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1   /*
2    * Copyright 2014 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License, version 2.0 (the
5    * "License"); you may not use this file except in compliance with the License. You may obtain a
6    * copy of the License at:
7    *
8    * https://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software distributed under the License
11   * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
12   * or implied. See the License for the specific language governing permissions and limitations under
13   * the License.
14   */
15  
16  package io.netty.handler.codec.http2;
17  
18  import io.netty.buffer.ByteBuf;
19  import io.netty.buffer.ByteBufUtil;
20  import io.netty.buffer.Unpooled;
21  import io.netty.channel.Channel;
22  import io.netty.channel.ChannelHandlerContext;
23  import io.netty.channel.ChannelPromise;
24  import io.netty.channel.DefaultChannelPromise;
25  import io.netty.handler.ssl.ApplicationProtocolNames;
26  import io.netty.util.AsciiString;
27  import io.netty.util.concurrent.EventExecutor;
28  import io.netty.util.internal.UnstableApi;
29  
30  import static io.netty.buffer.Unpooled.directBuffer;
31  import static io.netty.buffer.Unpooled.unreleasableBuffer;
32  import static io.netty.handler.codec.http2.Http2Error.PROTOCOL_ERROR;
33  import static io.netty.handler.codec.http2.Http2Exception.connectionError;
34  import static io.netty.handler.codec.http2.Http2Exception.headerListSizeError;
35  import static io.netty.util.CharsetUtil.UTF_8;
36  import static java.lang.Math.max;
37  import static java.lang.Math.min;
38  import static java.util.concurrent.TimeUnit.MILLISECONDS;
39  import static java.util.concurrent.TimeUnit.SECONDS;
40  
41  /**
42   * Constants and utility method used for encoding/decoding HTTP2 frames.
43   */
44  @UnstableApi
45  public final class Http2CodecUtil {
46      public static final int CONNECTION_STREAM_ID = 0;
47      public static final int HTTP_UPGRADE_STREAM_ID = 1;
48      public static final CharSequence HTTP_UPGRADE_SETTINGS_HEADER = AsciiString.cached("HTTP2-Settings");
49      public static final CharSequence HTTP_UPGRADE_PROTOCOL_NAME = "h2c";
50      public static final CharSequence TLS_UPGRADE_PROTOCOL_NAME = ApplicationProtocolNames.HTTP_2;
51  
52      public static final int PING_FRAME_PAYLOAD_LENGTH = 8;
53      public static final short MAX_UNSIGNED_BYTE = 0xff;
54      /**
55       * The maximum number of padding bytes. That is the 255 padding bytes appended to the end of a frame and the 1 byte
56       * pad length field.
57       */
58      public static final int MAX_PADDING = 256;
59      public static final long MAX_UNSIGNED_INT = 0xffffffffL;
60      public static final int FRAME_HEADER_LENGTH = 9;
61      public static final int SETTING_ENTRY_LENGTH = 6;
62      public static final int PRIORITY_ENTRY_LENGTH = 5;
63      public static final int INT_FIELD_LENGTH = 4;
64      public static final short MAX_WEIGHT = 256;
65      public static final short MIN_WEIGHT = 1;
66  
67      private static final ByteBuf CONNECTION_PREFACE =
68              unreleasableBuffer(directBuffer(24).writeBytes("PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n".getBytes(UTF_8)))
69                      .asReadOnly();
70  
71      private static final int MAX_PADDING_LENGTH_LENGTH = 1;
72      public static final int DATA_FRAME_HEADER_LENGTH = FRAME_HEADER_LENGTH + MAX_PADDING_LENGTH_LENGTH;
73      public static final int HEADERS_FRAME_HEADER_LENGTH =
74              FRAME_HEADER_LENGTH + MAX_PADDING_LENGTH_LENGTH + INT_FIELD_LENGTH + 1;
75      public static final int PRIORITY_FRAME_LENGTH = FRAME_HEADER_LENGTH + PRIORITY_ENTRY_LENGTH;
76      public static final int RST_STREAM_FRAME_LENGTH = FRAME_HEADER_LENGTH + INT_FIELD_LENGTH;
77      public static final int PUSH_PROMISE_FRAME_HEADER_LENGTH =
78              FRAME_HEADER_LENGTH + MAX_PADDING_LENGTH_LENGTH + INT_FIELD_LENGTH;
79      public static final int GO_AWAY_FRAME_HEADER_LENGTH = FRAME_HEADER_LENGTH + 2 * INT_FIELD_LENGTH;
