#include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/proc_fs.h>
  #include <linux/skbuff.h>
  #include <linux/netfilter.h>

  #include <linux/seq_file.h>

  #include <net/protocol.h>

  #include <net/netfilter/nf_log.h>

  
  #include "nf_internals.h"

  /* Internal logging interface, which relies on the real

     LOG target modules */
  
  #define NF_LOG_PREFIXLEN		128

  #define NFLOGGER_NAME_LEN		64

  static const struct nf_logger __rcu *nf_loggers[NFPROTO_NUMPROTO] __read_mostly;

  static struct list_head nf_loggers_l[NFPROTO_NUMPROTO] __read_mostly;

  static DEFINE_MUTEX(nf_log_mutex);

  static struct nf_logger *__find_logger(int pf, const char *str_logger)

  {

  	struct nf_logger *t;

  	list_for_each_entry(t, &nf_loggers_l[pf], list[pf]) {
  		if (!strnicmp(str_logger, t->name, strlen(t->name)))
  			return t;
  	}

  	return NULL;

  }

  /* return EEXIST if the same logger is registred, 0 on success. */
  int nf_log_register(u_int8_t pf, struct nf_logger *logger)

  {

  	const struct nf_logger *llog;

  	int i;

  	if (pf >= ARRAY_SIZE(nf_loggers))

  		return -EINVAL;

  	for (i = 0; i < ARRAY_SIZE(logger->list); i++)
  		INIT_LIST_HEAD(&logger->list[i]);

  	mutex_lock(&nf_log_mutex);

  
  	if (pf == NFPROTO_UNSPEC) {

  		for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
  			list_add_tail(&(logger->list[i]), &(nf_loggers_l[i]));
  	} else {
  		/* register at end of list to honor first register win */
  		list_add_tail(&logger->list[pf], &nf_loggers_l[pf]);

  		llog = rcu_dereference_protected(nf_loggers[pf],
  						 lockdep_is_held(&nf_log_mutex));
  		if (llog == NULL)

  			rcu_assign_pointer(nf_loggers[pf], logger);
  	}

  	mutex_unlock(&nf_log_mutex);

  	return 0;

  }

  EXPORT_SYMBOL(nf_log_register);

  void nf_log_unregister(struct nf_logger *logger)

  {

  	const struct nf_logger *c_logger;

  	int i;

  	mutex_lock(&nf_log_mutex);

  	for (i = 0; i < ARRAY_SIZE(nf_loggers); i++) {

  		c_logger = rcu_dereference_protected(nf_loggers[i],
  						     lockdep_is_held(&nf_log_mutex));
  		if (c_logger == logger)

  			rcu_assign_pointer(nf_loggers[i], NULL);

  		list_del(&logger->list[i]);

  	}

  	mutex_unlock(&nf_log_mutex);

  	synchronize_rcu();

  }

  EXPORT_SYMBOL(nf_log_unregister);

  int nf_log_bind_pf(u_int8_t pf, const struct nf_logger *logger)
  {

  	if (pf >= ARRAY_SIZE(nf_loggers))
  		return -EINVAL;

  	mutex_lock(&nf_log_mutex);
  	if (__find_logger(pf, logger->name) == NULL) {
  		mutex_unlock(&nf_log_mutex);
  		return -ENOENT;
  	}
  	rcu_assign_pointer(nf_loggers[pf], logger);
  	mutex_unlock(&nf_log_mutex);
  	return 0;
  }
  EXPORT_SYMBOL(nf_log_bind_pf);
  
  void nf_log_unbind_pf(u_int8_t pf)
  {

  	if (pf >= ARRAY_SIZE(nf_loggers))
  		return;

  	mutex_lock(&nf_log_mutex);
  	rcu_assign_pointer(nf_loggers[pf], NULL);
  	mutex_unlock(&nf_log_mutex);
  }
  EXPORT_SYMBOL(nf_log_unbind_pf);

  void nf_log_packet(u_int8_t pf,

  		   unsigned int hooknum,
  		   const struct sk_buff *skb,
  		   const struct net_device *in,
  		   const struct net_device *out,

  		   const struct nf_loginfo *loginfo,

  		   const char *fmt, ...)
  {
  	va_list args;
  	char prefix[NF_LOG_PREFIXLEN];

  	const struct nf_logger *logger;

  	rcu_read_lock();

  	logger = rcu_dereference(nf_loggers[pf]);

  	if (logger) {
  		va_start(args, fmt);
  		vsnprintf(prefix, sizeof(prefix), fmt, args);
  		va_end(args);

  		logger->logfn(pf, hooknum, skb, in, out, loginfo, prefix);

  	}
  	rcu_read_unlock();
  }
  EXPORT_SYMBOL(nf_log_packet);
  
  #ifdef CONFIG_PROC_FS
  static void *seq_start(struct seq_file *seq, loff_t *pos)
  {

  	mutex_lock(&nf_log_mutex);

  	if (*pos >= ARRAY_SIZE(nf_loggers))

  		return NULL;
  
  	return pos;
  }
  
  static void *seq_next(struct seq_file *s, void *v, loff_t *pos)
  {
  	(*pos)++;

  	if (*pos >= ARRAY_SIZE(nf_loggers))

  		return NULL;
  
  	return pos;
  }
  
  static void seq_stop(struct seq_file *s, void *v)
  {

  	mutex_unlock(&nf_log_mutex);

