# HG changeset patch
# User Sergey Kandaurov <pluknet@nginx.com>
# Date 1592902620 -10800
# Node ID df29219988bcf160b838e368ac275474c3465c74
# Parent  3de1b739965044c0a1737223f0620886cb7822a3
Discard short packets which could not be decrypted.

So that connections are protected from failing from on-path attacks.
Decryption failure of long packets used during handshake still leads
to connection close since it barely makes sense to handle them there.

diff --git a/src/event/ngx_event_quic.c b/src/event/ngx_event_quic.c
--- a/src/event/ngx_event_quic.c
+++ b/src/event/ngx_event_quic.c
@@ -1830,9 +1830,11 @@ ngx_quic_app_input(ngx_connection_t *c, 
 
     ctx = ngx_quic_get_send_ctx(qc, pkt->level);
 
-    if (ngx_quic_decrypt(pkt, c->ssl->connection, &ctx->largest_pn) != NGX_OK) {
+    rc = ngx_quic_decrypt(pkt, c->ssl->connection, &ctx->largest_pn);
+
+    if (rc != NGX_OK) {
         qc->error = pkt->error;
-        return NGX_ERROR;
+        return rc;
     }
 
     /* switch keys on Key Phase change */
diff --git a/src/event/ngx_event_quic_protection.c b/src/event/ngx_event_quic_protection.c
--- a/src/event/ngx_event_quic_protection.c
+++ b/src/event/ngx_event_quic_protection.c
@@ -1051,7 +1051,7 @@ ngx_quic_decrypt(ngx_quic_header_t *pkt,
         != NGX_OK)
     {
         pkt->error = NGX_QUIC_ERR_PROTOCOL_VIOLATION;
-        return NGX_ERROR;
+        return NGX_DECLINED;
     }
 
     if (ngx_quic_long_pkt(pkt->flags)) {
@@ -1131,7 +1131,7 @@ ngx_quic_decrypt(ngx_quic_header_t *pkt,
 
     if (rc != NGX_OK) {
         pkt->error = NGX_QUIC_ERR_PROTOCOL_VIOLATION;
-        return rc;
+        return NGX_DECLINED;
     }
 
     if (badflags) {