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141 lines
3.4 KiB
C
141 lines
3.4 KiB
C
/*
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* em_nbyte.c N-Byte Ematch
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*
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* This program is free software; you can distribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <string.h>
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#include <errno.h>
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#include "m_ematch.h"
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#include <linux/tc_ematch/tc_em_nbyte.h>
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extern struct ematch_util nbyte_ematch_util;
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static void nbyte_print_usage(FILE *fd)
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{
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fprintf(fd,
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"Usage: nbyte(NEEDLE at OFFSET [layer LAYER])\n" \
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"where: NEEDLE := { string | \"c-escape-sequence\" }\n" \
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" OFFSET := int\n" \
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" LAYER := { link | network | transport | 0..%d }\n" \
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"\n" \
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"Example: nbyte(\"ababa\" at 12 layer 1)\n",
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TCF_LAYER_MAX);
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}
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static int nbyte_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr,
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struct bstr *args)
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{
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struct bstr *a;
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struct bstr *needle = args;
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unsigned long offset = 0, layer = TCF_LAYER_NETWORK;
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int offset_present = 0;
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struct tcf_em_nbyte nb = {};
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#define PARSE_ERR(CARG, FMT, ARGS...) \
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em_parse_error(EINVAL, args, CARG, &nbyte_ematch_util, FMT, ##ARGS)
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if (args == NULL)
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return PARSE_ERR(args, "nbyte: missing arguments");
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if (needle->len <= 0)
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return PARSE_ERR(args, "nbyte: needle length is 0");
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for (a = bstr_next(args); a; a = bstr_next(a)) {
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if (!bstrcmp(a, "at")) {
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if (a->next == NULL)
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return PARSE_ERR(a, "nbyte: missing argument");
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a = bstr_next(a);
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offset = bstrtoul(a);
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if (offset == ULONG_MAX)
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return PARSE_ERR(a, "nbyte: invalid offset, " \
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"must be numeric");
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offset_present = 1;
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} else if (!bstrcmp(a, "layer")) {
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if (a->next == NULL)
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return PARSE_ERR(a, "nbyte: missing argument");
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a = bstr_next(a);
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layer = parse_layer(a);
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if (layer == INT_MAX) {
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layer = bstrtoul(a);
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if (layer == ULONG_MAX)
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return PARSE_ERR(a, "nbyte: invalid " \
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"layer");
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}
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if (layer > TCF_LAYER_MAX)
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return PARSE_ERR(a, "nbyte: illegal layer, " \
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"must be in 0..%d", TCF_LAYER_MAX);
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} else
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return PARSE_ERR(a, "nbyte: unknown parameter");
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}
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if (offset_present == 0)
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return PARSE_ERR(a, "nbyte: offset required");
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nb.len = needle->len;
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nb.layer = (__u8) layer;
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nb.off = (__u16) offset;
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addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));
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addraw_l(n, MAX_MSG, &nb, sizeof(nb));
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addraw_l(n, MAX_MSG, needle->data, needle->len);
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#undef PARSE_ERR
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return 0;
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}
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static int nbyte_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,
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int data_len)
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{
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int i;
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struct tcf_em_nbyte *nb = data;
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__u8 *needle;
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if (data_len < sizeof(*nb)) {
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fprintf(stderr, "NByte header size mismatch\n");
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return -1;
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}
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if (data_len < sizeof(*nb) + nb->len) {
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fprintf(stderr, "NByte payload size mismatch\n");
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return -1;
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}
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needle = data + sizeof(*nb);
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for (i = 0; i < nb->len; i++)
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fprintf(fd, "%02x ", needle[i]);
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fprintf(fd, "\"");
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for (i = 0; i < nb->len; i++)
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fprintf(fd, "%c", isprint(needle[i]) ? needle[i] : '.');
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fprintf(fd, "\" at %d layer %d", nb->off, nb->layer);
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return 0;
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}
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struct ematch_util nbyte_ematch_util = {
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.kind = "nbyte",
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.kind_num = TCF_EM_NBYTE,
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.parse_eopt = nbyte_parse_eopt,
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.print_eopt = nbyte_print_eopt,
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.print_usage = nbyte_print_usage
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};
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