io.undertow.protocols.http2.HpackEncoder Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* JBoss, Home of Professional Open Source.
* Copyright 2014 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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 io.undertow.protocols.http2;
import io.undertow.util.HeaderMap;
import io.undertow.util.HeaderValues;
import io.undertow.util.Headers;
import io.undertow.util.HttpString;
import java.nio.ByteBuffer;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import static io.undertow.protocols.http2.Hpack.HeaderField;
import static io.undertow.protocols.http2.Hpack.STATIC_TABLE;
import static io.undertow.protocols.http2.Hpack.STATIC_TABLE_LENGTH;
import static io.undertow.protocols.http2.Hpack.encodeInteger;
/**
* Encoder for HPACK frames.
*
* @author Stuart Douglas
*/
public class HpackEncoder {
private static final Set SKIP;
static {
Set set = new HashSet<>();
set.add(Headers.CONNECTION);
set.add(Headers.TRANSFER_ENCODING);
set.add(Headers.KEEP_ALIVE);
set.add(Headers.UPGRADE);
SKIP = Collections.unmodifiableSet(set);
}
public static final HpackHeaderFunction DEFAULT_HEADER_FUNCTION = new HpackHeaderFunction() {
@Override
public boolean shouldUseIndexing(HttpString headerName, String value) {
//content length and date change all the time
//no need to index them, or they will churn the table
return !headerName.equals(Headers.CONTENT_LENGTH) && !headerName.equals(Headers.DATE);
}
@Override
public boolean shouldUseHuffman(HttpString header, String value) {
return value.length() > 10; //TODO: figure out a good value for this
}
@Override
public boolean shouldUseHuffman(HttpString header) {
return header.length() > 10; //TODO: figure out a good value for this
}
};
private long headersIterator = -1;
private boolean firstPass = true;
private HeaderMap currentHeaders;
private int entryPositionCounter;
private int newMaxHeaderSize = -1; //if the max header size has been changed
private int minNewMaxHeaderSize = -1; //records the smallest value of newMaxHeaderSize, as per section 4.1
private static final Map ENCODING_STATIC_TABLE;
private final Deque evictionQueue = new ArrayDeque<>();
private final Map> dynamicTable = new HashMap<>();
private byte[] overflowData;
private int overflowPos;
private int overflowLength;
static {
Map map = new HashMap<>();
for (int i = 1; i < STATIC_TABLE.length; ++i) {
HeaderField m = STATIC_TABLE[i];
TableEntry[] existing = map.get(m.name);
if (existing == null) {
map.put(m.name, new TableEntry[]{new TableEntry(m.name, m.value, i)});
} else {
TableEntry[] newEntry = new TableEntry[existing.length + 1];
System.arraycopy(existing, 0, newEntry, 0, existing.length);
newEntry[existing.length] = new TableEntry(m.name, m.value, i);
map.put(m.name, newEntry);
}
}
ENCODING_STATIC_TABLE = Collections.unmodifiableMap(map);
}
/**
* The maximum table size
*/
private int maxTableSize;
/**
* The current table size
*/
private int currentTableSize;
private final HpackHeaderFunction hpackHeaderFunction;
public HpackEncoder(int maxTableSize, HpackHeaderFunction headerFunction) {
this.maxTableSize = maxTableSize;
this.hpackHeaderFunction = headerFunction;
}
public HpackEncoder(int maxTableSize) {
this(maxTableSize, DEFAULT_HEADER_FUNCTION);
}
/**
* Encodes the headers into a buffer.
