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-rw-r--r--src/shared/dns-domain.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index 33925bfbd1..8a0dec1540 100644
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -529,6 +529,28 @@ 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;