Adding HttpClient headers generates a FormatException with some values - c#

This occurred within the context of coding against Google Cloud Messaging, but applies elsewhere.
Consider the following:
var http = new HttpClient();
http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("key=XXX");
and
var http = new HttpClient();
http.DefaultRequestHeaders.Add("Authorization", "key=XXX");
both of which generate a FormatException:
System.FormatException : The format of value key=XXX' is invalid.
The solution is to remove the equals sign.
Digging into reflector shows there is oodles of validation and parsing code that runs when adding a a new header value. Why is all this necessary? Shouldn't this client just be getting out of our way?
How do you escape the equals sign so that adding this value succeeds?

Not sure if still relevant, but I recently ran into this same issue and was able to solve it by calling a different method to add the header information:
var http = new HttpClient();
http.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", "key=XXX");

To your "why is all this (parsing and validation) necessary" question, the answer is: it is defined in the HTTP standard.
In HTTP/1.1 and RFC2617, the value an authentication header (such as WWW-Authenticate and Authorization) has two parts: a scheme part, and a parameter part.
For HTTP Basic Authentication, the scheme is "Basic", and the parameter may be something like "QWxhZGRpbjpvcGVuIHNlc2FtZQ==", so the whole header becomes:
Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==
That's why your "key=XXX" doesn't pass validation, because it lacks a scheme part.

I ran into this error and stumbled on to this post when I added a space to the end of an Authorization header.
this.bearerAuthHttpClient.DefaultRequestHeaders.Add("Authorization ", $"Bearer {token}");
You can see the offending " " after Authorization.
It took me about 15 min before I saw my typo...

I got around this exception (my FormatException caused by commas in the value) by setting the Authorization header in the following way:
var authenticationHeaderValue = new AuthenticationHeaderValue("some scheme", "some value");
client.DefaultRequestHeaders.Authorization = authenticationHeaderValue;

I've been going through a few questions this morning while dealing with an external API that doesn't follow the HTTP spec to the letter.
As part of my posting, they want the Content-Type and Content-Disposition, which cannot be added to the HttpClient object. To add those headers, you need to create an HttpRequestMessage. On there, you need to add the headers to the Content property.
private HttpRequestMessage GetPostMessage(string uri, string contentType,
string fileName, Stream content)
{
var request = new HttpRequestMessage
{
Content = new StreamContent(content),
RequestUri = new Uri(uri),
Method = HttpMethod.Post
};
// contentType = "video/mp4"
request.Content.Headers.ContentType = new MediaTypeHeaderValue(contentType);
//Need TryAddWithoutValidation because of the equals sign in the value.
request.Content
.Headers
.TryAddWithoutValidation("Content-Disposition",
$"attachment; filename=\"{Path.GetFileName(fileName)}\"");
// If there is no equals sign in your content disposition, this will work:
// request.Content.Headers.ContentDisposition =
// new ContentDispositionHeaderValue($"attachment; \"{Path.GetFileName(fileName)}\"");
return request;
}

In my case I am generating ETags string values from a byte[] RowVersion SQL field.
So I need to add wrap the generated. i.e. AAAAAAAAF5s= string inside " as follows...
var eTag = department.RowVersion.ToETagString();
httpClient.DefaultRequestHeaders.Add(Microsoft.Net.Http.Headers.HeaderNames.IfMatch, $"\"{eTag}\"")
public class DepartmentForHandleDto
{
public string Name { get; set; }
public string GroupName { get; set; }
public byte[] RowVersion { get; set; }
}
public static class ByteArrayExtensions
{
public static string ToETagString(this byte[] byteArray)
{
return Convert.ToBase64String(byteArray != null && byteArray.Length > 0 ? byteArray : new byte[8]);
}
}

Related

How to set content-md5 header in GET method using HttpClient?

