listen_posix.go

Documentation: golang.org/x/net/icmp

     1  // Copyright 2014 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || windows
     6  
     7  package icmp
     8  
     9  import (
    10  	"net"
    11  	"os"
    12  	"runtime"
    13  	"syscall"
    14  
    15  	"golang.org/x/net/internal/iana"
    16  	"golang.org/x/net/ipv4"
    17  	"golang.org/x/net/ipv6"
    18  )
    19  
    20  const sysIP_STRIPHDR = 0x17 // for now only darwin supports this option
    21  
    22  // ListenPacket listens for incoming ICMP packets addressed to
    23  // address. See net.Dial for the syntax of address.
    24  //
    25  // For non-privileged datagram-oriented ICMP endpoints, network must
    26  // be "udp4" or "udp6". The endpoint allows to read, write a few
    27  // limited ICMP messages such as echo request and echo reply.
    28  // Currently only Darwin and Linux support this.
    29  //
    30  // Examples:
    31  //
    32  //	ListenPacket("udp4", "192.168.0.1")
    33  //	ListenPacket("udp4", "0.0.0.0")
    34  //	ListenPacket("udp6", "fe80::1%en0")
    35  //	ListenPacket("udp6", "::")
    36  //
    37  // For privileged raw ICMP endpoints, network must be "ip4" or "ip6"
    38  // followed by a colon and an ICMP protocol number or name.
    39  //
    40  // Examples:
    41  //
    42  //	ListenPacket("ip4:icmp", "192.168.0.1")
    43  //	ListenPacket("ip4:1", "0.0.0.0")
    44  //	ListenPacket("ip6:ipv6-icmp", "fe80::1%en0")
    45  //	ListenPacket("ip6:58", "::")
    46  func ListenPacket(network, address string) (*PacketConn, error) {
    47  	var family, proto int
    48  	switch network {
    49  	case "udp4":
    50  		family, proto = syscall.AF_INET, iana.ProtocolICMP
    51  	case "udp6":
    52  		family, proto = syscall.AF_INET6, iana.ProtocolIPv6ICMP
    53  	default:
    54  		i := last(network, ':')
    55  		if i < 0 {
    56  			i = len(network)
    57  		}
    58  		switch network[:i] {
    59  		case "ip4":
    60  			proto = iana.ProtocolICMP
    61  		case "ip6":
    62  			proto = iana.ProtocolIPv6ICMP
    63  		}
    64  	}
    65  	var cerr error
    66  	var c net.PacketConn
    67  	switch family {
    68  	case syscall.AF_INET, syscall.AF_INET6:
    69  		s, err := syscall.Socket(family, syscall.SOCK_DGRAM, proto)
    70  		if err != nil {
    71  			return nil, os.NewSyscallError("socket", err)
    72  		}
    73  		if (runtime.GOOS == "darwin" || runtime.GOOS == "ios") && family == syscall.AF_INET {
    74  			if err := syscall.SetsockoptInt(s, iana.ProtocolIP, sysIP_STRIPHDR, 1); err != nil {
    75  				syscall.Close(s)
    76  				return nil, os.NewSyscallError("setsockopt", err)
    77  			}
    78  		}
    79  		sa, err := sockaddr(family, address)
    80  		if err != nil {
    81  			syscall.Close(s)
    82  			return nil, err
    83  		}
    84  		if err := syscall.Bind(s, sa); err != nil {
    85  			syscall.Close(s)
    86  			return nil, os.NewSyscallError("bind", err)
    87  		}
    88  		f := os.NewFile(uintptr(s), "datagram-oriented icmp")
    89  		c, cerr = net.FilePacketConn(f)
    90  		f.Close()
    91  	default:
    92  		c, cerr = net.ListenPacket(network, address)
    93  	}
    94  	if cerr != nil {
    95  		return nil, cerr
    96  	}
    97  	switch proto {
    98  	case iana.ProtocolICMP:
    99  		return &PacketConn{c: c, p4: ipv4.NewPacketConn(c)}, nil
   100  	case iana.ProtocolIPv6ICMP:
   101  		return &PacketConn{c: c, p6: ipv6.NewPacketConn(c)}, nil
   102  	default:
   103  		return &PacketConn{c: c}, nil
   104  	}
   105  }
   106
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