HTTP/2: fixed buffer management with HTTP/2 auto-detection. As part of normal HTTP/2 processing, incomplete frames are saved in the control state using a fixed size memcpy of NGX_HTTP_V2_STATE_BUFFER_SIZE. For this matter, two state buffers are reserved in the HTTP/2 recv buffer. As part of HTTP/2 auto-detection on plain TCP connections, initial data is first read into a buffer specified by the client_header_buffer_size directive that doesn't have state reservation. Previously, this made it possible to over-read the buffer as part of saving the state. The fix is to read the available buffer size rather than a fixed size. Although memcpy of a fixed size can produce a better optimized code, handling of incomplete frames isn't a common execution path, so it was sacrificed for the sake of simplicity of the fix.

uwsgi_param  QUERY_STRING       $query_string;
uwsgi_param  REQUEST_METHOD     $request_method;
uwsgi_param  CONTENT_TYPE       $content_type;
uwsgi_param  CONTENT_LENGTH     $content_length;

uwsgi_param  REQUEST_URI        $request_uri;
uwsgi_param  PATH_INFO          $document_uri;
uwsgi_param  DOCUMENT_ROOT      $document_root;
uwsgi_param  SERVER_PROTOCOL    $server_protocol;
uwsgi_param  REQUEST_SCHEME     $scheme;
uwsgi_param  HTTPS              $https if_not_empty;

uwsgi_param  REMOTE_ADDR        $remote_addr;
uwsgi_param  REMOTE_PORT        $remote_port;
uwsgi_param  SERVER_PORT        $server_port;
uwsgi_param  SERVER_NAME        $server_name;