Hello!

According to the current implementation of ngx_http_upstream, there is
almost no way for 3rd-party output body filters and "post_subrequest"
handlers (in the subrequest context) to know if there's any errors
while ngx_http_upstream is processing the upstream response body after
the response header is sent out (in both the buffered and non-buffered
modes).

For example, if

1. a read-timeout happens in the middle of the process of reading the
upstream response body,
2. or the upstream connection is closed prematurely in the same situation,

then ngx_http_upstream will just happily finalize the current request
with the status code 0 (i.e., NGX_OK). This issue already affects at
least our ngx_srcache and ngx_lua modules (originally reported by
Bryan Alger).

Here attaches a patch that makes ngx_http_upstream set
r->headers_out.status to a new error status code to notify the outside
world if there is a problem. Comments will be highly appreciated as
always :)

Thanks!
-agentzh

--- nginx-1.2.3/src/http/ngx_http_upstream.c 2012-08-06 10:34:08.000000000 -0700
+++ nginx-1.2.3-patched/src/http/ngx_http_upstream.c 2012-09-09
21:58:04.727761891 -0700
@@ -2383,7 +2383,7 @@

if (c->read->timedout) {
ngx_connection_error(c, NGX_ETIMEDOUT, "upstream timed out");
- ngx_http_upstream_finalize_request(r, u, 0);
+ ngx_http_upstream_finalize_request(r, u, NGX_HTTP_GATEWAY_TIME_OUT);
return;
}

@@ -2430,13 +2430,17 @@
if (u->busy_bufs == NULL) {

if (u->length == 0
- || upstream->read->eof
- || upstream->read->error)
+ || (upstream->read->eof &&
u->headers_in.content_length_n == -1))
{
ngx_http_upstream_finalize_request(r, u, 0);
return;
}

+ if (upstream->read->eof || upstream->read->error) {
+ ngx_http_upstream_finalize_request(r, u,
NGX_HTTP_BAD_GATEWAY);
+ return;
+ }
+
b->pos = b->start;
b->last = b->start;
}
@@ -2710,7 +2714,16 @@
#if 0
ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
#endif
- ngx_http_upstream_finalize_request(r, u, 0);
+
+ if (p->upstream_done
+ || (p->upstream_eof && u->headers_in.content_length_n == -1))
+ {
+ ngx_http_upstream_finalize_request(r, u, 0);
+
+ } else {
+ ngx_http_upstream_finalize_request(r, u, NGX_HTTP_BAD_GATEWAY);
+ }
+
return;
}
}
@@ -3073,6 +3086,13 @@
&& rc != NGX_HTTP_REQUEST_TIME_OUT
&& (rc == NGX_ERROR || rc >= NGX_HTTP_SPECIAL_RESPONSE))
{
+ if (rc == NGX_ERROR) {
+ r->headers_out.status = NGX_HTTP_INTERNAL_SERVER_ERROR;
+
+ } else {
+ r->headers_out.status = rc;
+ }
+
rc = 0;
}
_______________________________________________
nginx-devel mailing list
nginx-devel@nginx.org
http://mailman.nginx.org/mailman/listinfo/nginx-devel