/
route53.go
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/
route53.go
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// Package route53 implements a plugin that returns resource records
// from AWS route53.
package route53
import (
"context"
"errors"
"fmt"
"strconv"
"strings"
"sync"
"time"
"github.com/inverse-inc/wireguard-go/dns/plugin"
"github.com/inverse-inc/wireguard-go/dns/plugin/file"
"github.com/inverse-inc/wireguard-go/dns/plugin/pkg/fall"
"github.com/inverse-inc/wireguard-go/dns/plugin/pkg/upstream"
"github.com/inverse-inc/wireguard-go/dns/request"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/service/route53"
"github.com/aws/aws-sdk-go/service/route53/route53iface"
"github.com/miekg/dns"
)
// Route53 is a plugin that returns RR from AWS route53.
type Route53 struct {
Next plugin.Handler
Fall fall.F
zoneNames []string
client route53iface.Route53API
upstream *upstream.Upstream
refresh time.Duration
zMu sync.RWMutex
zones zones
}
type zone struct {
id string
z *file.Zone
dns string
}
type zones map[string][]*zone
// New reads from the keys map which uses domain names as its key and hosted
// zone id lists as its values, validates that each domain name/zone id pair
// does exist, and returns a new *Route53. In addition to this, upstream is use
// for doing recursive queries against CNAMEs. Returns error if it cannot
// verify any given domain name/zone id pair.
func New(ctx context.Context, c route53iface.Route53API, keys map[string][]string, refresh time.Duration) (*Route53, error) {
zones := make(map[string][]*zone, len(keys))
zoneNames := make([]string, 0, len(keys))
for dns, hostedZoneIDs := range keys {
for _, hostedZoneID := range hostedZoneIDs {
_, err := c.ListHostedZonesByNameWithContext(ctx, &route53.ListHostedZonesByNameInput{
DNSName: aws.String(dns),
HostedZoneId: aws.String(hostedZoneID),
})
if err != nil {
return nil, err
}
if _, ok := zones[dns]; !ok {
zoneNames = append(zoneNames, dns)
}
zones[dns] = append(zones[dns], &zone{id: hostedZoneID, dns: dns, z: file.NewZone(dns, "")})
}
}
return &Route53{
client: c,
zoneNames: zoneNames,
zones: zones,
upstream: upstream.New(),
refresh: refresh,
}, nil
}
// Run executes first update, spins up an update forever-loop.
// Returns error if first update fails.
func (h *Route53) Run(ctx context.Context) error {
if err := h.updateZones(ctx); err != nil {
return err
}
go func() {
for {
select {
case <-ctx.Done():
log.Infof("Breaking out of Route53 update loop: %v", ctx.Err())
return
case <-time.After(h.refresh):
if err := h.updateZones(ctx); err != nil && ctx.Err() == nil /* Don't log error if ctx expired. */ {
log.Errorf("Failed to update zones: %v", err)
}
}
}
}()
return nil
}
// ServeDNS implements the plugin.Handler.ServeDNS.
func (h *Route53) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
state := request.Request{W: w, Req: r}
qname := state.Name()
zName := plugin.Zones(h.zoneNames).Matches(qname)
if zName == "" {
return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
}
z, ok := h.zones[zName]
if !ok || z == nil {
return dns.RcodeServerFailure, nil
}
m := new(dns.Msg)
m.SetReply(r)
m.Authoritative = true
var result file.Result
for _, hostedZone := range z {
h.zMu.RLock()
m.Answer, m.Ns, m.Extra, result = hostedZone.z.Lookup(ctx, state, qname)
h.zMu.RUnlock()
// Take the answer if it's non-empty OR if there is another
// record type exists for this name (NODATA).
if len(m.Answer) != 0 || result == file.NoData {
break
}
}
if len(m.Answer) == 0 && result != file.NoData && h.Fall.Through(qname) {
return plugin.NextOrFailure(h.Name(), h.Next, ctx, w, r)
}
switch result {
case file.Success:
case file.NoData:
case file.NameError:
m.Rcode = dns.RcodeNameError
case file.Delegation:
m.Authoritative = false
case file.ServerFailure:
return dns.RcodeServerFailure, nil
}
w.WriteMsg(m)
return dns.RcodeSuccess, nil
}
const escapeSeq = "\\"
// maybeUnescape parses s and converts escaped ASCII codepoints (in octal) back
// to its ASCII representation.
