1 /* vi: set sw=4 ts=4: */
3 * options.c -- DHCP server option packet tools
4 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
12 /* Supported options are easily added here */
13 const struct dhcp_option dhcp_options[] = {
14 /* opt_name[12] flags code */
15 {"subnet", OPTION_IP | OPTION_REQ, 0x01}, /* DHCP_SUBNET */
16 {"timezone", OPTION_S32, 0x02}, /* DHCP_TIME_OFFSET */
17 {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03}, /* DHCP_ROUTER */
18 {"timesvr", OPTION_IP | OPTION_LIST, 0x04}, /* DHCP_TIME_SERVER */
19 {"namesvr", OPTION_IP | OPTION_LIST, 0x05}, /* DHCP_NAME_SERVER */
20 {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06}, /* DHCP_DNS_SERVER */
21 {"logsvr", OPTION_IP | OPTION_LIST, 0x07}, /* DHCP_LOG_SERVER */
22 {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08}, /* DHCP_COOKIE_SERVER */
23 {"lprsvr", OPTION_IP | OPTION_LIST, 0x09}, /* DHCP_LPR_SERVER */
24 {"hostname", OPTION_STRING | OPTION_REQ, 0x0c}, /* DHCP_HOST_NAME */
25 {"bootsize", OPTION_U16, 0x0d}, /* DHCP_BOOT_SIZE */
26 {"domain", OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x0f}, /* DHCP_DOMAIN_NAME */
27 {"swapsvr", OPTION_IP, 0x10}, /* DHCP_SWAP_SERVER */
28 {"rootpath", OPTION_STRING, 0x11}, /* DHCP_ROOT_PATH */
29 {"ipttl", OPTION_U8, 0x17}, /* DHCP_IP_TTL */
30 {"mtu", OPTION_U16, 0x1a}, /* DHCP_MTU */
31 {"broadcast", OPTION_IP | OPTION_REQ, 0x1c}, /* DHCP_BROADCAST */
32 {"nisdomain", OPTION_STRING | OPTION_REQ, 0x28}, /* DHCP_NTP_SERVER */
33 {"nissrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x29}, /* DHCP_WINS_SERVER */
34 {"ntpsrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a}, /* DHCP_REQUESTED_IP */
35 {"wins", OPTION_IP | OPTION_LIST, 0x2c}, /* DHCP_LEASE_TIME */
36 {"requestip", OPTION_IP, 0x32}, /* DHCP_OPTION_OVER */
37 {"lease", OPTION_U32, 0x33}, /* DHCP_MESSAGE_TYPE */
38 {"dhcptype", OPTION_U8, 0x35}, /* DHCP_SERVER_ID */
39 {"serverid", OPTION_IP, 0x36}, /* DHCP_PARAM_REQ */
40 {"message", OPTION_STRING, 0x38}, /* DHCP_MESSAGE */
41 // TODO: 1) some options should not be parsed & passed to script -
42 // maxsize sure should not, since it cannot appear in server responses!
43 // grep for opt_name is fix the mess.
44 // 2) Using fixed-sized char[] vector wastes space.
45 {"maxsize", OPTION_U16, 0x39}, /* DHCP_MAX_SIZE */
46 {"vendorclass", OPTION_STRING, 0x3C}, /* DHCP_VENDOR */
47 {"clientid", OPTION_STRING, 0x3D}, /* DHCP_CLIENT_ID */
48 {"tftp", OPTION_STRING, 0x42},
49 {"bootfile", OPTION_STRING, 0x43},
50 {"userclass", OPTION_STRING, 0x4D},
51 #if ENABLE_FEATURE_RFC3397
52 {"search", OPTION_STR1035 | OPTION_LIST | OPTION_REQ, 0x77},
54 /* MSIE's "Web Proxy Autodiscovery Protocol" support */
55 {"wpad", OPTION_STRING, 0xfc},
56 {} /* zero-padded terminating entry */
60 /* Lengths of the different option types */
61 const unsigned char option_lengths[] ALIGN1 = {
66 #if ENABLE_FEATURE_RFC3397
77 /* get an option with bounds checking (warning, not aligned). */
78 uint8_t *get_option(struct dhcpMessage *packet, int code)
83 int curr = OPTION_FIELD;
85 optionptr = packet->options;
87 length = sizeof(packet->options);
90 bb_error_msg("bogus packet, option fields too long");
93 if (optionptr[i + OPT_CODE] == code) {
94 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
95 bb_error_msg("bogus packet, option fields too long");
98 return optionptr + i + 2;
100 switch (optionptr[i + OPT_CODE]) {
104 case DHCP_OPTION_OVER:
105 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
106 bb_error_msg("bogus packet, option fields too long");
109 over = optionptr[i + 3];
110 i += optionptr[OPT_LEN] + 2;
113 if (curr == OPTION_FIELD && (over & FILE_FIELD)) {
114 optionptr = packet->file;
116 length = sizeof(packet->file);
118 } else if (curr == FILE_FIELD && (over & SNAME_FIELD)) {
119 optionptr = packet->sname;
121 length = sizeof(packet->sname);
127 i += optionptr[OPT_LEN + i] + 2;
134 /* return the position of the 'end' option (no bounds checking) */
135 int end_option(uint8_t *optionptr)
139 while (optionptr[i] != DHCP_END) {
140 if (optionptr[i] == DHCP_PADDING) i++;
141 else i += optionptr[i + OPT_LEN] + 2;
147 /* add an option string to the options (an option string contains an option code,
148 * length, then data) */
149 int add_option_string(uint8_t *optionptr, uint8_t *string)
151 int end = end_option(optionptr);
153 /* end position + string length + option code/length + end option */
154 if (end + string[OPT_LEN] + 2 + 1 >= DHCP_OPTIONS_BUFSIZE) {
155 bb_error_msg("option 0x%02x did not fit into the packet",
159 DEBUG("adding option 0x%02x", string[OPT_CODE]);
160 memcpy(optionptr + end, string, string[OPT_LEN] + 2);
161 optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
162 return string[OPT_LEN] + 2;
166 /* add a one to four byte option to a packet */
167 int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
169 const struct dhcp_option *dh;
171 for (dh = dhcp_options; dh->code; dh++) {
172 if (dh->code == code) {
173 uint8_t option[6], len;
175 option[OPT_CODE] = code;
176 len = option_lengths[dh->flags & TYPE_MASK];
177 option[OPT_LEN] = len;
178 if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);
179 /* This memcpy is for broken processors which can't
180 * handle a simple unaligned 32-bit assignment */
181 memcpy(&option[OPT_DATA], &data, 4);
182 return add_option_string(optionptr, option);
186 bb_error_msg("cannot add option 0x%02x", code);