13 Apr
2012
13 Apr
'12
5:01 p.m.
Hello,
I haven't looked at the issue reported by Hugh, so by now just comments
on srutils/sruid.
The idea was to have an unique id generator without linking to an
external library -- my first purpose was to use it for temporary GRUU
ids (RFC5627), I am just about to push to master the gruu support in
registrar/usrloc.
Then I thought it might be useful in other places, such as dialog unique id.
I added it as part of lib, since its target usage was for modules so
far, but if needed for some core processing, the two files (rather small
by now) can be moved in the core.
Cheers,
Daniel
On 4/13/12 2:50 PM, Henning Westerholt wrote:
On Friday 13 April 2012, Hugh Waite wrote:
--
Daniel-Constantin Mierla
Kamailio Advanced Training, April 23-26, 2012, Berlin, Germany
http://www.asipto.com/index.php/kamailio-advanced-training/
I have a question about random number generation
within kamailio.
A number of modules use rand() to get a random value and in some places
is re-seeding with srand(). I believe this is dangerous because rand()
is used in the Via branch tag generator.
We have detected some real bugs (where srand is reseeding with 0 for
every message, causing transaction mis-matching) but I'm not sure of the
correct way to fix this (other than remove srand()).
Should all modules be using a 'core' random function (e.g. in srutils?)
? And if so, is this library documented?
Regards,
Hugh
Hi Hugh,
for the purpose getting a pseudo-random number (i.e. not for cryptographic
functionality) we should consolidate on a single random function. There is the
recent introduced srutils/sruid code, then there exists a (IMHO stronger)
pseudo-random number generator in rand/fastrand and then there is of course
rand().
Maybe Daniel can comment about the purpose of the srutils function, IMHO
consolidating on fastrand or one of the stronger function (d_rand etc..) from
stdlib.h would be fine.
The re-seeding the internal state of rand() with srand during runtime sounds
wrong toe me and should be removed/ fixed.
Viele Grüße/ best regards,
Henning Westerholt
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