//
// From AWS docs:
//
// "If the domain name includes any characters other than a to z, 0 to 9, -
// (hyphen), or _ (underscore), Route 53 API actions return the characters as
// escape codes."
//
// For our purposes (and with respect to RFC 1035), we'll fish for a-z, 0-9,
// '-', '.' and '*' as the leftmost character (for wildcards) and throw error
// for everything else.
//
// Example:
// `\\052.example.com.` -> `*.example.com`
// `\\137.example.com.` -> error ('_' is not valid)
func maybeUnescape(s string) (string, error) {
var out string
for {
i := strings.Index(s, escapeSeq)
if i < 0 {
return out + s, nil
}
out += s[:i]
li, ri := i+len(escapeSeq), i+len(escapeSeq)+3
if ri > len(s) {
return "", fmt.Errorf("invalid escape sequence: '%s%s'", escapeSeq, s[li:])
}
// Parse `\\xxx` in base 8 (2nd arg) and attempt to fit into
// 8-bit result (3rd arg).
n, err := strconv.ParseInt(s[li:ri], 8, 8)
if err != nil {
return "", fmt.Errorf("invalid escape sequence: '%s%s'", escapeSeq, s[li:ri])
}
r := rune(n)
switch {
case r >= rune('a') && r <= rune('z'): // Route53 converts everything to lowercase.
case r >= rune('0') && r <= rune('9'):
case r == rune('*'):
if out != "" {
return "", errors.New("`*' only supported as wildcard (leftmost label)")
}
case r == rune('-'):
case r == rune('.'):
default:
return "", fmt.Errorf("invalid character: %s%#03o", escapeSeq, r)
}
out += string(r)
s = s[i+len(escapeSeq)+3:]
}
}
func updateZoneFromRRS(rrs *route53.ResourceRecordSet, z *file.Zone) error {
for _, rr := range rrs.ResourceRecords {
n, err := maybeUnescape(aws.StringValue(rrs.Name))
if err != nil {
return fmt.Errorf("failed to unescape `%s' name: %v", aws.StringValue(rrs.Name), err)
}
v, err := maybeUnescape(aws.StringValue(rr.Value))
if err != nil {
return fmt.Errorf("failed to unescape `%s' value: %v", aws.StringValue(rr.Value), err)
}
// Assemble RFC 1035 conforming record to pass into dns scanner.
rfc1035 := fmt.Sprintf("%s %d IN %s %s", n, aws.Int64Value(rrs.TTL), aws.StringValue(rrs.Type), v)
r, err := dns.NewRR(rfc1035)
if err != nil {
return fmt.Errorf("failed to parse resource record: %v", err)
}
z.Insert(r)
}
return nil
}
// updateZones re-queries resource record sets for each zone and updates the
// zone object.
// Returns error if any zones error'ed out, but waits for other zones to
// complete first.
func (h *Route53) updateZones(ctx context.Context) error {
errc := make(chan error)
defer close(errc)
for zName, z := range h.zones {
go func(zName string, z []*zone) {
var err error
defer func() {
errc <- err
}()
for i, hostedZone := range z {
newZ := file.NewZone(zName, "")
newZ.Upstream = h.upstream
in := &route53.ListResourceRecordSetsInput{
HostedZoneId: aws.String(hostedZone.id),
MaxItems: aws.String("1000"),
}
err = h.client.ListResourceRecordSetsPagesWithContext(ctx, in,
func(out *route53.ListResourceRecordSetsOutput, last bool) bool {
for _, rrs := range out.ResourceRecordSets {
if err := updateZoneFromRRS(rrs, newZ); err != nil {
// Maybe unsupported record type. Log and carry on.
log.Warningf("Failed to process resource record set: %v", err)
}
}
return true
})
if err != nil {
err = fmt.Errorf("failed to list resource records for %v:%v from route53: %v", zName, hostedZone.id, err)
return
}
h.zMu.Lock()
(*z[i]).z = newZ
h.zMu.Unlock()
}
}(zName, z)
}
// Collect errors (if any). This will also sync on all zones updates
// completion.
var errs []string
for i := 0; i < len(h.zones); i++ {
err := <-errc
if err != nil {
errs = append(errs, err.Error())
}
}
if len(errs) != 0 {
return fmt.Errorf("errors updating zones: %v", errs)
}
return nil
}
// Name implements plugin.Handler.Name.
func (h *Route53) Name() string { return "route53" }