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view lib/mldap/mldap.c @ 1797:cdb2e4e28d86
Removed string 'hint'
| author | bsw |
|---|---|
| date | Thu Oct 21 14:49:53 2021 +0200 (2021-10-21) |
| parents | ab837b075cf7 |
| children |
line source
1 /*
2 * minimalistic Lua LDAP interface library
3 *
4 * The library does not set any global variable itself and must thus be
5 * loaded with
6 *
7 * mldap = require("mldap")
8 *
9 * or a similar statement.
10 *
11 * The library provides two functions, conn = bind{...} and unbind(conn)
12 * to connect to and disconnect from the LDAP server respectively. The
13 * unbind function is also provided as a method of the connection userdata
14 * object (see below).
15 *
16 * The arguments to the bind{...} function are documented in the source code
17 * (see C function mldap_bind). In case of success, the bind function returns
18 * a userdata object that provides two methods: query{...} and unbind(). In
19 * case of error, the bind function returns nil as first return value, an
20 * error string as second return value, and a numeric error code as third
21 * return value. A positive error code is an LDAP resultCode, a negative
22 * error code is an OpenLDAP API error code:
23 *
24 * connection, error_string, numeric_error_code = mldap.bind{...}
25 *
26 * For translating numeric error codes to an identifying (machine readable)
27 * string identifier, the library provides in addition to the two functions
28 * a table named 'errorcodes', for example:
29 *
30 * 49 == mldap.errorcodes["invalid_credentials"]
31 *
32 * and
33 *
34 * mldap.errorcodes[49] == "invalid_credentials"
35 *
36 * The arguments and return value of the query{...} method of the connection
37 * userdata object are also documented in the source code below (see
38 * C function mldap_query). Error conditions are reported the same way as the
39 * bind{...} function does.
40 *
41 * To close the connection, either the unbind() function of the library or
42 * the unbind() method can be called; it is allowed to call them multiple
43 * times, and they are also invoked by the garbage collector.
44 *
45 */
47 // Lua header inclusions:
48 #include <lua.h>
49 #include <lauxlib.h>
51 // OpenLDAP header inclusions:
52 #include <ldap.h>
54 // Standard C inclusions:
55 #include <stdlib.h>
56 #include <stdbool.h>
57 #include <unistd.h>
59 // Error code translation is included from separate C file:
60 #include "mldap_errorcodes.c"
62 // Provide compatibility with Lua 5.1:
63 #if LUA_VERSION_NUM < 502
64 #define luaL_newlib(L, t) lua_newtable((L)); luaL_register(L, NULL, t)
65 #define lua_rawlen lua_objlen
66 #define lua_len lua_objlen
67 #define luaL_setmetatable(L, regkey) \
68 lua_getfield((L), LUA_REGISTRYINDEX, (regkey)); \
69 lua_setmetatable((L), -2);
70 #endif
72 // prefix for all Lua registry entries of this library:
73 #define MLDAP_REGKEY "556aeaf3c864af2e_mldap_"
76 static const char *mldap_get_named_string_arg(
77 // gets a named argument of type "string" from a table at the given stack position
79 lua_State *L, // pointer to lua_State variable
80 int idx, // stack index of the table containing the named arguments
81 const char *argname, // name of the argument
82 bool mandatory // if not 0, then the argument is mandatory and an error is raised if it isn't found
84 // leaves the string as new element on top of the stack
85 ) {
87 // pushes the table entry with the given argument name on top of the stack:
88 lua_getfield(L, idx, argname);
90 // check, if the entry is nil or false:
91 if (!lua_toboolean(L, -1)) {
93 // throw error, if named argument is mandatory:
94 if (mandatory) return luaL_error(L, "Named argument '%s' missing", argname), NULL;
96 // return NULL pointer, if named argument is not mandatory:
97 return NULL;
99 }
101 // throw error, if the value of the argument is not string:
