chunked request bodies not supported yet - lua-resty-upload

[Michael Hock]

Hi,

I am experiencing issues when trying to upload a file with chunked request bodies.

I already tried to debug this issue, and it doesn't seem to be the client which causes issues. So it has to do something with the nginx core itself or lua.

Here's what I'm sending to the server:

POST /ul/8R1Jg_IST4w HTTP/1.1
Host: EXAMPLE.COM
User-Agent: upload test
Accept: * /*; q=0.01
Content-Type: multipart/form-data; boundary=---------------------------16470503901521535624504986122
Connection: close
Transfer-Encoding: chunked
Pragma: no-cache
Cache-Control: no-cache

b2
-----------------------------16470503901521535624504986122
Content-Disposition: form-data; name="file1"; filename="test.dat"
Content-Type: application/x-ns-proxy-autoconfig


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40

-----------------------------16470503901521535624504986122--

0

And this is the response:

HTTP/1.1 500 Internal Server Error
Server: openresty
Date: Fri, 03 Apr 2015 19:48:31 GMT
Content-Type: application/json
Transfer-Encoding: chunked
Connection: close

4f
{"status":500,"msg":"upload failed: chunked request bodies not supported yet"}

0

The relevant lua code for resty upload (nothing special):

local upload = require "resty.upload"
local chunk_size = 16384 -- should be set to >4096 for real-world settings
require "functions"

-- some more code which has nothign to to with uploading

local form, err = upload:new(chunk_size)
if not form then
    displayError("upload failed: " .. err, 500) -- displayError is defined in functions.lua and adds error to nginx log and outputs in json format
end

Is there anything I am doing wrong here, or are chunked POST's just not supported by nginx/openresty?

Thanks for your help!

[Michael Hock]

Sorry, forgot the most important thing:
I'm using nginx version: openresty/1.7.10.1

[Yichun Zhang (agentzh)]

Hello!

On Fri, Apr 3, 2015 at 12:59 PM, Michael Hock wrote:
> I am experiencing issues when trying to upload a file with chunked request
> bodies.
>

Yeah, the ngx.req.socket() API function [1] used by lua-resty-upload
does not support chunked encoding yet. Adding the support has been on
my TODO list. Patches welcome as always :)

Best regards,
-agentzh

[1] https://github.com/openresty/lua-nginx-module#ngxreqsocket

[Michael]

Hello agentzh,

Thank you for your very fast response! :)

Unfortunately, I'm not into the C programming that much, so I doubt I would be of any help here ... :(

Is there any other possibility you can think of to send data to lua-resty-upload without knowing the acutal size in advance?

Thanks, best regards and happy easter holidays!

Michael

[Yichun Zhang (agentzh)]

Hello!

On Sat, Apr 4, 2015 at 4:27 AM, Michael wrote:
> Is there any other possibility you can think of to send data to
> lua-resty-upload without knowing the acutal size in advance?
>

There does exist a work-around for reading the chunked request body
data in a streaming fashion, via using the "raw" request socket (i.e.,
ngx.req.socket(true)), as demonstrated by the following (declarative)
test case in ngx_lua' existing test suite:

https://github.com/openresty/lua-nginx-module/blob/75cc29ea64a87bc5cd447525893fda76b8d664b4/t/116-raw-req-socket.t#L784

But it would require some more work to make it work with
lua-resty-upload. Good luck with this (dirty) route :)

The most beautiful way to achieve this, however, as I've said in my
previous email, is to make the non-raw request socket API support
chunked encoding transparently, such that existing Lua libraries like
lua-resty-upload will just work with chunked request bodies out of the
box.

Regards,
-agentzh

[Michael]

Hello agentz!

I had a look on the work-around with lua, but it seems too much work needs to be done to get it working with the lua-resty-upload module. Also, I like the solution with a lua-nginx-module modification better ...
Therefore I tried to implement it directly in nginx.
I looked at the function static int ngx_http_lua_req_socket(lua_State *L) in ngx_http_lua_socket_tcp.c, because the error with chunked request bodies gets thrown there.
I know I can check if the request is a chunked request by checking r->headers_in.chunked.
I tried to use the function ngx_http_parse_chunked(ngx_http_request_t *r, ngx_buf_t *b, ngx_http_chunked_t *ctx); when it's a chunked request in the bottom of the /* request body reader */ part, but I never managed to get any data to lua.
The function seemed to be the key for me, because it's also used in some changes where nginx added support for chunked request bodies:
https://github.com/nginx/nginx/commit/a79aeb7ca33d55f3bed89062b1bdfe24ee9a46cb

But to be honest, I have not much of an idea on which place modifications are to be done, so that lua gets the un-chunked-encoded data ...
Would it be possible to tell roughly in which parts changes need to be done?

Thank you!

Best Regards,
Michael