Official Go implementation of the Ethereum protocol
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go-ethereum/cmd/devp2p/dns_route53.go

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// Copyright 2019 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
package main
import (
"context"
"errors"
"fmt"
"strconv"
"strings"
"time"
"github.com/aws/aws-sdk-go-v2/aws"
"github.com/aws/aws-sdk-go-v2/config"
"github.com/aws/aws-sdk-go-v2/credentials"
"github.com/aws/aws-sdk-go-v2/service/route53"
"github.com/aws/aws-sdk-go-v2/service/route53/types"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/dnsdisc"
"github.com/urfave/cli/v2"
"golang.org/x/exp/slices"
)
const (
// Route53 limits change sets to 32k of 'RDATA size'. Change sets are also limited to
// 1000 items. UPSERTs count double.
// https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/DNSLimitations.html#limits-api-requests-changeresourcerecordsets
route53ChangeSizeLimit = 32000
route53ChangeCountLimit = 1000
maxRetryLimit = 60
)
var (
route53AccessKeyFlag = &cli.StringFlag{
Name: "access-key-id",
Usage: "AWS Access Key ID",
EnvVars: []string{"AWS_ACCESS_KEY_ID"},
}
route53AccessSecretFlag = &cli.StringFlag{
Name: "access-key-secret",
Usage: "AWS Access Key Secret",
EnvVars: []string{"AWS_SECRET_ACCESS_KEY"},
}
route53ZoneIDFlag = &cli.StringFlag{
Name: "zone-id",
Usage: "Route53 Zone ID",
}
route53RegionFlag = &cli.StringFlag{
Name: "aws-region",
Usage: "AWS Region",
Value: "eu-central-1",
}
)
type route53Client struct {
api *route53.Client
zoneID string
}
type recordSet struct {
values []string
ttl int64
}
// newRoute53Client sets up a Route53 API client from command line flags.
func newRoute53Client(ctx *cli.Context) *route53Client {
akey := ctx.String(route53AccessKeyFlag.Name)
asec := ctx.String(route53AccessSecretFlag.Name)
if akey == "" || asec == "" {
exit(errors.New("need Route53 Access Key ID and secret to proceed"))
}
creds := aws.NewCredentialsCache(credentials.NewStaticCredentialsProvider(akey, asec, ""))
cfg, err := config.LoadDefaultConfig(context.Background(), config.WithCredentialsProvider(creds))
if err != nil {
exit(fmt.Errorf("can't initialize AWS configuration: %v", err))
}
cfg.Region = ctx.String(route53RegionFlag.Name)
return &route53Client{
api: route53.NewFromConfig(cfg),
zoneID: ctx.String(route53ZoneIDFlag.Name),
}
}
// deploy uploads the given tree to Route53.
func (c *route53Client) deploy(name string, t *dnsdisc.Tree) error {
if err := c.checkZone(name); err != nil {
return err
}
// Compute DNS changes.
existing, err := c.collectRecords(name)
if err != nil {
return err
}
log.Info(fmt.Sprintf("Found %d TXT records", len(existing)))
records := t.ToTXT(name)
changes := c.computeChanges(name, records, existing)
// Submit to API.
comment := fmt.Sprintf("enrtree update of %s at seq %d", name, t.Seq())
return c.submitChanges(changes, comment)
}
// deleteDomain removes all TXT records of the given domain.
func (c *route53Client) deleteDomain(name string) error {
if err := c.checkZone(name); err != nil {
return err
}
// Compute DNS changes.
existing, err := c.collectRecords(name)
if err != nil {
return err
}
log.Info(fmt.Sprintf("Found %d TXT records", len(existing)))
changes := makeDeletionChanges(existing, nil)
// Submit to API.
comment := "enrtree delete of " + name
return c.submitChanges(changes, comment)
}
// submitChanges submits the given DNS changes to Route53.
