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Classes for converting to XRPL binary format
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package org.xrpl.xrpl4j.codec.binary.serdes;
/*-
* ========================LICENSE_START=================================
* xrpl4j :: binary-codec
* %%
* Copyright (C) 2020 - 2022 XRPL Foundation and its contributors
* %%
* 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.
* =========================LICENSE_END==================================
*/
import com.google.common.primitives.UnsignedLong;
import org.xrpl.xrpl4j.codec.addresses.ByteUtils;
import org.xrpl.xrpl4j.codec.addresses.UnsignedByte;
import org.xrpl.xrpl4j.codec.addresses.UnsignedByteArray;
import org.xrpl.xrpl4j.codec.binary.FieldHeader;
import org.xrpl.xrpl4j.codec.binary.definitions.DefinitionsService;
import org.xrpl.xrpl4j.codec.binary.definitions.FieldInstance;
import org.xrpl.xrpl4j.codec.binary.types.FieldWithValue;
import org.xrpl.xrpl4j.codec.binary.types.SerializedType;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
/**
* Parser for XRPL binary hex values.
*/
public class BinaryParser {
// max length that can be represented in a single byte per XRPL serialization restrictions
public static final int MAX_SINGLE_BYTE_LENGTH = 192;
// max length that can be represented in 2 bytes per XRPL serialization restrictions
public static final int MAX_DOUBLE_BYTE_LENGTH = 12481;
// max value that can be used in the second byte of a length field
public static final int MAX_SECOND_BYTE_VALUE = 240;
// max value that can be represented using one 8-bit byte
public static final int MAX_BYTE_VALUE = 256;
// max value that can be represented in using two 8-bit bytes
public static final int MAX_DOUBLE_BYTE_VALUE = 65536;
// 1 byte encodes to 2 characters in hex
private static final int BYTE_HEX_LENGTH = 2;
private final String hex;
private int cursor = 0;
public BinaryParser(String hex) {
this.hex = hex;
}
public UnsignedByte peek() {
return UnsignedByte.of(hex.substring(cursor, cursor + BYTE_HEX_LENGTH));
}
public void skip(int bytesToSkip) {
cursor += bytesToSkip * BYTE_HEX_LENGTH;
}
/**
* Read from this parser.
*
* @param bytesToRead An int representing the number of bytes to read.
*
* @return An {@link UnsignedByteArray}.
*/
public UnsignedByteArray read(int bytesToRead) {
if (cursor >= hex.length()) {
throw new IndexOutOfBoundsException("cursor moved past end of buffer");
}
List result = new ArrayList<>();
for (int i = 0; i < bytesToRead; i++) {
result.add(peek());
skip(1);
}
return new UnsignedByteArray(result);
}
public UnsignedLong readUInt8() {
return readUInt(1);
}
public UnsignedLong readUInt16() {
return readUInt(2);
}
public UnsignedLong readUInt32() {
return readUInt(4);
}
public UnsignedLong readUInt64() {
return readUInt(8);
}
public int size() {
return hex.length() / BYTE_HEX_LENGTH;
}
public boolean hasMore() {
return cursor < hex.length();
}
/**
* Reads the length of the variable length encoded bytes.
*
* @return The length of the variable length encoded bytes.
*/
public int readVariableLengthLength() {
int firstByte = this.readUInt8().intValue();
if (firstByte <= MAX_SINGLE_BYTE_LENGTH) {
return firstByte;
} else if (firstByte <= MAX_SECOND_BYTE_VALUE) {
int b2 = this.readUInt8().intValue();
return MAX_SECOND_BYTE_VALUE - 1 + (firstByte - MAX_SECOND_BYTE_VALUE - 1) * MAX_BYTE_VALUE + b2;
} else if (firstByte <= 254) {
int b2 = this.readUInt8().intValue();
int b3 = this.readUInt8().intValue();
return MAX_DOUBLE_BYTE_LENGTH + (firstByte - MAX_SECOND_BYTE_VALUE - 1) * MAX_DOUBLE_BYTE_VALUE +
b2 * MAX_BYTE_VALUE +
b3;
}
throw new Error("Invalid variable length indicator");
}
/**
* Reads the field ordinal from the BinaryParser.
*
* @return Field ordinal.
*/
public FieldHeader readFieldHeader() {
int type = this.readUInt8().intValue();
int nth = type & 15;
type >>= 4;
if (type == 0) {
type = this.readUInt8().intValue();
if (type == 0 || type < 16) {
throw new Error("Cannot read FieldOrdinal, type_code out of range");
}
}
if (nth == 0) {
nth = this.readUInt8().intValue();
if (nth == 0 || nth < 16) {
throw new Error("Cannot read FieldOrdinal, field_code out of range");
}
}
return FieldHeader.builder().fieldCode(nth).typeCode(type).build();
}
/**
* Read the field from the BinaryParser.
*
* @return The field represented by the bytes at the head of the BinaryParser.
*/
public Optional readField() {
FieldHeader header = readFieldHeader();
String fieldName = DefinitionsService.getInstance().getFieldName(header);
return DefinitionsService.getInstance().getFieldInstance(fieldName);
}
/**
* Read a given type from the BinaryParser.
*
* @param type The type that you want to read from the BinaryParser.
* @param A {@link SerializedType} to read as.
*
* @return The instance of the type read from the BinaryParser.
*/
public > T readType(Class type) {
try {
return type.getDeclaredConstructor().newInstance().fromParser(this);
} catch (Exception e) {
throw new RuntimeException("could not instantiate field of type " + type.getName(), e);
}
}
/**
* Get the type associated with a given field.
*
* @param field The field that you wan to get the type of.
*
* @return The type associated with the given field.
*/
public SerializedType typeForField(FieldInstance field) {
return SerializedType.getTypeByName(field.type());
}
/**
* Read value of the type specified by field from the BinaryParser.
*
* @param field The field that you want to get the associated value for.
*
* @return The value associated with the given field.
*/
public SerializedType readFieldValue(final FieldInstance field) {
Objects.requireNonNull(field);
SerializedType type = this.typeForField(field);
if (type == null) {
throw new IllegalArgumentException("unsupported type " + type);
}
try {
if (field.isVariableLengthEncoded()) {
int sizeHint = this.readVariableLengthLength();
return type.fromParser(this, sizeHint);
} else {
return type.fromParser(this);
}
} catch (Exception e) {
throw new RuntimeException("could not instantiate field of type " + field.name(), e);
}
}
/**
* Get the next field and value from the BinaryParser.
*
* @return The field and value.
*/
public Optional readFieldAndValue() {
return this.readField()
.map(field ->
FieldWithValue.builder()
.field(field)
.value(this.readFieldValue(field))
.build());
}
private UnsignedLong readUInt(int bytes) {
return ByteUtils.toUnsignedLong(read(bytes));
}
}