git.maemo.org Git - udhcp/blob - options.c

   1 /*
   2  * options.c -- DHCP server option packet tools
   3  * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
   4  */
   5
   6 #include <stdlib.h>
   7 #include <string.h>
   8
   9 #include "dhcpd.h"
  10 #include "files.h"
  11 #include "options.h"
  12 #include "common.h"
  13
  14
  15 /* supported options are easily added here */
  16 struct dhcp_option dhcp_options[] = {
  17         /* name[10]     flags                                   code */
  18         {"subnet",      OPTION_IP | OPTION_REQ,                 0x01},
  19         {"timezone",    OPTION_S32,                             0x02},
  20         {"router",      OPTION_IP | OPTION_LIST | OPTION_REQ,   0x03},
  21         {"timesvr",     OPTION_IP | OPTION_LIST,                0x04},
  22         {"namesvr",     OPTION_IP | OPTION_LIST,                0x05},
  23         {"dns",         OPTION_IP | OPTION_LIST | OPTION_REQ,   0x06},
  24         {"logsvr",      OPTION_IP | OPTION_LIST,                0x07},
  25         {"cookiesvr",   OPTION_IP | OPTION_LIST,                0x08},
  26         {"lprsvr",      OPTION_IP | OPTION_LIST,                0x09},
  27         {"hostname",    OPTION_STRING | OPTION_REQ,             0x0c},
  28         {"bootsize",    OPTION_U16,                             0x0d},
  29         {"domain",      OPTION_STRING | OPTION_REQ,             0x0f},
  30         {"swapsvr",     OPTION_IP,                              0x10},
  31         //We had the possibility for the client to ask for a rootpath
  32         //closes http://bugs.debian.org/279110 (ericvb@debian.org)
  33         //{"rootpath",  OPTION_STRING,                          0x11},
  34         {"rootpath",    OPTION_STRING | OPTION_REQ,             0x11},
  35         {"ipttl",       OPTION_U8,                              0x17},
  36         {"mtu",         OPTION_U16,                             0x1a},
  37         {"broadcast",   OPTION_IP | OPTION_REQ,                 0x1c},
  38         {"nisdomain",   OPTION_STRING | OPTION_REQ,             0x28},
  39         {"nissrv",      OPTION_IP | OPTION_LIST | OPTION_REQ,   0x29},
  40         {"ntpsrv",      OPTION_IP | OPTION_LIST | OPTION_REQ,   0x2a},
  41         {"wins",        OPTION_IP | OPTION_LIST,                0x2c},
  42         {"requestip",   OPTION_IP,                              0x32},
  43         {"lease",       OPTION_U32,                             0x33},
  44         {"dhcptype",    OPTION_U8,                              0x35},
  45         {"serverid",    OPTION_IP,                              0x36},
  46         {"message",     OPTION_STRING,                          0x38},
  47         {"tftp",        OPTION_STRING,                          0x42},
  48         {"bootfile",    OPTION_STRING,                          0x43},
  49         {"wpad",        OPTION_STRING,                          0xfc},
  50         {"",            0x00,                           0x00}
  51 };
  52
  53 /* Lengths of the different option types */
  54 int option_lengths[] = {
  55         [OPTION_IP] =           4,
  56         [OPTION_IP_PAIR] =      8,
  57         [OPTION_BOOLEAN] =      1,
  58         [OPTION_STRING] =       1,
  59         [OPTION_U8] =           1,
  60         [OPTION_U16] =          2,
  61         [OPTION_S16] =          2,
  62         [OPTION_U32] =          4,
  63         [OPTION_S32] =          4
  64 };
  65
  66
  67 /* get an option with bounds checking (warning, not aligned). */
  68 uint8_t *get_option(struct dhcpMessage *packet, int code)
  69 {
  70         int i, length;
  71         uint8_t *optionptr;
  72         int over = 0, done = 0, curr = OPTION_FIELD;
  73
  74         optionptr = packet->options;
  75         i = 0;
  76         length = 308;
  77         while (!done) {
  78                 if (i >= length) {
  79                         LOG(LOG_WARNING, "bogus packet, option fields too long.");
  80                         return NULL;
  81                 }
  82                 if (optionptr[i + OPT_CODE] == code) {
  83                         if (i + 1 + optionptr[i + OPT_LEN] >= length) {
  84                                 LOG(LOG_WARNING, "bogus packet, option fields too long.");
  85                                 return NULL;
  86                         }
  87                         return optionptr + i + 2;
  88                 }
  89                 switch (optionptr[i + OPT_CODE]) {
  90                 case DHCP_PADDING:
  91                         i++;
  92                         break;
  93                 case DHCP_OPTION_OVER:
  94                         if (i + 1 + optionptr[i + OPT_LEN] >= length) {
  95                                 LOG(LOG_WARNING, "bogus packet, option fields too long.");
  96                                 return NULL;
  97                         }
  98                         over = optionptr[i + 3];
  99                         i += optionptr[OPT_LEN] + 2;
 100                         break;
 101                 case DHCP_END:
 102                         if (curr == OPTION_FIELD && over & FILE_FIELD) {
 103                                 optionptr = packet->file;