  }
  
  static int seq_show(struct seq_file *s, void *v)
  {
  	loff_t *pos = v;
  	const struct nf_logger *logger;

  	struct nf_logger *t;
  	int ret;

  	logger = nf_loggers[*pos];

  
  	if (!logger)

  		ret = seq_printf(s, "%2lld NONE (", *pos);
  	else
  		ret = seq_printf(s, "%2lld %s (", *pos, logger->name);
  
  	if (ret < 0)
  		return ret;

  	list_for_each_entry(t, &nf_loggers_l[*pos], list[*pos]) {
  		ret = seq_printf(s, "%s", t->name);

  		if (ret < 0)

  			return ret;

  		if (&t->list[*pos] != nf_loggers_l[*pos].prev) {
  			ret = seq_printf(s, ",");

  			if (ret < 0)

  				return ret;

  		}
  	}

  	return seq_printf(s, ")
  ");

  }

  static const struct seq_operations nflog_seq_ops = {

  	.start	= seq_start,
  	.next	= seq_next,
  	.stop	= seq_stop,
  	.show	= seq_show,
  };
  
  static int nflog_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &nflog_seq_ops);
  }

  static const struct file_operations nflog_file_ops = {

  	.owner	 = THIS_MODULE,
  	.open	 = nflog_open,
  	.read	 = seq_read,
  	.llseek	 = seq_lseek,
  	.release = seq_release,
  };

  #endif /* PROC_FS */

  #ifdef CONFIG_SYSCTL

  static struct ctl_path nf_log_sysctl_path[] = {

  	{ .procname = "net", },
  	{ .procname = "netfilter", },
  	{ .procname = "nf_log", },

  	{ }
  };
  
  static char nf_log_sysctl_fnames[NFPROTO_NUMPROTO-NFPROTO_UNSPEC][3];
  static struct ctl_table nf_log_sysctl_table[NFPROTO_NUMPROTO+1];
  static struct ctl_table_header *nf_log_dir_header;

  static int nf_log_proc_dostring(ctl_table *table, int write,

  			 void __user *buffer, size_t *lenp, loff_t *ppos)

  {
  	const struct nf_logger *logger;

  	char buf[NFLOGGER_NAME_LEN];
  	size_t size = *lenp;

  	int r = 0;
  	int tindex = (unsigned long)table->extra1;
  
  	if (write) {

  		if (size > sizeof(buf))
  			size = sizeof(buf);
  		if (copy_from_user(buf, buffer, size))
  			return -EFAULT;
  
  		if (!strcmp(buf, "NONE")) {

  			nf_log_unbind_pf(tindex);
  			return 0;
  		}
  		mutex_lock(&nf_log_mutex);

  		logger = __find_logger(tindex, buf);

  		if (logger == NULL) {
  			mutex_unlock(&nf_log_mutex);
  			return -ENOENT;
  		}
  		rcu_assign_pointer(nf_loggers[tindex], logger);
  		mutex_unlock(&nf_log_mutex);
  	} else {

  		mutex_lock(&nf_log_mutex);
  		logger = nf_loggers[tindex];

  		if (!logger)
  			table->data = "NONE";
  		else
  			table->data = logger->name;

  		r = proc_dostring(table, write, buffer, lenp, ppos);

  		mutex_unlock(&nf_log_mutex);

  	}
  
  	return r;
  }
  
  static __init int netfilter_log_sysctl_init(void)

  {

  	int i;

  
  	for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
  		snprintf(nf_log_sysctl_fnames[i-NFPROTO_UNSPEC], 3, "%d", i);

  		nf_log_sysctl_table[i].procname	=
  			nf_log_sysctl_fnames[i-NFPROTO_UNSPEC];
  		nf_log_sysctl_table[i].data = NULL;
  		nf_log_sysctl_table[i].maxlen =
  			NFLOGGER_NAME_LEN * sizeof(char);
  		nf_log_sysctl_table[i].mode = 0644;
  		nf_log_sysctl_table[i].proc_handler = nf_log_proc_dostring;
  		nf_log_sysctl_table[i].extra1 = (void *)(unsigned long) i;
  	}
  
  	nf_log_dir_header = register_sysctl_paths(nf_log_sysctl_path,
  				       nf_log_sysctl_table);
  	if (!nf_log_dir_header)
  		return -ENOMEM;
  
  	return 0;
  }
  #else
  static __init int netfilter_log_sysctl_init(void)
  {
  	return 0;
  }
  #endif /* CONFIG_SYSCTL */
  
  int __init netfilter_log_init(void)
  {
  	int i, r;

  #ifdef CONFIG_PROC_FS

  	if (!proc_create("nf_log", S_IRUGO,
  			 proc_net_netfilter, &nflog_file_ops))

  		return -1;

  #endif

  	/* Errors will trigger panic, unroll on error is unnecessary. */
  	r = netfilter_log_sysctl_init();
  	if (r < 0)
  		return r;

  	for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
  		INIT_LIST_HEAD(&(nf_loggers_l[i]));

  	return 0;
  }