1 .\" # DS - begin display
13 .TH unlang 5 "16 Jan 2008" "" "FreeRADIUS Processing un-language"
15 unlang \- FreeRADIUS Processing un\-language
17 FreeRADIUS supports a simple processing language in its configuration
18 files. We call it an "un-language" because the intention is NOT to
19 create yet another programming language. If you need something more
20 complicated than what is described here, we suggest using the Perl or
21 Python modules rlm_perl, or rlm_python.
23 The goal of the language is to allow simple policies to be written
24 with minimal effort. Those policies are then applied when a request
27 The keywords for the language are a combination of pre-defined
28 keywords, and references to loadable module names. We document only
29 the pre-defined keywords here.
31 Subject to a few limitations described below, any keyword can appear
32 in any context. The language consists of a series of entries, each
33 one one line. Each entry begins with a keyword. Entries are
34 organized into lists. Processing of the language is line by line,
35 from the start of the list to the end. Actions are executed
38 A reference to the named module. When processing reaches this point,
39 the pre-compiled module is called. The module may succeed or fail,
40 and will return a status to "unlang" if so. This status can be tested
41 in a condition. See the "Simple Conditions" text in the CONDITIONS
42 section, and MODULE RETURN CODES, below.
45 chap # call the CHAP module
47 sql # call the SQL module
53 Checks for a particular condition. If true, the block after the
54 condition is processed. Otherwise, the block is ignored. See
55 CONDITIONS, below, for documentation on the format of the conditions.
66 Define a block to be executed only if the previous "if" condition
78 Define a block to be executed only if the previous "if" condition
79 returned false, and if the specified condition evaluates to true.
90 Evaluate the given string, and choose the first matching "case"
91 statement inside of the current block. If the string is surrounded by
92 double quotes, it is expanded as described in the DATA TYPES section,
95 No statement other than "case" can appear in a "switch" block.
106 Define a static string to match a parent "switch" statement. The
107 strings given here are not expanded as is done with the parent
110 A "case" statement cannot appear outside of a "switch" block.
120 A default entry can be defined by omitting the static string. This
121 entry will be used if no other "case" entry matches. Only one default
122 entry can exist in a "switch" section.
133 Update a particular attribute list, based on the attributes given in
146 The <list> can be one of "request", "reply", "proxy-request",
147 "proxy-reply", or "control". The "control" list is the list of
148 attributes maintainted internally by the server that controls how the
149 server processes the request. Any attribute that does not go in a
150 packet on the network will generally be placed in the "control" list.
152 For backwards compatibility with older versions, "check" is accepted
153 as a synonym for "control". The use of "check" is deprecated, and
154 will be removed in a future release.
156 For EAP methods with tunneled authentication sessions (i.e. PEAP and
157 EAP-TTLS), the inner tunnel session can also reference
158 "outer.request", "outer.reply", and "outer.control". Those references
159 will update the relevant list in the outer tunnel session.
161 The only contents permitted in an "update" section are attributes and
162 values. The contents of the "update" section are described in the
163 ATTRIBUTES section below.
165 This section contains a simple list of modules. The first module is
166 called when the section is being processed. If the first module
167 succeeds in its operation, then the server stops processing the
168 section, and returns to the parent section.
170 If, however, the module fails, then the next module in the list is
171 tried, as described above. The processing continues until one module
172 succeeds, or until the list has been exhausted.
174 Redundant sections can contain only a list of modules, and cannot
175 contain keywords that perform conditional operations (if, else, etc)
176 or update an attribute list.
183 sql2 # try this only if sql1 fails.
190 This section contains a simple list of modules. When the section is
191 entered, one module is chosen at random to process the request. All
192 of the modules in the list should be the same type (e.g. ldap or sql).
193 All of the modules in the list should behave identically, otherwise
194 the load-balance section will return different results for the same
197 Load-balance sections can contain only a list of modules, and cannot
198 contain keywords that perform conditional operations (if, else, etc)
199 or update an attribute list.
204 ldap1 # 50% of requests go here
206 ldap2 # 50% of requests go here
211 In general, we recommend using "redundant-load-balance" instead of
213 .IP redundant-load-balance
214 This section contains a simple list of modules. When the section is
215 entered, one module is chosen at random to process the request. If
216 that module succeeds, then the server stops processing the section.
