557 lines
15 KiB
Groff
557 lines
15 KiB
Groff
.\" Copyright 1998 Juniper Networks, Inc.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD: /repoman/r/ncvs/src/lib/libradius/libradius.3,v 1.17 2004/04/27 15:00:29 ru Exp $
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.\" $NetBSD: libradius.3,v 1.2 2005/12/26 19:40:15 perry Exp $
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.\"
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.Dd April 27, 2004
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.Dt LIBRADIUS 3
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.Os
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.Sh NAME
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.Nm libradius
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.Nd RADIUS client library
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.Sh SYNOPSIS
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.In radlib.h
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.Ft "struct rad_handle *"
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.Fn rad_acct_open "void"
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.Ft int
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.Fn rad_add_server "struct rad_handle *h" "const char *host" "int port" "const char *secret" "int timeout" "int max_tries"
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.Ft "struct rad_handle *"
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.Fn rad_auth_open "void"
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.Ft void
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.Fn rad_close "struct rad_handle *h"
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.Ft int
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.Fn rad_config "struct rad_handle *h" "const char *file"
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.Ft int
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.Fn rad_continue_send_request "struct rad_handle *h" "int selected" "int *fd" "struct timeval *tv"
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.Ft int
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.Fn rad_create_request "struct rad_handle *h" "int code"
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.Ft "struct in_addr"
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.Fn rad_cvt_addr "const void *data"
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.Ft uint32_t
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.Fn rad_cvt_int "const void *data"
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.Ft char *
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.Fn rad_cvt_string "const void *data" "size_t len"
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.Ft int
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.Fn rad_get_attr "struct rad_handle *h" "const void **data" "size_t *len"
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.Ft int
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.Fn rad_get_vendor_attr "uint32_t *vendor" "const void **data" "size_t *len"
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.Ft int
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.Fn rad_init_send_request "struct rad_handle *h" "int *fd" "struct timeval *tv"
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.Ft int
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.Fn rad_put_addr "struct rad_handle *h" "int type" "struct in_addr addr"
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.Ft int
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.Fn rad_put_attr "struct rad_handle *h" "int type" "const void *data" "size_t len"
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.Ft int
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.Fn rad_put_int "struct rad_handle *h" "int type" "uint32_t value"
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.Ft int
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.Fn rad_put_string "struct rad_handle *h" "int type" "const char *str"
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.Ft int
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.Fn rad_put_message_authentic "struct rad_handle *h"
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.Ft int
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.Fn rad_put_vendor_addr "struct rad_handle *h" "int vendor" "int type" "struct in_addr addr"
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.Ft int
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.Fn rad_put_vendor_attr "struct rad_handle *h" "int vendor" "int type" "const void *data" "size_t len"
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.Ft int
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.Fn rad_put_vendor_int "struct rad_handle *h" "int vendor" "int type" "uint32_t value"
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.Ft int
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.Fn rad_put_vendor_string "struct rad_handle *h" "int vendor" "int type" "const char *str"
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.Ft ssize_t
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.Fn rad_request_authenticator "struct rad_handle *h" "char *buf" "size_t len"
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.Ft int
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.Fn rad_send_request "struct rad_handle *h"
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.Ft "const char *"
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.Fn rad_server_secret "struct rad_handle *h"
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.Ft u_char *
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.Fn rad_demangle "struct rad_handle *h" "const void *mangled" "size_t mlen"
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.Ft u_char *
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.Fn rad_demangle_mppe_key "struct rad_handle *h" "const void *mangled" "size_t mlen" "size_t *len"
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.Ft "const char *"
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.Fn rad_strerror "struct rad_handle *h"
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.Sh DESCRIPTION
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The
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.Nm
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library implements the client side of the Remote Authentication Dial
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In User Service (RADIUS).
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RADIUS, defined in RFCs 2865 and 2866,
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allows clients to perform authentication and accounting by means of
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network requests to remote servers.
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.Ss Initialization
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To use the library, an application must first call
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.Fn rad_auth_open
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or
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.Fn rad_acct_open
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to obtain a
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.Vt "struct rad_handle *" ,
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which provides the context for subsequent operations.
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The former function is used for RADIUS authentication and the
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latter is used for RADIUS accounting.
