.\" @(#)bindresvport.3n	2.2 88/08/02 4.0 RPCSRC; from 1.7 88/03/14 SMI

.\"

.Dd November 22, 1987

.Dt BINDRESVPORT 3

.Os

.Sh NAME

.Nm bindresvport ,

.Nm bindresvport_sa

.Nd bind a socket to a privileged IP port

.Sh SYNOPSIS

.In sys/types.h

.In rpc/rpc.h

.Ft int

.Fn bindresvport "int sd" "struct sockaddr_in *sin"

.Ft int

.Fn bindresvport_sa "int sd" "struct sockaddr *sa"

.Sh DESCRIPTION

The

.Fn bindresvport

and

.Fn bindresvport_sa

functions

are used to bind a socket descriptor to a privileged

.Tn IP

port, that is, a

port number in the range 0-1023.

.Pp

If

.Fa sin

is a pointer to a

.Ft "struct sockaddr_in"

then the appropriate fields in the structure should be defined.

Note that

.Fa sin->sin_family

must be initialized to the address family of the socket, passed by

.Fa sd .

If

.Fa sin->sin_port

is

.Sq 0

then an anonymous port (in the range 600-1023) will be

chosen, and if

.Xr bind 2

is successful, the

.Fa sin->sin_port

will be updated to contain the allocated port.

.Pp

If

.Fa sin

is the

.Dv NULL

pointer,

an anonymous port will be allocated (as above).

However, there is no way for

.Fn bindresvport

to return the allocated port in this case.

.Pp

Only root can bind to a privileged port; this call will fail for any

other users.

.Pp

Function prototype of

.Fn bindresvport

is biased to

.Dv AF_INET

socket.

The

.Fn bindresvport_sa

function

acts exactly the same, with more neutral function prototype.

Note that both functions behave exactly the same, and

both support

.Dv AF_INET6

sockets as well as

.Dv AF_INET

sockets.

.Sh RETURN VALUES

.Rv -std bindresvport

.Sh ERRORS

.Bl -tag -width Er

.It Bq Er EPFNOSUPPORT

If second argument was supplied,

and address family did not match between arguments.

.El

.Pp

The

.Fn bindresvport

function

may also fail and set

.Va errno

for any of the errors specified for the calls

.Xr bind 2 ,

.Xr getsockopt 2 ,

or

.Xr setsockopt 2 .

.Sh AVAILABILITY

The

.Fn bindresvport

function is part of libtirpc.

.Sh SEE ALSO

.Xr bind 2 ,

.Xr getsockopt 2 ,

.Xr setsockopt 2