102 if (lua_type(L, -1) != LUA_TSTRING) return luaL_error(L, "Named argument '%s' is not a string", argname), NULL;
104 // return a pointer to the string, leaving the string on top of the stack to avoid garbage collection:
105 return lua_tostring(L, -1);
107 // leaves one element on the stack
108 }
111 static int mldap_get_named_number_arg(
112 // gets a named argument of type "number" from a table at the given stack position
114 lua_State *L, // pointer to lua_State variable
115 int idx, // stack index of the table containing the named arguments
116 const char *argname, // name of the argument
117 bool mandatory, // if not 0, then the argument is mandatory and an error is raised if it isn't found
118 lua_Number default_value // default value to return, if the argument is not mandatory and nil
120 // opposed to 'mldap_get_named_string_arg', this function leaves no element on the stack
121 ) {
123 lua_Number value; // value to return
125 // pushes the table entry with the given argument name on top of the stack:
126 lua_getfield(L, idx, argname);
128 // check, if the entry is nil or false:
129 if (lua_isnil(L, -1)) {
131 // throw error, if named argument is mandatory:
132 if (mandatory) return luaL_error(L, "Named argument '%s' missing", argname), 0;
134 // set default value as return value, if named argument is not mandatory:
135 value = default_value;
137 } else {
139 // throw error, if the value of the argument is not a number:
140 if (lua_type(L, -1) != LUA_TNUMBER) return luaL_error(L, "Named argument '%s' is not a number", argname), 0;
142 // set return value to the number:
143 value = lua_tonumber(L, -1);
145 }
147 // remove unnecessary element from stack (not needed to avoid garbage collection):
148 lua_pop(L, 1);
150 return value;
152 // leaves no new elements on the stack
153 }
156 static bool mldap_get_named_boolean_arg(
157 // gets a named argument of type "boolean" from a table at the given stack position
159 lua_State *L, // pointer to lua_State variable
160 int idx, // stack index of the table containing the named arguments
161 const char *argname, // name of the argument
162 bool mandatory, // if not 0, then the argument is mandatory and an error is raised if it isn't found
163 bool default_value // default value to return, if the argument is not mandatory and nil
165 // opposed to 'mldap_get_named_string_arg', this function leaves no element on the stack
166 ) {
168 bool value; // value to return
170 // pushes the table entry with the given argument name on top of the stack:
171 lua_getfield(L, idx, argname);
173 // check, if the entry is nil:
174 if (lua_isnil(L, -1)) {
176 // throw error, if named argument is mandatory:
177 if (mandatory) return luaL_error(L, "Named argument '%s' missing", argname), 0;
179 // set default value as return value, if named argument is not mandatory:
180 value = default_value;
182 } else {
184 // throw error, if the value of the argument is not a number:
185 if (lua_type(L, -1) != LUA_TBOOLEAN) return luaL_error(L, "Named argument '%s' is not a boolean", argname), 0;
187 // set return value to the number:
188 value = lua_toboolean(L, -1);
190 }
192 // remove unnecessary element from stack (not needed to avoid garbage collection):
193 lua_pop(L, 1);
195 return value;
197 // leaves no new elements on the stack
198 }
201 static int mldap_scope(
202 // converts a string ("base", "onelevel", "subtree", "children") to an integer representing the LDAP scope
203 // and throws an error for any unknown string
205 lua_State *L, // pointer to lua_State variable (needed to throw errors)
206 const char *scope_string // string that is either ("base", "onelevel", "subtree", "children")
208 // does not affect or use the Lua stack at all
209 ) {
211 // return integer according to string value:
212 if (!strcmp(scope_string, "base")) return LDAP_SCOPE_BASE;
213 if (!strcmp(scope_string, "onelevel")) return LDAP_SCOPE_ONELEVEL;
