ssh2preferences.java

一个非常好的ssh客户端实现

	{ "cast128-ofb",     "CAST128/OFB" },
	{ "idea-cbc",        "IDEA/CBC" },
	{ "idea-ecb",        "IDEA/ECB" },
	{ "idea-cfb",        "IDEA/CFB" },
	{ "idea-ofb",        "IDEA/OFB" },
	{ "arcfour",         "RC4/OFB" }
    };

    final static String[][] macs = {
	{ "hmac-sha1", "HmacSHA1" },
	{ "hmac-md5", "HmacMD5" },
	{ "hmac-ripemd160", "HmacRIPEMD160" },
	{ "hmac-sha1-96", "HmacSHA1-96" },
	{ "hmac-md5-96", "HmacMD5-96" },
	{ "hmac-ripemd160-96", "HmacRIPEMD160-96" },
	{ "[e-mail]", "HmacRIPEMD160" }
    };

    private final static Properties defaultProperties = new Properties();

    static {
	String stdCiphers =
	    "aes128-ctr,aes128-cbc,blowfish-ctr,blowfish-cbc,aes256-ctr,aes256-cbc,3des-cre,3des-cbc,arcfour";
	defaultProperties.put(KEX_ALGORITHMS, "diffie-hellman-group1-sha1");
	defaultProperties.put(HOST_KEY_ALG, "ssh-dss,ssh-rsa");
	defaultProperties.put(CIPHERS_C2S, stdCiphers);
	defaultProperties.put(CIPHERS_S2C, stdCiphers);
	defaultProperties.put(MACS_C2S, "hmac-md5,hmac-sha1");
	defaultProperties.put(MACS_S2C, "hmac-md5,hmac-sha1");
	defaultProperties.put(COMP_C2S, "none");
	defaultProperties.put(COMP_S2C, "none");
	defaultProperties.put(LANG_C2S, "");
	defaultProperties.put(LANG_S2C, "");

	defaultProperties.put(RX_INIT_WIN_SZ, "32768");
	defaultProperties.put(RX_MAX_PKT_SZ,  "8192");
	defaultProperties.put(TX_MAX_PKT_SZ,  "8192");
	defaultProperties.put(X11_DISPLAY, "127.0.0.1:0");
	defaultProperties.put(QUEUED_RX_CHAN, "true");
	defaultProperties.put(DEFAULT_PKT_SZ, "8192");
	defaultProperties.put(PKT_POOL_SZ, "64");
	defaultProperties.put(TERM_MIN_LAT, "false");
	defaultProperties.put(INT_IO_BUF_SZ, "65536");
	defaultProperties.put(QUEUE_DEPTH, "64");
	defaultProperties.put(QUEUE_HIWATER, "32");
	defaultProperties.put(LOG_LEVEL, "3");
	defaultProperties.put(ALIVE, "0");
    };

    private Properties preferences;
    private Hashtable  kexAgreedAlgs;

    private boolean sameKEXGuess;
    private boolean haveAgreed;
    private String  disagreeType;

    public SSH2Preferences() {
	this.preferences   = new Properties(defaultProperties);
	this.kexAgreedAlgs = new Hashtable();
    }

    public SSH2Preferences(Properties props) {
	this();
	Enumeration names = props.propertyNames();
	while(names.hasMoreElements()) {
	    String name  = (String)names.nextElement();
	    String value = props.getProperty(name);
	    preferences.put(name, value);
	}
    }

    public static Properties getDefaultProperties() {
	return defaultProperties;
    }

    public void readFrom(SSH2TransportPDU pdu) {
	for(int i = 0; i < 10; i++) {
	    setPreference(kexFields[i], pdu.readJavaString());
	}
    }

    public void writeTo(SSH2TransportPDU pdu) {
	for(int i = 0; i < 10; i++) {
	    pdu.writeString(getPreference(kexFields[i]));
	}
    }

    public String getPreference(String type) {
	return preferences.getProperty(type);
    }

    public int getIntPreference(String type) {
	try {
	    return Integer.parseInt(getPreference(type));
	} catch (NumberFormatException e) {
	    throw new NumberFormatException("Illegal value of '" + type +
					    "' expected integer but got '" +
					    getPreference(type) + "'");
	}
    }

    public void setPreference(String type, String value) {
	preferences.put(type, value);
    }

    public String getAgreedKEXAlgorithm() {
	return (String)kexAgreedAlgs.get(KEX_ALGORITHMS);
    }

    public String getAgreedHostKeyAlgorithm() {
	return (String)kexAgreedAlgs.get(HOST_KEY_ALG);
    }

    public String getAgreedCipher(boolean transmitter, boolean weAreAServer) {
	String type = ((transmitter ^ weAreAServer) ? CIPHERS_C2S : CIPHERS_S2C);
	return (String)kexAgreedAlgs.get(type);
    }

    public String getAgreedMac(boolean transmitter, boolean weAreAServer) {
	String type = ((transmitter ^ weAreAServer) ? MACS_C2S : MACS_S2C);
	return (String)kexAgreedAlgs.get(type);
    }

    public String getAgreedCompression(boolean transmitter,
				       boolean weAreAServer)
    {
	String type = ((transmitter ^ weAreAServer) ? COMP_C2S : COMP_S2C);
	return (String)kexAgreedAlgs.get(type);
    }

    public boolean isSupported(String type, String item) {
	String list = getPreference(type);
	return SSH2ListUtil.isInList(list, item);
    }

