tree 990bc2d1894f2b136c91f902aef41313b7d2831f
parent bf9498a31beb41078ebf257c54b7acb879bcb98b
author Willy Tarreau <w@1wt.eu> 1634191908 +0200
committer Willy Tarreau <w@1wt.eu> 1634239458 +0200
encoding latin1

BUG/MEDIUM: resolver: make sure to always use the correct hostname length

In issue #1411, @jjiang-stripe reports that do-resolve() sometimes seems
to be trying to resolve crap from random memory contents.

The issue is that action_prepare_for_resolution() tries to measure the
input string by itself using strlen(), while resolv_action_do_resolve()
directly passes it a pointer to the sample, omitting the known length.
Thus of course any other header present after the host in memory are
appended to the host value. It could theoretically crash if really
unlucky, with a buffer that does not contain any zero including in the
index at the end, and if the HTX buffer ends on an allocation boundary.
In practice it should be too low a probability to have ever been observed.

This patch modifies the action_prepare_for_resolution() function to take
the string length on with the host name on input and pass that down the
chain. This should be backported to 2.0 along with commit "MINOR:
resolvers: fix the resolv_str_to_dn_label() API about trailing zero".