214 if (!strcmp(scope_string, "subtree")) return LDAP_SCOPE_SUBTREE;
215 if (!strcmp(scope_string, "children")) return LDAP_SCOPE_CHILDREN;
217 // throw error for unknown string values:
218 return luaL_error(L, "Invalid LDAP scope: '%s'", scope_string), 0;
220 }
223 static int mldap_bind(lua_State *L) {
224 // Lua C function that takes named arguments as a table
225 // and returns a userdata object, representing the LDAP connection
226 // or returns nil, an error string, and an error code (integer) on error
228 // named arguments:
229 // "uri" (string) server URI to connect to
230 // "who" (string) DN to bind as
231 // "password" (string) password for DN to bind as
232 // "timeout" (number) timeout in seconds
233 // "tls" (boolean) use TLS
235 static const int ldap_version = LDAP_VERSION3; // providing a pointer (&ldap_version) to set LDAP protocol version 3
236 const char *uri; // C string for "uri" argument
237 bool tls; // boolean indicating if TLS is to be used
238 const char *who; // C string for "who" argument
239 struct berval cred; // credentials ("password") are stored as struct berval
240 lua_Number timeout_float; // float (lua_Number) for timeout
241 struct timeval timeout; // timeout is stored as struct timeval
242 int ldap_error; // LDAP error code (as returned by libldap calls)
243 LDAP *ldp; // pointer to an opaque OpenLDAP structure representing the connection
244 LDAP **ldp_ptr; // pointer to a Lua userdata structure (that only contains the 'ldp' pointer)
246 // throw error if first argument is not a table:
247 if (lua_type(L, 1) != LUA_TTABLE) {
248 luaL_error(L, "Argument to function 'bind' is not a table.");
249 }
251 // extract arguments:
252 uri = mldap_get_named_string_arg(L, 1, "uri", true);
253 tls = mldap_get_named_boolean_arg(L, 1, "tls", false, false);
254 who = mldap_get_named_string_arg(L, 1, "who", false);
255 cred.bv_val = (char *)mldap_get_named_string_arg(L, 1, "password", false);
256 // use (char *) cast to suppress compiler warning (should be const anyway)
257 if (cred.bv_val) cred.bv_len = strlen(cred.bv_val);
258 else cred.bv_len = 0;
259 timeout_float = mldap_get_named_number_arg(L, 1, "timeout", false, -1);
260 timeout.tv_sec = timeout_float;
261 timeout.tv_usec = (timeout_float - timeout.tv_sec) * 1000000;
263 // initialize OpenLDAP structure and provide URI for connection:
264 ldap_error = ldap_initialize(&ldp, uri);
265 // on error, jump to label "mldap_queryconn_error1", as no ldap_unbind_ext_s() is needed:
266 if (ldap_error != LDAP_SUCCESS) goto mldap_queryconn_error1;
268 // set LDAP protocol version 3:
269 ldap_error = ldap_set_option(ldp, LDAP_OPT_PROTOCOL_VERSION, &ldap_version);
270 // on error, jump to label "mldap_queryconn_error2", as ldap_unbind_ext_s() must be called:
271 if (ldap_error != LDAP_SUCCESS) goto mldap_queryconn_error2;
273 // set timeout for asynchronous OpenLDAP library calls:
274 ldap_error = ldap_set_option(ldp, LDAP_OPT_TIMEOUT, &timeout);
275 // on error, jump to label "mldap_queryconn_error2", as ldap_unbind_ext_s() must be called:
276 if (ldap_error != LDAP_SUCCESS) goto mldap_queryconn_error2;
278 // initiate TLS if requested
279 if (tls) {
280 ldap_error = ldap_start_tls_s(ldp, NULL, NULL);
281 if (ldap_error != LDAP_SUCCESS) goto mldap_queryconn_error2;
282 }
284 // connect to LDAP server:
285 ldap_error = ldap_sasl_bind_s(
286 ldp, // pointer to opaque OpenLDAP structure representing the connection
287 who, // DN to bind as
288 LDAP_SASL_SIMPLE, // SASL mechanism "simple" for password authentication
289 &cred, // password as struct berval
290 NULL, // no server controls
291 NULL, // no client controls
292 NULL // do not store server credentials
293 );
295 // error handling:
296 if (ldap_error != LDAP_SUCCESS) {
298 // error label to jump to, if a call of ldap_unbind_ext_s() is required:
299 mldap_queryconn_error2:
301 // close connection and free resources:
