/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you 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.netty.handler.codec.http;
import static io.netty.util.AsciiString.containsContentEqualsIgnoreCase;
import static io.netty.util.AsciiString.containsAllContentEqualsIgnoreCase;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.ReferenceCounted;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import static io.netty.handler.codec.http.HttpResponseStatus.SWITCHING_PROTOCOLS;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
import static io.netty.util.internal.ObjectUtil.checkNotNull;
/**
* A server-side handler that receives HTTP requests and optionally performs a protocol switch if
* the requested protocol is supported. Once an upgrade is performed, this handler removes itself
* from the pipeline.
*/
public class HttpServerUpgradeHandler extends HttpObjectAggregator {
/**
* The source codec that is used in the pipeline initially.
*/
public interface SourceCodec {
/**
* Removes this codec (i.e. all associated handlers) from the pipeline.
*/
void upgradeFrom(ChannelHandlerContext ctx);
}
/**
* A codec that the source can be upgraded to.
*/
public interface UpgradeCodec {
/**
* Gets all protocol-specific headers required by this protocol for a successful upgrade.
* Any supplied header will be required to appear in the {@link HttpHeaderNames#CONNECTION} header as well.
*/
Collection<CharSequence> requiredUpgradeHeaders();
/**
* Prepares the {@code upgradeHeaders} for a protocol update based upon the contents of {@code upgradeRequest}.
* This method returns a boolean value to proceed or abort the upgrade in progress. If {@code false} is
* returned, the upgrade is aborted and the {@code upgradeRequest} will be passed through the inbound pipeline
* as if no upgrade was performed. If {@code true} is returned, the upgrade will proceed to the next
* step which invokes {@link #upgradeTo}. When returning {@code true}, you can add headers to
* the {@code upgradeHeaders} so that they are added to the 101 Switching protocols response.
*/
boolean prepareUpgradeResponse(ChannelHandlerContext ctx, FullHttpRequest upgradeRequest,
HttpHeaders upgradeHeaders);
/**
* Performs an HTTP protocol upgrade from the source codec. This method is responsible for
* adding all handlers required for the new protocol.
*
* @param ctx the context for the current handler.
* @param upgradeRequest the request that triggered the upgrade to this protocol.
*/
void upgradeTo(ChannelHandlerContext ctx, FullHttpRequest upgradeRequest);
}
/**
* Creates a new {@link UpgradeCodec} for the requested protocol name.
*/
public interface UpgradeCodecFactory {
/**
* Invoked by {@link HttpServerUpgradeHandler} for all the requested protocol names in the order of
* the client preference. The first non-{@code null} {@link UpgradeCodec} returned by this method
* will be selected.
*
* @return a new {@link UpgradeCodec}, or {@code null} if the specified protocol name is not supported
*/
UpgradeCodec newUpgradeCodec(CharSequence protocol);
}
/**
* User event that is fired to notify about the completion of an HTTP upgrade
* to another protocol. Contains the original upgrade request so that the response
* (if required) can be sent using the new protocol.
*/
public static final class UpgradeEvent implements ReferenceCounted {
private final CharSequence protocol;
private final FullHttpRequest upgradeRequest;
UpgradeEvent(CharSequence protocol, FullHttpRequest upgradeRequest) {
this.protocol = protocol;
this.upgradeRequest = upgradeRequest;
}
/**
* The protocol that the channel has been upgraded to.
*/
public CharSequence protocol() {
return protocol;
}
/**
* Gets the request that triggered the protocol upgrade.
*/
public FullHttpRequest upgradeRequest() {
return upgradeRequest;
}
@Override
public int refCnt() {
return upgradeRequest.refCnt();
}
@Override
public UpgradeEvent retain() {
upgradeRequest.retain();
return this;
}
@Override
public UpgradeEvent retain(int increment) {
upgradeRequest.retain(increment);
return this;
}
@Override
public UpgradeEvent touch() {
upgradeRequest.touch();
return this;
}
@Override
public UpgradeEvent touch(Object hint) {
upgradeRequest.touch(hint);
return this;
}
@Override
public boolean release() {
return upgradeRequest.release();
}
@Override
public boolean release(int decrement) {
return upgradeRequest.release(decrement);
}
@Override
public String toString() {
return "UpgradeEvent [protocol=" + protocol + ", upgradeRequest=" + upgradeRequest + ']';
}
}
private final SourceCodec sourceCodec;
private final UpgradeCodecFactory upgradeCodecFactory;
private boolean handlingUpgrade;
/**
* Constructs the upgrader with the supported codecs.
