ADDED: parallel queries to to multiple DNS servers

new setting ZabovParallelQueries: max number of parallel queries

01.conf.go

@@ -124,7 +124,28 @@ func init() {
 		} else {
 			conf.ZabovCache = true
 		}
-		conf.ZabovDNSArray = fileByLines(conf.ZabovUpDNS)
+		ZabovDNSArray := fileByLines(conf.ZabovUpDNS)
+
+		conf.ZabovDNSArray = []string{}
+
+		for _, value := range ZabovDNSArray {
+			tvalue := strings.TrimSpace(value)
+			if tvalue != "" && !strings.HasPrefix(tvalue, "#") {
+				conf.ZabovDNSArray = append(conf.ZabovDNSArray, tvalue)
+			}
+		}
+
+		if confRaw["parallelqueries"] != nil {
+			conf.ZabovParallelQueries = int(confRaw["parallelqueries"].(float64))
+		}
+		if conf.ZabovParallelQueries > len(conf.ZabovDNSArray) {
+			conf.ZabovParallelQueries = len(conf.ZabovDNSArray)
+		}
+		if conf.ZabovParallelQueries < 1 {
+			conf.ZabovParallelQueries = 1
+		}
+
+		fmt.Println("ZabovParallelQueries:", conf.ZabovParallelQueries)
 		ZabovConfigs[name] = &conf
 
 	}
@@ -282,7 +303,8 @@ func init() {
 			if localresponder["responder"] != nil {
 				ZabovLocalResponder = localresponder["responder"].(string)
 				if len(ZabovLocalResponder) > 0 {
-					local := ZabovConfig{ZabovDNSArray: []string{ZabovLocalResponder}, references: 1}
+					local := ZabovConfig{ZabovDNSArray: []string{ZabovLocalResponder},
+						references: 1, ZabovParallelQueries: 1}
 					ZabovConfigs[localresponderConfigName] = &local
 					fmt.Println("ZabovLocalResponder:", ZabovLocalResponder)
 				}

config.sample.json

@@ -36,7 +36,9 @@
             "singlefilters":"./urls-domains-updated.txt",
             "doublefilters":"./urls-hosts-normal.txt", 
             "blackholeip":"127.0.0.1",
-            "hostsfile":"./urls-local-normal.txt"
+            "hostsfile":"./urls-local-normal.txt",
+            "whitelist":"./urls-wl-normal.txt",
+            "parallelqueries":4
         },
         "children":{
             "upstream":"./dns-familyscreen.txt",

dns-upstream.txt

@@ -225,7 +225,6 @@
 212.89.128.28:53
 213.133.116.14:53
 213.166.247.100:53
-217.243.173.82:53
 217.5.182.118:53
 217.7.80.40:53
 217.7.81.136:53
@@ -362,7 +361,6 @@
 85.214.62.160:53
 85.93.91.101:53
 87.106.63.208:53
-87.118.126.225:53
 88.198.37.146:53
 88.99.66.18:53
 89.163.150.209:53

dns_client.go

@@ -11,6 +11,75 @@ import (
 	"github.com/miekg/dns"
 )
 
+func SingleResolve(query *dns.Msg, d string, lfqdn string, ch chan *dns.Msg) {
+	c := new(dns.Client)
+
+	c.ReadTimeout = 500 * time.Millisecond
+	c.WriteTimeout = 500 * time.Millisecond
+
+	in, _, err := c.Exchange(query, d)
+	if err != nil {
+		fmt.Printf("SingleResolve: Problem with DNS %s : %s\n", d, err.Error())
+		go incrementStats("DNS Problems "+d, 1)
+		ch <- nil
+	} else {
+		go incrementStats(d, 1)
+		Rcode := in.MsgHdr.Rcode
+		in.SetReply(query)
+		in.MsgHdr.Rcode = Rcode
+		in.Authoritative = true
+		in.Compress = true
+		go DomainCache(lfqdn, in)
+		if ZabovDebug {
+			log.Println("SingleResolve: OK:", d, lfqdn)
+		}
+		ch <- in
+	}
+}
+
+func ParallelResolve(query *dns.Msg, config string, lfqdn string) *dns.Msg {
+
+	var resCur *dns.Msg
+	var res *dns.Msg
+	ch := make(chan *dns.Msg)
+
+	dnss := oneTimeDNS(config, ZabovConfigs[config].ZabovParallelQueries)
+
+	for _, d := range dnss {
+		log.Println("ParallelResolve: running SingleResolve on:", d, lfqdn)
+		go SingleResolve(query, d, lfqdn, ch)
+	}
+
+	if ZabovDebug {
+		log.Println("ParallelResolve: wait for results...")
+	}
+	for range dnss {
+		resCur = <-ch
+		if resCur != nil {
+
+			if res == nil {
+				if ZabovDebug {
+					log.Println("ParallelResolve: got first result!")
+				}
+				res = resCur
+			} else if resCur.Rcode == dns.RcodeSuccess {
+				if ZabovDebug {
+					log.Println("ParallelResolve: got next result, RcodeSuccess, replacing previous...")
+				}
+				res = resCur
+			} else {
+				if ZabovDebug {
+					log.Println("ParallelResolve: got next result, discarding...")
+				}
+			}
+			if res.Rcode == dns.RcodeSuccess {
+				break
+			}
+		}
+	}
+	return res
+}
+
 //ForwardQuery forwards the query to the upstream server
 //first server to answer wins
 //accepts config name to select the UP DNS source list
@@ -39,15 +108,9 @@ func ForwardQuery(query *dns.Msg, config string, nocache bool) *dns.Msg {
 			}
 			cached.Compress = true
 			return cached
-
 		}
 	}
 
