508 lines
15 KiB
Go
508 lines
15 KiB
Go
package dnsfilter
|
|
|
|
import (
|
|
"bufio"
|
|
"errors"
|
|
"fmt"
|
|
"log"
|
|
"net"
|
|
"os"
|
|
"strconv"
|
|
"strings"
|
|
"sync"
|
|
"time"
|
|
|
|
"github.com/coredns/coredns/core/dnsserver"
|
|
"github.com/coredns/coredns/plugin"
|
|
"github.com/coredns/coredns/plugin/metrics"
|
|
"github.com/coredns/coredns/plugin/pkg/dnstest"
|
|
"github.com/coredns/coredns/plugin/pkg/upstream"
|
|
"github.com/coredns/coredns/request"
|
|
|
|
"github.com/mholt/caddy"
|
|
|
|
"github.com/miekg/dns"
|
|
|
|
"github.com/prometheus/client_golang/prometheus"
|
|
|
|
"github.com/AdguardTeam/AdguardDNS/dnsfilter"
|
|
"golang.org/x/net/context"
|
|
)
|
|
|
|
var defaultSOA = &dns.SOA{
|
|
// values copied from verisign's nonexistent .com domain
|
|
// their exact values are not important in our use case because they are used for domain transfers between primary/secondary DNS servers
|
|
Refresh: 1800,
|
|
Retry: 900,
|
|
Expire: 604800,
|
|
Minttl: 86400,
|
|
}
|
|
|
|
func init() {
|
|
caddy.RegisterPlugin("dnsfilter", caddy.Plugin{
|
|
ServerType: "dns",
|
|
Action: setup,
|
|
})
|
|
}
|
|
|
|
type Plugin struct {
|
|
d *dnsfilter.Dnsfilter
|
|
Next plugin.Handler
|
|
upstream upstream.Upstream
|
|
hosts map[string]net.IP
|
|
|
|
SafeBrowsingBlockHost string
|
|
ParentalBlockHost string
|
|
QueryLogEnabled bool
|
|
}
|
|
|
|
var defaultPlugin = Plugin{
|
|
SafeBrowsingBlockHost: "safebrowsing.block.dns.adguard.com",
|
|
ParentalBlockHost: "family.block.dns.adguard.com",
|
|
}
|
|
|
|
func newDnsCounter(name string, help string) prometheus.Counter {
|
|
return prometheus.NewCounter(prometheus.CounterOpts{
|
|
Namespace: plugin.Namespace,
|
|
Subsystem: "dnsfilter",
|
|
Name: name,
|
|
Help: help,
|
|
})
|
|
}
|
|
|
|
var (
|
|
requests = newDnsCounter("requests_total", "Count of requests seen by dnsfilter.")
|
|
filtered = newDnsCounter("filtered_total", "Count of requests filtered by dnsfilter.")
|
|
filteredLists = newDnsCounter("filtered_lists_total", "Count of requests filtered by dnsfilter using lists.")
|
|
filteredSafebrowsing = newDnsCounter("filtered_safebrowsing_total", "Count of requests filtered by dnsfilter using safebrowsing.")
|
|
filteredParental = newDnsCounter("filtered_parental_total", "Count of requests filtered by dnsfilter using parental.")
|
|
filteredInvalid = newDnsCounter("filtered_invalid_total", "Count of requests filtered by dnsfilter because they were invalid.")
|
|
whitelisted = newDnsCounter("whitelisted_total", "Count of requests not filtered by dnsfilter because they are whitelisted.")
|
|
safesearch = newDnsCounter("safesearch_total", "Count of requests replaced by dnsfilter safesearch.")
|
|
errorsTotal = newDnsCounter("errors_total", "Count of requests that dnsfilter couldn't process because of transitive errors.")