* <p>
* The handler instantiated by this constructor will reject an upgrade request with non-empty content.
* It should not be a concern because an upgrade request is most likely a GET request.
* If you have a client that sends a non-GET upgrade request, please consider using
* {@link #HttpServerUpgradeHandler(SourceCodec, UpgradeCodecFactory, int)} to specify the maximum
* length of the content of an upgrade request.
* </p>
*
* @param sourceCodec the codec that is being used initially
* @param upgradeCodecFactory the factory that creates a new upgrade codec
* for one of the requested upgrade protocols
*/
public HttpServerUpgradeHandler(SourceCodec sourceCodec, UpgradeCodecFactory upgradeCodecFactory) {
this(sourceCodec, upgradeCodecFactory, 0);
}
/**
* Constructs the upgrader with the supported codecs.
*
* @param sourceCodec the codec that is being used initially
* @param upgradeCodecFactory the factory that creates a new upgrade codec
* for one of the requested upgrade protocols
* @param maxContentLength the maximum length of the content of an upgrade request
*/
public HttpServerUpgradeHandler(
SourceCodec sourceCodec, UpgradeCodecFactory upgradeCodecFactory, int maxContentLength) {
super(maxContentLength);
this.sourceCodec = checkNotNull(sourceCodec, "sourceCodec");
this.upgradeCodecFactory = checkNotNull(upgradeCodecFactory, "upgradeCodecFactory");
}
@Override
protected void decode(ChannelHandlerContext ctx, HttpObject msg, List<Object> out)
throws Exception {
// Determine if we're already handling an upgrade request or just starting a new one.
handlingUpgrade |= isUpgradeRequest(msg);
if (!handlingUpgrade) {
// Not handling an upgrade request, just pass it to the next handler.
ReferenceCountUtil.retain(msg);
out.add(msg);
return;
}
FullHttpRequest fullRequest;
if (msg instanceof FullHttpRequest) {
fullRequest = (FullHttpRequest) msg;
ReferenceCountUtil.retain(msg);
out.add(msg);
} else {
// Call the base class to handle the aggregation of the full request.
super.decode(ctx, msg, out);
if (out.isEmpty()) {
// The full request hasn't been created yet, still awaiting more data.
return;
}
// Finished aggregating the full request, get it from the output list.
assert out.size() == 1;
handlingUpgrade = false;
fullRequest = (FullHttpRequest) out.get(0);
}
if (upgrade(ctx, fullRequest)) {
// The upgrade was successful, remove the message from the output list
// so that it's not propagated to the next handler. This request will
// be propagated as a user event instead.
out.clear();
}
// The upgrade did not succeed, just allow the full request to propagate to the
// next handler.
}
/**
* Determines whether or not the message is an HTTP upgrade request.
*/
private static boolean isUpgradeRequest(HttpObject msg) {
return msg instanceof HttpRequest && ((HttpRequest) msg).headers().get(HttpHeaderNames.UPGRADE) != null;
}
/**
* Attempts to upgrade to the protocol(s) identified by the {@link HttpHeaderNames#UPGRADE} header (if provided
* in the request).
*
* @param ctx the context for this handler.
* @param request the HTTP request.
* @return {@code true} if the upgrade occurred, otherwise {@code false}.
