networking/udhcp/files.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * files.c -- DHCP server file manipulation *
   4  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   5  *
   6  * Licensed under GPLv2, see file LICENSE in this tarball for details.
   7  */
   8
   9 #include <netinet/ether.h>
  10
  11 #include "common.h"
  12 #include "dhcpd.h"
  13
  14 #if BB_LITTLE_ENDIAN
  15 static inline uint64_t hton64(uint64_t v)
  16 {
  17         return (((uint64_t)htonl(v)) << 32) | htonl(v >> 32);
  18 }
  19 #else
  20 #define hton64(v) (v)
  21 #endif
  22 #define ntoh64(v) hton64(v)
  23
  24 /* on these functions, make sure your datatype matches */
  25 static int FAST_FUNC read_nip(const char *line, void *arg)
  26 {
  27         len_and_sockaddr *lsa;
  28
  29         lsa = host_and_af2sockaddr(line, 0, AF_INET);
  30         if (!lsa)
  31                 return 0;
  32         *(uint32_t*)arg = lsa->u.sin.sin_addr.s_addr;
  33         free(lsa);
  34         return 1;
  35 }
  36
  37 static int FAST_FUNC read_mac(const char *line, void *arg)
  38 {
  39         return NULL == ether_aton_r(line, (struct ether_addr *)arg);
  40 }
  41
  42 static int FAST_FUNC read_str(const char *line, void *arg)
  43 {
  44         char **dest = arg;
  45
  46         free(*dest);
  47         *dest = xstrdup(line);
  48         return 1;
  49 }
  50
  51 static int FAST_FUNC read_u32(const char *line, void *arg)
  52 {
  53         *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
  54         return errno == 0;
  55 }
  56
  57 static int read_yn(const char *line, void *arg)
  58 {
  59         char *dest = arg;
  60
  61         if (strcasecmp("yes", line) == 0) {
  62                 *dest = 1;
  63                 return 1;
  64         }
  65         if (strcasecmp("no", line) == 0) {
  66                 *dest = 0;
  67                 return 1;
  68         }
  69         return 0;
  70 }
  71
  72 /* find option 'code' in opt_list */
  73 struct option_set* FAST_FUNC find_option(struct option_set *opt_list, uint8_t code)
  74 {
  75         while (opt_list && opt_list->data[OPT_CODE] < code)
  76                 opt_list = opt_list->next;
  77
  78         if (opt_list && opt_list->data[OPT_CODE] == code)
  79                 return opt_list;
  80         return NULL;
  81 }
  82
  83 /* add an option to the opt_list */
  84 static NOINLINE void attach_option(
  85                 struct option_set **opt_list,
  86                 const struct dhcp_option *option,
  87                 char *buffer,
  88                 int length)
  89 {
  90         struct option_set *existing, *new, **curr;
  91 #if ENABLE_FEATURE_UDHCP_RFC3397
  92         char *allocated = NULL;
  93 #endif
  94
  95         existing = find_option(*opt_list, option->code);
  96         if (!existing) {
  97                 log2("Attaching option %02x to list", option->code);
  98 #if ENABLE_FEATURE_UDHCP_RFC3397
  99                 if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035) {
 100                         /* reuse buffer and length for RFC1035-formatted string */
 101                         allocated = buffer = (char *)dname_enc(NULL, 0, buffer, &length);
 102                 }
 103 #endif
 104                 /* make a new option */
 105                 new = xmalloc(sizeof(*new));
 106                 new->data = xmalloc(length + OPT_DATA);
 107                 new->data[OPT_CODE] = option->code;
 108                 new->data[OPT_LEN] = length;
 109                 memcpy(new->data + OPT_DATA, buffer, length);
 110
 111                 curr = opt_list;
 112                 while (*curr && (*curr)->data[OPT_CODE] < option->code)
 113                         curr = &(*curr)->next;
 114
 115                 new->next = *curr;
 116                 *curr = new;
 117                 goto ret;
 118         }
 119
 120         if (option->flags & OPTION_LIST) {
 121                 unsigned old_len;
 122
 123                 /* add it to an existing option */
 124                 log1("Attaching option %02x to existing member of list", option->code);
 125                 old_len = existing->data[OPT_LEN];
 126 #if ENABLE_FEATURE_UDHCP_RFC3397
 127                 if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035) {
 128                         /* reuse buffer and length for RFC1035-formatted string */
