VB.NET

OAuth2 Token using IdentityServer4 with Client Credentials

See more OAuth2 Examples

Demonstrates how to get an OAuth2 access token using the client credential flow with IdentityServer4. VB.NET

Dim success As Boolean = False

' This example assumes the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

Dim http As New Chilkat.Http

' The first step is to fetch your IdentityServer4's discovery document
' (OpenID Connect defines a discovery mechanism, called OpenID Connect Discovery, where an OpenID server publishes its metadata at a well-known URL, 
' typically https://server.com/.well-known/openid-configuration

Dim resp As New Chilkat.HttpResponse
success = http.HttpNoBody("GET","https://localhost:5000/.well-known/openid-configuration",resp)
If (success = False) Then
    Debug.WriteLine(http.LastErrorText)
    Exit Sub
End If


If (resp.StatusCode <> 200) Then
    Debug.WriteLine("Received response status code " & resp.StatusCode)
    Debug.WriteLine("Response body containing error text or JSON:")
    Debug.WriteLine(resp.BodyStr)
    Exit Sub
End If


Dim json As New Chilkat.JsonObject
success = json.Load(resp.BodyStr)

' We have the discovery document, which contains something like this:

' You can use this online tool to generate parsing code from sample JSON: 
' Generate Parsing Code from JSON

' {
'   "issuer": "https://localhost:5000",
'   "jwks_uri": "https://localhost:5000/.well-known/openid-configuration/jwks",
'   "authorization_endpoint": "https://localhost:5000/connect/authorize",
'   "token_endpoint": "https://localhost:5000/connect/token",
'   "userinfo_endpoint": "https://localhost:5000/connect/userinfo",
'   "end_session_endpoint": "https://localhost:5000/connect/endsession",
'   "check_session_iframe": "https://localhost:5000/connect/checksession",
'   "revocation_endpoint": "https://localhost:5000/connect/revocation",
'   "introspection_endpoint": "https://localhost:5000/connect/introspect",
'   "frontchannel_logout_supported": true,
'   "frontchannel_logout_session_supported": true,
'   "backchannel_logout_supported": true,
'   "backchannel_logout_session_supported": true,
'   "scopes_supported": [
'     "openid",
'     "profile",
'     "email",
'     "MyCompany.profile",
'     "MyCompany.Identity.WebApi",
'     "MyCompany.TriHub.WebApi",
'     "offline_access"
'   ],
'   "claims_supported": [
'     "sub",
'     "updated_at",
'     "locale",
'     "zoneinfo",
'     "birthdate",
'     "gender",
'     "website",
'     "profile",
'     "preferred_username",
'     "nickname",
'     "middle_name",
'     "given_name",
'     "family_name",
'     "name",
'     "picture",
'     "email_verified",
'     "email",
'     "userId",
'     "groups",
'     "fullname"
'   ],
'   "grant_types_supported": [
'     "authorization_code",
'     "client_credentials",
'     "refresh_token",
'     "implicit",
'     "password"
'   ],
'   "response_types_supported": [
'     "code",
'     "token",
'     "id_token",
'     "id_token token",
'     "code id_token",
'     "code token",
'     "code id_token token"
'   ],
'   "response_modes_supported": [
'     "form_post",
'     "query",
'     "fragment"
'   ],
'   "token_endpoint_auth_methods_supported": [
'     "client_secret_basic",
'     "client_secret_post"
'   ],
'   "subject_types_supported": [
'     "public"
'   ],
'   "id_token_signing_alg_values_supported": [
'     "RS256"
'   ],
'   "code_challenge_methods_supported": [
'     "plain",
'     "S256"
'   ]
' }
' 

' The next steps are to (1) get the token_endpoint,
' and (2) verify that the client_credentials grant type is supported.

Dim tokenEndpoint As String = json.StringOf("token_endpoint")

Dim grantTypes As Chilkat.JsonArray = json.ArrayOf("grant_types_supported")
Dim clientCredentialsIdx As Integer = grantTypes.FindString("client_credentials",True)


' If clientCredentialsIdx is less then zero (-1) then the "client_credentials" string was not found.
If (clientCredentialsIdx < 0) Then
    Debug.WriteLine("The client credentials grant type is not supported.")
    Exit Sub
End If


' Request the access token using our Client ID and Client Secret.
' We're going to duplicate this CURL statement:

' curl --request POST \
'   --url '<tokenEndpoint>' \
'   --header 'content-type: application/x-www-form-urlencoded' \
'   --data 'grant_type=client_credentials&client_id=CLIENT_ID&client_secret=CLIENT_SECRET'

Dim req As New Chilkat.HttpRequest
req.HttpVerb = "POST"
req.ContentType = "application/x-www-form-urlencoded"

req.AddParam("grant_type","client_credentials")
req.AddParam("client_id","CLIENT_ID")
req.AddParam("client_secret","CLIENT_SECRET")req.HttpVerb = "POST"

success = http.HttpReq(tokenEndpoint,req,resp)
If (success = False) Then
    Debug.WriteLine(http.LastErrorText)
    Exit Sub
End If


' Make sure we got a 200 response status code, otherwise it's an error.
If (resp.StatusCode <> 200) Then
    Debug.WriteLine("POST to token endpoint failed.")
    Debug.WriteLine("Received response status code " & resp.StatusCode)
    Debug.WriteLine("Response body containing error text or JSON:")
    Debug.WriteLine(resp.BodyStr)
    Exit Sub
End If


success = json.Load(resp.BodyStr)

' Our JSON response should contain this:
' {
'   "access_token":"eyJz93a...k4laUWw",
'   "token_type":"Bearer",
'   "expires_in":86400
' }

' Get the access token:
Dim accessToken As String = json.StringOf("access_token")

' The access token is what gets added to "Authorization: Bearer <access_token>"
' for the subsequent REST API calls..