1 files changed, 85 insertions, 0 deletions
diff --git a/src/lib-dns/dns-util.c b/src/lib-dns/dns-util.c
new file mode 100644
index 0000000..a8469ce
--- /dev/null
+++ b/src/lib-dns/dns-util.c
@@ -0,0 +1,85 @@
+/* Copyright (c) 2010-2018 Dovecot authors, see the included COPYING file */
+#include "lib.h"
+#include "dns-util.h"
+
+/**
+  return first position from b->a of c or a if not found
+ */
+static inline
+const char *strchr_ba(const char *a, const char *b, char c)
+{
+	for(;b>a && *b != c; b--);
+	return b;
+}
+
+int dns_ncompare(const char *a, const char *b, size_t n)
+{
+	if (a == NULL && b == NULL) return 0;
+	if (a == NULL && b != NULL) return 1;
+	if (a != NULL && b == NULL) return -1;
+
+	for(size_t i = 0; i < n &&
+			  *a != '\0' &&
+			  *b != '\0' &&
+			  dns_tolower(*a) == dns_tolower(*b);
+	    i++, a++, b++);
+
+	return dns_tolower(*a) - dns_tolower(*b);
+}
+
+int dns_compare(const char *a, const char *b)
+{
+	return dns_ncompare(a, b, SIZE_MAX);
+}
+
+int dns_compare_labels(const char *a, const char *b)
+{
+	if (a == NULL && b == NULL) return 0;
+	if (a == NULL && b != NULL) return 1;
+	if (a != NULL && b == NULL) return -1;
+
+	const char *ptr_a = a + strlen(a);
+	const char *ptr_b = b + strlen(b);
+	const char *label_a = ptr_a, *label_b = ptr_b;
+	int comp = 0;
+
+	while(comp == 0 && ptr_a > a && ptr_b > b) {
+		/* look for start of label, including dot */
+		label_a = strchr_ba(a, ptr_a, '.');
+		label_b = strchr_ba(b, ptr_b, '.');
+		if (ptr_a - label_a != ptr_b - label_b)
+			/* compare labels up to minimum length
+			   but include \0 to make sure that we
+			   don't consider alpha and alphabet
+			   equal */
+			return dns_ncompare(label_a, label_b,
+					   I_MIN(ptr_a - label_a,
+						 ptr_b - label_b)+1);
+		comp = dns_ncompare(label_a, label_b, ptr_a -label_a);
+		ptr_a = label_a - 1;
+		ptr_b = label_b - 1;
+	}
+
+	return dns_tolower(*label_a) - dns_tolower(*label_b);
+}
+
+int dns_match_wildcard(const char *name, const char *mask)
+{
+	i_assert(name != NULL && mask != NULL);
+
+	for(;*name != '\0' && *mask != '\0'; name++, mask++) {
+		switch(*mask) {
+		case '*':
+			name = strchr(name, '.');
+			if (name == NULL || mask[1] != '.') return -1;
+			mask++;
+			break;
+		case '?':
+			break;
+		default:
+			if (dns_tolower(*name) != dns_tolower(*mask)) return -1;
+		}
+	}
+	if (*mask == '*') mask++;
+	return dns_tolower(*name) == dns_tolower(*mask) ? 0 : -1;
+}