1/* 2 * em_nbyte.c N-Byte Ematch 3 * 4 * This program is free software; you can distribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * Authors: Thomas Graf <tgraf@suug.ch> 10 */ 11 12#include <stdio.h> 13#include <stdlib.h> 14#include <unistd.h> 15#include <syslog.h> 16#include <fcntl.h> 17#include <sys/socket.h> 18#include <netinet/in.h> 19#include <arpa/inet.h> 20#include <string.h> 21#include <dlfcn.h> 22#include <errno.h> 23 24#include "m_ematch.h" 25#include <linux/tc_ematch/tc_em_nbyte.h> 26 27extern struct ematch_util nbyte_ematch_util; 28 29static void nbyte_print_usage(FILE *fd) 30{ 31 fprintf(fd, 32 "Usage: nbyte(NEEDLE at OFFSET [layer LAYER])\n" \ 33 "where: NEEDLE := { string | \"c-escape-sequence\" }\n" \ 34 " OFFSET := int\n" \ 35 " LAYER := { link | header | next-header | 0..%d }\n" \ 36 "\n" \ 37 "Example: nbyte(\"ababa\" at 12 layer 1)\n", 38 TCF_LAYER_MAX); 39} 40 41static int nbyte_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr, 42 struct bstr *args) 43{ 44 struct bstr *a; 45 struct bstr *needle = args; 46 unsigned long offset = 0, layer = TCF_LAYER_NETWORK; 47 int offset_present = 0; 48 struct tcf_em_nbyte nb; 49 50 memset(&nb, 0, sizeof(nb)); 51 52#define PARSE_ERR(CARG, FMT, ARGS...) \ 53 em_parse_error(EINVAL, args, CARG, &nbyte_ematch_util, FMT ,##ARGS) 54 55 if (args == NULL) 56 return PARSE_ERR(args, "nbyte: missing arguments"); 57 58 if (needle->len <= 0) 59 return PARSE_ERR(args, "nbyte: needle length is 0"); 60 61 for (a = bstr_next(args); a; a = bstr_next(a)) { 62 if (!bstrcmp(a, "at")) { 63 if (a->next == NULL) 64 return PARSE_ERR(a, "nbyte: missing argument"); 65 a = bstr_next(a); 66 67 offset = bstrtoul(a); 68 if (offset == ULONG_MAX) 69 return PARSE_ERR(a, "nbyte: invalid offset, " \ 70 "must be numeric"); 71 72 offset_present = 1; 73 } else if (!bstrcmp(a, "layer")) { 74 if (a->next == NULL) 75 return PARSE_ERR(a, "nbyte: missing argument"); 76 a = bstr_next(a); 77 78 layer = parse_layer(a); 79 if (layer == INT_MAX) { 80 layer = bstrtoul(a); 81 if (layer == ULONG_MAX) 82 return PARSE_ERR(a, "nbyte: invalid " \ 83 "layer"); 84 } 85 86 if (layer > TCF_LAYER_MAX) 87 return PARSE_ERR(a, "nbyte: illegal layer, " \ 88 "must be in 0..%d", TCF_LAYER_MAX); 89 } else 90 return PARSE_ERR(a, "nbyte: unknown parameter"); 91 } 92 93 if (offset_present == 0) 94 return PARSE_ERR(a, "nbyte: offset required"); 95 96 nb.len = needle->len; 97 nb.layer = (__u8) layer; 98 nb.off = (__u16) offset; 99 100 addraw_l(n, MAX_MSG, hdr, sizeof(*hdr)); 101 addraw_l(n, MAX_MSG, &nb, sizeof(nb)); 102 addraw_l(n, MAX_MSG, needle->data, needle->len); 103 104#undef PARSE_ERR 105 return 0; 106} 107 108static int nbyte_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data, 109 int data_len) 110{ 111 int i; 112 struct tcf_em_nbyte *nb = data; 113 __u8 *needle; 114 115 if (data_len < sizeof(*nb)) { 116 fprintf(stderr, "NByte header size mismatch\n"); 117 return -1; 118 } 119 120 if (data_len < sizeof(*nb) + nb->len) { 121 fprintf(stderr, "NByte payload size mismatch\n"); 122 return -1; 123 } 124 125 needle = data + sizeof(*nb); 126 127 for (i = 0; i < nb->len; i++) 128 fprintf(fd, "%02x ", needle[i]); 129 130 fprintf(fd, "\""); 131 for (i = 0; i < nb->len; i++) 132 fprintf(fd, "%c", isprint(needle[i]) ? needle[i] : '.'); 133 fprintf(fd, "\" at %d layer %d", nb->off, nb->layer); 134 135 return 0; 136} 137 138struct ematch_util nbyte_ematch_util = { 139 .kind = "nbyte", 140 .kind_num = TCF_EM_NBYTE, 141 .parse_eopt = nbyte_parse_eopt, 142 .print_eopt = nbyte_print_eopt, 143 .print_usage = nbyte_print_usage 144}; 145