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Limit the number of Continuation frames per HTTP2 Headers #13969

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Limit the number of Continuation frames per HTTP2 Headers #13969

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27 changes: 26 additions & 1 deletion ...tp2/src/main/java/io/netty/handler/codec/http2/AbstractHttp2ConnectionHandlerBuilder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -112,6 +112,8 @@ public abstract class AbstractHttp2ConnectionHandlerBuilder<T extends Http2Conne
private int maxQueuedControlFrames = Http2CodecUtil.DEFAULT_MAX_QUEUED_CONTROL_FRAMES;
private int maxConsecutiveEmptyFrames = 2;
private Integer maxRstFramesPerWindow;
private int maxConsecutiveContinuationsFrames = 16;

private int secondsPerWindow = 30;

/**
Expand Down Expand Up @@ -452,6 +454,29 @@ protected B decoderEnforceMaxRstFramesPerWindow(int maxRstFramesPerWindow, int s
return self();
}

/**
* Returns the maximum number of consecutive CONTINUATION frames that are allowed before
* the connection is closed. This allows to protect against the remote peer flooding us with such frames.
*
* {@code 0} means no protection is in place.
*/
protected int decoderEnforceMaxConsecutiveContinuationsFrames() {
return maxConsecutiveEmptyFrames;
}

/**
* Sets the maximum number of consecutive CONTINUATION frames that are allowed before
* the connection is closed. This allows to protect against the remote peer flooding us with such frames.
*
* {@code 0} means no protection should be applied.
*/
protected B decoderEnforceMaxConsecutiveContinuationsFrames(int maxConsecutiveContinuationsFrames) {
enforceNonCodecConstraints("maxConsecutiveContinuationsFrames");
this.maxConsecutiveContinuationsFrames = checkPositiveOrZero(
maxConsecutiveContinuationsFrames, "maxConsecutiveContinuationsFrames");
return self();
}

/**
* Determine if settings frame should automatically be acknowledged and applied.
* @return this.
Expand Down Expand Up @@ -557,7 +582,7 @@ private T buildFromConnection(Http2Connection connection) {
Long maxHeaderListSize = initialSettings.maxHeaderListSize();
Http2FrameReader reader = new DefaultHttp2FrameReader(new DefaultHttp2HeadersDecoder(isValidateHeaders(),
maxHeaderListSize == null ? DEFAULT_HEADER_LIST_SIZE : maxHeaderListSize,
/* initialHuffmanDecodeCapacity= */ -1));
/* initialHuffmanDecodeCapacity= */ -1), maxConsecutiveContinuationsFrames);
Http2FrameWriter writer = encoderIgnoreMaxHeaderListSize == null ?
new DefaultHttp2FrameWriter(headerSensitivityDetector()) :
new DefaultHttp2FrameWriter(headerSensitivityDetector(), encoderIgnoreMaxHeaderListSize);
Expand Down
41 changes: 38 additions & 3 deletions codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.http2.Http2FrameReader.Configuration;
import io.netty.util.internal.ObjectUtil;
import io.netty.util.internal.PlatformDependent;
import io.netty.util.internal.UnstableApi;

Expand All @@ -32,6 +33,7 @@
import static io.netty.handler.codec.http2.Http2CodecUtil.headerListSizeExceeded;
import static io.netty.handler.codec.http2.Http2CodecUtil.isMaxFrameSizeValid;
import static io.netty.handler.codec.http2.Http2CodecUtil.readUnsignedInt;
import static io.netty.handler.codec.http2.Http2Error.ENHANCE_YOUR_CALM;
import static io.netty.handler.codec.http2.Http2Error.FLOW_CONTROL_ERROR;
import static io.netty.handler.codec.http2.Http2Error.FRAME_SIZE_ERROR;
import static io.netty.handler.codec.http2.Http2Error.PROTOCOL_ERROR;
Expand Down Expand Up @@ -69,7 +71,8 @@ public class DefaultHttp2FrameReader implements Http2FrameReader, Http2FrameSize
private Http2Flags flags;
private int payloadLength;
private HeadersContinuation headersContinuation;
private int maxFrameSize;
private int maxFrameSize = DEFAULT_MAX_FRAME_SIZE;
private final int maxConsecutiveContinuationsFrames;