 129                         allocated = buffer = (char *)dname_enc(existing->data + OPT_DATA, old_len, buffer, &length);
 130                 }
 131 #endif
 132                 if (old_len + length < 255) {
 133                         /* actually 255 is ok too, but adding a space can overlow it */
 134
 135                         existing->data = xrealloc(existing->data, OPT_DATA + 1 + old_len + length);
 136                         if ((option->flags & OPTION_TYPE_MASK) == OPTION_STRING) {
 137                                 /* add space separator between STRING options in a list */
 138                                 existing->data[OPT_DATA + old_len] = ' ';
 139                                 old_len++;
 140                         }
 141                         memcpy(existing->data + OPT_DATA + old_len, buffer, length);
 142                         existing->data[OPT_LEN] = old_len + length;
 143                 } /* else, ignore the data, we could put this in a second option in the future */
 144         } /* else, ignore the new data */
 145
 146  ret: ;
 147 #if ENABLE_FEATURE_UDHCP_RFC3397
 148         free(allocated);
 149 #endif
 150 }
 151
 152 /* read a dhcp option and add it to opt_list */
 153 static int FAST_FUNC read_opt(const char *const_line, void *arg)
 154 {
 155         struct option_set **opt_list = arg;
 156         char *opt, *val, *endptr;
 157         char *line;
 158         const struct dhcp_option *option;
 159         int retval, length, idx;
 160         char buffer[8] ALIGNED(4);
 161         uint16_t *result_u16 = (uint16_t *) buffer;
 162         uint32_t *result_u32 = (uint32_t *) buffer;
 163
 164         /* Cheat, the only *const* line possible is "" */
 165         line = (char *) const_line;
 166         opt = strtok(line, " \t=");
 167         if (!opt)
 168                 return 0;
 169
 170         idx = index_in_strings(dhcp_option_strings, opt); /* NB: was strcasecmp! */
 171         if (idx < 0)
 172                 return 0;
 173         option = &dhcp_options[idx];
 174
 175         retval = 0;
 176         do {
 177                 val = strtok(NULL, ", \t");
 178                 if (!val)
 179                         break;
 180                 length = dhcp_option_lengths[option->flags & OPTION_TYPE_MASK];
 181                 retval = 0;
 182                 opt = buffer; /* new meaning for variable opt */
 183                 switch (option->flags & OPTION_TYPE_MASK) {
 184                 case OPTION_IP:
 185                         retval = read_nip(val, buffer);
 186                         break;
 187                 case OPTION_IP_PAIR:
 188                         retval = read_nip(val, buffer);
 189                         val = strtok(NULL, ", \t/-");
 190                         if (!val)
 191                                 retval = 0;
 192                         if (retval)
 193                                 retval = read_nip(val, buffer + 4);
 194                         break;
 195                 case OPTION_STRING:
 196 #if ENABLE_FEATURE_UDHCP_RFC3397
 197                 case OPTION_STR1035:
 198 #endif
 199                         length = strnlen(val, 254);
 200                         if (length > 0) {
 201                                 opt = val;
 202                                 retval = 1;
 203                         }
 204                         break;
 205                 case OPTION_BOOLEAN:
 206                         retval = read_yn(val, buffer);
 207                         break;
 208                 case OPTION_U8:
 209                         buffer[0] = strtoul(val, &endptr, 0);
 210                         retval = (endptr[0] == '\0');
 211                         break;
 212                 /* htonX are macros in older libc's, using temp var
 213                  * in code below for safety */
 214                 /* TODO: use bb_strtoX? */
 215                 case OPTION_U16: {
 216                         unsigned long tmp = strtoul(val, &endptr, 0);
 217                         *result_u16 = htons(tmp);
 218                         retval = (endptr[0] == '\0' /*&& tmp < 0x10000*/);
 219                         break;
 220                 }
 221                 case OPTION_S16: {
 222                         long tmp = strtol(val, &endptr, 0);
 223                         *result_u16 = htons(tmp);
