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lib: make masklen2ip() safer and faster

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This commit is contained in:
Denis Ovsienko 2011-10-08 18:15:21 +04:00
parent 5031ed1347
commit 9663386f16
2 changed files with 40 additions and 17 deletions
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55
lib/prefix.c
View File

@ -31,6 +31,42 @@
/* Maskbit. */ /* Maskbit. */
static const u_char maskbit[] = {0x00, 0x80, 0xc0, 0xe0, 0xf0, static const u_char maskbit[] = {0x00, 0x80, 0xc0, 0xe0, 0xf0,
0xf8, 0xfc, 0xfe, 0xff}; 0xf8, 0xfc, 0xfe, 0xff};
static const u_int32_t maskbytes[] =
{
0x00000000, /* /0 0.0.0.0 */
0x80000000, /* /1 128.0.0.0 */
0xc0000000, /* /2 192.0.0.0 */
0xe0000000, /* /3 224.0.0.0 */
0xf0000000, /* /4 240.0.0.0 */
0xf8000000, /* /5 248.0.0.0 */
0xfc000000, /* /6 252.0.0.0 */
0xfe000000, /* /7 254.0.0.0 */
0xff000000, /* /8 255.0.0.0 */
0xff800000, /* /9 255.128.0.0 */
0xffc00000, /* /10 255.192.0.0 */
0xffe00000, /* /11 255.224.0.0 */
0xfff00000, /* /12 255.240.0.0 */
0xfff80000, /* /13 255.248.0.0 */
0xfffc0000, /* /14 255.252.0.0 */
0xfffe0000, /* /15 255.254.0.0 */
0xffff0000, /* /16 255.255.0.0 */
0xffff8000, /* /17 255.255.128.0 */
0xffffc000, /* /18 255.255.192.0 */
0xffffe000, /* /19 255.255.224.0 */
0xfffff000, /* /20 255.255.240.0 */
0xfffff800, /* /21 255.255.248.0 */
0xfffffc00, /* /22 255.255.252.0 */
0xfffffe00, /* /23 255.255.254.0 */
0xffffff00, /* /24 255.255.255.0 */
0xffffff80, /* /25 255.255.255.128 */
0xffffffc0, /* /26 255.255.255.192 */
0xffffffe0, /* /27 255.255.255.224 */
0xfffffff0, /* /28 255.255.255.240 */
0xfffffff8, /* /29 255.255.255.248 */
0xfffffffc, /* /30 255.255.255.252 */
0xfffffffe, /* /31 255.255.255.254 */
0xffffffff /* /32 255.255.255.255 */
};
/* Number of bits in prefix type. */ /* Number of bits in prefix type. */
#ifndef PNBBY #ifndef PNBBY
@ -303,23 +339,10 @@ str2prefix_ipv4 (const char *str, struct prefix_ipv4 *p)
/* Convert masklen into IP address's netmask. */ /* Convert masklen into IP address's netmask. */
void void
masklen2ip (int masklen, struct in_addr *netmask) masklen2ip (const int masklen, struct in_addr *netmask)
{ {
u_char *pnt; assert (masklen >= 0 && masklen <= 32);
int bit; netmask->s_addr = maskbytes[masklen];
int offset;
memset (netmask, 0, sizeof (struct in_addr));
pnt = (unsigned char *) netmask;
offset = masklen / 8;
bit = masklen % 8;
while (offset--)
*pnt++ = 0xff;
if (bit)
*pnt = maskbit[bit];
} }
/* Convert IP address's netmask into integer. We assume netmask is /* Convert IP address's netmask into integer. We assume netmask is

2
lib/prefix.h
View File

@ -178,7 +178,7 @@ extern int prefix_ipv4_any (const struct prefix_ipv4 *);
extern void apply_classful_mask_ipv4 (struct prefix_ipv4 *); extern void apply_classful_mask_ipv4 (struct prefix_ipv4 *);
extern u_char ip_masklen (struct in_addr); extern u_char ip_masklen (struct in_addr);
extern void masklen2ip (int, struct in_addr *); extern void masklen2ip (const int, struct in_addr *);
/* returns the network portion of the host address */ /* returns the network portion of the host address */
extern in_addr_t ipv4_network_addr (in_addr_t hostaddr, int masklen); extern in_addr_t ipv4_network_addr (in_addr_t hostaddr, int masklen);
/* given the address of a host on a network and the network mask length, /* given the address of a host on a network and the network mask length,