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/*
* 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
};
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