1 /*
2 * em_cmp.c Simple comparison 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 <errno.h>
22
23 #include "m_ematch.h"
24 #include <linux/tc_ematch/tc_em_cmp.h>
25
26 extern struct ematch_util cmp_ematch_util;
27
cmp_print_usage(FILE * fd)28 static void cmp_print_usage(FILE *fd)
29 {
30 fprintf(fd,
31 "Usage: cmp(ALIGN at OFFSET [ ATTRS ] { eq | lt | gt } VALUE)\n" \
32 "where: ALIGN := { u8 | u16 | u32 }\n" \
33 " ATTRS := [ layer LAYER ] [ mask MASK ] [ trans ]\n" \
34 " LAYER := { link | network | transport | 0..%d }\n" \
35 "\n" \
36 "Example: cmp(u16 at 3 layer 2 mask 0xff00 gt 20)\n",
37 TCF_LAYER_MAX);
38 }
39
cmp_parse_eopt(struct nlmsghdr * n,struct tcf_ematch_hdr * hdr,struct bstr * args)40 static int cmp_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr,
41 struct bstr *args)
42 {
43 struct bstr *a;
44 int align, opnd = 0;
45 unsigned long offset = 0, layer = TCF_LAYER_NETWORK, mask = 0, value = 0;
46 int offset_present = 0, value_present = 0;
47 struct tcf_em_cmp cmp = {};
48
49 #define PARSE_ERR(CARG, FMT, ARGS...) \
50 em_parse_error(EINVAL, args, CARG, &cmp_ematch_util, FMT, ##ARGS)
51
52 if (args == NULL)
53 return PARSE_ERR(args, "cmp: missing arguments");
54
55 if (!bstrcmp(args, "u8"))
56 align = TCF_EM_ALIGN_U8;
57 else if (!bstrcmp(args, "u16"))
58 align = TCF_EM_ALIGN_U16;
59 else if (!bstrcmp(args, "u32"))
60 align = TCF_EM_ALIGN_U32;
61 else
62 return PARSE_ERR(args, "cmp: invalid alignment");
63
64 for (a = bstr_next(args); a; a = bstr_next(a)) {
65 if (!bstrcmp(a, "at")) {
66 if (a->next == NULL)
67 return PARSE_ERR(a, "cmp: missing argument");
68 a = bstr_next(a);
69
70 offset = bstrtoul(a);
71 if (offset == ULONG_MAX)
72 return PARSE_ERR(a, "cmp: invalid offset, " \
73 "must be numeric");
74
75 offset_present = 1;
76 } else if (!bstrcmp(a, "layer")) {
77 if (a->next == NULL)
78 return PARSE_ERR(a, "cmp: missing argument");
79 a = bstr_next(a);
80
81 layer = parse_layer(a);
82 if (layer == INT_MAX) {
83 layer = bstrtoul(a);
84 if (layer == ULONG_MAX)
85 return PARSE_ERR(a, "cmp: invalid " \
86 "layer");
87 }
88
89 if (layer > TCF_LAYER_MAX)
90 return PARSE_ERR(a, "cmp: illegal layer, " \
91 "must be in 0..%d", TCF_LAYER_MAX);
92 } else if (!bstrcmp(a, "mask")) {
93 if (a->next == NULL)
94 return PARSE_ERR(a, "cmp: missing argument");
95 a = bstr_next(a);
96
97 mask = bstrtoul(a);
98 if (mask == ULONG_MAX)
99 return PARSE_ERR(a, "cmp: invalid mask");
100 } else if (!bstrcmp(a, "trans")) {
101 cmp.flags |= TCF_EM_CMP_TRANS;
102 } else if (!bstrcmp(a, "eq") || !bstrcmp(a, "gt") ||
103 !bstrcmp(a, "lt")) {
104
105 if (!bstrcmp(a, "eq"))
106 opnd = TCF_EM_OPND_EQ;
107 else if (!bstrcmp(a, "gt"))
108 opnd = TCF_EM_OPND_GT;
109 else if (!bstrcmp(a, "lt"))
110 opnd = TCF_EM_OPND_LT;
111
112 if (a->next == NULL)
113 return PARSE_ERR(a, "cmp: missing argument");
114 a = bstr_next(a);
115
116 value = bstrtoul(a);
117 if (value == ULONG_MAX)
118 return PARSE_ERR(a, "cmp: invalid value");
119
120 value_present = 1;
121 } else
122 return PARSE_ERR(a, "nbyte: unknown parameter");
123 }
124
125 if (offset_present == 0 || value_present == 0)
126 return PARSE_ERR(a, "cmp: offset and value required");
127
128 cmp.val = (__u32) value;
129 cmp.mask = (__u32) mask;
130 cmp.off = (__u16) offset;
131 cmp.align = (__u8) align;
132 cmp.layer = (__u8) layer;
133 cmp.opnd = (__u8) opnd;
134
135 addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));
136 addraw_l(n, MAX_MSG, &cmp, sizeof(cmp));
137
138 #undef PARSE_ERR
139 return 0;
140 }
141
cmp_print_eopt(FILE * fd,struct tcf_ematch_hdr * hdr,void * data,int data_len)142 static int cmp_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,
143 int data_len)
144 {
145 struct tcf_em_cmp *cmp = data;
146
147 if (data_len < sizeof(*cmp)) {
148 fprintf(stderr, "CMP header size mismatch\n");
149 return -1;
150 }
151
152 if (cmp->align == TCF_EM_ALIGN_U8)
153 fprintf(fd, "u8 ");
154 else if (cmp->align == TCF_EM_ALIGN_U16)
155 fprintf(fd, "u16 ");
156 else if (cmp->align == TCF_EM_ALIGN_U32)
157 fprintf(fd, "u32 ");
158
159 fprintf(fd, "at %d layer %d ", cmp->off, cmp->layer);
160
161 if (cmp->mask)
162 fprintf(fd, "mask 0x%x ", cmp->mask);
163
164 if (cmp->flags & TCF_EM_CMP_TRANS)
165 fprintf(fd, "trans ");
166
167 if (cmp->opnd == TCF_EM_OPND_EQ)
168 fprintf(fd, "eq ");
169 else if (cmp->opnd == TCF_EM_OPND_LT)
170 fprintf(fd, "lt ");
171 else if (cmp->opnd == TCF_EM_OPND_GT)
172 fprintf(fd, "gt ");
173
174 fprintf(fd, "%d", cmp->val);
175
176 return 0;
177 }
178
179 struct ematch_util cmp_ematch_util = {
180 .kind = "cmp",
181 .kind_num = TCF_EM_CMP,
182 .parse_eopt = cmp_parse_eopt,
183 .print_eopt = cmp_print_eopt,
184 .print_usage = cmp_print_usage
185 };
186