gen/FreeBSD/getpeereid.3

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  26 .\" $FreeBSD: src/lib/libc/gen/getpeereid.3,v 1.6 2002/12/18 10:13:54 ru Exp $
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  28 .Dd July 15, 2001
  29 .Dt GETPEEREID 3
  30 .Os
  31 .Sh NAME
  32 .Nm getpeereid
  33 .Nd get the effective credentials of a UNIX-domain peer
  34 .Sh LIBRARY
  35 .Lb libc
  36 .Sh SYNOPSIS
  37 .In sys/types.h
  38 .In unistd.h
  39 .Ft int
  40 .Fn getpeereid "int s" "uid_t *euid" "gid_t *egid"
  41 .Sh DESCRIPTION
  42 The
  43 .Fn getpeereid
  44 function returns the effective user and group IDs of the
  45 peer connected to a
  46 .Ux Ns -domain
  47 socket.
  48 The argument
  49 .Fa s
  50 must be a
  51 .Ux Ns -domain
  52 socket
  53 .Pq Xr unix 4
  54 of type
  55 .Dv SOCK_STREAM
  56 on which either
  57 .Xr connect 2
  58 or
  59 .Xr listen 2
  60 have been called.
  61 The effective used ID is placed in
  62 .Fa euid ,
  63 and the effective group ID in
  64 .Fa egid .
  65 .Pp
  66 The credentials returned to the
  67 .Xr listen 2
  68 caller are those of its peer at the time it called
  69 .Xr connect 2 ;
  70 the credentials returned to the
  71 .Xr connect 2
  72 caller are those of its peer at the time it called
  73 .Xr listen 2 .
  74 This mechanism is reliable; there is no way for either side to influence
  75 the credentials returned to its peer except by calling the appropriate
  76 system call (i.e., either
  77 .Xr connect 2
  78 or
  79 .Xr listen 2 )
  80 under different effective credentials.
  81 .Pp
  82 One common use of this routine is for a
  83 .Ux Ns -domain
  84 server
  85 to verify the credentials of its client.
  86 Likewise, the client can verify the credentials of the server.
  87 .Sh IMPLEMENTATION NOTES
  88 On
  89 .Fx ,
  90 .Fn getpeereid
  91 is implemented in terms of the
  92 .Dv LOCAL_PEERCRED
  93 .Xr unix 4
  94 socket option.
  95 .Sh RETURN VALUES
  96 .Rv -std getpeereid
  97 .Sh ERRORS
  98 The
  99 .Fn getpeereid
 100 function
 101 fails if:
 102 .Bl -tag -width Er
 103 .It Bq Er EBADF
 104 The argument
 105 .Fa s
 106 is not a valid descriptor.
 107 .It Bq Er ENOTSOCK
 108 The argument
 109 .Fa s
 110 is a file, not a socket.
 111 .It Bq Er ENOTCONN
 112 The argument
 113 .Fa s
 114 does not refer to a socket on which
 115 .Xr connect 2
 116 or
 117 .Xr listen 2
 118 have been called.
 119 .It Bq Er EINVAL
 120 The argument
 121 .Fa s
 122 does not refer to a socket of type
 123 .Dv SOCK_STREAM ,
 124 or the kernel returned invalid data.
 125 .El
 126 .Sh SEE ALSO
 127 .Xr connect 2 ,
 128 .Xr getpeername 2 ,
 129 .Xr getsockname 2 ,
 130 .Xr getsockopt 2 ,
 131 .Xr listen 2 ,
 132 .Xr unix 4
 133 .Sh HISTORY
 134 The
 135 .Fn getpeereid
 136 function appeared in
 137 .Fx 4.6 .