From d8d0d2f66a5da5b7995530dd748cf922ef9c5b5e Mon Sep 17 00:00:00 2001
From: CyB3RC0nN0R <kske@outlook.de>
Date: Sat, 20 Jun 2020 14:38:06 +0200
Subject: [PATCH] Add simple version comparison algorithm

---
 .../processors/LoginCredentialProcessor.java  | 65 +++++++++++++++++--
 1 file changed, 58 insertions(+), 7 deletions(-)

diff --git a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
index f837656..5ab8cc6 100755
--- a/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
+++ b/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
@@ -8,6 +8,7 @@ import java.time.LocalDateTime;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.logging.Logger;
+import java.util.regex.Pattern;
 
 import javax.persistence.NoResultException;
 
@@ -38,9 +39,8 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 	private final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
 	private final ConnectionManager		connectionManager	= ConnectionManager.getInstance();
 
-	private static final Logger logger = EnvoyLog.getLogger(LoginCredentialProcessor.class);
-	// private static final Pattern versionPattern =
-	// Pattern.compile("v(?<major>\\d).(?<minor>\\d)(?:-(?<suffix>\\w+))?");
+	private static final Logger		logger			= EnvoyLog.getLogger(LoginCredentialProcessor.class);
+	private static final Pattern	versionPattern	= Pattern.compile("(?<major>\\d).(?<minor>\\d)(?:-(?<suffix>\\w+))?");
 
 	@Override
 	public void process(LoginCredentials credentials, long socketID, ObjectWriteProxy writeProxy) throws IOException {
@@ -49,10 +49,10 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 		UserStatusChangeProcessor.setWriteProxy(writeProxy);
 
 		// TODO: Verify compatibility
-		if (Startup.MIN_CLIENT_VERSION.compareTo(credentials.getClientVersion()) <= 0
-				&& Startup.MAX_CLIENT_VERSION.compareTo(credentials.getClientVersion()) >= 0) {
-			// writeProxy.write(socketID, new HandshakeRejectionEvent("Wrong version"));
-			// return;
+		if (!verifyCompatibility(credentials.getClientVersion())) {
+			logger.info("The client has the wrong version.");
+			writeProxy.write(socketID, new HandshakeRejection("Wrong version"));
+			return;
 		}
 
 		// Acquire a user object (or reject the handshake if that's impossible)
@@ -125,6 +125,57 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 		}
 	}
 
+	private boolean verifyCompatibility(String version) {
+		final var currentMatcher = versionPattern.matcher(version);
+
+		if (!currentMatcher.matches()) return false;
+
+		final var	minMatcher	= versionPattern.matcher(Startup.MIN_CLIENT_VERSION);
+		final var	maxMatcher	= versionPattern.matcher(Startup.MAX_CLIENT_VERSION);
+
+		if (!minMatcher.matches() || !maxMatcher.matches()) throw new RuntimeException("Invalid min or max client version configured!");
+
+		// Compare suffixes
+		{
+			final var	currentSuffix	= convertSuffix(currentMatcher.group("suffix"));
+			final var	minSuffix		= convertSuffix(minMatcher.group("suffix"));
+			final var	maxSuffix		= convertSuffix(maxMatcher.group("suffix"));
+
+			if (currentSuffix < minSuffix || currentSuffix > maxSuffix) return false;
+		}
+
+		// Compare major
+		{
+			final var	currentMajor	= Integer.parseInt(currentMatcher.group("major"));
+			final var	minMajor		= Integer.parseInt(minMatcher.group("major"));
+			final var	maxMajor		= Integer.parseInt(maxMatcher.group("major"));
+
+			if (currentMajor < minMajor || currentMajor > maxMajor) return false;
+		}
+
+		// Compare minor
+		{
+			final var	currentMinor	= Integer.parseInt(currentMatcher.group("minor"));
+			final var	minMinor		= Integer.parseInt(minMatcher.group("minor"));
+			final var	maxMinor		= Integer.parseInt(maxMatcher.group("minor"));
+
+			if (currentMinor < minMinor || currentMinor > maxMinor) return false;
+		}
+
+		return true;
+	}
+
+	private int convertSuffix(String suffix) {
+		switch (suffix == null ? "" : suffix) {
+			case "alpha":
+				return 0;
+			case "beta":
+				return 1;
+			default:
+				return 2;
+		}
+	}
+
 	@Override
 	public Class<LoginCredentials> getInputClass() { return LoginCredentials.class; }
 }