- BUG FIX: preserving DNS RCode in Zabov responses (SetReply(query) resets it to RcodeSuccess)

Some DNS client (such as MS Windows) misbehave in case of always positive responses

01.conf.go

@@ -13,10 +13,13 @@ import (
 	"github.com/miekg/dns"
 )
 
+var localresponderConfigName string
+
 type stringarray []string
 type urlsMap map[string]stringarray
 
 func init() {
+	localresponderConfigName = "__localresponder__"
 	var MyConfRaw interface{}
 
 	file, err := ioutil.ReadFile("config.json")
@@ -107,9 +110,14 @@ func init() {
 		conf.ZabovUpDNS = confRaw["upstream"].(string)
 		conf.ZabovSingleBL = confRaw["singlefilters"].(string)
 		conf.ZabovDoubleBL = confRaw["doublefilters"].(string)
-		conf.ZabovAddBL = confRaw["blackholeip"].(string)
+		conf.ZabovAddBL = net.ParseIP(confRaw["blackholeip"].(string))
 		conf.ZabovHostsFile = confRaw["hostsfile"].(string)
 
+		if confRaw["cache"] != nil {
+			conf.ZabovCache = confRaw["cache"].(bool)
+		} else {
+			conf.ZabovCache = true
+		}
 		conf.ZabovDNSArray = fileByLines(conf.ZabovUpDNS)
 		ZabovConfigs[name] = &conf
 
@@ -216,8 +224,16 @@ func init() {
 				}
 				groupStruct.ips = append(groupStruct.ips, ip)
 			}
+			if groupMap["cfg"] != nil {
 				groupStruct.cfg = groupMap["cfg"].(string)
+			}
+			if groupMap["timetable"] != nil {
 				groupStruct.timetable = groupMap["timetable"].(string)
+			}
+			if len(groupStruct.cfg) == 0 && len(groupStruct.timetable) == 0 {
+				log.Println("ip group error: specify cfg or timetable")
+				os.Exit(1)
+			}
 			if len(groupStruct.cfg) > 0 {
 				refConfig, ok := ZabovConfigs[groupStruct.cfg]
 				if !ok {
@@ -226,14 +242,17 @@ func init() {
 				} else {
 					refConfig.references++
 				}
-			}
 				fmt.Println("cfg:", groupStruct.cfg)
+			}
+			if len(groupStruct.timetable) > 0 {
 				fmt.Println("timetable:", groupStruct.timetable)
 				_, ok := ZabovTimetables[groupStruct.timetable]
 				if !ok {
 					log.Println("inexistent timetable:", groupStruct.timetable)
 					os.Exit(1)
 				}
+			}
+
 			ZabovIPGroups = append(ZabovIPGroups, groupStruct)
 		}
 	}
@@ -248,7 +267,7 @@ func init() {
 	}
 
 	//************************
-	// Local responser section
+	// Local responder section
 	//************************
 	if MyConf["localresponder"] != nil {
 		localresponder := MyConf["localresponder"].(map[string]interface{})
@@ -258,7 +277,7 @@ func init() {
 				ZabovLocalResponder = localresponder["responder"].(string)
 				if len(ZabovLocalResponder) > 0 {
 					local := ZabovConfig{ZabovDNSArray: []string{ZabovLocalResponder}, references: 1}
-					ZabovConfigs["__localresponder__"] = &local
+					ZabovConfigs[localresponderConfigName] = &local
 					fmt.Println("ZabovLocalResponder:", ZabovLocalResponder)
 				}
 			}

README.md

@@ -62,7 +62,8 @@ Minimal config file should look like:
             "singlefilters":"./urls-domains.txt",
             "doublefilters":"./urls-hosts.txt", 
             "blackholeip":"127.0.0.1",
-            "hostsfile":"./urls-local.txt"
+            "hostsfile":"./urls-local.txt",
+            "cache":true
         },
     }
 }
@@ -84,7 +85,7 @@ configs:
 - doublefilters: name of the file, for blacklists following the "doublefilter" schema.(one URL per line)
 - blackholeip: IP address to return when the IP is banned. This is because you may want to avoid MX issues, mail loops on localhost, or you have a web server running on localhost
 - hostsfile: path where you keep your local blacklistfile : this is in the format "singlefilter", meaning one domain per line, unlike hosts file.
-
+- cache: if set to false disable the cache for this configuration. Boolean, defaults true
 
