines
4.5 KiB
package http
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import (
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"context"
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"fmt"
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"math/rand"
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"regexp"
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"strings"
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"time"
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"github.com/tendermint/tendermint/light/provider"
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rpcclient "github.com/tendermint/tendermint/rpc/client"
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rpchttp "github.com/tendermint/tendermint/rpc/client/http"
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"github.com/tendermint/tendermint/types"
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)
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// This is very brittle, see: https://github.com/tendermint/tendermint/issues/4740
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var (
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regexpMissingHeight = regexp.MustCompile(`height \d+ (must be less than or equal to|is not available)`)
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maxRetryAttempts = 10
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)
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// http provider uses an RPC client to obtain the necessary information.
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type http struct {
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chainID string
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client rpcclient.RemoteClient
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}
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// New creates a HTTP provider, which is using the rpchttp.HTTP client under
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// the hood. If no scheme is provided in the remote URL, http will be used by
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// default.
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func New(chainID, remote string) (provider.Provider, error) {
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// Ensure URL scheme is set (default HTTP) when not provided.
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if !strings.Contains(remote, "://") {
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remote = "http://" + remote
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}
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httpClient, err := rpchttp.New(remote, "/websocket")
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if err != nil {
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return nil, err
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}
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return NewWithClient(chainID, httpClient), nil
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}
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// NewWithClient allows you to provide a custom client.
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func NewWithClient(chainID string, client rpcclient.RemoteClient) provider.Provider {
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return &http{
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client: client,
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chainID: chainID,
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}
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}
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func (p *http) String() string {
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return fmt.Sprintf("http{%s}", p.client.Remote())
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}
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// LightBlock fetches a LightBlock at the given height and checks the
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// chainID matches.
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func (p *http) LightBlock(ctx context.Context, height int64) (*types.LightBlock, error) {
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h, err := validateHeight(height)
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if err != nil {
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return nil, provider.ErrBadLightBlock{Reason: err}
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}
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sh, err := p.signedHeader(ctx, h)
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if err != nil {
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return nil, err
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}
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vs, err := p.validatorSet(ctx, h)
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if err != nil {
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return nil, err
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}
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lb := &types.LightBlock{
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SignedHeader: sh,
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ValidatorSet: vs,
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}
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err = lb.ValidateBasic(p.chainID)
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if err != nil {
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return nil, provider.ErrBadLightBlock{Reason: err}
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}
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return lb, nil
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}
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// ReportEvidence calls `/broadcast_evidence` endpoint.
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func (p *http) ReportEvidence(ctx context.Context, ev types.Evidence) error {
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_, err := p.client.BroadcastEvidence(ctx, ev)
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return err
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}
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func (p *http) validatorSet(ctx context.Context, height *int64) (*types.ValidatorSet, error) {
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var (
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maxPerPage = 100
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vals = []*types.Validator{}
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page = 1
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)
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for len(vals)%maxPerPage == 0 {
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for attempt := 1; attempt <= maxRetryAttempts; attempt++ {
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res, err := p.client.Validators(ctx, height, &page, &maxPerPage)
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if err != nil {
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// TODO: standardize errors on the RPC side
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if regexpMissingHeight.MatchString(err.Error()) {
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return nil, provider.ErrLightBlockNotFound
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}
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// if we have exceeded retry attempts then return no response error
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if attempt == maxRetryAttempts {
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return nil, provider.ErrNoResponse
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}
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// else we wait and try again with exponential backoff
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time.Sleep(backoffTimeout(uint16(attempt)))
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continue
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}
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if len(res.Validators) == 0 { // no more validators left
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valSet, err := types.ValidatorSetFromExistingValidators(vals)
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if err != nil {
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return nil, provider.ErrBadLightBlock{Reason: err}
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}
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return valSet, nil
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}
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vals = append(vals, res.Validators...)
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page++
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break
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}
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}
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valSet, err := types.ValidatorSetFromExistingValidators(vals)
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if err != nil {
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return nil, provider.ErrBadLightBlock{Reason: err}
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}
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return valSet, nil
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}
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func (p *http) signedHeader(ctx context.Context, height *int64) (*types.SignedHeader, error) {
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for attempt := 1; attempt <= maxRetryAttempts; attempt++ {
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commit, err := p.client.Commit(ctx, height)
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if err != nil {
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// TODO: standardize errors on the RPC side
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if regexpMissingHeight.MatchString(err.Error()) {
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return nil, provider.ErrLightBlockNotFound
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}
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// we wait and try again with exponential backoff
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time.Sleep(backoffTimeout(uint16(attempt)))
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continue
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}
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return &commit.SignedHeader, nil
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}
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return nil, provider.ErrNoResponse
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}
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func validateHeight(height int64) (*int64, error) {
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if height < 0 {
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return nil, fmt.Errorf("expected height >= 0, got height %d", height)
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}
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h := &height
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if height == 0 {
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h = nil
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}
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return h, nil
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}
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// exponential backoff (with jitter)
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// 0.5s -> 2s -> 4.5s -> 8s -> 12.5 with 1s variation
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func backoffTimeout(attempt uint16) time.Duration {
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// nolint:gosec // G404: Use of weak random number generator
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return time.Duration(500*attempt*attempt)*time.Millisecond + time.Duration(rand.Intn(1000))*time.Millisecond
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}
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