 224                         retval = (endptr[0] == '\0');
 225                         break;
 226                 }
 227                 case OPTION_U32: {
 228                         unsigned long tmp = strtoul(val, &endptr, 0);
 229                         *result_u32 = htonl(tmp);
 230                         retval = (endptr[0] == '\0');
 231                         break;
 232                 }
 233                 case OPTION_S32: {
 234                         long tmp = strtol(val, &endptr, 0);
 235                         *result_u32 = htonl(tmp);
 236                         retval = (endptr[0] == '\0');
 237                         break;
 238                 }
 239                 default:
 240                         break;
 241                 }
 242                 if (retval)
 243                         attach_option(opt_list, option, opt, length);
 244         } while (retval && option->flags & OPTION_LIST);
 245         return retval;
 246 }
 247
 248 static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
 249 {
 250         char *line;
 251         char *mac_string;
 252         char *ip_string;
 253         struct ether_addr mac_bytes;
 254         uint32_t ip;
 255
 256         /* Read mac */
 257         line = (char *) const_line;
 258         mac_string = strtok_r(line, " \t", &line);
 259         read_mac(mac_string, &mac_bytes);
 260
 261         /* Read ip */
 262         ip_string = strtok_r(NULL, " \t", &line);
 263         read_nip(ip_string, &ip);
 264
 265         add_static_lease(arg, (uint8_t*) &mac_bytes, ip);
 266
 267         log_static_leases(arg);
 268
 269         return 1;
 270 }
 271
 272
 273 struct config_keyword {
 274         const char *keyword;
 275         int (*handler)(const char *line, void *var) FAST_FUNC;
 276         void *var;
 277         const char *def;
 278 };
 279
 280 static const struct config_keyword keywords[] = {
 281         /* keyword       handler   variable address               default */
 282         {"start",        read_nip, &(server_config.start_ip),     "192.168.0.20"},
 283         {"end",          read_nip, &(server_config.end_ip),       "192.168.0.254"},
 284         {"interface",    read_str, &(server_config.interface),    "eth0"},
 285         /* Avoid "max_leases value not sane" warning by setting default
 286          * to default_end_ip - default_start_ip + 1: */
 287         {"max_leases",   read_u32, &(server_config.max_leases),   "235"},
 288         {"auto_time",    read_u32, &(server_config.auto_time),    "7200"},
 289         {"decline_time", read_u32, &(server_config.decline_time), "3600"},
 290         {"conflict_time",read_u32, &(server_config.conflict_time),"3600"},
 291         {"offer_time",   read_u32, &(server_config.offer_time),   "60"},
 292         {"min_lease",    read_u32, &(server_config.min_lease_sec),"60"},
 293         {"lease_file",   read_str, &(server_config.lease_file),   LEASES_FILE},
 294         {"pidfile",      read_str, &(server_config.pidfile),      "/var/run/udhcpd.pid"},
 295         {"siaddr",       read_nip, &(server_config.siaddr_nip),   "0.0.0.0"},
 296         /* keywords with no defaults must be last! */
 297         {"option",       read_opt, &(server_config.options),      ""},
 298         {"opt",          read_opt, &(server_config.options),      ""},
 299         {"notify_file",  read_str, &(server_config.notify_file),  ""},
 300         {"sname",        read_str, &(server_config.sname),        ""},
 301         {"boot_file",    read_str, &(server_config.boot_file),    ""},
 302         {"static_lease", read_staticlease, &(server_config.static_leases), ""},
 303 };
 304 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
 305
 306 void FAST_FUNC read_config(const char *file)
 307 {
 308         parser_t *parser;
 309         const struct config_keyword *k;
 310         unsigned i;
 311         char *token[2];
 312
 313         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
 314                 keywords[i].handler(keywords[i].def, keywords[i].var);
 315
 316         parser = config_open(file);
 317         while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
 318                 for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
 319                         if (!strcasecmp(token[0], k->keyword)) {
 320                                 if (!k->handler(token[1], k->var)) {
