adds the ability to do reverse auth

Author: casualjim

api/src/main/java/com/ning/http/client/oauth/OAuthSignatureCalculator.java

@@ -52,9 +52,11 @@ public class OAuthSignatureCalculator
     private static final String KEY_OAUTH_TIMESTAMP = "oauth_timestamp";
     private static final String KEY_OAUTH_TOKEN = "oauth_token";
     private static final String KEY_OAUTH_VERSION = "oauth_version";
+    private static final String KEY_X_AUTH_MODE = "x_auth_mode";
 
     private static final String OAUTH_VERSION_1_0 = "1.0";
     private static final String OAUTH_SIGNATURE_METHOD = "HMAC-SHA1";
+    private static final String OAUTH_REVERSE_AUTH = "reverse_auth";
 
     /**
      * To generate Nonce, need some (pseudo)randomness; no need for
@@ -70,15 +72,27 @@ public class OAuthSignatureCalculator
 
     protected final RequestToken userAuth;
 
+    protected final Boolean useReverseAuth;
+
     /**
      * @param consumerAuth Consumer key to use for signature calculation
      * @param userAuth     Request/access token to use for signature calculation
      */
     public OAuthSignatureCalculator(ConsumerKey consumerAuth, RequestToken userAuth) {
+      this(consumerAuth, userAuth, false);
+    }
+
+    /**
+     * @param consumerAuth   Consumer key to use for signature calculation
+     * @param userAuth       Request/access token to use for signature calculation
+     * @param useReverseAuth Whether or not to use the reverse auth signature or the regular one
+     */
+    public OAuthSignatureCalculator(ConsumerKey consumerAuth, RequestToken userAuth, Boolean useReverseAuth ) {
         mac = new ThreadSafeHMAC(consumerAuth, userAuth);
         this.consumerAuth = consumerAuth;
         this.userAuth = userAuth;
         random = new Random(System.identityHashCode(this) + System.currentTimeMillis());
+        this.useReverseAuth = useReverseAuth;
     }
 
     //@Override // silly 1.5; doesn't allow this for interfaces
@@ -130,6 +144,8 @@ public String calculateSignature(String method, String baseURL, long oauthTimest
         allParameters.add(KEY_OAUTH_TIMESTAMP, String.valueOf(oauthTimestamp));
         allParameters.add(KEY_OAUTH_TOKEN, userAuth.getKey());
         allParameters.add(KEY_OAUTH_VERSION, OAUTH_VERSION_1_0);
+        if (useReverseAuth)
+            allParameters.add(KEY_X_AUTH_MODE, OAUTH_REVERSE_AUTH);
 
         if (formParams != null) {
             for (Map.Entry<String, List<String>> entry : formParams) {
@@ -180,6 +196,8 @@ public String constructAuthHeader(String signature, String nonce, long oauthTime
         sb.append("\", ");
 
         sb.append(KEY_OAUTH_VERSION).append("=\"").append(OAUTH_VERSION_1_0).append("\"");
+        if (useReverseAuth)
+            sb.append(KEY_X_AUTH_MODE).append("=\"").append(OAUTH_REVERSE_AUTH).append("\"");
         return sb.toString();
     }