|
|
)
|
|
|
|
//
|
|
// coredns handling functions
|
|
//
|
|
func setupPlugin(c *caddy.Controller) (*Plugin, error) {
|
|
// create new Plugin and copy default values
|
|
var d = new(Plugin)
|
|
*d = defaultPlugin
|
|
d.d = dnsfilter.New()
|
|
d.hosts = make(map[string]net.IP)
|
|
|
|
var filterFileName string
|
|
for c.Next() {
|
|
args := c.RemainingArgs()
|
|
if len(args) == 0 {
|
|
// must have at least one argument
|
|
return nil, c.ArgErr()
|
|
}
|
|
filterFileName = args[0]
|
|
for c.NextBlock() {
|
|
switch c.Val() {
|
|
case "safebrowsing":
|
|
d.d.EnableSafeBrowsing()
|
|
if c.NextArg() {
|
|
if len(c.Val()) == 0 {
|
|
return nil, c.ArgErr()
|
|
}
|
|
d.d.SetSafeBrowsingServer(c.Val())
|
|
}
|
|
case "safesearch":
|
|
d.d.EnableSafeSearch()
|
|
case "parental":
|
|
if !c.NextArg() {
|
|
return nil, c.ArgErr()
|
|
}
|
|
sensitivity, err := strconv.Atoi(c.Val())
|
|
if err != nil {
|
|
return nil, c.ArgErr()
|
|
}
|
|
err = d.d.EnableParental(sensitivity)
|
|
if err != nil {
|
|
return nil, c.ArgErr()
|
|
}
|
|
if c.NextArg() {
|
|
if len(c.Val()) == 0 {
|
|
return nil, c.ArgErr()
|
|
}
|
|
d.ParentalBlockHost = c.Val()
|
|
}
|
|
case "querylog":
|
|
d.QueryLogEnabled = true
|
|
onceQueryLog.Do(func() {
|
|
go startQueryLogServer() // TODO: how to handle errors?
|
|
})
|
|
}
|
|
}
|
|
}
|
|
|
|
file, err := os.Open(filterFileName)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer file.Close()
|
|
|
|
count := 0
|
|
scanner := bufio.NewScanner(file)
|
|
for scanner.Scan() {
|
|
text := scanner.Text()
|
|
if d.parseEtcHosts(text) {
|
|
continue
|
|
}
|
|
err = d.d.AddRule(text, 0)
|
|
if err == dnsfilter.ErrInvalidSyntax {
|
|
continue
|
|
}
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
count++
|
|
}
|
|
log.Printf("Added %d rules from %s", count, filterFileName)
|
|
|
|
if err = scanner.Err(); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
d.upstream, err = upstream.New(nil)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return d, nil
|
|
}
|
|
|
|
func setup(c *caddy.Controller) error {
|
|
d, err := setupPlugin(c)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
config := dnsserver.GetConfig(c)
|
|
config.AddPlugin(func(next plugin.Handler) plugin.Handler {
|
|
d.Next = next
|
|
return d
|
|
})
|
|
|
|
c.OnStartup(func() error {
|
|
m := dnsserver.GetConfig(c).Handler("prometheus")
|
|
if m == nil {
|
|
return nil
|
|
}
|
|
if x, ok := m.(*metrics.Metrics); ok {
|
|
x.MustRegister(requests)
|
|
x.MustRegister(filtered)
|
|
x.MustRegister(filteredLists)
|
|
x.MustRegister(filteredSafebrowsing)
|
|
x.MustRegister(filteredParental)
|
|
x.MustRegister(whitelisted)
|
|
x.MustRegister(safesearch)
|
|
x.MustRegister(errorsTotal)
|
|
x.MustRegister(d)
|
|
}
|
|
return nil
|
|
})
|
|
c.OnShutdown(d.OnShutdown)
|
|
|
|
return nil
|
|
}
|
|
|
|
func (d *Plugin) parseEtcHosts(text string) bool {
|
|
if pos := strings.IndexByte(text, '#'); pos != -1 {
|
|
text = text[0:pos]
|
|
}
|
|
fields := strings.Fields(text)
|
|
if len(fields) < 2 {
|
|
return false
|
|
}
|
|
addr := net.ParseIP(fields[0])
|
|
if addr == nil {
|
|
return false
|
|
}
|
|
for _, host := range fields[1:] {
|
|
if val, ok := d.hosts[host]; ok {
|
|
log.Printf("warning: host %s already has value %s, will overwrite it with %s", host, val, addr)
|
|
}
|
|
d.hosts[host] = addr
|
|
}
|
|
return true
|
|
}
|
|
|
|
func (d *Plugin) OnShutdown() error {
|
|
d.d.Destroy()
|
|
d.d = nil
|
|
return nil
|
|
}
|
|
|
|
type statsFunc func(ch interface{}, name string, text string, value float64, valueType prometheus.ValueType)
|
|
