main/pbx: Move custom function routines to pbx_functions.c.
authorCorey Farrell <git@cfware.com>
Thu, 31 Dec 2015 02:51:47 +0000 (21:51 -0500)
committerCorey Farrell <git@cfware.com>
Fri, 1 Jan 2016 18:48:36 +0000 (13:48 -0500)
This is the second patch in a series meant to reduce the bulk of pbx.c.
This moves custom function management routines to their own source.

Change-Id: I34a6190282f781cdbbd3ce9d3adeac3c3805e177

include/asterisk/_private.h
main/asterisk.c
main/pbx.c
main/pbx_functions.c [new file with mode: 0644]

index e58828c..fb80434 100644 (file)
@@ -18,6 +18,7 @@
 int load_modules(unsigned int);                /*!< Provided by loader.c */
 int load_pbx(void);                    /*!< Provided by pbx.c */
 int load_pbx_builtins(void);   /*!< Provided by pbx_builtins.c */
+int load_pbx_functions_cli(void);      /*!< Provided by pbx_functions.c */
 int init_logger(void);                 /*!< Provided by logger.c */
 void close_logger(void);               /*!< Provided by logger.c */
 void logger_queue_start(void);         /*!< Provided by logger.c */
index a72e249..ec49c65 100644 (file)
@@ -4600,6 +4600,11 @@ static void asterisk_daemon(int isroot, const char *runuser, const char *rungrou
                exit(1);
        }
 
+       if (load_pbx_functions_cli()) {
+               printf("Failed: load_pbx_functions_cli\n%s", term_quit());
+               exit(1);
+       }
+
        if (ast_local_init()) {
                printf("Failed: ast_local_init\n%s", term_quit());
                exit(1);
index c54eca8..cfc3f62 100644 (file)
@@ -229,17 +229,6 @@ struct ast_app;
 
 AST_THREADSTORAGE(switch_data);
 AST_THREADSTORAGE(extensionstate_buf);
-/*!
- * \brief A thread local indicating whether the current thread can run
- * 'dangerous' dialplan functions.
- */
-AST_THREADSTORAGE(thread_inhibit_escalations_tl);
-
-/*!
- * \brief Set to true (non-zero) to globally allow all dangerous dialplan
- * functions to run.
- */
-static int live_dangerously;
 
 /*!
    \brief ast_exten: An extension
@@ -759,13 +748,6 @@ AST_MUTEX_DEFINE_STATIC(maxcalllock);
 static int countcalls;
 static int totalcalls;
 
-/*!
- * \brief Registered functions container.
- *
- * It is sorted by function name.
- */
-static AST_RWLIST_HEAD_STATIC(acf_root, ast_custom_function);
-
 static struct ast_context *contexts;
 static struct ast_hashtab *contexts_table = NULL;
 
@@ -3160,632 +3142,6 @@ static struct ast_custom_function exception_function = {
        .read = acf_exception_read,
 };
 
-static char *handle_show_functions(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
-{
-       struct ast_custom_function *acf;
-       int count_acf = 0;
-       int like = 0;
-
-       switch (cmd) {
-       case CLI_INIT:
-               e->command = "core show functions [like]";
-               e->usage =
-                       "Usage: core show functions [like <text>]\n"
-                       "       List builtin functions, optionally only those matching a given string\n";
-               return NULL;
-       case CLI_GENERATE:
-               return NULL;
-       }
-
-       if (a->argc == 5 && (!strcmp(a->argv[3], "like")) ) {
-               like = 1;
-       } else if (a->argc != 3) {
-               return CLI_SHOWUSAGE;
-       }
-
-       ast_cli(a->fd, "%s Custom Functions:\n--------------------------------------------------------------------------------\n", like ? "Matching" : "Installed");
-
-       AST_RWLIST_RDLOCK(&acf_root);
-       AST_RWLIST_TRAVERSE(&acf_root, acf, acflist) {
-               if (!like || strstr(acf->name, a->argv[4])) {
-                       count_acf++;
-                       ast_cli(a->fd, "%-20.20s  %-35.35s  %s\n",
-                               S_OR(acf->name, ""),
-                               S_OR(acf->syntax, ""),
-                               S_OR(acf->synopsis, ""));
-               }
-       }
-       AST_RWLIST_UNLOCK(&acf_root);
-
-       ast_cli(a->fd, "%d %scustom functions installed.\n", count_acf, like ? "matching " : "");
-
-       return CLI_SUCCESS;
-}
-
-static char *complete_functions(const char *word, int pos, int state)
-{
-       struct ast_custom_function *cur;
-       char *ret = NULL;
-       int which = 0;
-       int wordlen;
-       int cmp;
-
-       if (pos != 3) {
-               return NULL;
-       }
-
-       wordlen = strlen(word);
-       AST_RWLIST_RDLOCK(&acf_root);
-       AST_RWLIST_TRAVERSE(&acf_root, cur, acflist) {
-               /*
-                * Do a case-insensitive search for convenience in this
-                * 'complete' function.
-                *
-                * We must search the entire container because the functions are
-                * sorted and normally found case sensitively.
