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25 .\" $FreeBSD: src/lib/libradius/libradius.3,v 1.6.2.6 2002/11/27 17:36:00 archie Exp $
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28 .Dd October 30, 1999
29 .Dt LIBRADIUS 3
30 .Os
31 .Sh NAME
32 .Nm libradius
33 .Nd RADIUS client library
34 .Sh LIBRARY
35 .Lb libradius
36 .Sh SYNOPSIS
37 .In radlib.h
38 .Ft struct rad_handle *
39 .Fn rad_acct_open "void"
40 .Ft int
41 .Fn rad_add_server "struct rad_handle *h" "const char *host" "int port" "const char *secret" "int timeout" "int max_tries"
42 .Ft struct rad_handle *
43 .Fn rad_auth_open "void"
44 .Ft void
45 .Fn rad_close "struct rad_handle *h"
46 .Ft int
47 .Fn rad_config "struct rad_handle *h" "const char *file"
48 .Ft int
49 .Fn rad_continue_send_request "struct rad_handle *h" "int selected" "int *fd" "struct timeval *tv"
50 .Ft int
51 .Fn rad_create_request "struct rad_handle *h" "int code"
52 .Ft struct in_addr
53 .Fn rad_cvt_addr "const void *data"
54 .Ft u_int32_t
55 .Fn rad_cvt_int "const void *data"
56 .Ft char *
57 .Fn rad_cvt_string "const void *data" "size_t len"
58 .Ft int
59 .Fn rad_get_attr "struct rad_handle *h" "const void **data" "size_t *len"
60 .Ft int
61 .Fn rad_get_vendor_attr "u_int32_t *vendor" "const void **data" "size_t *len"
62 .Ft int
63 .Fn rad_init_send_request "struct rad_handle *h" "int *fd" "struct timeval *tv"
64 .Ft int
65 .Fn rad_put_addr "struct rad_handle *h" "int type" "struct in_addr addr"
66 .Ft int
67 .Fn rad_put_attr "struct rad_handle *h" "int type" "const void *data" "size_t len"
68 .Ft int
69 .Fn rad_put_int "struct rad_handle *h" "int type" "u_int32_t value"
70 .Ft int
71 .Fn rad_put_string "struct rad_handle *h" "int type" "const char *str"
72 .Ft int
73 .Fn rad_put_vendor_addr "struct rad_handle *h" "int vendor" "int type" "struct in_addr addr"
74 .Ft int
75 .Fn rad_put_vendor_attr "struct rad_handle *h" "int vendor" "int type" "const void *data" "size_t len"
76 .Ft int
77 .Fn rad_put_vendor_int "struct rad_handle *h" "int vendor" "int type" "u_int32_t value"
78 .Ft int
79 .Fn rad_put_vendor_string "struct rad_handle *h" "int vendor" "int type" "const char *str"
80 .Ft ssize_t
81 .Fn rad_request_authenticator "struct rad_handle *h" "char *buf" "size_t len"
82 .Ft int
83 .Fn rad_send_request "struct rad_handle *h"
84 .Ft const char *
85 .Fn rad_server_secret "struct rad_handle *h"
86 .Ft const char *
87 .Fn rad_strerror "struct rad_handle *h"
88 .Sh DESCRIPTION
89 The
90 .Nm
91 library implements the client side of the Remote Authentication Dial
92 In User Service (RADIUS). RADIUS, defined in RFCs 2138 and 2139,
93 allows clients to perform authentication and accounting by means of
94 network requests to remote servers.
95 .Sh INITIALIZATION
96 To use the library, an application must first call
97 .Fn rad_auth_open
98 or
99 .Fn rad_acct_open
100 to obtain a
101 .Va struct rad_handle * ,
102 which provides the context for subsequent operations.
103 The former function is used for RADIUS authentication and the
104 latter is used for RADIUS accounting.
105 Calls to
106 .Fn rad_auth_open
107 and
108 .Fn rad_acct_open
109 always succeed unless insufficient virtual memory is available. If
110 the necessary memory cannot be allocated, the functions return
111 .Dv NULL .
112 For compatibility with earlier versions of this library,
113 .Fn rad_open
114 is provided as a synonym for
115 .Fn rad_auth_open .
116 .Pp
117 Before issuing any RADIUS requests, the library must be made aware
118 of the servers it can contact. The easiest way to configure the
119 library is to call
120 .Fn rad_config .
121 .Fn rad_config
122 causes the library to read a configuration file whose format is
123 described in
124 .Xr radius.conf 5 .
125 The pathname of the configuration file is passed as the
126 .Va file
127 argument to
128 .Fn rad_config .
129 This argument may also be given as
130 .Dv NULL ,
131 in which case the standard configuration file
132 .Pa /etc/radius.conf
133 is used.
134 .Fn rad_config
135 returns 0 on success, or -1 if an error occurs.
136 .Pp
137 The library can also be configured programmatically by calls to
138 .Fn rad_add_server .
139 The
140 .Va host
141 parameter specifies the server host, either as a fully qualified
142 domain name or as a dotted-quad IP address in text form.
