conf/conf.c

   1 /*
   2  *      BIRD Internet Routing Daemon -- Configuration File Handling
   3  *
   4  *      (c) 1998--2000 Martin Mares <mj@ucw.cz>
   5  *
   6  *      Can be freely distributed and used under the terms of the GNU GPL.
   7  */
   8
   9 /**
  10  * DOC: Configuration manager
  11  *
  12  * Configuration of BIRD is complex, yet straightforward. There exist three
  13  * modules taking care of the configuration: config manager (which takes care
  14  * of storage of the config information and controls switching between configs),
  15  * lexical analyzer and parser.
  16  *
  17  * The configuration manager stores each config as a &config structure
  18  * accompanied by a linear pool from which all information associated
  19  * with the config and pointed to by the &config structure is allocated.
  20  *
  21  * There can exist up four different configurations at one time: an active
  22  * one (pointed to by @config), configuration we are just switching from
  23  * (@old_config), one queued for the next reconfiguration (@future_config;
  24  * if it's non-%NULL and the user wants to reconfigure once again, we just
  25  * free the previous queued config and replace it with the new one) and
  26  * finally a config being parsed (@new_config).
  27  *
  28  * Loading of new configuration is very simple: just call config_alloc()
  29  * to get a new &config structure, then use config_parse() to parse a
  30  * configuration file and fill all fields of the structure
  31  * and finally ask the config manager to switch to the new
  32  * config by calling config_commit().
  33  *
  34  * CLI commands are parsed in a very similar way -- there is also a stripped-down
  35  * &config structure associated with them and they are lex-ed and parsed by the
  36  * same functions, only a special fake token is prepended before the command
  37  * text to make the parser recognize only the rules corresponding to CLI commands.
  38  */
  39
  40 #include <setjmp.h>
  41 #include <stdarg.h>
  42
  43 #undef LOCAL_DEBUG
  44
  45 #include "nest/bird.h"
  46 #include "nest/route.h"
  47 #include "nest/protocol.h"
  48 #include "nest/iface.h"
  49 #include "lib/resource.h"
  50 #include "lib/string.h"
  51 #include "lib/event.h"
  52 #include "lib/timer.h"
  53 #include "conf/conf.h"
  54 #include "filter/filter.h"
  55
  56 static jmp_buf conf_jmpbuf;
  57
  58 struct config *config, *new_config, *old_config, *future_config;
  59 static event *config_event;
  60 int shutting_down;
  61 bird_clock_t boot_time;
  62
  63 /**
  64  * config_alloc - allocate a new configuration
  65  * @name: name of the config
  66  *
  67  * This function creates new &config structure, attaches a resource
  68  * pool and a linear memory pool to it and makes it available for
  69  * further use. Returns a pointer to the structure.
  70  */
  71 struct config *
  72 config_alloc(byte *name)
  73 {
  74   pool *p = rp_new(&root_pool, "Config");
  75   linpool *l = lp_new(p, 4080);
  76   struct config *c = lp_allocz(l, sizeof(struct config));
  77
  78   c->pool = p;
  79   cfg_mem = c->mem = l;
  80   c->file_name = cfg_strdup(name);
  81   c->load_time = now;
  82   if (!boot_time)
  83     boot_time = now;
  84   return c;
  85 }
  86
  87 /**
  88  * config_parse - parse a configuration
  89  * @c: configuration
  90  *
  91  * config_parse() reads input by calling a hook function pointed to
  92  * by @cf_read_hook and parses it according to the configuration
  93  * grammar. It also calls all the preconfig and postconfig hooks
  94  * before, resp. after parsing.
  95  *
  96  * Result: 1 if the config has been parsed successfully, 0 if any
  97  * error has occurred (such as anybody calling cf_error()) and
  98  * the @err_msg field has been set to the error message.