-                */
-               cmp = strncasecmp(word, cur->name, wordlen);
-               if (!cmp) {
-                       /* Found match. */
-                       if (++which <= state) {
-                               /* Not enough matches. */
-                               continue;
-                       }
-                       ret = ast_strdup(cur->name);
-                       break;
-               }
-       }
-       AST_RWLIST_UNLOCK(&acf_root);
-
-       return ret;
-}
-
-static char *handle_show_function(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
-{
-       struct ast_custom_function *acf;
-       /* Maximum number of characters added by terminal coloring is 22 */
-       char infotitle[64 + AST_MAX_APP + 22], syntitle[40], destitle[40], argtitle[40], seealsotitle[40];
-       char info[64 + AST_MAX_APP], *synopsis = NULL, *description = NULL, *seealso = NULL;
-       char stxtitle[40], *syntax = NULL, *arguments = NULL;
-       int syntax_size, description_size, synopsis_size, arguments_size, seealso_size;
-
-       switch (cmd) {
-       case CLI_INIT:
-               e->command = "core show function";
-               e->usage =
-                       "Usage: core show function <function>\n"
-                       "       Describe a particular dialplan function.\n";
-               return NULL;
-       case CLI_GENERATE:
-               return complete_functions(a->word, a->pos, a->n);
-       }
-
-       if (a->argc != 4) {
-               return CLI_SHOWUSAGE;
-       }
-
-       if (!(acf = ast_custom_function_find(a->argv[3]))) {
-               ast_cli(a->fd, "No function by that name registered.\n");
-               return CLI_FAILURE;
-       }
-
-       syntax_size = strlen(S_OR(acf->syntax, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
-       if (!(syntax = ast_malloc(syntax_size))) {
-               ast_cli(a->fd, "Memory allocation failure!\n");
-               return CLI_FAILURE;
-       }
-
-       snprintf(info, sizeof(info), "\n  -= Info about function '%s' =- \n\n", acf->name);
-       term_color(infotitle, info, COLOR_MAGENTA, 0, sizeof(infotitle));
-       term_color(syntitle, "[Synopsis]\n", COLOR_MAGENTA, 0, 40);
-       term_color(destitle, "[Description]\n", COLOR_MAGENTA, 0, 40);
-       term_color(stxtitle, "[Syntax]\n", COLOR_MAGENTA, 0, 40);
-       term_color(argtitle, "[Arguments]\n", COLOR_MAGENTA, 0, 40);
-       term_color(seealsotitle, "[See Also]\n", COLOR_MAGENTA, 0, 40);
-       term_color(syntax, S_OR(acf->syntax, "Not available"), COLOR_CYAN, 0, syntax_size);
-#ifdef AST_XML_DOCS
-       if (acf->docsrc == AST_XML_DOC) {
-               arguments = ast_xmldoc_printable(S_OR(acf->arguments, "Not available"), 1);
-               synopsis = ast_xmldoc_printable(S_OR(acf->synopsis, "Not available"), 1);
-               description = ast_xmldoc_printable(S_OR(acf->desc, "Not available"), 1);
-               seealso = ast_xmldoc_printable(S_OR(acf->seealso, "Not available"), 1);
-       } else
-#endif
-       {
-               synopsis_size = strlen(S_OR(acf->synopsis, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
-               synopsis = ast_malloc(synopsis_size);
-
-               description_size = strlen(S_OR(acf->desc, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
-               description = ast_malloc(description_size);
-
-               arguments_size = strlen(S_OR(acf->arguments, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
-               arguments = ast_malloc(arguments_size);
-
-               seealso_size = strlen(S_OR(acf->seealso, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
-               seealso = ast_malloc(seealso_size);
-
-               /* check allocated memory. */
-               if (!synopsis || !description || !arguments || !seealso) {
-                       ast_free(synopsis);
-                       ast_free(description);
-                       ast_free(arguments);
-                       ast_free(seealso);
-                       ast_free(syntax);
-                       return CLI_FAILURE;
-               }
-
-               term_color(arguments, S_OR(acf->arguments, "Not available"), COLOR_CYAN, 0, arguments_size);
-               term_color(synopsis, S_OR(acf->synopsis, "Not available"), COLOR_CYAN, 0, synopsis_size);
-               term_color(description, S_OR(acf->desc, "Not available"), COLOR_CYAN, 0, description_size);
-               term_color(seealso, S_OR(acf->seealso, "Not available"), COLOR_CYAN, 0, seealso_size);
-       }
-
-       ast_cli(a->fd, "%s%s%s\n\n%s%s\n\n%s%s\n\n%s%s\n\n%s%s\n",
-                       infotitle, syntitle, synopsis, destitle, description,
-                       stxtitle, syntax, argtitle, arguments, seealsotitle, seealso);
-
-       ast_free(arguments);
-       ast_free(synopsis);
-       ast_free(description);
-       ast_free(seealso);
-       ast_free(syntax);
-
-       return CLI_SUCCESS;
-}
-
-static struct ast_custom_function *ast_custom_function_find_nolock(const char *name)
-{
-       struct ast_custom_function *cur;
-       int cmp;
-
-       AST_RWLIST_TRAVERSE(&acf_root, cur, acflist) {
-               cmp = strcmp(name, cur->name);
-               if (cmp > 0) {
-                       continue;
-               }
-               if (!cmp) {
-                       /* Found it. */
-                       break;
-               }
-               /* Not in container. */
-               cur = NULL;
-               break;
-       }
-
-       return cur;
-}
-
-struct ast_custom_function *ast_custom_function_find(const char *name)
-{
-       struct ast_custom_function *acf;
-
-       AST_RWLIST_RDLOCK(&acf_root);
-       acf = ast_custom_function_find_nolock(name);
-       AST_RWLIST_UNLOCK(&acf_root);
-
-       return acf;
-}
-
-int ast_custom_function_unregister(struct ast_custom_function *acf)
-{
-       struct ast_custom_function *cur;
-
-       if (!acf) {
-               return -1;
-       }
-
-       AST_RWLIST_WRLOCK(&acf_root);
-       if ((cur = AST_RWLIST_REMOVE(&acf_root, acf, acflist))) {
-#ifdef AST_XML_DOCS
-               if (cur->docsrc == AST_XML_DOC) {
-                       ast_string_field_free_memory(acf);
-               }
-#endif
-               ast_verb(2, "Unregistered custom function %s\n", cur->name);
-       }
-       AST_RWLIST_UNLOCK(&acf_root);
-
-       return cur ? 0 : -1;
-}
-
-/*!
- * \brief Returns true if given custom function escalates privileges on read.
- *
- * \param acf Custom function to query.
- * \return True (non-zero) if reads escalate privileges.
- * \return False (zero) if reads just read.
- */
-static int read_escalates(const struct ast_custom_function *acf) {
-       return acf->read_escalates;
-}
-
-/*!
- * \brief Returns true if given custom function escalates privileges on write.
- *
- * \param acf Custom function to query.
- * \return True (non-zero) if writes escalate privileges.
- * \return False (zero) if writes just write.
- */
-static int write_escalates(const struct ast_custom_function *acf) {
-       return acf->write_escalates;
-}
-
-/*! \internal
- *  \brief Retrieve the XML documentation of a specified ast_custom_function,
- *         and populate ast_custom_function string fields.
- *  \param acf ast_custom_function structure with empty 'desc' and 'synopsis'
- *             but with a function 'name'.
- *  \retval -1 On error.
- *  \retval 0 On succes.
