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 {"routes", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x21}, 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 {"max-size", OPTION_U16, 0x39}, 46 {"tftp", OPTION_STRING, 0x42}, 47 {"bootfile", OPTION_STRING, 0x43}, 48 {"msroutes", OPTION_U8 | OPTION_LIST | OPTION_REQ, 0xF9}, 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 length = 308; 76 while (!done) { 77 if (i >= length) { 78 LOG(LOG_WARNING, "bogus packet, option fields too long."); 79 return NULL; 80 } 81 if (optionptr[i + OPT_CODE] == code) { 82 if (i + 1 + optionptr[i + OPT_LEN] >= length) { 83 LOG(LOG_WARNING, "bogus packet, option fields too long."); 84 return NULL; 85 } 86 return optionptr + i + 2; 87 } 88 switch (optionptr[i + OPT_CODE]) { 89 case DHCP_PADDING: 90 i++; 91 break; 92 case DHCP_OPTION_OVER: 93 if (i + 1 + optionptr[i + OPT_LEN] >= length) { 94 LOG(LOG_WARNING, "bogus packet, option fields too long."); 95 return NULL; 96 } 97 over = optionptr[i + 3]; 98 i += optionptr[OPT_LEN] + 2; 99 break; 100 case DHCP_END: 101 if (curr == OPTION_FIELD && over & FILE_FIELD) { 102 optionptr = packet->file; 103 i = 0; 104 length = 128; 105 curr = FILE_FIELD; 106 } else if (curr == FILE_FIELD && over & SNAME_FIELD) { 107 optionptr = packet->sname; 108 i = 0; 109 length = 64; 110 curr = SNAME_FIELD; 111 } else done = 1; 112 break; 113 default: 114 i += optionptr[OPT_LEN + i] + 2; 115 } 116 } 117 return NULL; 118} 119 120 121/* return the position of the 'end' option (no bounds checking) */ 122int end_option(unsigned char *optionptr) 123{ 124 int i = 0; 125 126 while (optionptr[i] != DHCP_END) { 127 if (optionptr[i] == DHCP_PADDING) i++; 128 else i += optionptr[i + OPT_LEN] + 2; 129 } 130 return i; 131} 132 133 134/* add an option string to the options (an option string contains an option code, 135 * length, then data) */ 136int add_option_string(unsigned char *optionptr, unsigned char *string) 137{ 138 int end = end_option(optionptr); 139 140 /* end position + string length + option code/length + end option */ 141 if (end + string[OPT_LEN] + 2 + 1 >= 308) { 142 LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]); 143 return 0; 144 } 145 DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]); 146 memcpy(optionptr + end, string, string[OPT_LEN] + 2); 147 optionptr[end + string[OPT_LEN] + 2] = DHCP_END; 148 return string[OPT_LEN] + 2; 149} 150 151 152/* add a one to four byte option to a packet */ 153int add_simple_option(unsigned char *optionptr, unsigned char code, u_int32_t data) 154{ 155 char length = 0; 156 int i; 157 unsigned char option[2 + 4]; 158 unsigned char *u8; 159 u_int16_t *u16; 160 u_int32_t *u32; 161 u_int32_t aligned; 162 u8 = (unsigned char *) &aligned; 163 u16 = (u_int16_t *) &aligned; 164 u32 = &aligned; 165 166 for (i = 0; options[i].code; i++) 167 if (options[i].code == code) { 168 length = option_lengths[options[i].flags & TYPE_MASK]; 169 } 170 171 if (!length) { 172 DEBUG(LOG_ERR, "Could not add option 0x%02x", code); 173 return 0; 174 } 175 176 option[OPT_CODE] = code; 177 option[OPT_LEN] = length; 178 179 switch (length) { 180 case 1: *u8 = data; break; 181 case 2: *u16 = data; break; 182 case 4: *u32 = data; break; 183 } 184 memcpy(option + 2, &aligned, length); 185 return add_option_string(optionptr, option); 186} 187 188 189/* find option 'code' in opt_list */ 190struct option_set *find_option(struct option_set *opt_list, char code) 191{ 192 while (opt_list && opt_list->data[OPT_CODE] < code) 193 opt_list = opt_list->next; 194 195 if (opt_list && opt_list->data[OPT_CODE] == code) return opt_list; 196 else return NULL; 197} 198 199 200/* add an option to the opt_list */ 201void attach_option(struct option_set **opt_list, struct dhcp_option *option, char *buffer, int length) 202{ 203 struct option_set *existing, *new, **curr; 204 205 /* add it to an existing option */ 206 if ((existing = find_option(*opt_list, option->code))) { 207 DEBUG(LOG_INFO, "Attaching option %s to existing member of list", option->name); 208 if (option->flags & OPTION_LIST) { 209 if (existing->data[OPT_LEN] + length <= 255) { 210 existing->data = realloc(existing->data, 211 existing->data[OPT_LEN] + length + 2); 212 memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length); 213 existing->data[OPT_LEN] += length; 214 } /* else, ignore the data, we could put this in a second option in the future */ 215 } /* else, ignore the new data */ 216 } else { 217 DEBUG(LOG_INFO, "Attaching option %s to list", option->name); 218 219 /* make a new option */ 220 new = malloc(sizeof(struct option_set)); 221 new->data = malloc(length + 2); 222 new->data[OPT_CODE] = option->code; 223 new->data[OPT_LEN] = length; 224 memcpy(new->data + 2, buffer, length); 225 226 curr = opt_list; 227 while (*curr && (*curr)->data[OPT_CODE] < option->code) 228 curr = &(*curr)->next; 229 230 new->next = *curr; 231 *curr = new; 232 } 233} 234