80      public static final int WINDOW_UPDATE_FRAME_LENGTH = FRAME_HEADER_LENGTH + INT_FIELD_LENGTH;
81      public static final int CONTINUATION_FRAME_HEADER_LENGTH = FRAME_HEADER_LENGTH + MAX_PADDING_LENGTH_LENGTH;
82  
83      public static final char SETTINGS_HEADER_TABLE_SIZE = 1;
84      public static final char SETTINGS_ENABLE_PUSH = 2;
85      public static final char SETTINGS_MAX_CONCURRENT_STREAMS = 3;
86      public static final char SETTINGS_INITIAL_WINDOW_SIZE = 4;
87      public static final char SETTINGS_MAX_FRAME_SIZE = 5;
88      public static final char SETTINGS_MAX_HEADER_LIST_SIZE = 6;
89      public static final int NUM_STANDARD_SETTINGS = 6;
90  
91      public static final long MAX_HEADER_TABLE_SIZE = MAX_UNSIGNED_INT;
92      public static final long MAX_CONCURRENT_STREAMS = MAX_UNSIGNED_INT;
93      public static final int MAX_INITIAL_WINDOW_SIZE = Integer.MAX_VALUE;
94      public static final int MAX_FRAME_SIZE_LOWER_BOUND = 0x4000;
95      public static final int MAX_FRAME_SIZE_UPPER_BOUND = 0xffffff;
96      public static final long MAX_HEADER_LIST_SIZE = MAX_UNSIGNED_INT;
97  
98      public static final long MIN_HEADER_TABLE_SIZE = 0;
99      public static final long MIN_CONCURRENT_STREAMS = 0;
100     public static final int MIN_INITIAL_WINDOW_SIZE = 0;
101     public static final long MIN_HEADER_LIST_SIZE = 0;
102 
103     public static final int DEFAULT_WINDOW_SIZE = 65535;
104     public static final short DEFAULT_PRIORITY_WEIGHT = 16;
105     public static final int DEFAULT_HEADER_TABLE_SIZE = 4096;
106     /**
107      * <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">The initial value of this setting is unlimited</a>.
108      * However in practice we don't want to allow our peers to use unlimited memory by default. So we take advantage
109      * of the <q>For any given request, a lower limit than what is advertised MAY be enforced.</q> loophole.
110      */
111     public static final long DEFAULT_HEADER_LIST_SIZE = 8192;
112     public static final int DEFAULT_MAX_FRAME_SIZE = MAX_FRAME_SIZE_LOWER_BOUND;
113     /**
114      * The assumed minimum value for {@code SETTINGS_MAX_CONCURRENT_STREAMS} as
115      * recommended by the <a herf="https://tools.ietf.org/html/rfc7540#section-6.5.2">HTTP/2 spec</a>.
116      */
117     public static final int SMALLEST_MAX_CONCURRENT_STREAMS = 100;
118     static final int DEFAULT_MAX_RESERVED_STREAMS = SMALLEST_MAX_CONCURRENT_STREAMS;
119     static final int DEFAULT_MIN_ALLOCATION_CHUNK = 1024;
120 
121     /**
122      * Calculate the threshold in bytes which should trigger a {@code GO_AWAY} if a set of headers exceeds this amount.
123      * @param maxHeaderListSize
124      *      <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">SETTINGS_MAX_HEADER_LIST_SIZE</a> for the local
125      *      endpoint.
126      * @return the threshold in bytes which should trigger a {@code GO_AWAY} if a set of headers exceeds this amount.
127      */
128     public static long calculateMaxHeaderListSizeGoAway(long maxHeaderListSize) {
129         // This is equivalent to `maxHeaderListSize * 1.25` but we avoid floating point multiplication.
130         return maxHeaderListSize + (maxHeaderListSize >>> 2);
131     }
132 
133     public static final long DEFAULT_GRACEFUL_SHUTDOWN_TIMEOUT_MILLIS = MILLISECONDS.convert(30, SECONDS);
134 
135     public static final int DEFAULT_MAX_QUEUED_CONTROL_FRAMES = 10000;
136 
137     /**
138      * Returns {@code true} if the stream is an outbound stream.
139      *
140      * @param server    {@code true} if the endpoint is a server, {@code false} otherwise.
141      * @param streamId  the stream identifier
142      */
143     public static boolean isOutboundStream(boolean server, int streamId) {
144         boolean even = (streamId & 1) == 0;
145         return streamId > 0 && server == even;
146     }
147 
148     /**
149      * Returns true if the {@code streamId} is a valid HTTP/2 stream identifier.
