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 /* name[10] flags code */
15 {"subnet", OPTION_IP | OPTION_REQ, 0x01},
16 {"timezone", OPTION_S32, 0x02},
17 {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03},
18 {"timesvr", OPTION_IP | OPTION_LIST, 0x04},
19 {"namesvr", OPTION_IP | OPTION_LIST, 0x05},
20 {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06},
21 {"logsvr", OPTION_IP | OPTION_LIST, 0x07},
22 {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08},
23 {"lprsvr", OPTION_IP | OPTION_LIST, 0x09},
24 {"hostname", OPTION_STRING | OPTION_REQ, 0x0c},
25 {"bootsize", OPTION_U16, 0x0d},
26 {"domain", OPTION_STRING | OPTION_REQ, 0x0f},
27 {"swapsvr", OPTION_IP, 0x10},
28 {"rootpath", OPTION_STRING, 0x11},
29 {"ipttl", OPTION_U8, 0x17},
30 {"mtu", OPTION_U16, 0x1a},
31 {"broadcast", OPTION_IP | OPTION_REQ, 0x1c},
32 {"nisdomain", OPTION_STRING | OPTION_REQ, 0x28},
33 {"nissrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x29},
34 {"ntpsrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a},
35 {"wins", OPTION_IP | OPTION_LIST, 0x2c},
36 {"requestip", OPTION_IP, 0x32},
37 {"lease", OPTION_U32, 0x33},
38 {"dhcptype", OPTION_U8, 0x35},
39 {"serverid", OPTION_IP, 0x36},
40 {"message", OPTION_STRING, 0x38},
41 {"vendorclass", OPTION_STRING, 0x3C},
42 {"clientid", OPTION_STRING, 0x3D},
43 {"tftp", OPTION_STRING, 0x42},
44 {"bootfile", OPTION_STRING, 0x43},
45 {"userclass", OPTION_STRING, 0x4D},
46 /* MSIE's "Web Proxy Autodiscovery Protocol" support */
47 {"wpad", OPTION_STRING, 0xfc},
51 /* Lengths of the different option types */
52 const unsigned char option_lengths[] = {
65 /* get an option with bounds checking (warning, not aligned). */
66 uint8_t *get_option(struct dhcpMessage *packet, int code)
70 int over = 0, done = 0, curr = OPTION_FIELD;
72 optionptr = packet->options;
77 bb_error_msg("bogus packet, option fields too long");
80 if (optionptr[i + OPT_CODE] == code) {
81 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
82 bb_error_msg("bogus packet, option fields too long");
85 return optionptr + i + 2;
87 switch (optionptr[i + OPT_CODE]) {
91 case DHCP_OPTION_OVER:
92 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
93 bb_error_msg("bogus packet, option fields too long");
96 over = optionptr[i + 3];
97 i += optionptr[OPT_LEN] + 2;
100 if (curr == OPTION_FIELD && over & FILE_FIELD) {
101 optionptr = packet->file;
105 } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
106 optionptr = packet->sname;
113 i += optionptr[OPT_LEN + i] + 2;
120 /* return the position of the 'end' option (no bounds checking) */
121 int end_option(uint8_t *optionptr)
125 while (optionptr[i] != DHCP_END) {
126 if (optionptr[i] == DHCP_PADDING) i++;
127 else i += optionptr[i + OPT_LEN] + 2;
133 /* add an option string to the options (an option string contains an option code,
134 * length, then data) */
135 int add_option_string(uint8_t *optionptr, uint8_t *string)
137 int end = end_option(optionptr);
139 /* end position + string length + option code/length + end option */
140 if (end + string[OPT_LEN] + 2 + 1 >= 308) {
141 bb_error_msg("option 0x%02x did not fit into the packet",
145 DEBUG("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;
152 /* add a one to four byte option to a packet */
153 int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
155 const struct dhcp_option *dh;
157 for (dh = dhcp_options; dh->code; dh++) {
158 if (dh->code == code) {
159 uint8_t option[6], len;
161 option[OPT_CODE] = code;
162 len = option_lengths[dh->flags & TYPE_MASK];
163 option[OPT_LEN] = len;
164 if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);
165 /* This memcpy is for broken processors which can't
166 * handle a simple unaligned 32-bit assignment */
167 memcpy(&option[OPT_DATA], &data, 4);
168 return add_option_string(optionptr, option);
172 bb_error_msg("cannot add option 0x%02x", code);