diff --git a/Makefile b/Makefile index a41dbbd..129c8e3 100644 --- a/Makefile +++ b/Makefile @@ -8,20 +8,22 @@ SHELL := /bin/bash .PHONY: default default: repo -GOPATH=$(shell pwd)/go_$(VERSION) +mkfile_path := $(abspath $(lastword $(MAKEFILE_LIST))) +mkfile_dir := $(patsubst %/,%,$(dir $(mkfile_path))) +GOPATH := $(mkfile_dir)/go_$(VERSION) clean: rm -fv *.deb build: check-vars clean - mkdir -p $(GOPATH) - GOPATH=$(GOPATH) go get -v -d github.com/AdguardTeam/AdguardDNS + mkdir -p $(GOPATH)/src/bit.adguard.com/dns + if [ ! -h $(GOPATH)/src/bit.adguard.com/dns/adguard-internal-dns ]; then rm -rf $(GOPATH)/src/bit.adguard.com/dns/adguard-internal-dns && ln -fs $(mkfile_dir) $(GOPATH)/src/bit.adguard.com/dns/adguard-internal-dns; fi GOPATH=$(GOPATH) go get -v -d github.com/coredns/coredns cp plugin.cfg $(GOPATH)/src/github.com/coredns/coredns cd $(GOPATH)/src/github.com/coredns/coredns; GOPATH=$(GOPATH) go generate cd $(GOPATH)/src/github.com/coredns/coredns; GOPATH=$(GOPATH) go get -v -d -t . cd $(GOPATH)/src/github.com/coredns/coredns; GOPATH=$(GOPATH) PATH=$(GOPATH)/bin:$(PATH) make - cd $(GOPATH)/src/github.com/coredns/coredns; GOPATH=$(GOPATH) go build -x -v -ldflags="-X github.com/coredns/coredns/coremain.GitCommit=$(VERSION)" -o $(GOPATH)/bin/coredns + cd $(GOPATH)/src/github.com/coredns/coredns; GOPATH=$(GOPATH) go build -x -v -ldflags="-X github.com/coredns/coredns/coremain.GitCommit=$(VERSION)" -asmflags="-trimpath=$(GOPATH)" -gcflags="-trimpath=$(GOPATH)" -o $(GOPATH)/bin/coredns package: build fpm --prefix /usr/local/bin \ diff --git a/coredns_plugin/coredns_plugin.go b/coredns_plugin/coredns_plugin.go new file mode 100644 index 0000000..7ed8031 --- /dev/null +++ b/coredns_plugin/coredns_plugin.go @@ -0,0 +1,539 @@ +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/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 + 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(), + } + + 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.EnableSafeBrowsing() + 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.EnableSafeSearch() + 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") + err = p.d.EnableParental(sensitivity) + if err != nil { + return nil, c.ArgErr() + } + 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 + } + } + + 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 { + 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) +} + +// lookup host, but return answer as if it was a result of origname lookup +func lookupReplaced(host string, origname string) ([]dns.RR, error) { + var records []dns.RR + var res *net.Resolver // nil resolver is default resolver + addrs, err := res.LookupIPAddr(context.TODO(), host) + if err != nil { + return nil, err + } + for _, addr := range addrs { + ip := addr.IP + var rr dns.RR + var err error + if ip.To4() != nil { + // ipv4 -> A + rr, err = dns.NewRR(fmt.Sprintf("%s A %s", origname, ip.String())) + if err != nil { + return nil, err // fail entire request + // TODO: return only successful answers? + } + } else { + // ipv6 -> AAAA + rr, err = dns.NewRR(fmt.Sprintf("%s AAAA %s", origname, ip.String())) + if err != nil { + return nil, err // fail entire request + // TODO: return only successful answers? + } + } + records = append(records, rr) + } + return records, nil +} + +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 + var err error + records, err = lookupReplaced(dns.Fqdn(val), question.Name) + if