When two or more absolute, two-label names are added to a completely
empty RBT, an extra, empty node for the root name will be created due to
node splitting. check_tree() expects that, but the extra node will not
be created when just one name is added to a completely empty RBT. This
problem could be handled inside check_tree(), but that would introduce
unnecessary complexity into it since adding a single name will result in
a different node count for a completely empty RBT (node count will be 1)
and an RBT containing only an empty node for the root name, created due
to prior node splitting (node count will be 2). Thus, first explicitly
create a node for the root name to prevent rare check_tree() failures
caused by a single name being added in the first iteration of the
insert/remove loop.
This commit reverts the previous change to use system provided
entropy, as (SYS_)getrandom is very slow on Linux because it is
a syscall.
The change introduced in this commit adds a new call isc_nonce_buf
that uses CSPRNG from cryptographic library provider to generate
secure data that can be and must be used for generating nonces.
Example usage would be DNS cookies.
The isc_random() API has been changed to use fast PRNG that is not
cryptographically secure, but runs entirely in user space. Two
contestants have been considered xoroshiro family of the functions
by Villa&Blackman and PCG by O'Neill. After a consideration the
xoshiro128starstar function has been used as uint32_t random number
provider because it is very fast and has good enough properties
for our usage pattern.
The other change introduced in the commit is the more extensive usage
of isc_random_uniform in places where the usage pattern was
isc_random() % n to prevent modulo bias. For usage patterns where
only 16 or 8 bits are needed (DNS Message ID), the isc_random()
functions has been renamed to isc_random32(), and isc_random16() and
isc_random8() functions have been introduced by &-ing the
isc_random32() output with 0xffff and 0xff. Please note that the
functions that uses stripped down bit count doesn't pass our
NIST SP 800-22 based random test.
The three functions has been modeled after the arc4random family of
functions, and they will always return random bytes.
The isc_random family of functions internally use these CSPRNG (if available):
1. getrandom() libc call (might be available on Linux and Solaris)
2. SYS_getrandom syscall (might be available on Linux, detected at runtime)
3. arc4random(), arc4random_buf() and arc4random_uniform() (available on BSDs and Mac OS X)
4. crypto library function:
4a. RAND_bytes in case OpenSSL
4b. pkcs_C_GenerateRandom() in case PKCS#11 library
Replace dns_fixedname_init() calls followed by dns_fixedname_name()
calls with calls to dns_fixedname_initname() where it is possible
without affecting current behavior and/or performance.
This patch was mostly prepared using Coccinelle and the following
semantic patch:
@@
expression fixedname, name;
@@
- dns_fixedname_init(&fixedname);
...
- name = dns_fixedname_name(&fixedname);
+ name = dns_fixedname_initname(&fixedname);
The resulting set of changes was then manually reviewed to exclude false
positives and apply minor tweaks.
It is likely that more occurrences of this pattern can be refactored in
an identical way. This commit only takes care of the low-hanging fruit.
No CHANGES entry was added as this commit mainly adds tests related
code.
Squashed commit of the following:
commit d3d44508daa128fb8b60f64b3a8c81f80602273d
Author: Evan Hunt <each@isc.org>
Date: Wed May 7 09:36:41 2014 -0700
[rt35904] remove private non-static names from .def file
commit dbca45661c3939f21c3bb3f405d08cfe1b35d7aa
Author: Mukund Sivaraman <muks@isc.org>
Date: Wed May 7 21:39:32 2014 +0530
Remove test for shortcut findnode()
The implementation was not included in this review branch, but the tests
erroneously made it through.
This functionality will be addressed in a different ticket (RT#35906).
commit 94ff14576ab3407f2612d34727b7eacfefc3668c
Author: Mukund Sivaraman <muks@isc.org>
Date: Wed May 7 21:36:50 2014 +0530
Minor indent fix
commit 50972f17697bb222996e433faa8224843366f9b2
Author: Evan Hunt <each@isc.org>
Date: Tue May 6 20:05:21 2014 -0700
[rt35904] style
commit 5c4d5d41fcc5bfecdeebc008896974385c841b8d
Author: Mukund Sivaraman <muks@isc.org>
Date: Sun May 4 19:19:36 2014 +0530
RBT related updates
* Add various RBT unit tests
* Add some helper methods useful in unit testing RBT code
* General cleanup
