Add support for tcp diags.

link_linux.go

@@ -29,7 +29,6 @@ const (
 	TUNTAP_ONE_QUEUE TuntapFlag = syscall.IFF_ONE_QUEUE
 )
 
-var native = nl.NativeEndian()
 var lookupByDump = false
 
 var macvlanModes = [...]uint32{
@@ -1443,26 +1442,6 @@ func linkFlags(rawFlags uint32) net.Flags {
 	return f
 }
 
-func htonl(val uint32) []byte {
-	bytes := make([]byte, 4)
-	binary.BigEndian.PutUint32(bytes, val)
-	return bytes
-}
-
-func htons(val uint16) []byte {
-	bytes := make([]byte, 2)
-	binary.BigEndian.PutUint16(bytes, val)
-	return bytes
-}
-
-func ntohl(buf []byte) uint32 {
-	return binary.BigEndian.Uint32(buf)
-}
-
-func ntohs(buf []byte) uint16 {
-	return binary.BigEndian.Uint16(buf)
-}
-
 func addGretapAttrs(gretap *Gretap, linkInfo *nl.RtAttr) {
 	data := nl.NewRtAttrChild(linkInfo, nl.IFLA_INFO_DATA, nil)
 

netlink.go

@@ -8,7 +8,15 @@
 // interface that is loosly modeled on the iproute2 cli.
 package netlink
 
-import "net"
+import (
+	"errors"
+	"net"
+)
+
+var (
+	// ErrNotImplemented is returned when a requested feature is not implemented.
+	ErrNotImplemented = errors.New("not implemented")
+)
 
 // ParseIPNet parses a string in ip/net format and returns a net.IPNet.
 // This is valuable because addresses in netlink are often IPNets and

netlink_unspecified.go

@@ -2,14 +2,7 @@
 
 package netlink
 
-import (
+import "net"
-	"errors"
-	"net"
-)
-
-var (
-	ErrNotImplemented = errors.New("not implemented")
-)
 
 func LinkSetUp(link Link) error {
 	return ErrNotImplemented
@@ -214,3 +207,7 @@ func NeighList(linkIndex, family int) ([]Neigh, error) {
 func NeighDeserialize(m []byte) (*Neigh, error) {
 	return nil, ErrNotImplemented
 }
+
+func SocketGet(local, remote net.Addr) (*Socket, error) {
+	return nil, ErrNotImplemented
+}

nl/syscall.go

@@ -35,3 +35,9 @@ const (
 	FR_ACT_UNREACHABLE /* Drop with ENETUNREACH */
 	FR_ACT_PROHIBIT    /* Drop with EACCES */
 )
+
+// socket diags related
+const (
+	SOCK_DIAG_BY_FAMILY = 20         /* linux.sock_diag.h */
+	TCPDIAG_NOCOOKIE    = 0xFFFFFFFF /* TCPDIAG_NOCOOKIE in net/ipv4/tcp_diag.h*/
+)

order.go

@@ -0,0 +1,32 @@
+package netlink
+
+import (
+	"encoding/binary"
+
+	"github.com/vishvananda/netlink/nl"
+)
+
+var (
+	native       = nl.NativeEndian()
+	networkOrder = binary.BigEndian
+)
+
+func htonl(val uint32) []byte {
+	bytes := make([]byte, 4)
+	binary.BigEndian.PutUint32(bytes, val)
+	return bytes
+}
+
+func htons(val uint16) []byte {
+	bytes := make([]byte, 2)
+	binary.BigEndian.PutUint16(bytes, val)
+	return bytes
+}
+
+func ntohl(buf []byte) uint32 {
+	return binary.BigEndian.Uint32(buf)
+}
+
+func ntohs(buf []byte) uint16 {
+	return binary.BigEndian.Uint16(buf)
+}