  99  */
 100 int
 101 config_parse(struct config *c)
 102 {
 103   DBG("Parsing configuration file `%s'\n", c->file_name);
 104   new_config = c;
 105   cfg_mem = c->mem;
 106   if (setjmp(conf_jmpbuf))
 107     return 0;
 108   cf_lex_init(0);
 109   sysdep_preconfig(c);
 110   protos_preconfig(c);
 111   rt_preconfig(c);
 112   cf_parse();
 113   protos_postconfig(c);
 114 #ifdef IPV6
 115   if (!c->router_id)
 116     cf_error("Router ID must be configured manually on IPv6 routers");
 117 #endif
 118   return 1;
 119 }
 120
 121 /**
 122  * cli_parse - parse a CLI command
 123  * @c: temporary config structure
 124  *
 125  * cli_parse() is similar to config_parse(), but instead of a configuration,
 126  * it parses a CLI command. See the CLI module for more information.
 127  */
 128 int
 129 cli_parse(struct config *c)
 130 {
 131   new_config = c;
 132   c->sym_fallback = config->sym_hash;
 133   cfg_mem = c->mem;
 134   if (setjmp(conf_jmpbuf))
 135     return 0;
 136   cf_lex_init(1);
 137   cf_parse();
 138   return 1;
 139 }
 140
 141 /**
 142  * config_free - free a configuration
 143  * @c: configuration to be freed
 144  *
 145  * This function takes a &config structure and frees all resources
 146  * associated with it.
 147  */
 148 void
 149 config_free(struct config *c)
 150 {
 151   rfree(c->pool);
 152 }
 153
 154 void
 155 config_add_obstacle(struct config *c)
 156 {
 157   DBG("+++ adding obstacle %d\n", c->obstacle_count);
 158   c->obstacle_count++;
 159 }
 160
 161 void
 162 config_del_obstacle(struct config *c)
 163 {
 164   DBG("+++ deleting obstacle %d\n", c->obstacle_count);
 165   c->obstacle_count--;
 166   if (!c->obstacle_count)
 167     {
 168       ASSERT(config_event);
 169       ev_schedule(config_event);
 170     }
 171 }
 172
 173 static int
 174 global_commit(struct config *new, struct config *old)
 175 {
 176   if (!old)
 177     return 0;
 178   if (!new->router_id)
 179     new->router_id = old->router_id;
 180   if (new->router_id != old->router_id)
 181     return 1;
 182   return 0;
 183 }
 184
 185 static int
 186 config_do_commit(struct config *c)
 187 {
 188   int force_restart, nobs;
 189
 190   DBG("do_commit\n");
 191   old_config = config;
 192   config = new_config = c;
 193   if (old_config)
 194     old_config->obstacle_count++;
 195   DBG("sysdep_commit\n");
 196   force_restart = sysdep_commit(c, old_config);
 197   DBG("global_commit\n");
 198   force_restart |= global_commit(c, old_config);
 199   DBG("rt_commit\n");
 200   rt_commit(c, old_config);
 201   DBG("protos_commit\n");
 202   protos_commit(c, old_config, force_restart);
 203   new_config = NULL;                    /* Just to be sure nobody uses that now */
 204   if (old_config)
 205     nobs = --old_config->obstacle_count;
 206   else
 207     nobs = 0;
 208   DBG("do_commit finished with %d obstacles remaining\n", nobs);
 209   return !nobs;
 210 }
 211
 212 static void
 213 config_done(void *unused)
 214 {
 215   struct config *c;
 216
 217   DBG("config_done\n");
 218   for(;;)
 219     {
 220       if (config->shutdown)
 221         sysdep_shutdown_done();
 222       log(L_INFO "Reconfigured");
 223       if (old_config)
 224         {
 225           config_free(old_config);
 226           old_config = NULL;
 227         }
 228       if (!future_config)
 229         break;
 230       c = future_config;
 231       future_config = NULL;
 232       log(L_INFO "Switching to queued configuration...");
 233       if (!config_do_commit(c))
 234         break;
 235     }
 236 }
 237
 238 /**
 239  * config_commit - commit a configuration
 240  * @c: new configuration
 241  *
 242  * When a configuration is parsed and prepared for use, the
 243  * config_commit() function starts the process of reconfiguration.
