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
  25 /* on these functions, make sure your datatype matches */
  26 static int FAST_FUNC read_nip(const char *line, void *arg)
  27 {
  28         len_and_sockaddr *lsa;
  29
  30         lsa = host_and_af2sockaddr(line, 0, AF_INET);
  31         if (!lsa)
  32                 return 0;
  33         *(uint32_t*)arg = lsa->u.sin.sin_addr.s_addr;
  34         free(lsa);
  35         return 1;
  36 }
  37
  38
  39 static int FAST_FUNC read_mac(const char *line, void *arg)
  40 {
  41         return NULL == ether_aton_r(line, (struct ether_addr *)arg);
  42 }
  43
  44
  45 static int FAST_FUNC read_str(const char *line, void *arg)
  46 {
  47         char **dest = arg;
  48
  49         free(*dest);
  50         *dest = xstrdup(line);
  51         return 1;
  52 }
  53
  54
  55 static int FAST_FUNC read_u32(const char *line, void *arg)
  56 {
  57         *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
  58         return errno == 0;
  59 }
  60
  61
  62 static int FAST_FUNC read_yn(const char *line, void *arg)
  63 {
  64         char *dest = arg;
  65
  66         if (!strcasecmp("yes", line)) {
  67                 *dest = 1;
  68                 return 1;
  69         }
  70         if (!strcasecmp("no", line)) {
  71                 *dest = 0;
  72                 return 1;
  73         }
  74         return 0;
  75 }
  76
  77
  78 /* find option 'code' in opt_list */
  79 struct option_set* FAST_FUNC find_option(struct option_set *opt_list, uint8_t code)
  80 {
  81         while (opt_list && opt_list->data[OPT_CODE] < code)
  82                 opt_list = opt_list->next;
  83
  84         if (opt_list && opt_list->data[OPT_CODE] == code)
  85                 return opt_list;
  86         return NULL;
  87 }
  88
  89
  90 /* add an option to the opt_list */
  91 static void attach_option(struct option_set **opt_list,
  92                 const struct dhcp_option *option, char *buffer, int length)
  93 {
  94         struct option_set *existing, *new, **curr;
  95
  96         existing = find_option(*opt_list, option->code);
  97         if (!existing) {
  98                 log2("Attaching option %02x to list", option->code);
  99
 100 #if ENABLE_FEATURE_UDHCP_RFC3397
 101                 if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035)
 102                         /* reuse buffer and length for RFC1035-formatted string */
 103                         buffer = (char *)dname_enc(NULL, 0, buffer, &length);
 104 #endif
 105
 106                 /* make a new option */
 107                 new = xmalloc(sizeof(*new));
 108                 new->data = xmalloc(length + 2);
 109                 new->data[OPT_CODE] = option->code;
 110                 new->data[OPT_LEN] = length;
 111                 memcpy(new->data + 2, buffer, length);
 112
 113                 curr = opt_list;
 114                 while (*curr && (*curr)->data[OPT_CODE] < option->code)
 115                         curr = &(*curr)->next;
 116
 117                 new->next = *curr;
 118                 *curr = new;
 119 #if ENABLE_FEATURE_UDHCP_RFC3397
 120                 if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 121                         free(buffer);
 122 #endif
 123                 return;
 124         }
 125
 126         /* add it to an existing option */
 127         log1("Attaching option %02x to existing member of list", option->code);
 128         if (option->flags & OPTION_LIST) {
 129 #if ENABLE_FEATURE_UDHCP_RFC3397
 130                 if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035)
 131                         /* reuse buffer and length for RFC1035-formatted string */
 132                         buffer = (char *)dname_enc(existing->data + 2,
 133                                         existing->data[OPT_LEN], buffer, &length);
 134 #endif
 135                 if (existing->data[OPT_LEN] + length <= 255) {
 136                         existing->data = xrealloc(existing->data,
 137                                         existing->data[OPT_LEN] + length + 3);
 138                         if ((option->flags & OPTION_TYPE_MASK) == OPTION_STRING) {
 139                                 /* ' ' can bring us to 256 - bad */
 140                                 if (existing->data[OPT_LEN] + length >= 255)
 141                                         return;
 142                                 /* add space separator between STRING options in a list */
 143                                 existing->data[existing->data[OPT_LEN] + 2] = ' ';
 144                                 existing->data[OPT_LEN]++;
 145                         }
 146                         memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
 147                         existing->data[OPT_LEN] += length;
 148                 } /* else, ignore the data, we could put this in a second option in the future */
 149 #if ENABLE_FEATURE_UDHCP_RFC3397
 150                 if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 151                         free(buffer);
 152 #endif
 153         } /* else, ignore the new data */
 154 }
 155
 156
 157 /* read a dhcp option and add it to opt_list */
 158 static int FAST_FUNC read_opt(const char *const_line, void *arg)
 159 {
 160         struct option_set **opt_list = arg;
 161         char *opt, *val, *endptr;
 162         char *line;
 163         const struct dhcp_option *option;
 164         int retval, length, idx;
 165         char buffer[8] ALIGNED(4);
 166         uint16_t *result_u16 = (uint16_t *) buffer;
 167         uint32_t *result_u32 = (uint32_t *) buffer;
 168
 169         /* Cheat, the only const line we'll actually get is "" */
