From e5fc9f5fcbd7f3d0dae8468bec1b801d5a692dba Mon Sep 17 00:00:00 2001
From: Colin Vidal <colin@isc.org>
Date: Wed, 29 Jan 2025 23:27:34 +0100
Subject: [PATCH] detect dup EDE with bitmap and store next pos

In order to avoid to loop to find the next position to store an EDE in
a dns_edectx_t, add a "nextede" state which holds the next available
position.

Also, in order ot avoid to loop to find if an EDE is already existing in
a dns_edectx_t, and avoid a duplicate, use a bitmap to immediately know
if the EDE is there or not.

Those both changes applies for adding or copying EDE.

Also make the direction of dns_ede_copy more explicit/avoid errors by
making "edectx_from" a const pointer.

(cherry picked from commit 9021f9d802296241dc69431407551d824beeb814)
---
 lib/dns/ede.c             | 63 ++++++++++++++++++++-------------------
 lib/dns/include/dns/ede.h |  4 ++-
 2 files changed, 36 insertions(+), 31 deletions(-)

diff --git a/lib/dns/ede.c b/lib/dns/ede.c
index 7dcb05f281..7fbbd83905 100644
--- a/lib/dns/ede.c
+++ b/lib/dns/ede.c
@@ -21,38 +21,39 @@
 #define DNS_EDE_MAGIC	 ISC_MAGIC('E', 'D', 'E', '!')
 #define DNS_EDE_VALID(v) ISC_MAGIC_VALID(v, DNS_EDE_MAGIC)
 
+static bool
+dns__ede_checkandupdateedeused(dns_edectx_t *edectx, uint16_t code) {
+	if (edectx->edeused & (1 << code)) {
+		return true;
+	}
+
+	edectx->edeused |= 1 << code;
+	return false;
+}
+
 void
 dns_ede_add(dns_edectx_t *edectx, uint16_t code, const char *text) {
 	REQUIRE(DNS_EDE_VALID(edectx));
 	REQUIRE(code <= DNS_EDE_MAX_CODE);
 
-	size_t pos = 0;
 	uint16_t becode = htobe16(code);
 	dns_ednsopt_t *edns = NULL;
 	size_t textlen = 0;
 
-	for (pos = 0; pos < DNS_EDE_MAX_ERRORS; pos++) {
-		edns = edectx->ede[pos];
-
-		if (edns == NULL) {
-			break;
-		}
-
-		if (memcmp(&becode, edns->value, sizeof(becode)) == 0) {
-			isc_log_write(DNS_LOGCATEGORY_RESOLVER,
-				      DNS_LOGMODULE_RESOLVER, ISC_LOG_DEBUG(1),
-				      "ignoring duplicate ede %u %s", code,
-				      text == NULL ? "(null)" : text);
-			return;
-		}
+	if (dns__ede_checkandupdateedeused(edectx, code)) {
+		isc_log_write(DNS_LOGCATEGORY_RESOLVER, DNS_LOGMODULE_RESOLVER,
+			      ISC_LOG_DEBUG(1), "ignoring duplicate ede %u %s",
+			      code, text == NULL ? "(null)" : text);
+		return;
 	}
 
-	if (pos >= DNS_EDE_MAX_ERRORS) {
+	if (edectx->nextede >= DNS_EDE_MAX_ERRORS) {
 		isc_log_write(DNS_LOGCATEGORY_RESOLVER, DNS_LOGMODULE_RESOLVER,
 			      ISC_LOG_DEBUG(1), "too many ede, ignoring %u %s",
 			      code, text == NULL ? "(null)" : text);
 		return;
 	}
+	INSIST(edectx->ede[edectx->nextede] == NULL);
 
 	isc_log_write(DNS_LOGCATEGORY_RESOLVER, DNS_LOGMODULE_RESOLVER,
 		      ISC_LOG_DEBUG(1), "set ede: info-code %u extra-text %s",
@@ -83,7 +84,8 @@ dns_ede_add(dns_edectx_t *edectx, uint16_t code, const char *text) {
 		memmove(edns->value + sizeof(becode), text, textlen);
 	}
 
