From 90ed76b1cf728b4c24857ebd64a7dcac29ffc7f9 Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Thu, 24 Jun 2021 10:13:11 +1000
Subject: [PATCH] Add dns_zonemd_supported

---
 lib/dns/include/dns/zonemd.h |  3 +++
 lib/dns/zonemd.c             | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/lib/dns/include/dns/zonemd.h b/lib/dns/include/dns/zonemd.h
index 357a23345f..a6061478ac 100644
--- a/lib/dns/include/dns/zonemd.h
+++ b/lib/dns/include/dns/zonemd.h
@@ -22,3 +22,6 @@ dns_zonemd_buildrdata(dns_rdata_t *rdata, dns_db_t *db,
 		      dns_dbversion_t *version, uint8_t scheme,
 		      uint8_t algorithm, isc_mem_t *mctx, unsigned char *buf,
 		      size_t size);
+
+bool
+dns_zonemd_supported(dns_rdata_t *rdata);
diff --git a/lib/dns/zonemd.c b/lib/dns/zonemd.c
index a72c3c25d8..80ebe709dd 100644
--- a/lib/dns/zonemd.c
+++ b/lib/dns/zonemd.c
@@ -427,3 +427,23 @@ dns_zonemd_buildrdata(dns_rdata_t *rdata, dns_db_t *db,
 		return ISC_R_NOTIMPLEMENTED;
 	}
 }
+
+bool
+dns_zonemd_supported(dns_rdata_t *rdata) {
+	REQUIRE(rdata != NULL);
+	REQUIRE(rdata->length >= 6);
+	REQUIRE(rdata->type == dns_rdatatype_zonemd);
+
+	switch (rdata->data[4]) {
+	case DNS_ZONEMD_SCHEME_SIMPLE:
+		switch (rdata->data[5]) {
+		case DNS_ZONEMD_DIGEST_SHA384:
+		case DNS_ZONEMD_DIGEST_SHA512:
+			return true;
+		default:
+			return false;
+		}
+	default:
+		return false;
+	}
+}