217 If, however, the module fails, then one of the remaining modules is
218 chosen at random to process the request. This process repeats until
219 one module succeeds, or until the list has been exhausted.
221 All of the modules in the list should be the same type (e.g. ldap or
222 sql). All of the modules in the list should behave identically,
223 otherwise the load-balance section will return different results for
226 Load-balance sections can contain only a list of modules, and cannot
227 contain keywords that perform conditional operations (if, else, etc)
228 or update an attribute list.
231 redundant-load-balance {
233 ldap1 # 50%, unless ldap2 is down, then 100%
235 ldap2 # 50%, unless ldap1 is down, then 100%
240 The conditions are similar to C conditions in syntax, though
241 quoted strings are supported, as with the Unix shell.
249 Evalutes to true if 'foo' is a non-empty string (single quotes, double
250 quotes, or back-quoted). Also evaluates to true if 'foo' is a
251 non-zero number. Note that the language is poorly typed, so the
252 string "0000" can be interpreted as a numerical zero. This issue can
253 be avoided by comparings strings to an empty string, rather than by
254 evaluating the string by itself.
256 If the word 'foo' is not a quoted string, then it can be taken as a
257 reference to a named attribute. See "Referencing attribute lists",
258 below, for examples of attribute references. The condition evaluates
259 to true if the named attribute exists.
261 Otherwise, if the word 'foo' is not a quoted string, and is not an
262 attribute reference, then it is interpreted as a reference to a module
263 return code. The condition evaluates to true if the most recent
264 module return code matches the name given here. Valid module return
265 codes are given in MODULE RETURN CODES, below.
271 Evalutes to true if 'foo' evaluates to false, and vice-versa.
273 Short-circuit operators
282 "&&" and "||" are short-circuit operators. "&&" evaluates the first
283 condition, and evaluates the second condition if and only if the
284 result of the first condition is true. "||" is similar, but executes
285 the second command if and only if the result of the first condition is
293 Compares 'foo' to 'bar', and evaluates to true if the comparison holds
294 true. Valid comparison operators are "==", "!=", "<", "<=", ">",
295 ">=", "=~", and "!~", all with their usual meanings. Invalid
296 comparison operators are ":=" and "=".
298 Conditions may be nested to any depth, subject only to line length
299 limitations (8192 bytes).
301 There are only a few data types supported in the language. Reference
302 to attributes, numbers, and strings. Any data type can appear in
303 stand-alone condition, in which case they are evaluated as described
304 in "Simple conditions", above. They can also appear (with some
305 exceptions noted below) on the left-hand or on the right-hand side of
308 Numbers are composed of decimal digits. Floating point, hex, and
309 octal numbers are not supported. The maximum value for a number is
310 machine-dependent, but is usually 32-bits, including one bit for a
315 Text that is not enclosed in quotes is interpreted differently
316 depending on where it occurs in a condition. On the left hand side of
317 a condition, it is interpreted as a reference to an attribute. On the
318 right hand side, it is interpreted as a simple string, in the same
319 manner as a single-quoted string.
321 Using attribute references permits limited type-specific comparisons,
322 as seen in the examples below.
325 if (User-Name == "bob") {
329 if (Framed-IP-Address > 127.0.0.1) {
333 if (Service-Type == Login-User) {
338 Double-quoted strings are expanded by inserting the value of any
339 variables (see VARIABLES, below) before being evaluated. If
340 the result is a number it is evaluated in a numerical context.
342 String length is limited by line-length, usually about 8000
343 characters. A double quote character (") can be used in a string via
344 the normal back-slash escaping method. ("like \\"this\\" !")
347 Single-quoted strings are evaluated as-is. Their values are not
348 expanded as with double-quoted strings above, and they are not
349 interpreted as attribute references.
351 Back-quoted strings are evaluated by expanding the contents of the
352 string, as described above for double-quoted strings. The resulting
353 command given inside of the string in a sub-shell, and taking the
354 output as a string. This behavior is much the same as that of Unix
357 Note that for security reasons, the input string is split into command
358 and arguments before variable expansion is done.
