org.bitcoinj.script.ScriptChunk Maven / Gradle / Ivy
/*
* Copyright 2013 Google Inc.
* Copyright 2014 Andreas Schildbach
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.bitcoinj.script;
import org.bitcoinj.core.Utils;
import com.google.common.base.Objects;
import javax.annotation.Nullable;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import static com.google.common.base.Preconditions.checkState;
import static org.bitcoinj.script.ScriptOpCodes.*;
/**
* A script element that is either a data push (signature, pubkey, etc) or a non-push (logic, numeric, etc) operation.
*/
public class ScriptChunk {
/** Operation to be executed. Opcodes are defined in {@link ScriptOpCodes}. */
public final int opcode;
/**
* For push operations, this is the vector to be pushed on the stack. For {@link ScriptOpCodes#OP_0}, the vector is
* empty. Null for non-push operations.
*/
@Nullable
public final byte[] data;
private int startLocationInProgram;
public ScriptChunk(int opcode, @Nullable byte[] data) {
this(opcode, data, -1);
}
public ScriptChunk(int opcode, @Nullable byte[] data, int startLocationInProgram) {
this.opcode = opcode;
this.data = data;
this.startLocationInProgram = startLocationInProgram;
}
public boolean equalsOpCode(int opcode) {
return opcode == this.opcode;
}
/**
* If this chunk is a single byte of non-pushdata content (could be OP_RESERVED or some invalid Opcode)
*/
public boolean isOpCode() {
return opcode > OP_PUSHDATA4;
}
/**
* Returns true if this chunk is pushdata content, including the single-byte pushdatas.
*/
public boolean isPushData() {
return opcode <= OP_16;
}
public int getStartLocationInProgram() {
checkState(startLocationInProgram >= 0);
return startLocationInProgram;
}
/** If this chunk is an OP_N opcode returns the equivalent integer value. */
public int decodeOpN() {
checkState(isOpCode());
return Script.decodeFromOpN(opcode);
}
/**
* Called on a pushdata chunk, returns true if it uses the smallest possible way (according to BIP62) to push the data.
*/
public boolean isShortestPossiblePushData() {
checkState(isPushData());
if (data == null)
return true; // OP_N
if (data.length == 0)
return opcode == OP_0;
if (data.length == 1) {
byte b = data[0];
if (b >= 0x01 && b <= 0x10)
return opcode == OP_1 + b - 1;
if ((b & 0xFF) == 0x81)
return opcode == OP_1NEGATE;
}
if (data.length < OP_PUSHDATA1)
return opcode == data.length;
if (data.length < 256)
return opcode == OP_PUSHDATA1;
if (data.length < 65536)
return opcode == OP_PUSHDATA2;
// can never be used, but implemented for completeness
return opcode == OP_PUSHDATA4;
}
public void write(OutputStream stream) throws IOException {
if (isOpCode()) {
checkState(data == null);
stream.write(opcode);
} else if (data != null) {
if (opcode < OP_PUSHDATA1) {
checkState(data.length == opcode);
stream.write(opcode);
} else if (opcode == OP_PUSHDATA1) {
checkState(data.length <= 0xFF);
stream.write(OP_PUSHDATA1);
stream.write(data.length);
} else if (opcode == OP_PUSHDATA2) {
checkState(data.length <= 0xFFFF);
stream.write(OP_PUSHDATA2);
Utils.uint16ToByteStreamLE(data.length, stream);
} else if (opcode == OP_PUSHDATA4) {
checkState(data.length <= Script.MAX_SCRIPT_ELEMENT_SIZE);
stream.write(OP_PUSHDATA4);
Utils.uint32ToByteStreamLE(data.length, stream);
} else {
throw new RuntimeException("Unimplemented");
}
stream.write(data);
} else {
stream.write(opcode); // smallNum
}
}
public byte[] toByteArray() {
ByteArrayOutputStream stream = new ByteArrayOutputStream();
try {
write(stream);
} catch (IOException e) {
// Should not happen as ByteArrayOutputStream does not throw IOException on write
throw new RuntimeException(e);
}
return stream.toByteArray();
}
@Override
public String toString() {
StringBuilder buf = new StringBuilder();
if (isOpCode()) {
buf.append(getOpCodeName(opcode));
} else if (data != null) {
// Data chunk
buf.append(getPushDataName(opcode)).append("[").append(Utils.HEX.encode(data)).append("]");
} else {
// Small num
buf.append(Script.decodeFromOpN(opcode));
}
return buf.toString();
}
@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
ScriptChunk other = (ScriptChunk) o;
return opcode == other.opcode && startLocationInProgram == other.startLocationInProgram
&& Arrays.equals(data, other.data);
}
@Override
public int hashCode() {
return Objects.hashCode(opcode, startLocationInProgram, Arrays.hashCode(data));
}
}