Avoid pulling in sio.c that is not used by lwipovpn

sio.c is problematic on FreeBSD (and OpenBSD).

Also add hacky workaround for OpenBSD to compile by ignoring macro
redefinitions.

CMakeLists.txt

@@ -44,9 +44,26 @@ set(LWIP_OVPN_INCLUDE_DIRS
 set(THREADS_PREFER_PTHREAD_FLAG ON)
 find_package(Threads REQUIRED)
 
-# Have a warning about missing FreeBSD support until the PR get merged and we update our submodule
-if (${CMAKE_SYSTEM_NAME} STREQUAL "FreeBSD")
-    message(INFO "Note for FreeBSD support manually apply/checkout https://github.com/lwip-tcpip/lwip/pull/46 to the lwip submodule")
+# add a variant of lwipcontribportunix that does not include the probelmatic sio.c and to avoid pulling in unneeded sources
+add_library(lwipcontribunixsys EXCLUDE_FROM_ALL ${lwipcontribportunix_SRCS})
+target_include_directories(lwipcontribunixsys PRIVATE ${LWIP_INCLUDE_DIRS} ${LWIP_MBEDTLS_INCLUDE_DIRS})
+target_compile_options(lwipcontribunixsys PRIVATE ${LWIP_COMPILER_FLAGS})
+target_compile_definitions(lwipcontribunixsys PRIVATE ${LWIP_DEFINITIONS} ${LWIP_MBEDTLS_DEFINITIONS})
+target_link_libraries(lwipcontribunixsys PUBLIC ${LWIP_MBEDTLS_LINK_LIBRARIES})
+target_link_libraries(lwipcontribunixsys PUBLIC Threads::Threads)
+
+# Avoid format specifies type 'unsigned long' but the argument has type 'clock_t' (aka 'int') warning
+target_compile_options(lwipcontribunixsys PRIVATE -Wno-format)
+
+if (CMAKE_SYSTEM_NAME STREQUAL "Linux")
+    find_library(LIBUTIL util)
+    find_library(LIBRT rt)
+    target_link_libraries(lwipcontribunixsys PUBLIC ${LIBUTIL} ${LIBPTHREAD} ${LIBRT})
+endif()
+
+if (CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+    find_library(LIBUTIL util)
+    target_link_libraries(lwipcontribunixsys PUBLIC ${LIBUTIL})
 endif()
 
 
@@ -72,5 +89,11 @@ target_compile_definitions(lwipovpn PRIVATE ${LWIP_DEFINITIONS} ${LWIP_MBEDTLS_D
 if (NOT "${HAVE_ARC4RANDOM}")
     target_compile_definitions(lwipovpn PRIVATE -DARC4RANDOM_MISSING)
 endif()
-target_link_libraries(lwipovpn PRIVATE ${LWIP_SANITIZER_LIBS} lwipcontribexamples lwipcontribapps lwipcontribaddons lwipallapps lwipcontribportunix lwipcore lwipmbedtls)
-target_link_libraries(lwipovpn PRIVATE Threads::Threads)
+target_link_libraries(lwipovpn PRIVATE ${LWIP_SANITIZER_LIBS} lwipcontribexamples lwipcontribapps lwipcontribaddons lwipallapps lwipcontribunixsys lwipcore lwipmbedtls)
+
+
+# Ignore htons redefined error
+if (CMAKE_SYSTEM_NAME STREQUAL "OpenBSD")
+    target_compile_options(lwipcontribunixsys PRIVATE -Wno-macro-redefined)
+    target_compile_options(lwipovpn PRIVATE -Wno-macro-redefined)
+endif ()

netif/unixaf.c

@@ -27,18 +27,14 @@
  *
  * This file is part of the lwIP TCP/IP stack.
  *
- * Author: Adam Dunkels <adam@sics.se>
- *
  */
 
 #include <fcntl.h>
-#include <stdlib.h>
 #include <stdio.h>
-#include <unistd.h>
 #include <string.h>
-#include <sys/time.h>
 #include <stdbool.h>
 
+
 #include "lwip/opt.h"
 
 #include "lwip/debug.h"
@@ -47,7 +43,6 @@
 #include "lwip/snmp.h"
 #include "lwip/pbuf.h"
 #include "lwip/sys.h"
-#include "lwip/timeouts.h"
 #include "netif/etharp.h"
 #include "lwip/ethip6.h"
 

netif/unixaf.h

@@ -33,6 +33,8 @@
 #ifndef LWIP_UNIXAF_H
 #define LWIP_UNIXAF_H
 
+#include <stdbool.h>
+
 #include "lwip/netif.h"
 
 #ifdef __cplusplus