dhcppacket.java

DHCP 的JAVA实现

            // add padding if the packet is too small
            int min_padding = minSize - outBStream.size();
            if (min_padding > 0) {
                byte[] add_padding = new byte[min_padding];
                outStream.write(add_padding);
            }

            // final packet is here
            byte[] data = outBStream.toByteArray();

            // do some post sanity checks
            if (data.length > _DHCP_MAX_MTU) {
                throw new DHCPBadPacketException("serialize: packet too big (" + data.length + " greater than max MAX_MTU (" + _DHCP_MAX_MTU + ')');
            }

            return data;
        } catch (IOException e) {
            // nomrally impossible with ByteArrayOutputStream
            logger.log(Level.SEVERE, "Unexpected Exception", e);
            throw new DHCPBadPacketException("IOException raised: "+e.toString());
        }
    }

    // ========================================================================
    // debug functions

    /**
     * Returns a detailed string representation of the DHCP datagram.
     * 
     * <p>This multi-line string details: the static, options and padding parts
     * of the object. This is useful for debugging, but not efficient.
     * 
     * @return a string representation of the object.
     */
    @Override
    public String toString() {
        StringBuilder buffer = new StringBuilder(); // output buffer

        try {
            buffer.append(this.isDhcp ? "DHCP Packet" : "BOOTP Packet")
                  .append("\ncomment=")
                  .append(this.comment)
                  .append("\naddress=")
                  .append(this.address != null ? this.address.getHostAddress() : "")
                  .append('(')
                  .append(this.port)
                  .append(')')
                  .append("\nop=");

            final Object bootName = _BOOT_NAMES.get(this.op);
            if (bootName != null) {
                buffer.append(bootName)
                      .append('(')
                      .append(this.op)
                      .append(')');
            } else {
                buffer.append(this.op);
            }

            buffer.append("\nhtype=");

            final Object htypeName = _HTYPE_NAMES.get(this.htype);
            if (htypeName != null) {
                buffer.append(htypeName)
                      .append('(')
                      .append(this.htype)
                      .append(')');
            } else {
                buffer.append(this.htype);
            }

            buffer.append("\nhlen=")
                  .append(this.hlen)
                  .append("\nhops=")
                  .append(this.hops)
                  .append("\nxid=0x");
            appendHex(buffer, this.xid);
            buffer.append("\nsecs=")
                  .append(this.secs)
                  .append("\nflags=0x")
                  .append(Integer.toHexString(this.flags))
                  .append("\nciaddr=");
            appendHostAddress(buffer, InetAddress.getByAddress(this.ciaddr));
            buffer.append("\nyiaddr=");
            appendHostAddress(buffer, InetAddress.getByAddress(this.yiaddr));
            buffer.append("\nsiaddr=");
            appendHostAddress(buffer, InetAddress.getByAddress(this.siaddr));
            buffer.append("\ngiaddr=");
            appendHostAddress(buffer, InetAddress.getByAddress(this.giaddr));
            buffer.append("\nchaddr=0x");
            this.appendChaddrAsHex(buffer);
            buffer.append("\nsname=")
                  .append(this.getSname())
                  .append("\nfile=")
                  .append(this.getFile());

            if (this.isDhcp) {
                buffer.append("\nOptions follows:");

                // parse options in creation order (LinkedHashMap)
                for (DHCPOption opt : this.getOptionsCollection()) {
                    buffer.append('\n');
                    opt.append(buffer);
                }
            }

            // padding
            buffer.append("\npadding[")
                  .append(this.padding.length)
                  .append("]=");
            appendHex(buffer, this.padding);
        } catch (Exception e) {
            // what to do ???
        }

        return buffer.toString();
    }

    // ========================================================================
    // getters and setters

    /**
     * Returns the comment associated to this packet.
     *
     * <p>This field can be used freely and has no influence on the real network datagram.
     * It can be used to store a transaction number or any other information
     *
     * @return the _comment field.
     */
    public String getComment() {
        return this.comment;
    }
    /**
     * Sets the comment associated to this packet.
     *
     * <p>This field can be used freely and has no influence on the real network datagram.
     * It can be used to store a transaction number or any other information
     *
     * @param comment The comment to set.
     */
    public void setComment(String comment) {
        this.comment = comment;
    }
    /**
     * Returns the chaddr field (Client hardware address - typically MAC address).
     *
     * <p>Returns the byte[16] raw buffer. Only the first <tt>hlen</tt> bytes are valid.
     *
     * @return the chaddr field.
     */
    public byte[] getChaddr() {
        return this.chaddr.clone();
    }

    /**
     * Appends the chaddr field (Client hardware address - typically MAC address) as
     * a hex string to this string buffer.
     *
     * <p>Only first <tt>hlen</tt> bytes are appended, as uppercase hex string.
     *
     * @param buffer this string buffer
     * @return the string buffer.
     */
    private StringBuilder appendChaddrAsHex(StringBuilder buffer) {
        appendHex(buffer, this.chaddr, 0, this.hlen & 0xFF);
        return buffer;
    }
    
    /**
     * Return the hardware address (@MAC) as an <tt>HardwareAddress</tt> object.
     * 
     * @return the <tt>HardwareAddress</tt> object
     */
    public HardwareAddress getHardwareAddress() {
    	int len = this.hlen & 0xff;
    	if (len > 16) {
    		len = 16;
    	}
    	byte[] buf = new byte[len];
    	System.arraycopy(this.chaddr, 0, buf, 0, len);
    	return new HardwareAddress(this.htype, buf);
    }

