correct handle corner cases

Signed-off-by: Denis Tingaikin <denis.tingajkin@xored.com>

pkg/networkservice/chains/nsmgr/vl3_test.go

@@ -23,7 +23,6 @@ import (
 	"context"
 	"fmt"
 	"net"
-	"net/url"
 	"testing"
 	"time"
 
@@ -40,6 +39,12 @@ import (
 	"github.com/networkservicemesh/sdk/pkg/tools/sandbox"
 )
 
+func staticIP(addr net.IP) func() net.IP {
+	return func() net.IP {
+		return addr
+	}
+}
+
 func Test_NSC_ConnectsTo_vl3NSE(t *testing.T) {
 	t.Cleanup(func() { goleak.VerifyNone(t) })
 
@@ -70,7 +75,7 @@ func Test_NSC_ConnectsTo_vl3NSE(t *testing.T) {
 		sandbox.GenerateTestToken,
 		vl3.NewServer(ctx, serverPrefixCh),
 		vl3dns.NewServer(ctx,
-			&url.URL{Scheme: "tcp", Host: "127.0.0.1"},
+			staticIP(net.ParseIP("127.0.0.1")),
 			vl3dns.WithDomainSchemes("{{ index .Labels \"podName\" }}.{{ .NetworkService }}."),
 			vl3dns.WithDNSPort(40053)),
 	)
@@ -161,7 +166,7 @@ func Test_vl3NSE_ConnectsTo_vl3NSE(t *testing.T) {
 		sandbox.GenerateTestToken,
 		vl3.NewServer(ctx, serverPrefixCh),
 		vl3dns.NewServer(ctx,
-			&url.URL{Scheme: "tcp", Host: "127.0.0.1"},
+			staticIP(net.ParseIP("127.0.0.1")),
 			vl3dns.WithDomainSchemes("{{ index .Labels \"podName\" }}.{{ .NetworkService }}."),
 			vl3dns.WithDNSListenAndServeFunc(func(ctx context.Context, handler dnsutils.Handler, listenOn string) {
 				dnsutils.ListenAndServe(ctx, handler, ":50053")
@@ -182,7 +187,7 @@ func Test_vl3NSE_ConnectsTo_vl3NSE(t *testing.T) {
 	defer close(clientPrefixCh)
 
 	clientPrefixCh <- &ipam.PrefixResponse{Prefix: "127.0.0.1/32"}
-	nsc := domain.Nodes[0].NewClient(ctx, sandbox.GenerateTestToken, client.WithAdditionalFunctionality(vl3.NewClient(ctx, clientPrefixCh), vl3dns.NewClient(&url.URL{Host: "127.0.0.1"})))
+	nsc := domain.Nodes[0].NewClient(ctx, sandbox.GenerateTestToken, client.WithAdditionalFunctionality(vl3.NewClient(ctx, clientPrefixCh), vl3dns.NewClient(net.ParseIP("127.0.0.1"))))
 
 	req := defaultRequest(nsReg.Name)
 	req.Connection.Id = uuid.New().String()

pkg/networkservice/connectioncontext/dnscontext/vl3dns/client.go

@@ -18,7 +18,7 @@ package vl3dns
 
 import (
 	"context"
-	"net/url"
+	"net"
 
 	"github.com/golang/protobuf/ptypes/empty"
 	"github.com/networkservicemesh/api/pkg/api/networkservice"
@@ -28,14 +28,14 @@ import (
 )
 
 type vl3DNSClient struct {
-	listenOn *url.URL
+	dnsServerIP net.IP
 }
 
 // NewClient - returns a new null client that does nothing but call next.Client(ctx).{Request/Close} and return the result
 //             This is very useful in testing
-func NewClient(listenOn *url.URL) networkservice.NetworkServiceClient {
+func NewClient(dnsServerIP net.IP) networkservice.NetworkServiceClient {
 	return &vl3DNSClient{
-		listenOn: listenOn,
+		dnsServerIP: dnsServerIP,
 	}
 }
 