    public SSH2KeyExchanger
	selectKEXAlgorithm(SSH2Preferences peerPrefs, boolean weAreAServer)
	throws SSH2KEXFailedException
    {
	SSH2KeyExchanger kexImpl = null;
	String           cliKEXList, srvKEXList, cliHKAList, srvHKAList;

	if(weAreAServer) {
	    cliKEXList = peerPrefs.getPreference(KEX_ALGORITHMS);
	    srvKEXList = getPreference(KEX_ALGORITHMS);
	    cliHKAList = peerPrefs.getPreference(HOST_KEY_ALG);
	    srvHKAList = getPreference(HOST_KEY_ALG);
	} else {
	    cliKEXList = getPreference(KEX_ALGORITHMS);
	    srvKEXList = peerPrefs.getPreference(KEX_ALGORITHMS);
	    cliHKAList = getPreference(HOST_KEY_ALG);
	    srvHKAList = peerPrefs.getPreference(HOST_KEY_ALG);
	}

	String kexAlgorithm     = SSH2ListUtil.getFirstInList(cliKEXList);
	String hostKeyAlgorithm = null;

	while(kexAlgorithm != null) {
	    kexImpl          = SSH2KeyExchanger.getInstance(kexAlgorithm);
	    hostKeyAlgorithm = chooseHostKeyAlgorithm(cliHKAList, srvHKAList,
					      kexImpl.getHostKeyAlgorithms());
	    if(hostKeyAlgorithm != null) {
		break;
	    }
	    cliKEXList = SSH2ListUtil.removeFirstFromList(cliKEXList,
							  kexAlgorithm);
	    kexAlgorithm = SSH2ListUtil.getFirstInList(cliKEXList);
	}

	if(kexAlgorithm == null) {
	    String msg = "Couldn't agree on kex algorithm (our: '" +
		getPreference(KEX_ALGORITHMS) + "', peer: '" +
		peerPrefs.getPreference(KEX_ALGORITHMS) + "')";
	    throw new SSH2KEXFailedException(msg);
	}

	sameKEXGuess =
	    kexAlgorithm.equals(SSH2ListUtil.getFirstInList(srvKEXList)) &&
	    hostKeyAlgorithm.equals(SSH2ListUtil.getFirstInList(srvHKAList));

	kexAgreedAlgs.put(KEX_ALGORITHMS, kexAlgorithm);
	kexAgreedAlgs.put(HOST_KEY_ALG, hostKeyAlgorithm);

	return kexImpl;
    }

    public boolean sameKEXGuess() {
	return sameKEXGuess;
    }

    public boolean canAgree(SSH2Preferences peerPrefs, boolean weAreAServer) {
	haveAgreed = true;
	/*
	 * !!! TODO: we currently ignore language preferences here
	 */
	for(int i = 2; i < 8; i++) {
	    String type = kexFields[i];
	    String alg = choosePref(type, peerPrefs, weAreAServer);
	    if(alg == null) {
		haveAgreed   = false;
		sameKEXGuess = false;
		disagreeType = type;
		break;
	    }
	    kexAgreedAlgs.put(type, alg);
	}
	return haveAgreed;
    }

    public String getDisagreeType() {
	return disagreeType;
    }

    private String chooseHostKeyAlgorithm(String cliHKAList, String srvHKAList,
					 String kexHKAList) {
	String alg = SSH2ListUtil.chooseFromList(cliHKAList, kexHKAList);
	while(alg != null && !SSH2ListUtil.isInList(srvHKAList, alg)) {
	    cliHKAList = SSH2ListUtil.removeFirstFromList(cliHKAList, alg);
	    alg        = SSH2ListUtil.chooseFromList(cliHKAList, kexHKAList);
	}
	return alg;
    }

    private String choosePref(String type, SSH2Preferences peerPrefs,
			      boolean weAreAServer)
    {
	String clientList, serverList;
	if(weAreAServer) {
	    clientList = peerPrefs.getPreference(type);
	    serverList = getPreference(type);
	} else {
	    clientList = getPreference(type);
	    serverList = peerPrefs.getPreference(type);
	}
	return SSH2ListUtil.chooseFromList(clientList, serverList);
    }

    public static String ssh2ToJCECipher(String prefCipher) {
	for(int i = 0; i < ciphers.length; i++) {
	    if(ciphers[i][0].equals(prefCipher))
		return ciphers[i][1];
	}
	return null;
    }

    public static String ssh2ToJCEMac(String prefMac) {
	for(int i = 0; i < macs.length; i++) {
	    if(macs[i][0].startsWith(prefMac))
		return macs[i][1];
	}
	return null;
    }

    public static int getCipherKeyLen(String cipherName) {
	int len = 128;
	if(cipherName != null) {
	    cipherName = cipherName.toLowerCase();
	    if(cipherName.indexOf("128") != -1) {
		len = 128;
	    } else if(cipherName.indexOf("192") != -1) {
		len = 192;
	    } else if(cipherName.indexOf("256") != -1) {
		len = 256;
	    } else if(cipherName.startsWith("twofish") ||
		      cipherName.startsWith("rijndael") ||
		      cipherName.startsWith("aes")) {
		len = 256;
	    } else if(cipherName.startsWith("3des")) {
		len = 192;
	    }
	}
	return len / 8;
    }

    public static int getMacKeyLen(String macName) {
	int len = 16;
	if(macName != null && ((macName.indexOf("SHA") != -1) ||
			       (macName.indexOf("sha") != -1) ||
			       (macName.indexOf("ripemd160") != -1))) {
	    len = 20;
	}
	return len;
    }

}