|
|
func doDesc(ch interface{}, name string, text string, value float64, valueType prometheus.ValueType) {
|
|
realch, ok := ch.(chan<- *prometheus.Desc)
|
|
if ok == false {
|
|
log.Printf("Couldn't convert ch to chan<- *prometheus.Desc\n")
|
|
return
|
|
}
|
|
realch <- prometheus.NewDesc(name, text, nil, nil)
|
|
}
|
|
|
|
func doMetric(ch interface{}, name string, text string, value float64, valueType prometheus.ValueType) {
|
|
realch, ok := ch.(chan<- prometheus.Metric)
|
|
if ok == false {
|
|
log.Printf("Couldn't convert ch to chan<- prometheus.Metric\n")
|
|
return
|
|
}
|
|
desc := prometheus.NewDesc(name, text, nil, nil)
|
|
realch <- prometheus.MustNewConstMetric(desc, valueType, value)
|
|
}
|
|
|
|
func gen(ch interface{}, doFunc statsFunc, name string, text string, value float64, valueType prometheus.ValueType) {
|
|
doFunc(ch, name, text, value, valueType)
|
|
}
|
|
|
|
func doStatsLookup(ch interface{}, doFunc statsFunc, name string, lookupstats *dnsfilter.LookupStats) {
|
|
gen(ch, doFunc, fmt.Sprintf("coredns_dnsfilter_%s_requests", name), fmt.Sprintf("Number of %s HTTP requests that were sent", name), float64(lookupstats.Requests), prometheus.CounterValue)
|
|
gen(ch, doFunc, fmt.Sprintf("coredns_dnsfilter_%s_cachehits", name), fmt.Sprintf("Number of %s lookups that didn't need HTTP requests", name), float64(lookupstats.CacheHits), prometheus.CounterValue)
|
|
gen(ch, doFunc, fmt.Sprintf("coredns_dnsfilter_%s_pending", name), fmt.Sprintf("Number of currently pending %s HTTP requests", name), float64(lookupstats.Pending), prometheus.GaugeValue)
|
|
gen(ch, doFunc, fmt.Sprintf("coredns_dnsfilter_%s_pending_max", name), fmt.Sprintf("Maximum number of pending %s HTTP requests", name), float64(lookupstats.PendingMax), prometheus.GaugeValue)
|
|
}
|
|
|
|
func (d *Plugin) doStats(ch interface{}, doFunc statsFunc) {
|
|
stats := d.d.GetStats()
|
|
doStatsLookup(ch, doFunc, "safebrowsing", &stats.Safebrowsing)
|
|
doStatsLookup(ch, doFunc, "parental", &stats.Parental)
|
|
}
|
|
|
|
func (d *Plugin) Describe(ch chan<- *prometheus.Desc) {
|
|
d.doStats(ch, doDesc)
|
|
}
|
|
|
|
func (d *Plugin) Collect(ch chan<- prometheus.Metric) {
|
|
d.doStats(ch, doMetric)
|
|
}
|
|
|
|
func (d *Plugin) replaceHostWithValAndReply(ctx context.Context, w dns.ResponseWriter, r *dns.Msg, host string, val string, question dns.Question) (int, error) {
|
|
// check if it's a domain name or IP address
|
|
addr := net.ParseIP(val)
|
|
var records []dns.RR
|
|
log.Println("Will give", val, "instead of", host)
|
|
if addr != nil {
|
|
// this is an IP address, return it
|
|
result, err := dns.NewRR(host + " A " + val)
|
|
if err != nil {
|
|
log.Printf("Got error %s\n", err)
|
|
return dns.RcodeServerFailure, fmt.Errorf("plugin/dnsfilter: %s", err)
|
|
}
|
|
records = append(records, result)
|
|
} else {
|
|
// this is a domain name, need to look it up
|
|
req := new(dns.Msg)
|
|
req.SetQuestion(dns.Fqdn(val), question.Qtype)
|
|
req.RecursionDesired = true
|
|
reqstate := request.Request{W: w, Req: req, Context: ctx}
|
|
result, err := d.upstream.Lookup(reqstate, dns.Fqdn(val), reqstate.QType())
|
|
if err != nil {
|
|
log.Printf("Got error %s\n", err)
|
|
return dns.RcodeServerFailure, fmt.Errorf("plugin/dnsfilter: %s", err)
|
|
}
|
|
if result != nil {
|
|
for _, answer := range result.Answer {
|
|
answer.Header().Name = question.Name
|
|
}
|
|
records = result.Answer
|
|
}
|
|
}
|
|
m := new(dns.Msg)
|
|
m.SetReply(r)
|
|
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
|
|
m.Answer = append(m.Answer, records...)
