rawconn_unix_test.go

     1  // Copyright 2017 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 unix
     6  
     7  package net
     8  
     9  import (
    10  	"errors"
    11  	"syscall"
    12  )
    13  
    14  func readRawConn(c syscall.RawConn, b []byte) (int, error) {
    15  	var operr error
    16  	var n int
    17  	err := c.Read(func(s uintptr) bool {
    18  		n, operr = syscall.Read(int(s), b)
    19  		if operr == syscall.EAGAIN {
    20  			return false
    21  		}
    22  		return true
    23  	})
    24  	if err != nil {
    25  		return n, err
    26  	}
    27  	return n, operr
    28  }
    29  
    30  func writeRawConn(c syscall.RawConn, b []byte) error {
    31  	var operr error
    32  	err := c.Write(func(s uintptr) bool {
    33  		_, operr = syscall.Write(int(s), b)
    34  		if operr == syscall.EAGAIN {
    35  			return false
    36  		}
    37  		return true
    38  	})
    39  	if err != nil {
    40  		return err
    41  	}
    42  	return operr
    43  }
    44  
    45  func controlRawConn(c syscall.RawConn, addr Addr) error {
    46  	var operr error
    47  	fn := func(s uintptr) {
    48  		_, operr = syscall.GetsockoptInt(int(s), syscall.SOL_SOCKET, syscall.SO_REUSEADDR)
    49  		if operr != nil {
    50  			return
    51  		}
    52  		switch addr := addr.(type) {
    53  		case *TCPAddr:
    54  			// There's no guarantee that IP-level socket
    55  			// options work well with dual stack sockets.
    56  			// A simple solution would be to take a look
    57  			// at the bound address to the raw connection
    58  			// and to classify the address family of the
    59  			// underlying socket by the bound address:
    60  			//
    61  			// - When IP.To16() != nil and IP.To4() == nil,
    62  			//   we can assume that the raw connection
    63  			//   consists of an IPv6 socket using only
    64  			//   IPv6 addresses.
    65  			//
    66  			// - When IP.To16() == nil and IP.To4() != nil,
    67  			//   the raw connection consists of an IPv4
    68  			//   socket using only IPv4 addresses.
    69  			//
    70  			// - Otherwise, the raw connection is a dual
    71  			//   stack socket, an IPv6 socket using IPv6
    72  			//   addresses including IPv4-mapped or
    73  			//   IPv4-embedded IPv6 addresses.
    74  			if addr.IP.To16() != nil && addr.IP.To4() == nil {
    75  				operr = syscall.SetsockoptInt(int(s), syscall.IPPROTO_IPV6, syscall.IPV6_UNICAST_HOPS, 1)
    76  			} else if addr.IP.To16() == nil && addr.IP.To4() != nil {
    77  				operr = syscall.SetsockoptInt(int(s), syscall.IPPROTO_IP, syscall.IP_TTL, 1)
    78  			}
    79  		}
    80  	}
    81  	if err := c.Control(fn); err != nil {
    82  		return err
    83  	}
    84  	return operr
    85  }
    86  
    87  func controlOnConnSetup(network string, address string, c syscall.RawConn) error {
    88  	var operr error
    89  	var fn func(uintptr)
    90  	switch network {
    91  	case "tcp", "udp", "ip":
    92  		return errors.New("ambiguous network: " + network)
    93  	case "unix", "unixpacket", "unixgram":
    94  		fn = func(s uintptr) {
    95  			_, operr = syscall.GetsockoptInt(int(s), syscall.SOL_SOCKET, syscall.SO_ERROR)
    96  		}
    97  	default:
    98  		switch network[len(network)-1] {
    99  		case '4':
   100  			fn = func(s uintptr) {
   101  				operr = syscall.SetsockoptInt(int(s), syscall.IPPROTO_IP, syscall.IP_TTL, 1)
   102  			}
   103  		case '6':
   104  			fn = func(s uintptr) {
   105  				operr = syscall.SetsockoptInt(int(s), syscall.IPPROTO_IPV6, syscall.IPV6_UNICAST_HOPS, 1)
   106  			}
   107  		default:
   108  			return errors.New("unknown network: " + network)
   109  		}
   110  	}
   111  	if err := c.Control(fn); err != nil {
   112  		return err
   113  	}
   114  	return operr
   115  }
   116
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