Thanks guys for your replies. I have previously looked at how NGX_AGAIN is handled in the nginx source, and its along the lines of [i]if ngx_http_read_client_request_body returns anything other than NGX_OK, return that from the module, otherwise return NGX_DONE[/i]. The problem is when I do this, my module is never called again.

@Mike: I have tried what you described and it it promising in the sense that it appears that my handler function (2nd arg to ngx_http_read_client_request_body()) gets called again, but the handler function never returns to the main-line code of the module. Is this supposed to be expected behavior?

I'm just confused because the way this is handled in the Nginx source does not seem to work, even though some people such as as http://markmail.org/message/knchl7ricknggvws have had success with it.