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ip2net : precompute ipv6 masks

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bol-van
2021-09-18 21:22:29 +03:00
parent 9402cd2cf0
commit 0b8072840b
9 changed files with 19 additions and 9 deletions
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28
ip2net/ip2net.c
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@@ -79,7 +79,7 @@ static uint32_t unique6(struct in6_addr *pu, uint32_t ct)
}
return i;
}
static void mask_from_bitcount6(uint32_t zct, struct in6_addr *a)
static void mask_from_bitcount6_make(uint32_t zct, struct in6_addr *a)
{
if (zct >= 128)
memset(a->s6_addr,0x00,16);
@@ -91,6 +91,17 @@ static void mask_from_bitcount6(uint32_t zct, struct in6_addr *a)
a->s6_addr[n] = ~((1 << (zct & 7)) - 1);
}
}
static struct in6_addr ip6_mask[129];
static void mask_from_bitcount6_prepare()
{
for (int zct=0;zct<=128;zct++) mask_from_bitcount6_make(zct, ip6_mask+zct);
}
static inline const struct in6_addr *mask_from_bitcount6(uint32_t zct)
{
return ip6_mask+zct;
}
// result = a & b
static void ip6_and(const struct in6_addr *a, const struct in6_addr *b, struct in6_addr *result)
{
@@ -264,6 +275,7 @@ int main(int argc, char **argv)
}
gnu_quicksort(iplist, ipct, sizeof(*iplist), cmp6, NULL);
ipct = unique6(iplist, ipct);
mask_from_bitcount6_prepare();
/*
for(uint32_t i=0;i<ipct;i++)
@@ -273,18 +285,19 @@ int main(int argc, char **argv)
*/
while (pos < ipct)
{
struct in6_addr mask, ip_start, ip;
const struct in6_addr *mask;
struct in6_addr ip_start, ip;
uint32_t ip_ct_best = 0, zct_best = 0;
pos_end = pos + 1;
// find smallest network with maximum ip coverage with no less than ip6_subnet_threshold addresses
for (zct = params.zct_max; zct >= params.zct_min; zct--)
{
mask_from_bitcount6(zct, &mask);
ip6_and(iplist + pos, &mask, &ip_start);
mask = mask_from_bitcount6(zct);
ip6_and(iplist + pos, mask, &ip_start);
for (p = pos + 1, ip_ct = 1; p < ipct; p++, ip_ct++)
{
ip6_and(iplist + p, &mask, &ip);
ip6_and(iplist + p, mask, &ip);
if (memcmp(&ip_start, &ip, sizeof(ip)))
break;
}
@@ -303,11 +316,8 @@ int main(int argc, char **argv)
}
}
if (zct_best)
{
// network was found
mask_from_bitcount6(zct_best, &mask);
ip6_and(iplist + pos, &mask, &ip_start);
}
ip6_and(iplist + pos, mask_from_bitcount6(zct_best), &ip_start);
else
ip_start = iplist[pos], pos_end = pos + 1; // network not found, use single ip
inet_ntop(AF_INET6, &ip_start, str, sizeof(str));