Thu Oct 9 06:44:55 2008

Asterisk developer's documentation

---

loader.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.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 Module Loader
 * 
 */

#include <stdio.h>
#include <dirent.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 61704 $")

#include "asterisk/module.h"
#include "asterisk/options.h"
#include "asterisk/config.h"
#include "asterisk/logger.h"
#include "asterisk/channel.h"
#include "asterisk/term.h"
#include "asterisk/manager.h"
#include "asterisk/cdr.h"
#include "asterisk/enum.h"
#include "asterisk/rtp.h"
#include "asterisk/lock.h"
#ifdef DLFCNCOMPAT
#include "asterisk/dlfcn-compat.h"
#else
#include <dlfcn.h>
#endif
#include "asterisk/md5.h"

#ifndef RTLD_NOW
#define RTLD_NOW 0
#endif

AST_MUTEX_DEFINE_STATIC(modlock);
AST_MUTEX_DEFINE_STATIC(reloadlock);

static struct module *module_list=NULL;
static int modlistver = 0;

static unsigned char expected_key[] =
{ 0x8e, 0x93, 0x22, 0x83, 0xf5, 0xc3, 0xc0, 0x75,
  0xff, 0x8b, 0xa9, 0xbe, 0x7c, 0x43, 0x74, 0x63 };

struct module {
   int (*load_module)(void);
   int (*unload_module)(void);
   int (*usecount)(void);
   char *(*description)(void);
   char *(*key)(void);
   int (*reload)(void);
   void *lib;
   char resource[256];
   struct module *next;
};

static struct loadupdate {
   int (*updater)(void);
   struct loadupdate *next;
} *updaters = NULL;

static int printdigest(unsigned char *d)
{
   int x;
   char buf[256];
   char buf2[16];
   snprintf(buf, sizeof(buf), "Unexpected signature:");
   for (x=0; x<16; x++) {
      snprintf(buf2, sizeof(buf2), " %02x", *(d++));
      strcat(buf, buf2);
   }
   strcat(buf, "\n");
   ast_log(LOG_DEBUG, "%s", buf);
   return 0;
}

static int key_matches(unsigned char *key1, unsigned char *key2)
{
   int match = 1;
   int x;
   for (x=0; x<16; x++) {
      match &= (key1[x] == key2[x]);
   }
   return match;
}

static int verify_key(unsigned char *key)
{
   struct MD5Context c;
   unsigned char digest[16];
   MD5Init(&c);
   MD5Update(&c, key, strlen((char *)key));
   MD5Final(digest, &c);
   if (key_matches(expected_key, digest))
      return 0;
   printdigest(digest);
   return -1;
}

int ast_unload_resource(const char *resource_name, int force)
{
   struct module *m, *ml = NULL;
   int res = -1;
   if (ast_mutex_lock(&modlock))
      ast_log(LOG_WARNING, "Failed to lock\n");
   m = module_list;
   while(m) {
      if (!strcasecmp(m->resource, resource_name)) {
         if ((res = m->usecount()) > 0)  {
            if (force) 
               ast_log(LOG_WARNING, "Warning:  Forcing removal of module %s with use count %d\n", resource_name, res);
            else {
               ast_log(LOG_WARNING, "Soft unload failed, '%s' has use count %d\n", resource_name, res);
               ast_mutex_unlock(&modlock);
               return -1;
            }
         }
         res = m->unload_module();
         if (res) {
            ast_log(LOG_WARNING, "Firm unload failed for %s\n", resource_name);
            if (force <= AST_FORCE_FIRM) {
               ast_mutex_unlock(&modlock);
               return -1;
            } else
               ast_log(LOG_WARNING, "** Dangerous **: Unloading resource anyway, at user request\n");
         }
         if (ml)
            ml->next = m->next;
         else
            module_list = m->next;
         dlclose(m->lib);
         free(m);
         break;
      }
      ml = m;
      m = m->next;
   }
   modlistver = rand();
   ast_mutex_unlock(&modlock);
   ast_update_use_count();
   return res;
}

char *ast_module_helper(char *line, char *word, int pos, int state, int rpos, int needsreload)
{
   struct module *m;
   int which=0;
   char *ret;

   if (pos != rpos)
      return NULL;
   ast_mutex_lock(&modlock);
   m = module_list;
   while(m) {
      if (!strncasecmp(word, m->resource, strlen(word)) && (m->reload || !needsreload)) {
         if (++which > state)
            break;
      }
      m = m->next;
   }
   if (m) {
      ret = strdup(m->resource);
   } else {
      ret = NULL;
      if (!strncasecmp(word, "extconfig", strlen(word))) {
         if (++which > state)
            ret = strdup("extconfig");
      } else if (!strncasecmp(word, "manager", strlen(word))) {
         if (++which > state)
            ret = strdup("manager");
      } else if (!strncasecmp(word, "enum", strlen(word))) {
         if (++which > state)
            ret = strdup("enum");
      } else if (!strncasecmp(word, "rtp", strlen(word))) {
         if (++which > state)
            ret = strdup("rtp");
      }
         
