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dns.go
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dns.go
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package infra
import (
"context"
"errors"
"fmt"
"strings"
"time"
"google.golang.org/api/dns/v1"
)
type RecordSetPage struct {
Err error
PageNumber int64 `json:"page_number"`
RecordSets []*dns.ResourceRecordSet `json:"record_sets,omitempty"`
}
type RecordSetRequest struct {
Project string `json:"project"`
Zone string `json:"zone"`
// DomainName if set restricts listing to only
// return records with this fully qualified domain name.
DomainName string `json:"domain_name"`
MaxPages int64 `json:"max_pages"`
ResultsPerPage int64 `json:"results_per_page"`
}
type RecordSetPagesResponse struct {
Pages <-chan *RecordSetPage
Cancel func() error
}
func (rreq *RecordSetRequest) Validate() error {
if rreq == nil || rreq.Project == "" {
return errEmptyProject
}
if rreq.Zone == "" {
return errEmptyZone
}
return nil
}
func (c *Client) recordSetsService() *dns.ResourceRecordSetsService {
return dns.NewResourceRecordSetsService(c.dnsSrvc)
}
func (c *Client) ListDNSRecordSets(ctx context.Context, rreq *RecordSetRequest) (*RecordSetPagesResponse, error) {
if err := rreq.Validate(); err != nil {
return nil, err
}
maxPageNumber := rreq.MaxPages
pageExceedsMax := func(pageNumber int64) bool {
if maxPageNumber <= 0 {
return false
}
return pageNumber > maxPageNumber
}
maxResultsPerPage := int64(40)
if rreq.ResultsPerPage > 0 {
maxResultsPerPage = rreq.ResultsPerPage
}
cancelChan, cancelFn := makeCanceler()
pagesChan := make(chan *RecordSetPage)
go func() {
defer close(pagesChan)
dnsLc := c.recordSetsService().List(rreq.Project, rreq.Zone).Context(ctx)
dnsLc.MaxResults(maxResultsPerPage)
if rreq.DomainName != "" {
dnsLc.Name(ensureHasTrailingDot(rreq.DomainName))
}
pageToken := ""
pageNumber := int64(0)
throttleDuration := time.Duration(350 * time.Millisecond)
for {
dnsLc.PageToken(pageToken)
dPage := new(RecordSetPage)
dPage.PageNumber = pageNumber
dRes, err := dnsLc.Do()
if err != nil {
dPage.Err = err
pagesChan <- dPage
return
}
dPage.RecordSets = dRes.Rrsets
pagesChan <- dPage
pageNumber += 1
if pageExceedsMax(pageNumber) {
return
}
pageToken := dRes.NextPageToken
select {
case <-cancelChan:
return
case <-time.After(throttleDuration):
}
if pageToken == "" {
// No more results left
break
}
}
}()
rres := &RecordSetPagesResponse{
Pages: pagesChan,
Cancel: cancelFn,
}
return rres, nil
}
type RecordType string
const (
AAAName RecordType = "AAA"
AName RecordType = "A"
CName RecordType = "CNAME"
CAA RecordType = "CAA"
MX RecordType = "MX"
NS RecordType = "NS"
SPF RecordType = "SPF"
SRV RecordType = "SRV"
TXT RecordType = "TXT"
)
type Record struct {
DNSName string `json:"dns_name"`
TTL int64 `json:"ttl"`
Type RecordType `json:"type"`
IPV4Addresses []string `json:"ipv4_addresses"`
IPV6Addresses []string `json:"ipv6_addresses"`
CanonicalName string `json:"canonical_name"`
NameServers []string `json:"name_servers"`
CertificateAuthorityAuthorizations []string `json:"certificate_authority_authorizations"`
PreferenceAndMailServers []string `json:"preference_and_mail_servers"`
SPFData []string `json:"spf_data"`
SRVData []string `json:"srv_data"`
TXTRecords []string `json:"txt_records"`
}
func ensureHasTrailingDot(s string) string {
if !strings.HasSuffix(s, ".") {
s = s + "."
}
return s
}
func (r *Record) toRecordSet() *dns.ResourceRecordSet {
rrset := &dns.ResourceRecordSet{
// DNSNames without trailing dots are rejected as
// invalid so ensure that they do have them.
Name: ensureHasTrailingDot(r.DNSName),
Type: string(r.Type),
Ttl: r.TTL,
}
if r.CanonicalName != "" {
rrset.Rrdatas = append(rrset.Rrdatas, ensureHasTrailingDot(r.CanonicalName))
}
rrset.Rrdatas = append(rrset.Rrdatas, r.CertificateAuthorityAuthorizations...)
rrset.Rrdatas = append(rrset.Rrdatas, r.IPV4Addresses...)
rrset.Rrdatas = append(rrset.Rrdatas, r.IPV6Addresses...)
rrset.Rrdatas = append(rrset.Rrdatas, r.NameServers...)
rrset.Rrdatas = append(rrset.Rrdatas, r.PreferenceAndMailServers...)
rrset.Rrdatas = append(rrset.Rrdatas, r.SPFData...)
rrset.Rrdatas = append(rrset.Rrdatas, r.SRVData...)
rrset.Rrdatas = append(rrset.Rrdatas, r.TXTRecords...)
