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 (at) 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 <errno.h> 22 23 #include "m_ematch.h" 24 #include <linux/tc_ematch/tc_em_nbyte.h> 25 26 extern struct ematch_util nbyte_ematch_util; 27 28 static void nbyte_print_usage(FILE *fd) 29 { 30 fprintf(fd, 31 "Usage: nbyte(NEEDLE at OFFSET [layer LAYER])\n" \ 32 "where: NEEDLE := { string | \"c-escape-sequence\" }\n" \ 33 " OFFSET := int\n" \ 34 " LAYER := { link | network | transport | 0..%d }\n" \ 35 "\n" \ 36 "Example: nbyte(\"ababa\" at 12 layer 1)\n", 37 TCF_LAYER_MAX); 38 } 39 40 static int nbyte_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr, 41 struct bstr *args) 42 { 43 struct bstr *a; 44 struct bstr *needle = args; 45 unsigned long offset = 0, layer = TCF_LAYER_NETWORK; 46 int offset_present = 0; 47 struct tcf_em_nbyte nb; 48 49 memset(&nb, 0, sizeof(nb)); 50 51 #define PARSE_ERR(CARG, FMT, ARGS...) \ 52 em_parse_error(EINVAL, args, CARG, &nbyte_ematch_util, FMT ,##ARGS) 53 54 if (args == NULL) 55 return PARSE_ERR(args, "nbyte: missing arguments"); 56 57 if (needle->len <= 0) 58 return PARSE_ERR(args, "nbyte: needle length is 0"); 59 60 for (a = bstr_next(args); a; a = bstr_next(a)) { 61 if (!bstrcmp(a, "at")) { 62 if (a->next == NULL) 63 return PARSE_ERR(a, "nbyte: missing argument"); 64 a = bstr_next(a); 65 66 offset = bstrtoul(a); 67 if (offset == ULONG_MAX) 68 return PARSE_ERR(a, "nbyte: invalid offset, " \ 69 "must be numeric"); 70 71 offset_present = 1; 72 } else if (!bstrcmp(a, "layer")) { 73 if (a->next == NULL) 74 return PARSE_ERR(a, "nbyte: missing argument"); 75 a = bstr_next(a); 76 77 layer = parse_layer(a); 78 if (layer == INT_MAX) { 79 layer = bstrtoul(a); 80 if (layer == ULONG_MAX) 81 return PARSE_ERR(a, "nbyte: invalid " \ 82 "layer"); 83 } 84 85 if (layer > TCF_LAYER_MAX) 86 return PARSE_ERR(a, "nbyte: illegal layer, " \ 87 "must be in 0..%d", TCF_LAYER_MAX); 88 } else 89 return PARSE_ERR(a, "nbyte: unknown parameter"); 90 } 91 92 if (offset_present == 0) 93 return PARSE_ERR(a, "nbyte: offset required"); 94 95 nb.len = needle->len; 96 nb.layer = (__u8) layer; 97 nb.off = (__u16) offset; 98 99 addraw_l(n, MAX_MSG, hdr, sizeof(*hdr)); 100 addraw_l(n, MAX_MSG, &nb, sizeof(nb)); 101 addraw_l(n, MAX_MSG, needle->data, needle->len); 102 103 #undef PARSE_ERR 104 return 0; 105 } 106 107 static int nbyte_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data, 108 int data_len) 109 { 110 int i; 111 struct tcf_em_nbyte *nb = data; 112 __u8 *needle; 113 114 if (data_len < sizeof(*nb)) { 115 fprintf(stderr, "NByte header size mismatch\n"); 116 return -1; 117 } 118 119 if (data_len < sizeof(*nb) + nb->len) { 120 fprintf(stderr, "NByte payload size mismatch\n"); 121 return -1; 122 } 123 124 needle = data + sizeof(*nb); 125 126 for (i = 0; i < nb->len; i++) 127 fprintf(fd, "%02x ", needle[i]); 128 129 fprintf(fd, "\""); 130 for (i = 0; i < nb->len; i++) 131 fprintf(fd, "%c", isprint(needle[i]) ? needle[i] : '.'); 132 fprintf(fd, "\" at %d layer %d", nb->off, nb->layer); 133 134 return 0; 135 } 136 137 struct ematch_util nbyte_ematch_util = { 138 .kind = "nbyte", 139 .kind_num = TCF_EM_NBYTE, 140 .parse_eopt = nbyte_parse_eopt, 141 .print_eopt = nbyte_print_eopt, 142 .print_usage = nbyte_print_usage 143 }; 144