   }
   ast_mutex_unlock(&modlock);
   return ret;
}

int ast_module_reload(const char *name)
{
   struct module *m;
   int reloaded = 0;
   int oldversion;
   int (*reload)(void);
   /* We'll do the logger and manager the favor of calling its reload here first */

   if (ast_mutex_trylock(&reloadlock)) {
      ast_verbose("The previous reload command didn't finish yet\n");
      return -1;
   }
   time(&ast_lastreloadtime);

   if (!name || !strcasecmp(name, "extconfig")) {
      read_config_maps();
      reloaded = 2;
   }
   if (!name || !strcasecmp(name, "manager")) {
      reload_manager();
      reloaded = 2;
   }
   if (!name || !strcasecmp(name, "cdr")) {
      ast_cdr_engine_reload();
      reloaded = 2;
   }
   if (!name || !strcasecmp(name, "enum")) {
      ast_enum_reload();
      reloaded = 2;
   }
   if (!name || !strcasecmp(name, "rtp")) {
      ast_rtp_reload();
      reloaded = 2;
   }
   if (!name || !strcasecmp(name, "dnsmgr")) {
      dnsmgr_reload();
      reloaded = 2;
   }

   ast_mutex_lock(&modlock);
   oldversion = modlistver;
   m = module_list;
   while(m) {
      if (!name || !strcasecmp(name, m->resource)) {
         if (reloaded < 1)
            reloaded = 1;
         reload = m->reload;
         ast_mutex_unlock(&modlock);
         if (reload) {
            reloaded = 2;
            if (option_verbose > 2) 
               ast_verbose(VERBOSE_PREFIX_3 "Reloading module '%s' (%s)\n", m->resource, m->description());
            reload();
         }
         ast_mutex_lock(&modlock);
         if (oldversion != modlistver)
            break;
      }
      m = m->next;
   }
   ast_mutex_unlock(&modlock);
   ast_mutex_unlock(&reloadlock);
   return reloaded;
}

static int __load_resource(const char *resource_name, const struct ast_config *cfg)
{
   static char fn[256];
   int errors=0;
   int res;
   struct module *m;
   int flags=RTLD_NOW;
#ifdef RTLD_GLOBAL
   char *val;
#endif
   unsigned char *key;
   char tmp[80];

   if (strncasecmp(resource_name, "res_", 4)) {
#ifdef RTLD_GLOBAL
      if (cfg) {
         if ((val = ast_variable_retrieve(cfg, "global", resource_name))
               && ast_true(val))
            flags |= RTLD_GLOBAL;
      }
#endif
   } else {
      /* Resource modules are always loaded global and lazy */
#ifdef RTLD_GLOBAL
      flags = (RTLD_GLOBAL | RTLD_LAZY);
#else
      flags = RTLD_LAZY;
#endif
   }
   
   if (ast_mutex_lock(&modlock))
      ast_log(LOG_WARNING, "Failed to lock\n");
   m = module_list;
   while(m) {
      if (!strcasecmp(m->resource, resource_name)) {
         ast_log(LOG_WARNING, "Module '%s' already exists\n", resource_name);
         ast_mutex_unlock(&modlock);
         return -1;
      }
      m = m->next;
   }
   m = malloc(sizeof(struct module));  
   if (!m) {
      ast_log(LOG_WARNING, "Out of memory\n");
      ast_mutex_unlock(&modlock);
      return -1;
   }
   strncpy(m->resource, resource_name, sizeof(m->resource)-1);
   if (resource_name[0] == '/') {
      strncpy(fn, resource_name, sizeof(fn)-1);
   } else {
      snprintf(fn, sizeof(fn), "%s/%s", (char *)ast_config_AST_MODULE_DIR, resource_name);
   }
   m->lib = dlopen(fn, flags);
   if (!m->lib) {
      ast_log(LOG_WARNING, "%s\n", dlerror());
      free(m);
      ast_mutex_unlock(&modlock);
      return -1;
   }
   m->load_module = dlsym(m->lib, "load_module");
   if (m->load_module == NULL)
      m->load_module = dlsym(m->lib, "_load_module");
   if (!m->load_module) {
      ast_log(LOG_WARNING, "No load_module in module %s\n", fn);
      errors++;
   }
   m->unload_module = dlsym(m->lib, "unload_module");
   if (m->unload_module == NULL)
      m->unload_module = dlsym(m->lib, "_unload_module");
   if (!m->unload_module) {
      ast_log(LOG_WARNING, "No unload_module in module %s\n", fn);
      errors++;
   }
   m->usecount = dlsym(m->lib, "usecount");
   if (m->usecount == NULL)
      m->usecount = dlsym(m->lib, "_usecount");
   if (!m->usecount) {
      ast_log(LOG_WARNING, "No usecount in module %s\n", fn);
      errors++;
   }
   m->description = dlsym(m->lib, "description");
   if (m->description == NULL)
      m->description = dlsym(m->lib, "_description");
   if (!m->description) {
      ast_log(LOG_WARNING, "No description in module %s\n", fn);
      errors++;
   }
   m->key = dlsym(m->lib, "key");
   if (m->key == NULL)
      m->key = dlsym(m->lib, "_key");
   if (!m->key) {
      ast_log(LOG_WARNING, "No key routine in module %s\n", fn);
      errors++;
   }