return rrset
}
type UpdateRequest struct {
Zone string `json:"zone"`
Project string `json:"project"`
Records []*Record `json:"records"`
Additions []*Record `json:"additions"`
Deletions []*Record `json:"deletions"`
}
var (
errBlankCanonicalName = errors.New("expecting a non-blank canonical name")
errEmptyIPV4Addresses = errors.New("expecting at least one IPV4 address")
errEmptyIPV6Addresses = errors.New("expecting at least one IPV6 address")
errEmptyCertificateAuthorityAuthorizations = errors.New("expecting at least one certificate authority authorization")
errEmptySPFData = errors.New("expecting at least one SPF record")
errEmptySRVData = errors.New("expecting at least one SRV record")
errEmptyTXTRecords = errors.New("expecting at least one TXT record")
errEmptyNameServers = errors.New("expecting at least one name server")
errEmptyPreferenceAndMailServers = errors.New("expecting at least one preferenceAndMailServer")
errBlankUpdateRequest = errors.New("expecting a non-blank updateRequest")
)
func (r *Record) validateForAAAName() error {
uniqIPV6Addresses := dedup(r.IPV6Addresses...)
if len(uniqIPV6Addresses) == 0 {
return errEmptyIPV6Addresses
}
r.IPV6Addresses = uniqIPV6Addresses
return nil
}
func (r *Record) validateForSPF() error {
uniqs := dedup(r.SPFData...)
if len(uniqs) == 0 {
return errEmptySPFData
}
r.SPFData = uniqs
return nil
}
func (r *Record) validateForTXT() error {
uniqs := dedup(r.TXTRecords...)
if len(uniqs) == 0 {
return errEmptyTXTRecords
}
r.TXTRecords = uniqs
return nil
}
func (r *Record) validateForSRV() error {
uniqs := dedup(r.SRVData...)
if len(uniqs) == 0 {
return errEmptySPFData
}
r.SRVData = uniqs
return nil
}
func (r *Record) validateForNS() error {
uniqs := dedup(r.NameServers...)
if len(uniqs) == 0 {
return errEmptyNameServers
}
r.NameServers = uniqs
return nil
}
func (r *Record) validateForMX() error {
uniqs := dedup(r.PreferenceAndMailServers...)
if len(uniqs) == 0 {
return errEmptyPreferenceAndMailServers
}
r.PreferenceAndMailServers = uniqs
return nil
}
func (r *Record) validateForAName() error {
uniqIPV4Addresses := dedup(r.IPV4Addresses...)
if len(uniqIPV4Addresses) == 0 {
return errEmptyIPV4Addresses
}
r.IPV4Addresses = uniqIPV4Addresses
return nil
}
func (r *Record) validateForCName() error {
if strings.TrimSpace(r.CanonicalName) == "" {
return errBlankCanonicalName
}
return nil
}
func (r *Record) validateForCAA() error {
uniqs := dedup(r.CertificateAuthorityAuthorizations...)
if len(uniqs) == 0 {
return errEmptyCertificateAuthorityAuthorizations
}
r.CertificateAuthorityAuthorizations = uniqs
return nil
}
func dedup(items ...string) []string {
var uniqRecords []string
seen := make(map[string]bool)
for _, item := range items {
if _, known := seen[item]; known {
continue
}
trimmedItem := strings.TrimSpace(item)
if trimmedItem == "" {
continue
}
seen[item] = true
seen[trimmedItem] = true
uniqRecords = append(uniqRecords, trimmedItem)
}
return uniqRecords
}
func (r *Record) Validate() error {
switch r.Type {
default:
return fmt.Errorf("unknown recordType: %q", r.Type)
case AAAName:
return r.validateForAAAName()
case AName:
return r.validateForAName()
case CAA:
return r.validateForCAA()
case CName:
return r.validateForCName()
case MX:
return r.validateForMX()
case NS:
return r.validateForNS()
case SPF:
return r.validateForSPF()
case SRV:
return r.validateForSRV()
case TXT:
return r.validateForTXT()
}
}
func (ureq *UpdateRequest) validate() error {
if ureq == nil || ureq.Zone == "" {
return errBlankZone
}
if ureq.Project == "" {
return errBlankProject
}
return nil
}
func (c *Client) UpdateRecordSets(ctx context.Context, ureq *UpdateRequest) (*dns.Change, error) {
if err := ureq.validate(); err != nil {
return nil, err
}
deletions, err := toRecordSets(ureq.Deletions...)
if err != nil {
return nil, err
}
additions, err := toRecordSets(ureq.Additions...)
if err != nil {
return nil, err
}
change := &dns.Change{
Additions: additions,
Deletions: deletions,
}
cl := c.changesService().Create(ureq.Project, ureq.Zone, change).Context(ctx)
return cl.Do()
}
func (c *Client) AddRecordSets(ctx context.Context, areq *UpdateRequest) (*dns.Change, error) {
if areq == nil {
return nil, errBlankUpdateRequest
}
return c.UpdateRecordSets(ctx, &UpdateRequest{
Zone: areq.Zone,
Project: areq.Project,
Additions: areq.Records[:],
})
}
func (c *Client) DeleteRecordSets(ctx context.Context, dreq *UpdateRequest) (*dns.Change, error) {
if dreq == nil {
return nil, errBlankUpdateRequest
}
return c.UpdateRecordSets(ctx, &UpdateRequest{
Zone: dreq.Zone,
Project: dreq.Project,
Deletions: dreq.Records[:],
})
}
func toRecordSets(records ...*Record) ([]*dns.ResourceRecordSet, error) {
var rrsets []*dns.ResourceRecordSet
for _, rec := range records {
if err := rec.Validate(); err != nil {
return nil, err
}
rrsets = append(rrsets, rec.toRecordSet())
}
return rrsets, nil
}
func (c *Client) changesService() *dns.ChangesService {
return dns.NewChangesService(c.dnsSrvc)
}