Check that table evenly divides 256 when generating random string.

Check that table evenly divides 256 when generating random string.

This prevents biased modulo arithmetic when selecting a character for a
random value from the provided table.

BUG=webrtc:5870
Committed: https://crrev.com/e3eff7c0625f82bf2e6dde1539699296a5415ae0
Cr-Commit-Position: refs/heads/master@{#13683}

[joachim, 2016-07-01 22:27:33]

jbauch@webrtc.org changed reviewers:
+ mattdr@webrtc.org

[joachim, 2016-07-01 22:27:34]

Ptal

https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.cc
File webrtc/base/helpers.cc (right):

https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.cc#newcod...
webrtc/base/helpers.cc:222: static bool CreateRandomString(size_t len,
Function is not exposed through header, so I chaned it to static.

[mattdr-at-webrtc.org, 2016-07-01 22:34:22]

LGTM. Thanks!

https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h
File webrtc/base/helpers.h (right):

https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h#newcode38
webrtc/base/helpers.h:38: // number generator failed or the table doesn't evenly
divide 256.
number generator failed. For ease of implementation, the function requires that
the table size evenly divide 256; otherwise, it returns false.

[joachim, 2016-07-01 22:37:10]

jbauch@webrtc.org changed reviewers:
+ pthatcher@webrtc.org

[joachim, 2016-07-01 22:37:11]

+pthatcher for owner review

https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h
File webrtc/base/helpers.h (right):

https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h#newcode38
webrtc/base/helpers.h:38: // number generator failed or the table doesn't evenly
divide 256.
On 2016/07/01 22:34:22, mattdr1 wrote:
> number generator failed. For ease of implementation, the function requires
that
> the table size evenly divide 256; otherwise, it returns false.

Done.

[joachim, 2016-07-18 10:38:15]

On 2016/07/01 22:37:11, joachim wrote:
> +pthatcher for owner review

Ping?

> https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h
> File webrtc/base/helpers.h (right):
> 
>
https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h#newcode38
> webrtc/base/helpers.h:38: // number generator failed or the table doesn't
evenly
> divide 256.
> On 2016/07/01 22:34:22, mattdr1 wrote:
> > number generator failed. For ease of implementation, the function requires
> that
> > the table size evenly divide 256; otherwise, it returns false.
> 
> Done.

[joachim, 2016-07-28 11:56:22]

On 2016/07/18 10:38:15, joachim wrote:
> On 2016/07/01 22:37:11, joachim wrote:
> > +pthatcher for owner review
> 
> Ping?
> 
> > https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h
> > File webrtc/base/helpers.h (right):
> > 
> >
>
https://codereview.webrtc.org/2115793003/diff/1/webrtc/base/helpers.h#newcode38
> > webrtc/base/helpers.h:38: // number generator failed or the table doesn't
> evenly
> > divide 256.
> > On 2016/07/01 22:34:22, mattdr1 wrote:
> > > number generator failed. For ease of implementation, the function requires
> > that
> > > the table size evenly divide 256; otherwise, it returns false.
> > 
> > Done.

pthatcher, friendly ping

[pthatcher1, 2016-08-08 22:19:20]

lgtm

[joachim, 2016-08-08 22:31:27]

The CQ bit was checked by jbauch@webrtc.org

[joachim, 2016-08-08 22:31:28]

The patchset sent to the CQ was uploaded after l-g-t-m from mattdr@webrtc.org
Link to the patchset: https://codereview.webrtc.org/2115793003/#ps20001 (title:
"Updated comment.")

[commit-bot: I haz the power, 2016-08-08 22:31:34]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2016-08-08 22:37:34]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2016-08-08 22:37:35]

Try jobs failed on following builders:
  mac_baremetal on master.tryserver.webrtc (JOB_FAILED,
http://build.chromium.org/p/tryserver.webrtc/builders/mac_baremetal/builds/13193)

[joachim, 2016-08-08 23:32:38]

The CQ bit was checked by jbauch@webrtc.org

[joachim, 2016-08-08 23:32:39]

The patchset sent to the CQ was uploaded after l-g-t-m from mattdr@webrtc.org,
pthatcher@webrtc.org
Link to the patchset: https://codereview.webrtc.org/2115793003/#ps40001 (title:
"Rebased")

[commit-bot: I haz the power, 2016-08-08 23:32:42]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.webrtc.org/...

[commit-bot: I haz the power, 2016-08-09 00:13:37]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2016-08-09 00:13:51]

Description was changed from

==========
Check that table evenly divides 256 when generating random string.

This prevents biased modulo arithmetic when selecting a character for a
random value from the provided table.

BUG=webrtc:5870
==========

to

==========
Check that table evenly divides 256 when generating random string.

This prevents biased modulo arithmetic when selecting a character for a
random value from the provided table.

BUG=webrtc:5870

Committed: https://crrev.com/e3eff7c0625f82bf2e6dde1539699296a5415ae0
Cr-Commit-Position: refs/heads/master@{#13683}
==========

[commit-bot: I haz the power, 2016-08-09 00:13:52]

Patchset 3 (id:??) landed as
https://crrev.com/e3eff7c0625f82bf2e6dde1539699296a5415ae0
Cr-Commit-Position: refs/heads/master@{#13683}