qca-nss-ecm/ecm_state.c

/*
 **************************************************************************
 * Copyright (c) 2015, 2020-2021, The Linux Foundation.  All rights reserved.
 * Permission to use, copy, modify, and/or distribute this software for
 * any purpose with or without fee is hereby granted, provided that the
 * above copyright notice and this permission notice appear in all copies.
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 **************************************************************************
 */

#include <linux/version.h>
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/string.h>
#include <linux/debugfs.h>
#include <asm/unaligned.h>
#include <asm/uaccess.h>	/* for put_user */
#include <linux/inet.h>
#include <linux/ipv6.h>
#include <linux/netfilter_bridge.h>

/*
 * Debug output levels
 * 0 = OFF
 * 1 = ASSERTS / ERRORS
 * 2 = 1 + WARN
 * 3 = 2 + INFO
 * 4 = 3 + TRACE
 */
#define DEBUG_LEVEL ECM_STATE_DEBUG_LEVEL

#include "ecm_types.h"
#include "ecm_db_types.h"
#include "ecm_state.h"
#include "ecm_tracker.h"
#include "ecm_classifier.h"
#include "ecm_front_end_types.h"
#include "ecm_classifier_default.h"
#include "ecm_db.h"

/*
 * Magic numbers
 */
#define ECM_STATE_FILE_INSTANCE_MAGIC 0xB3FE

/*
 * Debugfs dentry object.
 */
static struct dentry *ecm_state_dentry;

/*
 * Locking of the state - concurrency control
 */
static DEFINE_SPINLOCK(ecm_state_lock);					/* Protect the table from SMP access. */

/*
 * Character device stuff - used to communicate status back to user space
 */
static int ecm_state_dev_major_id = 0;			/* Major ID of registered char dev from which we can dump out state to userspace */

/*
 * Buffer sizes
 */
#define ECM_STATE_FILE_PREFIX_SIZE 128
#define ECM_STATE_FILE_PREFIX_LEVELS_MAX 10
#define ECM_STATE_FILE_BUFFER_SIZE 32768

/*
 * Output selection flags
 */
#define ECM_STATE_FILE_OUTPUT_CONNECTIONS 1
#define ECM_STATE_FILE_OUTPUT_MAPPINGS 2
#define ECM_STATE_FILE_OUTPUT_HOSTS 4
#define ECM_STATE_FILE_OUTPUT_NODES 8
#define ECM_STATE_FILE_OUTPUT_INTERFACES 16
#define ECM_STATE_FILE_OUTPUT_CONNECTIONS_CHAIN 32
#define ECM_STATE_FILE_OUTPUT_MAPPINGS_CHAIN 64
#define ECM_STATE_FILE_OUTPUT_HOSTS_CHAIN 128
#define ECM_STATE_FILE_OUTPUT_NODES_CHAIN 256
#define ECM_STATE_FILE_OUTPUT_INTERFACES_CHAIN 512
#define ECM_STATE_FILE_OUTPUT_PROTOCOL_COUNTS 1024
#ifdef ECM_DB_CTA_TRACK_ENABLE
#define ECM_STATE_FILE_OUTPUT_CLASSIFIER_TYPE_ASSIGNMENTS 2048
#endif

/*
 * struct ecm_state_file_instance
 *	Structure used as state per open instance of our db state file
 */
struct ecm_state_file_instance {
	int output_mask;				/* The content types wanted by the user */
	struct ecm_db_connection_instance *ci;		/* All connections list iterator */
	struct ecm_db_mapping_instance *mi;		/* All mappings list iterator */
	struct ecm_db_host_instance *hi;		/* All hosts list iterator */
	struct ecm_db_node_instance *ni;		/* All nodes list iterator */
	struct ecm_db_iface_instance *ii;		/* All interfaces list iterator */
#ifdef ECM_DB_CTA_TRACK_ENABLE
	struct ecm_db_connection_instance *classifier_type_assignments[ECM_CLASSIFIER_TYPES];
							/* Classifier type connection assignments iterator, one for each classifier type */
#endif
	int connection_hash_index;			/* Connection hash table lengths iterator */
	int mapping_hash_index;				/* Mapping hash table lengths iterator */
	int host_hash_index;				/* Host hash table lengths iterator */
	int node_hash_index;				/* Node hash table lengths iterator */
	int iface_hash_index;				/* Interface hash table lengths iterator */
	int protocol;					/* Protocol connection count iterator */

