#
# Find the native netlink includes and library
#
# If they exist, differentiate between versions 1, 2 and 3.
# Version 1 does not have netlink/version.h
# Version 2 started separating libraries (libnl{,-genl,-route}).
# Version 3 (>= 3.2) started appending the major version number as suffix to
# library names (libnl-3)
#
#  NL_INCLUDE_DIRS - where to find libnl.h, etc.
#  NL_LIBRARIES    - List of libraries when using libnl.
#  NL_FOUND        - True if libnl found.

if(NL_LIBRARIES AND NL_INCLUDE_DIRS)
	# in cache already
	SET(NL_FOUND TRUE)
else()
	SET( SEARCHPATHS
			/opt/local
			/sw
			/usr
			/usr/local
			)

	find_package(PkgConfig)
	pkg_check_modules(NL3 libnl-3.0 libnl-genl-3.0 libnl-route-3.0)
	if(NOT NL3_FOUND)
		pkg_search_module(NL2 libnl-2.0)
	endif()

	# Try to find NL 2.0, 3.0 or 3.1 (/usr/include/netlink/version.h) or
	# NL >= 3.2 (/usr/include/libnl3/netlink/version.h)
	find_path(NL3_INCLUDE_DIR
			PATH_SUFFIXES
			include/libnl3
			include
			NAMES
			netlink/version.h
			HINTS
			"${NL3_libnl-3.0_INCLUDEDIR}"
			"${NL2_INCLUDEDIR}"
			PATHS
			$(SEARCHPATHS)
			)
	# NL version >= 2
	if(NL3_INCLUDE_DIR)
		find_library(NL3_LIBRARY
				NAMES
				nl-3 nl
				PATH_SUFFIXES
				lib64 lib
				HINTS
				"${NL3_libnl-3.0_LIBDIR}"
				"${NL2_LIBDIR}"
				PATHS
				$(SEARCHPATHS)
				)
		find_library(NLGENL_LIBRARY
				NAMES
				nl-genl-3 nl-genl
				PATH_SUFFIXES
				lib64 lib
				HINTS
				"${NL3_libnl-genl-3.0_LIBDIR}"
				"${NL2_LIBDIR}"
				PATHS
				$(SEARCHPATHS)
				)
		find_library(NLROUTE_LIBRARY
				NAMES
				nl-route-3 nl-route
				PATH_SUFFIXES
				lib64 lib
				HINTS
				"${NL3_libnl-route-3.0_LIBDIR}"
				"${NL2_LIBDIR}"
				PATHS
				$(SEARCHPATHS)
				)
		#
		# If we don't have all of those libraries, we can't use libnl.
		#
		if(NL3_LIBRARY AND NLGENL_LIBRARY AND NLROUTE_LIBRARY)
			set(NL_LIBRARY ${NL3_LIBRARY})
			if(NL3_INCLUDE_DIR)
				# NL2 and NL3 are similar and just affect how the version is reported in
				# the --version output. In cast of doubt, assume NL3 since a library
				# without version number could be any of 2.0, 3.0 or 3.1.
				if(NOT NL3_FOUND AND NL2_FOUND)
					set(HAVE_LIBNL2 1)
				else()
					set(HAVE_LIBNL3 1)
				endif()
			endif()
		endif()
		set(NL_INCLUDE_DIR ${NL3_INCLUDE_DIR})
	endif()

	# libnl-2 and libnl-3 not found, try NL version 1
	if(NOT (NL_LIBRARY AND NL_INCLUDE_DIR))
		pkg_search_module(NL1 libnl-1)
		find_path(NL1_INCLUDE_DIR
				NAMES
				netlink/netlink.h
				HINTS
				"${NL1_INCLUDEDIR}"
				PATHS
				$(SEARCHPATHS)
				)
		find_library(NL1_LIBRARY
				NAMES
				nl
				PATH_SUFFIXES
				lib64 lib
				HINTS
				"${NL1_LIBDIR}"
				PATHS
				$(SEARCHPATHS)
				)
		set(NL_LIBRARY ${NL1_LIBRARY})
		set(NL_INCLUDE_DIR ${NL1_INCLUDE_DIR})
		if(NL1_LIBRARY AND NL1_INCLUDE_DIR)
			set(HAVE_LIBNL1 1)
		endif()
	endif()
endif()
# MESSAGE(STATUS "LIB Found: ${NL_LIBRARY}, Suffix: ${NLSUFFIX}\n  1:${HAVE_LIBNL1}, 2:${HAVE_LIBNL2}, 3:${HAVE_LIBNL3}.")

# handle the QUIETLY and REQUIRED arguments and set NL_FOUND to TRUE if
# all listed variables are TRUE
INCLUDE(FindPackageHandleStandardArgs)
FIND_PACKAGE_HANDLE_STANDARD_ARGS(NL DEFAULT_MSG NL_LIBRARY NL_INCLUDE_DIR)

IF(NL_FOUND)
	set(NL_LIBRARIES ${NLGENL_LIBRARY} ${NLROUTE_LIBRARY} ${NL_LIBRARY})
	set(NL_INCLUDE_DIRS ${NL_INCLUDE_DIR})
	set(HAVE_LIBNL 1)
else()
	set(NL_LIBRARIES )
	set(NL_INCLUDE_DIRS)
endif()

MARK_AS_ADVANCED( NL_LIBRARIES NL_INCLUDE_DIRS )