302 ldap_unbind_ext_s(ldp, NULL, NULL);
304 // error label to jump to, if no call of ldap_unbind_ext_s() is required:
305 mldap_queryconn_error1:
307 // return three values:
308 lua_pushnil(L); // return nil as first value
309 lua_pushstring(L, ldap_err2string(ldap_error)); // return error string as second value
310 lua_pushinteger(L, ldap_error); // return error code (integer) as third value
311 return 3;
313 }
315 // create new Lua userdata object (that will contain the 'ldp' pointer) on top of stack:
316 ldp_ptr = lua_newuserdata(L, sizeof(LDAP *));
318 // set metatable of Lua userdata object:
319 luaL_setmetatable(L, MLDAP_REGKEY "connection_metatable");
321 // write contents of Lua userdata object (the 'ldp' pointer):
322 *ldp_ptr = ldp;
324 // return Lua userdata object from top of stack:
325 return 1;
327 }
330 static int mldap_search(lua_State *L) {
331 // Lua C function used as "search" method of Lua userdata object representing the LDAP connection
332 // that takes a Lua userdata object (the LDAP connection) as first argument,
333 // a table with named arguments as second argument,
334 // and returns a result table on success (see below)
335 // or returns nil, an error string, and an error code (integer) on error
337 // named arguments:
338 // "base" (string) DN of the entry at which to start the search
339 // "scope" (string) scope of the search, one of:
340 // "base" to search the object itself
341 // "onelevel" to search the object's immediate children
342 // "subtree" to search the object and all its descendants
343 // "children" to search all of the descendants
344 // "filter" (string) string representation of the filter to apply in the search
345 // (conforming to RFC 4515 as extended in RFC 4526)
346 // "attrs" (table) list of attribute descriptions (each a string) to return from matching entries
348 // structure of result table:
349 // {
350 // { dn = <distinguished name (DN)>,
351 // <attr1> = { <value1>, <value2>, ... },
352 // <attr2> = { <value1>, <value2>, ... },
353 // ...
354 // },
355 // { dn = <distinguished name (DN)>,
356 // <attr1> = { <value1>, <value2>, ... },
357 // <attr2> = { <value1>, <value2>, ... },
358 // ...
359 // },
360 // ...
361 // }
363 const char *base; // C string for "base" argument
364 const char *scope_string; // C string for "scope" argument
365 int scope; // integer representing the scope
366 const char *filter; // C string for "filter" argument
367 size_t nattrs; // number of attributes in "attrs" argument
368 const char **attrs; // C string array of "attrs" argument
369 size_t attr_idx; // index variable for building the C string array of "attrs"
370 int ldap_error; // LDAP error code (as returned by libldap calls)
371 LDAP **ldp_ptr; // pointer to a pointer to the OpenLDAP structure representing the connection
372 LDAPMessage *res; // pointer to the result of ldap_search_ext_s() call
373 LDAPMessage *ent; // pointer to an entry in the result of ldap_search_ext_s() call
374 int i; // integer to fill the Lua table returned as result
376 // truncate the Lua stack to 2 elements:
377 lua_settop(L, 2);
379 // check if the first argument is a Lua userdata object with the correct metatable
380 // and get a C pointer to that userdata object:
381 ldp_ptr = luaL_checkudata(L, 1, MLDAP_REGKEY "connection_metatable");
383 // throw an error, if the connection has already been closed:
384 if (!*ldp_ptr) {
385 return luaL_error(L, "LDAP connection has already been closed");
386 }
388 // check if the second argument is a table, and throw an error if it's not a table:
389 if (lua_type(L, 2) != LUA_TTABLE) {
390 luaL_error(L, "Argument to function 'bind' is not a table.");
391 }
393 // extract named arguments (requires memory allocation for 'attrs'):
394 base = mldap_get_named_string_arg(L, 2, "base", true); // pushed to 3
395 scope_string = mldap_get_named_string_arg(L, 2, "scope", true); // pushed to 4
