From 134e28ae5abc997fe064995627b3ebe247a5d5d8 Mon Sep 17 00:00:00 2001
From: Stefan Eissing <stefan@eissing.org>
Date: Fri, 23 Feb 2024 15:13:56 +0100
Subject: [PATCH] RESET stream after 100 failed incoming headers

---
 mod_http2/h2_session.c | 10 +++++++---
 mod_http2/h2_stream.c  |  1 +
 mod_http2/h2_stream.h  |  1 +
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/mod_http2/h2_session.c b/mod_http2/h2_session.c
index 1e560e47..6d379cc5 100644
--- a/mod_http2/h2_session.c
+++ b/mod_http2/h2_session.c
@@ -319,9 +319,13 @@ static int on_header_cb(nghttp2_session *ngh2, const nghttp2_frame *frame,
     
     status = h2_stream_add_header(stream, (const char *)name, namelen,
                                   (const char *)value, valuelen);
-    if (status != APR_SUCCESS
-        && (!stream->rtmp
-            || stream->rtmp->http_status == H2_HTTP_STATUS_UNSET)) {
+    if (status != APR_SUCCESS &&
+        (!stream->rtmp ||
+         stream->rtmp->http_status == H2_HTTP_STATUS_UNSET ||
+         /* We accept a certain amount of failures in order to reply
+          * with an informative HTTP error response like 413. But of the
+          * client is too wrong, we fail the request an RESET the stream */
+         stream->request_headers_failed > 100)) {
         return NGHTTP2_ERR_TEMPORAL_CALLBACK_FAILURE;
     }
     return 0;
diff --git a/mod_http2/h2_stream.c b/mod_http2/h2_stream.c
index f6c92024..ee87555f 100644
--- a/mod_http2/h2_stream.c
+++ b/mod_http2/h2_stream.c
@@ -813,6 +813,7 @@ apr_status_t h2_stream_add_header(h2_stream *stream,
     
 cleanup:
     if (error) {
+        ++stream->request_headers_failed;
         set_error_response(stream, error);
         return APR_EINVAL; 
     }
diff --git a/mod_http2/h2_stream.h b/mod_http2/h2_stream.h
index d68d4260..405978a4 100644
--- a/mod_http2/h2_stream.h
+++ b/mod_http2/h2_stream.h
@@ -91,6 +91,7 @@ struct h2_stream {
     struct h2_request *rtmp;    /* request being assembled */
     apr_table_t *trailers_in;   /* optional, incoming trailers */
     int request_headers_added;  /* number of request headers added */
+    int request_headers_failed; /* number of request headers failed to add */
 
 #if AP_HAS_RESPONSE_BUCKETS
     ap_bucket_response *response; /* the final, non-interim response or NULL */