err != nil { + log.Printf("Got error %s\n", err) + return dns.RcodeServerFailure, fmt.Errorf("plugin/dnsfilter: %s", err) + } + } + 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 + } + + // 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} + + // 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()) + return rcode, err +} + +// Name returns name of the plugin as seen in Corefile and plugin.cfg +func (p *plug) Name() string { return "dnsfilter" } diff --git a/coredns_plugin/coredns_plugin_test.go b/coredns_plugin/coredns_plugin_test.go new file mode 100644 index 0000000..1733fd6 --- /dev/null +++ b/coredns_plugin/coredns_plugin_test.go @@ -0,0 +1,131 @@ +package dnsfilter + +import ( + "context" + "fmt" + "io/ioutil" + "net" + "os" + "testing" + + "github.com/coredns/coredns/plugin" + "github.com/coredns/coredns/plugin/pkg/dnstest" + "github.com/coredns/coredns/plugin/test" + "github.com/mholt/caddy" + "github.com/miekg/dns" +) + +func TestSetup(t *testing.T) { + for i, testcase := range []struct { + config string + failing bool + }{ + {`dnsfilter`, false}, + {`dnsfilter { + filter 0 /dev/nonexistent/abcdef + }`, true}, + {`dnsfilter { + filter 0 ../tests/dns.txt + }`, false}, + {`dnsfilter { + safebrowsing + filter 0 ../tests/dns.txt + }`, false}, + {`dnsfilter { + parental + filter 0 ../tests/dns.txt + }`, true}, + } { + c := caddy.NewTestController("dns", testcase.config) + err := setup(c) + if err != nil { + if !testcase.failing { + t.Fatalf("Test #%d expected no errors, but got: %v", i, err) + } + continue + } + if testcase.failing { + t.Fatalf("Test #%d expected to fail but it didn't", i) + } + } +} + +func TestEtcHostsFilter(t *testing.T) { + text := []byte("127.0.0.1 doubleclick.net\n" + "127.0.0.1 example.org example.net www.example.org www.example.net") + tmpfile, err := ioutil.TempFile("", "") + if err != nil { + t.Fatal(err) + } + if _, err = tmpfile.Write(text); err != nil { + t.Fatal(err) + } + if err = tmpfile.Close(); err != nil { + t.Fatal(err) + } + + defer os.Remove(tmpfile.Name()) + + configText := fmt.Sprintf("dnsfilter {\nfilter 0 %s\n}", tmpfile.Name()) + c := caddy.NewTestController("dns", configText) + p, err := setupPlugin(c) + if err != nil { + t.Fatal(err) + } + + p.Next = zeroTTLBackend() + + ctx := context.TODO() + + for _, testcase := range []struct { + host string + filtered bool + }{ + {"www.doubleclick.net", false}, + {"doubleclick.net", true}, + {"www2.example.org", false}, + {"www2.example.net", false}, + {"test.www.example.org", false}, + {"test.www.example.net", false}, + {"example.org", true}, + {"example.net", true}, + {"www.example.org", true}, + {"www.example.net", true}, + } { + req := new(dns.Msg) + req.SetQuestion(testcase.host+".", dns.TypeA) + + resp := test.ResponseWriter{} + rrw := dnstest.NewRecorder(&resp) + rcode, err := p.ServeDNS(ctx, rrw, req) + if err != nil { + t.Fatalf("ServeDNS returned error: %s", err) + } + if rcode != rrw.Rcode { + t.Fatalf("ServeDNS return value for host %s has rcode %d that does not match captured rcode %d", testcase.host, rcode, rrw.Rcode) + } + A, ok := rrw.Msg.Answer[0].