Disable IPv4 defragmentation and support IPv6 (#487)

* Remove the extra negation on `nodefrag` flag's value

* Support IPv4 fragmentation and IPv6 at the same time

* Re-enable `nodefrag` flag

shared/kubernetes/provider.go

@@ -6,12 +6,16 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
+	"net/url"
+	"path/filepath"
+	"regexp"
+
 	"github.com/op/go-logging"
 	"github.com/up9inc/mizu/shared"
 	"github.com/up9inc/mizu/shared/logger"
 	"github.com/up9inc/mizu/shared/semver"
 	"github.com/up9inc/mizu/tap/api"
-	"io"
 	v1 "k8s.io/api/apps/v1"
 	core "k8s.io/api/core/v1"
 	rbac "k8s.io/api/rbac/v1"
@@ -32,9 +36,6 @@ import (
 	"k8s.io/client-go/tools/cache"
 	"k8s.io/client-go/tools/clientcmd"
 	watchtools "k8s.io/client-go/tools/watch"
-	"net/url"
-	"path/filepath"
-	"regexp"
 )
 
 type Provider struct {

tap/source/tcp_packet_source.go

@@ -121,11 +121,8 @@ func (source *tcpPacketSource) readPackets(ipdefrag bool, packets chan<- TcpPack
 		}
 
 		// defrag the IPv4 packet if required
-		if !ipdefrag {
+		if ipdefrag {
-			ip4Layer := packet.Layer(layers.LayerTypeIPv4)
+			if ip4Layer := packet.Layer(layers.LayerTypeIPv4); ip4Layer != nil {
-			if ip4Layer == nil {
-				continue
-			}
 				ip4 := ip4Layer.(*layers.IPv4)
 				l := ip4.Length
 				newip4, err := source.defragger.DefragIPv4(ip4)
@@ -146,6 +143,7 @@ func (source *tcpPacketSource) readPackets(ipdefrag bool, packets chan<- TcpPack
 					_ = nextDecoder.Decode(newip4.Payload, pb)
 				}
 			}
+		}
 
 		packets <- TcpPacketInfo{
 			Packet: packet,