/
near.go
314 lines (264 loc) · 8.12 KB
/
near.go
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package near
import (
"bytes"
"context"
"encoding/json"
"fmt"
"strings"
"time"
b64 "encoding/base64"
nearclient "github.com/CrossChainLabs/near-api-go"
"github.com/coredns/coredns/plugin"
"github.com/coredns/coredns/request"
"github.com/labstack/gommon/log"
"github.com/miekg/dns"
)
var emptyContentHash = []byte{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
type NEAR struct {
Next plugin.Handler
Client *nearclient.Client
NEARDNS string
NEARLinkNameServers []string
IPFSGatewayAs []string
IPFSGatewayAAAAs []string
}
func (n NEAR) IsAuthoritative(domain string) bool {
return true
}
func (n NEAR) HasRecords(domain string, name string) (bool, error) {
return true, nil
}
func (n NEAR) Query(domain string, name string, qtype uint16, do bool) ([]dns.RR, error) {
results := make([]dns.RR, 0)
var contentHash []byte
hasContentHash := false
var err error
if qtype == dns.TypeSOA ||
qtype == dns.TypeNS ||
qtype == dns.TypeTXT ||
qtype == dns.TypeA ||
qtype == dns.TypeAAAA {
contentHash, err = n.obtainContentHash(name, domain)
hasContentHash = err == nil && bytes.Compare(contentHash, emptyContentHash) > 0
}
if hasContentHash {
switch qtype {
case dns.TypeSOA:
results, err = n.handleSOA(name, domain, contentHash)
case dns.TypeNS:
results, err = n.handleNS(name, domain, contentHash)
case dns.TypeTXT:
results, err = n.handleTXT(name, domain, contentHash)
case dns.TypeA:
results, err = n.handleA(name, domain, contentHash)
case dns.TypeAAAA:
results, err = n.handleAAAA(name, domain, contentHash)
}
}
return results, err
}
func (n NEAR) handleSOA(name string, domain string, contentHash []byte) ([]dns.RR, error) {
results := make([]dns.RR, 0)
if len(n.NEARLinkNameServers) > 0 {
// Create a synthetic SOA record
now := time.Now()
ser := ((now.Hour()*3600 + now.Minute()) * 100) / 86400
dateStr := fmt.Sprintf("%04d%02d%02d%02d", now.Year(), now.Month(), now.Day(), ser)
result, err := dns.NewRR(fmt.Sprintf("%s 10800 IN SOA %s hostmaster.%s %s 3600 600 1209600 300", n.NEARLinkNameServers[0], name, name, dateStr))
if err != nil {
return results, err
}
results = append(results, result)
}
return results, nil
}
func (n NEAR) handleNS(name string, domain string, contentHash []byte) ([]dns.RR, error) {
results := make([]dns.RR, 0)
for _, nameserver := range n.NEARLinkNameServers {
result, err := dns.NewRR(fmt.Sprintf("%s 3600 IN NS %s", domain, nameserver))
if err != nil {
return results, err
}
results = append(results, result)
}
return results, nil
}
func (n NEAR) handleTXT(name string, domain string, contentHash []byte) ([]dns.RR, error) {
results := make([]dns.RR, 0)
txtRRSet, err := n.obtainTXTRRSet(name, domain)
if err == nil && len(txtRRSet) != 0 {
// We have a TXT rrset; use it
offset := 0
for offset < len(txtRRSet) {
var result dns.RR
result, offset, err = dns.UnpackRR(txtRRSet, offset)
if err == nil {
results = append(results, result)
}
}
}
result, err := dns.NewRR(fmt.Sprintf("%s 3600 IN TXT \"contenthash=0x%s\"", name, contentHash))
if err != nil {
return results, err
}
results = append(results, result)
return results, nil
}
func (n NEAR) handleA(name string, domain string, contentHash []byte) ([]dns.RR, error) {
results := make([]dns.RR, 0)
aRRSet, err := n.obtainARRSet(name, domain)
if err == nil && len(aRRSet) != 0 {
// We have an A rrset; use it
offset := 0
for offset < len(aRRSet) {
var result dns.RR
result, offset, err = dns.UnpackRR(aRRSet, offset)
if err == nil {
results = append(results, result)
}
}
} else {
// We have a content hash but no A record; use the default
for i := range n.IPFSGatewayAs {
result, err := dns.NewRR(fmt.Sprintf("%s 3600 IN A %s", name, n.IPFSGatewayAs[i]))
if err != nil {
return results, err
}
results = append(results, result)
}
}
return results, nil
}
func (n NEAR) handleAAAA(name string, domain string, contentHash []byte) ([]dns.RR, error) {
results := make([]dns.RR, 0)
aaaaRRSet, err := n.obtainAAAARRSet(name, domain)
if err == nil && len(aaaaRRSet) != 0 {
// We have an AAAA rrset; use it
offset := 0
for offset < len(aaaaRRSet) {
var result dns.RR
result, offset, err = dns.UnpackRR(aaaaRRSet, offset)
if err == nil {
results = append(results, result)
}
}
} else {
// We have a content hash but no AAAA record; use the default
for i := range n.IPFSGatewayAAAAs {
result, err := dns.NewRR(fmt.Sprintf("%s 3600 IN AAAA %s", name, n.IPFSGatewayAAAAs[i]))
if err != nil {
log.Warnf("error creating %s AAAA RR: %v", name, err)
}
results = append(results, result)
}
}
return results, nil
}
// ServeDNS implements the plugin.Handler interface.
