(.NET Core C#) Xero OAuth1 Authorization (3-legged)

Demonstrates 3-legged OAuth1 authorization for Xero

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string consumerKey = "XERO_CONSUMER_KEY";
string consumerSecret = "XERO_CONSUMER_SECRET";

string requestTokenUrl = "https://api.xero.com/oauth/RequestToken";
string authorizeUrl = "https://api.xero.com/oauth/Authorize";
string accessTokenUrl = "https://api.xero.com/oauth/AccessToken";

// The port number is picked at random. It's some unused port that won't likely conflict with anything else..
string callbackUrl = "http://localhost:3017/";
int callbackLocalPort = 3017;

// The 1st step in 3-legged OAuth1.0a is to send a POST to the request token URL to obtain an OAuth Request Token
Chilkat.Http http = new Chilkat.Http();
bool success;

http.OAuth1 = true;
http.OAuthConsumerKey = consumerKey;
http.OAuthConsumerSecret = consumerSecret;
http.OAuthCallback = callbackUrl;

Chilkat.HttpRequest req = new Chilkat.HttpRequest();
Chilkat.HttpResponse resp = http.PostUrlEncoded(requestTokenUrl,req);
if (http.LastMethodSuccess != true) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

// If successful, the resp.BodyStr contains something like this:  
// oauth_token=-Wa_KwAAAAAAxfEPAAABV8Qar4Q&oauth_token_secret=OfHY4tZBX2HK4f7yIw76WYdvnl99MVGB&oauth_callback_confirmed=true
Debug.WriteLine(resp.BodyStr);

Chilkat.Hashtable hashTab = new Chilkat.Hashtable();
hashTab.AddQueryParams(resp.BodyStr);

string requestToken = hashTab.LookupStr("oauth_token");
string requestTokenSecret = hashTab.LookupStr("oauth_token_secret");
http.OAuthTokenSecret = requestTokenSecret;

Debug.WriteLine("oauth_token = " + requestToken);
Debug.WriteLine("oauth_token_secret = " + requestTokenSecret);

// ---------------------------------------------------------------------------
// The next step is to form a URL to send to the authorizeUrl
// This is an HTTP GET that we load into a popup browser.
Chilkat.StringBuilder sbUrlForBrowser = new Chilkat.StringBuilder();
sbUrlForBrowser.Append(authorizeUrl);
sbUrlForBrowser.Append("?oauth_token=");
sbUrlForBrowser.Append(requestToken);
string urlForBrowser = sbUrlForBrowser.GetAsString();

// When the urlForBrowser is loaded into a browser, the response from Xero will redirect back to localhost:3017
// We'll need to start a socket that is listening on port 3017 for the callback from the browser.
Chilkat.Socket listenSock = new Chilkat.Socket();

int backLog = 5;
success = listenSock.BindAndListen(callbackLocalPort,backLog);
if (success != true) {
    Debug.WriteLine(listenSock.LastErrorText);
    return;
}

// Wait for the browser's connection in a background thread.
// (We'll send load the URL into the browser following this..)
// Wait a max of 60 seconds before giving up.
int maxWaitMs = 60000;
Chilkat.Task task = listenSock.AcceptNextConnectionAsync(maxWaitMs);
task.Run();

//  At this point, your application should load the URL in a browser.
//  For example,
//  in C#:  System.Diagnostics.Process.Start(urlForBrowser);
//  in Java: Desktop.getDesktop().browse(new URI(urlForBrowser));
//  in VBScript: Set wsh=WScript.CreateObject("WScript.Shell")
//               wsh.Run urlForBrowser
// in Xojo: ShowURL(url)  (see http://docs.xojo.com/index.php/ShowURL)
// in Dataflex: Runprogram Background "c:\Program Files\Internet Explorer\iexplore.exe" sUrl        
//  The Xero account owner would interactively accept or deny the authorization request.

//  Add the code to load the url in a web browser here...
//  Add the code to load the url in a web browser here...
//  Add the code to load the url in a web browser here...
// System.Diagnostics.Process.Start(urlForBrowser);

// Wait for the listenSock's task to complete.
success = task.Wait(maxWaitMs);
if (!success || (task.StatusInt != 7) || (task.TaskSuccess != true)) {
    if (!success) {
        // The task.LastErrorText applies to the Wait method call.
        Debug.WriteLine(task.LastErrorText);
    }
    else {
        // The ResultErrorText applies to the underlying task method call (i.e. the AcceptNextConnection)
        Debug.WriteLine(task.Status);
        Debug.WriteLine(task.ResultErrorText);
    }

    return;
}

// If we get to this point, the connection from the browser arrived and was accepted.

