@Maxim: nice hints, thanks. Let me ask you about filters order. To get the contents that will be sent to client, I want to run my body_filter right before the gziping. How to accomplish that or if it is even possible
I am worried that copying the buffers content the original ones can be yet modified by other filters and than I will log an outdated copy. Thanks for your help. On Fri, May 23, 2014 at 10:12 AM, Maxim Dounin <mdou...@mdounin.ru> wrote: > Hello! > > On Thu, May 22, 2014 at 03:21:56PM +0100, Paulo Silva wrote: > >> Hi, >> Let me introduce the Elephant in the room. My name is Paulo and I'm >> from Portugal. >> I am starting developing nginx modules and I'm having a great time >> with buffers chain :D >> >> I'm using nginx as a reverse proxy and my goal is to log the full >> response body (HTML) on the server. >> >> I did start with a filter module with a body_filter and my approach is >> as follow: >> >> 1. Inspect given ngx_chain_t *in linked list to understand if nginx >> has the full response (last_buf) >> 2. On each body_filter call I'm updating a linked list which glues >> given ngx_chain_t *in to the previous ones. >> 3. As soon as I detect the last_buf, I iterate my internal linked list >> (and each linked ngx_chain_t lists), dumping buffers content. >> >> Although I'm reaching the last_buf, I'm missing some bytes. > > In no particular order: > > - Make sure you are allocating your own ngx_chain_t structures. > Trying to modify ngx_chain_t structures got in *in chain is a > common mistake. > > - If you are passing buffers to next filters, it's incorrect to > assume that buffer contents will be available later (a buffer > contents will be eventually sent to a client, and then the > buffer can be reused by its owner). > > - If you are not passing buffers to next filters, it's incorrect > to assume that you'll get full response (e.g., with > "output_buffers 1 64", you'll get only first 64 bytes of a > response). > > - If you didn't set r->filter_need_in_memory, it's incorrect to > assume that buffers will be in memory. > > To log a response body, you'll have to copy contents of all > buffers sent though your filter. Just saving links to buffers is > certainly not enough. > > -- > Maxim Dounin > http://nginx.org/ > > _______________________________________________ > nginx-devel mailing list > nginx-devel@nginx.org > http://mailman.nginx.org/mailman/listinfo/nginx-devel -- Paulo A. Silva http://tech.pauloasilva.com http://linkedin.com/in/devpauloasilva/ _______________________________________________ nginx-devel mailing list nginx-devel@nginx.org http://mailman.nginx.org/mailman/listinfo/nginx-devel