I have the following code to set content-md5 in my GET method request using HttpClient
httpClient.DefaultRequestHeaders.TryAddWithoutValidation("content-md5", "value");
I cannot use HttpRequestMessage content to set it because it's not a POST method. When using Postman it works like a charm but fails when using HttpClient.GetAsync.
Client request a hmac to the server as follows
{
"content_to_hash": "my content"
}
The server will give response like this
{
"content_md5": "88af7ceab9fdafb76xxxxx",
"date": "Sat, 02 May 2020 00:13:16 +0700",
"hmac_value": "WfHgFyT792IENmK8Mqz9LysmP8ftOP00qA="
}
Now I have to access a GET request using that hmac where it's the problem because I cannot set in httpClient GET request header.
Here's the image
From reading the HttpClient and related source code, there's no way you can get around this and add the header to the actual request object headers. There is an internal list of invalid headers, which includes any Content-* headers. It has to be on a content object.
Therefore, my suggest solution is to create your own content object:
public class NoContentMd5 : HttpContent
{
protected override Task SerializeToStreamAsync(Stream stream, TransportContext context)
{
return Task.CompletedTask;
}
protected override bool TryComputeLength(out long length)
{
length = 0;
return false;
}
public NoContentMd5(byte[] contentMd5)
{
this.Headers.ContentMD5 = contentMd5;
}
public NoContentMd5(string contentMd5)
{
this.Headers.TryAddWithoutValidation("Content-MD5", contentMd5);
}
}
This will add the Content-MD5 header with a value of your choosing, but the request won't contain a body.
The next problem you'll encounter is that you're trying to make a GET request with content, which isn't supported by the helper client.GetAsync(...) method. You'll have to make your own request object and use client.SendAsync(...) instead:
HttpClient client = new HttpClient();
var request = new HttpRequestMessage(HttpMethod.Get, "https://localhost/my/test/uri");
request.Content = new NoContentMd5("d41d8cd98f00b204e9800998ecf8427e ");
var result = await client.SendAsync(request);
Note that if you have your Content-MD5 hash as bytes, I've also added a constructor to NoContentMd5 for byte[] too.
The only potential issue with this is that it includes a Content-Length: 0 header. Hopefully that's OK with the API you're working with.
There's an alternative solution described in this answer to question with a similar issue. I'd argue against using it since is vulnerable to changes in the implementation details of HttpRequestHeaders (because it uses reflection, so if MS change the code, it might break) .
Aside from the fact that it's not considered good practice to send a body with GET request (see HTTP GET with request body), you can try this:
using (var content = new StringContent(string.Empty))
using (var request = new HttpRequestMessage
{
Method = HttpMethod.Get,
RequestUri = new Uri("http://localhost"),
Content = content
})
{
request.Headers.TryAddWithoutValidation("content-md5", "value");;
using (var response = await httpClient.SendAsync(request))
{
response.EnsureSuccessStatusCode();
}
}
UPDATE:
The proper way would be to set the ContentMD5 property on the HttpContentHeaders, for example:
content.Headers.ContentMD5 = Convert.FromBase64String(hashString);
But as you pointed out in the comments, trying to send content in a GET request causes an error.

Adding Comment to Fortify Issue via REST API results in Content Encoding Error

I'm trying to add a comment to an issue inside Fortify. When I POST what I think is the correct JSON, I receive the response "{"message":"Content was incorrectly formatted (expected application/json; charset=utf-8).","responseCode":400,"errorCode":-20209}"
However, if I use Fiddler to examine the message I'm POSTing and receiving the appropriate headers appear to be in place. What secondary issue could be causing this exception to be thrown?
Fortify v18.10.0187
.NET v4.6.2
Newtonsoft.Json v9.0.0
public static string PostCommentIssue(FortifyComment fc)
{
var content = JsonConvert.SerializeObject(fc);
var postUri = String.Format(Configuration.FortifyCommentsUri, fc.data.issueId);
return WebServiceHelper.PostMessage(postUri, content);
}
public static string PostMessage(string url, string content)
{
HttpRequestMessage requestMessage = new HttpRequestMessage(HttpMethod.Post, url);
requestMessage.Headers.Add("Authorization", Configuration.FortifyAuthorization.ToHeader());
requestMessage.Content = new StringContent(content, Encoding.UTF8, JsonMediaTypeFormatter.DefaultMediaType.MediaType);
HttpResponseMessage hrm = HttpClient.SendAsync(requestMessage).Result;
hrm.EnsureSuccessStatusCode();
HttpContent hc = hrm.Content;
return hc.ReadAsStringAsync().Result;
}
FortifyComment is just an object with the basic elements of a comment in it. It's based on the Fortify response given on a query (thus the inner data element).
Using
FortifyComment fc = new FortifyComment();
fc.data.issueId = defect.id;
fc.data.comment = String.Format("TFS #{0}.", tfsNumber);
FortifyHelper.PostCommentIssue(fc);
I receive the 400 error. Screenshot of Fiddler intercept:

RestSharp "Error getting response stream (ReadAsync): ReceiveFailure Value cannot be null. Parameter name: src"

