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
   7 #include <netinet/ether.h>
   8
   9 #include "common.h"
  10 #include "dhcpd.h"
  11 #include "options.h"
  12
  13
  14 /* on these functions, make sure your datatype matches */
  15 static int read_ip(const char *line, void *arg)
  16 {
  17         len_and_sockaddr *lsa;
  18
  19         lsa = host_and_af2sockaddr(line, 0, AF_INET);
  20         if (!lsa)
  21                 return 0;
  22         *(uint32_t*)arg = lsa->u.sin.sin_addr.s_addr;
  23         free(lsa);
  24         return 1;
  25 }
  26
  27 static int read_mac(const char *line, void *arg)
  28 {
  29         uint8_t *mac_bytes = arg;
  30         struct ether_addr *temp_ether_addr;
  31
  32         temp_ether_addr = ether_aton(line);
  33         if (temp_ether_addr == NULL)
  34                 return 0;
  35         memcpy(mac_bytes, temp_ether_addr, 6);
  36         return 1;
  37 }
  38
  39
  40 static int read_str(const char *line, void *arg)
  41 {
  42         char **dest = arg;
  43
  44         free(*dest);
  45         *dest = xstrdup(line);
  46         return 1;
  47 }
  48
  49
  50 static int read_u32(const char *line, void *arg)
  51 {
  52         *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
  53         return errno == 0;
  54 }
  55
  56
  57 static int read_yn(const char *line, void *arg)
  58 {
  59         char *dest = arg;
  60
  61         if (!strcasecmp("yes", line)) {
  62                 *dest = 1;
  63                 return 1;
  64         }
  65         if (!strcasecmp("no", line)) {
  66                 *dest = 0;
  67                 return 1;
  68         }
  69         return 0;
  70 }
  71
  72
  73 /* find option 'code' in opt_list */
  74 struct option_set *find_option(struct option_set *opt_list, uint8_t code)
  75 {
  76         while (opt_list && opt_list->data[OPT_CODE] < code)
  77                 opt_list = opt_list->next;
  78
  79         if (opt_list && opt_list->data[OPT_CODE] == code)
  80                 return opt_list;
  81         return NULL;
  82 }
  83
  84
  85 /* add an option to the opt_list */
  86 static void attach_option(struct option_set **opt_list,
  87                 const struct dhcp_option *option, char *buffer, int length)
  88 {
  89         struct option_set *existing, *new, **curr;
  90
  91         existing = find_option(*opt_list, option->code);
  92         if (!existing) {
  93                 DEBUG("Attaching option %02x to list", option->code);
  94
  95 #if ENABLE_FEATURE_RFC3397
  96                 if ((option->flags & TYPE_MASK) == OPTION_STR1035)
  97                         /* reuse buffer and length for RFC1035-formatted string */
  98                         buffer = dname_enc(NULL, 0, buffer, &length);
  99 #endif
 100
 101                 /* make a new option */
 102                 new = xmalloc(sizeof(*new));
 103                 new->data = xmalloc(length + 2);
 104                 new->data[OPT_CODE] = option->code;
 105                 new->data[OPT_LEN] = length;
 106                 memcpy(new->data + 2, buffer, length);
 107
 108                 curr = opt_list;
 109                 while (*curr && (*curr)->data[OPT_CODE] < option->code)
 110                         curr = &(*curr)->next;
 111
 112                 new->next = *curr;
 113                 *curr = new;
 114 #if ENABLE_FEATURE_RFC3397
 115                 if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 116                         free(buffer);
 117 #endif
 118                 return;
 119         }
 120
 121         /* add it to an existing option */
 122         DEBUG("Attaching option %02x to existing member of list", option->code);
 123         if (option->flags & OPTION_LIST) {
 124 #if ENABLE_FEATURE_RFC3397
 125                 if ((option->flags & TYPE_MASK) == OPTION_STR1035)
 126                         /* reuse buffer and length for RFC1035-formatted string */
 127                         buffer = dname_enc(existing->data + 2,
 128                                         existing->data[OPT_LEN], buffer, &length);
 129 #endif
 130                 if (existing->data[OPT_LEN] + length <= 255) {
 131                         existing->data = xrealloc(existing->data,
 132                                         existing->data[OPT_LEN] + length + 3);
 133                         if ((option->flags & TYPE_MASK) == OPTION_STRING) {
 134                                 /* ' ' can bring us to 256 - bad */
 135                                 if (existing->data[OPT_LEN] + length >= 255)
 136                                         return;
 137                                 /* add space separator between STRING options in a list */
