559 lines
16 KiB
Go
559 lines
16 KiB
Go
package dnsfilter
|
|
|
|
import (
|
|
"bufio"
|
|
"errors"
|
|
"fmt"
|
|
"log"
|
|
"net"
|
|
"os"
|
|
"strconv"
|
|
"strings"
|
|
"sync"
|
|
"time"
|
|
|
|
"github.com/AdguardTeam/AdGuardHome/dnsfilter"
|
|
"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"
|
|
"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 plugFilter struct {
|
|
ID int64
|
|
Path string
|
|
}
|
|
|
|
type plugSettings struct {
|
|
SafeBrowsingBlockHost string
|
|
ParentalBlockHost string
|
|
QueryLogEnabled bool
|
|
BlockedTTL uint32 // in seconds, default 3600
|
|
Filters []plugFilter
|
|
}
|
|
|
|
type plug struct {
|
|
d *dnsfilter.Dnsfilter
|
|
Next plugin.Handler
|
|
upstream upstream.Upstream
|
|
settings plugSettings
|
|
|
|
sync.RWMutex
|
|
}
|
|
|
|
var defaultPluginSettings = plugSettings{
|
|
SafeBrowsingBlockHost: "safebrowsing.block.dns.adguard.com",
|
|
ParentalBlockHost: "family.block.dns.adguard.com",
|
|
BlockedTTL: 3600, // in seconds
|
|
Filters: make([]plugFilter, 0),
|
|
}
|
|
|
|
//
|
|
// coredns handling functions
|
|
//
|
|
func setupPlugin(c *caddy.Controller) (*plug, error) {
|
|
// create new Plugin and copy default values
|
|
p := &plug{
|
|
settings: defaultPluginSettings,
|
|
d: dnsfilter.New(nil),
|
|
}
|
|
|
|
log.Println("Initializing the CoreDNS plugin")
|
|
|
|
for c.Next() {
|
|
for c.NextBlock() {
|
|
blockValue := c.Val()
|
|
switch blockValue {
|
|
case "safebrowsing":
|
|
log.Println("Browsing security service is enabled")
|
|
p.d.SafeBrowsingEnabled = true
|
|
if c.NextArg() {
|
|
if len(c.Val()) == 0 {
|
|
return nil, c.ArgErr()
|
|
}
|
|
p.d.SetSafeBrowsingServer(c.Val())
|
|
}
|
|
case "safesearch":
|
|
log.Println("Safe search is enabled")
|
|
p.d.SafeSearchEnabled = true
|
|
case "parental":
|
|
if !c.NextArg() {
|
|
return nil, c.ArgErr()
|
|
}
|
|
sensitivity, err := strconv.Atoi(c.Val())
|
|
if err != nil {
|
|
return nil, c.ArgErr()
|
|
}
|
|
|
|
log.Println("Parental control is enabled")
|
|
if !dnsfilter.IsParentalSensitivityValid(sensitivity) {
|
|
return nil, dnsfilter.ErrInvalidParental
|
|
}
|
|
p.d.ParentalEnabled = true
|
|
p.d.ParentalSensitivity = sensitivity
|
|
if c.NextArg() {
|
|
if len(c.Val()) == 0 {
|
|
return nil, c.ArgErr()
|
|
}
|
|
p.settings.ParentalBlockHost = c.Val()
|
|
}
|
|
case "blocked_ttl":
|
|
if !c.NextArg() {
|
|
return nil, c.ArgErr()
|
|
}
|
|
blockedTtl, err := strconv.ParseUint(c.Val(), 10, 32)
|
|
if err != nil {
|
|
return nil, c.ArgErr()
|
|
}
|
|
log.Printf("Blocked request TTL is %d", blockedTtl)
|
|
p.settings.BlockedTTL = uint32(blockedTtl)
|
|
case "querylog":
|
|
log.Println("Query log is enabled")
|
|
p.settings.QueryLogEnabled = true
|
|
case "filter":
|
|
if !c.NextArg() {
|
|
return nil, c.ArgErr()
|
|
}
|
|
|
|
filterId, err := strconv.ParseInt(c.Val(), 10, 64)
|
|
if err != nil {
|
|
return nil, c.ArgErr()
|
|
}
|
|
if !c.NextArg() {
|
|
return nil, c.ArgErr()
|
|
}
|
|
filterPath := c.Val()
|
|
|
|
// Initialize filter and add it to the list
|
|
p.settings.Filters = append(p.settings.Filters, plugFilter{
|
|
ID: filterId,
|
|
Path: filterPath,
|
|
})
|
|
}
|
|
}
|
|
}
|
|
|
|
for _, filter := range p.settings.Filters {
|
|
log.Printf("Loading rules from %s", filter.Path)
|
|
|
|
file, err := os.Open(filter.Path)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer file.Close()
|
|
|
|
count := 0
|
|
scanner := bufio.NewScanner(file)
|
|
for scanner.Scan() {
|
|
text := scanner.Text()
|
|
|
|
err = p.d.AddRule(text, filter.ID)
|
|
if err == dnsfilter.ErrAlreadyExists || err == dnsfilter.ErrInvalidSyntax {
|
|
continue
|
|
}
|
|
if err != nil {
