If an error occurs in a SPDY connection, the c->error flag is set on every fake
request connection, and its read or write event handler is called, in order to
finalize it. But while waiting for request headers, it was a no-op since the
read event handler had been set to ngx_http_empty_handler().
If an error occurs in a SPDY connection, the c->error flag is set on every fake
request connection, and its read or write event handler is called, in order to
finalize it. But while waiting for a request body, it was a no-op since the
read event handler ngx_http_request_handler() calls r->read_event_handler that
had been set to ngx_http_block_reading().
They refer to the same socket descriptor as our real connection, and
deleting them will stop processing of the connection.
Events of fake connections must not be activated, and if it happened there
is nothing we can do. The whole processing should be terminated as soon as
possible, but it is not obvious how to do this safely.
A quote from SPDY draft 2 specification: "The length of each name and
value must be greater than zero. A receiver of a zero-length name or
value must send a RST_STREAM with code PROTOCOL error."
But it appears that Chrome browser allows sending requests over SPDY/2
connection using JavaScript that contain headers with empty values.
For better compatibility across SPDY clients and to be compliant with
HTTP, such headers are no longer rejected.
Also, it is worth noting that in SPDY draft 3 the statement has been
changed so that it permits empty values for headers.
It is possible to send FLAG_FIN in additional empty data frame, even if it is
known from the content-length header that request body is empty. And Firefox
actually behaves like this (see ticket #357).
To simplify code we sacrificed our microoptimization that did not work right
due to missing check in the ngx_http_spdy_state_data() function for rb->buf
set to NULL.
This is to avoid setting the TCP_NODELAY flag on SPDY socket in
ngx_http_upstream_send_response(). The latter works per request,
but in SPDY case it might affect other streams in connection.
