From 933f7b79949bc588945672396d70b661143bb8f0 Mon Sep 17 00:00:00 2001
From: Nick Banks <nibanks@microsoft.com>
Date: Fri, 12 Jan 2024 15:11:49 -0500
Subject: [PATCH] Abandon Connections with Too Many Retired CIDs

---
 src/core/connection.c     | 10 ++++++++++
 src/core/connection.h     |  5 +++++
 src/core/loss_detection.c |  2 ++
 3 files changed, 17 insertions(+)

diff --git a/src/core/connection.c b/src/core/connection.c
index 3612abcf24..6f63cc0e56 100644
--- a/src/core/connection.c
+++ b/src/core/connection.c
@@ -990,6 +990,16 @@ QuicConnRetireCid(
     DestCid->CID.Retired = TRUE;
     DestCid->CID.NeedsToSend = TRUE;
     QuicSendSetSendFlag(&Connection->Send, QUIC_CONN_SEND_FLAG_RETIRE_CONNECTION_ID);
+
+    Connection->RetiredDestCidCount++;
+    if (Connection->RetiredDestCidCount > 8 * QUIC_ACTIVE_CONNECTION_ID_LIMIT) {
+        QuicTraceEvent(
+            ConnError,
+            "[conn][%p] ERROR, %s.",
+            Connection,
+            "Peer exceeded retire CID limit");
+        QuicConnSilentlyAbort(Connection);
+    }
 }
 
 _IRQL_requires_max_(PASSIVE_LEVEL)
diff --git a/src/core/connection.h b/src/core/connection.h
index b347b3c70c..7c1bcbe62f 100644
--- a/src/core/connection.h
+++ b/src/core/connection.h
@@ -392,6 +392,11 @@ typedef struct QUIC_CONNECTION {
     //
     uint8_t DestCidCount;
 
+    //
+    // Number of retired desintation CIDs we currently have cached.
+    //
+    uint8_t RetiredDestCidCount;
+
     //
     // The maximum number of source CIDs to give the peer. This is a minimum of
     // what we're willing to support and what the peer is willing to accept.
diff --git a/src/core/loss_detection.c b/src/core/loss_detection.c
index e4356c202a..d8bce352ce 100644
--- a/src/core/loss_detection.c
+++ b/src/core/loss_detection.c
@@ -608,6 +608,8 @@ QuicLossDetectionOnPacketAcknowledged(
                 CXPLAT_DBG_ASSERT(DestCid->CID.Retired);
                 CXPLAT_DBG_ASSERT(Path == NULL || Path->DestCid != DestCid);
                 QUIC_CID_VALIDATE_NULL(Connection, DestCid);
+                CXPLAT_DBG_ASSERT(Connection->RetiredDestCidCount > 0);
+                Connection->RetiredDestCidCount--;
                 CXPLAT_FREE(DestCid, QUIC_POOL_CIDLIST);
             }
             break;