1.\" $OpenBSD: getpeereid.3,v 1.4 2022/09/11 06:38:10 jmc Exp $ 2.\" 3.\" Copyright (c) 1983, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. Neither the name of the University nor the names of its contributors 15.\" may be used to endorse or promote products derived from this software 16.\" without specific prior written permission. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28.\" SUCH DAMAGE. 29.Dd $Mdocdate: September 11 2022 $ 30.Dt GETPEEREID 3 31.Os 32.Sh NAME 33.Nm getpeereid 34.Nd get effective user and group identification of locally-connected peer 35.Sh SYNOPSIS 36.In sys/types.h 37.In sys/socket.h 38.Ft int 39.Fn getpeereid "int s" "uid_t *euid" "gid_t *egid" 40.Sh DESCRIPTION 41.Fn getpeereid 42returns the effective user ID and group ID of the peer connected to 43a 44.Ux Ns -domain 45socket (see 46.Xr unix 4 ) . 47The argument 48.Fa s 49must be of type 50.Dv SOCK_STREAM 51or 52.Dv SOCK_SEQPACKET . 53.Pp 54One common use is for 55.Ux Ns -domain 56servers to determine the credentials of clients that have connected to it. 57.Pp 58.Fn getpeereid 59takes three parameters: 60.Bl -bullet 61.It 62.Fa s 63contains the file descriptor of the socket whose peer credentials 64should be looked up. 65.It 66.Fa euid 67points to a 68.Vt uid_t 69variable into which the effective user ID for the connected peer will 70be stored. 71.It 72.Fa egid 73points to a 74.Vt gid_t 75variable into which the effective group ID for the connected peer will 76be stored. 77.El 78.Sh RETURN VALUES 79If the call succeeds, a 0 is returned and 80.Fa euid 81and 82.Fa egid 83are set to the effective user ID and group ID of the connected peer. 84Otherwise, 85.Va errno 86is set and a value of \-1 is returned. 87.Sh ERRORS 88On failure, 89.Va errno 90is set to one of the following: 91.Bl -tag -width Er 92.It Bq Er EBADF 93The argument 94.Fa s 95is not a valid descriptor. 96.It Bq Er ENOTSOCK 97The argument 98.Fa s 99is a file, not a socket. 100.It Bq Er EOPNOTSUPP 101The socket is not in the 102.Ux Ns -domain . 103.It Bq Er ENOTCONN 104The socket is not connected. 105.It Bq Er ENOBUFS 106Insufficient resources were available in the system 107to perform the operation. 108.El 109.Sh SEE ALSO 110.Xr accept 2 , 111.Xr bind 2 , 112.Xr getpeername 2 , 113.Xr getsockname 2 , 114.Xr getsockopt 2 , 115.Xr socket 2 , 116.Xr unix 4 117.Sh HISTORY 118The 119.Fn getpeereid 120function call appeared in 121.Ox 3.0 . 122