	char prefix[ECM_STATE_FILE_PREFIX_SIZE];	/* This is the prefix added to every message written */
	int prefix_levels[ECM_STATE_FILE_PREFIX_LEVELS_MAX];
							/* How many nested prefixes supported */
	int prefix_level;				/* Prefix nest level */

	char msg[ECM_STATE_FILE_BUFFER_SIZE];		/* The message written / being returned to the reader */
	char *msgp;					/* Points into the msg buffer as we output it to the reader piece by piece */
	int msg_len;					/* Length of the msg buffer still to be written out */
#if (DEBUG_LEVEL > 0)
	uint16_t magic;
#endif
};
static int ecm_state_file_output_mask = ECM_STATE_FILE_OUTPUT_CONNECTIONS;
							/* Bit mask specifies which data to output in the state file */

/*
 * ecm_state_write_reset()
 *	Reset the msg buffer, specifying a new initial prefix
 *
 * Returns 0 on success
 */
int ecm_state_write_reset(struct ecm_state_file_instance *sfi, char *prefix)
{
	int result;

	DEBUG_CHECK_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC, "%px: magic failed", sfi);
	sfi->msgp = sfi->msg;
	sfi->msg_len = 0;

	result = snprintf(sfi->prefix, ECM_STATE_FILE_PREFIX_SIZE, "%s", prefix);
	if ((result < 0) || (result >= ECM_STATE_FILE_PREFIX_SIZE)) {
		return -1;
	}
	sfi->prefix_level = 0;
	sfi->prefix_levels[sfi->prefix_level] = result;
	return 0;
}

/*
 * ecm_state_prefix_add()
 *	Add another level to the prefix
 *
 * Returns 0 on success
 */
int ecm_state_prefix_add(struct ecm_state_file_instance *sfi, char *prefix)
{
	int pxsz;
	int pxremain;
	int result;

	DEBUG_CHECK_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC, "%px: magic failed", sfi);

	pxsz = sfi->prefix_levels[sfi->prefix_level];
	pxremain = ECM_STATE_FILE_PREFIX_SIZE - pxsz;
	result = snprintf(sfi->prefix + pxsz, pxremain, ".%s", prefix);
	if ((result < 0) || (result >= pxremain)) {
		return -1;
	}

	sfi->prefix_level++;
	DEBUG_ASSERT(sfi->prefix_level < ECM_STATE_FILE_PREFIX_LEVELS_MAX, "Bad prefix handling\n");
	sfi->prefix_levels[sfi->prefix_level] = pxsz + result;
	return 0;
}

/*
 * ecm_state_prefix_index_add()
 *	Add another level (numeric) to the prefix
 *
 * Returns 0 on success
 */
int ecm_state_prefix_index_add(struct ecm_state_file_instance *sfi, uint32_t index)
{
	int pxsz;
	int pxremain;
	int result;

	DEBUG_CHECK_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC, "%px: magic failed", sfi);

	pxsz = sfi->prefix_levels[sfi->prefix_level];
	pxremain = ECM_STATE_FILE_PREFIX_SIZE - pxsz;
	result = snprintf(sfi->prefix + pxsz, pxremain, ".%u", index);
	if ((result < 0) || (result >= pxremain)) {
		return -1;
	}

	sfi->prefix_level++;
	DEBUG_ASSERT(sfi->prefix_level < ECM_STATE_FILE_PREFIX_LEVELS_MAX, "Bad prefix handling\n");
	sfi->prefix_levels[sfi->prefix_level] = pxsz + result;
	return 0;
}

