Previously, we’ve featured something about the subject matter: Using the undocumented Rest API: authentication and invocation of Tableau Server
In that post we’ve described the mechanism behind tableau webservice authentication in details. This article is a really close follow up in Java, where we will be using apache HTTPClient and a maven project.
The basic steps are:
- Create an HTTP request to get the modulus and exponent of the servers public RSA key and the authencity_token from “/auth.xml”
- parse the xml to get the corresponding values
- create the RSA public key from the values and encode the user password
- send back the username, encoded user password and authencity_token for the webservice to “/auth/login.xml”
- give back the authenticated HTTPClient to the user
You can download the github maven project which includes dependencies from here, or if you only want to check out the code, here it is:
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/** * */ package tableauSrvrWebservice.Auth; /** * @author Horváth Attila * @created 2013.08.02 * */ import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.StringReader; import java.math.BigInteger; import java.security.InvalidKeyException; import java.security.KeyFactory; import java.security.NoSuchAlgorithmException; import java.security.PublicKey; import java.security.spec.InvalidKeySpecException; import java.security.spec.RSAPublicKeySpec; import java.util.ArrayList; import java.util.List; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.NoSuchPaddingException; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.apache.commons.codec.binary.Hex; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; import org.w3c.dom.Document; import org.w3c.dom.Element; import org.w3c.dom.NodeList; import org.xml.sax.InputSource; import org.xml.sax.SAXException; public class WebServiceClient { /** * Fetches The httpresp HttpResponse into a StringBuffer * * @param httpresp * HttpResponse * @return StringBuffer with contents of the HttpResponse * @throws IOException */ public static StringBuffer fetchResponse(HttpResponse httpresp) throws IOException { BufferedReader bufferedReader = new BufferedReader( new InputStreamReader(httpresp.getEntity().getContent())); StringBuffer strbuffer = new StringBuffer(); String currentline = ""; while ((currentline = bufferedReader.readLine()) != null) { strbuffer.append(currentline); } return strbuffer; } /** * Creates a HttpClient with authenticated connection to the Tableau Server * * @param serveraddress * - URL address of the Tableau Server * @param user * - Username on Tableau Server * @param password * - Corresponding password to the Username * @return HttpClient with authenticated connection to the Tableau Server * @throws ClientProtocolException * @throws IOException * @throws ParserConfigurationException * @throws SAXException * @throws NoSuchAlgorithmException * @throws InvalidKeySpecException * @throws NoSuchPaddingException * @throws InvalidKeyException * @throws IllegalBlockSizeException * @throws BadPaddingException */ public static HttpClient authenticate(String serveraddress, String user, String password) throws ClientProtocolException, IOException, ParserConfigurationException, SAXException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException { // Initialize apache HttpClient HttpClient client = new DefaultHttpClient(); // Create Http Get request for authentication informations String url = serveraddress + "/auth.xml"; HttpGet request = new HttpGet(url); HttpResponse response = client.execute(request); StringBuffer result = fetchResponse(response); // Parse XML FROM the result StringReader reader = new StringReader(result.toString()); DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); DocumentBuilder db = dbf.newDocumentBuilder(); InputSource is = new InputSource(); is.setCharacterStream(reader); Document doc = db.parse(is); // Get Required data for creating the authentication request, such as // modulus and exponent of the RSA public key and the authencity_token String modulusstr = null; String exponentstr = null; String authencity_token = null; NodeList elements = doc.getElementsByTagName("authinfo"); for (int i = 0; i < elements.getLength(); i++) { NodeList moduluses = ((Element) elements.item(i)) .getElementsByTagName("modulus"); for (int k = 0; k < moduluses.getLength(); k++) { modulusstr = moduluses.item(k).getTextContent(); } NodeList exponents = ((Element) elements.item(i)) .getElementsByTagName("exponent"); for (int k = 0; k < exponents.getLength(); k++) { exponentstr = exponents.item(k).getTextContent(); } NodeList authencity_tokens = ((Element) elements.item(i)) .getElementsByTagName("authenticity_token"); for (int k = 0; k < exponents.getLength(); k++) { authencity_token = authencity_tokens.item(k).getTextContent(); } } // Parse the modulus and exponent into a BigInteger and create an RSA // public key from it BigInteger modulus = new BigInteger(modulusstr, 16); BigInteger exponent = new BigInteger(exponentstr, 16); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); RSAPublicKeySpec pub = new RSAPublicKeySpec(modulus, exponent); PublicKey pubkey = keyFactory.generatePublic(pub); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, pubkey); // Encrypt the password with the created public key byte[] cipherData = cipher.doFinal(password.getBytes()); String cryptedpass = Hex.encodeHexString(cipherData); // Create a post request for the authentication HttpPost postrequest = new HttpPost(serveraddress + "/auth/login.xml"); // Fill in parameters List<NameValuePair> nvps = new ArrayList<NameValuePair>(); nvps.add(new BasicNameValuePair("authenticity_token", authencity_token)); nvps.add(new BasicNameValuePair("crypted", cryptedpass)); nvps.add(new BasicNameValuePair("username", user)); // bind parameters to the request postrequest.setEntity(new UrlEncodedFormEntity(nvps)); HttpResponse postResponse = client.execute(postrequest); // We clear the entity here so we don't have to shutdown the client fetchResponse(postResponse); return client; } } |
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Tamás Földi
Director of IT Development at Starschema
Decades of experience with data processing and state of the art programming. From nuclear bomb explosion simulation to distributed file systems. ethical hacking, real time stream processing practically I always had a great fun with those geeky ones and zeros.
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