func (c *route53Client) submitChanges(changes []types.Change, comment string) error {
if len(changes) == 0 {
log.Info("No DNS changes needed")
return nil
}
var err error
batches := splitChanges(changes, route53ChangeSizeLimit, route53ChangeCountLimit)
changesToCheck := make([]*route53.ChangeResourceRecordSetsOutput, len(batches))
for i, changes := range batches {
log.Info(fmt.Sprintf("Submitting %d changes to Route53", len(changes)))
batch := &types.ChangeBatch{
Changes: changes,
Comment: aws.String(fmt.Sprintf("%s (%d/%d)", comment, i+1, len(batches))),
}
req := &route53.ChangeResourceRecordSetsInput{HostedZoneId: &c.zoneID, ChangeBatch: batch}
changesToCheck[i], err = c.api.ChangeResourceRecordSets(context.TODO(), req)
if err != nil {
return err
}
}
// Wait for all change batches to propagate.
for _, change := range changesToCheck {
log.Info(fmt.Sprintf("Waiting for change request %s", *change.ChangeInfo.Id))
wreq := &route53.GetChangeInput{Id: change.ChangeInfo.Id}
var count int
for {
wresp, err := c.api.GetChange(context.TODO(), wreq)
if err != nil {
return err
}
count++
if wresp.ChangeInfo.Status == types.ChangeStatusInsync || count >= maxRetryLimit {
break
}
time.Sleep(30 * time.Second)
}
}
return nil
}
// checkZone verifies zone information for the given domain.
func (c *route53Client) checkZone(name string) (err error) {
if c.zoneID == "" {
c.zoneID, err = c.findZoneID(name)
}
return err
}
// findZoneID searches for the Zone ID containing the given domain.
func (c *route53Client) findZoneID(name string) (string, error) {
log.Info(fmt.Sprintf("Finding Route53 Zone ID for %s", name))
var req route53.ListHostedZonesByNameInput
for {
resp, err := c.api.ListHostedZonesByName(context.TODO(), &req)
if err != nil {
return "", err
}
for _, zone := range resp.HostedZones {
if isSubdomain(name, *zone.Name) {
return *zone.Id, nil
}
}
if !resp.IsTruncated {
break
}
req.DNSName = resp.NextDNSName
req.HostedZoneId = resp.NextHostedZoneId
}
return "", errors.New("can't find zone ID for " + name)
}
// computeChanges creates DNS changes for the given set of DNS discovery records.
// The 'existing' arg is the set of records that already exist on Route53.
func (c *route53Client) computeChanges(name string, records map[string]string, existing map[string]recordSet) []types.Change {
// Convert all names to lowercase.
lrecords := make(map[string]string, len(records))
for name, r := range records {
lrecords[strings.ToLower(name)] = r
}
records = lrecords
var (
changes []types.Change
inserts int
upserts int
skips int
)
for path, newValue := range records {
prevRecords, exists := existing[path]
prevValue := strings.Join(prevRecords.values, "")
// prevValue contains quoted strings, encode newValue to compare.
newValue = splitTXT(newValue)
// Assign TTL.
ttl := int64(rootTTL)
if path != name {
ttl = int64(treeNodeTTL)
}
if !exists {
// Entry is unknown, push a new one
log.Debug(fmt.Sprintf("Creating %s = %s", path, newValue))
changes = append(changes, newTXTChange("CREATE", path, ttl, newValue))
inserts++
} else if prevValue != newValue || prevRecords.ttl != ttl {
// Entry already exists, only change its content.
log.Info(fmt.Sprintf("Updating %s from %s to %s", path, prevValue, newValue))
changes = append(changes, newTXTChange("UPSERT", path, ttl, newValue))
upserts++
} else {
log.Debug(fmt.Sprintf("Skipping %s = %s", path, newValue))
skips++
}
}
// Iterate over the old records and delete anything stale.
deletions := makeDeletionChanges(existing, records)
changes = append(changes, deletions...)
log.Info("Computed DNS changes",
"changes", len(changes),
"inserts", inserts,
"skips", skips,
"deleted", len(deletions),
"upserts", upserts)
// Ensure changes are in the correct order.
sortChanges(changes)
return changes
}
// makeDeletionChanges creates record changes which delete all records not contained in 'keep'.
func makeDeletionChanges(records map[string]recordSet, keep map[string]string) []types.Change {
var changes []types.Change
for path, set := range records {
if _, ok := keep[path]; ok {
continue
}
log.Debug(fmt.Sprintf("Deleting %s = %s", path, strings.Join(set.values, "")))
changes = append(changes, newTXTChange("DELETE", path, set.ttl, set.values...))
