# HG changeset patch
# User Maxim Dounin <mdounin@mdounin.ru>
# Date 1617750209 -10800
# Node ID 3674d5b7174ee4b01865a3cb723a435ca98fdcb4
# Parent  e2e9e0fae74734b28974c64daacc492d751b4781
HTTP/2: relaxed PRIORITY frames limit.

Firefox uses several idle streams for PRIORITY frames[1], and
"http2_max_concurrent_streams 1;" results in "client sent too many
PRIORITY frames" errors when a connection is established by Firefox.

Fix is to relax the PRIORITY frames limit to use at least 100 as
the initial value (which is the recommended by the HTTP/2 protocol
minimum limit on the number of concurrent streams, so it is not
unreasonable for clients to assume that similar number of idle streams
can be used for prioritization).

[1] https://hg.mozilla.org/mozilla-central/file/32a9e6e145d6e3071c3993a20bb603a2f388722b/netwerk/protocol/http/Http2Stream.cpp#l1270

diff --git a/src/http/v2/ngx_http_v2.c b/src/http/v2/ngx_http_v2.c
--- a/src/http/v2/ngx_http_v2.c
+++ b/src/http/v2/ngx_http_v2.c
@@ -277,7 +277,7 @@ ngx_http_v2_init(ngx_event_t *rev)
     h2scf = ngx_http_get_module_srv_conf(hc->conf_ctx, ngx_http_v2_module);
 
     h2c->concurrent_pushes = h2scf->concurrent_pushes;
-    h2c->priority_limit = h2scf->concurrent_streams;
+    h2c->priority_limit = ngx_max(h2scf->concurrent_streams, 100);
 
     h2c->pool = ngx_create_pool(h2scf->pool_size, h2c->connection->log);
     if (h2c->pool == NULL) {