- */
-static int acf_retrieve_docs(struct ast_custom_function *acf)
-{
-#ifdef AST_XML_DOCS
-       char *tmpxml;
-
-       /* Let's try to find it in the Documentation XML */
-       if (!ast_strlen_zero(acf->desc) || !ast_strlen_zero(acf->synopsis)) {
-               return 0;
-       }
-
-       if (ast_string_field_init(acf, 128)) {
-               return -1;
-       }
-
-       /* load synopsis */
-       tmpxml = ast_xmldoc_build_synopsis("function", acf->name, ast_module_name(acf->mod));
-       ast_string_field_set(acf, synopsis, tmpxml);
-       ast_free(tmpxml);
-
-       /* load description */
-       tmpxml = ast_xmldoc_build_description("function", acf->name, ast_module_name(acf->mod));
-       ast_string_field_set(acf, desc, tmpxml);
-       ast_free(tmpxml);
-
-       /* load syntax */
-       tmpxml = ast_xmldoc_build_syntax("function", acf->name, ast_module_name(acf->mod));
-       ast_string_field_set(acf, syntax, tmpxml);
-       ast_free(tmpxml);
-
-       /* load arguments */
-       tmpxml = ast_xmldoc_build_arguments("function", acf->name, ast_module_name(acf->mod));
-       ast_string_field_set(acf, arguments, tmpxml);
-       ast_free(tmpxml);
-
-       /* load seealso */
-       tmpxml = ast_xmldoc_build_seealso("function", acf->name, ast_module_name(acf->mod));
-       ast_string_field_set(acf, seealso, tmpxml);
-       ast_free(tmpxml);
-
-       acf->docsrc = AST_XML_DOC;
-#endif
-
-       return 0;
-}
-
-int __ast_custom_function_register(struct ast_custom_function *acf, struct ast_module *mod)
-{
-       struct ast_custom_function *cur;
-
-       if (!acf) {
-               return -1;
-       }
-
-       acf->mod = mod;
-#ifdef AST_XML_DOCS
-       acf->docsrc = AST_STATIC_DOC;
-#endif
-
-       if (acf_retrieve_docs(acf)) {
-               return -1;
-       }
-
-       AST_RWLIST_WRLOCK(&acf_root);
-
-       cur = ast_custom_function_find_nolock(acf->name);
-       if (cur) {
-               ast_log(LOG_ERROR, "Function %s already registered.\n", acf->name);
-               AST_RWLIST_UNLOCK(&acf_root);
-               return -1;
-       }
-
-       /* Store in alphabetical order */
-       AST_RWLIST_TRAVERSE_SAFE_BEGIN(&acf_root, cur, acflist) {
-               if (strcmp(acf->name, cur->name) < 0) {
-                       AST_RWLIST_INSERT_BEFORE_CURRENT(acf, acflist);
-                       break;
-               }
-       }
-       AST_RWLIST_TRAVERSE_SAFE_END;
-       if (!cur) {
-               AST_RWLIST_INSERT_TAIL(&acf_root, acf, acflist);
-       }
-
-       AST_RWLIST_UNLOCK(&acf_root);
-
-       ast_verb(2, "Registered custom function '" COLORIZE_FMT "'\n", COLORIZE(COLOR_BRCYAN, 0, acf->name));
-
-       return 0;
-}
-
-int __ast_custom_function_register_escalating(struct ast_custom_function *acf, enum ast_custom_function_escalation escalation, struct ast_module *mod)
-{
-       int res;
-
-       res = __ast_custom_function_register(acf, mod);
-       if (res != 0) {
-               return -1;
-       }
-
-       switch (escalation) {
-       case AST_CFE_NONE:
-               break;
-       case AST_CFE_READ:
-               acf->read_escalates = 1;
-               break;
-       case AST_CFE_WRITE:
-               acf->write_escalates = 1;
-               break;
-       case AST_CFE_BOTH:
-               acf->read_escalates = 1;
-               acf->write_escalates = 1;
-               break;
-       }
-
-       return 0;
-}
-
-/*! \brief return a pointer to the arguments of the function,
- * and terminates the function name with '\\0'
- */
-static char *func_args(char *function)
-{
-       char *args = strchr(function, '(');
-
-       if (!args) {
-               ast_log(LOG_WARNING, "Function '%s' doesn't contain parentheses.  Assuming null argument.\n", function);
-       } else {
-               char *p;
-               *args++ = '\0';
-               if ((p = strrchr(args, ')'))) {
-                       *p = '\0';
-               } else {
-                       ast_log(LOG_WARNING, "Can't find trailing parenthesis for function '%s(%s'?\n", function, args);
-               }
-       }
-       return args;
-}
-
-void pbx_live_dangerously(int new_live_dangerously)
-{
-       if (new_live_dangerously && !live_dangerously) {
-               ast_log(LOG_WARNING, "Privilege escalation protection disabled!\n"
-                       "See https://wiki.asterisk.org/wiki/x/1gKfAQ for more details.\n");
-       }
-
-       if (!new_live_dangerously && live_dangerously) {
-               ast_log(LOG_NOTICE, "Privilege escalation protection enabled.\n");
-       }
-       live_dangerously = new_live_dangerously;
-}
-
-int ast_thread_inhibit_escalations(void)
-{
-       int *thread_inhibit_escalations;
-
-       thread_inhibit_escalations = ast_threadstorage_get(
-               &thread_inhibit_escalations_tl, sizeof(*thread_inhibit_escalations));
-
-       if (thread_inhibit_escalations == NULL) {
-               ast_log(LOG_ERROR, "Error inhibiting privilege escalations for current thread\n");
-               return -1;
-       }
-
-       *thread_inhibit_escalations = 1;
-       return 0;
-}
-
-/*!
- * \brief Indicates whether the current thread inhibits the execution of
- * dangerous functions.
- *
- * \return True (non-zero) if dangerous function execution is inhibited.
- * \return False (zero) if dangerous function execution is allowed.
- */
-static int thread_inhibits_escalations(void)
-{
-       int *thread_inhibit_escalations;
-
-       thread_inhibit_escalations = ast_threadstorage_get(
-               &thread_inhibit_escalations_tl, sizeof(*thread_inhibit_escalations));
-
-       if (thread_inhibit_escalations == NULL) {
-               ast_log(LOG_ERROR, "Error checking thread's ability to run dangerous functions\n");
-               /* On error, assume that we are inhibiting */
-               return 1;
-       }
-
-       return *thread_inhibit_escalations;
-}
-
-/*!
- * \brief Determines whether execution of a custom function's read function
- * is allowed.
- *
- * \param acfptr Custom function to check
- * \return True (non-zero) if reading is allowed.
- * \return False (zero) if reading is not allowed.