396 scope = mldap_scope(L, scope_string);
397 lua_pop(L, 1); // removes stack element 4
398 filter = mldap_get_named_string_arg(L, 2, "filter", false); // pushed to 4
399 lua_getfield(L, 2, "attrs"); // pushed to 5
400 nattrs = luaL_len(L, -1);
401 attrs = calloc(nattrs + 1, sizeof(char *)); // memory allocation, +1 for terminating NULL
402 if (!attrs) return luaL_error(L, "Memory allocation error in C function 'mldap_queryconn'");
403 for (attr_idx=0; attr_idx<nattrs; attr_idx++) {
404 lua_pushinteger(L, attr_idx+1);
405 lua_gettable(L, 5); // pushed onto variable stack position
406 if (lua_type(L, -1) != LUA_TSTRING) {
407 free(attrs);
408 return luaL_error(L, "Element in attribute list is not a string");
409 }
410 attrs[attr_idx] = lua_tostring(L, -1);
411 }
412 // attrs[nattrs] = NULL; // unnecessary due to calloc
414 // execute LDAP search and store pointer to the result in 'res':
415 ldap_error = ldap_search_ext_s(
416 *ldp_ptr, // pointer to the opaque OpenLDAP structure representing the connection
417 base, // DN of the entry at which to start the search
418 scope, // scope of the search
419 filter, // string representation of the filter to apply in the search
420 (char **)attrs, // array of attribute descriptions (array of strings)
421 // cast to suppress compiler warning (should be const anyway)
422 0, // do not only request attribute descriptions but also values
423 NULL, // no server controls
424 NULL, // no client controls
425 NULL, // do not set another timeout
426 0, // no sizelimit
427 &res // store result in 'res'
428 );
430 // free data structures that have been allocated for the 'attrs' array:
431 free(attrs);
433 // return nil, an error string, and an error code (integer) in case of error:
434 if (ldap_error != LDAP_SUCCESS) {
435 lua_pushnil(L);
436 lua_pushstring(L, ldap_err2string(ldap_error));
437 lua_pushinteger(L, ldap_error);
438 return 3;
439 }
441 // clear Lua stack:
442 lua_settop(L, 0);
444 // create result table for all entries at stack position 1:
445 lua_newtable(L);
447 // use ldap_first_entry() and ldap_next_entry() functions
448 // to iterate through all entries in the result 'res'
449 // and count 'i' from 1 up:
450 for (
451 ent=ldap_first_entry(*ldp_ptr, res), i=1;
452 ent;
453 ent=ldap_next_entry(*ldp_ptr, ent), i++
454 ) {
456 char *attr; // name of attribute
457 BerElement *ber; // structure to iterate through attributes
458 char *dn; // LDAP entry name (distinguished name)
460 // create result table for one entry at stack position 2:
461 lua_newtable(L);
463 // use ldap_first_attribute() and ldap_next_attribute()
464 // as well as 'BerElement *ber' to iterate through all attributes
465 // ('ber' must be free'd with ber_free(ber, 0) call later):
466 for (
467 attr=ldap_first_attribute(*ldp_ptr, ent, &ber);
468 attr;
469 attr=ldap_next_attribute(*ldp_ptr, ent, ber)
470 ) {
472 struct berval **vals; // pointer to (first element of) array of values
473 struct berval **val; // pointer to a value represented as 'struct berval' structure
474 int j; // integer to fill a Lua table
476 // push the attribute name to Lua stack position 3:
477 lua_pushstring(L, attr);
479 // create a new table for the attribute's values on Lua stack position 4:
480 lua_newtable(L);
482 // call ldap_get_values_len() to obtain the values
483 // (required to be free'd later with ldap_value_free_len()):
484 vals = ldap_get_values_len(*ldp_ptr, ent, attr);
486 // iterate through values and count 'j' from 1 up:
487 for (val=vals, j=1; *val; val++, j++) {
489 // push value to Lua stack position 5:
490 lua_pushlstring(L, (*val)->bv_val, (*val)->bv_len);
492 // pop value from Lua stack position 5
493 // and store it in table on Lua stack position 4:
494 lua_rawseti(L, 4, j);
496 }
498 // free data structure of values:
499 ldap_value_free_len(vals);
501 // pop attribute name from Lua stack position 3
