[PATCH 5 of 5] QUIC: limited the total number of frames

[Roman Arutyunyan]

# HG changeset patch
# User Roman Arutyunyan <arut at nginx.com>
# Date 1633603050 -10800
#      Thu Oct 07 13:37:30 2021 +0300
# Branch quic
# Node ID 25aeebb9432182a6246fedba6b1024f3d61e959b
# Parent  e20f00b8ac9005621993ea19375b1646c9182e7b
QUIC: limited the total number of frames.

Exceeding 10000 allocated frames is considered a flood.

diff --git a/src/event/quic/ngx_event_quic_connection.h b/src/event/quic/ngx_event_quic_connection.h
--- a/src/event/quic/ngx_event_quic_connection.h
+++ b/src/event/quic/ngx_event_quic_connection.h
@@ -228,10 +228,8 @@ struct ngx_quic_connection_s {
     ngx_chain_t                      *free_bufs;
     ngx_buf_t                        *free_shadow_bufs;
 
-#ifdef NGX_QUIC_DEBUG_ALLOC
     ngx_uint_t                        nframes;
     ngx_uint_t                        nbufs;
-#endif
 
     ngx_quic_streams_t                streams;
     ngx_quic_congestion_t             congestion;
diff --git a/src/event/quic/ngx_event_quic_frames.c b/src/event/quic/ngx_event_quic_frames.c
--- a/src/event/quic/ngx_event_quic_frames.c
+++ b/src/event/quic/ngx_event_quic_frames.c
@@ -38,18 +38,22 @@ ngx_quic_alloc_frame(ngx_connection_t *c
                        "quic reuse frame n:%ui", qc->nframes);
 #endif
 
-    } else {
+    } else if (qc->nframes < 10000) {
         frame = ngx_palloc(c->pool, sizeof(ngx_quic_frame_t));
         if (frame == NULL) {
             return NULL;
         }
 
-#ifdef NGX_QUIC_DEBUG_ALLOC
         ++qc->nframes;
 
+#ifdef NGX_QUIC_DEBUG_ALLOC
         ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                        "quic alloc frame n:%ui", qc->nframes);
 #endif
+
+    } else {
+        ngx_log_error(NGX_LOG_INFO, c->log, 0, "quic flood detected");
+        return NULL;
     }
 
     ngx_memzero(frame, sizeof(ngx_quic_frame_t));
@@ -372,9 +376,9 @@ ngx_quic_alloc_buf(ngx_connection_t *c)
 
     cl->buf = b;
 
-#ifdef NGX_QUIC_DEBUG_ALLOC
     ++qc->nbufs;
 
+#ifdef NGX_QUIC_DEBUG_ALLOC
     ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                    "quic alloc buffer n:%ui", qc->nbufs);
 #endif