(*dns.A) + if !ok { + t.Fatalf("Host %s expected to have result A", testcase.host) + } + ip := net.IPv4(127, 0, 0, 1) + filtered := ip.Equal(A.A) + if testcase.filtered && testcase.filtered != filtered { + t.Fatalf("Host %s expected to be filtered, instead it is not filtered", testcase.host) + } + if !testcase.filtered && testcase.filtered != filtered { + t.Fatalf("Host %s expected to be not filtered, instead it is filtered", testcase.host) + } + } +} + +func zeroTTLBackend() plugin.Handler { + return plugin.HandlerFunc(func(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { + m := new(dns.Msg) + m.SetReply(r) + m.Response, m.RecursionAvailable = true, true + + m.Answer = []dns.RR{test.A("example.org. 0 IN A 127.0.0.53")} + w.WriteMsg(m) + return dns.RcodeSuccess, nil + }) +} diff --git a/coredns_plugin/coredns_stats.go b/coredns_plugin/coredns_stats.go new file mode 100644 index 0000000..6c3de19 --- /dev/null +++ b/coredns_plugin/coredns_stats.go @@ -0,0 +1,189 @@ +package dnsfilter + +import ( + "sync" + "time" + + "github.com/coredns/coredns/plugin" + "github.com/prometheus/client_golang/prometheus" +) + +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.") + elapsedTime = newDNSHistogram("request_duration", "Histogram of the time (in seconds) each request took.") +) + +// entries for single time period (for example all per-second entries) +type statsEntries map[string][statsHistoryElements]float64 + +// how far back to keep the stats +const statsHistoryElements = 60 + 1 // +1 for calculating delta + +// each periodic stat is a map of arrays +type periodicStats struct { + Entries statsEntries + period time.Duration // how long one entry lasts + LastRotate time.Time // last time this data was rotated + + sync.RWMutex +} + +type stats struct { + PerSecond periodicStats + PerMinute periodicStats + PerHour periodicStats + PerDay periodicStats +} + +// per-second/per-minute/per-hour/per-day stats +var statistics stats + +func initPeriodicStats(periodic *periodicStats, period time.Duration) { + periodic.Entries = statsEntries{} + periodic.LastRotate = time.Now() + periodic.period = period +} + +func init() { + purgeStats() +} + +func purgeStats() { + initPeriodicStats(&statistics.PerSecond, time.Second) + initPeriodicStats(&statistics.PerMinute, time.Minute) + initPeriodicStats(&statistics.PerHour, time.Hour) + initPeriodicStats(&statistics.PerDay, time.Hour*24) +} + +func (p *periodicStats) Inc(name string, when time.Time) { + // calculate how many periods ago this happened + elapsed := int64(time.Since(when) / p.period) + // trace("%s: %v as %v -> [%v]", name, time.Since(when), p.period, elapsed) + if elapsed >= statsHistoryElements { + return // outside of our timeframe + } + p.Lock() + currentValues := p.Entries[name] + currentValues[elapsed]++ + p.Entries[name] = currentValues + p.Unlock() +} + +func (p *periodicStats) Observe(name string, when time.Time, value float64) { + // calculate how many periods ago this happened + elapsed := int64(time.Since(when) / p.period) + // trace("%s: %v as %v -> [%v]", name, time.Since(when), p.period, elapsed) + if elapsed >= statsHistoryElements { + return // outside of our timeframe + } + p.Lock() + { + countname := name + "_count" + currentValues := p.Entries[countname] + value := currentValues[elapsed] + // trace("Will change p.Entries[%s][%d] from %v to %v", countname, elapsed, value, value+1) + value++ + currentValues[elapsed] = value + p.Entries[countname] = currentValues + } + { + totalname := name + "_sum" + currentValues := p.Entries[totalname] + currentValues[elapsed] += value + p.Entries[totalname] = currentValues + } + p.Unlock() +} + +// counter that wraps around prometheus Counter but also adds to periodic