-	edectx->ede[pos] = edns;
+	edectx->ede[edectx->nextede] = edns;
+	edectx->nextede++;
 }
 
 void
@@ -113,6 +115,8 @@ dns_ede_reset(dns_edectx_t *edectx) {
 		isc_mem_put(edectx->mctx, edns, sizeof(*edns) + edns->length);
 		edectx->ede[i] = NULL;
 	}
+
+	dns_ede_init(edectx->mctx, edectx);
 }
 
 void
@@ -126,31 +130,30 @@ dns_ede_invalidate(dns_edectx_t *edectx) {
 }
 
 void
-dns_ede_copy(dns_edectx_t *edectx_to, dns_edectx_t *edectx_from) {
+dns_ede_copy(dns_edectx_t *edectx_to, const dns_edectx_t *edectx_from) {
 	REQUIRE(DNS_EDE_VALID(edectx_to));
 	REQUIRE(DNS_EDE_VALID(edectx_from));
 
-	size_t nextede = 0;
-
-	for (nextede = 0; nextede < DNS_EDE_MAX_ERRORS; nextede++) {
-		if (edectx_to->ede[nextede] == NULL) {
-			break;
-		}
-	}
-
 	for (size_t pos = 0; pos < DNS_EDE_MAX_ERRORS; pos++) {
+		uint16_t fromcode;
+
 		if (edectx_from->ede[pos] == NULL) {
 			break;
 		}
 
-		if (nextede >= DNS_EDE_MAX_ERRORS) {
+		fromcode = ISC_U8TO16_BE(edectx_from->ede[pos]->value);
+		if (dns__ede_checkandupdateedeused(edectx_to, fromcode)) {
+			continue;
+		}
+
+		if (edectx_to->nextede >= DNS_EDE_MAX_ERRORS) {
 			isc_log_write(DNS_LOGCATEGORY_RESOLVER,
 				      DNS_LOGMODULE_RESOLVER, ISC_LOG_DEBUG(1),
 				      "too many ede from subfetch");
 			break;
 		}
 
-		INSIST(edectx_to->ede[nextede] == NULL);
+		INSIST(edectx_to->ede[edectx_to->nextede] == NULL);
 
 		dns_ednsopt_t *edns = isc_mem_get(
 			edectx_to->mctx,
@@ -163,7 +166,7 @@ dns_ede_copy(dns_edectx_t *edectx_to, dns_edectx_t *edectx_from) {
 		memmove(edns->value, edectx_from->ede[pos]->value,
 			edectx_from->ede[pos]->length);
 
-		edectx_to->ede[nextede] = edns;
-		nextede++;
+		edectx_to->ede[edectx_to->nextede] = edns;
+		edectx_to->nextede++;
 	}
 }
diff --git a/lib/dns/include/dns/ede.h b/lib/dns/include/dns/ede.h
index 8f6cf3bf9a..37194dd5ef 100644
--- a/lib/dns/include/dns/ede.h
+++ b/lib/dns/include/dns/ede.h
@@ -63,6 +63,8 @@ struct dns_edectx {
 	int	       magic;
 	isc_mem_t     *mctx;
 	dns_ednsopt_t *ede[DNS_EDE_MAX_ERRORS];
+	uint32_t       edeused;
+	size_t	       nextede;
 };
 /*%<
  * Multiple extended DNS errors (EDE) (defined in RFC 8914) can be raised during
@@ -132,7 +134,7 @@ dns_ede_add(dns_edectx_t *edectx, uint16_t code, const char *text);
  */
 
 void
-dns_ede_copy(dns_edectx_t *edectx_to, dns_edectx_t *edectx_from);
+dns_ede_copy(dns_edectx_t *edectx_to, const dns_edectx_t *edectx_from);
 /*%<
  * Copy all EDE from "edectx_from" into "edectx_to". If "edectx_to" reaches the
  * maximum number of EDE (see DNS_EDE_MAX_ERRORS), the copy stops and