}
return changes
}
// sortChanges ensures DNS changes are in leaf-added -> root-changed -> leaf-deleted order.
func sortChanges(changes []types.Change) {
score := map[string]int{"CREATE": 1, "UPSERT": 2, "DELETE": 3}
slices.SortFunc(changes, func(a, b types.Change) bool {
if a.Action == b.Action {
return *a.ResourceRecordSet.Name < *b.ResourceRecordSet.Name
}
return score[string(a.Action)] < score[string(b.Action)]
})
}
// splitChanges splits up DNS changes such that each change batch
// is smaller than the given RDATA limit.
func splitChanges(changes []types.Change, sizeLimit, countLimit int) [][]types.Change {
var (
batches [][]types.Change
batchSize int
batchCount int
)
for _, ch := range changes {
// Start new batch if this change pushes the current one over the limit.
count := changeCount(ch)
size := changeSize(ch) * count
overSize := batchSize+size > sizeLimit
overCount := batchCount+count > countLimit
if len(batches) == 0 || overSize || overCount {
batches = append(batches, nil)
batchSize = 0
batchCount = 0
}
batches[len(batches)-1] = append(batches[len(batches)-1], ch)
batchSize += size
batchCount += count
}
return batches
}
// changeSize returns the RDATA size of a DNS change.
func changeSize(ch types.Change) int {
size := 0
for _, rr := range ch.ResourceRecordSet.ResourceRecords {
if rr.Value != nil {
size += len(*rr.Value)
}
}
return size
}
func changeCount(ch types.Change) int {
if ch.Action == types.ChangeActionUpsert {
return 2
}
return 1
}
// collectRecords collects all TXT records below the given name.
func (c *route53Client) collectRecords(name string) (map[string]recordSet, error) {
var req route53.ListResourceRecordSetsInput
req.HostedZoneId = &c.zoneID
existing := make(map[string]recordSet)
log.Info("Loading existing TXT records", "name", name, "zone", c.zoneID)
for page := 0; ; page++ {
log.Debug("Loading existing TXT records", "name", name, "zone", c.zoneID, "page", page)
resp, err := c.api.ListResourceRecordSets(context.TODO(), &req)
if err != nil {
return existing, err
}
for _, set := range resp.ResourceRecordSets {
if !isSubdomain(*set.Name, name) || set.Type != types.RRTypeTxt {
continue
}
s := recordSet{ttl: *set.TTL}
for _, rec := range set.ResourceRecords {
s.values = append(s.values, *rec.Value)
}
name := strings.TrimSuffix(*set.Name, ".")
existing[name] = s
}
if !resp.IsTruncated {
break
}
// Set the cursor to the next batch. From the AWS docs:
//
// To display the next page of results, get the values of NextRecordName,
// NextRecordType, and NextRecordIdentifier (if any) from the response. Then submit
// another ListResourceRecordSets request, and specify those values for
// StartRecordName, StartRecordType, and StartRecordIdentifier.
req.StartRecordIdentifier = resp.NextRecordIdentifier
req.StartRecordName = resp.NextRecordName
req.StartRecordType = resp.NextRecordType
}
log.Info("Loaded existing TXT records", "name", name, "zone", c.zoneID, "records", len(existing))
return existing, nil
}
// newTXTChange creates a change to a TXT record.
func newTXTChange(action, name string, ttl int64, values ...string) types.Change {
r := types.ResourceRecordSet{
Type: types.RRTypeTxt,
Name: &name,
TTL: &ttl,
}
var rrs []types.ResourceRecord
for _, val := range values {
var rr types.ResourceRecord
rr.Value = aws.String(val)
rrs = append(rrs, rr)
}
r.ResourceRecords = rrs
return types.Change{
Action: types.ChangeAction(action),
ResourceRecordSet: &r,
}
}
// isSubdomain returns true if name is a subdomain of domain.
func isSubdomain(name, domain string) bool {
domain = strings.TrimSuffix(domain, ".")
name = strings.TrimSuffix(name, ".")
return strings.HasSuffix("."+name, "."+domain)
}
// splitTXT splits value into a list of quoted 255-character strings.
func splitTXT(value string) string {
var result strings.Builder
for len(value) > 0 {
rlen := len(value)
if rlen > 253 {
rlen = 253
}
result.WriteString(strconv.Quote(value[:rlen]))
value = value[rlen:]
}
return result.String()
}