/**
* Create a new instance.
Expand All @@ -90,8 +93,13 @@ public DefaultHttp2FrameReader(boolean validateHeaders) {
}

public DefaultHttp2FrameReader(Http2HeadersDecoder headersDecoder) {
this.headersDecoder = headersDecoder;
maxFrameSize = DEFAULT_MAX_FRAME_SIZE;
this(headersDecoder, 16);
}

public DefaultHttp2FrameReader(Http2HeadersDecoder headersDecoder, int maxConsecutiveContinuationsFrames) {
this.headersDecoder = ObjectUtil.checkNotNull(headersDecoder, "headersDecoder");
this.maxConsecutiveContinuationsFrames = ObjectUtil.checkPositiveOrZero(
maxConsecutiveContinuationsFrames, "maxConsecutiveContinuationsFrames");
}

@Override
Expand Down Expand Up @@ -392,6 +400,12 @@ private void verifyContinuationFrame() throws Http2Exception {
throw connectionError(PROTOCOL_ERROR, "Continuation stream ID does not match pending headers. "
+ "Expected %d, but received %d.", headersContinuation.getStreamId(), streamId);
}

if (headersContinuation.numFragments() >= maxConsecutiveContinuationsFrames) {
throw connectionError(ENHANCE_YOUR_CALM,
"Number of consecutive continuations frames %d exceeds maximum: %d",
headersContinuation.numFragments(), maxConsecutiveContinuationsFrames);
}
}

private void verifyUnknownFrame() throws Http2Exception {
Expand Down Expand Up @@ -652,6 +666,15 @@ private abstract class HeadersContinuation {
*/
abstract int getStreamId();

/**
* Return the number of fragments that were used so far.
*
* @return the number of fragments
*/
final int numFragments() {
return builder.numFragments();
}

/**
* Processes the next fragment for the current header block.
*
Expand Down Expand Up @@ -680,6 +703,7 @@ final void close() {
*/
protected class HeadersBlockBuilder {
private ByteBuf headerBlock;
private int numFragments;

/**
* The local header size maximum has been exceeded while accumulating bytes.
Expand All @@ -690,6 +714,15 @@ private void headerSizeExceeded() throws Http2Exception {
headerListSizeExceeded(headersDecoder.configuration().maxHeaderListSizeGoAway());
}

/**
* Return the number of fragments that was used so far.
*
* @return number of fragments.
*/
int numFragments() {
return numFragments;
}

/**
* Adds a fragment to the block.
*
Expand All @@ -701,6 +734,8 @@ private void headerSizeExceeded() throws Http2Exception {
*/
final void addFragment(ByteBuf fragment, int len, ByteBufAllocator alloc,
boolean endOfHeaders) throws Http2Exception {
numFragments++;

if (headerBlock == null) {
if (len > headersDecoder.configuration().maxHeaderListSizeGoAway()) {
headerSizeExceeded();
Expand Down
14 changes: 13 additions & 1 deletion codec-http2/src/main/java/io/netty/handler/codec/http2/Http2FrameCodecBuilder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -200,6 +200,17 @@ public Http2FrameCodecBuilder decoderEnforceMaxRstFramesPerWindow(
return super.decoderEnforceMaxRstFramesPerWindow(maxRstFramesPerWindow, secondsPerWindow);
}

@Override
public int decoderEnforceMaxConsecutiveContinuationsFrames() {
return super.decoderEnforceMaxConsecutiveContinuationsFrames();
}

@Override
public Http2FrameCodecBuilder decoderEnforceMaxConsecutiveContinuationsFrames(
int maxConsecutiveContinuationsFrames) {
return super.decoderEnforceMaxConsecutiveContinuationsFrames(maxConsecutiveContinuationsFrames);
}

