1 files changed, 65 insertions, 53 deletions
diff --git a/src/main/java/eu/siacs/conversations/crypto/sasl/DigestMd5.java b/src/main/java/eu/siacs/conversations/crypto/sasl/DigestMd5.java
index f81bd0c5..bef76fef 100644
--- a/src/main/java/eu/siacs/conversations/crypto/sasl/DigestMd5.java
+++ b/src/main/java/eu/siacs/conversations/crypto/sasl/DigestMd5.java
@@ -13,60 +13,72 @@ import eu.siacs.conversations.utils.CryptoHelper;
 import eu.siacs.conversations.xml.TagWriter;
 
 public class DigestMd5 extends SaslMechanism {
-    public DigestMd5(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
-        super(tagWriter, account, rng);
-    }
+	public DigestMd5(final TagWriter tagWriter, final Account account, final SecureRandom rng) {
+		super(tagWriter, account, rng);
+	}
 
-    @Override
-    public String getMechanism() {
-        return "DIGEST-MD5";
-    }
+	public static String getMechanism() {
+		return "DIGEST-MD5";
+	}
 
-    @Override
-    public String getResponse(final String challenge) {
-        final String encodedResponse;
-        try {
-            final String[] challengeParts = new String(Base64.decode(challenge,
-                    Base64.DEFAULT)).split(",");
-            String nonce = "";
-            for (int i = 0; i < challengeParts.length; ++i) {
-                String[] parts = challengeParts[i].split("=");
-                if (parts[0].equals("nonce")) {
-                    nonce = parts[1].replace("\"", "");
-                } else if (parts[0].equals("rspauth")) {
-                    return "";
-                }
-            }
-            final String digestUri = "xmpp/" + account.getServer();
-            final String nonceCount = "00000001";
-            final String x = account.getUsername() + ":" + account.getServer() + ":"
-                    + account.getPassword();
-            final MessageDigest md = MessageDigest.getInstance("MD5");
-            final byte[] y = md.digest(x.getBytes(Charset.defaultCharset()));
-            final String cNonce = new BigInteger(100, rng).toString(32);
-            final byte[] a1 = CryptoHelper.concatenateByteArrays(y,
-                    (":" + nonce + ":" + cNonce).getBytes(Charset
-                            .defaultCharset()));
-            final String a2 = "AUTHENTICATE:" + digestUri;
-            final String ha1 = CryptoHelper.bytesToHex(md.digest(a1));
-            final String ha2 = CryptoHelper.bytesToHex(md.digest(a2.getBytes(Charset
-                    .defaultCharset())));
-            final String kd = ha1 + ":" + nonce + ":" + nonceCount + ":" + cNonce
-                    + ":auth:" + ha2;
-            final String response = CryptoHelper.bytesToHex(md.digest(kd.getBytes(Charset
-                    .defaultCharset())));
-            final String saslString = "username=\"" + account.getUsername()
-                    + "\",realm=\"" + account.getServer() + "\",nonce=\""
-                    + nonce + "\",cnonce=\"" + cNonce + "\",nc=" + nonceCount
-                    + ",qop=auth,digest-uri=\"" + digestUri + "\",response="
-                    + response + ",charset=utf-8";
-            encodedResponse = Base64.encodeToString(
-                    saslString.getBytes(Charset.defaultCharset()),
-                    Base64.NO_WRAP);
-        } catch (final NoSuchAlgorithmException e) {
-            return "";
-        }
+	private enum State {
+		INITIAL,
+		RESPONSE_SENT,
+	}
 
-        return encodedResponse;
-    }
+	private State state = State.INITIAL;
+
+	@Override
+	public String getResponse(final String challenge) throws AuthenticationException {
+		switch (state) {
+			case INITIAL:
+				state = State.RESPONSE_SENT;
+				final String encodedResponse;
+				try {
+					final Tokenizer tokenizer = new Tokenizer(Base64.decode(challenge, Base64.DEFAULT));
+					String nonce = "";
+					for (final String token : tokenizer) {
+						final String[] parts = token.split("=");
+						if (parts[0].equals("nonce")) {
+							nonce = parts[1].replace("\"", "");
+						} else if (parts[0].equals("rspauth")) {
+							return "";
+						}
+					}
+					final String digestUri = "xmpp/" + account.getServer();
+					final String nonceCount = "00000001";
+					final String x = account.getUsername() + ":" + account.getServer() + ":"
+						+ account.getPassword();
+					final MessageDigest md = MessageDigest.getInstance("MD5");
+					final byte[] y = md.digest(x.getBytes(Charset.defaultCharset()));
+					final String cNonce = new BigInteger(100, rng).toString(32);
+					final byte[] a1 = CryptoHelper.concatenateByteArrays(y,
+							(":" + nonce + ":" + cNonce).getBytes(Charset
+																										.defaultCharset()));
+					final String a2 = "AUTHENTICATE:" + digestUri;
+					final String ha1 = CryptoHelper.bytesToHex(md.digest(a1));
+					final String ha2 = CryptoHelper.bytesToHex(md.digest(a2.getBytes(Charset
+									.defaultCharset())));
+					final String kd = ha1 + ":" + nonce + ":" + nonceCount + ":" + cNonce
+						+ ":auth:" + ha2;
+					final String response = CryptoHelper.bytesToHex(md.digest(kd.getBytes(Charset
+									.defaultCharset())));
+					final String saslString = "username=\"" + account.getUsername()
+						+ "\",realm=\"" + account.getServer() + "\",nonce=\""
+						+ nonce + "\",cnonce=\"" + cNonce + "\",nc=" + nonceCount
+						+ ",qop=auth,digest-uri=\"" + digestUri + "\",response="
+						+ response + ",charset=utf-8";
+					encodedResponse = Base64.encodeToString(
+							saslString.getBytes(Charset.defaultCharset()),
+							Base64.NO_WRAP);
+				} catch (final NoSuchAlgorithmException e) {
+					return "";
+				}
+
+				return encodedResponse;
+			case RESPONSE_SENT:
+				return "";
+		}
+		return "";
+	}
 }