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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> | |
311b4145 SH |
15 | #include <fcntl.h> |
16 | #include <sys/socket.h> | |
17 | #include <netinet/in.h> | |
18 | #include <arpa/inet.h> | |
19 | #include <string.h> | |
311b4145 SH |
20 | #include <errno.h> |
21 | ||
22 | #include "m_ematch.h" | |
23 | #include <linux/tc_ematch/tc_em_nbyte.h> | |
24 | ||
25 | extern struct ematch_util nbyte_ematch_util; | |
26 | ||
27 | static void nbyte_print_usage(FILE *fd) | |
28 | { | |
29 | fprintf(fd, | |
30 | "Usage: nbyte(NEEDLE at OFFSET [layer LAYER])\n" \ | |
31 | "where: NEEDLE := { string | \"c-escape-sequence\" }\n" \ | |
32 | " OFFSET := int\n" \ | |
bc45ded4 | 33 | " LAYER := { link | network | transport | 0..%d }\n" \ |
311b4145 SH |
34 | "\n" \ |
35 | "Example: nbyte(\"ababa\" at 12 layer 1)\n", | |
36 | TCF_LAYER_MAX); | |
37 | } | |
38 | ||
39 | static int nbyte_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr, | |
40 | struct bstr *args) | |
41 | { | |
42 | struct bstr *a; | |
43 | struct bstr *needle = args; | |
44 | unsigned long offset = 0, layer = TCF_LAYER_NETWORK; | |
45 | int offset_present = 0; | |
d17b136f | 46 | struct tcf_em_nbyte nb = {}; |
311b4145 SH |
47 | |
48 | #define PARSE_ERR(CARG, FMT, ARGS...) \ | |
32a121cb | 49 | em_parse_error(EINVAL, args, CARG, &nbyte_ematch_util, FMT, ##ARGS) |
311b4145 SH |
50 | |
51 | if (args == NULL) | |
52 | return PARSE_ERR(args, "nbyte: missing arguments"); | |
53 | ||
54 | if (needle->len <= 0) | |
55 | return PARSE_ERR(args, "nbyte: needle length is 0"); | |
56 | ||
57 | for (a = bstr_next(args); a; a = bstr_next(a)) { | |
58 | if (!bstrcmp(a, "at")) { | |
59 | if (a->next == NULL) | |
60 | return PARSE_ERR(a, "nbyte: missing argument"); | |
61 | a = bstr_next(a); | |
62 | ||
63 | offset = bstrtoul(a); | |
64 | if (offset == ULONG_MAX) | |
65 | return PARSE_ERR(a, "nbyte: invalid offset, " \ | |
66 | "must be numeric"); | |
67 | ||
68 | offset_present = 1; | |
69 | } else if (!bstrcmp(a, "layer")) { | |
70 | if (a->next == NULL) | |
71 | return PARSE_ERR(a, "nbyte: missing argument"); | |
72 | a = bstr_next(a); | |
73 | ||
74 | layer = parse_layer(a); | |
75 | if (layer == INT_MAX) { | |
76 | layer = bstrtoul(a); | |
77 | if (layer == ULONG_MAX) | |
78 | return PARSE_ERR(a, "nbyte: invalid " \ | |
79 | "layer"); | |
80 | } | |
81 | ||
82 | if (layer > TCF_LAYER_MAX) | |
83 | return PARSE_ERR(a, "nbyte: illegal layer, " \ | |
84 | "must be in 0..%d", TCF_LAYER_MAX); | |
85 | } else | |
86 | return PARSE_ERR(a, "nbyte: unknown parameter"); | |
87 | } | |
88 | ||
89 | if (offset_present == 0) | |
90 | return PARSE_ERR(a, "nbyte: offset required"); | |
ae665a52 | 91 | |
311b4145 SH |
92 | nb.len = needle->len; |
93 | nb.layer = (__u8) layer; | |
94 | nb.off = (__u16) offset; | |
95 | ||
96 | addraw_l(n, MAX_MSG, hdr, sizeof(*hdr)); | |
97 | addraw_l(n, MAX_MSG, &nb, sizeof(nb)); | |
98 | addraw_l(n, MAX_MSG, needle->data, needle->len); | |
99 | ||
100 | #undef PARSE_ERR | |
101 | return 0; | |
102 | } | |
103 | ||
104 | static int nbyte_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data, | |
105 | int data_len) | |
106 | { | |
107 | int i; | |
108 | struct tcf_em_nbyte *nb = data; | |
109 | __u8 *needle; | |
110 | ||
111 | if (data_len < sizeof(*nb)) { | |
112 | fprintf(stderr, "NByte header size mismatch\n"); | |
113 | return -1; | |
114 | } | |
115 | ||
116 | if (data_len < sizeof(*nb) + nb->len) { | |
117 | fprintf(stderr, "NByte payload size mismatch\n"); | |
118 | return -1; | |
119 | } | |
120 | ||
121 | needle = data + sizeof(*nb); | |
122 | ||
123 | for (i = 0; i < nb->len; i++) | |
124 | fprintf(fd, "%02x ", needle[i]); | |
125 | ||
126 | fprintf(fd, "\""); | |
127 | for (i = 0; i < nb->len; i++) | |
128 | fprintf(fd, "%c", isprint(needle[i]) ? needle[i] : '.'); | |
129 | fprintf(fd, "\" at %d layer %d", nb->off, nb->layer); | |
ae665a52 | 130 | |
311b4145 SH |
131 | return 0; |
132 | } | |
133 | ||
134 | struct ematch_util nbyte_ematch_util = { | |
135 | .kind = "nbyte", | |
136 | .kind_num = TCF_EM_NBYTE, | |
137 | .parse_eopt = nbyte_parse_eopt, | |
138 | .print_eopt = nbyte_print_eopt, | |
139 | .print_usage = nbyte_print_usage | |
140 | }; |