 104                                 i = 0;
 105                                 length = 128;
 106                                 curr = FILE_FIELD;
 107                         } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
 108                                 optionptr = packet->sname;
 109                                 i = 0;
 110                                 length = 64;
 111                                 curr = SNAME_FIELD;
 112                         } else done = 1;
 113                         break;
 114                 default:
 115                         i += optionptr[OPT_LEN + i] + 2;
 116                 }
 117         }
 118         return NULL;
 119 }
 120
 121
 122 /* return the position of the 'end' option (no bounds checking) */
 123 int end_option(uint8_t *optionptr)
 124 {
 125         int i = 0;
 126
 127         while (optionptr[i] != DHCP_END) {
 128                 if (optionptr[i] == DHCP_PADDING) i++;
 129                 else i += optionptr[i + OPT_LEN] + 2;
 130         }
 131         return i;
 132 }
 133
 134
 135 /* add an option string to the options (an option string contains an option code,
 136  * length, then data) */
 137 int add_option_string(uint8_t *optionptr, uint8_t *string)
 138 {
 139         int end = end_option(optionptr);
 140
 141         /* end position + string length + option code/length + end option */
 142         if (end + string[OPT_LEN] + 2 + 1 >= 308) {
 143                 LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]);
 144                 return 0;
 145         }
 146         DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]);
 147         memcpy(optionptr + end, string, string[OPT_LEN] + 2);
 148         optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
 149         return string[OPT_LEN] + 2;
 150 }
 151
 152
 153 /* add a one to four byte option to a packet */
 154 int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
 155 {
 156         char length = 0;
 157         int i;
 158         uint8_t option[2 + 4];
 159         uint8_t *u8;
 160         uint16_t *u16;
 161         uint32_t *u32;
 162         uint32_t aligned;
 163         u8 = (uint8_t *) &aligned;
 164         u16 = (uint16_t *) &aligned;
 165         u32 = &aligned;
 166
 167         for (i = 0; dhcp_options[i].code; i++)
 168                 if (dhcp_options[i].code == code) {
 169                         length = option_lengths[dhcp_options[i].flags & TYPE_MASK];
 170                 }
 171
 172         if (!length) {
 173                 DEBUG(LOG_ERR, "Could not add option 0x%02x", code);
 174                 return 0;
 175         }
 176
 177         option[OPT_CODE] = code;
 178         option[OPT_LEN] = length;
 179
 180         switch (length) {
 181                 case 1: *u8 =  data; break;
 182                 case 2: *u16 = data; break;
 183                 case 4: *u32 = data; break;
 184         }
 185         memcpy(option + 2, &aligned, length);
 186         return add_option_string(optionptr, option);
 187 }
 188
 189
 190 /* find option 'code' in opt_list */
 191 struct option_set *find_option(struct option_set *opt_list, char code)
 192 {
 193         while (opt_list && opt_list->data[OPT_CODE] < code)
 194                 opt_list = opt_list->next;
 195
 196         if (opt_list && opt_list->data[OPT_CODE] == code) return opt_list;
 197         else return NULL;
 198 }
 199
 200
 201 /* add an option to the opt_list */
 202 void attach_option(struct option_set **opt_list, struct dhcp_option *option, char *buffer, int length)
 203 {
 204         struct option_set *existing, *new, **curr;
 205
 206         /* add it to an existing option */
 207         if ((existing = find_option(*opt_list, option->code))) {
 208                 DEBUG(LOG_INFO, "Attaching option %s to existing member of list", option->name);
 209                 if (option->flags & OPTION_LIST) {
 210                         if (existing->data[OPT_LEN] + length <= 255) {
 211                                 existing->data = realloc(existing->data,
 212                                                 existing->data[OPT_LEN] + length + 2);
 213                                 memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
 214                                 existing->data[OPT_LEN] += length;
 215                         } /* else, ignore the data, we could put this in a second option in the future */
 216                 } /* else, ignore the new data */
 217         } else {
 218                 DEBUG(LOG_INFO, "Attaching option %s to list", option->name);
 219
 220                 /* make a new option */
 221                 new = xmalloc(sizeof(struct option_set));
 222                 new->data = xmalloc(length + 2);
 223                 new->data[OPT_CODE] = option->code;
 224                 new->data[OPT_LEN] = length;
 225                 memcpy(new->data + 2, buffer, length);
 226
 227                 curr = opt_list;
 228                 while (*curr && (*curr)->data[OPT_CODE] < option->code)
 229                         curr = &(*curr)->next;
 230
 231                 new->next = *curr;
 232                 *curr = new;
 233         }
 234 }