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 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},
49 /* Lengths of the different option types */
50 int option_lengths[] = {
63 /* get an option with bounds checking (warning, not aligned). */
64 uint8_t *get_option(struct dhcpMessage *packet, int code)
68 int over = 0, done = 0, curr = OPTION_FIELD;
70 optionptr = packet->options;
75 bb_error_msg("bogus packet, option fields too long");
78 if (optionptr[i + OPT_CODE] == code) {
79 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
80 bb_error_msg("bogus packet, option fields too long");
83 return optionptr + i + 2;
85 switch (optionptr[i + OPT_CODE]) {
89 case DHCP_OPTION_OVER:
90 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
91 bb_error_msg("bogus packet, option fields too long");
94 over = optionptr[i + 3];
95 i += optionptr[OPT_LEN] + 2;
98 if (curr == OPTION_FIELD && over & FILE_FIELD) {
99 optionptr = packet->file;
103 } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
104 optionptr = packet->sname;
111 i += optionptr[OPT_LEN + i] + 2;
118 /* return the position of the 'end' option (no bounds checking) */
119 int end_option(uint8_t *optionptr)
123 while (optionptr[i] != DHCP_END) {
124 if (optionptr[i] == DHCP_PADDING) i++;
125 else i += optionptr[i + OPT_LEN] + 2;
131 /* add an option string to the options (an option string contains an option code,
132 * length, then data) */
133 int add_option_string(uint8_t *optionptr, uint8_t *string)
135 int end = end_option(optionptr);
137 /* end position + string length + option code/length + end option */
138 if (end + string[OPT_LEN] + 2 + 1 >= 308) {
139 bb_error_msg("option 0x%02x did not fit into the packet",
143 DEBUG("adding option 0x%02x", string[OPT_CODE]);
144 memcpy(optionptr + end, string, string[OPT_LEN] + 2);
145 optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
146 return string[OPT_LEN] + 2;
150 /* add a one to four byte option to a packet */
151 int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
153 struct dhcp_option *dh;
155 for (dh=dhcp_options; dh->code; dh++) {
156 if (dh->code == code) {
157 uint8_t option[6], len;
159 option[OPT_CODE] = code;
160 len = option_lengths[dh->flags & TYPE_MASK];
161 option[OPT_LEN] = len;
162 if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);
163 /* This memcpy is for broken processors which can't
164 * handle a simple unaligned 32-bit assignment */
165 memcpy(&option[OPT_DATA], &data, 4);
166 return add_option_string(optionptr, option);
170 bb_error_msg("cannot add option 0x%02x", code);