|
|
log.Printf("Cannot add rule %s: %s", text, err)
|
|
// Just ignore invalid rules
|
|
continue
|
|
}
|
|
count++
|
|
}
|
|
log.Printf("Added %d rules from filter ID=%d", count, filter.ID)
|
|
|
|
if err = scanner.Err(); err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
log.Printf("Loading stats from querylog")
|
|
err := fillStatsFromQueryLog()
|
|
if err != nil {
|
|
log.Printf("Failed to load stats from querylog: %s", err)
|
|
return nil, err
|
|
}
|
|
|
|
if p.settings.QueryLogEnabled {
|
|
onceQueryLog.Do(func() {
|
|
go periodicQueryLogRotate()
|
|
go periodicHourlyTopRotate()
|
|
go statsRotator()
|
|
})
|
|
}
|
|
|
|
onceHook.Do(func() {
|
|
caddy.RegisterEventHook("dnsfilter-reload", hook)
|
|
})
|
|
|
|
p.upstream, err = upstream.New(nil)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return p, nil
|
|
}
|
|
|
|
func setup(c *caddy.Controller) error {
|
|
p, err := setupPlugin(c)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
config := dnsserver.GetConfig(c)
|
|
config.AddPlugin(func(next plugin.Handler) plugin.Handler {
|
|
p.Next = next
|
|
return p
|
|
})
|
|
|
|
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(elapsedTime)
|
|
x.MustRegister(p)
|
|
}
|
|
return nil
|
|
})
|
|
c.OnShutdown(p.onShutdown)
|
|
c.OnFinalShutdown(p.onFinalShutdown)
|
|
|
|
return nil
|
|
}
|
|
|
|
func (p *plug) onShutdown() error {
|
|
p.Lock()
|
|
p.d.Destroy()
|
|
p.d = nil
|
|
p.Unlock()
|
|
return nil
|
|
}
|
|
|
|
func (p *plug) onFinalShutdown() error {
|
|
logBufferLock.Lock()
|
|
err := flushToFile(logBuffer)
|
|
if err != nil {
|
|
log.Printf("failed to flush to file: %s", err)
|
|
return err
|
|
}
|
|
logBufferLock.Unlock()
|
|
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 {
|
|
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 {
|
|
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 (p *plug) doStats(ch interface{}, doFunc statsFunc) {
|
|
p.RLock()
|
|
stats := p.d.GetStats()
|
|
doStatsLookup(ch, doFunc, "safebrowsing", &stats.Safebrowsing)
|
|
doStatsLookup(ch, doFunc, "parental", &stats.Parental)
|
|
p.RUnlock()
|
|
}
|
|
|
|
// Describe is called by prometheus handler to know stat types
|
|
func (p *plug) Describe(ch chan<- *prometheus.Desc) {
|
|
p.doStats(ch, doDesc)
|
|
}
|
|
|
|
// Collect is called by prometheus handler to collect stats
|
|
func (p *plug) Collect(ch chan<- prometheus.Metric) {
|
|
p.doStats(ch, doMetric)
|
|
}
|
|
|
|
func (p *plug) 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) // debug logging
|
|
if addr != nil {
|
|
// this is an IP address, return it
|
|
result, err := dns.NewRR(fmt.Sprintf("%s %d A %s", host, p.settings.BlockedTTL, 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 := p.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 (p *plug) genSOA(r *dns.Msg) []dns.RR {
|
|
zone := r.Question[0].Name
|
|
header := dns.RR_Header{Name: zone, Rrtype: dns.TypeSOA, Ttl: p.settings.BlockedTTL, 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 = 100500 // faster than uint32(time.Now().Unix())
|
|
return []dns.RR{&soa}
|
|
}
|
|
|
|
func (p *plug) 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 = p.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 (p *plug) serveDNSInternal(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, dnsfilter.Result, error) {
|
|
if len(r.Question) != 1 {
|
|
// google DNS, bind and others do the same
|
|
return dns.RcodeFormatError, dnsfilter.Result{}, fmt.Errorf("got a DNS request with more than one Question")
|
|
}
|
|
for _, question := range r.Question {
|
|
host := strings.ToLower(strings.TrimSuffix(question.Name, "."))
