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LIBRADIUS(3)		 BSD Library Functions Manual		  LIBRADIUS(3)

     libradius -- RADIUS client/server library

     #include <radlib.h>

     struct rad_handle *

     rad_add_server(struct rad_handle *h, const	char *host, int	port,
	 const char *secret, int timeout, int max_tries);

     struct rad_handle *

     rad_close(struct rad_handle *h);

     rad_config(struct rad_handle *h, const char *file);

     rad_continue_send_request(struct rad_handle *h, int selected, int *fd,
	 struct	timeval	*tv);

     rad_create_request(struct rad_handle *h, int code);

     rad_create_response(struct	rad_handle *h, int code);

     struct in_addr
     rad_cvt_addr(const	void *data);

     rad_cvt_int(const void *data);

     char *
     rad_cvt_string(const void *data, size_t len);

     rad_get_attr(struct rad_handle *h,	const void **data, size_t *len);

     rad_get_vendor_attr(u_int32_t *vendor, const void **data, size_t *len);

     rad_init_send_request(struct rad_handle *h, int *fd, struct timeval *tv);

     rad_put_addr(struct rad_handle *h,	int type, struct in_addr addr);

     rad_put_attr(struct rad_handle *h,	int type, const	void *data,
	 size_t	len);

     rad_put_int(struct	rad_handle *h, int type, u_int32_t value);

     rad_put_string(struct rad_handle *h, int type, const char *str);

     rad_put_message_authentic(struct rad_handle *h);

     rad_put_vendor_addr(struct	rad_handle *h, int vendor, int type,
	 struct	in_addr	addr);

     rad_put_vendor_attr(struct	rad_handle *h, int vendor, int type,
	 const void *data, size_t len);

     rad_put_vendor_int(struct rad_handle *h, int vendor, int type,
	 u_int32_t value);

     rad_put_vendor_string(struct rad_handle *h, int vendor, int type,
	 const char *str);

     rad_request_authenticator(struct rad_handle *h, char *buf,	size_t len);

     rad_receive_request(struct	rad_handle *h);

     rad_send_request(struct rad_handle	*h);

     rad_send_response(struct rad_handle *h);

     struct rad_handle *
     rad_server_open(int fd);

     const char	*
     rad_server_secret(struct rad_handle *h);

     rad_bind_to(struct	rad_handle *h, in_addr_t addr);

     u_char *
     rad_demangle(struct rad_handle *h,	const void *mangled, size_t mlen);

     u_char *
     rad_demangle_mppe_key(struct rad_handle *h, const void *mangled,
	 size_t	mlen, size_t *len);

     const char	*
     rad_strerror(struct rad_handle *h);

     The libradius library implements the Remote Authentication	Dial In	User
     Service (RADIUS).	RADIUS,	defined	in RFCs	2865 and 2866, allows clients
     to	perform	authentication and accounting by means of network requests to
     remote servers.

     To	use the	library, an application	must first call	rad_auth_open(),
     rad_acct_open() or	rad_server_open() to obtain a struct rad_handle	*,
     which provides the	context	for subsequent operations.  The	former func-
     tion is used for RADIUS authentication and	the latter is used for RADIUS
     accounting.  Calls	to rad_auth_open(), rad_acct_open() and
     rad_server_open() always succeed unless insufficient virtual memory is
     available.	 If the	necessary memory cannot	be allocated, the functions
     return NULL.  For compatibility with earlier versions of this library,
     rad_open()	is provided as a synonym for rad_auth_open().

     Before issuing any	RADIUS requests, the library must be made aware	of the
     servers it	can contact.  The easiest way to configure the library is to
     call rad_config().	 rad_config() causes the library to read a configura-
     tion file whose format is described in radius.conf(5).  The pathname of
     the configuration file is passed as the file argument to rad_config().
     This argument may also be given as	NULL, in which case the	standard con-
     figuration	file /etc/radius.conf is used.	rad_config() returns 0 on suc-
     cess, or -1 if an error occurs.