 Advanced configuration includes support for multiple configurations based on IP Source and timetables:
 <pre>
@@ -104,6 +105,7 @@ Advanced configuration includes support for multiple configurations based on IP
     },
     "ipaliases":{
         "pc8":"192.168.178.29",
+        "lg-tv":"192.168.178.10",
         "localhost":"127.0.0.1"
     },
     "ipgroups":[
@@ -111,6 +113,11 @@ Advanced configuration includes support for multiple configurations based on IP
             "ips":["localhost", "::1", "192.168.178.30", "192.168.178.31", "pc8"],
             "cfg":"",
             "timetable":"tt_children"
+        },
+        {
+            "ips":["lg-tv"],
+            "cfg":"tv",
+            "timetable":""
         }
     ],
     "timetables":{
@@ -146,6 +153,14 @@ Advanced configuration includes support for multiple configurations based on IP
             "doublefilters":"./urls-hosts-restricted.txt", 
             "blackholeip":"127.0.0.1",
             "hostsfile":"./urls-local.txt"
+        },
+        "tv":{
+            "upstream":"./dns-upstream.txt",
+            "singlefilters":"",
+            "doublefilters":"", 
+            "blackholeip":"127.0.0.1",
+            "hostsfile":"",
+            "cache":false
         }
     }
 }

dns_client.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"log"
 	"time"
 
 	"math/rand"
@@ -14,7 +15,9 @@ import (
 //first server to answer wins
 //accepts config name to select the UP DNS source list
 func ForwardQuery(query *dns.Msg, config string, nocache bool) *dns.Msg {
-
+	if ZabovDebug {
+		log.Println("ForwardQuery: nocache", nocache)
+	}
 	go incrementStats("ForwardQueries", 1)
 
 	r := new(dns.Msg)
@@ -27,8 +30,14 @@ func ForwardQuery(query *dns.Msg, config string, nocache bool) *dns.Msg {
 	if !nocache {
 		if cached := GetDomainFromCache(lfqdn); cached != nil {
 			go incrementStats("CacheHit", 1)
+			Rcode := cached.MsgHdr.Rcode
 			cached.SetReply(query)
+			cached.MsgHdr.Rcode = Rcode
 			cached.Authoritative = true
+			if ZabovDebug {
+				log.Println("ForwardQuery: CacheHit")
+			}
+			cached.Compress = true
 			return cached
 
 		}
@@ -42,7 +51,8 @@ func ForwardQuery(query *dns.Msg, config string, nocache bool) *dns.Msg {
 	for {
 		// round robin with retry
 
-		if !NetworkUp {
+		// local responder should always be available also if no internet connection
+		if !NetworkUp && localresponderConfigName != config {
 			time.Sleep(10 * time.Second)
 			go incrementStats("Network Problems ", 1)
 			continue
@@ -57,9 +67,16 @@ func ForwardQuery(query *dns.Msg, config string, nocache bool) *dns.Msg {
 			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!")
+			}
+
 			return in
 
 		}

dns_handler.go

@@ -269,7 +269,7 @@ func (mydns *handler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 		if len(ZabovLocalResponder) > 0 {
 			if !strings.Contains(fqdn, ".") ||
 				(len(ZabovLocalDomain) > 0 && strings.HasSuffix(fqdn, ZabovLocalDomain)) {
-				config = "__localresponder__"
+				config = localresponderConfigName
 				ret := ForwardQuery(r, config, true)
 				w.WriteMsg(ret)
 				go logQuery(remIP, fqdn, QType, config, timetable, "localresponder")
@@ -282,12 +282,12 @@ func (mydns *handler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 
 			msg.Answer = append(msg.Answer, &dns.A{
 				Hdr: dns.RR_Header{Name: domain, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 60},
-				A:   net.ParseIP(ZabovConfig.ZabovAddBL),
+				A:   ZabovConfig.ZabovAddBL,
 			})
 			go logQuery(remIP, fqdn, QType, config, timetable, "killed")
 		} else {
 			go logQuery(remIP, fqdn, QType, config, timetable, "forwarded")
-			ret := ForwardQuery(r, config, false)
+			ret := ForwardQuery(r, config, !ZabovConfig.ZabovCache)
 			w.WriteMsg(ret)
 		}
 	case dns.TypePTR:
@@ -297,13 +297,13 @@ func (mydns *handler) ServeDNS(w dns.ResponseWriter, r *dns.Msg) {
 
 		if len(ZabovLocalResponder) > 0 {
 			// if set use local responder for reverse lookup (suffix ".in-addr.arpa.")
-			config = "__localresponder__"
+			config = localresponderConfigName
 		}
 		ret := ForwardQuery(r, config, true)
 		w.WriteMsg(ret)
 		go logQuery(remIP, msg.Question[0].Name, QType, config, timetable, "localresponder")
 	default:
-		ret := ForwardQuery(r, config, false)
+		ret := ForwardQuery(r, config, !ZabovConfig.ZabovCache)
 		w.WriteMsg(ret)
 		if len(ZabovDebugDBPath) > 0 {
 			go logQuery(remIP, msg.Question[0].Name, QType, config, timetable, "forwarded")

main.go

@@ -37,10 +37,11 @@ type handler struct{}
 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     string   // json:blackholeip  -> ZabovAddBL is the IP we want to send all the clients to. Usually is 127.0.0.1
+	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
 	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
 }