360 For performance reasons, we suggest that the use of back-quoted
361 strings be kept to a minimum. Executing external programs is
362 relatively expensive, and executing a large number of programs for
363 every request can quickly use all of the CPU time in a server. If you
364 believe that you need to execute many programs, we suggest finding
365 alternative ways to achieve the same result. In some cases, using a
366 real language may be sufficient.
368 These strings are valid only on the right-hand side of a comparison,
369 and then only when the comparison operator is "=~" or "!~". They are
370 regular expressions, as implemented by the local regular expression
371 library on the system. This is usually Posix regular expressions.
373 The trailing 'i' is optional, and indicates that the regular
374 expression match should be done in a case-insensitive fashion.
376 If the comparison operator is "=~", then parantheses in the regular
377 expression will define variables containing the matching text, as
378 described below in the VARIABLES section.
380 Run-time variables are referenced using the following syntax
386 Note that unlike C, there is no way to declare variables, or to refer
387 to them outside of a string context. All references to variables MUST
388 be contained inside of a double-quoted or back-quoted string.
390 Many potential variables are defined in the dictionaries that
391 accompany the server. These definitions define only the name and
392 type, and do not define the value of the variable. When the server
393 receives a packet, it uses the packet contents to look up entries in
394 the dictionary, and instantiates variables with a name taken from the
395 dictionaries, and a value taken from the packet contents. This
396 process means that if a variable does not exist, it is usually because
397 it was not mentioned in a packet that the server received.
399 Once the variable is instantiated, it is added to an appropriate
400 attribute list, as described below. In many cases, attributes and
401 variables are inter-changeble, and are often talked about that way.
402 However, variables can also refer to run-time calls to modules, which
403 may perform operations like SQL SELECTs, and which may return the
404 result as the value of the variable.
406 Referencing attribute lists
408 Attribute lists may be referenced via the following syntax
411 %{<list>:Attribute-Name}
414 Where <list> is one of "request", "reply", "proxy-request",
415 "proxy-reply", "control", "outer.request", "outer.reply", or
416 "outer.control", as described above for the "update" section. The
417 "<list>:" prefix is optional, and if omitted, is assumed to refer to
420 When a variable is encountered, the given list is examined for an
421 attribute of the given name. If found, the variable reference in the
422 string is replaced with the value of that attribute. Some examples are:
427 %{request:User-Name} # same as above
433 Results of regular expression matches
435 If a regular expression match has previously been performed, then the
436 special variable %{0} will contain a copy of the input string. The
437 variables %{1} through %{8} will contain the substring matches,
438 starting from the left-most parantheses, and onwards. If there are
439 more than 8 parantheses, the additional results will not be placed
443 Obtaining results from databases
445 It is useful to query a database for some information, and to use the
446 result in a condition. The following syntax will call a module, pass
447 it the given string, and replace the variable reference with the
448 resulting string returned from the module.
451 %{module: string ...}
454 The syntax of the string is module-specific. Please read the module
455 documentation for additional details.
460 Conditional syntax similar to that used in Unix shells may also be
463 If %{Foo} has a value, returns that value.
465 Otherwise, returns literal string "bar".
466 .IP %{%{Foo}:-%{Bar}}
467 If %{Foo} has a value, returns that value.
469 Otherwise, returns the expansion of %{Bar}.
471 These conditional expansions can be nested to almost any depth, such
472 as with %{%{One}:-%{%{Two}:-%{Three}}}
475 String lengths and arrays
477 Similar to a Unix shell, there are ways to reference string lenths,
478 and the second or more instance of an attribute in a list. If you
479 need this functionality, we recommend using a real language.
481 The number of characters in %{string}. If %{string} is not
482 set, then the length is not set.
484 e.g. %{#Junk-junk:-foo} will yeild the string "foo".
485 .IP %{Attribute-Name[index]}
486 Reference the N'th occurance of the given attribute. The syntax
487 %{<list>:Attribute-Name[index]} may also be used. The indexes start
488 at zero. This feature is NOT available for non-attribute dynamic
489 translations, like %{sql:...}.
491 For example, %{User-Name[0]} is the same as %{User-Name}
493 The variable %{Cisco-AVPair[2]} will reference the value of the
494 THIRD Cisco-AVPair attribute (if it exists) in the request packet,
495 .IP %{Attribute-Name[#]}
496 Returns the total number of attributes of that name in the relevant
497 attribute list. The number will usually be between 0 and 200.