socket.go

@@ -0,0 +1,27 @@
+package netlink
+
+import "net"
+
+// SocketID identifies a single socket.
+type SocketID struct {
+	SourcePort      uint16
+	DestinationPort uint16
+	Source          net.IP
+	Destination     net.IP
+	Interface       uint32
+	Cookie          [2]uint32
+}
+
+// Socket represents a netlink socket.
+type Socket struct {
+	Family  uint8
+	State   uint8
+	Timer   uint8
+	Retrans uint8
+	ID      SocketID
+	Expires uint32
+	RQueue  uint32
+	WQueue  uint32
+	UID     uint32
+	INode   uint32
+}

socket_linux.go

@@ -0,0 +1,159 @@
+package netlink
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"syscall"
+
+	"github.com/vishvananda/netlink/nl"
+)
+
+const (
+	sizeofSocketID      = 0x30
+	sizeofSocketRequest = sizeofSocketID + 0x8
+	sizeofSocket        = sizeofSocketID + 0x18
+)
+
+type socketRequest struct {
+	Family   uint8
+	Protocol uint8
+	Ext      uint8
+	pad      uint8
+	States   uint32
+	ID       SocketID
+}
+
+type writeBuffer struct {
+	Bytes []byte
+	pos   int
+}
+
+func (b *writeBuffer) Write(c byte) {
+	b.Bytes[b.pos] = c
+	b.pos++
+}
+
+func (b *writeBuffer) Next(n int) []byte {
+	s := b.Bytes[b.pos : b.pos+n]
+	b.pos += n
+	return s
+}
+
+func (r *socketRequest) Serialize() []byte {
+	b := writeBuffer{Bytes: make([]byte, sizeofSocketRequest)}
+	b.Write(r.Family)
+	b.Write(r.Protocol)
+	b.Write(r.Ext)
+	b.Write(r.pad)
+	native.PutUint32(b.Next(4), r.States)
+	networkOrder.PutUint16(b.Next(2), r.ID.SourcePort)
+	networkOrder.PutUint16(b.Next(2), r.ID.DestinationPort)
+	copy(b.Next(4), r.ID.Source.To4())
+	b.Next(12)
+	copy(b.Next(4), r.ID.Destination.To4())
+	b.Next(12)
+	native.PutUint32(b.Next(4), r.ID.Interface)
+	native.PutUint32(b.Next(4), r.ID.Cookie[0])
+	native.PutUint32(b.Next(4), r.ID.Cookie[1])
+	return b.Bytes
+}
+
+func (r *socketRequest) Len() int { return sizeofSocketRequest }
+
+type readBuffer struct {
+	Bytes []byte
+	pos   int
+}
+
+func (b *readBuffer) Read() byte {
+	c := b.Bytes[b.pos]
+	b.pos++
+	return c
+}
+
+func (b *readBuffer) Next(n int) []byte {
+	s := b.Bytes[b.pos : b.pos+n]
+	b.pos += n
+	return s
+}
+
+func (s *Socket) deserialize(b []byte) error {
+	if len(b) < sizeofSocket {
+		return fmt.Errorf("socket data short read (%d); want %d", len(b), sizeofSocket)
+	}
+	rb := readBuffer{Bytes: b}
+	s.Family = rb.Read()
+	s.State = rb.Read()
+	s.Timer = rb.Read()
+	s.Retrans = rb.Read()
+	s.ID.SourcePort = networkOrder.Uint16(rb.Next(2))
+	s.ID.DestinationPort = networkOrder.Uint16(rb.Next(2))
+	s.ID.Source = net.IPv4(rb.Read(), rb.Read(), rb.Read(), rb.Read())
+	rb.Next(12)
+	s.ID.Destination = net.IPv4(rb.Read(), rb.Read(), rb.Read(), rb.Read())
+	rb.Next(12)
+	s.ID.Interface = native.Uint32(rb.Next(4))
+	s.ID.Cookie[0] = native.Uint32(rb.Next(4))
+	s.ID.Cookie[1] = native.Uint32(rb.Next(4))
+	s.Expires = native.Uint32(rb.Next(4))
+	s.RQueue = native.Uint32(rb.Next(4))
+	s.WQueue = native.Uint32(rb.Next(4))
+	s.UID = native.Uint32(rb.Next(4))
+	s.INode = native.Uint32(rb.Next(4))
+	return nil
+}
+
+// SocketGet returns the Socket identified by its local and remote addresses.
+func SocketGet(local, remote net.Addr) (*Socket, error) {
+	localTCP, ok := local.(*net.TCPAddr)
+	if !ok {
+		return nil, ErrNotImplemented
+	}
+	remoteTCP, ok := remote.(*net.TCPAddr)
+	if !ok {
+		return nil, ErrNotImplemented
+	}
+	localIP := localTCP.IP.To4()
+	if localIP == nil {
+		return nil, ErrNotImplemented
+	}
+	remoteIP := remoteTCP.IP.To4()
+	if remoteIP == nil {
+		return nil, ErrNotImplemented
+	}
+
+	s, err := nl.Subscribe(syscall.NETLINK_INET_DIAG)
+	if err != nil {
+		return nil, err
+	}
+	defer s.Close()
+	req := nl.NewNetlinkRequest(nl.SOCK_DIAG_BY_FAMILY, 0)
+	req.AddData(&socketRequest{
+		Family:   syscall.AF_INET,
+		Protocol: syscall.IPPROTO_TCP,
+		ID: SocketID{
+			SourcePort:      uint16(localTCP.Port),
+			DestinationPort: uint16(remoteTCP.Port),
+			Source:          localIP,
+			Destination:     remoteIP,
+			Cookie:          [2]uint32{nl.TCPDIAG_NOCOOKIE, nl.TCPDIAG_NOCOOKIE},
+		},
+	})
+	s.Send(req)
+	msgs, err := s.Receive()
+	if err != nil {
+		return nil, err
+	}
+	if len(msgs) == 0 {
+		return nil, errors.New("no message nor error from netlink")
+	}
+	if len(msgs) > 2 {
+		return nil, fmt.Errorf("multiple (%d) matching sockets", len(msgs))
+	}
+	sock := &Socket{}
+	if err := sock.deserialize(msgs[0].Data); err != nil {
+		return nil, err
+	}
+	return sock, nil
+}

