[Bug 3979] udhcpc should filter out malicious hostnames passed in option 0x0c

bugzilla at busybox.net bugzilla at busybox.net
Sun Apr 20 10:31:30 UTC 2014


--- Comment #17 from danny at mellanox.com 2014-04-20 10:31:29 UTC ---

> Option 119 is not a string option, it uses "\003foo\004blah\003com\000"
> encoding (RFC 1035).
> > So, following advices to use "right options", we hitting even more problems and incompatibilities in different OS.

Everywhere in man's it written as "string"...

> Because many clients have bugs in handling more recently introduced options.
> Such is life. Bugs needs to be filed in bugzillas to get them fixed.

Here you too optimistic. Nobody bother to fix old stuff, especially on old

> > Can't provide you with tcpdump yet, but you already know what is there.
> I do want tcpdump, because I in fact don't know what _exactly_ is there. For
> example, trailing dot problem can exist in bbox's DHCP client, udhcpc, and in
> order to test it, I want to see a real-world example of the packed, instead of
> assuming what's there.

Sent you by email.

Anyway, there is a way, which can be acceptable by all parties:

if (ch == '\0' || ch == ' ' || ch == '.' )
                               return label;

Here you will get domain name in any case + ' ' is not evil + RFC conformant +
nothing broken.

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