libgo/go/syscall/sockcmsg_linux.go

   1 // Copyright 2011 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 // Socket control messages
   6
   7 package syscall
   8
   9 import "unsafe"
  10
  11 // UnixCredentials encodes credentials into a socket control message
  12 // for sending to another process. This can be used for
  13 // authentication.
  14 func UnixCredentials(ucred *Ucred) []byte {
  15         b := make([]byte, CmsgSpace(SizeofUcred))
  16         h := (*Cmsghdr)(unsafe.Pointer(&b[0]))
  17         h.Level = SOL_SOCKET
  18         h.Type = SCM_CREDENTIALS
  19         h.SetLen(CmsgLen(SizeofUcred))
  20         *((*Ucred)(cmsgData(h))) = *ucred
  21         return b
  22 }
  23
  24 // ParseUnixCredentials decodes a socket control message that contains
  25 // credentials in a Ucred structure. To receive such a message, the
  26 // SO_PASSCRED option must be enabled on the socket.
  27 func ParseUnixCredentials(m *SocketControlMessage) (*Ucred, error) {
  28         if m.Header.Level != SOL_SOCKET {
  29                 return nil, EINVAL
  30         }
  31         if m.Header.Type != SCM_CREDENTIALS {
  32                 return nil, EINVAL
  33         }
  34         if uintptr(len(m.Data)) < unsafe.Sizeof(Ucred{}) {
  35                 return nil, EINVAL
  36         }
  37         ucred := *(*Ucred)(unsafe.Pointer(&m.Data[0]))
  38         return &ucred, nil
  39 }