143 The
144 .Va port
145 parameter specifies the UDP port to contact on the server. If
146 .Va port
147 is given as 0, the library looks up the
148 .Ql radius/udp
149 or
150 .Ql radacct/udp
151 service in the network services database, and uses the port found
152 there. If no entry is found, the library uses the standard RADIUS
153 ports, 1812 for authentication and 1813 for accounting.
154 The shared secret for the server host is passed to the
155 .Va secret
156 parameter.
157 It may be any NUL-terminated string of bytes. The RADIUS protocol
158 ignores all but the leading 128 bytes of the shared secret.
159 The timeout for receiving replies from the server is passed to the
160 .Va timeout
161 parameter, in units of seconds. The maximum number of repeated
162 requests to make before giving up is passed into the
163 .Va max_tries
164 parameter.
165 .Fn rad_add_server
166 returns 0 on success, or -1 if an error occurs.
167 .Pp
168 .Fn rad_add_server
169 may be called multiple times, and it may be used together with
170 .Fn rad_config .
171 At most 10 servers may be specified.
172 When multiple servers are given, they are tried in round-robin
173 fashion until a valid response is received, or until each server's
174 .Va max_tries
175 limit has been reached.
176 .Sh CREATING A RADIUS REQUEST
177 A RADIUS request consists of a code specifying the kind of request,
178 and zero or more attributes which provide additional information. To
179 begin constructing a new request, call
180 .Fn rad_create_request .
181 In addition to the usual
182 .Va struct rad_handle * ,
183 this function takes a
184 .Va code
185 parameter which specifies the type of the request. Most often this
186 will be
187 .Dv RAD_ACCESS_REQUEST .
188 .Fn rad_create_request
189 returns 0 on success, or -1 on if an error occurs.
190 .Pp
191 After the request has been created with
192 .Fn rad_create_request ,
193 attributes can be attached to it. This is done through calls to
194 .Fn rad_put_addr ,
195 .Fn rad_put_int ,
196 and
197 .Fn rad_put_string .
198 Each accepts a
199 .Va type
200 parameter identifying the attribute, and a value which may be
201 an Internet address, an integer, or a NUL-terminated string,
202 respectively.
203 Alternatively,
204 .Fn rad_put_vendor_addr ,
205 .Fn rad_put_vendor_int
206 or
207 .Fn rad_put_vendor_string
208 may be used to specify vendor specific attributes. Vendor specific
209 definitions may be found in
210 .In radlib_vs.h
211 .Pp
212 The library also provides a function
213 .Fn rad_put_attr
214 which can be used to supply a raw, uninterpreted attribute. The
215 .Va data
216 argument points to an array of bytes, and the
217 .Va len
218 argument specifies its length.
219 .Pp
220 The
221 .Fn rad_put_X
222 functions return 0 on success, or -1 if an error occurs.
223 .Sh SENDING THE REQUEST AND RECEIVING THE RESPONSE
224 After the RADIUS request has been constructed, it is sent either by means of
225 .Fn rad_send_request
226 or by a combination of calls to
227 .Fn rad_init_send_request
228 and
229 .Fn rad_continue_send_request .
230 .Pp
231 The
232 .Fn rad_send_request
233 function sends the request and waits for a valid reply,
234 retrying the defined servers in round-robin fashion as necessary.
235 If a valid response is received,
236 .Fn rad_send_request
237 returns the RADIUS code which specifies the type of the response.
238 This will typically be
239 .Dv RAD_ACCESS_ACCEPT ,
240 .Dv RAD_ACCESS_REJECT ,
241 or
242 .Dv RAD_ACCESS_CHALLENGE .
243 If no valid response is received,
244 .Fn rad_send_request
245 returns -1.
246 .Pp
247 As an alternative, if you do not wish to block waiting for a response,
248 .Fn rad_init_send_request
249 and
250 .Fn rad_continue_send_request
251 may be used instead. If a reply is received from the RADIUS server or a
252 timeout occurs, these functions return a value as described for
253 .Fn rad_send_request .
254 Otherwise, a value of zero is returned and the values pointed to by
255 .Ar fd
256 and
257 .Ar tv
258 are set to the descriptor and timeout that should be passed to
259 .Xr select 2 .
260 .Pp
261 .Fn rad_init_send_request
262 must be called first, followed by repeated calls to
263 .Fn rad_continue_send_request
264 as long as a return value of zero is given.
265 Between each call, the application should call
266 .Xr select 2 ,
267 passing
268 .Ar *fd
269 as a read descriptor and timing out after the interval specified by
270 .Ar tv .
271 When select returns,
272 .Fn rad_continue_send_request
273 should be called with
274 .Ar selected
275 set to a non-zero value if
276 .Xr select 2
277 indicated that the descriptor is readable.
278 .Pp
279 Like RADIUS requests, each response may contain zero or more
280 attributes. After a response has been received successfully by
281 .Fn rad_send_request
282 or
283 .Fn rad_continue_send_request ,
284 its attributes can be extracted one by one using
285 .Fn rad_get_attr .
