1/*
2 * em_u32.c		U32 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
25extern struct ematch_util u32_ematch_util;
26
27static void u32_print_usage(FILE *fd)
28{
29	fprintf(fd,
30	    "Usage: u32(ALIGN VALUE MASK at [ nexthdr+ ] OFFSET)\n" \
31	    "where: ALIGN  := { u8 | u16 | u32 }\n" \
32	    "\n" \
33	    "Example: u32(u16 0x1122 0xffff at nexthdr+4)\n");
34}
35
36static int u32_parse_eopt(struct nlmsghdr *n, struct tcf_ematch_hdr *hdr,
37			  struct bstr *args)
38{
39	struct bstr *a;
40	int align, nh_len;
41	unsigned long key, mask, offmask = 0, offset;
42	struct tc_u32_key u_key;
43
44	memset(&u_key, 0, sizeof(u_key));
45
46#define PARSE_ERR(CARG, FMT, ARGS...) \
47	em_parse_error(EINVAL, args, CARG, &u32_ematch_util, FMT ,##ARGS)
48
49	if (args == NULL)
50		return PARSE_ERR(args, "u32: missing arguments");
51
52	if (!bstrcmp(args, "u8"))
53		align = 1;
54	else if (!bstrcmp(args, "u16"))
55		align = 2;
56	else if (!bstrcmp(args, "u32"))
57		align = 4;
58	else
59		return PARSE_ERR(args, "u32: invalid alignment");
60
61	a = bstr_next(args);
62	if (a == NULL)
63		return PARSE_ERR(a, "u32: missing key");
64
65	key = bstrtoul(a);
66	if (key == ULONG_MAX)
67		return PARSE_ERR(a, "u32: invalid key, must be numeric");
68
69	a = bstr_next(a);
70	if (a == NULL)
71		return PARSE_ERR(a, "u32: missing mask");
72
73	mask = bstrtoul(a);
74	if (mask == ULONG_MAX)
75		return PARSE_ERR(a, "u32: invalid mask, must be numeric");
76
77	a = bstr_next(a);
78	if (a == NULL || bstrcmp(a, "at") != 0)
79		return PARSE_ERR(a, "u32: missing \"at\"");
80
81	a = bstr_next(a);
82	if (a == NULL)
83		return PARSE_ERR(a, "u32: missing offset");
84
85	nh_len = strlen("nexthdr+");
86	if (a->len > nh_len && !memcmp(a->data, "nexthdr+", nh_len)) {
87		char buf[a->len - nh_len + 1];
88		offmask = -1;
89		memcpy(buf, a->data + nh_len, a->len - nh_len);
90		offset = strtoul(buf, NULL, 0);
91	} else if (!bstrcmp(a, "nexthdr+")) {
92		a = bstr_next(a);
93		if (a == NULL)
94			return PARSE_ERR(a, "u32: missing offset");
95		offset = bstrtoul(a);
96	} else
97		offset = bstrtoul(a);
98
99	if (offset == ULONG_MAX)
100		return PARSE_ERR(a, "u32: invalid offset");
101
102	if (a->next)
103		return PARSE_ERR(a->next, "u32: unexpected trailer");
104
105	switch (align) {
106		case 1:
107			if (key > 0xFF)
108				return PARSE_ERR(a, "Illegal key (>0xFF)");
109			if (mask > 0xFF)
110				return PARSE_ERR(a, "Illegal mask (>0xFF)");
111
112			key <<= 24 - ((offset & 3) * 8);
113			mask <<= 24 - ((offset & 3) * 8);
114			offset &= ~3;
115			break;
116
117		case 2:
118			if (key > 0xFFFF)
119				return PARSE_ERR(a, "Illegal key (>0xFFFF)");
120			if (mask > 0xFFFF)
121				return PARSE_ERR(a, "Illegal mask (>0xFFFF)");
122
123			if ((offset & 3) == 0) {
124				key <<= 16;
125				mask <<= 16;
126			}
127			offset &= ~3;
128			break;
129	}
130
131	key = htonl(key);
132	mask = htonl(mask);
133
134	if (offset % 4)
135		return PARSE_ERR(a, "u32: invalid offset alignment, " \
136		    "must be aligned to 4.");
137
138	key &= mask;
139
140	u_key.mask = mask;
141	u_key.val = key;
142	u_key.off = offset;
143	u_key.offmask = offmask;
144
145	addraw_l(n, MAX_MSG, hdr, sizeof(*hdr));
146	addraw_l(n, MAX_MSG, &u_key, sizeof(u_key));
147
148#undef PARSE_ERR
149	return 0;
150}
151
152static int u32_print_eopt(FILE *fd, struct tcf_ematch_hdr *hdr, void *data,
153			  int data_len)
154{
155	struct tc_u32_key *u_key = data;
156
157	if (data_len < sizeof(*u_key)) {
158		fprintf(stderr, "U32 header size mismatch\n");
159		return -1;
160	}
161
162	fprintf(fd, "%08x/%08x at %s%d",
163	    (unsigned int) ntohl(u_key->val),
164	    (unsigned int) ntohl(u_key->mask),
165	    u_key->offmask ? "nexthdr+" : "",
166	    u_key->off);
167
168	return 0;
169}
170
171struct ematch_util u32_ematch_util = {
172	.kind = "u32",
173	.kind_num = TCF_EM_U32,
174	.parse_eopt = u32_parse_eopt,
175	.print_eopt = u32_print_eopt,
176	.print_usage = u32_print_usage
177};
178