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Diffstat (limited to 'src/org/xbill/DNS/DNSOutput.java')
| -rw-r--r-- | src/org/xbill/DNS/DNSOutput.java | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/src/org/xbill/DNS/DNSOutput.java b/src/org/xbill/DNS/DNSOutput.java new file mode 100644 index 0000000..29a8f68 --- /dev/null +++ b/src/org/xbill/DNS/DNSOutput.java @@ -0,0 +1,203 @@ +// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org) + +package org.xbill.DNS; + +/** + * A class for rendering DNS messages. + * + * @author Brian Wellington + */ + + +public class DNSOutput { + +private byte [] array; +private int pos; +private int saved_pos; + +/** + * Create a new DNSOutput with a specified size. + * @param size The initial size + */ +public +DNSOutput(int size) { + array = new byte[size]; + pos = 0; + saved_pos = -1; +} + +/** + * Create a new DNSOutput + */ +public +DNSOutput() { + this(32); +} + +/** + * Returns the current position. + */ +public int +current() { + return pos; +} + +private void +check(long val, int bits) { + long max = 1; + max <<= bits; + if (val < 0 || val > max) { + throw new IllegalArgumentException(val + " out of range for " + + bits + " bit value"); + } +} + +private void +need(int n) { + if (array.length - pos >= n) { + return; + } + int newsize = array.length * 2; + if (newsize < pos + n) { + newsize = pos + n; + } + byte [] newarray = new byte[newsize]; + System.arraycopy(array, 0, newarray, 0, pos); + array = newarray; +} + +/** + * Resets the current position of the output stream to the specified index. + * @param index The new current position. + * @throws IllegalArgumentException The index is not within the output. + */ +public void +jump(int index) { + if (index > pos) { + throw new IllegalArgumentException("cannot jump past " + + "end of data"); + } + pos = index; +} + +/** + * Saves the current state of the output stream. + * @throws IllegalArgumentException The index is not within the output. + */ +public void +save() { + saved_pos = pos; +} + +/** + * Restores the input stream to its state before the call to {@link #save}. + */ +public void +restore() { + if (saved_pos < 0) { + throw new IllegalStateException("no previous state"); + } + pos = saved_pos; + saved_pos = -1; +} + +/** + * Writes an unsigned 8 bit value to the stream. + * @param val The value to be written + */ +public void +writeU8(int val) { + check(val, 8); + need(1); + array[pos++] = (byte)(val & 0xFF); +} + +/** + * Writes an unsigned 16 bit value to the stream. + * @param val The value to be written + */ +public void +writeU16(int val) { + check(val, 16); + need(2); + array[pos++] = (byte)((val >>> 8) & 0xFF); + array[pos++] = (byte)(val & 0xFF); +} + +/** + * Writes an unsigned 16 bit value to the specified position in the stream. + * @param val The value to be written + * @param where The position to write the value. + */ +public void +writeU16At(int val, int where) { + check(val, 16); + if (where > pos - 2) + throw new IllegalArgumentException("cannot write past " + + "end of data"); + array[where++] = (byte)((val >>> 8) & 0xFF); + array[where++] = (byte)(val & 0xFF); +} + +/** + * Writes an unsigned 32 bit value to the stream. + * @param val The value to be written + */ +public void +writeU32(long val) { + check(val, 32); + need(4); + array[pos++] = (byte)((val >>> 24) & 0xFF); + array[pos++] = (byte)((val >>> 16) & 0xFF); + array[pos++] = (byte)((val >>> 8) & 0xFF); + array[pos++] = (byte)(val & 0xFF); +} + +/** + * Writes a byte array to the stream. + * @param b The array to write. + * @param off The offset of the array to start copying data from. + * @param len The number of bytes to write. + */ +public void +writeByteArray(byte [] b, int off, int len) { + need(len); + System.arraycopy(b, off, array, pos, len); + pos += len; +} + +/** + * Writes a byte array to the stream. + * @param b The array to write. + */ +public void +writeByteArray(byte [] b) { + writeByteArray(b, 0, b.length); +} + +/** + * Writes a counted string from the stream. A counted string is a one byte + * value indicating string length, followed by bytes of data. + * @param s The string to write. + */ +public void +writeCountedString(byte [] s) { + if (s.length > 0xFF) { + throw new IllegalArgumentException("Invalid counted string"); + } + need(1 + s.length); + array[pos++] = (byte)(s.length & 0xFF); + writeByteArray(s, 0, s.length); +} + +/** + * Returns a byte array containing the current contents of the stream. + */ +public byte [] +toByteArray() { + byte [] out = new byte[pos]; + System.arraycopy(array, 0, out, 0, pos); + return out; +} + +} |