1 files changed, 113 insertions, 0 deletions
diff --git a/lib/dns/ecs.c b/lib/dns/ecs.c
new file mode 100644
index 0000000..676c740
--- /dev/null
+++ b/lib/dns/ecs.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*! \file */
+
+#include <string.h>
+
+#include <isc/buffer.h>
+#include <isc/mem.h>
+#include <isc/netaddr.h>
+#include <isc/print.h>
+#include <isc/util.h>
+
+#include <dns/ecs.h>
+#include <dns/nsec.h>
+#include <dns/rbt.h>
+#include <dns/rdata.h>
+#include <dns/rdatatype.h>
+#include <dns/result.h>
+#include <dns/types.h>
+
+void
+dns_ecs_init(dns_ecs_t *ecs) {
+	isc_netaddr_unspec(&ecs->addr);
+	ecs->source = 0;
+	ecs->scope = 0xff;
+}
+
+bool
+dns_ecs_equals(const dns_ecs_t *ecs1, const dns_ecs_t *ecs2) {
+	const unsigned char *addr1, *addr2;
+	uint8_t mask;
+	size_t alen;
+
+	REQUIRE(ecs1 != NULL && ecs2 != NULL);
+
+	if (ecs1->source != ecs2->source ||
+	    ecs1->addr.family != ecs2->addr.family)
+	{
+		return (false);
+	}
+
+	alen = (ecs1->source + 7) / 8;
+	if (alen == 0) {
+		return (true);
+	}
+
+	switch (ecs1->addr.family) {
+	case AF_INET:
+		INSIST(alen <= 4);
+		addr1 = (const unsigned char *)&ecs1->addr.type.in;
+		addr2 = (const unsigned char *)&ecs2->addr.type.in;
+		break;
+	case AF_INET6:
+		INSIST(alen <= 16);
+		addr1 = (const unsigned char *)&ecs1->addr.type.in6;
+		addr2 = (const unsigned char *)&ecs2->addr.type.in6;
+		break;
+	default:
+		UNREACHABLE();
+	}
+
+	/*
+	 * Compare all octets except the final octet of the address
+	 * prefix.
+	 */
+	if (alen > 1 && memcmp(addr1, addr2, alen - 1) != 0) {
+		return (false);
+	}
+
+	/*
+	 * It should not be necessary to mask the final octet; all
+	 * bits past the source prefix length are supposed to be 0.
+	 * However, it seems prudent not to omit them from the
+	 * comparison anyway.
+	 */
+	mask = (~0U << (8 - (ecs1->source % 8))) & 0xff;
+	if (mask == 0) {
+		mask = 0xff;
+	}
+
+	if ((addr1[alen - 1] & mask) != (addr2[alen - 1] & mask)) {
+		return (false);
+	}
+
+	return (true);
+}
+
+void
+dns_ecs_format(const dns_ecs_t *ecs, char *buf, size_t size) {
+	size_t len;
+	char *p;
+
+	REQUIRE(ecs != NULL);
+	REQUIRE(buf != NULL);
+	REQUIRE(size >= DNS_ECS_FORMATSIZE);
+
+	isc_netaddr_format(&ecs->addr, buf, size);
+	len = strlen(buf);
+	p = buf + len;
+	snprintf(p, size - len, "/%d/%d", ecs->source,
+		 ecs->scope == 0xff ? 0 : ecs->scope);
+}