/*

 * em_nbyte.c		N-Byte Ematch

 *

 *		This program is free software; you can distribute it and/or

 *		modify it under the terms of the GNU General Public License

 *		as published by the Free Software Foundation; either version

 *		2 of the License, or (at your option) any later version.

 *

 * Authors:	Thomas Graf <tgraf@suug.ch>

 */

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <fcntl.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <string.h>

#include <errno.h>

#include "m_ematch.h"

#include <linux/tc_ematch/tc_em_nbyte.h>

extern struct ematch_util nbyte_ematch_util;

static void nbyte_print_usage(FILE *fd)

{

	fprintf(fd,

	    "Usage: nbyte(NEEDLE at OFFSET [layer LAYER])\n" \

	    "where: NEEDLE := { string | \"c-escape-sequence\" }\n" \

	    "       OFFSET := int\n" \

	    "       LAYER  := { link | network | transport | 0..%d }\n" \

	    "\n" \

	    "Example: nbyte(\"ababa\" at 12 layer 1)\n",

	    TCF_LAYER_MAX);

}

static int nbyte_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr,

			    struct bstr *args)

{

	struct bstr *a;

	struct bstr *needle = args;

	unsigned long offset = 0, layer = TCF_LAYER_NETWORK;

	int offset_present = 0;

	struct tcf_em_nbyte nb = {};

#define PARSE_ERR(CARG, FMT, ARGS...) \

	em_parse_error(EINVAL, args, CARG, &nbyte_ematch_util, FMT, ##ARGS)

	if (args == NULL)

		return PARSE_ERR(args, "nbyte: missing arguments");

	if (needle->len <= 0)

		return PARSE_ERR(args, "nbyte: needle length is 0");

	for (a = bstr_next(args); a; a = bstr_next(a)) {

		if (!bstrcmp(a, "at")) {

			if (a->next == NULL)

				return PARSE_ERR(a, "nbyte: missing argument");

			a = bstr_next(a);

			offset = bstrtoul(a);

			if (offset == ULONG_MAX)

				return PARSE_ERR(a, "nbyte: invalid offset, " \

				    "must be numeric");

			offset_present = 1;

		} else if (!bstrcmp(a, "layer")) {

			if (a->next == NULL)

				return PARSE_ERR(a, "nbyte: missing argument");

			a = bstr_next(a);

			layer = parse_layer(a);

			if (layer == INT_MAX) {

				layer = bstrtoul(a);

				if (layer == ULONG_MAX)

					return PARSE_ERR(a, "nbyte: invalid " \

					    "layer");

			}

			if (layer > TCF_LAYER_MAX)

				return PARSE_ERR(a, "nbyte: illegal layer, " \

				    "must be in 0..%d", TCF_LAYER_MAX);

		} else

			return PARSE_ERR(a, "nbyte: unknown parameter");

	}

	if (offset_present == 0)

		return PARSE_ERR(a, "nbyte: offset required");

	nb.len = needle->len;

	nb.layer = (__u8) layer;

	nb.off = (__u16) offset;

	addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));

	addraw_l(n, MAX_MSG, &nb, sizeof(nb));

	addraw_l(n, MAX_MSG, needle->data, needle->len);

#undef PARSE_ERR

	return 0;

}

static int nbyte_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,

			    int data_len)

{

	int i;

	struct tcf_em_nbyte *nb = data;

	__u8 *needle;

	if (data_len < sizeof(*nb)) {

		fprintf(stderr, "NByte header size mismatch\n");

		return -1;

	}

	if (data_len < sizeof(*nb) + nb->len) {

		fprintf(stderr, "NByte payload size mismatch\n");

		return -1;

	}

	needle = data + sizeof(*nb);

	for (i = 0; i < nb->len; i++)

		fprintf(fd, "%02x ", needle[i]);

	fprintf(fd, "\"");

	for (i = 0; i < nb->len; i++)

		fprintf(fd, "%c", isprint(needle[i]) ? needle[i] : '.');

	fprintf(fd, "\" at %d layer %d", nb->off, nb->layer);

	return 0;

}

struct ematch_util nbyte_ematch_util = {

	.kind = "nbyte",

	.kind_num = TCF_EM_NBYTE,

	.parse_eopt = nbyte_parse_eopt,

	.print_eopt = nbyte_print_eopt,

	.print_usage = nbyte_print_usage

};