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Calls to
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.Fn rad_auth_open
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and
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.Fn rad_acct_open
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always succeed unless insufficient virtual memory is available.
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If
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the necessary memory cannot be allocated, the functions return
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.Dv NULL .
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For compatibility with earlier versions of this library,
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.Fn rad_open
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is provided as a synonym for
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.Fn rad_auth_open .
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.Pp
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Before issuing any RADIUS requests, the library must be made aware
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of the servers it can contact.
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The easiest way to configure the
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library is to call
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.Fn rad_config .
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.Fn rad_config
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causes the library to read a configuration file whose format is
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described in
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.Xr radius.conf 5 .
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The pathname of the configuration file is passed as the
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.Fa file
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argument to
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.Fn rad_config .
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This argument may also be given as
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.Dv NULL ,
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in which case the standard configuration file
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.Pa /etc/radius.conf
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is used.
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.Fn rad_config
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returns 0 on success, or \-1 if an error occurs.
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.Pp
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The library can also be configured programmatically by calls to
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.Fn rad_add_server .
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The
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.Fa host
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parameter specifies the server host, either as a fully qualified
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domain name or as a dotted-quad IP address in text form.
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The
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.Fa port
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parameter specifies the UDP port to contact on the server.
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If
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.Fa port
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is given as 0, the library looks up the
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.Ql radius/udp
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or
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.Ql radacct/udp
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service in the network
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.Xr services 5
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database, and uses the port found
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there.
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If no entry is found, the library uses the standard RADIUS
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ports, 1812 for authentication and 1813 for accounting.
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The shared secret for the server host is passed to the
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.Fa secret
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parameter.
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It may be any
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.Dv NUL Ns -terminated
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string of bytes.
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The RADIUS protocol
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ignores all but the leading 128 bytes of the shared secret.
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The timeout for receiving replies from the server is passed to the
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.Fa timeout
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parameter, in units of seconds.
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The maximum number of repeated
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requests to make before giving up is passed into the
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.Fa max_tries
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parameter.
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.Fn rad_add_server
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returns 0 on success, or \-1 if an error occurs.
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.Pp
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.Fn rad_add_server
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may be called multiple times, and it may be used together with
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.Fn rad_config .
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At most 10 servers may be specified.
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When multiple servers are given, they are tried in round-robin
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fashion until a valid response is received, or until each server's
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.Fa max_tries
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limit has been reached.
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.Ss Creating a RADIUS Request
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A RADIUS request consists of a code specifying the kind of request,
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and zero or more attributes which provide additional information.
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To
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begin constructing a new request, call
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.Fn rad_create_request .
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In addition to the usual
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.Vt "struct rad_handle *" ,
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this function takes a
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.Fa code
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parameter which specifies the type of the request.
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Most often this
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will be
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.Dv RAD_ACCESS_REQUEST .
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.Fn rad_create_request
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returns 0 on success, or \-1 on if an error occurs.
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.Pp
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After the request has been created with
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.Fn rad_create_request ,
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attributes can be attached to it.
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This is done through calls to
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.Fn rad_put_addr ,
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.Fn rad_put_int ,
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and
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.Fn rad_put_string .
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Each accepts a
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.Fa type
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parameter identifying the attribute, and a value which may be
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an Internet address, an integer, or a
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.Dv NUL Ns -terminated
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string,
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respectively.
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Alternatively,
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.Fn rad_put_vendor_addr ,
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.Fn rad_put_vendor_int
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or
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.Fn rad_put_vendor_string
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may be used to specify vendor specific attributes.
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Vendor specific
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definitions may be found in
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.In radlib_vs.h
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.Pp
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The library also provides a function
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.Fn rad_put_attr
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which can be used to supply a raw, uninterpreted attribute.
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The
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.Fa data
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argument points to an array of bytes, and the
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.Fa len
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argument specifies its length.
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.Pp
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It is possible adding the Message-Authenticator to the request.
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This is an HMAC-MD5 hash of the entire Access-Request packet (see RFC 3579).
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This attribute must be present in any packet that includes an EAP-Message
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attribute.
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It can be added by using the
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.Fn rad_put_message_authentic
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function.
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The
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.Nm
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library
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calculates the HMAC-MD5 hash implicitly before sending the request.