499 For most requests, %{request:User-Name[#]} == 1
500 .IP %{Attribute-Name[*]}
501 Expands to a single string, with the value of each array
502 member separated by a newline.
503 .IP %{#Attribute-Name[index]}
504 Expands to the length of the string %{Attribute-Name[index]}.
506 The attribute lists described above may be edited by listing one or
507 more attributes in an "update" section. Once the attributes have been
508 defined, they may be referenced as described above in the VARIABLES
511 The following syntax defines attributes in an "update" section. Each
512 attribute and value has to be all on one line in the configuration
513 file. There is no need for commas or semi-colons after the value.
516 Attribute-Name = value
521 The Attribute-Name must be a name previously defined in a dictionary.
522 If an undefined name is used, the server will return an error, and
526 The operator used to assign the value of the attribute may be one of
527 the following, with the given meaning.
530 Add the attribute to the list, if and only if an attribute of the same
531 name is already present in that list.
533 Add the attribute to the list. If any attribute of the same name is
534 already present in that list, its value is replaced with the value of
535 the current attribute.
537 Add the attribute to the tail of the list, even if attributes of the
538 same name are already present in the list.
541 Enforcement and Filtering Operators
543 The following operators may also be used in addition to the ones
544 listed above. Their function is to perform enforcement or filtering
545 on attributes in a list.
547 Remove all matching attributes from the list. Both the attribute name
548 and value have to match in order for the attribute to be removed from
551 Remove all non-matching attributes from the list. Both the attribute
552 name and value have to match in order for the attribute to remain in
555 Note that this operator is very different than the '=' operator listed
558 Enforce that the integer value of the attribute is less than or equal
559 to the value given here. If there is no attribute of the same name in
560 the list, the attribute is added with the given value, is with "+=".
561 If an attribute in the list exists, and has value less than given
562 here, it's value is unchanged. If an attribute in the list exists,
563 and has a value greater than given here, then that value is replaced
564 with the one given here.
566 This operator is valid only for attributes of integer type.
568 Enforce that the integer value of the attribute is greater than or
569 equal to the value given here. If there is no attribute of the same
570 name in the list, the attribute is added with the given value, is with
571 "+=". If an attribute in the list exists, and has value greater than
572 given here, it's value is unchanged. If an attribute in the list
573 exists, and has value less than given here, then that value is
574 replaced with the one given here.
576 This operator is valid only for attributes of integer type.
580 The format of the value is attribute-specific, and is usually a
581 string, integer, IP address, etc. Prior to the attribute being
582 instantiated, the value may be expanded as described above in the DATA
583 TYPES section, above. This flexibility means that, for example, you
584 can assign an IP address value to an attribute by specifying the IP
585 address directly, or by having the address returned from a database
586 query, or by having the address returned as the output of a program
589 When string values are finally assigned to a variable, they can have a
590 maximum length of 253 characters. This limit is due in part to both
591 protocol and internal server requirements. That is, the strings in
592 the language can be nearly 8k in length, say for a long SQL query.
593 However, the output of that SQL query should be no more than 253
594 characters in length.
596 Other keywords in the language are taken from the names of modules
597 loaded by the server. These keywords are dependent on both the
598 modules, and the local configuration.
600 Some use keywords that are defined in the default configuration file
603 Cause the request to be treated as if a database failure had occurred.
605 Do nothing. This also serves as an instruction to the configurable
606 failover tracking that nothing was done in the current section.
608 Instructs the server that the request was processed properly. This
609 keyword can be used to over-ride earlier failures, if the local
610 administrator determines that the faiures are not catastrophic.
612 Causes the request to be immediately rejected
613 .SH MODULE RETURN CODES
614 When a module is called, it returns one of the following codes to
615 "unlang", with the following meaning.
618 notfound information was not found
620 noop the module did nothing
622 ok the module succeeded
624 updated the module updated the request
626 fail the module failed
628 reject the module rejected the request
630 userlock the user was locked out
632 invalid the configuration was invalid
634 handled the module has handled the request itself
637 These return codes can be tested for in a condition, as described
638 above in the CONDITIONS section.
640 /etc/raddb/radiusd.conf
642 .BR radiusd.conf (5),
645 Alan DeKok <aland@deployingradius.com>
projects / freeradius.git / blob