286 Each time
287 .Fn rad_get_attr
288 is called, it gets the next attribute from the current response, and
289 stores a pointer to the data and the length of the data via the
290 reference parameters
291 .Va data
292 and
293 .Va len ,
294 respectively. Note that the data resides in the response itself,
295 and must not be modified.
296 A successful call to
297 .Fn rad_get_attr
298 returns the RADIUS attribute type.
299 If no more attributes remain in the current response,
300 .Fn rad_get_attr
301 returns 0.
302 If an error such as a malformed attribute is detected, -1 is
303 returned.
304 .Pp
305 If
306 .Fn rad_get_attr
307 returns
308 .Dv RAD_VENDOR_SPECIFIC ,
309 .Fn rad_get_vendor_attr
310 may be called to determine the vendor.
311 The vendor specific RADIUS attribute type is returned.
312 The reference parameters
313 .Va data
314 and
315 .Va len
316 .Pq as returned from Fn rad_get_attr
317 are passed to
318 .Fn rad_get_vendor_attr ,
319 and are adjusted to point to the vendor specific attribute data.
320 .Pp
321 The common types of attributes can be decoded using
322 .Fn rad_cvt_addr ,
323 .Fn rad_cvt_int ,
324 and
325 .Fn rad_cvt_string .
326 These functions accept a pointer to the attribute data, which should
327 have been obtained using
328 .Fn rad_get_attr
329 and optionally
330 .Fn rad_get_vendor_attr .
331 In the case of
332 .Fn rad_cvt_string ,
333 the length
334 .Va len
335 must also be given. These functions interpret the attribute as an
336 Internet address, an integer, or a string, respectively, and return
337 its value.
338 .Fn rad_cvt_string
339 returns its value as a NUL-terminated string in dynamically
340 allocated memory. The application should free the string using
341 .Xr free 3
342 when it is no longer needed.
343 .Pp
344 If insufficient virtual memory is available,
345 .Fn rad_cvt_string
346 returns
347 .Dv NULL .
348 .Fn rad_cvt_addr
349 and
350 .Fn rad_cvt_int
351 cannot fail.
352 .Pp
353 The
354 .Fn rad_request_authenticator
355 function may be used to obtain the Request-Authenticator attribute value
356 associated with the current RADIUS server according to the supplied
357 rad_handle.
358 The target buffer
359 .Ar buf
360 of length
361 .Ar len
362 must be supplied and should be at least 16 bytes.
363 The return value is the number of bytes written to
364 .Ar buf
365 or -1 to indicate that
366 .Ar len
367 was not large enough.
368 .Pp
369 The
370 .Fn rad_server_secret
371 returns the secret shared with the current RADIUS server according to the
372 supplied rad_handle.
373 .Sh OBTAINING ERROR MESSAGES
374 Those functions which accept a
375 .Va struct rad_handle *
376 argument record an error message if they fail. The error message
377 can be retrieved by calling
378 .Fn rad_strerror .
379 The message text is overwritten on each new error for the given
380 .Va struct rad_handle * .
381 Thus the message must be copied if it is to be preserved through
382 subsequent library calls using the same handle.
383 .Sh CLEANUP
384 To free the resources used by the RADIUS library, call
385 .Fn rad_close .
386 .Sh RETURN VALUES
387 The following functions return a non-negative value on success. If
388 they detect an error, they return -1 and record an error message
389 which can be retrieved using
390 .Fn rad_strerror .
391 .Pp
392 .Bl -item -offset indent -compact
393 .It
394 .Fn rad_add_server
395 .It
396 .Fn rad_config
397 .It
398 .Fn rad_create_request
399 .It
400 .Fn rad_get_attr
401 .It
402 .Fn rad_put_addr
403 .It
404 .Fn rad_put_attr
405 .It
406 .Fn rad_put_int
407 .It
408 .Fn rad_put_string
409 .It
410 .Fn rad_init_send_request
411 .It
412 .Fn rad_continue_send_request
413 .It
414 .Fn rad_send_request
415 .El
416 .Pp
417 The following functions return a
418 .No non- Ns Dv NULL
419 pointer on success. If they are unable to allocate sufficient
420 virtual memory, they return
421 .Dv NULL ,
422 without recording an error message.
423 .Pp
424 .Bl -item -offset indent -compact
425 .It
426 .Fn rad_acct_open
427 .It
428 .Fn rad_auth_open
429 .It
430 .Fn rad_cvt_string
431 .El
432 .Sh FILES
433 .Pa /etc/radius.conf
434 .Sh SEE ALSO
435 .Xr radius.conf 5
436 .Rs
437 .%A C. Rigney, et al
438 .%T "Remote Authentication Dial In User Service (RADIUS)"
439 .%O RFC 2138
440 .Re
441 .Rs
442 .%A C. Rigney
443 .%T RADIUS Accounting
444 .%O RFC 2139
445 .Re
446 .Sh AUTHORS
447 This software was originally written by
448 .An John Polstra ,
449 and donated to the
450 .Fx
451 project by Juniper Networks, Inc.
452 Oleg Semyonov subsequently added the ability to perform RADIUS
453 accounting.