150      */
151     public static boolean isStreamIdValid(int streamId) {
152         return streamId >= 0;
153     }
154 
155     static boolean isStreamIdValid(int streamId, boolean server) {
156         return isStreamIdValid(streamId) && server == ((streamId & 1) == 0);
157     }
158 
159     /**
160      * Indicates whether or not the given value for max frame size falls within the valid range.
161      */
162     public static boolean isMaxFrameSizeValid(int maxFrameSize) {
163         return maxFrameSize >= MAX_FRAME_SIZE_LOWER_BOUND && maxFrameSize <= MAX_FRAME_SIZE_UPPER_BOUND;
164     }
165 
166     /**
167      * Returns a buffer containing the {@link #CONNECTION_PREFACE}.
168      */
169     public static ByteBuf connectionPrefaceBuf() {
170         // Return a duplicate so that modifications to the reader index will not affect the original buffer.
171         return CONNECTION_PREFACE.retainedDuplicate();
172     }
173 
174     /**
175      * Iteratively looks through the causality chain for the given exception and returns the first
176      * {@link Http2Exception} or {@code null} if none.
177      */
178     public static Http2Exception getEmbeddedHttp2Exception(Throwable cause) {
179         while (cause != null) {
180             if (cause instanceof Http2Exception) {
181                 return (Http2Exception) cause;
182             }
183             cause = cause.getCause();
184         }
185         return null;
186     }
187 
188     /**
189      * Creates a buffer containing the error message from the given exception. If the cause is
190      * {@code null} returns an empty buffer.
191      */
192     public static ByteBuf toByteBuf(ChannelHandlerContext ctx, Throwable cause) {
193         if (cause == null || cause.getMessage() == null) {
194             return Unpooled.EMPTY_BUFFER;
195         }
196 
197         return ByteBufUtil.writeUtf8(ctx.alloc(), cause.getMessage());
198     }
199 
200     /**
201      * Reads a big-endian (31-bit) integer from the buffer.
202      */
203     public static int readUnsignedInt(ByteBuf buf) {
204         return buf.readInt() & 0x7fffffff;
205     }
206 
207     /**
208      * Writes an HTTP/2 frame header to the output buffer.
209      */
210     public static void writeFrameHeader(ByteBuf out, int payloadLength, byte type,
211             Http2Flags flags, int streamId) {
212         out.ensureWritable(FRAME_HEADER_LENGTH + payloadLength);
213         writeFrameHeaderInternal(out, payloadLength, type, flags, streamId);
214     }
215 
216     /**
217      * Calculate the amount of bytes that can be sent by {@code state}. The lower bound is {@code 0}.
218      */
219     public static int streamableBytes(StreamByteDistributor.StreamState state) {
220         return max(0, (int) min(state.pendingBytes(), state.windowSize()));
221     }
222 
223     /**
224      * Results in a RST_STREAM being sent for {@code streamId} due to violating
225      * <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">SETTINGS_MAX_HEADER_LIST_SIZE</a>.
226      * @param streamId The stream ID that was being processed when the exceptional condition occurred.
227      * @param maxHeaderListSize The max allowed size for a list of headers in bytes which was exceeded.
228      * @param onDecode {@code true} if the exception was encountered during decoder. {@code false} for encode.
229      * @throws Http2Exception a stream error.
230      */
231     public static void headerListSizeExceeded(int streamId, long maxHeaderListSize,
232                                               boolean onDecode) throws Http2Exception {
233         throw headerListSizeError(streamId, PROTOCOL_ERROR, onDecode, "Header size exceeded max " +
234                                   "allowed size (%d)", maxHeaderListSize);
235     }
236 
237     /**
238      * Results in a GO_AWAY being sent due to violating
239      * <a href="https://tools.ietf.org/html/rfc7540#section-6.5.2">SETTINGS_MAX_HEADER_LIST_SIZE</a> in an unrecoverable
240      * manner.
241      * @param maxHeaderListSize The max allowed size for a list of headers in bytes which was exceeded.
242      * @throws Http2Exception a connection error.
243      */
244     public static void headerListSizeExceeded(long maxHeaderListSize) throws Http2Exception {
245         throw connectionError(PROTOCOL_ERROR, "Header size exceeded max " +
246                 "allowed size (%d)", maxHeaderListSize);
247     }
248 
249     static void writeFrameHeaderInternal(ByteBuf out, int payloadLength, byte type,
250             Http2Flags flags, int streamId) {
251         out.writeMedium(payloadLength);
252         out.writeByte(type);
253         out.writeByte(flags.value());
254         out.writeInt(streamId);
255     }
256 
257     /**
258      * Provides the ability to associate the outcome of multiple {@link ChannelPromise}
259      * objects into a single {@link ChannelPromise} object.