     The library can also be configured	programmatically by calls to
     rad_add_server().	The host parameter specifies the server	host, either
     as	a fully	qualified domain name or as a dotted-quad IP address in	text
     form.  The	port parameter specifies the UDP port to contact on the
     server.  If port is given as 0, the library looks up the `radius/udp' or
     `radacct/udp' service in the network services(5) database,	and uses the
     port found	there.	If no entry is found, the library uses the standard
     RADIUS ports, 1812	for authentication and 1813 for	accounting.  The
     shared secret for the server host is passed to the	secret parameter.  It
     may be any	NUL-terminated string of bytes.	 The RADIUS protocol ignores
     all but the leading 128 bytes of the shared secret.  The timeout for re-
     ceiving replies from the server is	passed to the timeout parameter, in
     units of seconds.	The maximum number of repeated requests	to make	before
     giving up is passed into the max_tries parameter.	rad_add_server() re-
     turns 0 on	success, or -1 if an error occurs.

     rad_add_server() may be called multiple times, and	it may be used to-
     gether with rad_config().	At most	10 servers may be specified.  When
     multiple servers are given, they are tried	in round-robin fashion until a
     valid response is received, or until each server's	max_tries limit	has
     been reached.

   Creating a RADIUS Request
     A RADIUS request consists of a code specifying the	kind of	request, and
     zero or more attributes which provide additional information.  To begin
     constructing a new	request, call rad_create_request().  In	addition to
     the usual struct rad_handle *, this function takes	a code parameter which
     specifies the type	of the request.	 Most often this will be
     RAD_ACCESS_REQUEST.  rad_create_request() returns 0 on success, or	-1 on
     if	an error occurs.

     After the request has been	created	with rad_create_request(), attributes
     can be attached to	it.  This is done through calls	to rad_put_addr(),
     rad_put_int(), and	rad_put_string().  Each	accepts	a type parameter iden-
     tifying the attribute, and	a value	which may be an	Internet address, an
     integer, or a NUL-terminated string, respectively.	 Alternatively,
     rad_put_vendor_addr(), rad_put_vendor_int() or rad_put_vendor_string()
     may be used to specify vendor specific attributes.	 Vendor	specific defi-
     nitions may be found in <radlib_vs.h>

     The library also provides a function rad_put_attr() which can be used to
     supply a raw, uninterpreted attribute.  The data argument points to an
     array of bytes, and the len argument specifies its	length.

     It	is possible adding the Message-Authenticator to	the request.  This is
     an	HMAC-MD5 hash of the entire Access-Request packet (see RFC 3579).
     This attribute must be present in any packet that includes	an EAP-Message
     attribute.	 It can	be added by using the rad_put_message_authentic()
     function.	The libradius library calculates the HMAC-MD5 hash implicitly
     before sending the	request.  If the Message-Authenticator was found in-
     side the response packet, then the	packet is silently dropped, if the
     validation	failed.	 In order to get this feature, the library should be
     compiled with OpenSSL support.

     The rad_put_X() functions return 0	on success, or -1 if an	error occurs.

   Sending the Request and Receiving the Response
     After the RADIUS request has been constructed, it is sent either by means
     of	rad_send_request() or by a combination of calls	to
     rad_init_send_request() and rad_continue_send_request().

     The rad_send_request() function sends the request and waits for a valid
     reply, retrying the defined servers in round-robin	fashion	as necessary.
     If	a valid	response is received, rad_send_request() returns the RADIUS
     code which	specifies the type of the response.  This will typically be
     valid response is received, rad_send_request() returns -1.

     As	an alternative,	if you do not wish to block waiting for	a response,
     rad_init_send_request() and rad_continue_send_request() may be used in-
     stead.  If	a reply	is received from the RADIUS server or a	timeout	oc-
     curs, these functions return a value as described for rad_send_request().
     Otherwise,	a value	of zero	is returned and	the values pointed to by fd
     and tv are	set to the descriptor and timeout that should be passed	to

     rad_init_send_request() must be called first, followed by repeated	calls
     to	rad_continue_send_request() as long as a return	value of zero is
     given.  Between each call,	the application	should call select(2), passing
     *fd as a read descriptor and timing out after the interval	specified by
     tv.  When select(2) returns, rad_continue_send_request() should be	called
     with selected set to a non-zero value if select(2)	indicated that the de-
     scriptor is readable.

     Like RADIUS requests, each	response may contain zero or more attributes.
     After a response has been received	successfully by	rad_send_request() or
     rad_continue_send_request(), its attributes can be	extracted one by one
     using rad_get_attr().  Each time rad_get_attr() is	called,	it gets	the
     next attribute from the current response, and stores a pointer to the
     data and the length of the	data via the reference parameters data and
     len, respectively.	 Note that the data resides in the response itself,
     and must not be modified.	A successful call to rad_get_attr() returns
     the RADIUS	attribute type.	 If no more attributes remain in the current
     response, rad_get_attr() returns 0.  If an	error such as a	malformed at-
     tribute is	detected, -1 is	returned.

