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 #include "options.h"
  14
  15 #if BB_LITTLE_ENDIAN
  16 static inline uint64_t hton64(uint64_t v)
  17 {
  18         return (((uint64_t)htonl(v)) << 32) | htonl(v >> 32);
  19 }
  20 #else
  21 #define hton64(v) (v)
  22 #endif
  23 #define ntoh64(v) hton64(v)
  24
  25
  26 /* on these functions, make sure your datatype matches */
  27 static int read_ip(const char *line, void *arg)
  28 {
  29         len_and_sockaddr *lsa;
  30
  31         lsa = host_and_af2sockaddr(line, 0, AF_INET);
  32         if (!lsa)
  33                 return 0;
  34         *(uint32_t*)arg = lsa->u.sin.sin_addr.s_addr;
  35         free(lsa);
  36         return 1;
  37 }
  38
  39
  40 static int read_mac(const char *line, void *arg)
  41 {
  42         return NULL == ether_aton_r(line, (struct ether_addr *)arg);
  43 }
  44
  45
  46 static int read_str(const char *line, void *arg)
  47 {
  48         char **dest = arg;
  49
  50         free(*dest);
  51         *dest = xstrdup(line);
  52         return 1;
  53 }
  54
  55
  56 static int read_u32(const char *line, void *arg)
  57 {
  58         *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
  59         return errno == 0;
  60 }
  61
  62
  63 static int read_yn(const char *line, void *arg)
  64 {
  65         char *dest = arg;
  66
  67         if (!strcasecmp("yes", line)) {
  68                 *dest = 1;
  69                 return 1;
  70         }
  71         if (!strcasecmp("no", line)) {
  72                 *dest = 0;
  73                 return 1;
  74         }
  75         return 0;
  76 }
  77
  78
  79 /* find option 'code' in opt_list */
  80 struct option_set* FAST_FUNC find_option(struct option_set *opt_list, uint8_t code)
  81 {
  82         while (opt_list && opt_list->data[OPT_CODE] < code)
  83                 opt_list = opt_list->next;
  84
  85         if (opt_list && opt_list->data[OPT_CODE] == code)
  86                 return opt_list;
  87         return NULL;
  88 }
  89
  90
  91 /* add an option to the opt_list */
  92 static void attach_option(struct option_set **opt_list,
  93                 const struct dhcp_option *option, char *buffer, int length)
  94 {
  95         struct option_set *existing, *new, **curr;
  96
  97         existing = find_option(*opt_list, option->code);
  98         if (!existing) {
  99                 DEBUG("Attaching option %02x to list", option->code);
 100
 101 #if ENABLE_FEATURE_UDHCP_RFC3397
 102                 if ((option->flags & TYPE_MASK) == OPTION_STR1035)
 103                         /* reuse buffer and length for RFC1035-formatted string */
 104                         buffer = (char *)dname_enc(NULL, 0, buffer, &length);
 105 #endif
 106
 107                 /* make a new option */
 108                 new = xmalloc(sizeof(*new));
 109                 new->data = xmalloc(length + 2);
 110                 new->data[OPT_CODE] = option->code;
 111                 new->data[OPT_LEN] = length;
 112                 memcpy(new->data + 2, buffer, length);
 113
 114                 curr = opt_list;
 115                 while (*curr && (*curr)->data[OPT_CODE] < option->code)
 116                         curr = &(*curr)->next;
 117
 118                 new->next = *curr;
 119                 *curr = new;
 120 #if ENABLE_FEATURE_UDHCP_RFC3397
 121                 if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 122                         free(buffer);
 123 #endif
 124                 return;
 125         }
 126
 127         /* add it to an existing option */
 128         DEBUG("Attaching option %02x to existing member of list", option->code);
 129         if (option->flags & OPTION_LIST) {
 130 #if ENABLE_FEATURE_UDHCP_RFC3397
 131                 if ((option->flags & TYPE_MASK) == OPTION_STR1035)
 132                         /* reuse buffer and length for RFC1035-formatted string */
 133                         buffer = (char *)dname_enc(existing->data + 2,
 134                                         existing->data[OPT_LEN], buffer, &length);
 135 #endif
 136                 if (existing->data[OPT_LEN] + length <= 255) {
 137                         existing->data = xrealloc(existing->data,
 138                                         existing->data[OPT_LEN] + length + 3);
