From: Nick Porter <nick@portercomputing.co.uk>
Date: Thu, 17 Nov 2022 19:48:06 +0000 (+0000)
Subject: Add max_outstanding option to limit number of processing ldap_sync packets
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=481e54cf73039d05790e0bf92bfc596d7201d040;p=thirdparty%2Ffreeradius-server.git

Add max_outstanding option to limit number of processing ldap_sync packets
---

diff --git a/raddb/sites-available/ldap_sync b/raddb/sites-available/ldap_sync
index b32ef32fbe2..0d5ec357084 100644
--- a/raddb/sites-available/ldap_sync
+++ b/raddb/sites-available/ldap_sync
@@ -154,6 +154,14 @@ server ldap_sync {
 			#  How big the kernel's receive buffer should be.
 			#
 #			recv_buff = 1048576
+
+			#
+			#  Maximum number of updates to have outstanding
+			#  When this number is reached, no more are read, potentially
+			#  causing the receive buffer to fill which will cause the
+			#  change notifications to queue up on the LDAP server
+			#
+#			max_outstanding = 65536
 		}
 
 		#
diff --git a/src/listen/ldap_sync/proto_ldap_sync_ldap.c b/src/listen/ldap_sync/proto_ldap_sync_ldap.c
index 811ae27f4f8..d20beaa7038 100644
--- a/src/listen/ldap_sync/proto_ldap_sync_ldap.c
+++ b/src/listen/ldap_sync/proto_ldap_sync_ldap.c
@@ -58,6 +58,7 @@ static CONF_PARSER const proto_ldap_sync_ldap_config[] = {
 	 *	Network tunable parameters
 	 */
 	{ FR_CONF_OFFSET_IS_SET("recv_buff", FR_TYPE_UINT32, proto_ldap_sync_ldap_t, recv_buff) },
+	{ FR_CONF_OFFSET("max_outstanding", FR_TYPE_UINT32, proto_ldap_sync_ldap_t, max_outstanding), .dflt = "65536" },
 
 	CONF_PARSER_TERMINATOR
 };
@@ -592,6 +593,13 @@ static ssize_t proto_ldap_child_mod_read(fr_listen_t *li, UNUSED void **packet_c
 
 	fr_assert(conn);
 
+	/*
+	 *	If there are already too many outstanding requests just return.
+	 *	This will (potentially) cause the TCP buffer to fill and push the
+	 *	backpressure back to the LDAP server.
+	 */
+	if (fr_network_listen_outstanding(thread->nr, li) >= thread->inst->max_outstanding) return 0;
+
 	tree = talloc_get_type_abort(conn->uctx, fr_rb_tree_t);
 
 	/*
diff --git a/src/listen/ldap_sync/proto_ldap_sync_ldap.h b/src/listen/ldap_sync/proto_ldap_sync_ldap.h
index 3f4090f045e..8a430d0208a 100644
--- a/src/listen/ldap_sync/proto_ldap_sync_ldap.h
+++ b/src/listen/ldap_sync/proto_ldap_sync_ldap.h
@@ -103,6 +103,8 @@ typedef struct {
 
 	uint32_t			recv_buff;		//!< How big the kernel's recive buffer should be
 	bool				recv_buff_is_set;	//!< Whether we were provided with a recv_buff
+
+	uint32_t			max_outstanding;	//!< Maximun number of outstanding packets.
 } proto_ldap_sync_ldap_t;
 
 typedef struct {