socket_test.go

@@ -0,0 +1,54 @@
+package netlink
+
+import (
+	"log"
+	"net"
+	"os/user"
+	"strconv"
+	"testing"
+)
+
+func TestSocketGet(t *testing.T) {
+	addr, err := net.ResolveTCPAddr("tcp", "localhost:0")
+	if err != nil {
+		log.Fatal(err)
+	}
+	l, err := net.ListenTCP("tcp", addr)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer l.Close()
+
+	conn, err := net.Dial(l.Addr().Network(), l.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	localAddr := conn.LocalAddr().(*net.TCPAddr)
+	remoteAddr := conn.RemoteAddr().(*net.TCPAddr)
+	socket, err := SocketGet(localAddr, remoteAddr)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if got, want := socket.ID.Source, localAddr.IP; !got.Equal(want) {
+		t.Fatalf("local ip = %v, want %v", got, want)
+	}
+	if got, want := socket.ID.Destination, remoteAddr.IP; !got.Equal(want) {
+		t.Fatalf("remote ip = %v, want %v", got, want)
+	}
+	if got, want := int(socket.ID.SourcePort), localAddr.Port; got != want {
+		t.Fatalf("local port = %d, want %d", got, want)
+	}
+	if got, want := int(socket.ID.DestinationPort), remoteAddr.Port; got != want {
+		t.Fatalf("remote port = %d, want %d", got, want)
+	}
+	u, err := user.Current()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got, want := strconv.Itoa(int(socket.UID)), u.Uid; got != want {
+		t.Fatalf("UID = %s, want %s", got, want)
+	}
+}