/*
 * ecm_state_prefix_remove()
 *	Remove level from the prefix
 *
 * Returns 0 on success
 */
int ecm_state_prefix_remove(struct ecm_state_file_instance *sfi)
{
	int pxsz;

	DEBUG_CHECK_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC, "%px: magic failed", sfi);

	sfi->prefix_level--;
	DEBUG_ASSERT(sfi->prefix_level >= 0, "Bad prefix handling\n");
	pxsz = sfi->prefix_levels[sfi->prefix_level];
	sfi->prefix[pxsz] = 0;
	return 0;
}

/*
 * ecm_state_write()
 *	Write out to the message buffer, prefix is added automatically.
 *
 * Returns 0 on success
 */
int ecm_state_write(struct ecm_state_file_instance *sfi, char *name, char *fmt, ...)
{
	int remain;
	char *ptr;
	int result;
	va_list args;

	DEBUG_CHECK_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC, "%px: magic failed", sfi);

	remain = ECM_STATE_FILE_BUFFER_SIZE - sfi->msg_len;
	ptr = sfi->msg + sfi->msg_len;
	result = snprintf(ptr, remain, "%s.%s=", sfi->prefix, name);
	if ((result < 0) || (result >= remain)) {
		return -1;
	}

	sfi->msg_len += result;
	remain -= result;
	ptr += result;

	va_start(args, fmt);
	result = vsnprintf(ptr, remain, fmt, args);
	va_end(args);
	if ((result < 0) || (result >= remain)) {
		return -2;
	}

	sfi->msg_len += result;
	remain -= result;
	ptr += result;

	result = snprintf(ptr, remain, "\n");
	if ((result < 0) || (result >= remain)) {
		return -3;
	}

	sfi->msg_len += result;
	return 0;
}

/*
 * ecm_state_char_dev_conn_msg_prep()
 *	Prepare a connection message
 */
static bool ecm_state_char_dev_conn_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;

	DEBUG_TRACE("%px: Prep conn msg for %px\n", sfi, sfi->ci);

	if ((result = ecm_state_write_reset(sfi, "conns"))) {
		return result;
	}
	return ecm_db_connection_state_get(sfi, sfi->ci);
}

/*
 * ecm_state_char_dev_mapping_msg_prep()
 *	Prepare a mapping message
 */
static bool ecm_state_char_dev_mapping_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;

	DEBUG_TRACE("%px: Prep mapping msg for %px\n", sfi, sfi->mi);

	if ((result = ecm_state_write_reset(sfi, "mappings"))) {
		return result;
	}
	return ecm_db_mapping_state_get(sfi, sfi->mi);
}

/*
 * ecm_state_char_dev_host_msg_prep()
 *	Prepare a host message
 */
static bool ecm_state_char_dev_host_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;

	DEBUG_TRACE("%px: Prep host msg for %px\n", sfi, sfi->hi);

	if ((result = ecm_state_write_reset(sfi, "hosts"))) {
		return result;
	}

	return ecm_db_host_state_get(sfi, sfi->hi);
}

/*
 * ecm_state_char_dev_node_msg_prep()
 *	Prepare a node message
 */
static bool ecm_state_char_dev_node_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;

	DEBUG_TRACE("%px: Prep node msg for %px\n", sfi, sfi->ni);

	if ((result = ecm_state_write_reset(sfi, "nodes"))) {
		return result;
	}

	return ecm_db_node_state_get(sfi, sfi->ni);
}

/*
 * ecm_state_char_dev_iface_msg_prep()
 *	Prepare an interface message
 */
static int ecm_state_char_dev_iface_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;

	DEBUG_TRACE("%px: Prep iface msg for %px\n", sfi, sfi->ii);

	if ((result = ecm_state_write_reset(sfi, "ifaces"))) {
		return result;
	}
	return ecm_db_iface_state_get(sfi, sfi->ii);
}

