[PATCH] Enable HTTP/2 by default.

[Auke Kok]

Adds a `nohttp2` option to explicitly disable HTTP/2 support.
---
 contrib/vim/syntax/nginx.vim    | 2 +-
 src/http/ngx_http_core_module.c | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/contrib/vim/syntax/nginx.vim b/contrib/vim/syntax/nginx.vim
index 075b19a..8cff3e0 100644
--- a/contrib/vim/syntax/nginx.vim
+++ b/contrib/vim/syntax/nginx.vim
@@ -62,7 +62,7 @@ syn match ngxListenComment '#.*$'
     \ contained
     \ nextgroup=@ngxListenParams skipwhite skipempty
 syn keyword ngxListenOptions contained
-    \ default_server ssl http2 proxy_protocol
+    \ default_server ssl http2 nohttp2 proxy_protocol
     \ setfib fastopen backlog rcvbuf sndbuf accept_filter deferred bind
     \ ipv6only reuseport so_keepalive
     \ nextgroup=@ngxListenParams skipwhite skipempty
diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index 6b318dd..c7b5c72 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -3773,6 +3773,9 @@ ngx_http_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
     lsopt.backlog = NGX_LISTEN_BACKLOG;
     lsopt.rcvbuf = -1;
     lsopt.sndbuf = -1;
+#if (NGX_HTTP_V2)
+    lsopt.http2 = 1;
+#endif
 #if (NGX_HAVE_SETFIB)
     lsopt.setfib = -1;
 #endif
@@ -3975,7 +3978,6 @@ ngx_http_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 
         if (ngx_strcmp(value[n].data, "http2") == 0) {
 #if (NGX_HTTP_V2)
-            lsopt.http2 = 1;
             continue;
 #else
             ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
@@ -3985,6 +3987,11 @@ ngx_http_core_listen(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
 #endif
         }
 
+        if (ngx_strcmp(value[n].data, "nohttp2") == 0) {
+            lsopt.http2 = 0;
+            continue;
+        }
+
         if (ngx_strcmp(value[n].data, "spdy") == 0) {
             ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                                "invalid parameter \"spdy\": "
-- 
2.21.0