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 are 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 to 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
 179   if (!ipa_equal(old->bind_bgp_addr, new->bind_bgp_addr) ||
 180       (old->bind_bgp_port != new->bind_bgp_port) ||
 181       (old->bind_bgp_flags != new->bind_bgp_flags))
 182     log(L_WARN "Reconfiguration of BGP listening socket not implemented, please restart BIRD.");
 183
 184   if (!new->router_id)
 185     new->router_id = old->router_id;
 186   if (new->router_id != old->router_id)
 187     return 1;
 188   return 0;
 189 }
 190
 191 static int
 192 config_do_commit(struct config *c)
 193 {
 194   int force_restart, nobs;
 195
 196   DBG("do_commit\n");
 197   old_config = config;
 198   config = new_config = c;
 199   if (old_config)
 200     old_config->obstacle_count++;
 201   DBG("sysdep_commit\n");
 202   force_restart = sysdep_commit(c, old_config);
 203   DBG("global_commit\n");
 204   force_restart |= global_commit(c, old_config);
 205   DBG("rt_commit\n");
 206   rt_commit(c, old_config);
 207   DBG("protos_commit\n");
 208   protos_commit(c, old_config, force_restart);
 209   new_config = NULL;                    /* Just to be sure nobody uses that now */
 210   if (old_config)
 211     nobs = --old_config->obstacle_count;
 212   else
 213     nobs = 0;
 214   DBG("do_commit finished with %d obstacles remaining\n", nobs);
 215   return !nobs;
 216 }
 217
 218 static void
 219 config_done(void *unused UNUSED)
 220 {
 221   struct config *c;
 222
 223   DBG("config_done\n");
 224   for(;;)
 225     {
 226       if (config->shutdown)
 227         sysdep_shutdown_done();
 228       log(L_INFO "Reconfigured");
 229       if (old_config)
 230         {
 231           config_free(old_config);
 232           old_config = NULL;
 233         }
 234       if (!future_config)
 235         break;
 236       c = future_config;
 237       future_config = NULL;
 238       log(L_INFO "Switching to queued configuration...");
 239       if (!config_do_commit(c))
 240         break;
 241     }
 242 }
 243
 244 /**
 245  * config_commit - commit a configuration
 246  * @c: new configuration
 247  *
 248  * When a configuration is parsed and prepared for use, the
 249  * config_commit() function starts the process of reconfiguration.
 250  * It checks whether there is already a reconfiguration in progress
 251  * in which case it just queues the new config for later processing.
 252  * Else it notifies all modules about the new configuration by calling
 253  * their commit() functions which can either accept it immediately
 254  * or call config_add_obstacle() to report that they need some time
 255  * to complete the reconfiguration. After all such obstacles are removed
 256  * using config_del_obstacle(), the old configuration is freed and
 257  * everything runs according to the new one.
 258  *
 259  * Result: %CONF_DONE if the configuration has been accepted immediately,
 260  * %CONF_PROGRESS if it will take some time to switch to it, %CONF_QUEUED
 261  * if it's been queued due to another reconfiguration being in progress now
 262  * or %CONF_SHUTDOWN if BIRD is in shutdown mode and no new configurations
 263  * are accepted.
 264  */
 265 int
 266 config_commit(struct config *c)
 267 {
 268   if (!config)                          /* First-time configuration */
 269     {
 270       config_do_commit(c);
 271       return CONF_DONE;
 272     }
 273   if (old_config)                       /* Reconfiguration already in progress */
 274     {
 275       if (shutting_down == 2)
 276         {
 277           log(L_INFO "New configuration discarded due to shutdown");
 278           config_free(c);
 279           return CONF_SHUTDOWN;
 280         }
 281       if (future_config)
 282         {
 283           log(L_INFO "Queueing new configuration, ignoring the one already queued");
 284           config_free(future_config);
 285         }
 286       else
 287         log(L_INFO "Queued new configuration");
 288       future_config = c;
 289       return CONF_QUEUED;
 290     }
 291   if (config_do_commit(c))
 292     {
 293       config_done(NULL);
 294       return CONF_DONE;
 295     }
 296   if (!config_event)
 297     {
 298       config_event = ev_new(&root_pool);
 299       config_event->hook = config_done;
 300     }
 301   return CONF_PROGRESS;
 302 }
 303
 304 /**
 305  * order_shutdown - order BIRD shutdown
 306  *
 307  * This function initiates shutdown of BIRD. It's accomplished by asking
 308  * for switching to an empty configuration.
 309  */
 310 void
 311 order_shutdown(void)
 312 {
 313   struct config *c;
 314
 315   if (shutting_down)
 316     return;
 317   log(L_INFO "Shutting down");
 318   c = lp_alloc(config->mem, sizeof(struct config));
 319   memcpy(c, config, sizeof(struct config));
 320   init_list(&c->protos);
 321   init_list(&c->tables);
 322   c->shutdown = 1;
 323   shutting_down = 1;
 324   config_commit(c);
 325   shutting_down = 2;
 326 }
 327
 328 /**
 329  * cf_error - report a configuration error
 330  * @msg: printf-like format string
 331  *
 332  * cf_error() can be called during execution of config_parse(), that is
 333  * from the parser, a preconfig hook or a postconfig hook, to report an
 334  * error in the configuration.
 335  */
 336 void
 337 cf_error(char *msg, ...)
 338 {
 339   char buf[1024];
 340   va_list args;
 341
 342   va_start(args, msg);
 343   if (bvsnprintf(buf, sizeof(buf), msg, args) < 0)
 344     strcpy(buf, "<bug: error message too long>");
 345   new_config->err_msg = cfg_strdup(buf);
 346   new_config->err_lino = conf_lino;
 347   longjmp(conf_jmpbuf, 1);
 348 }
 349
 350 /**
 351  * cfg_strdup - copy a string to config memory
 352  * @c: string to copy
 353  *
 354  * cfg_strdup() creates a new copy of the string in the memory
 355  * pool associated with the configuration being currently parsed.
 356  * It's often used when a string literal occurs in the configuration
 357  * and we want to preserve it for further use.
 358  */
 359 char *
 360 cfg_strdup(char *c)
 361 {
 362   int l = strlen(c) + 1;
 363   char *z = cfg_allocu(l);
 364   memcpy(z, c, l);
 365   return z;
 366 }