On Sunday 17 October 2010 10:25, Vladislav Grishenko wrote:
> Hello,
> Sorry, previous message doesn't include description.
>
> Commit
> http://git.busybox.net/busybox/commit/?id=7d3a48a003cd645edfae2b404493688022
> b13193
> revealed incorrect OPTION_IP_PAIR implementation, which doesn't respect
> option length and causes
> erroneous classful routes, composed from garbage or first bytes from the
> next DHCP packet option.
> Patch is attached.
Good catch!
I propose the fix which is less mind-bending: remove all +/-4 tricks
in OPTION_IP_PAIR (they are hard to follow and that's why they contained
a sublte bug), and add ip_ofs variable which may be used to advance
"option" pointer in OPTION_IP:
while (len >= optlen) {
+ unsigned ip_ofs = 0;
switch (type) {
case OPTION_IP_PAIR:
dest += sprint_nip(dest, "", option);
*dest++ = '/';
- option += 4;
- optlen = 4;
+ ip_ofs = 4;
/* fall through */
case OPTION_IP:
- dest += sprint_nip(dest, "", option);
+ dest += sprint_nip(dest, "", option + ip_ofs);
break;
--
vda
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