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311b4145 SH |
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> | |
311b4145 SH |
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" \ | |
bc45ded4 | 34 | " LAYER := { link | network | transport | 0..%d }\n" \ |
311b4145 SH |
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"); | |
ae665a52 | 94 | |
311b4145 SH |
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); | |
ae665a52 | 133 | |
311b4145 SH |
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 | }; |