- */
-static int is_read_allowed(struct ast_custom_function *acfptr)
-{
-       if (!acfptr) {
-               return 1;
-       }
-
-       if (!read_escalates(acfptr)) {
-               return 1;
-       }
-
-       if (!thread_inhibits_escalations()) {
-               return 1;
-       }
-
-       if (live_dangerously) {
-               /* Global setting overrides the thread's preference */
-               ast_debug(2, "Reading %s from a dangerous context\n",
-                       acfptr->name);
-               return 1;
-       }
-
-       /* We have no reason to allow this function to execute */
-       return 0;
-}
-
-/*!
- * \brief Determines whether execution of a custom function's write function
- * is allowed.
- *
- * \param acfptr Custom function to check
- * \return True (non-zero) if writing is allowed.
- * \return False (zero) if writing is not allowed.
- */
-static int is_write_allowed(struct ast_custom_function *acfptr)
-{
-       if (!acfptr) {
-               return 1;
-       }
-
-       if (!write_escalates(acfptr)) {
-               return 1;
-       }
-
-       if (!thread_inhibits_escalations()) {
-               return 1;
-       }
-
-       if (live_dangerously) {
-               /* Global setting overrides the thread's preference */
-               ast_debug(2, "Writing %s from a dangerous context\n",
-                       acfptr->name);
-               return 1;
-       }
-
-       /* We have no reason to allow this function to execute */
-       return 0;
-}
-
-int ast_func_read(struct ast_channel *chan, const char *function, char *workspace, size_t len)
-{
-       char *copy = ast_strdupa(function);
-       char *args = func_args(copy);
-       struct ast_custom_function *acfptr = ast_custom_function_find(copy);
-       int res;
-       struct ast_module_user *u = NULL;
-
-       if (acfptr == NULL) {
-               ast_log(LOG_ERROR, "Function %s not registered\n", copy);
-       } else if (!acfptr->read && !acfptr->read2) {
-               ast_log(LOG_ERROR, "Function %s cannot be read\n", copy);
-       } else if (!is_read_allowed(acfptr)) {
-               ast_log(LOG_ERROR, "Dangerous function %s read blocked\n", copy);
-       } else if (acfptr->read) {
-               if (acfptr->mod) {
-                       u = __ast_module_user_add(acfptr->mod, chan);
-               }
-               res = acfptr->read(chan, copy, args, workspace, len);
-               if (acfptr->mod && u) {
-                       __ast_module_user_remove(acfptr->mod, u);
-               }
-               return res;
-       } else {
-               struct ast_str *str = ast_str_create(16);
-               if (acfptr->mod) {
-                       u = __ast_module_user_add(acfptr->mod, chan);
-               }
-               res = acfptr->read2(chan, copy, args, &str, 0);
-               if (acfptr->mod && u) {
-                       __ast_module_user_remove(acfptr->mod, u);
-               }
-               ast_copy_string(workspace, ast_str_buffer(str), len > ast_str_size(str) ? ast_str_size(str) : len);
-               ast_free(str);
-               return res;
-       }
-       return -1;
-}
-
-int ast_func_read2(struct ast_channel *chan, const char *function, struct ast_str **str, ssize_t maxlen)
-{
-       char *copy = ast_strdupa(function);
-       char *args = func_args(copy);
-       struct ast_custom_function *acfptr = ast_custom_function_find(copy);
-       int res;
-       struct ast_module_user *u = NULL;
-
-       if (acfptr == NULL) {
-               ast_log(LOG_ERROR, "Function %s not registered\n", copy);
-       } else if (!acfptr->read && !acfptr->read2) {
-               ast_log(LOG_ERROR, "Function %s cannot be read\n", copy);
-       } else if (!is_read_allowed(acfptr)) {
-               ast_log(LOG_ERROR, "Dangerous function %s read blocked\n", copy);
-       } else {
-               if (acfptr->mod) {
-                       u = __ast_module_user_add(acfptr->mod, chan);
-               }
-               ast_str_reset(*str);
-               if (acfptr->read2) {
-                       /* ast_str enabled */
-                       res = acfptr->read2(chan, copy, args, str, maxlen);
-               } else {
-                       /* Legacy function pointer, allocate buffer for result */
-                       int maxsize = ast_str_size(*str);
-                       if (maxlen > -1) {
-                               if (maxlen == 0) {
-                                       if (acfptr->read_max) {
-                                               maxsize = acfptr->read_max;
-                                       } else {
-                                               maxsize = VAR_BUF_SIZE;
-                                       }
-                               } else {
-                                       maxsize = maxlen;
-                               }
-                               ast_str_make_space(str, maxsize);
-                       }
-                       res = acfptr->read(chan, copy, args, ast_str_buffer(*str), maxsize);
-               }
-               if (acfptr->mod && u) {
-                       __ast_module_user_remove(acfptr->mod, u);
-               }
-               return res;
-       }
-       return -1;
-}
-
-int ast_func_write(struct ast_channel *chan, const char *function, const char *value)
-{
-       char *copy = ast_strdupa(function);
-       char *args = func_args(copy);
-       struct ast_custom_function *acfptr = ast_custom_function_find(copy);
-
-       if (acfptr == NULL) {
-               ast_log(LOG_ERROR, "Function %s not registered\n", copy);
-       } else if (!acfptr->write) {
-               ast_log(LOG_ERROR, "Function %s cannot be written to\n", copy);
-       } else if (!is_write_allowed(acfptr)) {
-               ast_log(LOG_ERROR, "Dangerous function %s write blocked\n", copy);
-       } else {
-               int res;
-               struct ast_module_user *u = NULL;
-               if (acfptr->mod)
-                       u = __ast_module_user_add(acfptr->mod, chan);
-               res = acfptr->write(chan, copy, args, value);
-               if (acfptr->mod && u)
-                       __ast_module_user_remove(acfptr->mod, u);
-               return res;
-       }
-
-       return -1;
-}
-
 void ast_str_substitute_variables_full(struct ast_str **buf, ssize_t maxlen, struct ast_channel *c, struct varshead *headp, const char *templ, size_t *used)
 {
        /* Substitutes variables into buf, based on string templ */
@@ -8054,7 +7410,6 @@ static struct ast_cli_entry pbx_cli[] = {
        AST_CLI_DEFINE(handle_eat_memory, "Eats all available memory"),
 #endif
        AST_CLI_DEFINE(handle_show_applications, "Shows registered dialplan applications"),
-       AST_CLI_DEFINE(handle_show_functions, "Shows registered dialplan functions"),
        AST_CLI_DEFINE(handle_show_switches, "Show alternative switches"),
        AST_CLI_DEFINE(handle_show_hints, "Show dialplan hints"),
        AST_CLI_DEFINE(handle_show_hint, "Show dialplan hint"),
@@ -8063,7 +7418,6 @@ static struct ast_cli_entry pbx_cli[] = {
        AST_CLI_DEFINE(handle_show_device2extenstate, "Show expected exten state from multiple device states"),
 #endif
        AST_CLI_DEFINE(handle_show_chanvar, "Show channel variables"),
-       AST_CLI_DEFINE(handle_show_function, "Describe a specific dialplan function"),
        AST_CLI_DEFINE(handle_show_hangup_all, "Show hangup handlers of all channels"),
        AST_CLI_DEFINE(handle_show_hangup_channel, "Show hangup handlers of a specified channel"),
        AST_CLI_DEFINE(handle_show_application, "Describe a specific dialplan application"),
diff --git a/main/pbx_functions.c b/main/pbx_functions.c
new file mode 100644 (file)
index 0000000..bc738b0
--- /dev/null
@@ -0,0 +1,723 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2015, CFWare, LLC
+ *
+ * Corey Farrell <git@cfware.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \brief Custom function management routines.
