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
26extern struct ematch_util cmp_ematch_util;
27
28static 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
40static 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
144static 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
181struct 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