[ldns-users] drill and truncated packets

Jelte Jansen jelte at NLnetLabs.nl
Wed Aug 20 13:19:59 UTC 2008


on another list we've received a sort-of complaint that drill does not
automatically fall back to TCP when it receives a truncated packet (in
normal usage), while dig does.

For normal resolvers, and in 'resolving mode' drill/ldns does fall back
to tcp, but in 'single-query' mode it only prints the packet that is
returned; ie. an empty answer with the tc flag set in this case.

While this has been my own design choice (print what is returned, don't
do magic) i understand the confusion this might bring, and there are a
few options to handle this:

1. leave it as it is (just print the packet and hope people will look at
the flags section as soon as they see something they didn't expect)
2. implement tcp fallback by default (and silently drop the truncated
packet if verbosity level is not changed)
3. add a warning that the packet received was truncated, with a hint to
use tcp or a larger buffer size

For the moment i chose option 3 (subversion trunk rev. 2701). If people
have a strong opinion to do either 1 or 2, please let me know.


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