+ *
+ * \author Corey Farrell <git@cfware.com>
+ */
+
+/*** MODULEINFO
+       <support_level>core</support_level>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_REGISTER_FILE()
+
+#include "asterisk/_private.h"
+#include "asterisk/cli.h"
+#include "asterisk/linkedlists.h"
+#include "asterisk/module.h"
+#include "asterisk/pbx.h"
+#include "asterisk/term.h"
+#include "asterisk/threadstorage.h"
+#include "asterisk/xmldoc.h"
+#include "pbx_private.h"
+
+/*!
+ * \brief A thread local indicating whether the current thread can run
+ * 'dangerous' dialplan functions.
+ */
+AST_THREADSTORAGE(thread_inhibit_escalations_tl);
+
+/*!
+ * \brief Set to true (non-zero) to globally allow all dangerous dialplan
+ * functions to run.
+ */
+static int live_dangerously;
+
+/*!
+ * \brief Registered functions container.
+ *
+ * It is sorted by function name.
+ */
+static AST_RWLIST_HEAD_STATIC(acf_root, ast_custom_function);
+
+static char *handle_show_functions(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+       struct ast_custom_function *acf;
+       int count_acf = 0;
+       int like = 0;
+
+       switch (cmd) {
+       case CLI_INIT:
+               e->command = "core show functions [like]";
+               e->usage =
+                       "Usage: core show functions [like <text>]\n"
+                       "       List builtin functions, optionally only those matching a given string\n";
+               return NULL;
+       case CLI_GENERATE:
+               return NULL;
+       }
+
+       if (a->argc == 5 && (!strcmp(a->argv[3], "like")) ) {
+               like = 1;
+       } else if (a->argc != 3) {
+               return CLI_SHOWUSAGE;
+       }
+
+       ast_cli(a->fd, "%s Custom Functions:\n"
+               "--------------------------------------------------------------------------------\n",
+               like ? "Matching" : "Installed");
+
+       AST_RWLIST_RDLOCK(&acf_root);
+       AST_RWLIST_TRAVERSE(&acf_root, acf, acflist) {
+               if (!like || strstr(acf->name, a->argv[4])) {
+                       count_acf++;
+                       ast_cli(a->fd, "%-20.20s  %-35.35s  %s\n",
+                               S_OR(acf->name, ""),
+                               S_OR(acf->syntax, ""),
+                               S_OR(acf->synopsis, ""));
+               }
+       }
+       AST_RWLIST_UNLOCK(&acf_root);
+
+       ast_cli(a->fd, "%d %scustom functions installed.\n", count_acf, like ? "matching " : "");
+
+       return CLI_SUCCESS;
+}
+
+static char *complete_functions(const char *word, int pos, int state)
+{
+       struct ast_custom_function *cur;
+       char *ret = NULL;
+       int which = 0;
+       int wordlen;
+       int cmp;
+
+       if (pos != 3) {
+               return NULL;
+       }
+
+       wordlen = strlen(word);
+       AST_RWLIST_RDLOCK(&acf_root);
+       AST_RWLIST_TRAVERSE(&acf_root, cur, acflist) {
+               /*
+                * Do a case-insensitive search for convenience in this
+                * 'complete' function.
+                *
+                * We must search the entire container because the functions are
+                * sorted and normally found case sensitively.
