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