internal/authoritative.go

@@ -124,5 +124,7 @@ func handleRequest(w dns.ResponseWriter, r *dns.Msg, zone zoneView) {
 		m.SetRcode(m, dns.RcodeNameError)
 	}
 
+	debugResponse(m)
+
 	w.WriteMsg(m)
 }

internal/cooldns.go

@@ -18,6 +18,13 @@ type zoneMap map[string][]zoneView
 
 // Start starts cooldns
 func Start(configPath string) {
+
+	debug := os.Getenv("COOLDNS_DEBUG")
+	if len(debug) != 0 {
+		debugFlag = true
+		debugLog("Enabled debug")
+	}
+
 	config, err := loadConfig(configPath)
 	if err != nil {
 		log.Fatalf("Failed to load config: %s\n", err.Error())
@@ -80,6 +87,8 @@ func createServer(zones zoneMap, config config, aclList map[string]*net.IPNet, b
 			return
 		}
 
+		debugRequest(r, ip)
+
 		// Check if it is a ACME DNS-01 challange
 		if config.Lego.Enable && handleACMERequest(w, r, acmeList) {
 			return
@@ -96,6 +105,7 @@ func createServer(zones zoneMap, config config, aclList map[string]*net.IPNet, b
 			handleBlockedDomain(w, r)
 		} else {
 			// Forward request
+			debugLog("Forwarded request")
 			in, _, err := c.Exchange(r, config.Forward.Server)
 
 			if err != nil {
@@ -167,6 +177,8 @@ func createHandler(zones []zoneView, config config, aclList map[string]*net.IPNe
 			return
 		}
 
+		debugRequest(r, ip)
+
 		// Check if it is a ACME DNS-01 challange
 		if config.Lego.Enable && handleACMERequest(w, r, acmeList) {
 			return

internal/debug.go

@@ -0,0 +1,35 @@
+package cooldns
+
+import (
+	"fmt"
+	"log"
+	"net"
+
+	"github.com/miekg/dns"
+)
+
+var debugFlag = false
+
+func debugLog(msg string) {
+	if !debugFlag {
+		return
+	}
+
+	log.Printf("DEBUG: %s", msg)
+}
+
+func debugRequest(r *dns.Msg, ip net.IP) {
+	if !debugFlag {
+		return
+	}
+
+	debugLog(fmt.Sprintf("Request from %s: %s", ip, r.String()))
+}
+
+func debugResponse(m *dns.Msg) {
+	if !debugFlag {
+		return
+	}
+
+	debugLog(fmt.Sprintf("Response send: %s", m.String()))
+}