#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs_struct.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#include <linux/sysrq.h>
#include <linux/timer.h>
#include <linux/time.h>
#include <linux/lglock.h>
#include <linux/init.h>
#include <linux/idr.h>
#include <linux/namei.h>
#include <linux/bitops.h>
#include <linux/mount.h>
#include <linux/dcache.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/kprobes.h>
#include <linux/kallsyms.h>
#include <linux/nsproxy.h>
#include <net/sock.h>
#include <linux/inetdevice.h>

#define VERSION_STR "0.0.1"

#ifndef CONFIG_X86_64
#error "This code does not support your architecture"
#endif

MODULE_AUTHOR("Sapan Bhatia <sapanb@cs.princeton.edu>");
MODULE_DESCRIPTION("Transparent port forwarding for LXC.");
MODULE_LICENSE("GPL");
MODULE_VERSION(VERSION_STR);

static int address_in_root(unsigned int haddr) {
    printk(KERN_CRIT "In address_in_root: %d",haddr);
    struct net_device *dev;
    struct net *net = &init_net;

    for_each_netdev(net, dev) {
            unsigned int ifhaddr = inet_select_addr(dev,0,0);
            printk(KERN_CRIT "Checking address: %d",ifhaddr);
            if (haddr == ifhaddr) return 1;
    }
    return 0;
}

static int inet_bind_entry(struct socket *sock, struct sockaddr *uaddr, int addr_len) {
    struct sockaddr_in *addr = (struct sockaddr_in *)uaddr;
    unsigned int snum = ntohs(addr->sin_addr.s_addr);
    if (address_in_root(snum)) {
        put_net(sock_net(sock->sk));
        sock_net_set(sock->sk, get_net(&init_net)); 
        printk(KERN_CRIT "Rewiring netns");
    }
    jprobe_return();
    return 0;
}


static struct jprobe net_probe = {
	.entry = (kprobe_opcode_t *) inet_bind_entry
};


static void __exit transforward_exit(void)
{
	unregister_jprobe(&net_probe);
	printk("Transforward: Stopped transforward.\n");
}



static int __init transforward_init(void)
{
    int ret = 0;
	printk("Transforward: starting transforward version %s.\n",
	       VERSION_STR);
          net_probe.kp.addr = 
                  (kprobe_opcode_t *) kallsyms_lookup_name("inet_bind");
          if (!net_probe.kp.addr) {
                  printk("Couldn't find %s to plant kretprobe\n", "inet_bind");
                  return -1;
          }
  
          if ((ret = register_jprobe(&net_probe)) <0) {
                  printk("register_jprobe failed, returned %d\n", ret);
                  return -1;
          }
          printk("Planted jprobe at %p, handler addr %p\n",
                 net_probe.kp.addr, net_probe.entry);

        return ret;
}

module_init(transforward_init);
module_exit(transforward_exit);