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Some clients don't parse a DHO_DHCP_OPTION_OVERLOAD option the way

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I expected. They object if there are no bits set in the option
value. So just use DHO_PAD in the reserved space unless at least
one of the bits is set.

Various versions tested by Tobias Ulmer on OpenSolaris, matthieu@
on busybox's DHCP client, and Uwe Dippel on Solaris. All of which
failed before.
This commit is contained in:
krw 2008-11-08 01:42:24 +00:00
parent 1ca17e461a
commit 920fcdb10c
1 changed files with 14 additions and 12 deletions
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26
usr.sbin/dhcpd/options.c
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@ -1,4 +1,4 @@
/* $OpenBSD: options.c,v 1.22 2008/09/10 00:22:49 reyk Exp $ */
/* $OpenBSD: options.c,v 1.23 2008/11/08 01:42:24 krw Exp $ */
/* DHCP options parsing and reassembly. */
@ -381,19 +381,19 @@ store_options(unsigned char *buffer, int main_buffer_size,
int second_cutoff;
int bufix = 0;
overload &= 3; /* Only consider valid bits. */
cutoff = main_buffer_size;
second_cutoff = cutoff + ((overload & 1) ? DHCP_FILE_LEN : 0);
buflen = second_cutoff + ((overload & 2) ? DHCP_SNAME_LEN : 0);
memset(buffer, DHO_PAD, buflen);
memcpy(buffer, DHCP_OPTIONS_COOKIE, 4);
bufix = 4;
if (overload) {
buffer[bufix++] = DHO_DHCP_OPTION_OVERLOAD;
buffer[bufix++] = 1;
buffer[bufix++] = 0; /* Note: value is at index [6] */
}
if (overload)
bufix = 7; /* Reserve space for DHO_DHCP_OPTION_OVERLOAD. */
else
bufix = 4;
/*
* Store options in the order they appear in the priority list.
@ -460,13 +460,15 @@ zapfrags:
buffer[bufix++] = DHO_END;
/* Fill in overload option value based on space used for options. */
if (overload && bufix > main_buffer_size) {
overflow = bufix - main_buffer_size;
overflow = bufix - main_buffer_size;
if (overload && overflow > 0) {
buffer[4] = DHO_DHCP_OPTION_OVERLOAD;
buffer[5] = 1;
if (overload & 1) {
buffer[6] = 1;
buffer[6] |= 1;
overflow -= DHCP_FILE_LEN;
}
if (overflow > 0)
if ((overload & 2) && overflow > 0)
buffer[6] |= 2;
}