|
|
state := request.Request{W: w, Req: r, Context: ctx}
|
|
state.SizeAndDo(m)
|
|
err := state.W.WriteMsg(m)
|
|
if err != nil {
|
|
log.Printf("Got error %s\n", err)
|
|
return dns.RcodeServerFailure, fmt.Errorf("plugin/dnsfilter: %s", err)
|
|
}
|
|
return dns.RcodeSuccess, nil
|
|
}
|
|
|
|
// generate SOA record that makes DNS clients cache NXdomain results
|
|
// the only value that is important is TTL in header, other values like refresh, retry, expire and minttl are irrelevant
|
|
func genSOA(r *dns.Msg) []dns.RR {
|
|
zone := r.Question[0].Name
|
|
header := dns.RR_Header{Name: zone, Rrtype: dns.TypeSOA, Ttl: 3600, Class: dns.ClassINET}
|
|
|
|
Mbox := "hostmaster."
|
|
if zone[0] != '.' {
|
|
Mbox += zone
|
|
}
|
|
Ns := "fake-for-negative-caching.adguard.com."
|
|
|
|
soa := defaultSOA
|
|
soa.Hdr = header
|
|
soa.Mbox = Mbox
|
|
soa.Ns = Ns
|
|
soa.Serial = uint32(time.Now().Unix())
|
|
return []dns.RR{soa}
|
|
}
|
|
|
|
func writeNXdomain(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
|
|
state := request.Request{W: w, Req: r, Context: ctx}
|
|
m := new(dns.Msg)
|
|
m.SetRcode(state.Req, dns.RcodeNameError)
|
|
m.Authoritative, m.RecursionAvailable, m.Compress = true, true, true
|
|
m.Ns = genSOA(r)
|
|
|
|
state.SizeAndDo(m)
|
|
err := state.W.WriteMsg(m)
|
|
if err != nil {
|
|
log.Printf("Got error %s\n", err)
|
|
return dns.RcodeServerFailure, err
|
|
}
|
|
return dns.RcodeNameError, nil
|
|
}
|
|
|
|
func (d *Plugin) serveDNSInternal(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error, dnsfilter.Result) {
|
|
if len(r.Question) != 1 {
|
|
// google DNS, bind and others do the same
|
|
return dns.RcodeFormatError, fmt.Errorf("Got DNS request with != 1 questions"), dnsfilter.Result{}
|
|
}
|
|
for _, question := range r.Question {
|
|
host := strings.ToLower(strings.TrimSuffix(question.Name, "."))
|
|
// is it a safesearch domain?
|
|
if val, ok := d.d.SafeSearchDomain(host); ok {
|
|
rcode, err := d.replaceHostWithValAndReply(ctx, w, r, host, val, question)
|
|
if err != nil {
|
|
return rcode, err, dnsfilter.Result{}
|
|
}
|
|
return rcode, err, dnsfilter.Result{Reason: dnsfilter.FilteredSafeSearch}
|
|
}
|
|
|
|
// is it in hosts?
|
|
if val, ok := d.hosts[host]; ok {
|
|
// it is, if it's a loopback host, reply with NXDOMAIN
|
|
if val.IsLoopback() {
|
|
rcode, err := writeNXdomain(ctx, w, r)
|
|
if err != nil {
|
|
return rcode, err, dnsfilter.Result{}
|
|
}
|
|
return rcode, err, dnsfilter.Result{Reason: dnsfilter.FilteredInvalid}
|
|
}
|
|
// it's not a loopback host, replace it with value specified
|
|
rcode, err := d.replaceHostWithValAndReply(ctx, w, r, host, val.String(), question)
|
|
if err != nil {
|
|
return rcode, err, dnsfilter.Result{}
|
|
}
|
|
return rcode, err, dnsfilter.Result{Reason: dnsfilter.FilteredSafeSearch}
|
|
}
|
|
|
|
// needs to be filtered instead
|
|
result, err := d.d.CheckHost(host)
|
|
if err != nil {
|
|
log.Printf("plugin/dnsfilter: %s\n", err)
|
|
return dns.RcodeServerFailure, fmt.Errorf("plugin/dnsfilter: %s", err), dnsfilter.Result{}
|
|
}
|
|
|
|
if result.IsFiltered {
|
|
switch result.Reason {
|
|
case dnsfilter.FilteredSafeBrowsing:
|
|
// return cname safebrowsing.block.dns.adguard.com