502 // and pop value table from Lua stack position 4
503 // and store them in result table for entry at Lua stack position 2:
504 lua_settable(L, 2);
506 }
508 // free 'BerElement *ber' stucture that has been used to iterate through all attributes
509 // (second argument is zero due to manpage of ldap_first_attribute()):
510 ber_free(ber, 0);
512 // store distinguished name (DN) on Lua stack position 3
513 // (aquired memory is free'd with ldap_memfree()):
514 dn = ldap_get_dn(*ldp_ptr, ent);
515 lua_pushstring(L, dn);
516 ldap_memfree(dn);
518 // pop distinguished name (DN) from Lua stack position 3
519 // and store it in field "dn" of entry result table at stack position 2
520 lua_setfield(L, 2, "dn");
522 // pop entry result table from Lua stack position 2
523 // and store it in table at stack position 1:
524 lua_rawseti(L, 1, i);
526 }
528 // return result table from top of Lua stack (stack position 1):
529 return 1;
531 }
533 static int mldap_unbind(lua_State *L) {
534 // Lua C function used as "unbind" function of module and "unbind" method of Lua userdata object
535 // closing the LDAP connection (if still open)
536 // returning nothing
538 LDAP **ldp_ptr; // pointer to a pointer to the OpenLDAP structure representing the connection
540 // check if the first argument is a Lua userdata object with the correct metatable
541 // and get a C pointer to that userdata object:
542 ldp_ptr = luaL_checkudata(L, 1, MLDAP_REGKEY "connection_metatable");
544 // check if the Lua userdata object still contains a pointer:
545 if (*ldp_ptr) {
547 // if it does, then call ldap_unbind_ext_s():
548 ldap_unbind_ext_s(
549 *ldp_ptr, // pointer to the opaque OpenLDAP structure representing the connection
550 NULL, // no server controls
551 NULL // no client controls
552 );
554 // store NULL pointer in Lua userdata to mark connection as closed
555 *ldp_ptr = NULL;
556 }
558 // returning nothing:
559 return 0;
561 }
564 // registration information for library functions:
565 static const struct luaL_Reg mldap_module_functions[] = {
566 {"bind", mldap_bind},
567 {"unbind", mldap_unbind},
568 {NULL, NULL}
569 };
572 // registration information for methods of connection object:
573 static const struct luaL_Reg mldap_connection_methods[] = {
574 {"search", mldap_search},
575 {"unbind", mldap_unbind},
576 {NULL, NULL}
577 };
580 // registration information for connection metatable:
581 static const struct luaL_Reg mldap_connection_metamethods[] = {
582 {"__gc", mldap_unbind},
583 {NULL, NULL}
584 };
587 // luaopen function to initialize/register library:
588 int luaopen_mldap(lua_State *L) {
590 // clear Lua stack:
591 lua_settop(L, 0);
593 // create table with library functions on Lua stack position 1:
594 luaL_newlib(L, mldap_module_functions);
596 // create metatable for connection objects on Lua stack position 2:
597 luaL_newlib(L, mldap_connection_metamethods);
599 // create table with methods for connection object on Lua stack position 3:
600 luaL_newlib(L, mldap_connection_methods);
602 // pop table with methods for connection object from Lua stack position 3
603 // and store it as "__index" in metatable:
604 lua_setfield(L, 2, "__index");
606 // pop table with metatable for connection objects from Lua stack position 2
607 // and store it in the Lua registry:
608 lua_setfield(L, LUA_REGISTRYINDEX, MLDAP_REGKEY "connection_metatable");
610 // create table for error code mappings on Lua stack position 2:
611 lua_newtable(L);
613 // fill table for error code mappings
614 // that maps integer error codes to error code strings
615 // and vice versa:
616 mldap_set_errorcodes(L);
618 // pop table for error code mappings from Lua stack position 2
619 // and store it as "errorcodes" in table with library functions:
620 lua_setfield(L, 1, "errorcodes");
622 // return table with library functions from top of Lua stack:
623 return 1;
625 }