+                */
+               cmp = strncasecmp(word, cur->name, wordlen);
+               if (!cmp) {
+                       /* Found match. */
+                       if (++which <= state) {
+                               /* Not enough matches. */
+                               continue;
+                       }
+                       ret = ast_strdup(cur->name);
+                       break;
+               }
+       }
+       AST_RWLIST_UNLOCK(&acf_root);
+
+       return ret;
+}
+
+static char *handle_show_function(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+       struct ast_custom_function *acf;
+       /* Maximum number of characters added by terminal coloring is 22 */
+       char infotitle[64 + AST_MAX_APP + 22], syntitle[40], destitle[40], argtitle[40], seealsotitle[40];
+       char info[64 + AST_MAX_APP], *synopsis = NULL, *description = NULL, *seealso = NULL;
+       char stxtitle[40], *syntax = NULL, *arguments = NULL;
+       int syntax_size, description_size, synopsis_size, arguments_size, seealso_size;
+
+       switch (cmd) {
+       case CLI_INIT:
+               e->command = "core show function";
+               e->usage =
+                       "Usage: core show function <function>\n"
+                       "       Describe a particular dialplan function.\n";
+               return NULL;
+       case CLI_GENERATE:
+               return complete_functions(a->word, a->pos, a->n);
+       }
+
+       if (a->argc != 4) {
+               return CLI_SHOWUSAGE;
+       }
+
+       if (!(acf = ast_custom_function_find(a->argv[3]))) {
+               ast_cli(a->fd, "No function by that name registered.\n");
+
+               return CLI_FAILURE;
+       }
+
+       syntax_size = strlen(S_OR(acf->syntax, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
+       syntax = ast_malloc(syntax_size);
+       if (!syntax) {
+               ast_cli(a->fd, "Memory allocation failure!\n");
+
+               return CLI_FAILURE;
+       }
+
+       snprintf(info, sizeof(info), "\n  -= Info about function '%s' =- \n\n", acf->name);
+       term_color(infotitle, info, COLOR_MAGENTA, 0, sizeof(infotitle));
+       term_color(syntitle, "[Synopsis]\n", COLOR_MAGENTA, 0, 40);
+       term_color(destitle, "[Description]\n", COLOR_MAGENTA, 0, 40);
+       term_color(stxtitle, "[Syntax]\n", COLOR_MAGENTA, 0, 40);
+       term_color(argtitle, "[Arguments]\n", COLOR_MAGENTA, 0, 40);
+       term_color(seealsotitle, "[See Also]\n", COLOR_MAGENTA, 0, 40);
+       term_color(syntax, S_OR(acf->syntax, "Not available"), COLOR_CYAN, 0, syntax_size);
+#ifdef AST_XML_DOCS
+       if (acf->docsrc == AST_XML_DOC) {
+               arguments = ast_xmldoc_printable(S_OR(acf->arguments, "Not available"), 1);
+               synopsis = ast_xmldoc_printable(S_OR(acf->synopsis, "Not available"), 1);
+               description = ast_xmldoc_printable(S_OR(acf->desc, "Not available"), 1);
+               seealso = ast_xmldoc_printable(S_OR(acf->seealso, "Not available"), 1);
+       } else
+#endif
+       {
+               synopsis_size = strlen(S_OR(acf->synopsis, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
+               synopsis = ast_malloc(synopsis_size);
+
+               description_size = strlen(S_OR(acf->desc, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
+               description = ast_malloc(description_size);
+
+               arguments_size = strlen(S_OR(acf->arguments, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
+               arguments = ast_malloc(arguments_size);
+
+               seealso_size = strlen(S_OR(acf->seealso, "Not Available")) + AST_TERM_MAX_ESCAPE_CHARS;
+               seealso = ast_malloc(seealso_size);
+
+               /* check allocated memory. */
+               if (!synopsis || !description || !arguments || !seealso) {
+                       ast_free(synopsis);
+                       ast_free(description);
+                       ast_free(arguments);
+                       ast_free(seealso);
+                       ast_free(syntax);
+
+                       return CLI_FAILURE;
+               }
+
+               term_color(arguments, S_OR(acf->arguments, "Not available"), COLOR_CYAN, 0, arguments_size);
+               term_color(synopsis, S_OR(acf->synopsis, "Not available"), COLOR_CYAN, 0, synopsis_size);
+               term_color(description, S_OR(acf->desc, "Not available"), COLOR_CYAN, 0, description_size);
+               term_color(seealso, S_OR(acf->seealso, "Not available"), COLOR_CYAN, 0, seealso_size);
+       }
+
+       ast_cli(a->fd, "%s%s%s\n\n%s%s\n\n%s%s\n\n%s%s\n\n%s%s\n",
+                       infotitle, syntitle, synopsis, destitle, description,
+                       stxtitle, syntax, argtitle, arguments, seealsotitle, seealso);
+
+       ast_free(arguments);
+       ast_free(synopsis);
+       ast_free(description);
+       ast_free(seealso);
+       ast_free(syntax);
+
+       return CLI_SUCCESS;
+}
+
+static struct ast_custom_function *ast_custom_function_find_nolock(const char *name)
+{
+       struct ast_custom_function *cur;
+       int cmp;
+
+       AST_RWLIST_TRAVERSE(&acf_root, cur, acflist) {
+               cmp = strcmp(name, cur->name);
+               if (cmp > 0) {
+                       continue;
+               }
+               if (!cmp) {
+                       /* Found it. */
+                       break;
+               }
+               /* Not in container. */
+               cur = NULL;
+               break;
+       }
+
+       return cur;
+}
+
+struct ast_custom_function *ast_custom_function_find(const char *name)
+{
+       struct ast_custom_function *acf;
+
+       AST_RWLIST_RDLOCK(&acf_root);
+       acf = ast_custom_function_find_nolock(name);
+       AST_RWLIST_UNLOCK(&acf_root);
+
+       return acf;
+}
+
+int ast_custom_function_unregister(struct ast_custom_function *acf)
+{
+       struct ast_custom_function *cur;
+
+       if (!acf) {
+               return -1;
+       }
+
+       AST_RWLIST_WRLOCK(&acf_root);
+       cur = AST_RWLIST_REMOVE(&acf_root, acf, acflist);
+       if (cur) {
+#ifdef AST_XML_DOCS
+               if (cur->docsrc == AST_XML_DOC) {
+                       ast_string_field_free_memory(acf);
+               }
+#endif
+               ast_verb(2, "Unregistered custom function %s\n", cur->name);
+       }
+       AST_RWLIST_UNLOCK(&acf_root);
+
+       return cur ? 0 : -1;
+}
+
+/*!
+ * \brief Returns true if given custom function escalates privileges on read.
+ *
+ * \param acf Custom function to query.
+ * \return True (non-zero) if reads escalate privileges.
+ * \return False (zero) if reads just read.
+ */
+static int read_escalates(const struct ast_custom_function *acf) {
+       return acf->read_escalates;
+}
+
+/*!
+ * \brief Returns true if given custom function escalates privileges on write.
+ *
+ * \param acf Custom function to query.
+ * \return True (non-zero) if writes escalate privileges.
+ * \return False (zero) if writes just write.
+ */
+static int write_escalates(const struct ast_custom_function *acf) {
+       return acf->write_escalates;
+}
+
+/*! \internal
+ *  \brief Retrieve the XML documentation of a specified ast_custom_function,
+ *         and populate ast_custom_function string fields.
+ *  \param acf ast_custom_function structure with empty 'desc' and 'synopsis'
+ *             but with a function 'name'.
+ *  \retval -1 On error.
+ *  \retval 0 On succes.
