使用 Azure 函数 v1 的 Http 响应中不存在内容长度标头

Question

We have azure function which is running with azure v1 (.NET Framework 4.7). In http response, we are trying to set the content length but it is not flowing to client. It sets the Transfer encoding header with value as chunked. To give glimpse of how we are setting it.

var body = <some byte array data>
var response = new HttpResponseMessage();
response.Content = new ByteArrayContent(body);
response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
response.Content.Headers.ContentLength = body.Length;

I went through some online discussion and Azure/azure-functions-host#3765 There they talked about setting up,

response.Headers.TransferEncoding.Add(TransferCodingHeaderValue.Parse("identity"))

But it seems to be of no use. Would anyone faced such kind of issue before? BTW, when I ran the same code on azure function v2 (.NET Core 2.2) it works.

Update: Transfer-Encoding header we could see through packet capture using wireshark. Wireshark screenshot depicting Transfer-Encoding header even if content-length is set through code

Update-2 : This is happening for function running locally. When we publish the function on azure it does provide the content length header. Locally, I guess it (v1) uses nodejs simulator which seems to have some issue. Anyway, will update here once we find out any workaround.

Answer 1

Content-length can't be set if the Transfer-Encoding is set to be chunked . Transfer-Encoding: chunked isn't needed for progressive rendering. However, it is needed when the total content length is unknown before the first bytes are sent.

Basically, the decimal value of the content-length in OCTETs represents both the entity-length and the transfer-length. If there is some transfer-encoding, then these two lengths will be different and consequently the content-length value should be ignored.

I test with your code in function v1 without Transfer-Encoding it work well too.

So if you want to set specific content length, you could remove Transfer-Encoding .