Hello all am trying to do a login to my xamarin api using RestSharp, the API ought to return status code 200 OK if the authentication works and status code 415 if the authentication fails(wrong password) and other codes depending on what the case scenario, but instead i get a status code 0 on all other case asides when the authentication pass(status code 200 ok), the source code below is how i implement
//payload am sending to the api
RequestPayload res = new RequestPayload();
res.appid = appid;
res.data = data;
res.method = "Login";
//convert to json object
var MySerializedObject = JsonConvert.SerializeObject(res);
string APIUrl = ""http://142.168.20.15:8021/RouteTask";
//create client
RestClient client = new RestClient(APIUrl);
//create request
RestRequest request = new RestRequest(Method.POST);
// set request headeer
request.AddHeader("Content-Type", "application/x-www-form-urlencoded");
//request.AddJsonBody(MySerializedObject); --i have also tried this
request.AddParameter("application/json", MySerializedObject, ParameterType.RequestBody);
request.JsonSerializer.ContentType = "application/json; charset=utf-8";
request.AddParameter("RequestSource", "Web", "application/json", ParameterType.QueryString);
client.Timeout = 2000000;
var response = client.Execute(request); // where the issue appears
//RestResponse response = client.Execute(request); // i have tried this
//IRestResponse response = client.Execute(request); // i have tried this
if (response.IsSuccessful)
{
//use response data
}
on all scenerio it comes back with a StatusCode: 0, Content-Type: , Content-Length: 0) and errorMessage
"Error getting response stream (ReadAsync): ReceiveFailure Value
cannot be null. Parameter name: src"
screenshot below indicate when the api call fails
Response receieved when the authentication is valid
I was finally able to find a workaround for this. Bear with the long-winded response.
The tags mention Xamarin, which is what I am working in as well - specifically with iOS. I think it may actually be a bug with Mono, but I didn't take it that far to confirm.
The problem lies with the default way of copying the response buffer. In the RestSharp code, this is done by an extension method in MiscExtensions.cs called ReadAsBytes. It appears that with certain response buffers, the call to the Stream.Read method is failing. When this happens, the exception causes RestSharp to "shortcut" the rest of the processing on the response, hence the status code never gets filled in since it happens after the call to ReadAsBytes.
The good news is RestSharp does give a way to replace this call to ReadAsBytes with one of your own. This is done via the ResponseWriter property on the IRestRequest object. If it has a function defined, it will bypass the ReadAsBytes call and call the function you gave it instead. The problem is, this is defined as an Action and you don't get a copy of the full response object, so it's somewhat useless. Instead you have to use the AdvancedResponseWriter property. This one includes both the response object and the response stream. But you still have to set the ResponseWriter property or it won't bypass the default handler and you'll still get the error.
Ok, so how do you make this work? I ended up implementing it as a wrapper to RestClient so I wouldn't have to implement the code all over the place. Here's the basic setup:
public class MyRestClient : RestClient
{
public MyRestClient(string baseUrl) : base(baseUrl)
{ }
public override IRestResponse Execute(IRestRequest request)
{
request.ResponseWriter = s => { };
request.AdvancedResponseWriter = (input, response) => response.RawBytes = ReadAsBytes(input);
return base.Execute(request);
}
private static byte[] ReadAsBytes(Stream input)
{
var buffer = new byte[16 * 1024];
using (var ms = new MemoryStream())
{
int read;
try
{
while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
{ ms.Write(buffer, 0, read); }
return ms.ToArray();
}
catch (WebException ex)
{ return Encoding.UTF8.GetBytes(ex.Message); }
};
}
}
The ReadAsBytes method is actually just a copy/paste of the RestSharp ReadAsBytes method with the addition of a try/catch. If it fails, it returns the exception reason in to the response buffer. This may or may not be what you want, so modify as needed. You may also need to override other methods for Execute, but in my case this is the only one we're using so it was enough.
So far this seems to be doing the trick for me. Perhaps if someone got ambitious they could trace it all the way in to Mono to try and see what it doesn't like about the stream, but I don't have the time for it at the moment.
Good luck!
OK so after toying around with RestSharp for a bit, i realize just as #steve_In_Co mentioned earlier there were compatibility issues with MONO (we presume this is a bug) so i did it in a basic way using the .Net HTTP library and it works for me, so in case someone is still looking for a way out, find the working .net http implementation code below.
//payload am sending to the api
RequestPayload res = new RequestPayload();
res.appid = appid;
res.data = data;
res.method = "Login";
//convert to json object
var MySerializedObject = JsonConvert.SerializeObject(res);
string APIUrl = ""http://142.168.20.15:8021/RouteTask";
//create basic .net http client
HttpClient client = new HttpClient();
client.BaseAddress = new Uri(APIUrl);
// this was required in the header of my request,
// you may not need this, or you may need to adjust parameter
//("RequestSource","Web") or you own custom headers
client.DefaultRequestHeaders.Add("RequestSource", "Web");
// this class is custom, you can leave it out
connectionService = new ConnectionService();
//check for internet connection on users device before making the call
if (connectionService.IsConnected)
{
//make the call to the api
HttpResponseMessage response = await
client.PostAsJsonAsync(ApiConstants.APIDefault, res);
if (response.IsSuccessStatusCode)
{
string o = response.Content.ReadAsStringAsync().Result;
dynamic payload = JsonConvert.DeserializeObject(o);
string msg = payload["valMessage"];
resp.a = true;
resp.msg = payload["responseDescription"];
}
else
{
string o = response.Content.ReadAsStringAsync().Result;
dynamic payload = JsonConvert.DeserializeObject(o);
resp.a = false;
resp.msg = payload["response"];
}
}