*
* @param headers
* @param target
*/
public State encode(HeaderMap headers, ByteBuffer target) {
if(overflowData != null) {
for(int i = overflowPos; i < overflowLength; ++i) {
if(!target.hasRemaining()) {
overflowPos = i;
return State.OVERFLOW;
}
target.put(overflowData[i]);
}
overflowData = null;
}
long it = headersIterator;
if (headersIterator == -1) {
handleTableSizeChange(target);
//new headers map
it = headers.fastIterate();
currentHeaders = headers;
} else {
if (headers != currentHeaders) {
throw new IllegalStateException();
}
it = headers.fiNext(it);
}
while (it != -1) {
HeaderValues values = headers.fiCurrent(it);
boolean skip = false;
if (firstPass) {
if (values.getHeaderName().byteAt(0) != ':') {
skip = true;
}
} else {
if (values.getHeaderName().byteAt(0) == ':') {
skip = true;
}
}
if(SKIP.contains(values.getHeaderName())) {
//ignore connection specific headers
skip = true;
}
if (!skip) {
for (int i = 0; i < values.size(); ++i) {
HttpString headerName = values.getHeaderName();
int required = 11 + headerName.length(); //we use 11 to make sure we have enough room for the variable length itegers
String val = values.get(i);
for(int v = 0; v < val.length(); ++v) {
char c = val.charAt(v);
if(c == '\r' || c == '\n') {
val = val.replace('\r', ' ').replace('\n', ' ');
break;
}
}
TableEntry tableEntry = findInTable(headerName, val);
required += (1 + val.length());
boolean overflowing = false;
ByteBuffer current = target;
if (current.remaining() < required) {
overflowing = true;
current = ByteBuffer.wrap(overflowData = new byte[required]);
overflowPos = 0;
}
boolean canIndex = hpackHeaderFunction.shouldUseIndexing(headerName, val) && (headerName.length() + val.length() + 32) < maxTableSize; //only index if it will fit
if (tableEntry == null && canIndex) {
//add the entry to the dynamic table
current.put((byte) (1 << 6));
writeHuffmanEncodableName(current, headerName);
writeHuffmanEncodableValue(current, headerName, val);
addToDynamicTable(headerName, val);
} else if (tableEntry == null) {
//literal never indexed
current.put((byte) (1 << 4));
writeHuffmanEncodableName(current, headerName);
writeHuffmanEncodableValue(current, headerName, val);
} else {
//so we know something is already in the table
if (val.equals(tableEntry.value)) {
//the whole thing is in the table
current.put((byte) (1 << 7));
encodeInteger(current, tableEntry.getPosition(), 7);
} else {
if (canIndex) {
//add the entry to the dynamic table
current.put((byte) (1 << 6));
encodeInteger(current, tableEntry.getPosition(), 6);
writeHuffmanEncodableValue(current, headerName, val);
addToDynamicTable(headerName, val);
} else {
current.put((byte) (1 << 4));
encodeInteger(current, tableEntry.getPosition(), 4);
writeHuffmanEncodableValue(current, headerName, val);
}
}
}
if(overflowing) {
this.headersIterator = it;
this.overflowLength = current.position();
return State.OVERFLOW;
}
}
}
it = headers.fiNext(it);
if (it == -1 && firstPass) {
firstPass = false;
it = headers.fastIterate();
}
}
headersIterator = -1;
firstPass = true;
return State.COMPLETE;
}
private void writeHuffmanEncodableName(ByteBuffer target, HttpString headerName) {
if (hpackHeaderFunction.shouldUseHuffman(headerName)) {
if(HPackHuffman.encode(target, headerName.toString(), true)) {
return;
}
}
target.put((byte) 0); //to use encodeInteger we need to place the first byte in the buffer.
encodeInteger(target, headerName.length(), 7);
for (int j = 0; j < headerName.length(); ++j) {
target.put(Hpack.toLower(headerName.byteAt(j)));
}
}
private void writeHuffmanEncodableValue(ByteBuffer target, HttpString headerName, String val) {
if (hpackHeaderFunction.shouldUseHuffman(headerName, val)) {
if (!HPackHuffman.encode(target, val, false)) {
writeValueString(target, val);
}
} else {
writeValueString(target, val);
}
}
private void writeValueString(ByteBuffer target, String val) {
target.put((byte) 0); //to use encodeInteger we need to place the first byte in the buffer.