   m->reload = dlsym(m->lib, "reload");
   if (m->reload == NULL)
      m->reload = dlsym(m->lib, "_reload");

   if (!m->key || !(key = (unsigned char *) m->key())) {
      ast_log(LOG_WARNING, "Key routine returned NULL in module %s\n", fn);
      key = NULL;
      errors++;
   }
   if (key && verify_key(key)) {
      ast_log(LOG_WARNING, "Unexpected key returned by module %s\n", fn);
      errors++;
   }
   if (errors) {
      ast_log(LOG_WARNING, "%d error%s loading module %s, aborted\n", errors, (errors != 1) ? "s" : "", fn);
      dlclose(m->lib);
      free(m);
      ast_mutex_unlock(&modlock);
      return -1;
   }
   if (!fully_booted) {
      if (option_verbose) 
         ast_verbose( " => (%s)\n", term_color(tmp, m->description(), COLOR_BROWN, COLOR_BLACK, sizeof(tmp)));
      if (option_console && !option_verbose)
         ast_verbose( ".");
   } else {
      if (option_verbose)
         ast_verbose(VERBOSE_PREFIX_1 "Loaded %s => (%s)\n", fn, m->description());
   }

   /* add module 'm' to end of module_list chain
      so reload commands will be issued in same order modules were loaded */
   m->next = NULL;
   if (module_list == NULL) {
      /* empty list so far, add at front */
      module_list = m;
   }
   else {
      struct module *i;
      /* find end of chain, and add there */
      for (i = module_list; i->next; i = i->next)
         ;
      i->next = m;
   }
   
   modlistver = rand();
   ast_mutex_unlock(&modlock);
   if ((res = m->load_module())) {
      ast_log(LOG_WARNING, "%s: load_module failed, returning %d\n", m->resource, res);
      ast_unload_resource(resource_name, 0);
      return -1;
   }
   ast_update_use_count();
   return 0;
}

int ast_load_resource(const char *resource_name)
{
   int o;
   struct ast_config *cfg = NULL;
   int res;

   /* Keep the module file parsing silent */
   o = option_verbose;
   option_verbose = 0;
   cfg = ast_config_load(AST_MODULE_CONFIG);
   option_verbose = o;
   res = __load_resource(resource_name, cfg);
   if (cfg)
      ast_config_destroy(cfg);
   return res;
}  

static int ast_resource_exists(char *resource)
{
   struct module *m;
   if (ast_mutex_lock(&modlock))
      ast_log(LOG_WARNING, "Failed to lock\n");
   m = module_list;
   while(m) {
      if (!strcasecmp(resource, m->resource))
         break;
      m = m->next;
   }
   ast_mutex_unlock(&modlock);
   if (m)
      return -1;
   else
      return 0;
}

static const char *loadorder[] =
{
   "res_",
   "pbx_",
   "chan_",
   NULL,
};

int load_modules(const int preload_only)
{
   struct ast_config *cfg;
   struct ast_variable *v;
   char tmp[80];

   if (option_verbose) {
      if (preload_only)
         ast_verbose("Asterisk Dynamic Loader loading preload modules:\n");
      else
         ast_verbose("Asterisk Dynamic Loader Starting:\n");
   }

   cfg = ast_config_load(AST_MODULE_CONFIG);
   if (cfg) {
      int doload;

      /* Load explicitly defined modules */
      for (v = ast_variable_browse(cfg, "modules"); v; v = v->next) {
         doload = 0;

         if (preload_only)
            doload = !strcasecmp(v->name, "preload");
         else
            doload = !strcasecmp(v->name, "load");

             if (doload) {
            if (option_debug && !option_verbose)
               ast_log(LOG_DEBUG, "Loading module %s\n", v->value);
            if (option_verbose) {
               ast_verbose(VERBOSE_PREFIX_1 "[%s]", term_color(tmp, v->value, COLOR_BRWHITE, 0, sizeof(tmp)));
               fflush(stdout);
            }
            if (__load_resource(v->value, cfg)) {
               ast_log(LOG_WARNING, "Loading module %s failed!\n", v->value);
               ast_config_destroy(cfg);
               return -1;
            }
         }
      }
   }

   if (preload_only) {
      ast_config_destroy(cfg);
      return 0;
   }

   if (!cfg || ast_true(ast_variable_retrieve(cfg, "modules", "autoload"))) {
      /* Load all modules */
      DIR *mods;
      struct dirent *d;
      int x;