 170         line = (char *) const_line;
 171         opt = strtok(line, " \t=");
 172         if (!opt)
 173                 return 0;
 174
 175         idx = index_in_strings(dhcp_option_strings, opt); /* NB: was strcasecmp! */
 176         if (idx < 0)
 177                 return 0;
 178         option = &dhcp_options[idx];
 179
 180         retval = 0;
 181         do {
 182                 val = strtok(NULL, ", \t");
 183                 if (!val) break;
 184                 length = dhcp_option_lengths[option->flags & OPTION_TYPE_MASK];
 185                 retval = 0;
 186                 opt = buffer; /* new meaning for variable opt */
 187                 switch (option->flags & OPTION_TYPE_MASK) {
 188                 case OPTION_IP:
 189                         retval = read_nip(val, buffer);
 190                         break;
 191                 case OPTION_IP_PAIR:
 192                         retval = read_nip(val, buffer);
 193                         val = strtok(NULL, ", \t/-");
 194                         if (!val)
 195                                 retval = 0;
 196                         if (retval)
 197                                 retval = read_nip(val, buffer + 4);
 198                         break;
 199                 case OPTION_STRING:
 200 #if ENABLE_FEATURE_UDHCP_RFC3397
 201                 case OPTION_STR1035:
 202 #endif
 203                         length = strnlen(val, 254);
 204                         if (length > 0) {
 205                                 opt = val;
 206                                 retval = 1;
 207                         }
 208                         break;
 209                 case OPTION_BOOLEAN:
 210                         retval = read_yn(val, buffer);
 211                         break;
 212                 case OPTION_U8:
 213                         buffer[0] = strtoul(val, &endptr, 0);
 214                         retval = (endptr[0] == '\0');
 215                         break;
 216                 /* htonX are macros in older libc's, using temp var
 217                  * in code below for safety */
 218                 /* TODO: use bb_strtoX? */
 219                 case OPTION_U16: {
 220                         unsigned long tmp = strtoul(val, &endptr, 0);
 221                         *result_u16 = htons(tmp);
 222                         retval = (endptr[0] == '\0' /*&& tmp < 0x10000*/);
 223                         break;
 224                 }
 225                 case OPTION_S16: {
 226                         long tmp = strtol(val, &endptr, 0);
 227                         *result_u16 = htons(tmp);
 228                         retval = (endptr[0] == '\0');
 229                         break;
 230                 }
 231                 case OPTION_U32: {
 232                         unsigned long tmp = strtoul(val, &endptr, 0);
 233                         *result_u32 = htonl(tmp);
 234                         retval = (endptr[0] == '\0');
 235                         break;
 236                 }
 237                 case OPTION_S32: {
 238                         long tmp = strtol(val, &endptr, 0);
 239                         *result_u32 = htonl(tmp);
 240                         retval = (endptr[0] == '\0');
 241                         break;
 242                 }
 243                 default:
 244                         break;
 245                 }
 246                 if (retval)
 247                         attach_option(opt_list, option, opt, length);
 248         } while (retval && option->flags & OPTION_LIST);
 249         return retval;
 250 }
 251
 252 static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
 253 {
 254         char *line;
 255         char *mac_string;
 256         char *ip_string;
 257         struct ether_addr mac_bytes;
 258         uint32_t ip;
 259
 260         /* Read mac */
 261         line = (char *) const_line;
 262         mac_string = strtok_r(line, " \t", &line);
 263         read_mac(mac_string, &mac_bytes);
 264
 265         /* Read ip */
 266         ip_string = strtok_r(NULL, " \t", &line);
 267         read_nip(ip_string, &ip);
 268
 269         add_static_lease(arg, (uint8_t*) &mac_bytes, ip);
 270
 271         log_static_leases(arg);
 272
 273         return 1;
 274 }
 275
 276
 277 struct config_keyword {
 278         const char *keyword;
 279         int (*handler)(const char *line, void *var) FAST_FUNC;
 280         void *var;
 281         const char *def;
 282 };
 283
 284 static const struct config_keyword keywords[] = {
 285         /* keyword       handler   variable address               default */
 286         {"start",        read_nip, &(server_config.start_ip),     "192.168.0.20"},
 287         {"end",          read_nip, &(server_config.end_ip),       "192.168.0.254"},
 288         {"interface",    read_str, &(server_config.interface),    "eth0"},
 289         /* Avoid "max_leases value not sane" warning by setting default
 290          * to default_end_ip - default_start_ip + 1: */
 291         {"max_leases",   read_u32, &(server_config.max_leases),   "235"},
 292         {"auto_time",    read_u32, &(server_config.auto_time),    "7200"},
 293         {"decline_time", read_u32, &(server_config.decline_time), "3600"},
 294         {"conflict_time",read_u32, &(server_config.conflict_time),"3600"},
 295         {"offer_time",   read_u32, &(server_config.offer_time),   "60"},
 296         {"min_lease",    read_u32, &(server_config.min_lease_sec),"60"},
 297         {"lease_file",   read_str, &(server_config.lease_file),   LEASES_FILE},
 298         {"pidfile",      read_str, &(server_config.pidfile),      "/var/run/udhcpd.pid"},
