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-rw-r--r--networking/udhcp/options.c230
1 files changed, 230 insertions, 0 deletions
diff --git a/networking/udhcp/options.c b/networking/udhcp/options.c
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1/*
2 * options.c -- DHCP server option packet tools
3 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
4 */
5
6#include <stdio.h>
7#include <stdlib.h>
8#include <string.h>
9
10#include "debug.h"
11#include "dhcpd.h"
12#include "files.h"
13#include "options.h"
14#include "leases.h"
15
16
17/* supported options are easily added here */
18struct dhcp_option options[] = {
19 /* name[10] flags code */
20 {"subnet", OPTION_IP | OPTION_REQ, 0x01},
21 {"timezone", OPTION_S32, 0x02},
22 {"router", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x03},
23 {"timesvr", OPTION_IP | OPTION_LIST, 0x04},
24 {"namesvr", OPTION_IP | OPTION_LIST, 0x05},
25 {"dns", OPTION_IP | OPTION_LIST | OPTION_REQ, 0x06},
26 {"logsvr", OPTION_IP | OPTION_LIST, 0x07},
27 {"cookiesvr", OPTION_IP | OPTION_LIST, 0x08},
28 {"lprsvr", OPTION_IP | OPTION_LIST, 0x09},
29 {"hostname", OPTION_STRING | OPTION_REQ, 0x0c},
30 {"bootsize", OPTION_U16, 0x0d},
31 {"domain", OPTION_STRING | OPTION_REQ, 0x0f},
32 {"swapsvr", OPTION_IP, 0x10},
33 {"rootpath", OPTION_STRING, 0x11},
34 {"ipttl", OPTION_U8, 0x17},
35 {"mtu", OPTION_U16, 0x1a},
36 {"broadcast", OPTION_IP | OPTION_REQ, 0x1c},
37 {"ntpsrv", OPTION_IP | OPTION_LIST, 0x2a},
38 {"wins", OPTION_IP | OPTION_LIST, 0x2c},
39 {"requestip", OPTION_IP, 0x32},
40 {"lease", OPTION_U32, 0x33},
41 {"dhcptype", OPTION_U8, 0x35},
42 {"serverid", OPTION_IP, 0x36},
43 {"message", OPTION_STRING, 0x38},
44 {"tftp", OPTION_STRING, 0x42},
45 {"bootfile", OPTION_STRING, 0x43},
46 {"", 0x00, 0x00}
47};
48
49/* Lengths of the different option types */
50int option_lengths[] = {
51 [OPTION_IP] = 4,
52 [OPTION_IP_PAIR] = 8,
53 [OPTION_BOOLEAN] = 1,
54 [OPTION_STRING] = 1,
55 [OPTION_U8] = 1,
56 [OPTION_U16] = 2,
57 [OPTION_S16] = 2,
58 [OPTION_U32] = 4,
59 [OPTION_S32] = 4
60};
61
62
63/* get an option with bounds checking (warning, not aligned). */
64unsigned char *get_option(struct dhcpMessage *packet, int code)
65{
66 int i, length;
67 unsigned char *optionptr;
68 int over = 0, done = 0, curr = OPTION_FIELD;
69
70 optionptr = packet->options;
71 i = 0;
72 length = 308;
73 while (!done) {
74 if (i >= length) {
75 LOG(LOG_WARNING, "bogus packet, option fields too long.");
76 return NULL;
77 }
78 if (optionptr[i + OPT_CODE] == code) {
79 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
80 LOG(LOG_WARNING, "bogus packet, option fields too long.");
81 return NULL;
82 }
83 return optionptr + i + 2;
84 }
85 switch (optionptr[i + OPT_CODE]) {
86 case DHCP_PADDING:
87 i++;
88 break;
89 case DHCP_OPTION_OVER:
90 if (i + 1 + optionptr[i + OPT_LEN] >= length) {
91 LOG(LOG_WARNING, "bogus packet, option fields too long.");
92 return NULL;
93 }
94 over = optionptr[i + 3];
95 i += optionptr[OPT_LEN] + 2;
96 break;
97 case DHCP_END:
98 if (curr == OPTION_FIELD && over & FILE_FIELD) {
99 optionptr = packet->file;
100 i = 0;
101 length = 128;
102 curr = FILE_FIELD;
103 } else if (curr == FILE_FIELD && over & SNAME_FIELD) {
104 optionptr = packet->sname;
105 i = 0;
106 length = 64;
107 curr = SNAME_FIELD;
108 } else done = 1;
109 break;
110 default:
111 i += optionptr[OPT_LEN + i] + 2;
112 }
113 }
114 return NULL;
115}
116
117
118/* return the position of the 'end' option (no bounds checking) */