-	c := new(dns.Client)
-
-	c.ReadTimeout = 500 * time.Millisecond
-	c.WriteTimeout = 500 * time.Millisecond
-
 	for {
 		// round robin with retry
 
@@ -58,27 +121,10 @@ func ForwardQuery(query *dns.Msg, config string, nocache bool) *dns.Msg {
 			continue
 		}
 
-		d := oneTimeDNS(config)
-
-		in, _, err := c.Exchange(query, d)
-		if err != nil {
-			fmt.Printf("Problem with DNS %s : %s\n", d, err.Error())
-			go incrementStats("DNS Problems "+d, 1)
-			continue
-		} else {
-			go incrementStats(d, 1)
-			Rcode := in.MsgHdr.Rcode
-			in.SetReply(query)
-			in.MsgHdr.Rcode = Rcode
-			in.Authoritative = true
-			in.Compress = true
-			go DomainCache(lfqdn, in)
-			if ZabovDebug {
-				log.Println("ForwardQuery: OK!")
-			}
+		in := ParallelResolve(query, config, lfqdn)
 
+		if in != nil {
 			return in
-
 		}
 
 	}
@@ -98,9 +144,12 @@ func init() {
 
 }
 
-func oneTimeDNS(config string) (dns string) {
+func oneTimeDNS(config string, count int) (dns []string) {
 
-	rand.Seed(time.Now().Unix())
+	if count == 0 {
+		count = 1
+	}
+	rand.Seed(time.Now().UnixNano())
 
 	upl := ZabovConfigs[config].ZabovDNSArray
 
@@ -108,16 +157,27 @@ func oneTimeDNS(config string) (dns string) {
 
 		if len(ZabovLocalResponder) > 0 {
 			fmt.Println("No DNS defined, fallback to local responder:", ZabovLocalResponder)
-			return ZabovLocalResponder
+			return []string{ZabovLocalResponder}
 		}
 		fmt.Println("No DNS defined, using default 127.0.0.53:53. Hope it works!")
-		return "127.0.0.53:53"
+		return []string{"127.0.0.53:53"}
 	}
 
 	n := rand.Intn(128*len(upl)) % len(upl)
 
-	dns = upl[n]
+	res := []string{}
+	for i := 0; i < count; i++ {
+		res = append(res, upl[(n+i)%len(upl)])
+	}
 
-	return
+	check := make(map[string]int)
+	for _, val := range res {
+		check[val] = 1
+	}
 
+	res = []string{}
+	for d, _ := range check {
+		res = append(res, d)
+	}
+	return res
 }

main.go

@@ -35,15 +35,16 @@ type handler struct{}
 
 // ZabovConfig contains all Zabov configs
 type ZabovConfig struct {
-	ZabovSingleBL  string   // json:singlefilters -> ZabovSingleBL list of urls returning a file with just names of domains
-	ZabovDoubleBL  string   // json:doublefilters -> ZabovDoubleBL list of urls returning a file with  IP<space>domain
-	ZabovAddBL     net.IP   // json:blackholeip  -> ZabovAddBL is the IP we want to send all the clients to. Usually is 127.0.0.1
-	ZabovHostsFile string   // json:hostsfile -> ZabovHostsFile is the file we use to keep our hosts
-	ZabovWhiteList string   // json:hostsfile -> ZabovWhiteList is the file we use to keep white listed hosts
-	ZabovUpDNS     string   // json:upstream -> ZabovUpDNS keeps the name of upstream DNSs
-	ZabovDNSArray  []string // contains all the DNS we mention, parsed from ZabovUpDNS file
-	ZabovCache     bool     // allows to disable cache
-	references     int      // contains references to this config; if zero, config shall be removed
+	ZabovSingleBL        string   // json:singlefilters -> ZabovSingleBL list of urls returning a file with just names of domains
+	ZabovDoubleBL        string   // json:doublefilters -> ZabovDoubleBL list of urls returning a file with  IP<space>domain
+	ZabovAddBL           net.IP   // json:blackholeip  -> ZabovAddBL is the IP we want to send all the clients to. Usually is 127.0.0.1
+	ZabovHostsFile       string   // json:hostsfile -> ZabovHostsFile is the file we use to keep our hosts
+	ZabovWhiteList       string   // json:hostsfile -> ZabovWhiteList is the file we use to keep white listed hosts
+	ZabovUpDNS           string   // json:upstream -> ZabovUpDNS keeps the name of upstream DNSs
+	ZabovDNSArray        []string // contains all the DNS we mention, parsed from ZabovUpDNS file
+	ZabovCache           bool     // allows to disable cache
+	ZabovParallelQueries int      // contains max number of parallel queries to multiple DNS servers
+	references           int      // contains references to this config; if zero, config shall be removed
 }
 
 // ZabovConfigs contains all Zabov configs