+ */
+static int acf_retrieve_docs(struct ast_custom_function *acf)
+{
+#ifdef AST_XML_DOCS
+       char *tmpxml;
+
+       /* Let's try to find it in the Documentation XML */
+       if (!ast_strlen_zero(acf->desc) || !ast_strlen_zero(acf->synopsis)) {
+               return 0;
+       }
+
+       if (ast_string_field_init(acf, 128)) {
+               return -1;
+       }
+
+       /* load synopsis */
+       tmpxml = ast_xmldoc_build_synopsis("function", acf->name, ast_module_name(acf->mod));
+       ast_string_field_set(acf, synopsis, tmpxml);
+       ast_free(tmpxml);
+
+       /* load description */
+       tmpxml = ast_xmldoc_build_description("function", acf->name, ast_module_name(acf->mod));
+       ast_string_field_set(acf, desc, tmpxml);
+       ast_free(tmpxml);
+
+       /* load syntax */
+       tmpxml = ast_xmldoc_build_syntax("function", acf->name, ast_module_name(acf->mod));
+       ast_string_field_set(acf, syntax, tmpxml);
+       ast_free(tmpxml);
+
+       /* load arguments */
+       tmpxml = ast_xmldoc_build_arguments("function", acf->name, ast_module_name(acf->mod));
+       ast_string_field_set(acf, arguments, tmpxml);
+       ast_free(tmpxml);
+
+       /* load seealso */
+       tmpxml = ast_xmldoc_build_seealso("function", acf->name, ast_module_name(acf->mod));
+       ast_string_field_set(acf, seealso, tmpxml);
+       ast_free(tmpxml);
+
+       acf->docsrc = AST_XML_DOC;
+#endif
+
+       return 0;
+}
+
+int __ast_custom_function_register(struct ast_custom_function *acf, struct ast_module *mod)
+{
+       struct ast_custom_function *cur;
+
+       if (!acf) {
+               return -1;
+       }
+
+       acf->mod = mod;
+#ifdef AST_XML_DOCS
+       acf->docsrc = AST_STATIC_DOC;
+#endif
+
+       if (acf_retrieve_docs(acf)) {
+               return -1;
+       }
+
+       AST_RWLIST_WRLOCK(&acf_root);
+
+       cur = ast_custom_function_find_nolock(acf->name);
+       if (cur) {
+               ast_log(LOG_ERROR, "Function %s already registered.\n", acf->name);
+               AST_RWLIST_UNLOCK(&acf_root);
+               return -1;
+       }
+
+       /* Store in alphabetical order */
+       AST_RWLIST_TRAVERSE_SAFE_BEGIN(&acf_root, cur, acflist) {
+               if (strcmp(acf->name, cur->name) < 0) {
+                       AST_RWLIST_INSERT_BEFORE_CURRENT(acf, acflist);
+                       break;
+               }
+       }
+       AST_RWLIST_TRAVERSE_SAFE_END;
+       if (!cur) {
+               AST_RWLIST_INSERT_TAIL(&acf_root, acf, acflist);
+       }
+
+       AST_RWLIST_UNLOCK(&acf_root);
+
+       ast_verb(2, "Registered custom function '" COLORIZE_FMT "'\n", COLORIZE(COLOR_BRCYAN, 0, acf->name));
+
+       return 0;
+}
+
+int __ast_custom_function_register_escalating(struct ast_custom_function *acf, enum ast_custom_function_escalation escalation, struct ast_module *mod)
+{
+       int res;
+
+       res = __ast_custom_function_register(acf, mod);
+       if (res != 0) {
+               return -1;
+       }
+
+       switch (escalation) {
+       case AST_CFE_NONE:
+               break;
+       case AST_CFE_READ:
+               acf->read_escalates = 1;
+               break;
+       case AST_CFE_WRITE:
+               acf->write_escalates = 1;
+               break;
+       case AST_CFE_BOTH:
+               acf->read_escalates = 1;
+               acf->write_escalates = 1;
+               break;
+       }
+
+       return 0;
+}
+
+/*! \brief return a pointer to the arguments of the function,
+ * and terminates the function name with '\\0'
+ */
+static char *func_args(char *function)
+{
+       char *args = strchr(function, '(');
+
+       if (!args) {
+               ast_log(LOG_WARNING, "Function '%s' doesn't contain parentheses.  Assuming null argument.\n", function);
+       } else {
+               char *p;
+               *args++ = '\0';
+               if ((p = strrchr(args, ')'))) {
+                       *p = '\0';
+               } else {
+                       ast_log(LOG_WARNING, "Can't find trailing parenthesis for function '%s(%s'?\n", function, args);
+               }
+       }
+       return args;
+}
+
+void pbx_live_dangerously(int new_live_dangerously)
+{
+       if (new_live_dangerously && !live_dangerously) {
+               ast_log(LOG_WARNING, "Privilege escalation protection disabled!\n"
+                       "See https://wiki.asterisk.org/wiki/x/1gKfAQ for more details.\n");
+       }
+
+       if (!new_live_dangerously && live_dangerously) {
+               ast_log(LOG_NOTICE, "Privilege escalation protection enabled.\n");
+       }
+       live_dangerously = new_live_dangerously;
+}
+
+int ast_thread_inhibit_escalations(void)
+{
+       int *thread_inhibit_escalations;
+
+       thread_inhibit_escalations = ast_threadstorage_get(
+               &thread_inhibit_escalations_tl, sizeof(*thread_inhibit_escalations));
+
+       if (thread_inhibit_escalations == NULL) {
+               ast_log(LOG_ERROR, "Error inhibiting privilege escalations for current thread\n");
+               return -1;
+       }
+
+       *thread_inhibit_escalations = 1;
+       return 0;
+}
+
+/*!
+ * \brief Indicates whether the current thread inhibits the execution of
+ * dangerous functions.
+ *
+ * \return True (non-zero) if dangerous function execution is inhibited.
+ * \return False (zero) if dangerous function execution is allowed.
+ */
+static int thread_inhibits_escalations(void)
+{
+       int *thread_inhibit_escalations;
+
+       thread_inhibit_escalations = ast_threadstorage_get(
+               &thread_inhibit_escalations_tl, sizeof(*thread_inhibit_escalations));
+
+       if (thread_inhibit_escalations == NULL) {
+               ast_log(LOG_ERROR, "Error checking thread's ability to run dangerous functions\n");
+               /* On error, assume that we are inhibiting */
+               return 1;
+       }
+
+       return *thread_inhibit_escalations;
+}
+
+/*!
+ * \brief Determines whether execution of a custom function's read function
+ * is allowed.
+ *
+ * \param acfptr Custom function to check
+ * \return True (non-zero) if reading is allowed.
+ * \return False (zero) if reading is not allowed.