func (n NEAR) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
a := new(dns.Msg)
a.SetReply(r)
a.Compress = true
a.Authoritative = true
var result Result
a.Answer, a.Ns, a.Extra, result = Lookup(n, state)
switch result {
case Success:
state.SizeAndDo(a)
w.WriteMsg(a)
return dns.RcodeSuccess, nil
case NoData:
if n.Next == nil {
state.SizeAndDo(a)
w.WriteMsg(a)
return dns.RcodeSuccess, nil
}
return plugin.NextOrFailure(n.Name(), n.Next, ctx, w, r)
case NameError:
a.Rcode = dns.RcodeNameError
case ServerFailure:
return dns.RcodeServerFailure, nil
}
// Unknown result...
return dns.RcodeServerFailure, nil
}
func (n NEAR) obtainARRSet(name string, domain string) ([]byte, error) {
nearDomain := strings.TrimSuffix(domain, ".near.")
params := "{\"account_id\": \"" + nearDomain + "\"}"
paramsEnc := b64.StdEncoding.EncodeToString([]byte(params))
resp, err := n.Client.FunctionCall(n.NEARDNS, "get_a", paramsEnc)
if err != nil {
log.Error(err)
return nil, err
}
var byte_result []byte
if err := json.Unmarshal(resp.Result, &byte_result); err != nil {
log.Error(err)
return nil, err
}
dec := string(byte_result)
dec = strings.TrimPrefix(dec, "\"")
dec = strings.TrimSuffix(dec, "\"")
return []byte(dec), nil
}
func (n NEAR) obtainAAAARRSet(name string, domain string) ([]byte, error) {
nearDomain := strings.TrimSuffix(domain, ".near.")
params := "{\"account_id\": \"" + nearDomain + "\"}"
paramsEnc := b64.StdEncoding.EncodeToString([]byte(params))
resp, err := n.Client.FunctionCall(n.NEARDNS, "get_aaaa", paramsEnc)
if err != nil {
log.Error(err)
return nil, err
}
var byte_result []byte
if err := json.Unmarshal(resp.Result, &byte_result); err != nil {
log.Error(err)
return nil, err
}
dec := string(byte_result)
dec = strings.TrimPrefix(dec, "\"")
dec = strings.TrimSuffix(dec, "\"")
return []byte(dec), nil
}
func (n NEAR) obtainContentHash(name string, domain string) ([]byte, error) {
nearDomain := strings.TrimSuffix(domain, ".near.")
params := "{\"account_id\": \"" + nearDomain + "\"}"
paramsEnc := b64.StdEncoding.EncodeToString([]byte(params))
resp, err := n.Client.FunctionCall(n.NEARDNS, "get_content_hash", paramsEnc)
if err != nil {
log.Error(err)
return nil, err
}
var byte_result []byte
if err := json.Unmarshal(resp.Result, &byte_result); err != nil {
log.Error(err)
return nil, err
}
dec := string(byte_result)
dec = strings.TrimPrefix(dec, "\"")
dec = strings.TrimSuffix(dec, "\"")
return []byte(dec), nil
}
func (n NEAR) obtainTXTRRSet(name string, domain string) ([]byte, error) {
nearDomain := strings.TrimSuffix(domain, ".near.")
params := "{\"account_id\": \"" + nearDomain + "\"}"
paramsEnc := b64.StdEncoding.EncodeToString([]byte(params))
resp, err := n.Client.FunctionCall(n.NEARDNS, "get_txt", paramsEnc)
if err != nil {
log.Error(err)
return nil, err
}
var byte_result []byte
if err := json.Unmarshal(resp.Result, &byte_result); err != nil {
log.Error(err)
return nil, err
}
dec := string(byte_result)
dec = strings.TrimPrefix(dec, "\"")
dec = strings.TrimSuffix(dec, "\"")
return []byte(dec), nil
}
// Name implements the Handler interface.
func (n NEAR) Name() string { return "near" }
func (n NEAR) Ready() bool { return true }