|
|
val := d.SafeBrowsingBlockHost
|
|
rcode, err := d.replaceHostWithValAndReply(ctx, w, r, host, val, question)
|
|
if err != nil {
|
|
return rcode, err, dnsfilter.Result{}
|
|
}
|
|
return rcode, err, result
|
|
case dnsfilter.FilteredParental:
|
|
// return cname family.block.dns.adguard.com
|
|
val := d.ParentalBlockHost
|
|
rcode, err := d.replaceHostWithValAndReply(ctx, w, r, host, val, question)
|
|
if err != nil {
|
|
return rcode, err, dnsfilter.Result{}
|
|
}
|
|
return rcode, err, result
|
|
case dnsfilter.FilteredBlackList:
|
|
// return NXdomain
|
|
rcode, err := writeNXdomain(ctx, w, r)
|
|
if err != nil {
|
|
return rcode, err, dnsfilter.Result{}
|
|
}
|
|
return rcode, err, result
|
|
default:
|
|
log.Printf("SHOULD NOT HAPPEN -- got unknown reason for filtering: %T %v %s", result.Reason, result.Reason, result.Reason.String())
|
|
}
|
|
} else {
|
|
switch result.Reason {
|
|
case dnsfilter.NotFilteredWhiteList:
|
|
rcode, err := plugin.NextOrFailure(d.Name(), d.Next, ctx, w, r)
|
|
return rcode, err, result
|
|
case dnsfilter.NotFilteredNotFound:
|
|
// do nothing, pass through to lower code
|
|
default:
|
|
log.Printf("SHOULD NOT HAPPEN -- got unknown reason for not filtering: %T %v %s", result.Reason, result.Reason, result.Reason.String())
|
|
}
|
|
}
|
|
}
|
|
rcode, err := plugin.NextOrFailure(d.Name(), d.Next, ctx, w, r)
|
|
return rcode, err, dnsfilter.Result{}
|
|
}
|
|
|
|
func (d *Plugin) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
|
|
start := time.Now()
|
|
requests.Inc()
|
|
state := request.Request{W: w, Req: r}
|
|
ip := state.IP()
|
|
|
|
// capture the written answer
|
|
rrw := dnstest.NewRecorder(w)
|
|
rcode, err, result := d.serveDNSInternal(ctx, rrw, r)
|
|
if rcode > 0 {
|
|
// actually send the answer if we have one
|
|
answer := new(dns.Msg)
|
|
answer.SetRcode(r, rcode)
|
|
state.SizeAndDo(answer)
|
|
w.WriteMsg(answer)
|
|
}
|
|
|
|
// increment counters
|
|
switch {
|
|
case err != nil:
|
|
errorsTotal.Inc()
|
|
case result.Reason == dnsfilter.FilteredBlackList:
|
|
filtered.Inc()
|
|
filteredLists.Inc()
|
|
case result.Reason == dnsfilter.FilteredSafeBrowsing:
|
|
filtered.Inc()
|
|
filteredSafebrowsing.Inc()
|
|
case result.Reason == dnsfilter.FilteredParental:
|
|
filtered.Inc()
|
|
filteredParental.Inc()
|
|
case result.Reason == dnsfilter.FilteredInvalid:
|
|
filtered.Inc()
|
|
filteredInvalid.Inc()
|
|
case result.Reason == dnsfilter.FilteredSafeSearch:
|
|
// the request was passsed through but not filtered, don't increment filtered
|
|
safesearch.Inc()
|
|
case result.Reason == dnsfilter.NotFilteredWhiteList:
|
|
whitelisted.Inc()
|
|
case result.Reason == dnsfilter.NotFilteredNotFound:
|
|
// do nothing
|
|
case result.Reason == dnsfilter.NotFilteredError:
|
|
text := "SHOULD NOT HAPPEN: got DNSFILTER_NOTFILTERED_ERROR without err != nil!"
|
|
log.Println(text)
|
|
err = errors.New(text)
|
|
rcode = dns.RcodeServerFailure
|
|
}
|
|
|
|
// log
|
|
if d.QueryLogEnabled {
|
|
logRequest(r, rrw.Msg, result, time.Since(start), ip)
|
|
}
|
|
return rcode, err
|
|
}
|
|
|
|
func (d *Plugin) Name() string { return "dnsfilter" }
|
|
|
|
var onceQueryLog sync.Once
|