 321                                         bb_error_msg("can't parse line %u in %s",
 322                                                         parser->lineno, file);
 323                                         /* reset back to the default value */
 324                                         k->handler(k->def, k->var);
 325                                 }
 326                                 break;
 327                         }
 328                 }
 329         }
 330         config_close(parser);
 331
 332         server_config.start_ip = ntohl(server_config.start_ip);
 333         server_config.end_ip = ntohl(server_config.end_ip);
 334 }
 335
 336 void FAST_FUNC write_leases(void)
 337 {
 338         int fd;
 339         unsigned i;
 340         leasetime_t curr;
 341         int64_t written_at;
 342
 343         fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 344         if (fd < 0)
 345                 return;
 346
 347         curr = written_at = time(NULL);
 348
 349         written_at = hton64(written_at);
 350         full_write(fd, &written_at, sizeof(written_at));
 351
 352         for (i = 0; i < server_config.max_leases; i++) {
 353                 leasetime_t tmp_time;
 354
 355                 if (g_leases[i].lease_nip == 0)
 356                         continue;
 357
 358                 /* Screw with the time in the struct, for easier writing */
 359                 tmp_time = g_leases[i].expires;
 360
 361                 g_leases[i].expires -= curr;
 362                 if ((signed_leasetime_t) g_leases[i].expires < 0)
 363                         g_leases[i].expires = 0;
 364                 g_leases[i].expires = htonl(g_leases[i].expires);
 365
 366                 /* No error check. If the file gets truncated,
 367                  * we lose some leases on restart. Oh well. */
 368                 full_write(fd, &g_leases[i], sizeof(g_leases[i]));
 369
 370                 /* Then restore it when done */
 371                 g_leases[i].expires = tmp_time;
 372         }
 373         close(fd);
 374
 375         if (server_config.notify_file) {
 376 // TODO: vfork-based child creation
 377                 char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
 378                 system(cmd);
 379                 free(cmd);
 380         }
 381 }
 382
 383 void FAST_FUNC read_leases(const char *file)
 384 {
 385         struct dyn_lease lease;
 386         int64_t written_at, time_passed;
 387         int fd;
 388 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 389         unsigned i = 0;
 390 #endif
 391
 392         fd = open_or_warn(file, O_RDONLY);
 393         if (fd < 0)
 394                 return;
 395
 396         if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
 397                 goto ret;
 398         written_at = ntoh64(written_at);
 399
 400         time_passed = time(NULL) - written_at;
 401         /* Strange written_at, or lease file from old version of udhcpd
 402          * which had no "written_at" field? */
 403         if ((uint64_t)time_passed > 12 * 60 * 60)
 404                 goto ret;
 405
 406         while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
 407 //FIXME: what if it matches some static lease?
 408                 uint32_t y = ntohl(lease.lease_nip);
 409                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 410                         signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
 411                         if (expires <= 0)
 412                                 continue;
 413                         /* NB: add_lease takes "relative time", IOW,
 414                          * lease duration, not lease deadline. */
 415                         if (add_lease(lease.lease_mac, lease.lease_nip,
 416                                         expires,
 417                                         lease.hostname, sizeof(lease.hostname)
 418                                 ) == 0
 419                         ) {
 420                                 bb_error_msg("too many leases while loading %s", file);
 421                                 break;
 422                         }
 423 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 424                         i++;
 425 #endif
 426                 }
 427         }
 428         log1("Read %d leases", i);
 429  ret:
 430         close(fd);
 431 }