Пример #1
0
  /**
   * Compute the hash an IP address. The hash is the first 8 bytes of the SHA digest of the IP
   * address.
   */
  private static byte[] computeAddressHash() {

    /*
     * Get the local host's IP address.
     */
    byte[] addr =
        (byte[])
            java.security.AccessController.doPrivileged(
                new PrivilegedAction() {
                  public Object run() {
                    try {
                      return InetAddress.getLocalHost().getAddress();
                    } catch (Exception e) {
                    }
                    return new byte[] {0, 0, 0, 0};
                  }
                });

    byte[] addrHash;
    final int ADDR_HASH_LENGTH = 8;

    try {
      /*
       * Calculate message digest of IP address using SHA.
       */
      MessageDigest md = MessageDigest.getInstance("SHA");
      ByteArrayOutputStream sink = new ByteArrayOutputStream(64);
      DataOutputStream out = new DataOutputStream(new DigestOutputStream(sink, md));
      out.write(addr, 0, addr.length);
      out.flush();

      byte digest[] = md.digest();
      int hashlength = Math.min(ADDR_HASH_LENGTH, digest.length);
      addrHash = new byte[hashlength];
      System.arraycopy(digest, 0, addrHash, 0, hashlength);

    } catch (IOException ignore) {
      /* can't happen, but be deterministic anyway. */
      addrHash = new byte[0];
    } catch (NoSuchAlgorithmException complain) {
      throw new InternalError(complain.toString());
    }
    return addrHash;
  }
Пример #2
0
  /** Utility routine for setting the context class loader. Returns previous class loader. */
  public static ClassLoader setContextClassLoader(ClassLoader newClassLoader) {

    // Can only reference final local variables from dopriveleged block
    final ClassLoader classLoaderToSet = newClassLoader;

    final Thread currentThread = Thread.currentThread();
    ClassLoader originalClassLoader = currentThread.getContextClassLoader();

    if (classLoaderToSet != originalClassLoader) {
      if (System.getSecurityManager() == null) {
        currentThread.setContextClassLoader(classLoaderToSet);
      } else {
        java.security.AccessController.doPrivileged(
            new java.security.PrivilegedAction() {
              public java.lang.Object run() {
                currentThread.setContextClassLoader(classLoaderToSet);
                return null;
              }
            });
      }
    }
    return originalClassLoader;
  }