stats +type counter struct { + name string // used as key in periodic stats + value int64 + prom prometheus.Counter +} + +func newDNSCounter(name string, help string) *counter { + // trace("called") + c := &counter{} + c.prom = prometheus.NewCounter(prometheus.CounterOpts{ + Namespace: plugin.Namespace, + Subsystem: "dnsfilter", + Name: name, + Help: help, + }) + c.name = name + + return c +} + +func (c *counter) IncWithTime(when time.Time) { + statistics.PerSecond.Inc(c.name, when) + statistics.PerMinute.Inc(c.name, when) + statistics.PerHour.Inc(c.name, when) + statistics.PerDay.Inc(c.name, when) + c.value++ + c.prom.Inc() +} + +func (c *counter) Inc() { + c.IncWithTime(time.Now()) +} + +func (c *counter) Describe(ch chan<- *prometheus.Desc) { + c.prom.Describe(ch) +} + +func (c *counter) Collect(ch chan<- prometheus.Metric) { + c.prom.Collect(ch) +} + +type histogram struct { + name string // used as key in periodic stats + count int64 + total float64 + prom prometheus.Histogram +} + +func newDNSHistogram(name string, help string) *histogram { + // trace("called") + h := &histogram{} + h.prom = prometheus.NewHistogram(prometheus.HistogramOpts{ + Namespace: plugin.Namespace, + Subsystem: "dnsfilter", + Name: name, + Help: help, + }) + h.name = name + + return h +} + +func (h *histogram) ObserveWithTime(value float64, when time.Time) { + statistics.PerSecond.Observe(h.name, when, value) + statistics.PerMinute.Observe(h.name, when, value) + statistics.PerHour.Observe(h.name, when, value) + statistics.PerDay.Observe(h.name, when, value) + h.count++ + h.total += value + h.prom.Observe(value) +} + +func (h *histogram) Observe(value float64) { + h.ObserveWithTime(value, time.Now()) +} + +func (h *histogram) Describe(ch chan<- *prometheus.Desc) { + h.prom.Describe(ch) +} + +func (h *histogram) Collect(ch chan<- prometheus.Metric) { + h.prom.Collect(ch) +} diff --git a/coredns_plugin/ratelimit/ratelimit.go b/coredns_plugin/ratelimit/ratelimit.go new file mode 100644 index 0000000..8d3eeec --- /dev/null +++ b/coredns_plugin/ratelimit/ratelimit.go @@ -0,0 +1,182 @@ +package ratelimit + +import ( + "errors" + "log" + "sort" + "strconv" + "time" + + // ratelimiting and per-ip buckets + "github.com/beefsack/go-rate" + "github.com/patrickmn/go-cache" + + // coredns plugin + "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/request" + "github.com/mholt/caddy" + "github.com/miekg/dns" + "github.com/prometheus/client_golang/prometheus" + "golang.org/x/net/context" +) + +const defaultRatelimit = 30 +const defaultResponseSize = 1000 + +var ( + tokenBuckets = cache.New(time.Hour, time.Hour) +) + +// ServeDNS handles the DNS request and refuses if it's an beyind specified ratelimit +func (p *plug) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { + state := request.Request{W: w, Req: r} + ip := state.IP() + allow, err := p.allowRequest(ip) + if err != nil { + return 0, err + } + if !allow { + ratelimited.Inc() + return 0, nil + } + + // Record response to get status code and size of the reply. + rw := dnstest.NewRecorder(w) + status, err := plugin.NextOrFailure(p.Name(), p.Next, ctx, rw, r) + + size := rw.Len + + if size > defaultResponseSize && state.Proto() == "udp" { + // For large UDP responses we call allowRequest more times + // The exact number of times depends on the response size + for i := 0; i < size/defaultResponseSize; i++ { + p.allowRequest(ip) + } + } + + return