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
16 /* supported options are easily added here */
17 struct dhcp_option dhcp_options[] = {
18 /* name[10] flags code */
19 {"subnet", OPTION_IP | OPTION_REQ, 0x01},
20 {"timezone", OPTION_S32, 0x02},
21 {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03},
22 {"timesvr", OPTION_IP | OPTION_LIST, 0x04},
23 {"namesvr", OPTION_IP | OPTION_LIST, 0x05},
24 {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06},
25 {"logsvr", OPTION_IP | OPTION_LIST, 0x07},
26 {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08},
27 {"lprsvr", OPTION_IP | OPTION_LIST, 0x09},
28 {"hostname", OPTION_STRING | OPTION_REQ, 0x0c},
29 {"bootsize", OPTION_U16, 0x0d},
30 {"domain", OPTION_STRING | OPTION_REQ, 0x0f},
31 {"swapsvr", OPTION_IP, 0x10},
32 {"rootpath", OPTION_STRING, 0x11},
33 {"ipttl", OPTION_U8, 0x17},
34 {"mtu", OPTION_U16, 0x1a},
35 {"broadcast", OPTION_IP | OPTION_REQ, 0x1c},
36 {"nisdomain", OPTION_STRING | OPTION_REQ, 0x28},
37 {"nissrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x29},
38 {"ntpsrv", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x2a},
39 {"wins", OPTION_IP | OPTION_LIST, 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 {"vendorclass", OPTION_STRING, 0x3C},
46 {"clientid", OPTION_STRING, 0x3D},
47 {"tftp", OPTION_STRING, 0x42},
48 {"bootfile", OPTION_STRING, 0x43},
49 {"userclass", OPTION_STRING, 0x4D},
53 /* Lengths of the different option types */
54 int option_lengths[] = {
67 /* get an option with bounds checking (warning, not aligned). */
68 uint8_t *get_option(struct dhcpMessage *packet, int code)
72 int over = 0, done = 0, curr = OPTION_FIELD;
74 optionptr = packet->options;
79 bb_error_msg("bogus packet, option fields too long");
82 if (optionptr[i + OPT_CODE] == code) {
83 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
84 bb_error_msg("bogus packet, option fields too long");
87 return optionptr + i + 2;
89 switch (optionptr[i + OPT_CODE]) {
93 case DHCP_OPTION_OVER:
94 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
95 bb_error_msg("bogus packet, option fields too long");
98 over = optionptr[i + 3];
99 i += optionptr[OPT_LEN] + 2;
102 if (curr == OPTION_FIELD && over & FILE_FIELD) {
103 optionptr = packet->file;
107 } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
108 optionptr = packet->sname;
115 i += optionptr[OPT_LEN + i] + 2;
122 /* return the position of the 'end' option (no bounds checking) */
123 int end_option(uint8_t *optionptr)
127 while (optionptr[i] != DHCP_END) {
128 if (optionptr[i] == DHCP_PADDING) i++;
129 else i += optionptr[i + OPT_LEN] + 2;
135 /* add an option string to the options (an option string contains an option code,
136 * length, then data) */
137 int add_option_string(uint8_t *optionptr, uint8_t *string)
139 int end = end_option(optionptr);
141 /* end position + string length + option code/length + end option */
142 if (end + string[OPT_LEN] + 2 + 1 >= 308) {
143 bb_error_msg("option 0x%02x did not fit into the packet",
147 DEBUG("adding option 0x%02x", string[OPT_CODE]);
148 memcpy(optionptr + end, string, string[OPT_LEN] + 2);
149 optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
150 return string[OPT_LEN] + 2;
154 /* add a one to four byte option to a packet */
155 int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
157 struct dhcp_option *dh;
159 for (dh=dhcp_options; dh->code; dh++) {
160 if (dh->code == code) {
161 uint8_t option[6], len;
163 option[OPT_CODE] = code;
164 len = option_lengths[dh->flags & TYPE_MASK];
165 option[OPT_LEN] = len;
166 if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);
167 /* This memcpy is for broken processors which can't
168 * handle a simple unaligned 32-bit assignment */
169 memcpy(&option[OPT_DATA], &data, 4);
170 return add_option_string(optionptr, option);
174 bb_error_msg("cannot add option 0x%02x", code);