Merge pull request #14 in DNS/adguard-dns from dnsfilter_recursion to master

* commit 'd49e3769a105f4dee639b9dec1112b123b7a23aa':
  dnsfilter -- do not check lookup hosts against themselves to avoid recursion
  Add support for serving /etc/hosts
  Makefile -- Fix cross-compilation

Makefile

@@ -24,13 +24,13 @@ AdguardDNS: $(STATIC) *.go
 coredns: coredns_plugin/*.go dnsfilter/*.go
 	echo mkfile_dir = $(mkfile_dir)
 	go get -v -d github.com/coredns/coredns
+	cd $(GOPATH)/src/github.com/prometheus/client_golang && git checkout -q v0.8.0
 	cd $(GOPATH)/src/github.com/coredns/coredns && perl -p -i.bak -e 's/^(trace|route53|federation|kubernetes|etcd):.*//' plugin.cfg
 	cd $(GOPATH)/src/github.com/coredns/coredns && grep -q '^dnsfilter:' plugin.cfg || perl -p -i.bak -e 's|^log:log|log:log\ndnsfilter:github.com/AdguardTeam/AdguardDNS/coredns_plugin|' plugin.cfg
 	grep '^dnsfilter:' $(GOPATH)/src/github.com/coredns/coredns/plugin.cfg ## used to check that plugin.cfg was successfully edited by sed
 	cd $(GOPATH)/src/github.com/coredns/coredns && GOOS=$(NATIVE_GOOS) GOARCH=$(NATIVE_GOARCH) go generate
 	cd $(GOPATH)/src/github.com/coredns/coredns && go get -v -d .
-	cd $(GOPATH)/src/github.com/coredns/coredns && make
+	cd $(GOPATH)/src/github.com/coredns/coredns && go build -o $(mkfile_dir)/coredns
-	cd $(GOPATH)/src/github.com/coredns/coredns && mv coredns $(mkfile_dir)/coredns
 
 clean:
 	rm -vf coredns AdguardDNS

config.go

@@ -165,6 +165,9 @@ const coreDNSConfigTemplate = `. {
         {{if .QueryLogEnabled}}querylog{{end}}
     }{{end}}
     {{.Pprof}}
+	hosts {
+		fallthrough
+	}
     {{if .UpstreamDNS}}forward . {{range .UpstreamDNS}}{{.}} {{end}}{{end}}
     {{.Cache}}
     {{.Prometheus}}

dnsfilter/dnsfilter.go

@@ -28,7 +28,8 @@ const defaultHTTPMaxIdleConnections = 100
 
 const defaultSafebrowsingServer = "sb.adtidy.org"
 const defaultSafebrowsingURL = "http://%s/safebrowsing-lookup-hash.html?prefixes=%s"
-const defaultParentalURL = "http://pctrl.adguard.com/check-parental-control-hash?prefixes=%s&sensitivity=%d"
+const defaultParentalServer = "pctrl.adguard.com"
+const defaultParentalURL = "http://%s/check-parental-control-hash?prefixes=%s&sensitivity=%d"
 
 var ErrInvalidSyntax = errors.New("dnsfilter: invalid rule syntax")
 var ErrInvalidParental = errors.New("dnsfilter: invalid parental sensitivity, must be either 3, 10, 13 or 17")
@@ -43,6 +44,7 @@ type Config struct {
 	safeBrowsingEnabled bool
 	safeBrowsingServer  string
 	parentalEnabled     bool
+	parentalServer      string
 	parentalSensitivity int // must be either 3, 10, 13 or 17
 }
 
@@ -140,6 +142,7 @@ func (d *Dnsfilter) CheckHost(host string) (Result, error) {
 	if host == "" {
 		return Result{Reason: FilteredInvalid}, nil
 	}
+	host = strings.ToLower(host)
 
 	// try filter lists first
 	result, err := d.matchHost(host)
@@ -487,6 +490,10 @@ func hostnameToHashParam(host string, addslash bool) (string, map[string]bool) {
 }
 
 func (d *Dnsfilter) checkSafeBrowsing(host string) (Result, error) {
+	// prevent recursion -- checking the host of safebrowsing server makes no sense
+	if host == d.config.safeBrowsingServer {
+		return Result{}, nil
+	}
 	format := func(hashparam string) string {
 		url := fmt.Sprintf(defaultSafebrowsingURL, d.config.safeBrowsingServer, hashparam)
 		return url
@@ -521,8 +528,12 @@ func (d *Dnsfilter) checkSafeBrowsing(host string) (Result, error) {
 }
 
 func (d *Dnsfilter) checkParental(host string) (Result, error) {
+	// prevent recursion -- checking the host of parental safety server makes no sense
+	if host == d.config.parentalServer {
+		return Result{}, nil
+	}
 	format := func(hashparam string) string {
-		url := fmt.Sprintf(defaultParentalURL, hashparam, d.config.parentalSensitivity)
+		url := fmt.Sprintf(defaultParentalURL, d.config.parentalServer, hashparam, d.config.parentalSensitivity)
 		return url
 	}
 	handleBody := func(body []byte, hashes map[string]bool) (Result, error) {
@@ -723,6 +734,8 @@ func New() *Dnsfilter {
 		Timeout:   defaultHTTPTimeout,
 	}
 	d.config.safeBrowsingServer = defaultSafebrowsingServer
+	d.config.parentalServer = defaultParentalServer
+
 	return d
 }