/*
 * ecm_state_char_dev_conn_chain_msg_prep()
 *	Generate an conn hash table chain message
 */
static bool ecm_state_char_dev_conn_chain_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;
	int chain_len;
	DEBUG_TRACE("%px: Prep conn chain msg\n", sfi);

	/*
	 * Get hash table chain length
	 */
	chain_len = ecm_db_connection_hash_table_lengths_get(sfi->connection_hash_index);

	if ((result = ecm_state_write_reset(sfi, "conn_chain"))) {
		return result;
	}
	if ((result = ecm_state_prefix_index_add(sfi, sfi->connection_hash_index))) {
		return result;
	}
	return ecm_state_write(sfi, "length", "%d", chain_len);
}

/*
 * ecm_state_char_dev_mapping_chain_msg_prep()
 *	Generate an mapping hash table chain message
 */
static bool ecm_state_char_dev_mapping_chain_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;
	int chain_len;
	DEBUG_TRACE("%px: Prep mapping chain msg\n", sfi);

	/*
	 * Get hash table chain length
	 */
	chain_len = ecm_db_mapping_hash_table_lengths_get(sfi->mapping_hash_index);

	if ((result = ecm_state_write_reset(sfi, "mapping_chain"))) {
		return result;
	}
	if ((result = ecm_state_prefix_index_add(sfi, sfi->mapping_hash_index))) {
		return result;
	}
	return ecm_state_write(sfi, "length", "%d", chain_len);
}

/*
 * ecm_state_char_dev_host_chain_msg_prep()
 *	Generate an host hash table chain message
 */
static bool ecm_state_char_dev_host_chain_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;
	int chain_len;
	DEBUG_TRACE("%px: Prep host chain msg\n", sfi);

	/*
	 * Get hash table chain length
	 */
	chain_len = ecm_db_host_hash_table_lengths_get(sfi->host_hash_index);

	if ((result = ecm_state_write_reset(sfi, "host_chain"))) {
		return result;
	}
	if ((result = ecm_state_prefix_index_add(sfi, sfi->host_hash_index))) {
		return result;
	}
	return ecm_state_write(sfi, "length", "%d", chain_len);
}

/*
 * ecm_state_char_dev_node_chain_msg_prep()
 *	Generate an node hash table chain message
 */
static bool ecm_state_char_dev_node_chain_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;
	int chain_len;
	DEBUG_TRACE("%px: Prep node chain msg\n", sfi);

	/*
	 * Get hash table chain length
	 */
	chain_len = ecm_db_node_hash_table_lengths_get(sfi->node_hash_index);

	if ((result = ecm_state_write_reset(sfi, "node_chain"))) {
		return result;
	}
	if ((result = ecm_state_prefix_index_add(sfi, sfi->node_hash_index))) {
		return result;
	}
	return ecm_state_write(sfi, "length", "%d", chain_len);
}

/*
 * ecm_state_char_dev_iface_chain_msg_prep()
 *	Generate an interface hash table chain message
 */
static bool ecm_state_char_dev_iface_chain_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;
	int chain_len;
	DEBUG_TRACE("%px: Prep iface chain msg\n", sfi);

	/*
	 * Get hash table chain length
	 */
	chain_len = ecm_db_iface_hash_table_lengths_get(sfi->iface_hash_index);

	if ((result = ecm_state_write_reset(sfi, "iface_chain"))) {
		return result;
	}
	if ((result = ecm_state_prefix_index_add(sfi, sfi->iface_hash_index))) {
		return result;
	}
	return ecm_state_write(sfi, "length", "%d", chain_len);
}

/*
 * ecm_state_char_dev_protocol_count_msg_prep()
 *	Generate a protocol usage message
 */
static bool ecm_state_char_dev_protocol_count_msg_prep(struct ecm_state_file_instance *sfi)
{
	int result;
	int count;
	DEBUG_TRACE("%px: Prep protocol msg\n", sfi);