 299         {"siaddr",       read_nip, &(server_config.siaddr_nip),   "0.0.0.0"},
 300         /* keywords with no defaults must be last! */
 301         {"option",       read_opt, &(server_config.options),      ""},
 302         {"opt",          read_opt, &(server_config.options),      ""},
 303         {"notify_file",  read_str, &(server_config.notify_file),  ""},
 304         {"sname",        read_str, &(server_config.sname),        ""},
 305         {"boot_file",    read_str, &(server_config.boot_file),    ""},
 306         {"static_lease", read_staticlease, &(server_config.static_leases), ""},
 307 };
 308 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
 309
 310 void FAST_FUNC read_config(const char *file)
 311 {
 312         parser_t *parser;
 313         const struct config_keyword *k;
 314         unsigned i;
 315         char *token[2];
 316
 317         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
 318                 keywords[i].handler(keywords[i].def, keywords[i].var);
 319
 320         parser = config_open(file);
 321         while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
 322                 for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
 323                         if (!strcasecmp(token[0], k->keyword)) {
 324                                 if (!k->handler(token[1], k->var)) {
 325                                         bb_error_msg("can't parse line %u in %s",
 326                                                         parser->lineno, file);
 327                                         /* reset back to the default value */
 328                                         k->handler(k->def, k->var);
 329                                 }
 330                                 break;
 331                         }
 332                 }
 333         }
 334         config_close(parser);
 335
 336         server_config.start_ip = ntohl(server_config.start_ip);
 337         server_config.end_ip = ntohl(server_config.end_ip);
 338 }
 339
 340
 341 void FAST_FUNC write_leases(void)
 342 {
 343         int fd;
 344         unsigned i;
 345         leasetime_t curr;
 346         int64_t written_at;
 347
 348         fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 349         if (fd < 0)
 350                 return;
 351
 352         curr = written_at = time(NULL);
 353
 354         written_at = hton64(written_at);
 355         full_write(fd, &written_at, sizeof(written_at));
 356
 357         for (i = 0; i < server_config.max_leases; i++) {
 358                 leasetime_t tmp_time;
 359
 360                 if (g_leases[i].lease_nip == 0)
 361                         continue;
 362
 363                 /* Screw with the time in the struct, for easier writing */
 364                 tmp_time = g_leases[i].expires;
 365
 366                 g_leases[i].expires -= curr;
 367                 if ((signed_leasetime_t) g_leases[i].expires < 0)
 368                         g_leases[i].expires = 0;
 369                 g_leases[i].expires = htonl(g_leases[i].expires);
 370
 371                 /* No error check. If the file gets truncated,
 372                  * we lose some leases on restart. Oh well. */
 373                 full_write(fd, &g_leases[i], sizeof(g_leases[i]));
 374
 375                 /* Then restore it when done */
 376                 g_leases[i].expires = tmp_time;
 377         }
 378         close(fd);
 379
 380         if (server_config.notify_file) {
 381 // TODO: vfork-based child creation
 382                 char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
 383                 system(cmd);
 384                 free(cmd);
 385         }
 386 }
 387
 388
 389 void FAST_FUNC read_leases(const char *file)
 390 {
 391         struct dyn_lease lease;
 392         int64_t written_at, time_passed;
 393         int fd;
 394 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 395         unsigned i = 0;
 396 #endif
 397
 398         fd = open_or_warn(file, O_RDONLY);
 399         if (fd < 0)
 400                 return;
 401
 402         if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
 403                 goto ret;
 404         written_at = ntoh64(written_at);
 405
 406         time_passed = time(NULL) - written_at;
 407         /* Strange written_at, or lease file from old version of udhcpd
 408          * which had no "written_at" field? */
 409         if ((uint64_t)time_passed > 12 * 60 * 60)
 410                 goto ret;
 411
 412         while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
 413 //FIXME: what if it matches some static lease?
 414                 uint32_t y = ntohl(lease.lease_nip);
 415                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 416                         signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
 417                         if (expires <= 0)
 418                                 continue;
 419                         /* NB: add_lease takes "relative time", IOW,
 420                          * lease duration, not lease deadline. */
 421                         if (add_lease(lease.lease_mac, lease.lease_nip,
 422                                         expires,
 423                                         lease.hostname, sizeof(lease.hostname)
 424                                 ) == 0
 425                         ) {
 426                                 bb_error_msg("too many leases while loading %s", file);
 427                                 break;
 428                         }
 429 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
 430                         i++;
 431 #endif
 432                 }
 433         }
 434         log1("Read %d leases", i);
 435  ret:
 436         close(fd);
 437 }