58 lines
1.4 KiB
C
Executable file
58 lines
1.4 KiB
C
Executable file
/* dhcp_init(), dhcp_settag() Author: Kees J. Bot
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* 1 Dec 2000
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*/
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#define nil ((void*)0)
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#include <stddef.h>
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#include <string.h>
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#include <sys/types.h>
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#include <net/hton.h>
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#include <net/gen/in.h>
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#include <net/gen/dhcp.h>
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#define arraysize(a) (sizeof(a) / sizeof((a)[0]))
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#define arraylimit(a) ((a) + arraysize(a))
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void dhcp_init(dhcp_t *dp)
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{
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/* Initialize a DHCP packet. */
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memset(dp, 0, offsetof(dhcp_t, magic));
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dp->magic= DHCP_MAGIC;
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memset(dp->options, 255, sizeof(dp->options));
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}
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int dhcp_settag(dhcp_t *dp, int tag, void *data, size_t len)
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{
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/* Add a tag to a DHCP packet. No padding. Only do the options field.
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* (This is Minix, we don't need megabytes of silly bits of data.)
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* The length may be zero to delete a tag.
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*/
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u8_t *p;
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int n;
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if (tag <= 0 || tag >= 255) return 0;
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for (p= dp->options; p < arraylimit(dp->options) && *p != 255; p += n) {
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n= 1 + 1 + p[1];
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if (*p == tag) {
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/* The tag is already there, remove it so it gets replaced. */
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memmove(p, p + n, arraylimit(dp->options) - (p + n));
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memset(arraylimit(dp->options) - n, 255, n);
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n= 0;
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}
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}
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/* Add tag. */
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if (len == 0) {
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/* We're merely deleting a tag. */
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} else
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if (p + 1 + 1 + len <= arraylimit(dp->options)) {
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*p++ = tag;
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*p++ = len;
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memcpy(p, data, len);
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} else {
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/* Oops, it didn't fit? Is this really Minix??? */
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return 0;
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}
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return 1;
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}
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