 244  * It checks whether there is already a reconfiguration in progress
 245  * in which case it just queues the new config for later processing.
 246  * Else it notifies all modules about the new configuration by calling
 247  * their commit() functions which can either accept it immediately
 248  * or call config_add_obstacle() to report that they need some time
 249  * to complete the reconfiguration. After all such obstacles are removed
 250  * using config_del_obstacle(), the old configuration is freed and
 251  * everything runs according to the new one.
 252  *
 253  * Result: %CONF_DONE if the configuration has been accepted immediately,
 254  * %CONF_PROGRESS if it will take some time to switch to it, %CONF_QUEUED
 255  * if it's been queued due to another reconfiguration being in progress now
 256  * or %CONF_SHUTDOWN if BIRD is in shutdown mode and no new configurations
 257  * are accepted.
 258  */
 259 int
 260 config_commit(struct config *c)
 261 {
 262   if (!config)                          /* First-time configuration */
 263     {
 264       config_do_commit(c);
 265       return CONF_DONE;
 266     }
 267   if (old_config)                       /* Reconfiguration already in progress */
 268     {
 269       if (shutting_down)
 270         {
 271           log(L_INFO "New configuration discarded due to shutdown");
 272           config_free(c);
 273           return CONF_SHUTDOWN;
 274         }
 275       if (future_config)
 276         {
 277           log(L_INFO "Queueing new configuration, ignoring the one already queued");
 278           config_free(future_config);
 279         }
 280       else
 281         log(L_INFO "Queued new configuration");
 282       future_config = c;
 283       return CONF_QUEUED;
 284     }
 285   if (config_do_commit(c))
 286     {
 287       config_done(NULL);
 288       return CONF_DONE;
 289     }
 290   if (!config_event)
 291     {
 292       config_event = ev_new(&root_pool);
 293       config_event->hook = config_done;
 294     }
 295   return CONF_PROGRESS;
 296 }
 297
 298 /**
 299  * order_shutdown - order BIRD shutdown
 300  *
 301  * This function initiates shutdown of BIRD. It's accomplished by asking
 302  * for switching to an empty configuration.
 303  */
 304 void
 305 order_shutdown(void)
 306 {
 307   struct config *c;
 308
 309   if (shutting_down)
 310     return;
 311   log(L_INFO "Shutting down");
 312   c = lp_alloc(config->mem, sizeof(struct config));
 313   memcpy(c, config, sizeof(struct config));
 314   init_list(&c->protos);
 315   init_list(&c->tables);
 316   c->shutdown = 1;
 317   config_commit(c);
 318   shutting_down = 1;
 319 }
 320
 321 /**
 322  * cf_error - report a configuration error
 323  * @msg: printf-like format string
 324  *
 325  * cf_error() can be called during execution of config_parse(), that is
 326  * from the parser, a preconfig hook or a postconfig hook, to report an
 327  * error in the configuration.
 328  */
 329 void
 330 cf_error(char *msg, ...)
 331 {
 332   char buf[1024];
 333   va_list args;
 334
 335   va_start(args, msg);
 336   if (bvsnprintf(buf, sizeof(buf), msg, args) < 0)
 337     strcpy(buf, "<bug: error message too long>");
 338   new_config->err_msg = cfg_strdup(buf);
 339   new_config->err_lino = conf_lino;
 340   longjmp(conf_jmpbuf, 1);
 341 }
 342
 343 /**
 344  * cfg_strdup - copy a string to config memory
 345  * @c: string to copy
 346  *
 347  * cfg_strdup() creates a new copy of the string in the memory
 348  * pool associated with the configuration being currently parsed.
 349  * It's often used when a string literal occurs in the configuration
 350  * and we want to preserve it for further use.
 351  */
 352 char *
 353 cfg_strdup(char *c)
 354 {
 355   int l = strlen(c) + 1;
 356   char *z = cfg_allocu(l);
 357   memcpy(z, c, l);
 358   return z;
 359 }