Hi,
On Wednesday, Jun 21, 2017 1:38 AM +0300, Maxim Dounin wrote:
>When the response is read from a static file, not proxied, and/or
>proxied with "proxy_method GET;", an empty response means exacly
>that: an empty response, and returning 415 is perfectly correct.
>
>The ngx_buf_size() test will limit the incorrect behaviour to
>indeed empty responses (previous version of your patch affected
>all non-image responses), but it won't eliminate incorrect behaviour
>for empty responses.
>
>The root cause of the problem is that in the configuration you've
>provided proxy don't know about image filter, and uses the HEAD
>method in the request to upstream filter despite the fact image
>filter needs a body to return proper response. This doesn't look
>like something easy to fix, as proper fix implies some knowledge
>to be passed between image filter and proxy.
>
>Most trivial solution, as suggested above, would be to use
>"proxy_method GET" explicitly in the configuration. It might be
>actually a good enough solution, as image filter is a special
>module and it requires proper configuration anyway.
Thank you for the detailed explanation. After reading the code again,
I still have two questions. First, is the following change appropriate ?
--- a/ngx_http_image_filter_module.c
+++ b/ngx_http_image_filter_module.c
@@ -330,6 +330,15 @@ ngx_http_image_body_filter(ngx_http_request_t *r,
ngx_chain_t *in)
}
}
+ if (r->method & NGX_HTTP_HEAD
+ && ctx->length
+ && ngx_buf_size(in->buf) == 0)
+ {
+ return ngx_http_filter_finalize_request(r,
+
&ngx_http_image_filter_module,
+ NGX_HTTP_NOT_ALLOWED);
+ }
+
return ngx_http_filter_finalize_request(r,
&ngx_http_image_filter_module,
NGX_HTTP_UNSUPPORTED_MEDIA_TYPE);
Second, Why not restrict the use of the image filter in the following way ?
--- a/ngx_http_image_filter_module.c
+++ b/ngx_http_image_filter_module.c
@@ -224,7 +224,9 @@ ngx_http_image_header_filter(ngx_http_request_t *r)
ngx_http_image_filter_ctx_t *ctx;
ngx_http_image_filter_conf_t *conf;
- if (r->headers_out.status == NGX_HTTP_NOT_MODIFIED) {
+ if (r->headers_out.status != NGX_HTTP_OK
+ && r->headers_out.status != NGX_HTTP_PARTIAL_CONTENT)
+ {
return ngx_http_next_header_filter(r);
}
Best wishes
-hucc
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