Compatibility for kernel version 3

nf_wrapper.h

@@ -0,0 +1,92 @@
+/**
+ * Thanks https://github.com/NICMx/Jool/blob/5f60dcda5944b01cc43c3be342aad26af8161bcb/include/nat64/mod/common/nf_wrapper.h for mapped kernel versions
+ */
+#ifndef _JOOL_MOD_NF_WRAPPER_H
+#define _JOOL_MOD_NF_WRAPPER_H
+
+/**
+ * @file
+ * The kernel API is far from static. In particular, the Netfilter packet entry
+ * function keeps changing. nf_hook.c, the file where we declare our packet
+ * entry function, has been quite difficult to read for a while now. It's pretty
+ * amusing, because we don't even use any of the noisy arguments.
+ *
+ * This file declares a usable function header that abstracts away all those
+ * useless arguments.
+ */
+
+#include <linux/version.h>
+
+/* If this is a Red Hat-based kernel (Red Hat, CentOS, Fedora, etc)... */
+#ifdef RHEL_RELEASE_CODE
+
+#if RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(7, 2)
+#define NF_CALLBACK(name, skb) unsigned int name( \
+		const struct nf_hook_ops *ops, \
+		struct sk_buff *skb, \
+		const struct net_device *in, \
+		const struct net_device *out, \
+		const struct nf_hook_state *state) \
+
+#elif RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(7, 0)
+#define NF_CALLBACK(name, skb) unsigned int name( \
+		const struct nf_hook_ops *ops, \
+		struct sk_buff *skb, \
+		const struct net_device *in, \
+		const struct net_device *out, \
+		int (*okfn)(struct sk_buff *))
+
+#else
+
+/*
+ * Sorry, I don't have headers for RHEL 6 and below because I'm in a bit of a
+ * deadline right now.
+ * If this is causing you trouble, find `nf_hookfn` in your kernel headers
+ * (typically in include/linux/netfilter.h) and add your version of the
+ * NF_CALLBACK macro here.
+ * Also, kernel headers per version can be found here: http://vault.centos.org/
+ */
+#error "Sorry; this version of RHEL is not supported because it's kind of old."
+
+#endif /* RHEL_RELEASE_CODE >= x */
+
+
+/* If this NOT a RedHat-based kernel (Ubuntu, Debian, SuSE, etc)... */
+#else
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 4, 0)
+#define NF_CALLBACK(name, skb) unsigned int name( \
+		void *priv, \
+		struct sk_buff *skb, \
+		const struct nf_hook_state *state)
+
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(4, 1, 0)
+#define NF_CALLBACK(name, skb) unsigned int name( \
+		const struct nf_hook_ops *ops, \
+		struct sk_buff *skb, \
+		const struct nf_hook_state *state)
+
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(3, 13, 0)
+#define NF_CALLBACK(name, skb) unsigned int name( \
+		const struct nf_hook_ops *ops, \
+		struct sk_buff *skb, \
+		const struct net_device *in, \
+		const struct net_device *out, \
+		int (*okfn)(struct sk_buff *))
+
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(3, 0, 0)
+#define NF_CALLBACK(name, skb) unsigned int name( \
+		unsigned int hooknum, \
+		struct sk_buff *skb, \
+		const struct net_device *in, \
+		const struct net_device *out, \
+		int (*okfn)(struct sk_buff *))
+
+#else
+#error "Linux < 3.0 isn't supported at all."
+
+#endif /* LINUX_VERSION_CODE > n */
+
+#endif /* RHEL or not RHEL */
+
+#endif /* _JOOL_MOD_NF_WRAPPER_H */