*/
private boolean upgrade(final ChannelHandlerContext ctx, final FullHttpRequest request) {
// Select the best protocol based on those requested in the UPGRADE header.
final List<CharSequence> requestedProtocols = splitHeader(request.headers().get(HttpHeaderNames.UPGRADE));
final int numRequestedProtocols = requestedProtocols.size();
UpgradeCodec upgradeCodec = null;
CharSequence upgradeProtocol = null;
for (int i = 0; i < numRequestedProtocols; i ++) {
final CharSequence p = requestedProtocols.get(i);
final UpgradeCodec c = upgradeCodecFactory.newUpgradeCodec(p);
if (c != null) {
upgradeProtocol = p;
upgradeCodec = c;
break;
}
}
if (upgradeCodec == null) {
// None of the requested protocols are supported, don't upgrade.
return false;
}
// Make sure the CONNECTION header is present.
CharSequence connectionHeader = request.headers().get(HttpHeaderNames.CONNECTION);
if (connectionHeader == null) {
return false;
}
// Make sure the CONNECTION header contains UPGRADE as well as all protocol-specific headers.
Collection<CharSequence> requiredHeaders = upgradeCodec.requiredUpgradeHeaders();
List<CharSequence> values = splitHeader(connectionHeader);
if (!containsContentEqualsIgnoreCase(values, HttpHeaderNames.UPGRADE) ||
!containsAllContentEqualsIgnoreCase(values, requiredHeaders)) {
return false;
}
// Ensure that all required protocol-specific headers are found in the request.
for (CharSequence requiredHeader : requiredHeaders) {
if (!request.headers().contains(requiredHeader)) {
return false;
}
}
// Prepare and send the upgrade response. Wait for this write to complete before upgrading,
// since we need the old codec in-place to properly encode the response.
final FullHttpResponse upgradeResponse = createUpgradeResponse(upgradeProtocol);
if (!upgradeCodec.prepareUpgradeResponse(ctx, request, upgradeResponse.headers())) {
return false;
}
// Create the user event to be fired once the upgrade completes.
final UpgradeEvent event = new UpgradeEvent(upgradeProtocol, request);
final UpgradeCodec finalUpgradeCodec = upgradeCodec;
ctx.writeAndFlush(upgradeResponse).addListener(new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
try {
if (future.isSuccess()) {
// Perform the upgrade to the new protocol.
sourceCodec.upgradeFrom(ctx);
finalUpgradeCodec.upgradeTo(ctx, request);
// Notify that the upgrade has occurred. Retain the event to offset
// the release() in the finally block.
ctx.fireUserEventTriggered(event.retain());
// Remove this handler from the pipeline.
ctx.pipeline().remove(HttpServerUpgradeHandler.this);
} else {
future.channel().close();
}
} finally {
// Release the event if the upgrade event wasn't fired.
event.release();
}
}
});
return true;
}
/**
* Creates the 101 Switching Protocols response message.
*/
private static FullHttpResponse createUpgradeResponse(CharSequence upgradeProtocol) {
DefaultFullHttpResponse res = new DefaultFullHttpResponse(HTTP_1_1, SWITCHING_PROTOCOLS,
Unpooled.EMPTY_BUFFER, false);
res.headers().add(HttpHeaderNames.CONNECTION, HttpHeaderValues.UPGRADE);
res.headers().add(HttpHeaderNames.UPGRADE, upgradeProtocol);
res.headers().add(HttpHeaderNames.CONTENT_LENGTH, HttpHeaderValues.ZERO);
return res;
}
/**
* Splits a comma-separated header value. The returned set is case-insensitive and contains each
* part with whitespace removed.
*/
private static List<CharSequence> splitHeader(CharSequence header) {
final StringBuilder builder = new StringBuilder(header.length());
final List<CharSequence> protocols = new ArrayList<CharSequence>(4);
for (int i = 0; i < header.length(); ++i) {
char c = header.charAt(i);
if (Character.isWhitespace(c)) {
// Don't include any whitespace.
continue;
}
if (c == ',') {
// Add the string and reset the builder for the next protocol.
protocols.add(builder.toString());
builder.setLength(0);
} else {
builder.append(c);
}
}
// Add the last protocol
if (builder.length() > 0) {
protocols.add(builder.toString());
}
return protocols;
}
}