From d7652657bf13d407c34032ec4df3aebf6ac38c41 Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Thu, 25 Mar 2021 15:03:46 +0100
Subject: Add missing files

---
 src/main/java/com/btr/proxy/util/MiscUtil.java    | 26 ++++++++++
 src/main/java/com/btr/proxy/util/SocksTester.java | 60 +++++++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 src/main/java/com/btr/proxy/util/MiscUtil.java
 create mode 100644 src/main/java/com/btr/proxy/util/SocksTester.java

diff --git a/src/main/java/com/btr/proxy/util/MiscUtil.java b/src/main/java/com/btr/proxy/util/MiscUtil.java
new file mode 100644
index 0000000..cc8faaa
--- /dev/null
+++ b/src/main/java/com/btr/proxy/util/MiscUtil.java
@@ -0,0 +1,26 @@
+package com.btr.proxy.util;
+
+public class MiscUtil {
+
+	/**
+	 * Parse int, return fallback value on exception
+	 * 
+	 * @return integer
+	 */
+	public static int parseInt(String input, int radix, int fallback) {
+		try {
+			return Integer.parseInt(input, radix);
+		} catch (Exception e) {
+			return fallback;
+		}
+	}
+
+	public static int parseInt(String input, int radix) {
+		return parseInt(input, radix, -1);
+	}
+
+	public static int parseInt(String input) {
+		return parseInt(input, 10, -1);
+	}
+
+}
diff --git a/src/main/java/com/btr/proxy/util/SocksTester.java b/src/main/java/com/btr/proxy/util/SocksTester.java
new file mode 100644
index 0000000..5e8bfda
--- /dev/null
+++ b/src/main/java/com/btr/proxy/util/SocksTester.java
@@ -0,0 +1,60 @@
+package com.btr.proxy.util;
+
+import java.net.InetSocketAddress;
+import java.net.Proxy;
+import java.net.Socket;
+import java.util.Arrays;
+
+public class SocksTester {
+	
+	private static byte[] SOCKS_4_HANDSHAKE = new byte[] {
+		0x04, // Version
+		0x01, // establish connection
+		0x23, (byte)0x82, // Port 9090
+		0x01, 0x01, 0x01, 0x01, // 1.1.1.1
+		0x46, 0x72, 0x65, 0x64, 0x00 // Fred\0
+	};
+
+	/**
+	 * Connect to the given host:port and try to talk SOCKS4
+	 * to it, requesting a connection to 1.1.1.1:9090.
+	 * If the server replies using the SOCKS protocol,
+	 * we return true, false otherwise.
+	 * If mustAccept is set, we additionally check that
+	 * the SOCKS proxy actually granted the outgoing connection
+	 * request.
+	 *
+	 * @param host
+	 * @param port
+	 * @return
+	 */
+	public static boolean trySocks4(String host, int port, boolean mustAccept) {
+		Arrays.copyOf(SOCKS_4_HANDSHAKE, SOCKS_4_HANDSHAKE.length);
+		try (Socket socket = new Socket(Proxy.NO_PROXY)) {
+			socket.connect(new InetSocketAddress(host, port), 1000);
+			byte[] buffer = new byte[13];
+			buffer[0] = 0x04;
+			buffer[1] = 0x01;
+			InetSocketAddress google = new InetSocketAddress("www.google.com", 80);
+			google.getAddress().getAddress();
+			socket.getOutputStream().write(SOCKS_4_HANDSHAKE);
+			int num = socket.getInputStream().read(buffer);
+			// Wrong length or wrong header
+			if (num < 8 || buffer[0] != 0x00)
+				return false;
+			if (mustAccept) {
+				// Must be accept code
+				if (buffer[1] != 0x5A)
+					return false;
+			} else {
+				// Must be any valid return code
+				if (buffer[1] < 0x5A || buffer[1] > 0x5D)
+					return false;
+			}
+		} catch (Exception e) {
+			return false;
+		}
+		return true;
+	}
+	
+}
-- 
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