loader.c

Go to the documentation of this file.

/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * Module Loader
 * 
 * Copyright (C) 1999, Mark Spencer
 *
 * Mark Spencer <markster@linux-support.net>
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 */

#include <stdio.h>
#include <dirent.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#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/enum.h>
#include <asterisk/rtp.h>
#ifdef __APPLE__
#include <asterisk/dlfcn-compat.h>
#else
#include <dlfcn.h>
#endif
#include <asterisk/md5.h>
#include <pthread.h>
#include "asterisk.h"
#include "astconf.h"

#ifndef RTLD_NOW
#define RTLD_NOW 0
#endif

static 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 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, buf);
   return 0;
}

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

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

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

AST_MUTEX_DEFINE_STATIC(modlock);
AST_MUTEX_DEFINE_STATIC(reloadlock);

static struct module *module_list=NULL;

int ast_unload_resource(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;
   }
   ast_mutex_unlock(&modlock);
   ast_update_use_count();
   return res;
}

void ast_module_reload(void)
{
   struct module *m;

   /* 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;
   }
   reload_manager();
   ast_enum_reload();
   ast_rtp_reload();
   time(&ast_lastreloadtime);

   ast_mutex_lock(&modlock);
   m = module_list;
   while(m) {
      if (m->reload) {
         if (option_verbose > 2) 
            ast_verbose(VERBOSE_PREFIX_3 "Reloading module '%s' (%s)\n", m->resource, m->description());
         m->reload();
      }
      m = m->next;
   }
   ast_mutex_unlock(&modlock);
   ast_mutex_unlock(&reloadlock);
}

int ast_load_resource(char *resource_name)
{
   static char fn[256];
   int errors=0;
   int res;
   struct module *m;
   int flags=RTLD_NOW;
#ifdef RTLD_GLOBAL
   char *val;
#endif
   char *key;
   int o;
   struct ast_config *cfg;
   char tmp[80];
   /* Keep the module file parsing silent */
   o = option_verbose;
   if (strncasecmp(resource_name, "res_", 4)) {
      option_verbose = 0;
      cfg = ast_load(AST_MODULE_CONFIG);
      option_verbose = o;
      if (cfg) {
#ifdef RTLD_GLOBAL
         if ((val = ast_variable_retrieve(cfg, "global", resource_name))
               && ast_true(val))
            flags |= RTLD_GLOBAL;
#endif
         ast_destroy(cfg);
      }
   } 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 = 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, 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;
   }
   
   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;
}  

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;
}

int load_modules()
{
   struct ast_config *cfg;
   struct ast_variable *v;
   char tmp[80];
   if (option_verbose) 
      ast_verbose( "Asterisk Dynamic Loader Starting:\n");
   cfg = ast_load(AST_MODULE_CONFIG);
   if (cfg) {
      /* Load explicitly defined modules */
      v = ast_variable_browse(cfg, "modules");
      while(v) {
         if (!strcasecmp(v->name, "load")) {
            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 (ast_load_resource(v->value)) {
               ast_log(LOG_WARNING, "Loading module %s failed!\n", v->value);
               if (cfg)
                  ast_destroy(cfg);
               return -1;
            }
         }
         v=v->next;
      }
   }
   if (!cfg || ast_true(ast_variable_retrieve(cfg, "modules", "autoload"))) {
      /* Load all modules */
      DIR *mods;
      struct dirent *d;
      int x;
      /* Make two passes.  First, load any resource modules, then load the others. */
      for (x=0;x<2;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) && (x || !strncasecmp(d->d_name, "res_", 4)) && 
                   !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 (ast_load_resource(d->d_name)) {
                     ast_log(LOG_WARNING, "Loading module %s failed!\n", d->d_name);
                     if (cfg)
                        ast_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_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)(char *module, char *description, int usecnt))
{
   struct module *m;
   int unlock = -1;
   if (ast_mutex_trylock(&modlock))
      unlock = 0;
   m = module_list;
   while(m) {
      modentry(m->resource, m->description(), m->usecount());
      m = m->next;
   }
   if (unlock)
      ast_mutex_unlock(&modlock);
   return 0;
}

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;
}

---