+ */
+static int is_read_allowed(struct ast_custom_function *acfptr)
+{
+       if (!acfptr) {
+               return 1;
+       }
+
+       if (!read_escalates(acfptr)) {
+               return 1;
+       }
+
+       if (!thread_inhibits_escalations()) {
+               return 1;
+       }
+
+       if (live_dangerously) {
+               /* Global setting overrides the thread's preference */
+               ast_debug(2, "Reading %s from a dangerous context\n",
+                       acfptr->name);
+               return 1;
+       }
+
+       /* We have no reason to allow this function to execute */
+       return 0;
+}
+
+/*!
+ * \brief Determines whether execution of a custom function's write function
+ * is allowed.
+ *
+ * \param acfptr Custom function to check
+ * \return True (non-zero) if writing is allowed.
+ * \return False (zero) if writing is not allowed.
+ */
+static int is_write_allowed(struct ast_custom_function *acfptr)
+{
+       if (!acfptr) {
+               return 1;
+       }
+
+       if (!write_escalates(acfptr)) {
+               return 1;
+       }
+
+       if (!thread_inhibits_escalations()) {
+               return 1;
+       }
+
+       if (live_dangerously) {
+               /* Global setting overrides the thread's preference */
+               ast_debug(2, "Writing %s from a dangerous context\n",
+                       acfptr->name);
+               return 1;
+       }
+
+       /* We have no reason to allow this function to execute */
+       return 0;
+}
+
+int ast_func_read(struct ast_channel *chan, const char *function, char *workspace, size_t len)
+{
+       char *copy = ast_strdupa(function);
+       char *args = func_args(copy);
+       struct ast_custom_function *acfptr = ast_custom_function_find(copy);
+       int res;
+       struct ast_module_user *u = NULL;
+
+       if (acfptr == NULL) {
+               ast_log(LOG_ERROR, "Function %s not registered\n", copy);
+       } else if (!acfptr->read && !acfptr->read2) {
+               ast_log(LOG_ERROR, "Function %s cannot be read\n", copy);
+       } else if (!is_read_allowed(acfptr)) {
+               ast_log(LOG_ERROR, "Dangerous function %s read blocked\n", copy);
+       } else if (acfptr->read) {
+               if (acfptr->mod) {
+                       u = __ast_module_user_add(acfptr->mod, chan);
+               }
+               res = acfptr->read(chan, copy, args, workspace, len);
+               if (acfptr->mod && u) {
+                       __ast_module_user_remove(acfptr->mod, u);
+               }
+
+               return res;
+       } else {
+               struct ast_str *str = ast_str_create(16);
+
+               if (acfptr->mod) {
+                       u = __ast_module_user_add(acfptr->mod, chan);
+               }
+               res = acfptr->read2(chan, copy, args, &str, 0);
+               if (acfptr->mod && u) {
+                       __ast_module_user_remove(acfptr->mod, u);
+               }
+               ast_copy_string(workspace, ast_str_buffer(str), len > ast_str_size(str) ? ast_str_size(str) : len);
+               ast_free(str);
+
+               return res;
+       }
+
+       return -1;
+}
+
+int ast_func_read2(struct ast_channel *chan, const char *function, struct ast_str **str, ssize_t maxlen)
+{
+       char *copy = ast_strdupa(function);
+       char *args = func_args(copy);
+       struct ast_custom_function *acfptr = ast_custom_function_find(copy);
+       int res;
+       struct ast_module_user *u = NULL;
+
+       if (acfptr == NULL) {
+               ast_log(LOG_ERROR, "Function %s not registered\n", copy);
+       } else if (!acfptr->read && !acfptr->read2) {
+               ast_log(LOG_ERROR, "Function %s cannot be read\n", copy);
+       } else if (!is_read_allowed(acfptr)) {
+               ast_log(LOG_ERROR, "Dangerous function %s read blocked\n", copy);
+       } else {
+               if (acfptr->mod) {
+                       u = __ast_module_user_add(acfptr->mod, chan);
+               }
+               ast_str_reset(*str);
+               if (acfptr->read2) {
+                       /* ast_str enabled */
+                       res = acfptr->read2(chan, copy, args, str, maxlen);
+               } else {
+                       /* Legacy function pointer, allocate buffer for result */
+                       int maxsize = ast_str_size(*str);
+
+                       if (maxlen > -1) {
+                               if (maxlen == 0) {
+                                       if (acfptr->read_max) {
+                                               maxsize = acfptr->read_max;
+                                       } else {
+                                               maxsize = VAR_BUF_SIZE;
+                                       }
+                               } else {
+                                       maxsize = maxlen;
+                               }
+                               ast_str_make_space(str, maxsize);
+                       }
+                       res = acfptr->read(chan, copy, args, ast_str_buffer(*str), maxsize);
+               }
+               if (acfptr->mod && u) {
+                       __ast_module_user_remove(acfptr->mod, u);
+               }
+
+               return res;
+       }
+
+       return -1;
+}
+
+int ast_func_write(struct ast_channel *chan, const char *function, const char *value)
+{
+       char *copy = ast_strdupa(function);
+       char *args = func_args(copy);
+       struct ast_custom_function *acfptr = ast_custom_function_find(copy);
+
+       if (acfptr == NULL) {
+               ast_log(LOG_ERROR, "Function %s not registered\n", copy);
+       } else if (!acfptr->write) {
+               ast_log(LOG_ERROR, "Function %s cannot be written to\n", copy);
+       } else if (!is_write_allowed(acfptr)) {
+               ast_log(LOG_ERROR, "Dangerous function %s write blocked\n", copy);
+       } else {
+               int res;
+               struct ast_module_user *u = NULL;
+
+               if (acfptr->mod) {
+                       u = __ast_module_user_add(acfptr->mod, chan);
+               }
+               res = acfptr->write(chan, copy, args, value);
+               if (acfptr->mod && u) {
+                       __ast_module_user_remove(acfptr->mod, u);
+               }
+
+               return res;
+       }
+
+       return -1;
+}
+
+static struct ast_cli_entry acf_cli[] = {
+       AST_CLI_DEFINE(handle_show_functions, "Shows registered dialplan functions"),
+       AST_CLI_DEFINE(handle_show_function, "Describe a specific dialplan function"),
+};
+
+static void unload_pbx_functions_cli(void)
+{
+       ast_cli_unregister_multiple(acf_cli, ARRAY_LEN(acf_cli));
+}
+
+int load_pbx_functions_cli(void)
+{
+       ast_cli_register_multiple(acf_cli, ARRAY_LEN(acf_cli));
+       ast_register_cleanup(unload_pbx_functions_cli);
+
+       return 0;
+}