      /* Loop through each order */
      for (x=0; x<sizeof(loadorder) / sizeof(loadorder[0]); x++) {
         mods = opendir((char *)ast_config_AST_MODULE_DIR);
         if (mods) {
            while((d = readdir(mods))) {
               /* Must end in .so to load it.  */
               if ((strlen(d->d_name) > 3) && 
                   (!loadorder[x] || !strncasecmp(d->d_name, loadorder[x], strlen(loadorder[x]))) && 
                   !strcasecmp(d->d_name + strlen(d->d_name) - 3, ".so") &&
                  !ast_resource_exists(d->d_name)) {
                  /* It's a shared library -- Just be sure we're allowed to load it -- kinda
                     an inefficient way to do it, but oh well. */
                  if (cfg) {
                     v = ast_variable_browse(cfg, "modules");
                     while(v) {
                        if (!strcasecmp(v->name, "noload") &&
                            !strcasecmp(v->value, d->d_name)) 
                           break;
                        v = v->next;
                     }
                     if (v) {
                        if (option_verbose) {
                           ast_verbose( VERBOSE_PREFIX_1 "[skipping %s]\n", d->d_name);
                           fflush(stdout);
                        }
                        continue;
                     }
                     
                  }
                  if (option_debug && !option_verbose)
                     ast_log(LOG_DEBUG, "Loading module %s\n", d->d_name);
                  if (option_verbose) {
                     ast_verbose( VERBOSE_PREFIX_1 "[%s]", term_color(tmp, d->d_name, COLOR_BRWHITE, 0, sizeof(tmp)));
                     fflush(stdout);
                  }
                  if (__load_resource(d->d_name, cfg)) {
                     ast_log(LOG_WARNING, "Loading module %s failed!\n", d->d_name);
                     if (cfg)
                        ast_config_destroy(cfg);
                     return -1;
                  }
               }
            }
            closedir(mods);
         } else {
            if (!option_quiet)
               ast_log(LOG_WARNING, "Unable to open modules directory %s.\n", (char *)ast_config_AST_MODULE_DIR);
         }
      }
   } 
   ast_config_destroy(cfg);
   return 0;
}

void ast_update_use_count(void)
{
   /* Notify any module monitors that the use count for a 
      resource has changed */
   struct loadupdate *m;
   if (ast_mutex_lock(&modlock))
      ast_log(LOG_WARNING, "Failed to lock\n");
   m = updaters;
   while(m) {
      m->updater();
      m = m->next;
   }
   ast_mutex_unlock(&modlock);
   
}

int ast_update_module_list(int (*modentry)(const char *module, const char *description, int usecnt, const char *like),
            const char *like)
{
   struct module *m;
   int unlock = -1;
   int total_mod_loaded = 0;

   if (ast_mutex_trylock(&modlock))
      unlock = 0;
   m = module_list;
   while (m) {
      total_mod_loaded += modentry(m->resource, m->description(), m->usecount(), like);
      m = m->next;
   }
   if (unlock)
      ast_mutex_unlock(&modlock);

   return total_mod_loaded;
}

int ast_loader_register(int (*v)(void)) 
{
   struct loadupdate *tmp;
   /* XXX Should be more flexible here, taking > 1 verboser XXX */
   if ((tmp = malloc(sizeof (struct loadupdate)))) {
      tmp->updater = v;
      if (ast_mutex_lock(&modlock))
         ast_log(LOG_WARNING, "Failed to lock\n");
      tmp->next = updaters;
      updaters = tmp;
      ast_mutex_unlock(&modlock);
      return 0;
   }
   return -1;
}

int ast_loader_unregister(int (*v)(void))
{
   int res = -1;
   struct loadupdate *tmp, *tmpl=NULL;
   if (ast_mutex_lock(&modlock))
      ast_log(LOG_WARNING, "Failed to lock\n");
   tmp = updaters;
   while(tmp) {
      if (tmp->updater == v)  {
         if (tmpl)
            tmpl->next = tmp->next;
         else
            updaters = tmp->next;
         break;
      }
      tmpl = tmp;
      tmp = tmp->next;
   }
   if (tmp)
      res = 0;
   ast_mutex_unlock(&modlock);
   return res;
}

---