github.com/sagernet/netlink@v0.0.0-20240612041022-b9a21c07ac6a/xfrm_monitor_linux.go (about)

     1  package netlink
     2  
     3  import (
     4  	"fmt"
     5  
     6  	"github.com/sagernet/netlink/nl"
     7  	"github.com/vishvananda/netns"
     8  	"golang.org/x/sys/unix"
     9  )
    10  
    11  type XfrmMsg interface {
    12  	Type() nl.XfrmMsgType
    13  }
    14  
    15  type XfrmMsgExpire struct {
    16  	XfrmState *XfrmState
    17  	Hard      bool
    18  }
    19  
    20  func (ue *XfrmMsgExpire) Type() nl.XfrmMsgType {
    21  	return nl.XFRM_MSG_EXPIRE
    22  }
    23  
    24  func parseXfrmMsgExpire(b []byte) *XfrmMsgExpire {
    25  	var e XfrmMsgExpire
    26  
    27  	msg := nl.DeserializeXfrmUserExpire(b)
    28  	e.XfrmState = xfrmStateFromXfrmUsersaInfo(&msg.XfrmUsersaInfo)
    29  	e.Hard = msg.Hard == 1
    30  
    31  	return &e
    32  }
    33  
    34  func XfrmMonitor(ch chan<- XfrmMsg, done <-chan struct{}, errorChan chan<- error,
    35  	types ...nl.XfrmMsgType) error {
    36  
    37  	groups, err := xfrmMcastGroups(types)
    38  	if err != nil {
    39  		return nil
    40  	}
    41  	s, err := nl.SubscribeAt(netns.None(), netns.None(), unix.NETLINK_XFRM, groups...)
    42  	if err != nil {
    43  		return err
    44  	}
    45  
    46  	if done != nil {
    47  		go func() {
    48  			<-done
    49  			s.Close()
    50  		}()
    51  
    52  	}
    53  
    54  	go func() {
    55  		defer close(ch)
    56  		for {
    57  			msgs, from, err := s.Receive()
    58  			if err != nil {
    59  				errorChan <- err
    60  				return
    61  			}
    62  			if from.Pid != nl.PidKernel {
    63  				errorChan <- fmt.Errorf("Wrong sender portid %d, expected %d", from.Pid, nl.PidKernel)
    64  				return
    65  			}
    66  			for _, m := range msgs {
    67  				switch m.Header.Type {
    68  				case nl.XFRM_MSG_EXPIRE:
    69  					ch <- parseXfrmMsgExpire(m.Data)
    70  				default:
    71  					errorChan <- fmt.Errorf("unsupported msg type: %x", m.Header.Type)
    72  				}
    73  			}
    74  		}
    75  	}()
    76  
    77  	return nil
    78  }
    79  
    80  func xfrmMcastGroups(types []nl.XfrmMsgType) ([]uint, error) {
    81  	groups := make([]uint, 0)
    82  
    83  	if len(types) == 0 {
    84  		return nil, fmt.Errorf("no xfrm msg type specified")
    85  	}
    86  
    87  	for _, t := range types {
    88  		var group uint
    89  
    90  		switch t {
    91  		case nl.XFRM_MSG_EXPIRE:
    92  			group = nl.XFRMNLGRP_EXPIRE
    93  		default:
    94  			return nil, fmt.Errorf("unsupported group: %x", t)
    95  		}
    96  
    97  		groups = append(groups, group)
    98  	}
    99  
   100  	return groups, nil
   101  }