 139                         if ((option->flags & TYPE_MASK) == OPTION_STRING) {
 140                                 /* ' ' can bring us to 256 - bad */
 141                                 if (existing->data[OPT_LEN] + length >= 255)
 142                                         return;
 143                                 /* add space separator between STRING options in a list */
 144                                 existing->data[existing->data[OPT_LEN] + 2] = ' ';
 145                                 existing->data[OPT_LEN]++;
 146                         }
 147                         memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
 148                         existing->data[OPT_LEN] += length;
 149                 } /* else, ignore the data, we could put this in a second option in the future */
 150 #if ENABLE_FEATURE_UDHCP_RFC3397
 151                 if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 152                         free(buffer);
 153 #endif
 154         } /* else, ignore the new data */
 155 }
 156
 157
 158 /* read a dhcp option and add it to opt_list */
 159 static int read_opt(const char *const_line, void *arg)
 160 {
 161         struct option_set **opt_list = arg;
 162         char *opt, *val, *endptr;
 163         char *line;
 164         const struct dhcp_option *option;
 165         int retval, length, idx;
 166         char buffer[8] ALIGNED(4);
 167         uint16_t *result_u16 = (uint16_t *) buffer;
 168         uint32_t *result_u32 = (uint32_t *) buffer;
 169
 170         /* Cheat, the only const line we'll actually get is "" */
 171         line = (char *) const_line;
 172         opt = strtok(line, " \t=");
 173         if (!opt)
 174                 return 0;
 175
 176         idx = index_in_strings(dhcp_option_strings, opt); /* NB: was strcasecmp! */
 177         if (idx < 0)
 178                 return 0;
 179         option = &dhcp_options[idx];
 180
 181         retval = 0;
 182         do {
 183                 val = strtok(NULL, ", \t");
 184                 if (!val) break;
 185                 length = dhcp_option_lengths[option->flags & TYPE_MASK];
 186                 retval = 0;
 187                 opt = buffer; /* new meaning for variable opt */
 188                 switch (option->flags & TYPE_MASK) {
 189                 case OPTION_IP:
 190                         retval = read_ip(val, buffer);
 191                         break;
 192                 case OPTION_IP_PAIR:
 193                         retval = read_ip(val, buffer);
 194                         val = strtok(NULL, ", \t/-");
 195                         if (!val)
 196                                 retval = 0;
 197                         if (retval)
 198                                 retval = read_ip(val, buffer + 4);
 199                         break;
 200                 case OPTION_STRING:
 201 #if ENABLE_FEATURE_UDHCP_RFC3397
 202                 case OPTION_STR1035:
 203 #endif
 204                         length = strlen(val);
 205                         if (length > 0) {
 206                                 if (length > 254) length = 254;
 207                                 opt = val;
 208                                 retval = 1;
 209                         }
 210                         break;
 211                 case OPTION_BOOLEAN:
 212                         retval = read_yn(val, buffer);
 213                         break;
 214                 case OPTION_U8:
 215                         buffer[0] = strtoul(val, &endptr, 0);
 216                         retval = (endptr[0] == '\0');
 217                         break;
 218                 /* htonX are macros in older libc's, using temp var
 219                  * in code below for safety */
 220                 /* TODO: use bb_strtoX? */
 221                 case OPTION_U16: {
 222                         unsigned long tmp = strtoul(val, &endptr, 0);
 223                         *result_u16 = htons(tmp);
 224                         retval = (endptr[0] == '\0' /*&& tmp < 0x10000*/);
 225                         break;
 226                 }
 227                 case OPTION_S16: {
 228                         long tmp = strtol(val, &endptr, 0);
 229                         *result_u16 = htons(tmp);