119int end_option(unsigned char *optionptr)
120{
121 int i = 0;
122
123 while (optionptr[i] != DHCP_END) {
124 if (optionptr[i] == DHCP_PADDING) i++;
125 else i += optionptr[i + OPT_LEN] + 2;
126 }
127 return i;
128}
129
130
131/* add an option string to the options (an option string contains an option code,
132 * length, then data) */
133int add_option_string(unsigned char *optionptr, unsigned char *string)
134{
135 int end = end_option(optionptr);
136
137 /* end position + string length + option code/length + end option */
138 if (end + string[OPT_LEN] + 2 + 1 >= 308) {
139 LOG(LOG_ERR, "Option 0x%02x did not fit into the packet!", string[OPT_CODE]);
140 return 0;
141 }
142 DEBUG(LOG_INFO, "adding option 0x%02x", string[OPT_CODE]);
143 memcpy(optionptr + end, string, string[OPT_LEN] + 2);
144 optionptr[end + string[OPT_LEN] + 2] = DHCP_END;
145 return string[OPT_LEN] + 2;
146}
147
148
149/* add a one to four byte option to a packet */
150int add_simple_option(unsigned char *optionptr, unsigned char code, u_int32_t data)
151{
152 char length = 0;
153 int i;
154 unsigned char option[2 + 4];
155 unsigned char *u8;
156 u_int16_t *u16;
157 u_int32_t *u32;
158 u_int32_t aligned;
159 u8 = (unsigned char *) &aligned;
160 u16 = (u_int16_t *) &aligned;
161 u32 = &aligned;
162
163 for (i = 0; options[i].code; i++)
164 if (options[i].code == code) {
165 length = option_lengths[options[i].flags & TYPE_MASK];
166 }
167
168 if (!length) {
169 DEBUG(LOG_ERR, "Could not add option 0x%02x", code);
170 return 0;
171 }
172
173 option[OPT_CODE] = code;
174 option[OPT_LEN] = length;
175
176 switch (length) {
177 case 1: *u8 = data; break;
178 case 2: *u16 = data; break;
179 case 4: *u32 = data; break;
180 }
181 memcpy(option + 2, &aligned, length);
182 return add_option_string(optionptr, option);
183}
184
185
186/* find option 'code' in opt_list */
187struct option_set *find_option(struct option_set *opt_list, char code)
188{
189 while (opt_list && opt_list->data[OPT_CODE] < code)
190 opt_list = opt_list->next;
191
192 if (opt_list && opt_list->data[OPT_CODE] == code) return opt_list;
193 else return NULL;
194}
195
196
197/* add an option to the opt_list */
198void attach_option(struct option_set **opt_list, struct dhcp_option *option, char *buffer, int length)
199{
200 struct option_set *existing, *new, **curr;
201
202 /* add it to an existing option */
203 if ((existing = find_option(*opt_list, option->code))) {
204 DEBUG(LOG_INFO, "Attaching option %s to existing member of list", option->name);
205 if (option->flags & OPTION_LIST) {
206 if (existing->data[OPT_LEN] + length <= 255) {
207 existing->data = realloc(existing->data,
208 existing->data[OPT_LEN] + length + 2);
209 memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
210 existing->data[OPT_LEN] += length;
211 } /* else, ignore the data, we could put this in a second option in the future */
212 } /* else, ignore the new data */
213 } else {
214 DEBUG(LOG_INFO, "Attaching option %s to list", option->name);
215
216 /* make a new option */
217 new = malloc(sizeof(struct option_set));
218 new->data = malloc(length + 2);
219 new->data[OPT_CODE] = option->code;
220 new->data[OPT_LEN] = length;
221 memcpy(new->data + 2, buffer, length);
222
223 curr = opt_list;
224 while (*curr && (*curr)->data[OPT_CODE] < option->code)
225 curr = &(*curr)->next;
226
227 new->next = *curr;
228 *curr = new;
229 }
230}
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