	/*
	 * Get protocol connection total count
	 */
	count = ecm_db_connection_count_by_protocol_get(sfi->protocol);

	if ((result = ecm_state_write_reset(sfi, "protocol"))) {
		return result;
	}
	if ((result = ecm_state_prefix_index_add(sfi, sfi->protocol))) {
		return result;
	}
	return ecm_state_write(sfi, "connections", "%d", count);
}

#ifdef ECM_DB_CTA_TRACK_ENABLE
/*
 * ecm_state_char_dev_cta_msg_prep()
 *	Generate a classifier type assignment message
 */
static int ecm_state_char_dev_cta_msg_prep(struct ecm_state_file_instance *sfi, ecm_classifier_type_t ca_type)
{
	struct ecm_db_connection_instance *ci;
	int result;

	DEBUG_TRACE("%px: Prep classifier type assignment msg: %d\n", sfi, ca_type);

	ci = sfi->classifier_type_assignments[ca_type];
	if (!ci) {
		return 0;
	}

	if ((result = ecm_state_write_reset(sfi, "cta"))) {
		return result;
	}
	if ((result = ecm_state_prefix_index_add(sfi, ca_type))) {
		return result;
	}
	if ((result = ecm_state_write(sfi, "conn.serial", "%u", ecm_db_connection_serial_get(ci)))) {
		return result;
	}

	/*
	 * Prep next connection for when we are called again, releasing this one.
	 */
	sfi->classifier_type_assignments[ca_type] = ecm_db_connection_by_classifier_type_assignment_get_and_ref_next(ci, ca_type);
	ecm_db_connection_by_classifier_type_assignment_deref(ci, ca_type);
	return 0;
}

/*
 * ecm_state_file_classifier_type_assignments_release()
 *	Releases any uniterated classifier assignments
 */
static void ecm_state_file_classifier_type_assignments_release(struct ecm_state_file_instance *sfi)
{
	ecm_classifier_type_t ca_type;

	for (ca_type = 0; ca_type < ECM_CLASSIFIER_TYPES; ++ca_type) {
		struct ecm_db_connection_instance *ci;

		ci = sfi->classifier_type_assignments[ca_type];
		if (!ci) {
			continue;
		}

		ecm_db_connection_by_classifier_type_assignment_deref(ci, ca_type);
	}
}
#endif

/*
 * ecm_state_char_device_open()
 *	Opens the special char device file which we use to dump our state.
 */
static int ecm_state_char_device_open(struct inode *inode, struct file *file)
{
	struct ecm_state_file_instance *sfi;

	DEBUG_INFO("State open\n");

	/*
	 * Allocate state information for the reading
	 */
	DEBUG_ASSERT(file->private_data == NULL, "unexpected double open: %px?\n", file->private_data);

	sfi = (struct ecm_state_file_instance *)kzalloc(sizeof(struct ecm_state_file_instance), GFP_ATOMIC | __GFP_NOWARN);
	if (!sfi) {
		return -ENOMEM;
	}
	DEBUG_SET_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC);
	file->private_data = sfi;

	/*
	 * Snapshot output mask for this file
	 */
	spin_lock_bh(&ecm_state_lock);
	sfi->output_mask = ecm_state_file_output_mask;
	spin_unlock_bh(&ecm_state_lock);

	/*
	 * Get the first indicies for hash and protocol stats should they be needed.
	 * NOTE: There are no references held here so it does not matter to get them all even if they are not wanted.
	 */
	sfi->connection_hash_index = ecm_db_connection_hash_index_get_first();
	sfi->mapping_hash_index = ecm_db_mapping_hash_index_get_first();
	sfi->host_hash_index = ecm_db_host_hash_index_get_first();
	sfi->node_hash_index = ecm_db_node_hash_index_get_first();
	sfi->iface_hash_index = ecm_db_iface_hash_index_get_first();
	sfi->protocol = ecm_db_protocol_get_first();

