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in-addr-util: introduce in{4,6}_addr_prefix_intersect()

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This commit is contained in:
Yu Watanabe
2024-04-24 12:22:05 +09:00
parent 9dc2503539
commit 21ae0b4b3c
2 changed files with 67 additions and 41 deletions
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src/basic/in-addr-util.c
+51 -40
View File
@@ -194,6 +194,52 @@ int in_addr_equal(int family, const union in_addr_union *a, const union in_addr_
return -EAFNOSUPPORT;
}
bool in4_addr_prefix_intersect(
const struct in_addr *a,
unsigned aprefixlen,
const struct in_addr *b,
unsigned bprefixlen) {
assert(a);
assert(b);
unsigned m = MIN3(aprefixlen, bprefixlen, (unsigned) (sizeof(struct in_addr) * 8));
if (m == 0)
return true; /* Let's return earlier, to avoid shift by 32. */
uint32_t x = be32toh(a->s_addr ^ b->s_addr);
uint32_t n = 0xFFFFFFFFUL << (32 - m);
return (x & n) == 0;
}
bool in6_addr_prefix_intersect(
const struct in6_addr *a,
unsigned aprefixlen,
const struct in6_addr *b,
unsigned bprefixlen) {
assert(a);
assert(b);
unsigned m = MIN3(aprefixlen, bprefixlen, (unsigned) (sizeof(struct in6_addr) * 8));
if (m == 0)
return true;
for (size_t i = 0; i < sizeof(struct in6_addr); i++) {
uint8_t x = a->s6_addr[i] ^ b->s6_addr[i];
uint8_t n = m < 8 ? (0xFF << (8 - m)) : 0xFF;
if ((x & n) != 0)
return false;
if (m <= 8)
break;
m -= 8;
}
return true;
}
int in_addr_prefix_intersect(
int family,
const union in_addr_union *a,
@@ -201,51 +247,16 @@ int in_addr_prefix_intersect(
const union in_addr_union *b,
unsigned bprefixlen) {
unsigned m;
assert(a);
assert(b);
/* Checks whether there are any addresses that are in both networks */
/* Checks whether there are any addresses that are in both networks. */
m = MIN(aprefixlen, bprefixlen);
if (family == AF_INET)
return in4_addr_prefix_intersect(&a->in, aprefixlen, &b->in, bprefixlen);
if (family == AF_INET) {
uint32_t x, nm;
x = be32toh(a->in.s_addr ^ b->in.s_addr);
nm = m == 0 ? 0 : 0xFFFFFFFFUL << (32 - m);
return (x & nm) == 0;
}
if (family == AF_INET6) {
unsigned i;
if (m > 128)
m = 128;
for (i = 0; i < 16; i++) {
uint8_t x, nm;
x = a->in6.s6_addr[i] ^ b->in6.s6_addr[i];
if (m < 8)
nm = 0xFF << (8 - m);
else
nm = 0xFF;
if ((x & nm) != 0)
return 0;
if (m > 8)
m -= 8;
else
m = 0;
}
return 1;
}
if (family == AF_INET6)
return in6_addr_prefix_intersect(&a->in6, aprefixlen, &b->in6, bprefixlen);
return -EAFNOSUPPORT;
}
src/basic/in-addr-util.h
+16 -1
View File
@@ -61,7 +61,22 @@ bool in6_addr_is_ipv4_mapped_address(const struct in6_addr *a);
bool in4_addr_equal(const struct in_addr *a, const struct in_addr *b);
bool in6_addr_equal(const struct in6_addr *a, const struct in6_addr *b);
int in_addr_equal(int family, const union in_addr_union *a, const union in_addr_union *b);
int in_addr_prefix_intersect(int family, const union in_addr_union *a, unsigned aprefixlen, const union in_addr_union *b, unsigned bprefixlen);
bool in4_addr_prefix_intersect(
const struct in_addr *a,
unsigned aprefixlen,
const struct in_addr *b,
unsigned bprefixlen);
bool in6_addr_prefix_intersect(
const struct in6_addr *a,
unsigned aprefixlen,
const struct in6_addr *b,
unsigned bprefixlen);
int in_addr_prefix_intersect(
int family,
const union in_addr_union *a,
unsigned aprefixlen,
const union in_addr_union *b,
unsigned bprefixlen);
int in_addr_prefix_next(int family, union in_addr_union *u, unsigned prefixlen);
int in_addr_prefix_nth(int family, union in_addr_union *u, unsigned prefixlen, uint64_t nth);
int in_addr_random_prefix(int family, union in_addr_union *u, unsigned prefixlen_fixed_part, unsigned prefixlen);