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