all: imp client resolving

internal/dnsforward/config.go

@@ -270,7 +270,10 @@ type ServerConfig struct {
 	UDPListenAddrs []*net.UDPAddr        // UDP listen address
 	TCPListenAddrs []*net.TCPAddr        // TCP listen address
 	UpstreamConfig *proxy.UpstreamConfig // Upstream DNS servers config
-	OnDNSRequest   func(d *proxy.DNSContext)
+
+	// ClientIPs, if not nil, is used to send clients' IP addresses to other
+	// parts of AdGuard Home that may use it for resolving rDNS, WHOIS, etc.
+	ClientIPs chan netip.Addr
 
 	FilteringConfig
 	TLSConfig

internal/dnsforward/dnsforward.go

@@ -99,6 +99,10 @@ type Server struct {
 	// must be a valid domain name plus dots on each side.
 	localDomainSuffix string
 
+	// ClientIPs, if not nil, is used to send clients' IP addresses to other
+	// parts of AdGuard Home that may use it for resolving rDNS, WHOIS, etc.
+	clientIPs chan<- netip.Addr
+
 	ipset          ipsetCtx
 	privateNets    netutil.SubnetSet
 	localResolvers *proxy.Proxy
@@ -318,7 +322,8 @@ func (s *Server) Exchange(ip netip.Addr) (host string, err error) {
 			Qclass: dns.ClassINET,
 		}},
 	}
-	ctx := &proxy.DNSContext{
+
+	dctx := &proxy.DNSContext{
 		Proto:     "udp",
 		Req:       req,
 		StartTime: time.Now(),
@@ -336,11 +341,11 @@ func (s *Server) Exchange(ip netip.Addr) (host string, err error) {
 		resolver = s.internalProxy
 	}
 
-	if err = resolver.Resolve(ctx); err != nil {
+	if err = resolver.Resolve(dctx); err != nil {
 		return "", err
 	}
 
-	return hostFromPTR(ctx.Res)
+	return hostFromPTR(dctx.Res)
 }
 
 // hostFromPTR returns domain name from the PTR response or error.
@@ -555,6 +560,8 @@ func (s *Server) Prepare(conf *ServerConfig) (err error) {
 
 	s.recDetector.clear()
 
+	s.clientIPs = s.conf.ClientIPs
+
 	return nil
 }
 
@@ -696,6 +703,9 @@ func (s *Server) Reconfigure(conf *ServerConfig) error {
 	// TODO(a.garipov): This whole piece of API is weird and needs to be remade.
 	if conf == nil {
 		conf = &s.conf
+	} else if s.clientIPs != nil {
+		close(s.clientIPs)
+		s.clientIPs = nil
 	}
 
 	err = s.Prepare(conf)

internal/dnsforward/process.go

@@ -30,6 +30,7 @@ type dnsContext struct {
 	setts *filtering.Settings
 
 	result *filtering.Result
+
 	// origResp is the response received from upstream.  It is set when the
 	// response is modified by filters.
 	origResp *dns.Msg
@@ -48,13 +49,13 @@ type dnsContext struct {
 	// clientID is the ClientID from DoH, DoQ, or DoT, if provided.
 	clientID string
 
+	// startTime is the time at which the processing of the request has started.
+	startTime time.Time
+
 	// origQuestion is the question received from the client.  It is set
 	// when the request is modified by rewrites.
 	origQuestion dns.Question
 
-	// startTime is the time at which the processing of the request has started.
-	startTime time.Time
-
 	// protectionEnabled shows if the filtering is enabled, and if the
 	// server's DNS filter is ready.
 	protectionEnabled bool
@@ -177,9 +178,7 @@ func (s *Server) processInitial(dctx *dnsContext) (rc resultCode) {
 		return resultCodeFinish
 	}
 
-	if s.conf.OnDNSRequest != nil {
-		s.conf.OnDNSRequest(pctx)
-	}
+	s.processClientIP(pctx.Addr)
 
 	// Disable Mozilla DoH.
 	//
@@ -218,6 +217,28 @@ func (s *Server) processInitial(dctx *dnsContext) (rc resultCode) {
 	return resultCodeSuccess
 }
 
+// processClientIP sends the client IP address to s.clientIPs, if needed.
+func (s *Server) processClientIP(addr net.Addr) {
+	clientIP := netutil.NetAddrToAddrPort(addr).Addr()
+	if clientIP == (netip.Addr{}) {
+		log.Info("dnsforward: warning: bad client addr %q", addr)
+
+		return
+	}
+
+	// Do not assign s.clientIPs to a local variable to then use, since this
+	// lock also serializes the closure of s.clientIPs.
+	s.serverLock.RLock()
+	defer s.serverLock.RUnlock()
+
+	select {
+	case s.clientIPs <- clientIP:
+		// Go on.
+	default:
+		log.Debug("dnsforward: client ip channel is nil or full; len: %d", len(s.clientIPs))
+	}
+}
+
 func (s *Server) setTableHostToIP(t hostToIPTable) {
 	s.tableHostToIPLock.Lock()
 	defer s.tableHostToIPLock.Unlock()