Add configure check for signed or unsigned nfq_get_payload, adapt code.

configure.in

@@ -415,7 +415,26 @@ case $host in
     AC_CHECK_LIB([netfilter_queue], [nfq_set_queue_maxlen],AC_DEFINE_UNQUOTED([HAVE_NFQ_MAXLEN],[1],[Found queue max length support in netfilter_queue]) ,,[-lnfnetlink])
     AC_CHECK_LIB([netfilter_queue], [nfq_set_verdict2],AC_DEFINE_UNQUOTED([HAVE_NFQ_SET_VERDICT2],[1],[Found nfq_set_verdict2 function in netfilter_queue]) ,,[-lnfnetlink])
 
-
+    # check if the argument to nfq_get_payload is signed or unsigned
+    AC_MSG_CHECKING([for signed nfq_get_payload payload argument])
+    STORECFLAGS="${CFLAGS}"
+    CFLAGS="${CFLAGS} -Werror"
+    AC_COMPILE_IFELSE(
+            [AC_LANG_PROGRAM(
+                [
+                #include <libnetfilter_queue/libnetfilter_queue.h>
+                ],
+                [
+                char *pktdata;
+                nfq_get_payload(NULL, &pktdata);
+                ])],
+            [libnetfilter_queue_nfq_get_payload_signed="yes"],
+            [libnetfilter_queue_nfq_get_payload_signed="no"])
+    AC_MSG_RESULT($libnetfilter_queue_nfq_get_payload_signed)
+    if test "x$libnetfilter_queue_nfq_get_payload_signed" = "xyes"; then
+        AC_DEFINE([NFQ_GET_PAYLOAD_SIGNED], [], [For signed version of nfq_get_payload])
+    fi
+    CFLAGS="${STORECFLAGS}"
 ;;
 esac
 

src/source-nfq.c

@@ -260,7 +260,11 @@ int NFQSetupPkt (Packet *p, struct nfq_q_handle *qh, void *data)
     p->nfq_v.ifi  = nfq_get_indev(tb);
     p->nfq_v.ifo  = nfq_get_outdev(tb);
 
+#ifdef NFQ_GET_PAYLOAD_SIGNED
+    ret = nfq_get_payload(tb, &pktdata);
+#else
     ret = nfq_get_payload(tb, (unsigned char **) &pktdata);
+#endif /* NFQ_GET_PAYLOAD_SIGNED */
     if (ret > 0) {
         /* nfq_get_payload returns a pointer to a part of memory
          * that is not preserved over the lifetime of our packet.