status, err +} + +func (p *plug) allowRequest(ip string) (bool, error) { + if len(p.whitelist) > 0 { + i := sort.SearchStrings(p.whitelist, ip) + + if i < len(p.whitelist) && p.whitelist[i] == ip { + return true, nil + } + } + + if _, found := tokenBuckets.Get(ip); !found { + tokenBuckets.Set(ip, rate.New(p.ratelimit, time.Second), time.Hour) + } + + value, found := tokenBuckets.Get(ip) + if !found { + // should not happen since we've just inserted it + text := "SHOULD NOT HAPPEN: just-inserted ratelimiter disappeared" + log.Println(text) + err := errors.New(text) + return true, err + } + + rl, ok := value.(*rate.RateLimiter) + if !ok { + text := "SHOULD NOT HAPPEN: non-bool entry found in safebrowsing lookup cache" + log.Println(text) + err := errors.New(text) + return true, err + } + + allow, _ := rl.Try() + return allow, nil +} + +// +// helper functions +// +func init() { + caddy.RegisterPlugin("ratelimit", caddy.Plugin{ + ServerType: "dns", + Action: setup, + }) +} + +type plug struct { + Next plugin.Handler + + // configuration for creating above + ratelimit int // in requests per second per IP + whitelist []string // a list of whitelisted IP addresses +} + +func setupPlugin(c *caddy.Controller) (*plug, error) { + p := &plug{ratelimit: defaultRatelimit} + + for c.Next() { + args := c.RemainingArgs() + if len(args) > 0 { + ratelimit, err := strconv.Atoi(args[0]) + if err != nil { + return nil, c.ArgErr() + } + p.ratelimit = ratelimit + } + for c.NextBlock() { + switch c.Val() { + case "whitelist": + p.whitelist = c.RemainingArgs() + + if len(p.whitelist) > 0 { + sort.Strings(p.whitelist) + } + } + } + } + + 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(ratelimited) + } + return nil + }) + + return nil +} + +func newDNSCounter(name string, help string) prometheus.Counter { + return prometheus.NewCounter(prometheus.CounterOpts{ + Namespace: plugin.Namespace, + Subsystem: "ratelimit", + Name: name, + Help: help, + }) +} + +var ( + ratelimited = newDNSCounter("dropped_total", "Count of requests that have been dropped because of rate limit") +) + +// Name returns name of the plugin as seen in Corefile and plugin.cfg +func (p *plug) Name() string { return "ratelimit" } diff --git a/coredns_plugin/ratelimit/ratelimit_test.go b/coredns_plugin/ratelimit/ratelimit_test.go new file mode 100644 index 0000000..b426f2e --- /dev/null +++ b/coredns_plugin/ratelimit/ratelimit_test.go @@ -0,0 +1,80 @@ +package ratelimit + +import ( + "testing" + + "github.com/mholt/caddy" +) + +func TestSetup(t *testing.T) { + for i, testcase := range []struct { + config string + failing bool + }{ + {`ratelimit`, false}, + {`ratelimit 100`, false}, + {`ratelimit { + whitelist 127.0.0.1 + }`, false}, + {`ratelimit 50 { + whitelist 127.0.0.1 176.103.130.130 + }`, false}, + {`ratelimit test`, true}, + } { + c := caddy.NewTestController("dns", testcase.config) + err := setup(c) + if err != nil { + if !testcase.failing { + t.Fatalf("Test #%d expected no errors, but got: %v", i, err) + } + continue + } + if testcase.failing { + t.Fatalf("Test #%d expected to fail but it didn't", i) + } + } +} + +func TestRatelimiting(t *testing.T) { + // rate limit is 1 per sec + c := caddy.NewTestController("dns", `ratelimit 1`) + p, err := setupPlugin(c) + + if err != nil { + t.Fatal("Failed to initialize the plugin") + } + + allowed, err := p.allowRequest("127.0.0.1") + + if err != nil || !allowed { + t.Fatal("First