Unicode C

Facebook OAuth2 Access Token

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Demonstrates how to get a Facebook OAuth2 access token from a desktop application or script. Unicode C

#include <C_CkOAuth2W.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkOAuth2W oauth2;
    const wchar_t *url;
    int numMsWaited;

    success = FALSE;

    // To further clarify, see OAuth 2.0 Authorization Flow

    oauth2 = CkOAuth2W_Create();

    // This should match the Site URL configured for your Facebook APP, such as "http://localhost:3017/"
    CkOAuth2W_putListenPort(oauth2,3017);

    CkOAuth2W_putAuthorizationEndpoint(oauth2,L"https://www.facebook.com/dialog/oauth");
    CkOAuth2W_putTokenEndpoint(oauth2,L"https://graph.facebook.com/oauth/access_token");

    // Replace this with your actual App ID
    CkOAuth2W_putClientId(oauth2,L"APP_ID");

    // Set the Scope to a comma-separated list of permissions the app wishes to request.
    // See https://developers.facebook.com/docs/facebook-login/permissions/ for a full list of permissions.
    CkOAuth2W_putScope(oauth2,L"public_profile,user_friends,email,user_posts,user_likes,user_photos");

    // This is for Require Proof Key for Code Exchange (PKCE)
    // See OAuth2 PKCE Explained
    CkOAuth2W_putCodeChallenge(oauth2,TRUE);
    CkOAuth2W_putCodeChallengeMethod(oauth2,L"S256");

    // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    url = CkOAuth2W_startAuth(oauth2);
    if (CkOAuth2W_getLastMethodSuccess(oauth2) != TRUE) {
        wprintf(L"%s\n",CkOAuth2W_lastErrorText(oauth2));
        CkOAuth2W_Dispose(oauth2);
        return;
    }

    wprintf(L"url = %s\n",url);

    // Launch the default browser on the system and navigate to the url.
    // The LaunchBrowser method was added in Chilkat v10.1.2.
    success = CkOAuth2W_LaunchBrowser(oauth2,url);
    if (success == FALSE) {
        wprintf(L"%s\n",CkOAuth2W_lastErrorText(oauth2));
        CkOAuth2W_Dispose(oauth2);
        return;
    }

    // Wait for the user to approve or deny authorization in the browser.
    numMsWaited = 0;
    while ((numMsWaited < 90000) && (CkOAuth2W_getAuthFlowState(oauth2) < 3)) {
        CkOAuth2W_SleepMs(oauth2,100);
        numMsWaited = numMsWaited + 100;
    }

    // If the browser does not respond within the specified time, AuthFlowState will be:
    // 
    // 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
    // 2: Waiting for Final Response – The thread is awaiting the final access token response.
    // In either case, cancel the background task initiated by StartAuth.

    if (CkOAuth2W_getAuthFlowState(oauth2) < 3) {
        CkOAuth2W_Cancel(oauth2);
        wprintf(L"No response from the browser!\n");
        CkOAuth2W_Dispose(oauth2);
        return;
    }

    // Check AuthFlowState to determine if authorization was granted, denied, or failed:
    // 
    // 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
    // 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
    // 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

    if (CkOAuth2W_getAuthFlowState(oauth2) == 5) {
        wprintf(L"OAuth2 failed to complete.\n");
        wprintf(L"%s\n",CkOAuth2W_failureInfo(oauth2));
        CkOAuth2W_Dispose(oauth2);
        return;
    }

    if (CkOAuth2W_getAuthFlowState(oauth2) == 4) {
        wprintf(L"OAuth2 authorization was denied.\n");
        wprintf(L"%s\n",CkOAuth2W_accessTokenResponse(oauth2));
        CkOAuth2W_Dispose(oauth2);
        return;
    }

    if (CkOAuth2W_getAuthFlowState(oauth2) != 3) {
        wprintf(L"Unexpected AuthFlowState:%d\n",CkOAuth2W_getAuthFlowState(oauth2));
        CkOAuth2W_Dispose(oauth2);
        return;
    }

    wprintf(L"OAuth2 authorization granted!\n");
    wprintf(L"Access Token = %s\n",CkOAuth2W_accessToken(oauth2));


    CkOAuth2W_Dispose(oauth2);

    }