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If the Message-Authenticator was found inside the response packet,
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then the packet is silently dropped, if the validation failed.
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In order to get this feature, the library should be compiled with
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OpenSSL support.
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.Pp
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The
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.Fn rad_put_X
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functions return 0 on success, or \-1 if an error occurs.
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.Ss Sending the Request and Receiving the Response
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After the RADIUS request has been constructed, it is sent either by means of
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.Fn rad_send_request
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or by a combination of calls to
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.Fn rad_init_send_request
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and
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.Fn rad_continue_send_request .
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.Pp
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The
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.Fn rad_send_request
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function sends the request and waits for a valid reply,
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retrying the defined servers in round-robin fashion as necessary.
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If a valid response is received,
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.Fn rad_send_request
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returns the RADIUS code which specifies the type of the response.
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This will typically be
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.Dv RAD_ACCESS_ACCEPT ,
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.Dv RAD_ACCESS_REJECT ,
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or
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.Dv RAD_ACCESS_CHALLENGE .
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If no valid response is received,
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.Fn rad_send_request
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returns \-1.
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.Pp
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As an alternative, if you do not wish to block waiting for a response,
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.Fn rad_init_send_request
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and
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.Fn rad_continue_send_request
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may be used instead.
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If a reply is received from the RADIUS server or a
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timeout occurs, these functions return a value as described for
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.Fn rad_send_request .
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Otherwise, a value of zero is returned and the values pointed to by
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.Fa fd
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and
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.Fa tv
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are set to the descriptor and timeout that should be passed to
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.Xr select 2 .
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.Pp
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.Fn rad_init_send_request
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must be called first, followed by repeated calls to
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.Fn rad_continue_send_request
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as long as a return value of zero is given.
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Between each call, the application should call
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.Xr select 2 ,
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passing
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.Fa *fd
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as a read descriptor and timing out after the interval specified by
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.Fa tv .
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When
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.Xr select 2
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returns,
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.Fn rad_continue_send_request
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should be called with
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.Fa selected
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set to a non-zero value if
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.Xr select 2
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indicated that the descriptor is readable.
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.Pp
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Like RADIUS requests, each response may contain zero or more
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attributes.
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After a response has been received successfully by
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.Fn rad_send_request
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or
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.Fn rad_continue_send_request ,
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its attributes can be extracted one by one using
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.Fn rad_get_attr .
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Each time
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.Fn rad_get_attr
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is called, it gets the next attribute from the current response, and
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stores a pointer to the data and the length of the data via the
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reference parameters
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.Fa data
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and
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.Fa len ,
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respectively.
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Note that the data resides in the response itself,
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and must not be modified.
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A successful call to
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.Fn rad_get_attr
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returns the RADIUS attribute type.
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If no more attributes remain in the current response,
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.Fn rad_get_attr
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returns 0.
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If an error such as a malformed attribute is detected, \-1 is
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returned.
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.Pp
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If
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.Fn rad_get_attr
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returns
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.Dv RAD_VENDOR_SPECIFIC ,
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.Fn rad_get_vendor_attr
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may be called to determine the vendor.
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The vendor specific RADIUS attribute type is returned.
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The reference parameters
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.Fa data
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and
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.Fa len
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(as returned from
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.Fn rad_get_attr )
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are passed to
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.Fn rad_get_vendor_attr ,
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and are adjusted to point to the vendor specific attribute data.
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.Pp
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The common types of attributes can be decoded using
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.Fn rad_cvt_addr ,
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.Fn rad_cvt_int ,
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and
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.Fn rad_cvt_string .
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These functions accept a pointer to the attribute data, which should
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have been obtained using
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.Fn rad_get_attr
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and optionally
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.Fn rad_get_vendor_attr .
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In the case of
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.Fn rad_cvt_string ,
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the length
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.Fa len
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must also be given.
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These functions interpret the attribute as an
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Internet address, an integer, or a string, respectively, and return
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its value.
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.Fn rad_cvt_string
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returns its value as a
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.Dv NUL Ns -terminated
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string in dynamically
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allocated memory.
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The application should free the string using
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.Xr free 3
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when it is no longer needed.
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.Pp
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If insufficient virtual memory is available,
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.Fn rad_cvt_string
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returns
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.Dv NULL .
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.Fn rad_cvt_addr
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and
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.Fn rad_cvt_int
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cannot fail.
