netlink: Introduce support for netlink

This change introduces support for using AF_NETLINK sockets to talk to
the lwip stack, supporting RTM_GETLINK and RTM_GETADDR operations.

Co-authored-by: Simon Kuenzer <simon@unikraft.io>
Signed-off-by: Simon Kuenzer <simon@unikraft.io>
Signed-off-by: Andrei Tatar <ttr@unikraft.io>
Reviewed-by: Sergiu Moga <sergiu@unikraft.io>
Reviewed-by: Michalis Pappas <michalis@unikraft.io>
Approved-by: Michalis Pappas <michalis@unikraft.io>
GitHub-Closes: #69

Author: 2 people

Config.uk

@@ -4,6 +4,7 @@ menuconfig LIBLWIP
 	select LIBNOLIBC if !HAVE_LIBC
 	select LIBUKDEBUG
 	select LIBUKRANDOM
+	select LIBUKBITOPS if LIBPOSIX_NETLINK
 	select HAVE_NW_STACK
 
 if LIBLWIP

Makefile.uk

@@ -113,6 +113,7 @@ LIBLWIP_SRCS-$(CONFIG_LWIP_TCP) += $(LIBLWIP_EXTRACTED)/core/tcp.c
 LIBLWIP_SRCS-$(CONFIG_LWIP_TCP) += $(LIBLWIP_EXTRACTED)/core/tcp_in.c
 LIBLWIP_SRCS-$(CONFIG_LWIP_TCP) += $(LIBLWIP_EXTRACTED)/core/tcp_out.c
 LIBLWIP_SRCS-$(CONFIG_LWIP_UDP) += $(LIBLWIP_EXTRACTED)/core/udp.c
+LIBLWIP_SRCS-$(CONFIG_LIBPOSIX_NETLINK) += $(LIBLWIP_BASE)/netlink.c|unikraft
 
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 # APIs