     If	rad_get_attr() returns RAD_VENDOR_SPECIFIC, rad_get_vendor_attr() may
     be	called to determine the	vendor.	 The vendor specific RADIUS attribute
     type is returned.	The reference parameters data and len (as returned
     from rad_get_attr()) are passed to	rad_get_vendor_attr(), and are ad-
     justed to point to	the vendor specific attribute data.

     The common	types of attributes can	be decoded using rad_cvt_addr(),
     rad_cvt_int(), and	rad_cvt_string().  These functions accept a pointer to
     the attribute data, which should have been	obtained using rad_get_attr()
     and optionally rad_get_vendor_attr().  In the case	of rad_cvt_string(),
     the length	len must also be given.	 These functions interpret the attri-
     bute as an	Internet address, an integer, or a string, respectively, and
     return its	value.	rad_cvt_string() returns its value as a	NUL-terminated
     string in dynamically allocated memory.  The application should free the
     string using free(3) when it is no	longer needed.

     If	insufficient virtual memory is available, rad_cvt_string() returns
     NULL.  rad_cvt_addr() and rad_cvt_int() cannot fail.

     The rad_request_authenticator() function may be used to obtain the	Re-
     quest-Authenticator attribute value associated with the current RADIUS
     server according to the supplied rad_handle.  The target buffer buf of
     length len	must be	supplied and should be at least	16 bytes.  The return
     value is the number of bytes written to buf or -1 to indicate that	len
     was not large enough.

     The rad_server_secret() returns the secret	shared with the	current	RADIUS
     server according to the supplied rad_handle.

     The rad_bind_to() assigns a source	address	for all	requests to the	cur-
     rent RADIUS server.

     The rad_demangle()	function demangles attributes containing passwords and
     MS-CHAPv1 MPPE-Keys.  The return value is NULL on failure,	or the plain-
     text attribute.  This value should	be freed using free(3) when it is no
     longer needed.

     The rad_demangle_mppe_key() function demangles the	send- and recv-keys
     when using	MPPE (see RFC 2548).  The return value is NULL on failure, or
     the plaintext attribute.  This value should be freed using	free(3)	when
     it	is no longer needed.

   Obtaining Error Messages
     Those functions which accept a struct rad_handle *	argument record	an er-
     ror message if they fail.	The error message can be retrieved by calling
     rad_strerror().  The message text is overwritten on each new error	for
     the given struct rad_handle *.  Thus the message must be copied if	it is
     to	be preserved through subsequent	library	calls using the	same handle.

     To	free the resources used	by the RADIUS library, call rad_close().

   Server operation
     Server mode operates much alike to	client mode, except packet send	and
     receieve steps are	swapped. To operate as server you should obtain	server
     context with rad_server_open() function, passing opened and bound UDP
     socket file descriptor as argument.  You should define allowed clients
     and their secrets using rad_add_server() function.	port, timeout and
     max_tries arguments are ignored in	server mode.  You should call
     rad_receive_request() function to receive request from client. If you do
     not want to block on socket read, you are free to use any poll(), se-
     lect() or non-blocking sockets for	the socket.  Received request can be
     parsed with same parsing functions	as for client.	To respond to the re-
     quest you should call rad_create_response() and fill response content
     with same packet writing functions	as for client.	When packet is ready,
     it	should be sent with rad_send_response().

     The following functions return a non-negative value on success.  If they
     detect an error, they return -1 and record	an error message which can be
     retrieved using rad_strerror().


     The following functions return a non-NULL pointer on success.  If they
     are unable	to allocate sufficient virtual memory, they return NULL, with-
     out recording an error message.


     The following functions return a non-NULL pointer on success.  If they
     fail, they	return NULL, with recording an error message.




     C.	Rigney,	et al, Remote Authentication Dial In User Service (RADIUS),
     RFC 2865.

     C.	Rigney,	RADIUS Accounting, RFC 2866.

     G.	Zorn, Microsoft	Vendor-specific	RADIUS attributes, RFC 2548.

     C.	Rigney,	et al, RADIUS extensions, RFC 2869.

     This software was originally written by John Polstra, and donated to the
     FreeBSD project by	Juniper	Networks, Inc.	Oleg Semyonov subsequently
     added the ability to perform RADIUS accounting.  Later additions and
     changes by	Michael	Bretterklieber.	 Server	mode support was added by
     Alexander Motin.

BSD				August 5, 2009				   BSD


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