 230                         retval = (endptr[0] == '\0');
 231                         break;
 232                 }
 233                 case OPTION_U32: {
 234                         unsigned long tmp = strtoul(val, &endptr, 0);
 235                         *result_u32 = htonl(tmp);
 236                         retval = (endptr[0] == '\0');
 237                         break;
 238                 }
 239                 case OPTION_S32: {
 240                         long tmp = strtol(val, &endptr, 0);
 241                         *result_u32 = htonl(tmp);
 242                         retval = (endptr[0] == '\0');
 243                         break;
 244                 }
 245                 default:
 246                         break;
 247                 }
 248                 if (retval)
 249                         attach_option(opt_list, option, opt, length);
 250         } while (retval && option->flags & OPTION_LIST);
 251         return retval;
 252 }
 253
 254 static int read_staticlease(const char *const_line, void *arg)
 255 {
 256         char *line;
 257         char *mac_string;
 258         char *ip_string;
 259         struct ether_addr mac_bytes;
 260         uint32_t ip;
 261
 262         /* Read mac */
 263         line = (char *) const_line;
 264         mac_string = strtok_r(line, " \t", &line);
 265         read_mac(mac_string, &mac_bytes);
 266
 267         /* Read ip */
 268         ip_string = strtok_r(NULL, " \t", &line);
 269         read_ip(ip_string, &ip);
 270
 271         addStaticLease(arg, (uint8_t*) &mac_bytes, ip);
 272
 273         if (ENABLE_UDHCP_DEBUG) printStaticLeases(arg);
 274
 275         return 1;
 276 }
 277
 278
 279 struct config_keyword {
 280         const char *keyword;
 281         int (*handler)(const char *line, void *var);
 282         void *var;
 283         const char *def;
 284 };
 285
 286 static const struct config_keyword keywords[] = {
 287         /* keyword       handler   variable address               default */
 288         {"start",        read_ip,  &(server_config.start_ip),     "192.168.0.20"},
 289         {"end",          read_ip,  &(server_config.end_ip),       "192.168.0.254"},
 290         {"interface",    read_str, &(server_config.interface),    "eth0"},
 291         /* Avoid "max_leases value not sane" warning by setting default
 292          * to default_end_ip - default_start_ip + 1: */
 293         {"max_leases",   read_u32, &(server_config.max_leases),   "235"},
 294 //      {"remaining",    read_yn,  &(server_config.remaining),    "yes"},
 295         {"auto_time",    read_u32, &(server_config.auto_time),    "7200"},
 296         {"decline_time", read_u32, &(server_config.decline_time), "3600"},
 297         {"conflict_time",read_u32, &(server_config.conflict_time),"3600"},
 298         {"offer_time",   read_u32, &(server_config.offer_time),   "60"},
 299         {"min_lease",    read_u32, &(server_config.min_lease),    "60"},
 300         {"lease_file",   read_str, &(server_config.lease_file),   LEASES_FILE},
 301         {"pidfile",      read_str, &(server_config.pidfile),      "/var/run/udhcpd.pid"},
 302         {"siaddr",       read_ip,  &(server_config.siaddr),       "0.0.0.0"},
 303         /* keywords with no defaults must be last! */
 304         {"option",       read_opt, &(server_config.options),      ""},
 305         {"opt",          read_opt, &(server_config.options),      ""},
 306         {"notify_file",  read_str, &(server_config.notify_file),  ""},
 307         {"sname",        read_str, &(server_config.sname),        ""},
 308         {"boot_file",    read_str, &(server_config.boot_file),    ""},
 309         {"static_lease", read_staticlease, &(server_config.static_leases), ""},
 310 };
 311 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
 312
 313 void FAST_FUNC read_config(const char *file)
 314 {
 315         parser_t *parser;
 316         const struct config_keyword *k;
 317         unsigned i;
 318         char *token[2];
 319
 320         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
 321                 keywords[i].handler(keywords[i].def, keywords[i].var);
 322
 323         parser = config_open(file);
 324         while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
 325                 for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