encodeInteger(target, val.length(), 7);
for (int j = 0; j < val.length(); ++j) {
target.put((byte) val.charAt(j));
}
}
private void addToDynamicTable(HttpString headerName, String val) {
int pos = entryPositionCounter++;
DynamicTableEntry d = new DynamicTableEntry(headerName, val, -pos);
List existing = dynamicTable.get(headerName);
if (existing == null) {
dynamicTable.put(headerName, existing = new ArrayList<>(1));
}
existing.add(d);
evictionQueue.add(d);
currentTableSize += d.size;
runEvictionIfRequired();
if (entryPositionCounter == Integer.MAX_VALUE) {
//prevent rollover
preventPositionRollover();
}
}
private void preventPositionRollover() {
//if the position counter is about to roll over we iterate all the table entries
//and set their position to their actual position
for (Map.Entry> entry : dynamicTable.entrySet()) {
for (TableEntry t : entry.getValue()) {
t.position = t.getPosition();
}
}
entryPositionCounter = 0;
}
private void runEvictionIfRequired() {
while (currentTableSize > maxTableSize) {
TableEntry next = evictionQueue.poll();
if (next == null) {
return;
}
currentTableSize -= next.size;
List list = dynamicTable.get(next.name);
list.remove(next);
if (list.isEmpty()) {
dynamicTable.remove(next.name);
}
}
}
private TableEntry findInTable(HttpString headerName, String value) {
TableEntry[] staticTable = ENCODING_STATIC_TABLE.get(headerName);
if (staticTable != null) {
for (TableEntry st : staticTable) {
if (st.value != null && st.value.equals(value)) { //todo: some form of lookup?
return st;
}
}
}
List dynamic = dynamicTable.get(headerName);
if (dynamic != null) {
for (int i = 0; i < dynamic.size(); ++i) {
TableEntry st = dynamic.get(i);
if (st.value.equals(value)) { //todo: some form of lookup?
return st;
}
}
}
if (staticTable != null) {
return staticTable[0];
}
return null;
}
public void setMaxTableSize(int newSize) {
this.newMaxHeaderSize = newSize;
if (minNewMaxHeaderSize == -1) {
minNewMaxHeaderSize = newSize;
} else {
minNewMaxHeaderSize = Math.min(newSize, minNewMaxHeaderSize);
}
}
private void handleTableSizeChange(ByteBuffer target) {
if (newMaxHeaderSize == -1) {
return;
}
if (minNewMaxHeaderSize != newMaxHeaderSize) {
target.put((byte) (1 << 5));
encodeInteger(target, minNewMaxHeaderSize, 5);
}
target.put((byte) (1 << 5));
encodeInteger(target, newMaxHeaderSize, 5);
maxTableSize = newMaxHeaderSize;
runEvictionIfRequired();
newMaxHeaderSize = -1;
minNewMaxHeaderSize = -1;
}
public enum State {
COMPLETE,
OVERFLOW,
}
static class TableEntry {
final HttpString name;
final String value;
final int size;
int position;
TableEntry(HttpString name, String value, int position) {
this.name = name;
this.value = value;
this.position = position;
if (value != null) {
this.size = 32 + name.length() + value.length();
} else {
this.size = -1;
}
}
public int getPosition() {
return position;
}
}
class DynamicTableEntry extends TableEntry {
DynamicTableEntry(HttpString name, String value, int position) {
super(name, value, position);
}
@Override
public int getPosition() {
return super.getPosition() + entryPositionCounter + STATIC_TABLE_LENGTH;
}
}
public interface HpackHeaderFunction {
boolean shouldUseIndexing(HttpString header, String value);
/**
* Returns true if huffman encoding should be used on the header value
*
* @param header The header name
* @param value The header value to be encoded
* @return true if the value should be encoded
*/
boolean shouldUseHuffman(HttpString header, String value);
/**
* Returns true if huffman encoding should be used on the header name
*
* @param header The header name to be encoded
* @return true if the value should be encoded
*/
boolean shouldUseHuffman(HttpString header);
}
}