How to post json into HTTP server

I was wondering how can I make a post from a json to an http server.
The code I'm using to do json is as follows:
pedro product = new pedro();
product.FirtsName = "Ola";
product.ID = 1;
product.idade= 10;
string json = JsonConvert.SerializeObject(product);
And this is the pedro class:
public class pedro
{
public int ID { get; set; }
public string FirtsName { get; set; }
public int idade { get; set; }
}
With WebApi, you can use something like this:
string url = "http://url.of.server/";
Pedro product = new Pedro();
product.FirtsName = "Ola";
product.ID = 1;
product.Idade = 10;
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(url);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage response = client.PostAsJsonAsync(url, product).Result;
if (response.IsSuccessStatusCode)
{
// do something
}
}
If you're not using WepApi there are many similar methods, for instance: https://stackoverflow.com/a/39414248/7489072
Don't Base64 encode the body of your post, as suggested in the comments, unless you absolutely must / want to post binary files AND have control over the receiving webserver. Webservers in 99% of the cases expect a plain text body.
If you need to post characters outside the ASCII range, use the correct HTTP headers to specify a Unicode body load.
Update 1 (headers):
The HttpClient class has property DefaultRequestHeaders that can be used to set common request headers, such as AcceptEncoding. If you need a more fine grained control of the content headers, use .PostAsync(string uri, HttpContent content) in stead of .PostAsJsonAsync (that just sets some default headers for Json content)
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(url);
client.DefaultRequestHeaders.Accept.Clear();
client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
string stringFromObject = JsonConvert.SerializeObject(product);
HttpContent content = new StringContent(stringFromObject, Encoding.UTF8, "application/json");
content.Headers.Add("YourCustomHeader", "YourParameter");
HttpResponseMessage response = client.PostAsync(url, content).Result;
if (response.IsSuccessStatusCode)
{
// do something
}
}
Update 2 (encoding):
To elaborate more on the encoding comments: of course you should escape quotes and the likes. But this is part of the Json standard and should be handled by common encoders / decoders. On top of that, you can use any further encoding for the properties of your serialized object. For instance HTML-encoding on strings and Base64 on binary properties. As long as you know the webserver receiving it will decode it properly.
{
"id": 3,
"title": "Decode this",
"description": "this is < HTML encoded >",
"profileImgBase64": "Nzg5MzQ4IHdleWhmQVMmKihFJiphc3R5WUdkdCphc14qVHlpZg0K"
}
So encode individual properties, but don't encode the whole Json payload, as you would have to decode it at the beginning of the receiving pipeline and it's just not something webservers will understand.

'UTF8' is not a supported encoding name

So I'm just playing around with Spotify's Web API and I'm trying to access my top played tracks. Although I've encountered a problem I've been trying to solve for a couple of hours now but I can't find an answer.
When I try to deserialize my response, I get the follwing error:
'UTF8' is not a supported encoding name. For information on defining a custom encoding, see the documentation for the Encoding.RegisterProvider method.
Parameter name: name
The character set provided in ContentType is invalid. Cannot read content as string using an invalid character set.
The ContentType is application/json; charset=UTF8
Any ideas?
Here's my request code:
private static HttpClient GetHttpClient()
{
HttpClientHandler handler = new HttpClientHandler() {
AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate
};
var httpClient = new HttpClient(handler);
httpClient.DefaultRequestHeaders.Add("Accept", "application/json");
return httpClient;
}
public async Task<SearchArtistResponse> GetSelfTopAsync(string type, string userName)
{
var httpClient = GetHttpClient();
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", GetAccessToken(userName));
var sb = new StringBuilder();
sb.Append(ApiUrl);
sb.Append($"/me/top/{type}");
var query = sb.ToString();
var response = await httpClient.GetAsync(query);
var spotifyResponse = JsonConvert.DeserializeObject<SearchArtistResponse>(await response.Content.ReadAsStringAsync());
return spotifyResponse;
}
Are you using .net core?
You will need to add the following code to make the encodings available in .NET desktop available in your environment:
System.Text.EncodingProvider provider = System.Text.CodePagesEncodingProvider.Instance;
Encoding.RegisterProvider(provider);
More info on CodePagesEncodingProvider.Instance can be found here.
The problem should be a validation of response header Content-Type ,that occur when you call ReadAsStringAsync(), if you call ReadAsByteArrayAsync() instead and parse to string
(System.Text.Encoding.UTF8.GetString())
that will gonna work!!!
I had a same problem while I was trying to get an answer from my API which is built in PHP using C# service. I could fix the issue by changing "charset=UTF8" to "charset=\"UTF-8\"" on the PHP side(the api that sends result to the C# service). Hope this helps someone.

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