Line | |
---|
1 | /* dhcp_gettag() Author: Kees J. Bot
|
---|
2 | * 1 Dec 2000
|
---|
3 | */
|
---|
4 | #define nil ((void*)0)
|
---|
5 | #include <stddef.h>
|
---|
6 | #include <string.h>
|
---|
7 | #include <sys/types.h>
|
---|
8 | #include <net/hton.h>
|
---|
9 | #include <net/gen/in.h>
|
---|
10 | #include <net/gen/dhcp.h>
|
---|
11 |
|
---|
12 | #define arraysize(a) (sizeof(a) / sizeof((a)[0]))
|
---|
13 |
|
---|
14 | int dhcp_gettag(dhcp_t *dp, int searchtag, u8_t **pdata, size_t *plen)
|
---|
15 | {
|
---|
16 | /* Find a tag in the options field, or possibly in the file or sname
|
---|
17 | * fields. Return true iff found, and return the data and/or length if
|
---|
18 | * their pointers are non-null.
|
---|
19 | */
|
---|
20 | u8_t *p;
|
---|
21 | u8_t *optfield[3];
|
---|
22 | size_t optlen[3];
|
---|
23 | int i, tag, len;
|
---|
24 |
|
---|
25 | /* The DHCP magic number must be correct, or no tags. */
|
---|
26 | if (dp->magic != DHCP_MAGIC) return 0;
|
---|
27 |
|
---|
28 | optfield[0]= dp->options;
|
---|
29 | optlen[0]= arraysize(dp->options);
|
---|
30 | optfield[1]= dp->file;
|
---|
31 | optlen[1]= 0; /* Unknown if used for options yet. */
|
---|
32 | optfield[2]= dp->sname;
|
---|
33 | optlen[2]= 0;
|
---|
34 |
|
---|
35 | for (i= 0; i < 3; i++) {
|
---|
36 | p= optfield[i];
|
---|
37 | while (p < optfield[i] + optlen[i]) {
|
---|
38 | tag= *p++;
|
---|
39 | if (tag == 255) break;
|
---|
40 | len= tag == 0 ? 0 : *p++;
|
---|
41 | if (tag == searchtag) {
|
---|
42 | if (pdata != nil) *pdata= p;
|
---|
43 | if (plen != nil) *plen= len;
|
---|
44 | return 1;
|
---|
45 | }
|
---|
46 | if (tag == DHCP_TAG_OVERLOAD) {
|
---|
47 | /* There are also options in the file or sname field. */
|
---|
48 | if (*p & 1) optlen[1]= arraysize(dp->file);
|
---|
49 | if (*p & 2) optlen[1]= arraysize(dp->sname);
|
---|
50 | }
|
---|
51 | p += len;
|
---|
52 | }
|
---|
53 | }
|
---|
54 | return 0;
|
---|
55 | }
|
---|
Note:
See
TracBrowser
for help on using the repository browser.