[RFC 3/3] MPEG2/TS drop analyzer file: libxt_mp2t.c

[Jesper Dangaard Brouer <hawk@diku.dk>]

/*
  * Userspace interface for MPEG2 TS match extension "mp2t" for Xtables.
  *
  * Copyright (c) Jesper Dangaard Brouer <jdb@comx.dk>, 2009+
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License; either
  * version 2 of the License, or any later version, as published by the
  * Free Software Foundation.
  *
  */

#include <getopt.h>
#include <netdb.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stddef.h>

#include <xtables.h>
#include "xt_mp2t.h"

/*
  * Userspace iptables/xtables interface for mp2t module.
  */

/* FIXME: don't think this compat check does not cover all versions */
#ifndef XTABLES_VERSION
#define xtables_error exit_error
#endif

static const struct option mp2t_mt_opts[] = {
 	{.name = "name",	.has_arg = true,  .val = 'n'},
 	{.name = "drop",	.has_arg = false, .val = 'd'},
 	{.name = "drop-detect",	.has_arg = false, .val = 'd'},
 	{.name = "max",		.has_arg = true,  .val = 'x'},
 	{.name = "max-streams",	.has_arg = true,  .val = 'x'},
 	{NULL},
};

static void mp2t_mt_help(void)
{
 	printf(
"mp2t (MPEG2 Transport Stream) match options:\n"
"VERSION %s\n"
"   [--name <name>]        Name for proc file /proc/net/xt_mp2t/rule_NAME\n"
"   [--drop-detect]        Match lost TS frames (occured before this packet)\n"
"   [--max-streams <num>]  Track 'max' number of streams (per rule)\n",
 		version
 		);
}

static void mp2t_mt_init(struct xt_entry_match *match)
{
 	struct xt_mp2t_mtinfo *info = (void *)match->data;
 	/* Enable drop detection per default */
 	info->flags = XT_MP2T_DETECT_DROP;
}

static int mp2t_mt_parse(int c, char **argv, int invert, unsigned int *flags,
 			 const void *entry, struct xt_entry_match **match)
{
 	struct xt_mp2t_mtinfo *info = (void *)(*match)->data;
 	u_int32_t num;

 	switch (c) {
 	case 'n': /* --name */
 		xtables_param_act(XTF_ONLY_ONCE, "mp2t", "--name",
 				  *flags & XT_MP2T_PARAM_NAME);
 		if (invert)
 			xtables_error(PARAMETER_PROBLEM, "Inverting name?");
 		if (strlen(optarg) == 0)
 			xtables_error(PARAMETER_PROBLEM, "Zero-length name?");
 		if (strchr(optarg, '"') != NULL)
 			xtables_error(PARAMETER_PROBLEM,
 				      "Illegal character in name (\")!");
 		strncpy(info->rule_name, optarg, sizeof(info->rule_name));
 		info->flags |= XT_MP2T_PARAM_NAME;
 		*flags |= XT_MP2T_PARAM_NAME;
 		break;

 	case 'd': /* --drop-detect */
 		if (*flags & XT_MP2T_DETECT_DROP)
 			xtables_error(PARAMETER_PROBLEM,
 				      "Can't specify --drop option twice");
 		*flags |= XT_MP2T_DETECT_DROP;

 		if (invert)
 			info->flags &= ~XT_MP2T_DETECT_DROP;
 		else
 			info->flags |= XT_MP2T_DETECT_DROP;

 		break;

 	case 'x': /* --max-streams */
 		if (*flags & XT_MP2T_MAX_STREAMS)
 			xtables_error(PARAMETER_PROBLEM,
 				"Can't specify --max-streams option twice");
 		*flags |= XT_MP2T_MAX_STREAMS;

 		if (invert) {
 			info->cfg.max = 0;
 			/* printf("inverted\n"); */
 			break;
 		}

 		/* OLD iptables style
 		if (string_to_number(optarg, 0, 0xffffffff, &num) == -1)
 			xtables_error(PARAMETER_PROBLEM,
 				      "bad --max-stream: `%s'", optarg);
 		*/

 		/* C-style
 		char *end;
 		num = strtoul(optarg, &end, 0);
 		*/

 		/* New xtables style */
 		if (!xtables_strtoui(optarg, NULL, &num, 0, UINT32_MAX))
 			xtables_error(PARAMETER_PROBLEM,
 				      "bad --max-stream: `%s'", optarg);

 		/* DEBUG: printf("--max-stream=%lu\n", num); */
 		info->flags |= XT_MP2T_MAX_STREAMS;
 		info->cfg.max = num;

 		break;

 	default:
 		return false;
 	}

 	return true;
}

static void mp2t_mt_print(const void *entry,
 			  const struct xt_entry_match *match, int numeric)
{
 	const struct xt_mp2t_mtinfo *info = (const void *)(match->data);

 	/* Always indicate this is a mp2t match rule */
 	printf("mp2t match");

 	if (info->flags & XT_MP2T_PARAM_NAME)
 		printf(" name:\"%s\"", info->rule_name);

 	if (!(info->flags & XT_MP2T_DETECT_DROP))
 		printf(" !drop-detect");

 	if (info->flags & XT_MP2T_MAX_STREAMS)
 		printf(" max-streams:%u ", info->cfg.max);
}

static void mp2t_mt_save(const void *entry,
 			 const struct xt_entry_match *match)
{
 	const struct xt_mp2t_mtinfo *info = (const void *)(match->data);

 	/* We need to handle --name, --drop-detect, and --max-streams. */
 	if (info->flags & XT_MP2T_PARAM_NAME)
 		printf("--name \"%s\" ",  info->rule_name);

 	if (!(info->flags & XT_MP2T_DETECT_DROP))
 		printf("! --drop-detect ");

 	if (info->flags & XT_MP2T_MAX_STREAMS)
 		printf("--max-streams %u ", info->cfg.max);

}

static struct xtables_match mp2t_mt_reg = {
 	.version        = XTABLES_VERSION,
 	.name           = "mp2t",
 	.revision       = 0,
 	.family         = PF_UNSPEC,
 	.size           = XT_ALIGN(sizeof(struct xt_mp2t_mtinfo)),
 	.userspacesize  = offsetof(struct xt_mp2t_mtinfo, hinfo),
 	.init           = mp2t_mt_init,
 	.help           = mp2t_mt_help,
 	.parse          = mp2t_mt_parse,
/*	.final_check    = mp2t_mt_check,*/
 	.print          = mp2t_mt_print,
 	.save           = mp2t_mt_save,
 	.extra_opts     = mp2t_mt_opts,
};

static void _init(void)
{
 	xtables_register_match(&mp2t_mt_reg);
}