1/* 2 * options.c -- DHCP server option packet tools 3 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001 4 */ 5 6#include <stdio.h> 7#include <stdlib.h> 8#include <string.h> 9 10#include "debug.h" 11#include "dhcpd.h" 12#include "files.h" 13#include "options.h" 14#include "leases.h" 15 16 17/* supported options are easily added here */ 18struct dhcp_option options[] = { 19 /* name[10] flags code */ 20 {"subnet", OPTION_IP | OPTION_REQ, 0x01}, 21 {"timezone", OPTION_S32, 0x02}, 22 {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03}, 23 {"timesvr", OPTION_IP | OPTION_LIST, 0x04}, 24 {"namesvr", OPTION_IP | OPTION_LIST, 0x05}, 25 {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06}, 26 {"logsvr", OPTION_IP | OPTION_LIST, 0x07}, 27 {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08}, 28 {"lprsvr", OPTION_IP | OPTION_LIST, 0x09}, 29 {"hostname", OPTION_STRING | OPTION_REQ, 0x0c}, 30 {"bootsize", OPTION_U16, 0x0d}, 31 {"domain", OPTION_STRING | OPTION_REQ, 0x0f}, 32 {"swapsvr", OPTION_IP, 0x10}, 33 {"rootpath", OPTION_STRING, 0x11}, 34 {"ipttl", OPTION_U8, 0x17}, 35 {"mtu", OPTION_U16, 0x1a}, 36 {"broadcast", OPTION_IP | OPTION_REQ, 0x1c}, 37 {"sroute", OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x21}, /* static-routes, foxconn added by EricHuang, 03/12/2008 */ 38 {"ntpsrv", OPTION_IP | OPTION_LIST, 0x2a}, 39 {"wins", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2c}, 40 {"requestip", OPTION_IP, 0x32}, 41 {"lease", OPTION_U32, 0x33}, 42 {"dhcptype", OPTION_U8, 0x35}, 43 {"serverid", OPTION_IP, 0x36}, 44 {"message", OPTION_STRING, 0x38}, 45 {"tftp", OPTION_STRING, 0x42}, 46 {"bootfile", OPTION_STRING, 0x43}, 47 {"rfc3442", OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x79}, /* classless-static-routes, foxconn added by EricHuang, 12/20/2007 */ 48 {"rfc3442", OPTION_STRING | OPTION_LIST | OPTION_REQ, 0xf9}, /* foxconn added, 03/08/2010, @option249 */ 49 {"", 0x00, 0x00} 50}; 51 52/* Lengths of the different option types */ 53int option_lengths[] = { 54 [OPTION_IP] = 4, 55 [OPTION_IP_PAIR] = 8, 56 [OPTION_BOOLEAN] = 1, 57 [OPTION_STRING] = 1, 58 [OPTION_U8] = 1, 59 [OPTION_U16] = 2, 60 [OPTION_S16] = 2, 61 [OPTION_U32] = 4, 62 [OPTION_S32] = 4 63}; 64 65 66/* get an option with bounds checking (warning, not aligned). */ 67unsigned char *get_option(struct dhcpMessage *packet, int code) 68{ 69 int i, length; 70 unsigned char *optionptr; 71 int over = 0, done = 0, curr = OPTION_FIELD; 72 73 optionptr = packet->options; 74 i = 0; 75 /* foxconn modified start, zacker, 09/18/2009, @big_size_pkt */ 76 //length = 308; 77 /* Foxconn modified start pling 05/11/2012 */ 78 /* Fix a DHCP server crash issue: 79 * DHCP server packet was not modified to receive large size packet. 80 * So we only check options for LEN_OPTIONS long. 81 */ 82 if (packet->op == BOOTREQUEST) 83 length = LEN_OPTIONS; 84 else 85 length = LEN_OPTIONS + LEN_PADDING; 86 /* Foxconn modified end pling 05/11/2012 */ 87 /* foxconn modified end, zacker, 09/18/2009, @big_size_pkt */ 88 while (!done) { 89 if (i >= length) { 90 LOG(LOG_WARNING, "bogus packet, option fields too long."); 91 return NULL; 92 } 93 if (optionptr[i + OPT_CODE] == code) { 94 if (i + 1 + optionptr[i + OPT_LEN] >= length) { 95 LOG(LOG_WARNING, "bogus packet, option fields too long."); 96 return NULL; 97 } 98 return optionptr + i + 2; 99 } 100 switch (optionptr[i + OPT_CODE]) { 101 case DHCP_PADDING: 102 i++; 103 break; 104 case DHCP_OPTION_OVER: 105 if (i + 1 + optionptr[i + OPT_LEN] >= length) { 106 LOG(LOG_WARNING, "bogus packet, option fields too long."); 107 return NULL; 108 } 109 over = optionptr[i + 3]; 110 i += optionptr[OPT_LEN] + 2; 111 break; 112 case DHCP_END: 113 if (curr == OPTION_FIELD && over & FILE_FIELD) { 114 optionptr = packet->file; 