 138                                 existing->data[existing->data[OPT_LEN] + 2] = ' ';
 139                                 existing->data[OPT_LEN]++;
 140                         }
 141                         memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
 142                         existing->data[OPT_LEN] += length;
 143                 } /* else, ignore the data, we could put this in a second option in the future */
 144 #if ENABLE_FEATURE_RFC3397
 145                 if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
 146                         free(buffer);
 147 #endif
 148         } /* else, ignore the new data */
 149 }
 150
 151
 152 /* read a dhcp option and add it to opt_list */
 153 static int 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] __attribute__((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 we'll actually get 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) break;
 179                 length = dhcp_option_lengths[option->flags & TYPE_MASK];
 180                 retval = 0;
 181                 opt = buffer; /* new meaning for variable opt */
 182                 switch (option->flags & TYPE_MASK) {
 183                 case OPTION_IP:
 184                         retval = read_ip(val, buffer);
 185                         break;
 186                 case OPTION_IP_PAIR:
 187                         retval = read_ip(val, buffer);
 188                         val = strtok(NULL, ", \t/-");
 189                         if (!val)
 190                                 retval = 0;
 191                         if (retval)
 192                                 retval = read_ip(val, buffer + 4);
 193                         break;
 194                 case OPTION_STRING:
 195 #if ENABLE_FEATURE_RFC3397
 196                 case OPTION_STR1035:
 197 #endif
 198                         length = strlen(val);
 199                         if (length > 0) {
 200                                 if (length > 254) length = 254;
 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 read_staticlease(const char *const_line, void *arg)
 249 {
 250         char *line;
 251         char *mac_string;
 252         char *ip_string;
 253         uint8_t *mac_bytes;
 254         uint32_t *ip;
 255
 256         /* Allocate memory for addresses */
 257         mac_bytes = xmalloc(sizeof(unsigned char) * 8);
 258         ip = xmalloc(sizeof(uint32_t));
 259
 260         /* Read mac */
 261         line = (char *) const_line;
 262         mac_string = strtok(line, " \t");
 263         read_mac(mac_string, mac_bytes);
 264
 265         /* Read ip */
 266         ip_string = strtok(NULL, " \t");
 267         read_ip(ip_string, ip);
 268
 269         addStaticLease(arg, mac_bytes, ip);
 270
 271         if (ENABLE_FEATURE_UDHCP_DEBUG) printStaticLeases(arg);
 272
 273         return 1;
 274 }
 275
 276
 277 struct config_keyword {
 278         const char *keyword;
 279         int (*handler)(const char *line, void *var);
 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_ip,  &(server_config.start_ip),     "192.168.0.20"},
 287         {"end",          read_ip,  &(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         {"remaining",    read_yn,  &(server_config.remaining),    "yes"},
 293         {"auto_time",    read_u32, &(server_config.auto_time),    "7200"},
 294         {"decline_time", read_u32, &(server_config.decline_time), "3600"},
 295         {"conflict_time",read_u32, &(server_config.conflict_time),"3600"},
 296         {"offer_time",   read_u32, &(server_config.offer_time),   "60"},
 297         {"min_lease",    read_u32, &(server_config.min_lease),    "60"},
 298         {"lease_file",   read_str, &(server_config.lease_file),   LEASES_FILE},
 299         {"pidfile",      read_str, &(server_config.pidfile),      "/var/run/udhcpd.pid"},
 300         {"siaddr",       read_ip,  &(server_config.siaddr),       "0.0.0.0"},
 301         /* keywords with no defaults must be last! */
 302         {"option",       read_opt, &(server_config.options),      ""},
 303         {"opt",          read_opt, &(server_config.options),      ""},
 304         {"notify_file",  read_str, &(server_config.notify_file),  ""},
 305         {"sname",        read_str, &(server_config.sname),        ""},
 306         {"boot_file",    read_str, &(server_config.boot_file),    ""},
 307         {"static_lease", read_staticlease, &(server_config.static_leases), ""},
 308         /* ADDME: static lease */
 309 };
 310 enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
 311
 312
 313 /*
 314  * Domain names may have 254 chars, and string options can be 254
 315  * chars long. However, 80 bytes will be enough for most, and won't
