CODEWITHSUNDEEP
c#httpclienthttp-compression
Mr J
Mr J

Reputation: 2965

Why cant I see the Content-Encoding: gzip response in my c# HttpClient response header?

I'm making a simple c# program to establish if server side compression is available/enabled on various servers. This is my request code below.

using (var client = new HttpClient())
{
    client.Timeout = new TimeSpan(0, 0, 5);
    client.DefaultRequestHeaders.Add("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8");
    client.DefaultRequestHeaders.Add("User-Agent", "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.97 Safari/537.36");
    client.DefaultRequestHeaders.Add("Accept-Encoding", "gzip, deflate, sdch, br");
    var httpClientResponse = client.GetAsync(websiteURL).Result;
    string header = httpClientResponse.Headers.GetValues("Content-Encoding").First();
}

I can see by watching the request in fiddler that compression is enabled for this request however I can't seem to extract that information from the response headers in code.

These are the full headers for request and response.

GET https://www.dobbies.com/ HTTP/1.1
Accept: text/html, application/xhtml+xml, application/xml; q=0.9, image/webp, */*; q=0.8
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.97 Safari/537.36
Accept-Encoding: gzip, deflate, sdch, br
Host: www.dobbies.com

HTTP/1.1 200 OK
Cache-Control: private
Content-Type: text/html; charset=utf-8
Content-Encoding: gzip
Vary: Accept-Encoding
Server: 
Set-Cookie: ASP.NET_SessionId=hx1rb34ottgfritgt3rciql4; path=/; secure; HttpOnly
X-Frame-Options: SAMEORIGIN
X-Content-Type-Options: nosniff
Strict-Transport-Security: max-age=31536000
X-Xss-Protection: 1; mode=block
Date: Fri, 07 Apr 2017 08:06:17 GMT
Content-Length: 16836

This is what I get when I use httpClientResponse.Headers

{
    Vary: Accept-Encoding
    X-Frame-Options: SAMEORIGIN
    X-Content-Type-Options: nosniff
    Strict-Transport-Security: max-age=31536000
    X-Xss-Protection: 1; mode=block
    Cache-Control: private
    Date: Fri, 07 Apr 2017 08:06:17 GMT
    Set-Cookie: ASP.NET_SessionId=hx1rb34ottgfritgt3rciql4; path=/; secure; HttpOnly
    Server: 
}

As you can see header of Content-Encoding: gzip is missing in the response.

Why would this header be missing? Along with others. Give me back my headers!

Upvotes: 4

Views: 4219

Answers (1)

Mr J
Mr J

Reputation: 2965

Found the problem.

The HttpResponseMessage returned by HttpClient methods has two header properties:

HttpResponseMessage.Headers is an HttpResponseHeaders with generic response headers

HttpResponseMessage.Content.Headers is an HttpContentHeaders with content-specific headers like Content-Type

Upvotes: 11

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