github.com/code-reading/golang@v0.0.0-20220303082512-ba5bc0e589a3/go/src/net/rawconn_unix_test.go (about)

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