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.Pp
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The
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.Fn rad_request_authenticator
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function may be used to obtain the Request-Authenticator attribute value
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associated with the current RADIUS server according to the supplied
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rad_handle.
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The target buffer
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.Fa buf
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of length
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.Fa len
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must be supplied and should be at least 16 bytes.
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The return value is the number of bytes written to
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.Fa buf
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or \-1 to indicate that
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.Fa len
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was not large enough.
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.Pp
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The
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.Fn rad_server_secret
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returns the secret shared with the current RADIUS server according to the
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supplied rad_handle.
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.Pp
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The
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.Fn rad_demangle
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function demangles attributes containing passwords and MS-CHAPv1 MPPE-Keys.
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The return value is
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.Dv NULL
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on failure, or the plaintext attribute.
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This value should be freed using
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.Xr free 3
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when it is no longer needed.
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.Pp
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The
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.Fn rad_demangle_mppe_key
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function demangles the send- and recv-keys when using MPPE (see RFC 2548).
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The return value is
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.Dv NULL
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on failure, or the plaintext attribute.
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This value should be freed using
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.Xr free 3
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when it is no longer needed.
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.Ss Obtaining Error Messages
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Those functions which accept a
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.Vt "struct rad_handle *"
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argument record an error message if they fail.
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The error message
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can be retrieved by calling
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.Fn rad_strerror .
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The message text is overwritten on each new error for the given
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.Vt "struct rad_handle *" .
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Thus the message must be copied if it is to be preserved through
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subsequent library calls using the same handle.
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.Ss Cleanup
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To free the resources used by the RADIUS library, call
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.Fn rad_close .
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.Sh RETURN VALUES
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The following functions return a non-negative value on success.
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If
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they detect an error, they return \-1 and record an error message
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which can be retrieved using
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.Fn rad_strerror .
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.Pp
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.Bl -item -offset indent -compact
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.It
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.Fn rad_add_server
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.It
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.Fn rad_config
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.It
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.Fn rad_create_request
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.It
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.Fn rad_get_attr
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.It
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.Fn rad_put_addr
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.It
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.Fn rad_put_attr
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.It
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.Fn rad_put_int
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.It
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.Fn rad_put_string
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.It
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.Fn rad_put_message_authentic
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.It
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.Fn rad_init_send_request
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.It
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.Fn rad_continue_send_request
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.It
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.Fn rad_send_request
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.El
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.Pp
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The following functions return a
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.No non- Ns Dv NULL
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pointer on success.
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If they are unable to allocate sufficient
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virtual memory, they return
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.Dv NULL ,
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without recording an error message.
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.Pp
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.Bl -item -offset indent -compact
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.It
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.Fn rad_acct_open
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.It
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.Fn rad_auth_open
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.It
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.Fn rad_cvt_string
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.El
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.Pp
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The following functions return a
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.No non- Ns Dv NULL
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pointer on success.
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If they fail, they return
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.Dv NULL ,
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with recording an error message.
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.Pp
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.Bl -item -offset indent -compact
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.It
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.Fn rad_demangle
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.It
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.Fn rad_demangle_mppe_key
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.El
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.Sh FILES
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.Bl -tag -width indent
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.It Pa /etc/radius.conf
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.El
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.Sh SEE ALSO
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.Xr radius.conf 5
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.Rs
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.%A "C. Rigney, et al"
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.%T "Remote Authentication Dial In User Service (RADIUS)"
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.%O "RFC 2865"
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.Re
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.Rs
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.%A "C. Rigney"
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.%T "RADIUS Accounting"
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.%O "RFC 2866"
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.Re
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.Rs
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.%A G. Zorn
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.%T "Microsoft Vendor-specific RADIUS attributes"
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.%O RFC 2548
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.Re
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.Rs
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.%A C. Rigney, et al
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.%T "RADIUS extensions"
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.%O RFC 2869
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.Re
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.Sh AUTHORS
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.An -nosplit
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This software was originally written by
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.An John Polstra ,
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and donated to the
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.Fx
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project by Juniper Networks, Inc.
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.An Oleg Semyonov
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subsequently added the ability to perform RADIUS
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accounting.
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Later additions and changes by
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.An Michael Bretterklieber .
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