Add a simple Tor relay probe.

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorProbe.java

@@ -0,0 +1,153 @@
+package org.briarproject.bramble.plugin.tor;
+
+import org.spongycastle.crypto.tls.Certificate;
+import org.spongycastle.crypto.tls.CipherSuite;
+import org.spongycastle.crypto.tls.DefaultTlsClient;
+import org.spongycastle.crypto.tls.ServerOnlyTlsAuthentication;
+import org.spongycastle.crypto.tls.TlsAuthentication;
+import org.spongycastle.crypto.tls.TlsClientProtocol;
+
+import java.io.DataInputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.Socket;
+import java.security.SecureRandom;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.INFO;
+
+public class TorProbe {
+
+	private static final Logger LOG =
+			Logger.getLogger(TorProbe.class.getName());
+
+	private static final int READ_TIMEOUT = 10 * 1000;
+
+	// https://trac.torproject.org/projects/tor/wiki/org/projects/Tor/TLSHistory
+	private static final int SSL3_RSA_FIPS_WITH_3DES_EDE_CBC_SHA = 0xfeff;
+
+	// https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n347
+	private static final int[] TOR_CIPHER_SUITES = new int[] {
+			CipherSuite.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
+			CipherSuite.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
+			CipherSuite.TLS_DHE_RSA_WITH_AES_256_CBC_SHA,
+			CipherSuite.TLS_DHE_DSS_WITH_AES_256_CBC_SHA,
+			CipherSuite.TLS_ECDH_RSA_WITH_AES_256_CBC_SHA,
+			CipherSuite.TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA,
+			CipherSuite.TLS_RSA_WITH_AES_256_CBC_SHA,
+			CipherSuite.TLS_ECDHE_ECDSA_WITH_RC4_128_SHA,
+			CipherSuite.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
+			CipherSuite.TLS_ECDHE_RSA_WITH_RC4_128_SHA,
+			CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
+			CipherSuite.TLS_DHE_RSA_WITH_AES_128_CBC_SHA,
+			CipherSuite.TLS_DHE_DSS_WITH_AES_128_CBC_SHA,
+			CipherSuite.TLS_ECDH_RSA_WITH_RC4_128_SHA,
+			CipherSuite.TLS_ECDH_RSA_WITH_AES_128_CBC_SHA,
+			CipherSuite.TLS_ECDH_ECDSA_WITH_RC4_128_SHA,
+			CipherSuite.TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA,
+			CipherSuite.TLS_RSA_WITH_RC4_128_MD5,
+			CipherSuite.TLS_RSA_WITH_RC4_128_SHA,
+			CipherSuite.TLS_RSA_WITH_AES_128_CBC_SHA,
+			CipherSuite.TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA,
+			CipherSuite.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
+			CipherSuite.TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA,
+			CipherSuite.TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA,
+			CipherSuite.TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA,
+			CipherSuite.TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA,
+			SSL3_RSA_FIPS_WITH_3DES_EDE_CBC_SHA,
+			CipherSuite.TLS_RSA_WITH_3DES_EDE_CBC_SHA
+	};
+
+	// https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n412
+	private static final byte[] VERSIONS_CELL = new byte[] {
+			0x00, 0x00, // Circuit ID: 0
+			0x07, // Command: Versions
+			0x00, 0x06, // Payload length: 6 bytes
+			0x00, 0x03, 0x00, 0x04, 0x00, 0x05 // Supported versions: 3, 4, 5
+	};
+
+	public List<Integer> probe(String address, int port) throws IOException {
+		if (LOG.isLoggable(INFO))
+			LOG.info("Connecting to " + address + ":" + port);
+		Socket socket = new Socket(address, port);
+		LOG.info("Connected");
+		TlsClientProtocol client = new TlsClientProtocol(
+				socket.getInputStream(), socket.getOutputStream(),
+				new SecureRandom());
+		client.connect(new TorTlsClient());
+		LOG.info("TLS handshake succeeded");
+		socket.setSoTimeout(READ_TIMEOUT);
+		try {
+			// Send a versions cell
+			OutputStream out = client.getOutputStream();
+			out.write(VERSIONS_CELL);
+			out.flush();
+			LOG.info("Sent versions cell");
+
+			// Expect a versions cell in response
+			List<Integer> versions = new ArrayList<>();
+			DataInputStream in = new DataInputStream(client.getInputStream());
+			int circuitId = in.readUnsignedShort();
+			if (circuitId != 0)
+				throw new IOException("Unexpected circuit ID: " + circuitId);
+			int command = in.readUnsignedByte();
+			if (command != 7)
+				throw new IOException("Unexpected command: " + command);
+			int payloadLength = in.readUnsignedShort();
+			if (payloadLength == 0 || payloadLength % 2 != 0) {
+				throw new IOException("Invalid payload length: "
+						+ payloadLength);
+			}
+			for (int i = 0; i < payloadLength / 2; i++) {
+				int version = in.readUnsignedShort();
+				versions.add(version);
+			}
+			if (LOG.isLoggable(INFO))
+				LOG.info("Supported versions: " + versions);
+			return versions;
+		} finally {
+			client.close();
+		}
+	}
+
+	public static void main(String[] args) throws IOException {
+		if (args.length != 2) {
+			System.err.println("Usage: TorProbe <address> <port>");
+			System.exit(1);
+		}
+		String address = args[0];
+		int port = Integer.parseInt(args[1]);
+		new TorProbe().probe(address, port);
+	}
+
+	private static class TorTlsClient extends DefaultTlsClient {
+
+		@Override
+		public TlsAuthentication getAuthentication() {
+			return new ServerOnlyTlsAuthentication() {
+				@Override
+				public void notifyServerCertificate(Certificate cert)
+						throws IOException {
+					LOG.info("Received server certificate");
+					org.spongycastle.asn1.x509.Certificate[] chain =
+							cert.getCertificateList();
+					if (chain.length != 1)
+						throw new IOException("Certificate is not self-signed");
+					for (org.spongycastle.asn1.x509.Certificate c : chain) {
+						if (LOG.isLoggable(INFO)) {
+							LOG.info("Subject: " + c.getSubject());
+							LOG.info("Issuer: " + c.getIssuer());
+						}
+					}
+				}
+			};
+		}
+
+		@Override
+		public int[] getCipherSuites() {
+			return TOR_CIPHER_SUITES;
+		}
+	}
+}