    /**
     * Returns the chaddr field (Client hardware address - typically MAC address) as 
     * a hex string.
     *
     * <p>Only first <tt>hlen</tt> bytes are printed, as uppercase hex string.
     *
     * @return the chaddr field as hex string.
     */
    public String getChaddrAsHex() {
        return this.appendChaddrAsHex(new StringBuilder(this.hlen & 0xFF)).toString();
    }
    /**
     * Sets the chaddr field (Client hardware address - typically MAC address).
     *
     * <p>The buffer length should be between 0 and 16, otherwise an
     * <tt>IllegalArgumentException</tt> is thrown.
     *
     * <p>If chaddr is null, the field is filled with zeros.
     *
     * @param chaddr The chaddr to set.
     * @throws IllegalArgumentException chaddr buffer is longer than 16 bytes.
     */
    public void setChaddr(byte[] chaddr) {
        if (chaddr != null) {
            if (chaddr.length > this.chaddr.length) {
                throw new IllegalArgumentException("chaddr is too long: " + chaddr.length +
                                                   ", max is: " + this.chaddr.length);
            }
            Arrays.fill(this.chaddr, (byte) 0);
            System.arraycopy(chaddr, 0, this.chaddr, 0, chaddr.length);
        } else {
            Arrays.fill(this.chaddr, (byte) 0);
        }
    }
    /**
     * Sets the chaddr field - from an hex String.
     * 
     * @param hex the chaddr in hex format
     */
    public void setChaddrHex(String hex) {
        this.setChaddr(hex2Bytes(hex));
    }
    /**
     * Returns the ciaddr field (Client IP Address).
     * 
     * @return the ciaddr field converted to <tt>InetAddress</tt> object.
     */
    public InetAddress getCiaddr() {
        try {
            return InetAddress.getByAddress(this.getCiaddrRaw());
        } catch (UnknownHostException e) {
            logger.log(Level.SEVERE, "Unexpected UnknownHostException", e);
            return null;    // normaly impossible
        }
    }

    /**
     * Returns the ciaddr field (Client IP Address).
     *
     * <p>This is the low-level maximum performance getter for this field.
     *
     * @return Returns the ciaddr as raw byte[4].
     */
    public byte[] getCiaddrRaw() {
        return this.ciaddr.clone();
    }

    /**
     * Sets the ciaddr field (Client IP Address).
     *
     * <p>Ths <tt>ciaddr</tt> field must be of <tt>Inet4Address</tt> class or
     * an <tt>IllegalArgumentException</tt> is thrown.
     *
     * @param ciaddr The ciaddr to set.
     */
    public void setCiaddr(InetAddress ciaddr) {
        if (!(ciaddr instanceof Inet4Address)) {
            throw new IllegalArgumentException("Inet4Address required");
        }
        this.setCiaddrRaw(ciaddr.getAddress());
    }
    /**
     * Sets the ciaddr field (Client IP Address).
     *
     * @param ciaddr The ciaddr to set.
     * @throws UnknownHostException
     */
    public void setCiaddr(String ciaddr) throws UnknownHostException {
        this.setCiaddr(InetAddress.getByName(ciaddr));
    }
    /**
     * Sets the ciaddr field (Client IP Address).
     *
     * <p><tt>ciaddr</tt> must be a 4 bytes array, or an <tt>IllegalArgumentException</tt>
     * is thrown.
     *
     * <p>This is the low-level maximum performance setter for this field.
     * The array is internally copied so any further modification to <tt>ciaddr</tt>
     * parameter has no side effect.
     *
     * @param ciaddr The ciaddr to set.
     */
    public void setCiaddrRaw(byte[] ciaddr) {
        if (ciaddr.length != 4) {
            throw new IllegalArgumentException("4-byte array required");
        }
        System.arraycopy(ciaddr, 0, this.ciaddr, 0, 4);
    }
    /**
     * Returns the file field (Boot File Name).
     *
     * <p>Returns the raw byte[128] buffer, containing a null terminated string.
     *
     * <p>This is the low-level maximum performance getter for this field.
     *
     * @return the file field.
     */
    public byte[] getFileRaw() {
        return this.file.clone();
    }

    /**
     * Returns the file field (Boot File Name) as String.
     *
     * @return the file converted to a String (transparent encoding).
     */
    public String getFile() {
        return bytesToString(this.getFileRaw());
    }
    /**
     * Sets the file field (Boot File Name) as String.
     *
     * <p>The string is first converted to a byte[] array using transparent
     * encoding. If the resulting buffer size is > 128, an <tt>IllegalArgumentException</tt>
     * is thrown.
     *
     * <p>If <tt>file</tt> parameter is null, the buffer is filled with zeros.
     *
     * @param file The file field to set.
     * @throws IllegalArgumentException string too long
     */
    public void setFile(String file) {
        this.setFileRaw(stringToBytes(file));
    }

    /**
     * Sets the file field (Boot File Name) as String.
     *
     * <p>If the buffer size is > 128, an <tt>IllegalArgumentException</tt>
     * is thrown.
     *
     * <p>If <tt>file</tt> parameter is null, the buffer is filled with zeros.
     *
     * <p>This is the low-level maximum performance setter for this field.
     *
     * @param file The file field to set.
     * @throws IllegalArgumentException string too long
     */
    public void setFileRaw(byte[] file) {
        if (file != null) {
            if (file.length > this.file.length) {
                throw new IllegalArgumentException("File is too long:" + file.length + " max is:" + this.file.length);
            }
            Arrays.fill(this.file, (byte) 0);
            System.arraycopy(file, 0, this.file, 0, file.length);
        } else {
            Arrays.fill(this.file, (byte) 0);
        }
    }

    /**
     * Returns the flags field.
     *
     * @return the flags field.
     */
    public short getFlags() {
        return this.flags;
    }

    /**
     * Sets the flags field.
     *
     * @param flags The flags field to set.
     */
    public void setFlags(short flags) {
        this.flags = flags;