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C++

OAuth2 Token using IdentityServer4 with Client Credentials

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

Chilkat C++ Downloads

C++
#include <CkHttp.h>
#include <CkHttpResponse.h>
#include <CkJsonObject.h>
#include <CkJsonArray.h>
#include <CkHttpRequest.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    CkHttp 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

    CkHttpResponse resp;
    success = http.HttpNoBody("GET","https://localhost:5000/.well-known/openid-configuration",resp);
    if (success == false) {
        std::cout << http.lastErrorText() << "\r\n";
        return;
    }

    if (resp.get_StatusCode() != 200) {
        std::cout << "Received response status code " << resp.get_StatusCode() << "\r\n";
        std::cout << "Response body containing error text or JSON:" << "\r\n";
        std::cout << resp.bodyStr() << "\r\n";
        return;
    }

    CkJsonObject json;
    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.

    const char *tokenEndpoint = json.stringOf("token_endpoint");

    CkJsonArray *grantTypes = json.ArrayOf("grant_types_supported");
    int clientCredentialsIdx = grantTypes->FindString("client_credentials",true);
    delete grantTypes;

    //  If clientCredentialsIdx is less then zero (-1) then the "client_credentials" string was not found.
    if (clientCredentialsIdx < 0) {
        std::cout << "The client credentials grant type is not supported." << "\r\n";
        return;
    }

    //  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'

    CkHttpRequest req;
    req.put_HttpVerb("POST");
    req.put_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.put_HttpVerb("POST");

    success = http.HttpReq(tokenEndpoint,req,resp);
    if (success == false) {
        std::cout << http.lastErrorText() << "\r\n";
        return;
    }

    //  Make sure we got a 200 response status code, otherwise it's an error.
    if (resp.get_StatusCode() != 200) {
        std::cout << "POST to token endpoint failed." << "\r\n";
        std::cout << "Received response status code " << resp.get_StatusCode() << "\r\n";
        std::cout << "Response body containing error text or JSON:" << "\r\n";
        std::cout << resp.bodyStr() << "\r\n";
        return;
    }

    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:
    const char *accessToken = json.stringOf("access_token");

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