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p2p/dnsdisc: add implementation of EIP-1459 (#20094)
This adds an implementation of node discovery via DNS TXT records to the go-ethereum library. The implementation doesn't match EIP-1459 exactly, the main difference being that this implementation uses separate merkle trees for tree links and ENRs. The EIP will be updated to match p2p/dnsdisc. To maintain DNS trees, cmd/devp2p provides a frontend for the p2p/dnsdisc library. The new 'dns' subcommands can be used to create, sign and deploy DNS discovery trees.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,163 @@ | ||
| // 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 ( | ||
| "fmt" | ||
| "strings" | ||
|
|
||
| "github.com/cloudflare/cloudflare-go" | ||
| "github.com/ethereum/go-ethereum/log" | ||
| "github.com/ethereum/go-ethereum/p2p/dnsdisc" | ||
| "gopkg.in/urfave/cli.v1" | ||
| ) | ||
|
|
||
| var ( | ||
| cloudflareTokenFlag = cli.StringFlag{ | ||
| Name: "token", | ||
| Usage: "CloudFlare API token", | ||
| EnvVar: "CLOUDFLARE_API_TOKEN", | ||
| } | ||
| cloudflareZoneIDFlag = cli.StringFlag{ | ||
| Name: "zoneid", | ||
| Usage: "CloudFlare Zone ID (optional)", | ||
| } | ||
| ) | ||
|
|
||
| type cloudflareClient struct { | ||
| *cloudflare.API | ||
| zoneID string | ||
| } | ||
|
|
||
| // newCloudflareClient sets up a CloudFlare API client from command line flags. | ||
| func newCloudflareClient(ctx *cli.Context) *cloudflareClient { | ||
| token := ctx.String(cloudflareTokenFlag.Name) | ||
| if token == "" { | ||
| exit(fmt.Errorf("need cloudflare API token to proceed")) | ||
| } | ||
| api, err := cloudflare.NewWithAPIToken(token) | ||
| if err != nil { | ||
| exit(fmt.Errorf("can't create Cloudflare client: %v", err)) | ||
| } | ||
| return &cloudflareClient{ | ||
| API: api, | ||
| zoneID: ctx.String(cloudflareZoneIDFlag.Name), | ||
| } | ||
| } | ||
|
|
||
| // deploy uploads the given tree to CloudFlare DNS. | ||
| func (c *cloudflareClient) deploy(name string, t *dnsdisc.Tree) error { | ||
| if err := c.checkZone(name); err != nil { | ||
| return err | ||
| } | ||
| records := t.ToTXT(name) | ||
| return c.uploadRecords(name, records) | ||
| } | ||
|
|
||
| // checkZone verifies permissions on the CloudFlare DNS Zone for name. | ||
| func (c *cloudflareClient) checkZone(name string) error { | ||
| if c.zoneID == "" { | ||
| log.Info(fmt.Sprintf("Finding CloudFlare zone ID for %s", name)) | ||
| id, err := c.ZoneIDByName(name) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| c.zoneID = id | ||
| } | ||
| log.Info(fmt.Sprintf("Checking Permissions on zone %s", c.zoneID)) | ||
| zone, err := c.ZoneDetails(c.zoneID) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| if !strings.HasSuffix(name, "."+zone.Name) { | ||
| return fmt.Errorf("CloudFlare zone name %q does not match name %q to be deployed", zone.Name, name) | ||
| } | ||
| needPerms := map[string]bool{"#zone:edit": false, "#zone:read": false} | ||
| for _, perm := range zone.Permissions { | ||
| if _, ok := needPerms[perm]; ok { | ||
| needPerms[perm] = true | ||
| } | ||
| } | ||
| for _, ok := range needPerms { | ||
| if !ok { | ||
| return fmt.Errorf("wrong permissions on zone %s: %v", c.zoneID, needPerms) | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // uploadRecords updates the TXT records at a particular subdomain. All non-root records | ||
| // will have a TTL of "infinity" and all existing records not in the new map will be | ||
| // nuked! | ||
| func (c *cloudflareClient) uploadRecords(name string, records map[string]string) error { | ||
| // Convert all names to lowercase. | ||
| lrecords := make(map[string]string, len(records)) | ||
| for name, r := range records { | ||
| lrecords[strings.ToLower(name)] = r | ||
| } | ||
| records = lrecords | ||
|
|
||
| log.Info(fmt.Sprintf("Retrieving existing TXT records on %s", name)) | ||
| entries, err := c.DNSRecords(c.zoneID, cloudflare.DNSRecord{Type: "TXT"}) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| existing := make(map[string]cloudflare.DNSRecord) | ||
| for _, entry := range entries { | ||
| if !strings.HasSuffix(entry.Name, name) { | ||
| continue | ||
| } | ||
| existing[strings.ToLower(entry.Name)] = entry | ||
| } | ||
|
|
||
| // Iterate over the new records and inject anything missing. | ||
| for path, val := range records { | ||
| old, exists := existing[path] | ||
| if !exists { | ||
| // Entry is unknown, push a new one to Cloudflare. | ||
| log.Info(fmt.Sprintf("Creating %s = %q", path, val)) | ||
| ttl := 1 | ||
| if path != name { | ||
| ttl = 2147483647 // Max TTL permitted by Cloudflare | ||
| } | ||
| _, err = c.CreateDNSRecord(c.zoneID, cloudflare.DNSRecord{Type: "TXT", Name: path, Content: val, TTL: ttl}) | ||
| } else if old.Content != val { | ||
| // Entry already exists, only change its content. | ||
| log.Info(fmt.Sprintf("Updating %s from %q to %q", path, old.Content, val)) | ||
| old.Content = val | ||
| err = c.UpdateDNSRecord(c.zoneID, old.ID, old) | ||
| } else { | ||
| log.Info(fmt.Sprintf("Skipping %s = %q", path, val)) | ||
| } | ||
| if err != nil { | ||
| return fmt.Errorf("failed to publish %s: %v", path, err) | ||
| } | ||
| } | ||
|
|
||
| // Iterate over the old records and delete anything stale. | ||
| for path, entry := range existing { | ||
| if _, ok := records[path]; ok { | ||
| continue | ||
| } | ||
| // Stale entry, nuke it. | ||
| log.Info(fmt.Sprintf("Deleting %s = %q", path, entry.Content)) | ||
| if err := c.DeleteDNSRecord(c.zoneID, entry.ID); err != nil { | ||
| return fmt.Errorf("failed to delete %s: %v", path, err) | ||
| } | ||
| } | ||
| return nil | ||
| } |
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