cannot be compiled headers

[crazyshoes]

I get the error(s) message for net/if.h and resolve.h on an Apple OS X 10.4.6:
configure: WARNING: resolv.h: present but cannot be compiled
configure: WARNING: resolv.h: check for missing prerequisite headers?
configure: WARNING: resolv.h: see the Autoconf documentation
configure: WARNING: resolv.h: section "Present But Cannot Be Compiled"
configure: WARNING: resolv.h: proceeding with the preprocessor's result
configure: WARNING: resolv.h: in the future, the compiler will take precedence
configure: WARNING: ## ------------------------------------------ ##
configure: WARNING: ## Report this to the AC_PACKAGE_NAME lists. ##
configure: WARNING: ## ------------------------------------------ ##
checking for resolv.h... yes
and
configure: WARNING: net/if.h: present but cannot be compiled
configure: WARNING: net/if.h: check for missing prerequisite headers?
configure: WARNING: net/if.h: see the Autoconf documentation
configure: WARNING: net/if.h: section "Present But Cannot Be Compiled"
configure: WARNING: net/if.h: proceeding with the preprocessor's result
configure: WARNING: net/if.h: in the future, the compiler will take precedence
configure: WARNING: ## ------------------------------------------ ##
configure: WARNING: ## Report this to the AC_PACKAGE_NAME lists. ##
configure: WARNING: ## ------------------------------------------ ##
If I try a make it errors out with the following:
common/common.c: In function 'CHECK_DNS':
common/common.c:1870: error: 'PACKETSZ' undeclared (first use in this function)
common/common.c:1870: error: (Each undeclared identifier is reported only once
common/common.c:1870: error: for each function it appears in.)
make[4]: *** [common.o] Error 1
make[3]: *** [all-recursive] Error 1
make[2]: *** [all-recursive] Error 1
make[1]: *** [all-recursive] Error 1
make: *** [all-recursive] Error 1
anybody got some suggestions?
Any help would be extremely appreciated! Thanks!