(PowerBuilder) OAuth2 Token using IdentityServer4 with Client Credentials

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

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

integer li_rc
oleobject loo_Http
oleobject loo_Resp
oleobject loo_Json
integer li_Success
string ls_TokenEndpoint
oleobject loo_GrantTypes
integer li_ClientCredentialsIdx
oleobject loo_Req
string ls_AccessToken

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

loo_Http = create oleobject
li_rc = loo_Http.ConnectToNewObject("Chilkat_9_5_0.Http")
if li_rc < 0 then
    destroy loo_Http
    MessageBox("Error","Connecting to COM object failed")
    return
end if

// 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

loo_Resp = loo_Http.QuickRequest("GET","https://localhost:5000/.well-known/openid-configuration")
if loo_Http.LastMethodSuccess <> 1 then
    Write-Debug loo_Http.LastErrorText
    destroy loo_Http
    return
end if

if loo_Resp.StatusCode <> 200 then
    Write-Debug "Received response status code " + string(loo_Resp.StatusCode)
    Write-Debug "Response body containing error text or JSON:"
    Write-Debug loo_Resp.BodyStr
    destroy loo_Resp
    destroy loo_Http
    return
end if

loo_Json = create oleobject
li_rc = loo_Json.ConnectToNewObject("Chilkat_9_5_0.JsonObject")

li_Success = loo_Json.Load(loo_Resp.BodyStr)
destroy loo_Resp

// 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.

ls_TokenEndpoint = loo_Json.StringOf("token_endpoint")

loo_GrantTypes = loo_Json.ArrayOf("grant_types_supported")
li_ClientCredentialsIdx = loo_GrantTypes.FindString("client_credentials",1)
destroy loo_GrantTypes

// If clientCredentialsIdx is less then zero (-1) then the "client_credentials" string was not found.
if li_ClientCredentialsIdx < 0 then
    Write-Debug "The client credentials grant type is not supported."
    destroy loo_Http
    destroy loo_Json
    return
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'

loo_Req = create oleobject
li_rc = loo_Req.ConnectToNewObject("Chilkat_9_5_0.HttpRequest")

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

loo_Resp = loo_Http.PostUrlEncoded(ls_TokenEndpoint,loo_Req)
if loo_Http.LastMethodSuccess = 0 then
    Write-Debug loo_Http.LastErrorText
    destroy loo_Http
    destroy loo_Json
    destroy loo_Req
    return
end if

// Make sure we got a 200 response status code, otherwise it's an error.
if loo_Resp.StatusCode <> 200 then
    Write-Debug "POST to token endpoint failed."
    Write-Debug "Received response status code " + string(loo_Resp.StatusCode)
    Write-Debug "Response body containing error text or JSON:"
    Write-Debug loo_Resp.BodyStr
    destroy loo_Resp
    destroy loo_Http
    destroy loo_Json
    destroy loo_Req
    return
end if

li_Success = loo_Json.Load(loo_Resp.BodyStr)
destroy loo_Resp

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

// Get the access token:
ls_AccessToken = loo_Json.StringOf("access_token")

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


destroy loo_Http
destroy loo_Json
destroy loo_Req