suricata
util-cidr.c
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1 /* Copyright (C) 2007-2022 Open Information Security Foundation
2  *
3  * You can copy, redistribute or modify this Program under the terms of
4  * the GNU General Public License version 2 as published by the Free
5  * Software Foundation.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * version 2 along with this program; if not, write to the Free Software
14  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
15  * 02110-1301, USA.
16  */
17 
18 /**
19  * \file
20  *
21  * \author Victor Julien <victor@inliniac.net>
22  *
23  * CIDR utility functions
24  */
25 
26 #include "suricata-common.h"
27 #include "util-cidr.h"
28 #include "util-debug.h"
29 #include "util-unittest.h"
30 
31 /** \brief Turn 32 bit mask into CIDR
32  *
33  * \retval cidr The cidr value or -1 if the netmask can't be expressed as cidr
34  */
35 int CIDRFromMask(uint32_t netmask)
36 {
37  netmask = ntohl(netmask);
38  if (netmask == 0) {
39  return 0;
40  }
41  int p = 0;
42  bool seen_1 = false;
43  while (netmask > 0) {
44  if (netmask & 1) {
45  seen_1 = true;
46  p++;
47  } else {
48  if (seen_1) {
49  return -1;
50  }
51  }
52  netmask >>= 1;
53  }
54  return p;
55 }
56 
57 uint32_t CIDRGet(int cidr)
58 {
59  if (cidr <= 0 || cidr > 32)
60  return 0;
61  uint32_t netmask = htonl(0xFFFFFFFF << (32UL - (uint32_t)cidr));
62  SCLogDebug("CIDR %d -> netmask %08X", cidr, netmask);
63  return netmask;
64 }
65 
66 /**
67  * \brief Creates a cidr ipv6 netblock, based on the cidr netblock value.
68  *
69  * For example if we send a cidr of 7 as argument, an ipv6 address
70  * mask of the value FE:00:00:00:00:00:00:00 is created and updated
71  * in the argument struct in6_addr *in6.
72  *
73  * \todo I think for the final section: while (cidr > 0), we can simply
74  * replace it with a
75  * if (cidr > 0) {
76  * in6->s6_addr[i] = -1 << (8 - cidr);
77  *
78  * \param cidr The value of the cidr.
79  * \param in6 Pointer to an ipv6 address structure(struct in6_addr) which will
80  * hold the cidr netblock result.
81  */
82 void CIDRGetIPv6(int cidr, struct in6_addr *in6)
83 {
84  int i = 0;
85 
86  memset(in6, 0, sizeof(struct in6_addr));
87 
88  while (cidr > 8) {
89  in6->s6_addr[i] = 0xff;
90  cidr -= 8;
91  i++;
92  }
93 
94  while (cidr > 0) {
95  in6->s6_addr[i] |= 0x80;
96  if (--cidr > 0)
97  in6->s6_addr[i] = in6->s6_addr[i] >> 1;
98  }
99 }
100 
101 #ifdef UNITTESTS
102 
103 static int CIDRFromMaskTest01(void)
104 {
105  struct in_addr in;
106  int v = inet_pton(AF_INET, "255.255.255.0", &in);
107 
108  FAIL_IF(v <= 0);
109  FAIL_IF_NOT(24 == CIDRFromMask(in.s_addr));
110 
111  PASS;
112 }
113 
114 static int CIDRFromMaskTest02(void)
115 {
116  struct in_addr in;
117  int v = inet_pton(AF_INET, "255.255.0.42", &in);
118 
119  FAIL_IF(v <= 0);
120  FAIL_IF_NOT(-1 == CIDRFromMask(in.s_addr));
121 
122  PASS;
123 }
124 
125 static int CIDRFromMaskTest03(void)
126 {
127  struct in_addr in;
128  int v = inet_pton(AF_INET, "0.0.0.0", &in);
129 
130  FAIL_IF(v <= 0);
131  FAIL_IF_NOT(0 == CIDRFromMask(in.s_addr));
132 
133  PASS;
134 }
135 
136 static int CIDRFromMaskTest04(void)
137 {
138  struct in_addr in;
139  int v = inet_pton(AF_INET, "255.255.255.255", &in);
140 
141  FAIL_IF(v <= 0);
142  FAIL_IF_NOT(32 == CIDRFromMask(in.s_addr));
143 
144  PASS;
145 }
146 
147 #endif /* UNITTESTS */
148 
149 void UtilCIDRTests(void)
150 {
151 #ifdef UNITTESTS
152  UtRegisterTest("CIDRFromMaskTest01", CIDRFromMaskTest01);
153  UtRegisterTest("CIDRFromMaskTest02", CIDRFromMaskTest02);
154  UtRegisterTest("CIDRFromMaskTest03", CIDRFromMaskTest03);
155  UtRegisterTest("CIDRFromMaskTest04", CIDRFromMaskTest04);
156 #endif /* UNITTESTS */
157 }
UtRegisterTest
void UtRegisterTest(const char *name, int(*TestFn)(void))
Register unit test.
Definition: util-unittest.c:103
SCLogDebug
#define SCLogDebug(...)
Definition: util-debug.h:275
CIDRGet
uint32_t CIDRGet(int cidr)
Definition: util-cidr.c:57
util-unittest.h
FAIL_IF_NOT
#define FAIL_IF_NOT(expr)
Fail a test if expression evaluates to false.
Definition: util-unittest.h:82
util-cidr.h
util-debug.h
PASS
#define PASS
Pass the test.
Definition: util-unittest.h:105
CIDRFromMask
int CIDRFromMask(uint32_t netmask)
Turn 32 bit mask into CIDR.
Definition: util-cidr.c:35
UtilCIDRTests
void UtilCIDRTests(void)
Definition: util-cidr.c:149
CIDRGetIPv6
void CIDRGetIPv6(int cidr, struct in6_addr *in6)
Creates a cidr ipv6 netblock, based on the cidr netblock value.
Definition: util-cidr.c:82
FAIL_IF
#define FAIL_IF(expr)
Fail a test if expression evaluates to true.
Definition: util-unittest.h:71
suricata-common.h