260      */
261     static final class SimpleChannelPromiseAggregator extends DefaultChannelPromise {
262         private final ChannelPromise promise;
263         private int expectedCount;
264         private int doneCount;
265         private Throwable aggregateFailure;
266         private boolean doneAllocating;
267 
268         SimpleChannelPromiseAggregator(ChannelPromise promise, Channel c, EventExecutor e) {
269             super(c, e);
270             assert promise != null && !promise.isDone();
271             this.promise = promise;
272         }
273 
274         /**
275          * Allocate a new promise which will be used to aggregate the overall success of this promise aggregator.
276          * @return A new promise which will be aggregated.
277          * {@code null} if {@link #doneAllocatingPromises()} was previously called.
278          */
279         public ChannelPromise newPromise() {
280             assert !doneAllocating : "Done allocating. No more promises can be allocated.";
281             ++expectedCount;
282             return this;
283         }
284 
285         /**
286          * Signify that no more {@link #newPromise()} allocations will be made.
287          * The aggregation can not be successful until this method is called.
288          * @return The promise that is the aggregation of all promises allocated with {@link #newPromise()}.
289          */
290         public ChannelPromise doneAllocatingPromises() {
291             if (!doneAllocating) {
292                 doneAllocating = true;
293                 if (doneCount == expectedCount || expectedCount == 0) {
294                     return setPromise();
295                 }
296             }
297             return this;
298         }
299 
300         @Override
301         public boolean tryFailure(Throwable cause) {
302             if (allowFailure()) {
303                 ++doneCount;
304                 setAggregateFailure(cause);
305                 if (allPromisesDone()) {
306                     return tryPromise();
307                 }
308                 // TODO: We break the interface a bit here.
309                 // Multiple failure events can be processed without issue because this is an aggregation.
310                 return true;
311             }
312             return false;
313         }
314 
315         /**
316          * Fail this object if it has not already been failed.
317          * <p>
318          * This method will NOT throw an {@link IllegalStateException} if called multiple times
319          * because that may be expected.
320          */
321         @Override
322         public ChannelPromise setFailure(Throwable cause) {
323             if (allowFailure()) {
324                 ++doneCount;
325                 setAggregateFailure(cause);
326                 if (allPromisesDone()) {
327                     return setPromise();
328                 }
329             }
330             return this;
331         }
332 
333         @Override
334         public ChannelPromise setSuccess(Void result) {
335             if (awaitingPromises()) {
336                 ++doneCount;
337                 if (allPromisesDone()) {
338                     setPromise();
339                 }
340             }
341             return this;
342         }
343 
344         @Override
345         public boolean trySuccess(Void result) {
346             if (awaitingPromises()) {
347                 ++doneCount;
348                 if (allPromisesDone()) {
349                     return tryPromise();
350                 }
351                 // TODO: We break the interface a bit here.
352                 // Multiple success events can be processed without issue because this is an aggregation.
353                 return true;
354             }
355             return false;
356         }
357 
358         private boolean allowFailure() {
359             return awaitingPromises() || expectedCount == 0;
360         }
361 
362         private boolean awaitingPromises() {
363             return doneCount < expectedCount;
364         }
365 
366         private boolean allPromisesDone() {
367             return doneCount == expectedCount && doneAllocating;
368         }
369 
370         private ChannelPromise setPromise() {
371             if (aggregateFailure == null) {
372                 promise.setSuccess();
373                 return super.setSuccess(null);
374             } else {
375                 promise.setFailure(aggregateFailure);
376                 return super.setFailure(aggregateFailure);
377             }
378         }
379 
380         private boolean tryPromise() {
381             if (aggregateFailure == null) {
382                 promise.trySuccess();
383                 return super.trySuccess(null);
384             } else {
385                 promise.tryFailure(aggregateFailure);
386                 return super.tryFailure(aggregateFailure);
387             }
388         }
389 
390         private void setAggregateFailure(Throwable cause) {
391             if (aggregateFailure == null) {
392                 aggregateFailure = cause;
393             }
394         }
395     }
396 
397     public static void verifyPadding(int padding) {
398         if (padding < 0 || padding > MAX_PADDING) {
399             throw new IllegalArgumentException(String.format("Invalid padding '%d'. Padding must be between 0 and " +
400                                                              "%d (inclusive).", padding, MAX_PADDING));
401         }
402     }
403     private Http2CodecUtil() { }
404 }