@@ -52,7 +52,7 @@ func (n *vl3DNSClient) Request(ctx context.Context, request *networkservice.Netw
 
 	request.GetConnection().GetContext().GetDnsContext().Configs = []*networkservice.DNSConfig{
 		{
-			DnsServerIps: []string{n.listenOn.Hostname()},
+			DnsServerIps: []string{n.dnsServerIP.String()},
 		},
 	}
 	return next.Client(ctx).Request(ctx, request, opts...)

pkg/networkservice/connectioncontext/dnscontext/vl3dns/server.go

@@ -37,6 +37,7 @@ import (
 	dnsnext "github.com/networkservicemesh/sdk/pkg/tools/dnsutils/next"
 	"github.com/networkservicemesh/sdk/pkg/tools/dnsutils/noloop"
 	"github.com/networkservicemesh/sdk/pkg/tools/dnsutils/norecursion"
+	"github.com/networkservicemesh/sdk/pkg/tools/ippool"
 )
 
 type vl3DNSServer struct {
@@ -47,7 +48,7 @@ type vl3DNSServer struct {
 	dnsPort               int
 	dnsServer             dnsutils.Handler
 	listenAndServeDNS     func(ctx context.Context, handler dnsutils.Handler, listenOn string)
-	listenOn              *url.URL
+	getDNSServerIP        func() net.IP
 }
 
 type clientDNSNameKey struct{}
@@ -57,11 +58,11 @@ type clientDNSNameKey struct{}
 // By default is using fanout dns handler to connect to other vl3 nses.
 // chanCtx is using for signal to stop dns server.
 // opts confugre vl3dns networkservice instance with specific behavior.
-func NewServer(chanCtx context.Context, listenOn *url.URL, opts ...Option) networkservice.NetworkServiceServer {
+func NewServer(chanCtx context.Context, getDNSServerIP func() net.IP, opts ...Option) networkservice.NetworkServiceServer {
 	var result = &vl3DNSServer{
 		dnsPort:           53,
 		listenAndServeDNS: dnsutils.ListenAndServe,
-		listenOn:          listenOn,
+		getDNSServerIP:    getDNSServerIP,
 	}
 
 	for _, opt := range opts {
@@ -89,15 +90,20 @@ func (n *vl3DNSServer) Request(ctx context.Context, request *networkservice.Netw
 
 	var dnsContext = request.GetConnection().GetContext().GetDnsContext()
 
-	for _, config := range dnsContext.GetConfigs() {
-		for _, serverIP := range config.DnsServerIps {
-			var u = url.URL{Scheme: "tcp", Host: fmt.Sprintf("%v:%v", serverIP, n.dnsPort)}
-			n.fanoutAddresses.Store(u, struct{}{})
+	if srcRoutes := request.GetConnection().GetContext().GetIpContext().GetSrcIPRoutes(); len(srcRoutes) > 0 {
+		var lastPrefix = srcRoutes[len(srcRoutes)-1].Prefix
+		for _, config := range dnsContext.GetConfigs() {
+			for _, serverIP := range config.DnsServerIps {
+				if withinPrefix(serverIP, lastPrefix) {
+					var u = url.URL{Scheme: "tcp", Host: fmt.Sprintf("%v:%v", serverIP, n.dnsPort)}
+					n.fanoutAddresses.Store(u, struct{}{})
+				}
+			}
 		}
 	}
 
 	dnsContext.Configs = append(dnsContext.Configs, &networkservice.DNSConfig{
-		DnsServerIps: []string{n.listenOn.Hostname()},
+		DnsServerIps: []string{n.getDNSServerIP().String()},
 	})
 
 	var recordNames, err = n.buildSrcDNSRecords(request.GetConnection())
@@ -178,3 +184,12 @@ func compareStringSlices(a, b []string) bool {
 	}
 	return true
 }
+
+func withinPrefix(ipAddr, prefix string) bool {
+	_, ipNet, err := net.ParseCIDR(prefix)
+	if err != nil {
+		return false
+	}
+	var pool = ippool.NewWithNet(ipNet)
+	return pool.ContainsString(ipAddr)
+}