|
|
// is it a safesearch domain?
|
|
p.RLock()
|
|
if val, ok := p.d.SafeSearchDomain(host); ok {
|
|
rcode, err := p.replaceHostWithValAndReply(ctx, w, r, host, val, question)
|
|
if err != nil {
|
|
p.RUnlock()
|
|
return rcode, dnsfilter.Result{}, err
|
|
}
|
|
p.RUnlock()
|
|
return rcode, dnsfilter.Result{Reason: dnsfilter.FilteredSafeSearch}, err
|
|
}
|
|
p.RUnlock()
|
|
|
|
// needs to be filtered instead
|
|
p.RLock()
|
|
result, err := p.d.CheckHost(host)
|
|
if err != nil {
|
|
log.Printf("plugin/dnsfilter: %s\n", err)
|
|
p.RUnlock()
|
|
return dns.RcodeServerFailure, dnsfilter.Result{}, fmt.Errorf("plugin/dnsfilter: %s", err)
|
|
}
|
|
p.RUnlock()
|
|
|
|
if result.IsFiltered {
|
|
switch result.Reason {
|
|
case dnsfilter.FilteredSafeBrowsing:
|
|
// return cname safebrowsing.block.dns.adguard.com
|
|
val := p.settings.SafeBrowsingBlockHost
|
|
rcode, err := p.replaceHostWithValAndReply(ctx, w, r, host, val, question)
|
|
if err != nil {
|
|
return rcode, dnsfilter.Result{}, err
|
|
}
|
|
return rcode, result, err
|
|
case dnsfilter.FilteredParental:
|
|
// return cname family.block.dns.adguard.com
|
|
val := p.settings.ParentalBlockHost
|
|
rcode, err := p.replaceHostWithValAndReply(ctx, w, r, host, val, question)
|
|
if err != nil {
|
|
return rcode, dnsfilter.Result{}, err
|
|
}
|
|
return rcode, result, err
|
|
case dnsfilter.FilteredBlackList:
|
|
|
|
if result.Ip == nil {
|
|
// return NXDomain
|
|
rcode, err := p.writeNXdomain(ctx, w, r)
|
|
if err != nil {
|
|
return rcode, dnsfilter.Result{}, err
|
|
}
|
|
return rcode, result, err
|
|
} else {
|
|
// This is a hosts-syntax rule
|
|
rcode, err := p.replaceHostWithValAndReply(ctx, w, r, host, result.Ip.String(), question)
|
|
if err != nil {
|
|
return rcode, dnsfilter.Result{}, err
|
|
}
|
|
return rcode, result, err
|
|
}
|
|
case dnsfilter.FilteredInvalid:
|
|
// return NXdomain
|
|
rcode, err := p.writeNXdomain(ctx, w, r)
|
|
if err != nil {
|
|
return rcode, dnsfilter.Result{}, err
|
|
}
|
|
return rcode, result, err
|
|
default:
|
|
log.Printf("SHOULD NOT HAPPEN -- got unknown reason for filtering host \"%s\": %v, %+v", host, result.Reason, result)
|
|
}
|
|
} else {
|
|
switch result.Reason {
|
|
case dnsfilter.NotFilteredWhiteList:
|
|
rcode, err := plugin.NextOrFailure(p.Name(), p.Next, ctx, w, r)
|
|
return rcode, result, err
|
|
case dnsfilter.NotFilteredNotFound:
|
|
// do nothing, pass through to lower code
|
|
default:
|
|
log.Printf("SHOULD NOT HAPPEN -- got unknown reason for not filtering host \"%s\": %v, %+v", host, result.Reason, result)
|
|
}
|
|
}
|
|
}
|
|
rcode, err := plugin.NextOrFailure(p.Name(), p.Next, ctx, w, r)
|
|
return rcode, dnsfilter.Result{}, err
|
|
}
|
|
|
|
// ServeDNS handles the DNS request and refuses if it's in filterlists
|
|
func (p *plug) 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, result, err := p.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)
|
|
err = w.WriteMsg(answer)
|
|
if err != nil {
|
|
return dns.RcodeServerFailure, err
|
|
}
|
|
}
|
|
|
|
// 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
|
|
elapsed := time.Since(start)
|
|
elapsedTime.Observe(elapsed.Seconds())
|
|
if p.settings.QueryLogEnabled {
|
|
logRequest(r, rrw.Msg, result, time.Since(start), ip)
|
|
}
|
|
return rcode, err
|
|
}
|
|
|
|
// Name returns name of the plugin as seen in Corefile and plugin.cfg
|
|
func (p *plug) Name() string { return "dnsfilter" }
|
|
|
|
var onceHook sync.Once
|
|
var onceQueryLog sync.Once
|