diff options
Diffstat (limited to 'src/shared/dns-domain.c')
| -rw-r--r-- | src/shared/dns-domain.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c index 20a44ce4e..e716d333e 100644 --- a/src/shared/dns-domain.c +++ b/src/shared/dns-domain.c @@ -464,6 +464,28 @@ int dns_name_endswith(const char *name, const char *suffix) { } } +int dns_name_between(const char *a, const char *b, const char *c) { + int n; + + /* Determine if b is strictly greater than a and strictly smaller than c. + We consider the order of names to be circular, so that if a is + strictly greater than c, we consider b to be between them if it is + either greater than a or smaller than c. This is how the canonical + DNS name order used in NSEC records work. */ + + n = dns_name_compare_func(a, c); + if (n == 0) + return -EINVAL; + else if (n < 0) + /* a<---b--->c */ + return dns_name_compare_func(a, b) < 0 && + dns_name_compare_func(b, c) < 0; + else + /* <--b--c a--b--> */ + return dns_name_compare_func(b, c) < 0 || + dns_name_compare_func(a, b) < 0; +} + int dns_name_reverse(int family, const union in_addr_union *a, char **ret) { const uint8_t *p; int r; |