 316  * hog up memory. If you have a special application, change it
 317  */
 318 #define READ_CONFIG_BUF_SIZE 80
 319
 320 void read_config(const char *file)
 321 {
 322         FILE *in;
 323         char buffer[READ_CONFIG_BUF_SIZE], *token, *line;
 324         int i, lineno;
 325
 326         for (i = 0; i < KWS_WITH_DEFAULTS; i++)
 327                 keywords[i].handler(keywords[i].def, keywords[i].var);
 328
 329         in = fopen_or_warn(file, "r");
 330         if (!in)
 331                 return;
 332
 333         lineno = 0;
 334         while (fgets(buffer, READ_CONFIG_BUF_SIZE, in)) {
 335                 lineno++;
 336                 /* *strchrnul(buffer, '\n') = '\0'; - trim() will do it */
 337                 *strchrnul(buffer, '#') = '\0';
 338
 339                 token = strtok(buffer, " \t");
 340                 if (!token) continue;
 341                 line = strtok(NULL, "");
 342                 if (!line) continue;
 343
 344                 trim(line); /* remove leading/trailing whitespace */
 345
 346                 for (i = 0; i < ARRAY_SIZE(keywords); i++) {
 347                         if (!strcasecmp(token, keywords[i].keyword)) {
 348                                 if (!keywords[i].handler(line, keywords[i].var)) {
 349                                         bb_error_msg("can't parse line %d in %s at '%s'",
 350                                                         lineno, file, line);
 351                                         /* reset back to the default value */
 352                                         keywords[i].handler(keywords[i].def, keywords[i].var);
 353                                 }
 354                                 break;
 355                         }
 356                 }
 357         }
 358         fclose(in);
 359
 360         server_config.start_ip = ntohl(server_config.start_ip);
 361         server_config.end_ip = ntohl(server_config.end_ip);
 362 }
 363
 364
 365 void write_leases(void)
 366 {
 367         int fp;
 368         unsigned i;
 369         time_t curr = time(0);
 370         unsigned long tmp_time;
 371
 372         fp = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
 373         if (fp < 0) {
 374                 return;
 375         }
 376
 377         for (i = 0; i < server_config.max_leases; i++) {
 378                 if (leases[i].yiaddr != 0) {
 379
 380                         /* screw with the time in the struct, for easier writing */
 381                         tmp_time = leases[i].expires;
 382
 383                         if (server_config.remaining) {
 384                                 if (lease_expired(&(leases[i])))
 385                                         leases[i].expires = 0;
 386                                 else leases[i].expires -= curr;
 387                         } /* else stick with the time we got */
 388                         leases[i].expires = htonl(leases[i].expires);
 389                         // FIXME: error check??
 390                         full_write(fp, &leases[i], sizeof(leases[i]));
 391
 392                         /* then restore it when done */
 393                         leases[i].expires = tmp_time;
 394                 }
 395         }
 396         close(fp);
 397
 398         if (server_config.notify_file) {
 399                 char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
 400                 system(cmd);
 401                 free(cmd);
 402         }
 403 }
 404
 405
 406 void read_leases(const char *file)
 407 {
 408         int fp;
 409         unsigned int i = 0;
 410         struct dhcpOfferedAddr lease;
 411
 412         fp = open_or_warn(file, O_RDONLY);
 413         if (fp < 0) {
 414                 return;
 415         }
 416
 417         while (i < server_config.max_leases
 418          && full_read(fp, &lease, sizeof(lease)) == sizeof(lease)
 419         ) {
 420                 /* ADDME: is it a static lease */
 421                 uint32_t y = ntohl(lease.yiaddr);
 422                 if (y >= server_config.start_ip && y <= server_config.end_ip) {
 423                         lease.expires = ntohl(lease.expires);
 424                         if (!server_config.remaining)
 425                                 lease.expires -= time(0);
 426                         if (!(add_lease(lease.chaddr, lease.yiaddr, lease.expires))) {
 427                                 bb_error_msg("too many leases while loading %s", file);
 428                                 break;
 429                         }
 430                         i++;
 431                 }
 432         }
 433         DEBUG("Read %d leases", i);
 434         close(fp);
 435 }