 326                         if (!strcasecmp(token[0], k->keyword)) {
 327                                 if (!k->handler(token[1], k->var)) {
 328                                         bb_error_msg("can't parse line %u in %s",
 329                                                         parser->lineno, file);
 330                                         /* reset back to the default value */
 331                                         k->handler(k->def, k->var);
 332                                 }
 333                                 break;
 334                         }
 335                 }
 336         }
 337         config_close(parser);
 338
 339         server_config.start_ip = ntohl(server_config.start_ip);
 340         server_config.end_ip = ntohl(server_config.end_ip);
 341 }
 342
 343
 344 void FAST_FUNC write_leases(void)
 345 {
 346         int fd;
 347         unsigned i;
 348         leasetime_t curr;
 349         int64_t written_at;
 350
 351         fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 352         if (fd < 0)
 353                 return;
 354
 355         curr = written_at = time(NULL);
 356
 357         written_at = hton64(written_at);
 358         full_write(fd, &written_at, sizeof(written_at));
 359
 360         for (i = 0; i < server_config.max_leases; i++) {
 361                 leasetime_t tmp_time;
 362
 363                 if (leases[i].yiaddr == 0)
 364                         continue;
 365
 366                 /* Screw with the time in the struct, for easier writing */
 367                 tmp_time = leases[i].expires;
 368
 369                 leases[i].expires -= curr;
 370                 if ((signed_leasetime_t) leases[i].expires < 0)
 371                         leases[i].expires = 0;
 372                 leases[i].expires = htonl(leases[i].expires);
 373
 374                 /* No error check. If the file gets truncated,
 375                  * we lose some leases on restart. Oh well. */
 376                 full_write(fd, &leases[i], sizeof(leases[i]));
 377
 378                 /* Then restore it when done */
 379                 leases[i].expires = tmp_time;
 380         }
 381         close(fd);
 382
 383         if (server_config.notify_file) {
 384 // TODO: vfork-based child creation
 385                 char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
 386                 system(cmd);
 387                 free(cmd);
 388         }
 389 }
 390
 391
 392 void FAST_FUNC read_leases(const char *file)
 393 {
 394         struct dhcpOfferedAddr lease;
 395         int64_t written_at, time_passed;
 396         int fd;
 397         USE_UDHCP_DEBUG(unsigned i;)
 398
 399         fd = open_or_warn(file, O_RDONLY);
 400         if (fd < 0)
 401                 return;
 402
 403         if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
 404                 goto ret;
 405         written_at = ntoh64(written_at);
 406
 407         time_passed = time(NULL) - written_at;
 408         /* Strange written_at, or lease file from old version of udhcpd
 409          * which had no "written_at" field? */
 410         if ((uint64_t)time_passed > 12 * 60 * 60)
 411                 goto ret;
 412
 413         USE_UDHCP_DEBUG(i = 0;)
 414         while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
 415                 /* ADDME: what if it matches some static lease? */
 416                 uint32_t y = ntohl(lease.yiaddr);
 417                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 418                         signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
 419                         if (expires <= 0)
 420                                 continue;
 421                         /* NB: add_lease takes "relative time", IOW,
 422                          * lease duration, not lease deadline. */
 423                         if (!(add_lease(lease.chaddr, lease.yiaddr, expires, lease.hostname))) {
 424                                 bb_error_msg("too many leases while loading %s", file);
 425                                 break;
 426                         }
 427                         USE_UDHCP_DEBUG(i++;)
 428                 }
 429         }
 430         DEBUG("Read %d leases", i);
 431  ret:
 432         close(fd);
 433 }