	/*
	 * Take references to each object list that we are going to generate state for.
	 */
	if (sfi->output_mask & ECM_STATE_FILE_OUTPUT_CONNECTIONS) {
		sfi->ci = ecm_db_connections_get_and_ref_first();
	}
	if (sfi->output_mask & ECM_STATE_FILE_OUTPUT_MAPPINGS) {
		sfi->mi = ecm_db_mappings_get_and_ref_first();
	}
	if (sfi->output_mask & ECM_STATE_FILE_OUTPUT_HOSTS) {
		sfi->hi = ecm_db_hosts_get_and_ref_first();
	}
	if (sfi->output_mask & ECM_STATE_FILE_OUTPUT_NODES) {
		sfi->ni = ecm_db_nodes_get_and_ref_first();
	}
	if (sfi->output_mask & ECM_STATE_FILE_OUTPUT_INTERFACES) {
		sfi->ii = ecm_db_interfaces_get_and_ref_first();
	}
#ifdef ECM_DB_CTA_TRACK_ENABLE
	if (sfi->output_mask & ECM_STATE_FILE_OUTPUT_CLASSIFIER_TYPE_ASSIGNMENTS) {
		ecm_classifier_type_t ca_type;

		/*
		 * Iterate all classifier type assignments.
		 * Hold the head of each list to start us off on our iterating process.
		 */
		for (ca_type = 0; ca_type < ECM_CLASSIFIER_TYPES; ++ca_type) {
			sfi->classifier_type_assignments[ca_type] = ecm_db_connection_by_classifier_type_assignment_get_and_ref_first(ca_type);
		}
	}
#endif

	DEBUG_INFO("State opened %px\n", sfi);

	return 0;
}

/*
 * ecm_state_char_device_release()
 *	Called when a process closes the device file.
 */
static int ecm_state_char_device_release(struct inode *inode, struct file *file)
{
	struct ecm_state_file_instance *sfi;

	sfi = (struct ecm_state_file_instance *)file->private_data;
	DEBUG_CHECK_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC, "%px: magic failed", sfi);
	DEBUG_INFO("%px: State close\n", sfi);

	/*
	 * Release any references held
	 */
	if (sfi->ci) {
		ecm_db_connection_deref(sfi->ci);
	}
	if (sfi->mi) {
		ecm_db_mapping_deref(sfi->mi);
	}
	if (sfi->hi) {
		ecm_db_host_deref(sfi->hi);
	}
	if (sfi->ni) {
		ecm_db_node_deref(sfi->ni);
	}
	if (sfi->ii) {
		ecm_db_iface_deref(sfi->ii);
	}
#ifdef ECM_DB_CTA_TRACK_ENABLE
	ecm_state_file_classifier_type_assignments_release(sfi);
#endif

	DEBUG_CLEAR_MAGIC(sfi);
	kfree(sfi);

	return 0;
}

/*
 * ecm_state_char_device_read()
 *	Called to read the state
 */
static ssize_t ecm_state_char_device_read(struct file *file,	/* see include/linux/fs.h   */
			   char *buffer,				/* buffer to fill with data */
			   size_t length,				/* length of the buffer     */
			   loff_t *offset)				/* Doesn't apply - this is a char file */
{
	struct ecm_state_file_instance *sfi;
	int bytes_read = 0;						/* Number of bytes actually written to the buffer */
#ifdef ECM_DB_CTA_TRACK_ENABLE
	ecm_classifier_type_t ca_type;
#endif

	sfi = (struct ecm_state_file_instance *)file->private_data;
	DEBUG_CHECK_MAGIC(sfi, ECM_STATE_FILE_INSTANCE_MAGIC, "%px: magic failed", sfi);
	DEBUG_TRACE("%px: State read up to length %d bytes\n", sfi, (int)length);

	/*
	 * If there is still some message remaining to be output then complete that first
	 */
	if (sfi->msg_len) {
		goto char_device_read_output;
	}

	if (sfi->ci) {
		struct ecm_db_connection_instance *cin;
		if (ecm_state_char_dev_conn_msg_prep(sfi)) {
			return -EIO;
		}

