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 {"ntpsrv", OPTION_IP | OPTION_LIST, 0x2a}, 38 {"wins", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2c}, 39 {"requestip", OPTION_IP, 0x32}, 40 {"lease", OPTION_U32, 0x33}, 41 {"dhcptype", OPTION_U8, 0x35}, 42 {"serverid", OPTION_IP, 0x36}, 43 {"message", OPTION_STRING, 0x38}, 44 {"tftp", OPTION_STRING, 0x42}, 45 {"bootfile", OPTION_STRING, 0x43}, 46 {"", 0x00, 0x00} 47}; 48 49/* Lengths of the different option types */ 50int option_lengths[] = { 51 [OPTION_IP] = 4, 52 [OPTION_IP_PAIR] = 8, 53 [OPTION_BOOLEAN] = 1, 54 [OPTION_STRING] = 1, 55 [OPTION_U8] = 1, 56 [OPTION_U16] = 2, 57 [OPTION_S16] = 2, 58 [OPTION_U32] = 4, 59 [OPTION_S32] = 4 60}; 61 62 63/* get an option with bounds checking (warning, not aligned). */ 64unsigned char *get_option(struct dhcpMessage *packet, int code) 65{ 66 int i, length; 67 unsigned char *optionptr; 68 int over = 0, done = 0, curr = OPTION_FIELD; 69 70 optionptr = packet->options; 71 i = 0; 72 length = 308; 73 while (!done) { 74 if (i >= length) { 75 LOG(LOG_WARNING, "bogus packet, option fields too long."); 76 return NULL; 77 } 78 if (optionptr[i + OPT_CODE] == code) { 79 if (i + 1 + optionptr[i + OPT_LEN] >= length) { 80 LOG(LOG_WARNING, "bogus packet, option fields too long."); 81 return NULL; 82 } 83 return optionptr + i + 2; 84 } 85 switch (optionptr[i + OPT_CODE]) { 86 case DHCP_PADDING: 87 i++; 88 break; 89 case DHCP_OPTION_OVER: 90 if (i + 1 + optionptr[i + OPT_LEN] >= length) { 91 LOG(LOG_WARNING, "bogus packet, option fields too long."); 92 return NULL; 93 } 94 over = optionptr[i + 3]; 95 i += optionptr[OPT_LEN] + 2; 96 break; 97 case DHCP_END: 98 if (curr == OPTION_FIELD && over & FILE_FIELD) { 99 optionptr = packet->file; 100 i = 0; 101 length = 128; 102 curr = FILE_FIELD; 103 } else if (curr == FILE_FIELD && over & SNAME_FIELD) { 104 optionptr = packet->sname; 105 i = 0; 106 length = 64; 107 curr = SNAME_FIELD; 108 } else done = 1; 109 break; 110 default: 111 i += optionptr[OPT_LEN + i] + 2; 112 } 113 } 114 return NULL; 115} 116 117 118/* return the position of the 'end' option (no bounds checking) */ 119int end_option(unsigned char *optionptr) 120{ 121 int i = 0; 122 123 while (optionptr[i] != DHCP_END) { 124 if (optionptr[i] == DHCP_PADDING) i++; 125 else i += optionptr[i + OPT_LEN] + 2; 126 } 127 return i; 128} 129 130 131/* add an option string to the options (an option string contains an option code, 132 * length, then data) */ 133int add_option_string(unsigned char *optionptr, unsigned char *string) 134{ 135 int end = end_option(optionptr); 136 137 /* end position + string length + option code/length + end option */ 138 if (end + string[OPT_LEN] + 2 + 1 >= 308) { 139 LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]); 140 return 0; 141 } 142 DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]); 143 memcpy(optionptr + end, string, string[OPT_LEN] + 2); 144 optionptr[end + string[OPT_LEN] + 2] = DHCP_END; 145 return string[OPT_LEN] + 2; 146} 147 148 149/* add a one to four byte option to a packet */ 150int add_simple_option(unsigned char *optionptr, unsigned char code, u_int32_t data) 151{ 152 char length = 0; 153 int i; 154 unsigned char option[2 + 4]; 155 unsigned char *u8; 156 u_int16_t *u16; 157 u_int32_t *u32; 158 u_int32_t aligned; 159 u8 = (unsigned char *) &aligned; 160 u16 = (u_int16_t *) (void *)&aligned; 161 u32 = &aligned; 162 163 for (i = 0; options[i].code; i++) 164 if (options[i].code == code) { 165 length = option_lengths[options[i].flags & TYPE_MASK]; 166 } 167 168 if (!length) { 169 DEBUG(LOG_ERR, "Could not add option 0x%02x", code); 170 return 0; 171 } 172 173 option[OPT_CODE] = code; 174 option[OPT_LEN] = length; 175 176 switch (length) { 177 case 1: *u8 = data; break; 178 case 2: *u16 = data; break; 179 case 4: *u32 = data; break; 180 } 181 memcpy(option + 2, &aligned, length); 182 return add_option_string(optionptr, option); 183} 184 185 186/* find option 'code' in opt_list */ 187struct option_set *find_option(struct option_set *opt_list, char code) 188{ 189 while (opt_list && opt_list->data[OPT_CODE] < code) 190 opt_list = opt_list->next; 191 192 if (opt_list && opt_list->data[OPT_CODE] == code) return opt_list; 193 else return NULL; 194} 195 196 197/* add an option to the opt_list */ 198void attach_option(struct option_set **opt_list, struct dhcp_option *option, char *buffer, int length) 199{ 200 struct option_set *existing, *new, **curr; 201 202 /* add it to an existing option */ 203 if ((existing = find_option(*opt_list, option->code))) { 204 DEBUG(LOG_INFO, "Attaching option %s to existing member of list", option->name); 205 if (option->flags & OPTION_LIST) { 206 if (existing->data[OPT_LEN] + length <= 255) { 207 existing->data = realloc(existing->data, 208 existing->data[OPT_LEN] + length + 2); 209 memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length); 210 existing->data[OPT_LEN] += length; 211 } /* else, ignore the data, we could put this in a second option in the future */ 212 } /* else, ignore the new data */ 213 } else { 214 DEBUG(LOG_INFO, "Attaching option %s to list", option->name); 215 216 /* make a new option */ 217 new = malloc(sizeof(struct option_set)); 218 new->data = malloc(length + 2); 219 new->data[OPT_CODE] = option->code; 220 new->data[OPT_LEN] = length; 221 memcpy(new->data + 2, buffer, length); 222 223 curr = opt_list; 224 while (*curr && (*curr)->data[OPT_CODE] < option->code) 225 curr = &(*curr)->next; 226 227 new->next = *curr; 228 *curr = new; 229 } 230} 231