// We no longer need the listen socket...
// Stop listening on port 3017.
listenSock.Close(10);

// First get the connected socket.
Chilkat.Socket sock = new Chilkat.Socket();
sock.LoadTaskResult(task);

// Read the start line of the request..
string startLine = sock.ReceiveUntilMatch("\r\n");
if (sock.LastMethodSuccess != true) {
    Debug.WriteLine(sock.LastErrorText);
    return;
}

// Read the request header.
string requestHeader = sock.ReceiveUntilMatch("\r\n\r\n");
if (sock.LastMethodSuccess != true) {
    Debug.WriteLine(sock.LastErrorText);
    return;
}

// The browser SHOULD be sending us a GET request, and therefore there is no body to the request.
// Once the request header is received, we have all of it.
// We can now send our HTTP response.
Chilkat.StringBuilder sbResponseHtml = new Chilkat.StringBuilder();
sbResponseHtml.Append("<html><body><p>Chilkat thanks you!</b></body</html>");

Chilkat.StringBuilder sbResponse = new Chilkat.StringBuilder();
sbResponse.Append("HTTP/1.1 200 OK\r\n");
sbResponse.Append("Content-Length: ");
sbResponse.AppendInt(sbResponseHtml.Length);
sbResponse.Append("\r\n");
sbResponse.Append("Content-Type: text/html\r\n");
sbResponse.Append("\r\n");
sbResponse.AppendSb(sbResponseHtml);

sock.SendString(sbResponse.GetAsString());
sock.Close(50);

// The information we need is in the startLine.
// For example, the startLine will look something like this:
//  GET /?oauth_token=abcdRQAAZZAAxfBBAAABVabcd_k&oauth_verifier=9rdOq5abcdCe6cn8M3jabcdj3Eabcd&org=mUkIZabcdKEababcd189t0 HTTP/1.1
Chilkat.StringBuilder sbStartLine = new Chilkat.StringBuilder();
sbStartLine.Append(startLine);
int numReplacements = sbStartLine.Replace("GET /?","");
numReplacements = sbStartLine.Replace(" HTTP/1.1","");
sbStartLine.Trim();

// oauth_token=abcdRQAAZZAAxfBBAAABVabcd_k&oauth_verifier=9rdOq5abcdCe6cn8M3jabcdj3Eabcd&org=mUkIZabcdKEababcd189t0
Debug.WriteLine("startline: " + sbStartLine.GetAsString());

hashTab.Clear();
hashTab.AddQueryParams(sbStartLine.GetAsString());

requestToken = hashTab.LookupStr("oauth_token");
string authVerifier = hashTab.LookupStr("oauth_verifier");

// ------------------------------------------------------------------------------
// Finally , we must exchange the OAuth Request Token for an OAuth Access Token.

http.OAuthToken = requestToken;
http.OAuthVerifier = authVerifier;
resp = http.PostUrlEncoded(accessTokenUrl,req);
if (http.LastMethodSuccess != true) {
    Debug.WriteLine(http.LastErrorText);
    return;
}

// Make sure a successful response was received.
if (resp.StatusCode != 200) {
    Debug.WriteLine(resp.StatusLine);
    Debug.WriteLine(resp.Header);
    Debug.WriteLine(resp.BodyStr);
    return;
}

// If successful, the resp.BodyStr contains something like this:
// oauth_token=85123455-fF41296Bi3daM8eCo9Y5vZabcdxXpRv864plYPOjr&oauth_token_secret=afiYJOgabcdSfGae7BDvJVVTwys8fUGpra5guZxbmFBZo&oauth_expires_in=1800&xero_org_muid=abcdecNhPKabcdNjz189t0
Debug.WriteLine(resp.BodyStr);

hashTab.Clear();
hashTab.AddQueryParams(resp.BodyStr);

string accessToken = hashTab.LookupStr("oauth_token");
string accessTokenSecret = hashTab.LookupStr("oauth_token_secret");
string orgMuid = hashTab.LookupStr("xero_org_muid");
string expiresIn = hashTab.LookupStr("oauth_expires_in");

// The access token + secret is what should be saved and used for
// subsequent REST API calls.
Debug.WriteLine("Access Token = " + accessToken);
Debug.WriteLine("Access Token Secret = " + accessTokenSecret);
Debug.WriteLine("xero_org_muid = " + orgMuid);
Debug.WriteLine("oauth_expires_in  = " + expiresIn);

// Save this access token for future calls.
// Just in case we need xero_org_muid and oauth_expires_in, save those also..
Chilkat.JsonObject json = new Chilkat.JsonObject();
json.AppendString("oauth_token",accessToken);
json.AppendString("oauth_token_secret",accessTokenSecret);
json.AppendString("xero_org_muid",orgMuid);
json.AppendString("oauth_expires_in",expiresIn);

Chilkat.FileAccess fac = new Chilkat.FileAccess();
fac.WriteEntireTextFile("qa_data/tokens/xero.json",json.Emit(),"utf-8",false);

Debug.WriteLine("Success.");