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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 	memset(&cmp, 0, sizeof(cmp));
50 
51 #define PARSE_ERR(CARG, FMT, ARGS...) \
52 	em_parse_error(EINVAL, args, CARG, &cmp_ematch_util, FMT ,##ARGS)
53 
54 	if (args == NULL)
55 		return PARSE_ERR(args, "cmp: missing arguments");
56 
57 	if (!bstrcmp(args, "u8"))
58 		align = TCF_EM_ALIGN_U8;
59 	else if (!bstrcmp(args, "u16"))
60 		align = TCF_EM_ALIGN_U16;
61 	else if (!bstrcmp(args, "u32"))
62 		align = TCF_EM_ALIGN_U32;
63 	else
64 		return PARSE_ERR(args, "cmp: invalid alignment");
65 
66 	for (a = bstr_next(args); a; a = bstr_next(a)) {
67 		if (!bstrcmp(a, "at")) {
68 			if (a->next == NULL)
69 				return PARSE_ERR(a, "cmp: missing argument");
70 			a = bstr_next(a);
71 
72 			offset = bstrtoul(a);
73 			if (offset == ULONG_MAX)
74 				return PARSE_ERR(a, "cmp: invalid offset, " \
75 				    "must be numeric");
76 
77 			offset_present = 1;
78 		} else if (!bstrcmp(a, "layer")) {
79 			if (a->next == NULL)
80 				return PARSE_ERR(a, "cmp: missing argument");
81 			a = bstr_next(a);
82 
83 			layer = parse_layer(a);
84 			if (layer == INT_MAX) {
85 				layer = bstrtoul(a);
86 				if (layer == ULONG_MAX)
87 					return PARSE_ERR(a, "cmp: invalid " \
88 					    "layer");
89 			}
90 
91 			if (layer > TCF_LAYER_MAX)
92 				return PARSE_ERR(a, "cmp: illegal layer, " \
93 				    "must be in 0..%d", TCF_LAYER_MAX);
94 		} else if (!bstrcmp(a, "mask")) {
95 			if (a->next == NULL)
96 				return PARSE_ERR(a, "cmp: missing argument");
97 			a = bstr_next(a);
98 
99 			mask = bstrtoul(a);
100 			if (mask == ULONG_MAX)
101 				return PARSE_ERR(a, "cmp: invalid mask");
102 		} else if (!bstrcmp(a, "trans")) {
103 			cmp.flags |= TCF_EM_CMP_TRANS;
104 		} else if (!bstrcmp(a, "eq") || !bstrcmp(a, "gt") ||
105 		    !bstrcmp(a, "lt")) {
106 
107 			if (!bstrcmp(a, "eq"))
108 				opnd = TCF_EM_OPND_EQ;
109 			else if (!bstrcmp(a, "gt"))
110 				opnd = TCF_EM_OPND_GT;
111 			else if (!bstrcmp(a, "lt"))
112 				opnd = TCF_EM_OPND_LT;
113 
114 			if (a->next == NULL)
115 				return PARSE_ERR(a, "cmp: missing argument");
116 			a = bstr_next(a);
117 
118 			value = bstrtoul(a);
119 			if (value == ULONG_MAX)
120 				return PARSE_ERR(a, "cmp: invalid value");
121 
122 			value_present = 1;
123 		} else
124 			return PARSE_ERR(a, "nbyte: unknown parameter");
125 	}
126 
127 	if (offset_present == 0 || value_present == 0)
128 		return PARSE_ERR(a, "cmp: offset and value required");
129 
130 	cmp.val = (__u32) value;
131 	cmp.mask = (__u32) mask;
132 	cmp.off = (__u16) offset;
133 	cmp.align = (__u8) align;
134 	cmp.layer = (__u8) layer;
135 	cmp.opnd = (__u8) opnd;
136 
137 	addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));
138 	addraw_l(n, MAX_MSG, &cmp, sizeof(cmp));
139 
140 #undef PARSE_ERR
141 	return 0;
142 }
143 
cmp_print_eopt(FILE * fd,struct tcf_ematch_hdr * hdr,void * data,int data_len)144 static int cmp_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,
145 			  int data_len)
146 {
147 	struct tcf_em_cmp *cmp = data;
148 
149 	if (data_len < sizeof(*cmp)) {
150 		fprintf(stderr, "CMP header size mismatch\n");
151 		return -1;
152 	}
153 
154 	if (cmp->align == TCF_EM_ALIGN_U8)
155 		fprintf(fd, "u8 ");
156 	else if (cmp->align == TCF_EM_ALIGN_U16)
157 		fprintf(fd, "u16 ");
158 	else if (cmp->align == TCF_EM_ALIGN_U32)
159 		fprintf(fd, "u32 ");
160 
161 	fprintf(fd, "at %d layer %d ", cmp->off, cmp->layer);
162 
163 	if (cmp->mask)
164 		fprintf(fd, "mask 0x%x ", cmp->mask);
165 
166 	if (cmp->flags & TCF_EM_CMP_TRANS)
167 		fprintf(fd, "trans ");
168 
169 	if (cmp->opnd == TCF_EM_OPND_EQ)
170 		fprintf(fd, "eq ");
171 	else if (cmp->opnd == TCF_EM_OPND_LT)
172 		fprintf(fd, "lt ");
173 	else if (cmp->opnd == TCF_EM_OPND_GT)
174 		fprintf(fd, "gt ");
175 
176 	fprintf(fd, "%d", cmp->val);
177 
178 	return 0;
179 }
180 
181 struct ematch_util cmp_ematch_util = {
182 	.kind = "cmp",
183 	.kind_num = TCF_EM_CMP,
184 	.parse_eopt = cmp_parse_eopt,
185 	.print_eopt = cmp_print_eopt,
186 	.print_usage = cmp_print_usage
187 };
188