mod_proxy(es): Avoid error response/document handling by the core if some

input filter already did it while reading client's payload.

When an input filter returns AP_FILTER_ERROR, it has already called ap_die()
or at least already responded to the client.

Here we don't want to lose AP_FILTER_ERROR when returning from proxy handlers,
so we use ap_map_http_request_error() to forward any AP_FILTER_ERROR to
ap_die() which knows whether a response needs to be completed or not.

Before this commit, returning an HTTP error code in this case caused a double
response to be generated.

Depends on r1657881 to preserve r->status (for logging) when nothing is to be
done by ap_die() when handling AP_FILTER_ERROR.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1657897 13f79535-47bb-0310-9956-ffa450edef68

modules/proxy/mod_proxy_balancer.c

@@ -1039,7 +1039,7 @@ static int balancer_handler(request_rec *r)
         rv = ap_get_brigade(r->input_filters, ib, AP_MODE_READBYTES,
                                 APR_BLOCK_READ, len);
         if (rv != APR_SUCCESS) {
-            return HTTP_INTERNAL_SERVER_ERROR;
+            return ap_map_http_request_error(rv, HTTP_BAD_REQUEST);
         }
         apr_brigade_flatten(ib, buf, &len);
         buf[len] = '\0';