github.com/bugfan/wireguard-go@v0.0.0-20230720020150-a7b2fa340c66/conn/conn.go (about)

     1  /* SPDX-License-Identifier: MIT
     2   *
     3   * Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
     4   */
     5  
     6  // Package conn implements WireGuard's network connections.
     7  package conn
     8  
     9  import (
    10  	"errors"
    11  	"fmt"
    12  	"net"
    13  	"reflect"
    14  	"runtime"
    15  	"strings"
    16  )
    17  
    18  // A ReceiveFunc receives a single inbound packet from the network.
    19  // It writes the data into b. n is the length of the packet.
    20  // ep is the remote endpoint.
    21  type ReceiveFunc func(b []byte) (n int, ep Endpoint, err error)
    22  
    23  // A Bind listens on a port for both IPv6 and IPv4 UDP traffic.
    24  //
    25  // A Bind interface may also be a PeekLookAtSocketFd or BindSocketToInterface,
    26  // depending on the platform-specific implementation.
    27  type Bind interface {
    28  	// Open puts the Bind into a listening state on a given port and reports the actual
    29  	// port that it bound to. Passing zero results in a random selection.
    30  	// fns is the set of functions that will be called to receive packets.
    31  	Open(port uint16) (fns []ReceiveFunc, actualPort uint16, err error)
    32  
    33  	// Close closes the Bind listener.
    34  	// All fns returned by Open must return net.ErrClosed after a call to Close.
    35  	Close() error
    36  
    37  	// SetMark sets the mark for each packet sent through this Bind.
    38  	// This mark is passed to the kernel as the socket option SO_MARK.
    39  	SetMark(mark uint32) error
    40  
    41  	// Send writes a packet b to address ep.
    42  	Send(b []byte, ep Endpoint) error
    43  
    44  	// ParseEndpoint creates a new endpoint from a string.
    45  	ParseEndpoint(s string) (Endpoint, error)
    46  }
    47  
    48  // BindSocketToInterface is implemented by Bind objects that support being
    49  // tied to a single network interface. Used by wireguard-windows.
    50  type BindSocketToInterface interface {
    51  	BindSocketToInterface4(interfaceIndex uint32, blackhole bool) error
    52  	BindSocketToInterface6(interfaceIndex uint32, blackhole bool) error
    53  }
    54  
    55  // PeekLookAtSocketFd is implemented by Bind objects that support having their
    56  // file descriptor peeked at. Used by wireguard-android.
    57  type PeekLookAtSocketFd interface {
    58  	PeekLookAtSocketFd4() (fd int, err error)
    59  	PeekLookAtSocketFd6() (fd int, err error)
    60  }
    61  
    62  // An Endpoint maintains the source/destination caching for a peer.
    63  //
    64  //	dst: the remote address of a peer ("endpoint" in uapi terminology)
    65  //	src: the local address from which datagrams originate going to the peer
    66  type Endpoint interface {
    67  	ClearSrc()           // clears the source address
    68  	SrcToString() string // returns the local source address (ip:port)
    69  	DstToString() string // returns the destination address (ip:port)
    70  	DstToBytes() []byte  // used for mac2 cookie calculations
    71  	DstIP() net.IP
    72  	SrcIP() net.IP
    73  }
    74  
    75  var (
    76  	ErrBindAlreadyOpen   = errors.New("bind is already open")
    77  	ErrWrongEndpointType = errors.New("endpoint type does not correspond with bind type")
    78  )
    79  
    80  func (fn ReceiveFunc) PrettyName() string {
    81  	name := runtime.FuncForPC(reflect.ValueOf(fn).Pointer()).Name()
    82  	// 0. cheese/taco.beansIPv6.func12.func21218-fm
    83  	name = strings.TrimSuffix(name, "-fm")
    84  	// 1. cheese/taco.beansIPv6.func12.func21218
    85  	if idx := strings.LastIndexByte(name, '/'); idx != -1 {
    86  		name = name[idx+1:]
    87  		// 2. taco.beansIPv6.func12.func21218
    88  	}
    89  	for {
    90  		var idx int
    91  		for idx = len(name) - 1; idx >= 0; idx-- {
    92  			if name[idx] < '0' || name[idx] > '9' {
    93  				break
    94  			}
    95  		}
    96  		if idx == len(name)-1 {
    97  			break
    98  		}
    99  		const dotFunc = ".func"
   100  		if !strings.HasSuffix(name[:idx+1], dotFunc) {
   101  			break
   102  		}
   103  		name = name[:idx+1-len(dotFunc)]
   104  		// 3. taco.beansIPv6.func12
   105  		// 4. taco.beansIPv6
   106  	}
   107  	if idx := strings.LastIndexByte(name, '.'); idx != -1 {
   108  		name = name[idx+1:]
   109  		// 5. beansIPv6
   110  	}
   111  	if name == "" {
   112  		return fmt.Sprintf("%p", fn)
   113  	}
   114  	if strings.HasSuffix(name, "IPv4") {
   115  		return "v4"
   116  	}
   117  	if strings.HasSuffix(name, "IPv6") {
   118  		return "v6"
   119  	}
   120  	return name
   121  }
   122  
   123  func parseEndpoint(s string) (*net.UDPAddr, error) {
   124  	// ensure that the host is an IP address
   125  
   126  	host, _, err := net.SplitHostPort(s)
   127  	if err != nil {
   128  		return nil, err
   129  	}
   130  	if i := strings.LastIndexByte(host, '%'); i > 0 && strings.IndexByte(host, ':') >= 0 {
   131  		// Remove the scope, if any. ResolveUDPAddr below will use it, but here we're just
   132  		// trying to make sure with a small sanity test that this is a real IP address and
   133  		// not something that's likely to incur DNS lookups.
   134  		host = host[:i]
   135  	}
   136  	if ip := net.ParseIP(host); ip == nil {
   137  		return nil, errors.New("Failed to parse IP address: " + host)
   138  	}
   139  
   140  	// parse address and port
   141  
   142  	addr, err := net.ResolveUDPAddr("udp", s)
   143  	if err != nil {
   144  		return nil, err
   145  	}
   146  	ip4 := addr.IP.To4()
   147  	if ip4 != nil {
   148  		addr.IP = ip4
   149  	}
   150  	return addr, err
   151  }