Content-Length is not being proxied

[montenegrodr]

Running the simplest example copied from Library Usage - the same exact code. With this configuration.json:

{
  "version": 2,
  "name": "My lovely gateway",
  "port": 8080,
  "host": [
    "http://127.0.0.1:8080"
  ],
  "endpoints": [
    {
      "endpoint": "/",
      "method": "POST",
      "backend": [
        {
          "host": [
            "http://127.0.0.1:8000"
          ],
          "encoding": "json"
        }
      ],
      "headers_to_pass": [
        "Content-Length",
        "Content-Type",
        "Accept",
        "Host",
        "User-Agent"
      ]
    }
  ]
}

I am not getting Content-Length on my CherryPy service. It's possible to reproduce with this request:

curl --fail -X POST -H 'Content-Type: application/json' -H 'Content-Length: 22' -H 'Accept: json' -d '{"text": "0000000000"}' 'http://localhost:8080' 

All other headers and content are proxied correctly. The problem is only with Content-Length.

[kpacha]

hi @montenegrodr , welcome to the KrakenD community.

The behaviour is related with the net/http package:

For client requests, certain headers such as Content-Length and Connection are automatically written when needed and values in Header may be ignored.

https://golang.org/src/net/http/request.go?s=#L157

All the layers in the pipe do propagate all the defined headers, but the internal newTransferWriter function of the net/http package assigns the value t.ContentLength = rr.outgoingLength() and does not propagate the received Content-Length header.

Following the white rabbit into the hole, I found the NewHTTPProxyDetailed middleware is not defining the requestToBackend.ContentLength property because it always sends chunked requests.

Without reading the request body before forwarding it, the only way I can see to allow the propagation of the Content-Length header is to include some 'nasty hack', such as parsing the received header and if it contains an integer, setting the requestToBackend.ContentLength property... allowing some other weird situations if the clients do not send the proper value for the header.

Any ideas?

[montenegrodr]

Thanks for your prompt reply @kpacha.

Could you point me to an example showing how can I intercept the request and modify the header before forward it?

[kpacha]

here is an example of my dumb proposal: b9093c0

reading the actual request.Body would require some extra calculations and allocations, but the required code would be placed there too

[montenegrodr]

In the end I decided to change my cherryPy service. Thanks anyway for the effort here. Leaving the issue open to you to decided to close or not.

[kpacha]

fixed, thanks!

[github-actions]

This issue was marked as resolved a long time ago and now has been automatically locked as there has not been any recent activity after it. You can still open a new issue and reference this link.