		/*
		 * Next connection for when we return
		 */
		cin = ecm_db_connection_get_and_ref_next(sfi->ci);
		ecm_db_connection_deref(sfi->ci);
		sfi->ci = cin;

		goto char_device_read_output;
	}

	if (sfi->mi) {
		struct ecm_db_mapping_instance *min;
		if (ecm_state_char_dev_mapping_msg_prep(sfi)) {
			return -EIO;
		}

		/*
		 * Next mapping for when we return
		 */
		min = ecm_db_mapping_get_and_ref_next(sfi->mi);
		ecm_db_mapping_deref(sfi->mi);
		sfi->mi = min;

		goto char_device_read_output;
	}

	if (sfi->hi) {
		struct ecm_db_host_instance *hin;
		if (ecm_state_char_dev_host_msg_prep(sfi)) {
			return -EIO;
		}

		/*
		 * Next host for when we return
		 */
		hin = ecm_db_host_get_and_ref_next(sfi->hi);
		ecm_db_host_deref(sfi->hi);
		sfi->hi = hin;

		goto char_device_read_output;
	}

	if (sfi->ni) {
		struct ecm_db_node_instance *nin;
		if (ecm_state_char_dev_node_msg_prep(sfi)) {
			return -EIO;
		}

		/*
		 * Next node for when we return
		 */
		nin = ecm_db_node_get_and_ref_next(sfi->ni);
		ecm_db_node_deref(sfi->ni);
		sfi->ni = nin;

		goto char_device_read_output;
	}

	if (sfi->ii) {
		struct ecm_db_iface_instance *iin;
		if (ecm_state_char_dev_iface_msg_prep(sfi)) {
			return -EIO;
		}

		/*
		 * Next iface for when we return
		 */
		iin = ecm_db_interface_get_and_ref_next(sfi->ii);
		ecm_db_iface_deref(sfi->ii);
		sfi->ii = iin;

		goto char_device_read_output;
	}

	if ((sfi->output_mask & ECM_STATE_FILE_OUTPUT_CONNECTIONS_CHAIN) && (sfi->connection_hash_index >= 0)) {
		if (ecm_state_char_dev_conn_chain_msg_prep(sfi)) {
			return -EIO;
		}
		sfi->connection_hash_index = ecm_db_connection_hash_index_get_next(sfi->connection_hash_index);
		goto char_device_read_output;
	}

	if ((sfi->output_mask & ECM_STATE_FILE_OUTPUT_MAPPINGS_CHAIN) && (sfi->mapping_hash_index >= 0)) {
		if (ecm_state_char_dev_mapping_chain_msg_prep(sfi)) {
			return -EIO;
		}
		sfi->mapping_hash_index = ecm_db_mapping_hash_index_get_next(sfi->mapping_hash_index);
		goto char_device_read_output;
	}

	if ((sfi->output_mask & ECM_STATE_FILE_OUTPUT_HOSTS_CHAIN) && (sfi->host_hash_index >= 0)) {
		if (ecm_state_char_dev_host_chain_msg_prep(sfi)) {
			return -EIO;
		}
		sfi->host_hash_index = ecm_db_host_hash_index_get_next(sfi->host_hash_index);
		goto char_device_read_output;
	}

	if ((sfi->output_mask & ECM_STATE_FILE_OUTPUT_NODES_CHAIN) && (sfi->node_hash_index >= 0)) {
		if (ecm_state_char_dev_node_chain_msg_prep(sfi)) {
			return -EIO;
		}
		sfi->node_hash_index = ecm_db_node_hash_index_get_next(sfi->node_hash_index);
		goto char_device_read_output;
	}

	if ((sfi->output_mask & ECM_STATE_FILE_OUTPUT_INTERFACES_CHAIN) && (sfi->iface_hash_index >= 0)) {
		if (ecm_state_char_dev_iface_chain_msg_prep(sfi)) {
			return -EIO;
		}
		sfi->iface_hash_index = ecm_db_iface_hash_index_get_next(sfi->iface_hash_index);
		goto char_device_read_output;
	}

	if ((sfi->output_mask & ECM_STATE_FILE_OUTPUT_PROTOCOL_COUNTS) && (sfi->protocol >= 0)) {
		if (ecm_state_char_dev_protocol_count_msg_prep(sfi)) {
			return -EIO;
		}
		sfi->protocol = ecm_db_protocol_get_next(sfi->protocol);
		goto char_device_read_output;
	}

