Uclient-fetch: POST Content-length

Installing and Using OpenWrt
1

Running openwrt-18.06 branch (git-18.228.31946-f64b152)

When submitting a POST request using built-in wget command (which is actually uclient-fetch), the Content-Length is not present. Example:

wget --post-data="a=b" http://httpbin.org/post -O -

Server receive the following headers:

"headers": {
"Connection": "close",
"Content-Type": "application/x-www-form-urlencoded",
"Host": "[httpbin.org](http://httpbin.org)",
"Transfer-Encoding": "chunked",
"User-Agent": "uclient-fetch"

Transfer-Encoding "chunked" used and there is no Content-length provided

Since the post data size is known during the request, is there a way to force Content-length header to appear?

Thanks

2

you can't
this is source code of uclient-fetch, also you cannot set Content-Type

static int init_request(struct uclient *cl)
320 {
321         int rc;
322 
323         out_offset = 0;
324         out_bytes = 0;
325         out_len = 0;
326         uclient_http_set_ssl_ctx(cl, ssl_ops, ssl_ctx, verify);
327 
328         if (timeout)
329                 cl->timeout_msecs = timeout * 1000;
330 
331         rc = uclient_connect(cl);
332         if (rc)
333                 return rc;
334 
335         msg_connecting(cl);
336 
337         rc = uclient_http_set_request_type(cl, post_data ? "POST" : "GET");
338         if (rc)
339                 return rc;
340 
341         uclient_http_reset_headers(cl);
342         uclient_http_set_header(cl, "User-Agent", user_agent);
343         if (cur_resume)
344                 check_resume_offset(cl);
345 
346         if (post_data) {
347                 uclient_http_set_header(cl, "Content-Type", "application/x-www-form-urlencoded");
348                 uclient_write(cl, post_data, strlen(post_data));
349         }
350 
351         rc = uclient_request(cl);
352         if (rc)
353                 return rc;
354 
355         return 0;
356 }
3

Discussion when the code was added:
https://patchwork.ozlabs.org/project/lede/patch/CAHQM780agD+6-cCQmWuHzguHYVQiKiS-xAw+R7u=a_PLvKP3Cg@mail.gmail.com/#1382522

The uclient-fetch has inconvenient design in that place so it can send only with chunked encoding even while we already know the Content-Length.

But technically it's easy to add the CL header but I don't know if webservers can handle it correctly if CL is used with a chunked.

BusyBox httpd has a bug when sends the body with chunks as is into CGI script . So you can't use uclient-fetch with BB httpd. But uhttpd works correctly.