| /* |
| * 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 <syslog.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; |
| |
| memset(&nb, 0, sizeof(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 |
| }; |