115 i = 0; 116 length = 128; 117 curr = FILE_FIELD; 118 } else if (curr == FILE_FIELD && over & SNAME_FIELD) { 119 optionptr = packet->sname; 120 i = 0; 121 length = 64; 122 curr = SNAME_FIELD; 123 } else done = 1; 124 break; 125 default: 126 i += optionptr[OPT_LEN + i] + 2; 127 } 128 } 129 return NULL; 130} 131 132 133/* return the position of the 'end' option (no bounds checking) */ 134int end_option(unsigned char *optionptr) 135{ 136 int i = 0; 137 138 while (optionptr[i] != DHCP_END) { 139 if (optionptr[i] == DHCP_PADDING) i++; 140 else i += optionptr[i + OPT_LEN] + 2; 141 } 142 return i; 143} 144 145 146/* add an option string to the options (an option string contains an option code, 147 * length, then data) */ 148int add_option_string(unsigned char *optionptr, unsigned char *string) 149{ 150 int end = end_option(optionptr); 151 152 /* end position + string length + option code/length + end option */ 153 if (end + string[OPT_LEN] + 2 + 1 >= 308) { 154 LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]); 155 return 0; 156 } 157 DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]); 158 memcpy(optionptr + end, string, string[OPT_LEN] + 2); 159 optionptr[end + string[OPT_LEN] + 2] = DHCP_END; 160 return string[OPT_LEN] + 2; 161} 162 163 164/* add a one to four byte option to a packet */ 165int add_simple_option(unsigned char *optionptr, unsigned char code, u_int32_t data) 166{ 167 char length = 0; 168 int i; 169 unsigned char option[2 + 4]; 170 unsigned char *u8; 171 u_int16_t *u16; 172 u_int32_t *u32; 173 u_int32_t aligned; 174 u8 = (unsigned char *) &aligned; 175 u16 = (u_int16_t *) &aligned; 176 u32 = &aligned; 177 178 for (i = 0; options[i].code; i++) 179 if (options[i].code == code) { 180 length = option_lengths[options[i].flags & TYPE_MASK]; 181 } 182 183 if (!length) { 184 DEBUG(LOG_ERR, "Could not add option 0x%02x", code); 185 return 0; 186 } 187 188 option[OPT_CODE] = code; 189 option[OPT_LEN] = length; 190 191 switch (length) { 192 case 1: *u8 = data; break; 193 case 2: *u16 = data; break; 194 case 4: *u32 = data; break; 195 } 196 memcpy(option + 2, &aligned, length); 197 return add_option_string(optionptr, option); 198} 199 200 201/* find option 'code' in opt_list */ 202struct option_set *find_option(struct option_set *opt_list, char code) 203{ 204 while (opt_list && opt_list->data[OPT_CODE] < code) 205 opt_list = opt_list->next; 206 207 if (opt_list && opt_list->data[OPT_CODE] == code) return opt_list; 208 else return NULL; 209} 210 211 212/* add an option to the opt_list */ 213void attach_option(struct option_set **opt_list, struct dhcp_option *option, char *buffer, int length) 214{ 215 struct option_set *existing, *new, **curr; 216 217 /* add it to an existing option */ 218 if ((existing = find_option(*opt_list, option->code))) { 219 DEBUG(LOG_INFO, "Attaching option %s to existing member of list", option->name); 220 if (option->flags & OPTION_LIST) { 221 if (existing->data[OPT_LEN] + length <= 255) { 222 existing->data = realloc(existing->data, 223 existing->data[OPT_LEN] + length + 2); 224 memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length); 225 existing->data[OPT_LEN] += length; 226 } /* else, ignore the data, we could put this in a second option in the future */ 227 } /* else, ignore the new data */ 228 } else { 229 DEBUG(LOG_INFO, "Attaching option %s to list", option->name); 230 231 /* make a new option */ 232 new = malloc(sizeof(struct option_set)); 233 new->data = malloc(length + 2); 234 new->data[OPT_CODE] = option->code; 235 new->data[OPT_LEN] = length; 236 memcpy(new->data + 2, buffer, length); 237 238 curr = opt_list; 239 while (*curr && (*curr)->data[OPT_CODE] < option->code) 240 curr = &(*curr)->next; 241 242 new->next = *curr; 243 *curr = new; 244 } 245} 246