1 | /* vi: set sw=4 ts=4: */
|
---|
2 | /*
|
---|
3 | * options.c -- DHCP server option packet tools
|
---|
4 | * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
|
---|
5 | */
|
---|
6 |
|
---|
7 | #include "common.h"
|
---|
8 | #include "dhcpd.h"
|
---|
9 | #include "options.h"
|
---|
10 |
|
---|
11 |
|
---|
12 | /* supported options are easily added here */
|
---|
13 | const struct dhcp_option dhcp_options[] = {
|
---|
14 | /* name[12] 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_LIST | 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 | #if ENABLE_FEATURE_RFC3397
|
---|
47 | {"search", OPTION_STR1035 | OPTION_LIST | OPTION_REQ, 0x77},
|
---|
48 | #endif
|
---|
49 | /* MSIE's "Web Proxy Autodiscovery Protocol" support */
|
---|
50 | {"wpad", OPTION_STRING, 0xfc},
|
---|
51 | {"", 0x00, 0x00}
|
---|
52 | };
|
---|
53 |
|
---|
54 | /* Lengths of the different option types */
|
---|
55 | const unsigned char option_lengths[] ALIGN1 = {
|
---|
56 | [OPTION_IP] = 4,
|
---|
57 | [OPTION_IP_PAIR] = 8,
|
---|
58 | [OPTION_BOOLEAN] = 1,
|
---|
59 | [OPTION_STRING] = 1,
|
---|
60 | #if ENABLE_FEATURE_RFC3397
|
---|
61 | [OPTION_STR1035] = 1,
|
---|
62 | #endif
|
---|
63 | [OPTION_U8] = 1,
|
---|
64 | [OPTION_U16] = 2,
|
---|
65 | [OPTION_S16] = 2,
|
---|
66 | [OPTION_U32] = 4,
|
---|
67 | [OPTION_S32] = 4
|
---|
68 | };
|
---|
69 |
|
---|
70 |
|
---|
71 | /* get an option with bounds checking (warning, not aligned). */
|
---|
72 | uint8_t *get_option(struct dhcpMessage *packet, int code)
|
---|
73 | {
|
---|
74 | int i, length;
|
---|
75 | uint8_t *optionptr;
|
---|
76 | int over = 0, done = 0, curr = OPTION_FIELD;
|
---|
77 |
|
---|
78 | optionptr = packet->options;
|
---|
79 | i = 0;
|
---|
80 | length = 308;
|
---|
81 | while (!done) {
|
---|
82 | if (i >= length) {
|
---|
83 | bb_error_msg("bogus packet, option fields too long");
|
---|
84 | return NULL;
|
---|
85 | }
|
---|
86 | if (optionptr[i + OPT_CODE] == code) {
|
---|
87 | if (i + 1 + optionptr[i + OPT_LEN] >= length) {
|
---|
88 | bb_error_msg("bogus packet, option fields too long");
|
---|
89 | return NULL;
|
---|
90 | }
|
---|
91 | return optionptr + i + 2;
|
---|
92 | }
|
---|
93 | switch (optionptr[i + OPT_CODE]) {
|
---|
94 | case DHCP_PADDING:
|
---|
95 | i++;
|
---|
96 | break;
|
---|
97 | case DHCP_OPTION_OVER:
|
---|
98 | if (i + 1 + optionptr[i + OPT_LEN] >= length) {
|
---|
99 | bb_error_msg("bogus packet, option fields too long");
|
---|
100 | return NULL;
|
---|
101 | }
|
---|
102 | over = optionptr[i + 3];
|
---|
103 | i += optionptr[OPT_LEN] + 2;
|
---|
104 | break;
|
---|
105 | case DHCP_END:
|
---|
106 | if (curr == OPTION_FIELD && over & FILE_FIELD) {
|
---|
107 | optionptr = packet->file;
|
---|
108 | i = 0;
|
---|
109 | length = 128;
|
---|
110 | curr = FILE_FIELD;
|
---|
111 | } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
|
---|
112 | optionptr = packet->sname;
|
---|
113 | i = 0;
|
---|
114 | length = 64;
|
---|
115 | curr = SNAME_FIELD;
|
---|
116 | } else done = 1;
|
---|
117 | break;
|
---|
118 | default:
|
---|
119 | i += optionptr[OPT_LEN + i] + 2;
|
---|
120 | }
|
---|
121 | }
|
---|
122 | return NULL;
|
---|
123 | }
|
---|
124 |
|
---|
125 |
|
---|
126 | /* return the position of the 'end' option (no bounds checking) */
|
---|
127 | int end_option(uint8_t *optionptr)
|
---|
128 | {
|
---|
129 | int i = 0;
|
---|
130 |
|
---|
131 | while (optionptr[i] != DHCP_END) {
|
---|
132 | if (optionptr[i] == DHCP_PADDING) i++;
|
---|
133 | else i += optionptr[i + OPT_LEN] + 2;
|
---|
134 | }
|
---|
135 | return i;
|
---|
136 | }
|
---|
137 |
|
---|
138 |
|
---|
139 | /* add an option string to the options (an option string contains an option code,
|
---|
140 | * length, then data) */
|
---|
141 | int add_option_string(uint8_t *optionptr, uint8_t *string)
|
---|
142 | {
|
---|
143 | int end = end_option(optionptr);
|
---|
144 |
|
---|
145 | /* end position + string length + option code/length + end option */
|
---|
146 | if (end + string[OPT_LEN] + 2 + 1 >= 308) {
|
---|
147 | bb_error_msg("option 0x%02x did not fit into the packet",
|
---|
148 | string[OPT_CODE]);
|
---|
149 | return 0;
|
---|
150 | }
|
---|
151 | DEBUG("adding option 0x%02x", string[OPT_CODE]);
|
---|
152 | memcpy(optionptr + end, string, string[OPT_LEN] + 2);
|
---|
153 | optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
|
---|
154 | return string[OPT_LEN] + 2;
|
---|
155 | }
|
---|
156 |
|
---|
157 |
|
---|
158 | /* add a one to four byte option to a packet */
|
---|
159 | int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data)
|
---|
160 | {
|
---|
161 | const struct dhcp_option *dh;
|
---|
162 |
|
---|
163 | for (dh = dhcp_options; dh->code; dh++) {
|
---|
164 | if (dh->code == code) {
|
---|
165 | uint8_t option[6], len;
|
---|
166 |
|
---|
167 | option[OPT_CODE] = code;
|
---|
168 | len = option_lengths[dh->flags & TYPE_MASK];
|
---|
169 | option[OPT_LEN] = len;
|
---|
170 | if (BB_BIG_ENDIAN) data <<= 8 * (4 - len);
|
---|
171 | /* This memcpy is for broken processors which can't
|
---|
172 | * handle a simple unaligned 32-bit assignment */
|
---|
173 | memcpy(&option[OPT_DATA], &data, 4);
|
---|
174 | return add_option_string(optionptr, option);
|
---|
175 | }
|
---|
176 | }
|
---|
177 |
|
---|
178 | bb_error_msg("cannot add option 0x%02x", code);
|
---|
179 | return 0;
|
---|
180 | }
|
---|