HP-UX C SIP Stack Programmer's Guide (Novembery 2007)

342 HP-UX C SIP Stack Programmer’s Guide

DNS Caching

DNS CACHING

OMPILATION FLAGS

Several compilation flags are used to configure the DNS caching feature. All the

compilation flags are located in the common/config/rvusrconfig.h file and are

described below:

RV_DNS_USES_CACHING

To enable caching, the RV_DNS_USES_CACHING compile time constant

should be set to RV_YES.

RV_DNS_CACHE_HASH_SIZE

Cache lookup is implemented using static open hashing. The size of hash table

is given by the compile time constant, RV_DNS_CACHE_HASH_SIZE.

RV_DNS_CACHE_PAGE_SIZE

All memory needed for caching is pre-allocated statically on initialization. The

actual data is kept on memory pages. The page size (in bytes) is determined by

the compile time constant, RV_DNS_CACHE_PAGE_SIZE, and should be

>= 512. If the page size is too small to accommodate a single DNS record, this

record will not be cached.

DNS_CACHE_PAGES_NUMBER

The number of pages used for caching data is given by

RV_DNS_CACHE_PAGES_NUMBER. There is no lower limit on the number

of pages, but if the number of pages is too low, new records will not be cached.

RV_DNS_USES_HOSTS

When DNS caching is enabled, the DNS module can be configured to look for

host name resolution in the operating system host file (/etc/hosts for example).

To instruct the SIP Stack to search the host file, the RV_DNS_USES_HOSTS

should be set to RV_TRUE.