post body

[Dk Jack]

Haven't received any response to inquiry. Would appreciate it if someone
can comment.

Thanks,
Dk.

On Thu, Aug 2, 2018 at 12:29 PM Dk Jack <dnj0496 at gmail.com> wrote:

> Hi,
> In my module, I'd like to look into the post body to decide if the request
> should be allowed to proceed to origin server or not. Based on the examples
> I could find I've coded this in my module. After some trial and error it
> seems to be working. I am not sure if my implementation is 100% correct. I
> would appreciate it if someone can go over my code below and let me know if
> my implementation is correct. Especially, the body_complete_handler. Thanks.
>
> Regards,
> Dk.
>
>
> static ngx_int_t mod_setup_body_handler(ngx_http_request_t* r);
> static void mod_body_complete_handler(ngx_http_request_t* r);
> static ngx_int_t mod_extract_post_body(ngx_http_request_t *r, char *data,
> size_t *dsize);
>
> static ngx_int_t
> ngx_http_request_handler(ngx_http_request_t *r)
> {
>   ....
>   if ((NGX_HTTP_POST == r->method) || (NGX_HTTP_PUT == r->method)) {
>     return mod_setup_body_handler(r);
>   }
>
>   ...
> }
>
> ngx_int_t
> mod_setup_body_handler(ngx_http_request_t* r)
> {
>   ngx_int_t rc;
>
>   r->request_body_in_single_buf = 1;
>   r->request_body_in_persistent_file = 1;
>   r->request_body_in_clean_file = 1;
>
>   rc = ngx_http_read_client_request_body(r, mod_body_complete_handler);
>   if (rc == NGX_ERROR) {
>     ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "read req. body
> error");
>     return rc;
>   }
>
>   if (rc == NGX_ERROR || rc >= NGX_HTTP_SPECIAL_RESPONSE) {
>     ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "read req. body
> error. special response");
>     return rc;
>   }
>
>   if (rc == NGX_AGAIN) {
>     /*
>      * nginx will call the body_received when needed. Returning
>      * NGX_DONE will prevent nginx from calling ngx_http_finalize_request
>      * (which we will call in body_received)
>      */
>     return NGX_DONE;
>   }
>
>   return NGX_DECLINED;
> }
>
>
> void
> mod_body_complete_handler(ngx_http_request_t* r)
> {
>   ngx_http_request_t* r = mNginxRequest;
>
>   if(r->request_body == NULL) {
>     // callback was called but body is empty. Setup handler again.
>     mod_setup_body_handler(bh_ptr);
>     return;
>   } else if (r->request_body->rest) {
>     // we don't have the complete body. Complete callback will be called
> again.
>     return;
>   }
>
>   if (NULL == mNginxRequest->request_body->temp_file) {
>     size_t dsize = 64*1024;
>     char data[dsize]
>
>     if (mod_extract_post_body(r, data, dsize) == NGX_OK) {
>       // we have the complete body.
>       int rc = mod_allow_request(body, dsize);  // returns NGX_OK or 4XX.
>
>       if (rc != NGX_OK) {
>         // allow req. has already sent a custom response if rc != NGX_OK.
>         ngx_http_finalize_request(r, NGX_OK);
>         return;
>       }
>     }
>   }
>
>   // ???? not having this cause request to hang.
>   ngx_http_core_run_phases(r);
> }
>
> ngx_int_t
> mod_extract_post_body(ngx_http_request_t *r, char *data, size_t *dsize)
> {
>   size_t buf_size = *dsize;
>
>   if (NULL == r->request_body->temp_file) {
>     // we have body in buffer chain.
>     ngx_buf_t *buf;
>     ngx_chain_t *cl;
>     size_t data_start_pos = 0;
>
>     cl = r->request_body->bufs;
>
>     // copy the body into our temporary buffer.
>     for (;NULL != cl; cl = cl->next) {
>       buf = cl->buf;
>       size_t bsize = buf->last - buf->pos;
>
>       if ((data_start_pos+bsize) > buf_size) {
>         // data is bigger than the input buffer size, abort
>         *dsize = data_start_pos;
>         *(data+*dsize) = '\0';
>         return NGX_ERROR;
>       }
>
>       ngx_memcpy((data+data_start_pos), buf->pos, bsize);
>       data_start_pos += bsize;
>     }
>
>     *dsize = data_start_pos;
>     *(data+*dsize) = '\0';
>     return NGX_OK;
>   } else {
>     // body in file not implemented yet.
>   }
>
>   return NGX_ERROR;
> }
>
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