#ifdef ECM_DB_CTA_TRACK_ENABLE
	for (ca_type = 0; ca_type < ECM_CLASSIFIER_TYPES; ++ca_type) {
		if (!sfi->classifier_type_assignments[ca_type]) continue;
		if (ecm_state_char_dev_cta_msg_prep(sfi, ca_type)) {
			return -EIO;
		}
		goto char_device_read_output;
	}
#endif

	/*
	 * EOF
	 */
	return 0;

char_device_read_output:

	/*
	 * If supplied buffer is small we limit what we output
	 */
	bytes_read = sfi->msg_len;
	if (bytes_read > length) {
		bytes_read = length;
	}
	if (copy_to_user(buffer, sfi->msgp, bytes_read)) {
		return -EIO;
	}
	sfi->msg_len -= bytes_read;
	sfi->msgp += bytes_read;

	DEBUG_TRACE("State read done, bytes_read %d bytes\n", bytes_read);

	/*
	 * Most read functions return the number of bytes put into the buffer
	 */
	return bytes_read;
}

/*
 * ecm_state_char_device_write()
 */
static ssize_t ecm_state_char_device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
{
	return -EINVAL;
}

/*
 * File operations used in the char device
 *	NOTE: The char device is a simple file that allows us to dump our connection tracking state
 */
static struct file_operations ecm_state_fops = {
	.read = ecm_state_char_device_read,
	.write = ecm_state_char_device_write,
	.open = ecm_state_char_device_open,
	.release = ecm_state_char_device_release
};

/*
 * ecm_state_init()
 */
int ecm_state_init(struct dentry *dentry)
{
	int result = -1;
	DEBUG_INFO("ECM State init\n");

	ecm_state_dentry = debugfs_create_dir("ecm_state", dentry);
	if (!ecm_state_dentry) {
		DEBUG_ERROR("Failed to create ecm state directory in debugfs\n");
		return -1;
	}

	if (!debugfs_create_u32("state_dev_major", S_IRUGO, ecm_state_dentry,
					(u32 *)&ecm_state_dev_major_id)) {
		DEBUG_ERROR("Failed to create ecm state dev major file in debugfs\n");
		goto init_cleanup;
	}

	if (!debugfs_create_u32("state_file_output_mask", S_IRUGO | S_IWUSR, ecm_state_dentry,
					(u32 *)&ecm_state_file_output_mask)) {
		DEBUG_ERROR("Failed to create ecm state output mask file in debugfs\n");
		goto init_cleanup;
	}

	/*
	 * Register a char device that we will use to provide a dump of our state
	 */
	result = register_chrdev(0, "ecm_state", &ecm_state_fops);
	if (result < 0) {
                DEBUG_ERROR("Failed to register chrdev %d\n", result);
		goto init_cleanup;
	}
	ecm_state_dev_major_id = result;
	DEBUG_TRACE("registered chr dev major id assigned %d\n", ecm_state_dev_major_id);

	return 0;

init_cleanup:

	debugfs_remove_recursive(ecm_state_dentry);
	return result;
}

/*
 * ecm_state_exit()
 */
void ecm_state_exit(void)
{
	DEBUG_INFO("ECM State exit\n");

	unregister_chrdev(ecm_state_dev_major_id, "ecm_state");

	/*
	 * Remove the debugfs files recursively.
	 */
	if (ecm_state_dentry) {
		debugfs_remove_recursive(ecm_state_dentry);
	}
}