request must have been allowed") + } + + allowed, err = p.allowRequest("127.0.0.1") + + if err != nil || allowed { + t.Fatal("Second request must have been ratelimited") + } +} + +func TestWhitelist(t *testing.T) { + // rate limit is 1 per sec + c := caddy.NewTestController("dns", `ratelimit 1 { whitelist 127.0.0.2 127.0.0.1 127.0.0.125 }`) + p, err := setupPlugin(c) + + if err != nil { + t.Fatal("Failed to initialize the plugin") + } + + allowed, err := p.allowRequest("127.0.0.1") + + if err != nil || !allowed { + t.Fatal("First request must have been allowed") + } + + allowed, err = p.allowRequest("127.0.0.1") + + if err != nil || !allowed { + t.Fatal("Second request must have been allowed due to whitelist") + } +} diff --git a/coredns_plugin/refuseany/refuseany.go b/coredns_plugin/refuseany/refuseany.go new file mode 100644 index 0000000..92d5d50 --- /dev/null +++ b/coredns_plugin/refuseany/refuseany.go @@ -0,0 +1,91 @@ +package refuseany + +import ( + "fmt" + "log" + + "github.com/coredns/coredns/core/dnsserver" + "github.com/coredns/coredns/plugin" + "github.com/coredns/coredns/plugin/metrics" + "github.com/coredns/coredns/request" + "github.com/mholt/caddy" + "github.com/miekg/dns" + "github.com/prometheus/client_golang/prometheus" + "golang.org/x/net/context" +) + +type plug struct { + Next plugin.Handler +} + +// ServeDNS handles the DNS request and refuses if it's an ANY request +func (p *plug) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) { + if len(r.Question) != 1 { + // google DNS, bind and others do the same + return dns.RcodeFormatError, fmt.Errorf("Got DNS request with != 1 questions") + } + + q := r.Question[0] + if q.Qtype == dns.TypeANY { + state := request.Request{W: w, Req: r, Context: ctx} + rcode := dns.RcodeNotImplemented + + m := new(dns.Msg) + m.SetRcode(r, rcode) + state.SizeAndDo(m) + err := state.W.WriteMsg(m) + if err != nil { + log.Printf("Got error %s\n", err) + return dns.RcodeServerFailure, err + } + return rcode, nil + } + + return plugin.NextOrFailure(p.Name(), p.Next, ctx, w, r) +} + +func init() { + caddy.RegisterPlugin("refuseany", caddy.Plugin{ + ServerType: "dns", + Action: setup, + }) +} + +func setup(c *caddy.Controller) error { + p := &plug{} + 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(ratelimited) + } + return nil + }) + + return nil +} + +func newDNSCounter(name string, help string) prometheus.Counter { + return prometheus.NewCounter(prometheus.CounterOpts{ + Namespace: plugin.Namespace, + Subsystem: "refuseany", + Name: name, + Help: help, + }) +} + +var ( + ratelimited = newDNSCounter("refusedany_total", "Count of ANY requests that have been dropped") +) + +// Name returns name of the plugin as seen in Corefile and plugin.cfg +func (p *plug) Name() string { return "refuseany" } diff --git a/plugin.cfg b/plugin.cfg index b5a1784..259f5c4 100644 --- a/plugin.cfg +++ b/plugin.cfg @@ -26,9 +26,9 @@ pprof:pprof prometheus:metrics errors:errors log:log -ratelimit:github.com/AdguardTeam/AdguardDNS/coredns_plugin/ratelimit -refuseany:github.com/AdguardTeam/AdguardDNS/coredns_plugin/refuseany -dnsfilter:github.com/AdguardTeam/AdguardDNS/coredns_plugin +ratelimit:bit.adguard.com/dns/adguard-internal-dns/coredns_plugin/ratelimit +refuseany:bit.adguard.com/dns/adguard-internal-dns/coredns_plugin/refuseany +dnsfilter:bit.adguard.com/dns/adguard-internal-dns/coredns_plugin cache:cache template:template file:file