[PATCH 17/28] gss_krb5: import functionality to derive keys into the kernel

[Chuck Lever]

On Mar 31, 2008, at 11:59 AM, J. Bruce Fields wrote:
> On Mon, Mar 31, 2008 at 11:54:53AM -0400, Chuck Lever wrote:
>> On Mar 31, 2008, at 10:32 AM, Kevin Coffman wrote:
>>> +/*
>>> + * Constants used for key derivation
>>> + */
>>> +/* for 3DES */
>>> +#define KG_USAGE_SEAL 22
>>> +#define KG_USAGE_SIGN 23
>>> +#define KG_USAGE_SEQ  24
>>> +
>>> +/* from rfc3961 */
>>> +#define KEY_USAGE_SEED_CHECKSUM         0x99
>>> +#define KEY_USAGE_SEED_ENCRYPTION       0xAA
>>> +#define KEY_USAGE_SEED_INTEGRITY        0x55
>>> +
>>> +/* from rfc4121 */
>>> +#define KG_USAGE_ACCEPTOR_SEAL  22
>>> +#define KG_USAGE_ACCEPTOR_SIGN  23
>>> +#define KG_USAGE_INITIATOR_SEAL 24
>>> +#define KG_USAGE_INITIATOR_SIGN 25
>>> +
>>
>> I like adding parentheses around integers as a defensive coding  
>> tactic.
>
> What does it defend against?

The C compiler's macro interpreter is dumb.  Without the parentheses,  
unanticipated combinations can result from nesting, concatenation, or  
multiple evaluation.  The parentheses make token boundaries precisely  
clear.

--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com