/**
* Build a {@link Http2FrameCodec} object.
*/
Expand All @@ -213,7 +224,8 @@ public Http2FrameCodec build() {
Long maxHeaderListSize = initialSettings().maxHeaderListSize();
Http2FrameReader frameReader = new DefaultHttp2FrameReader(maxHeaderListSize == null ?
new DefaultHttp2HeadersDecoder(isValidateHeaders()) :
new DefaultHttp2HeadersDecoder(isValidateHeaders(), maxHeaderListSize));
new DefaultHttp2HeadersDecoder(isValidateHeaders(), maxHeaderListSize),
decoderEnforceMaxConsecutiveContinuationsFrames());

if (frameLogger() != null) {
frameWriter = new Http2OutboundFrameLogger(frameWriter, frameLogger());
Expand Down
14 changes: 13 additions & 1 deletion codec-http2/src/main/java/io/netty/handler/codec/http2/Http2MultiplexCodecBuilder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -217,6 +217,17 @@ public Http2MultiplexCodecBuilder decoderEnforceMaxRstFramesPerWindow(
return super.decoderEnforceMaxRstFramesPerWindow(maxRstFramesPerWindow, secondsPerWindow);
}

@Override
public int decoderEnforceMaxConsecutiveContinuationsFrames() {
return super.decoderEnforceMaxConsecutiveContinuationsFrames();
}

@Override
public Http2MultiplexCodecBuilder decoderEnforceMaxConsecutiveContinuationsFrames(
int maxConsecutiveContinuationsFrames) {
return super.decoderEnforceMaxConsecutiveContinuationsFrames(maxConsecutiveContinuationsFrames);
}

@Override
public Http2MultiplexCodec build() {
Http2FrameWriter frameWriter = this.frameWriter;
Expand All @@ -227,7 +238,8 @@ public Http2MultiplexCodec build() {
Long maxHeaderListSize = initialSettings().maxHeaderListSize();
Http2FrameReader frameReader = new DefaultHttp2FrameReader(maxHeaderListSize == null ?
new DefaultHttp2HeadersDecoder(isValidateHeaders()) :
new DefaultHttp2HeadersDecoder(isValidateHeaders(), maxHeaderListSize));
new DefaultHttp2HeadersDecoder(isValidateHeaders(), maxHeaderListSize),
decoderEnforceMaxConsecutiveContinuationsFrames());

if (frameLogger() != null) {
frameWriter = new Http2OutboundFrameLogger(frameWriter, frameLogger());
Expand Down
33 changes: 33 additions & 0 deletions codec-http2/src/test/java/io/netty/handler/codec/http2/DefaultHttp2FrameReaderTest.java
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Expand Up @@ -109,6 +109,39 @@ public void readHeaderFrameAndContinuationFrame() throws Http2Exception {
}
}

@Test
public void readHeaderFrameAndContinuationFrameExceedMax() throws Http2Exception {
frameReader = new DefaultHttp2FrameReader(new DefaultHttp2HeadersDecoder(true), 2);
final int streamId = 1;

final ByteBuf input = Unpooled.buffer();
try {
Http2Headers headers = new DefaultHttp2Headers()
.authority("foo")
.method("get")
.path("/")
.scheme("https");
writeHeaderFrame(input, streamId, headers,
new Http2Flags().endOfHeaders(false).endOfStream(true));
writeContinuationFrame(input, streamId, new DefaultHttp2Headers().add("foo", "bar"),
new Http2Flags().endOfHeaders(false));
writeContinuationFrame(input, streamId, new DefaultHttp2Headers().add("foo2", "bar2"),
new Http2Flags().endOfHeaders(false));
writeContinuationFrame(input, streamId, new DefaultHttp2Headers().add("foo3", "bar3"),
new Http2Flags().endOfHeaders(false));

Http2Exception ex = assertThrows(Http2Exception.class, new Executable() {
@Override
public void execute() throws Throwable {
frameReader.readFrame(ctx, input, listener);
}
});
assertEquals(Http2Error.ENHANCE_YOUR_CALM, ex.error());
} finally {
input.release();
}
}

@Test
public void readUnknownFrame() throws Http2Exception {
ByteBuf input = Unpooled.buffer();
Expand Down