io.undertow.protocols.http2.HpackEncoder Maven / Gradle / Ivy
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* 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);
}
}
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