sys_freebsd.go

     1  // Copyright 2016 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  package routebsd
     6  
     7  import (
     8  	"syscall"
     9  	"unsafe"
    10  )
    11  
    12  // MTU returns the interface MTU.
    13  func (m *InterfaceMessage) MTU() int {
    14  	return int(nativeEndian.Uint32(m.raw[m.extOff+8 : m.extOff+12]))
    15  }
    16  
    17  // sizeofIfMsghdr is the size used on FreeBSD 11 for all platforms.
    18  const sizeofIfMsghdr = 0xa8
    19  
    20  func probeRoutingStack() (int, map[int]*wireFormat) {
    21  	var p uintptr
    22  	wordSize := int(unsafe.Sizeof(p))
    23  	align := wordSize
    24  	// In the case of kern.supported_archs="amd64 i386", we need
    25  	// to know the underlying kernel's architecture because the
    26  	// alignment for routing facilities are set at the build time
    27  	// of the kernel.
    28  	conf, _ := syscall.Sysctl("kern.conftxt")
    29  	for i, j := 0, 0; j < len(conf); j++ {
    30  		if conf[j] != '\n' {
    31  			continue
    32  		}
    33  		s := conf[i:j]
    34  		i = j + 1
    35  		if len(s) > len("machine") && s[:len("machine")] == "machine" {
    36  			s = s[len("machine"):]
    37  			for k := 0; k < len(s); k++ {
    38  				if s[k] == ' ' || s[k] == '\t' {
    39  					s = s[1:]
    40  				}
    41  				break
    42  			}
    43  			if s == "amd64" {
    44  				align = 8
    45  			}
    46  			break
    47  		}
    48  	}
    49  	ifm := &wireFormat{extOff: 16, bodyOff: sizeofIfMsghdr}
    50  	ifm.parse = ifm.parseInterfaceMessage
    51  	ifam := &wireFormat{extOff: syscall.SizeofIfaMsghdr, bodyOff: syscall.SizeofIfaMsghdr}
    52  	ifam.parse = ifam.parseInterfaceAddrMessage
    53  	ifmam := &wireFormat{extOff: syscall.SizeofIfmaMsghdr, bodyOff: syscall.SizeofIfmaMsghdr}
    54  	ifmam.parse = ifmam.parseInterfaceMulticastAddrMessage
    55  	return align, map[int]*wireFormat{
    56  		syscall.RTM_NEWADDR:  ifam,
    57  		syscall.RTM_DELADDR:  ifam,
    58  		syscall.RTM_IFINFO:   ifm,
    59  		syscall.RTM_NEWMADDR: ifmam,
    60  		syscall.RTM_DELMADDR: ifmam,
    61  	}
    62  }
    63
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