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1   /*
2    * Copyright 2016 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a 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
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty5.handler.codec.http2;
17  
18  import io.netty5.handler.codec.Headers;
19  import io.netty5.util.AsciiString;
20  import io.netty5.util.HashingStrategy;
21  
22  import java.util.ArrayList;
23  import java.util.Collections;
24  import java.util.Iterator;
25  import java.util.LinkedHashSet;
26  import java.util.List;
27  import java.util.Map;
28  import java.util.NoSuchElementException;
29  import java.util.Set;
30  
31  import static io.netty5.handler.codec.CharSequenceValueConverter.INSTANCE;
32  import static io.netty5.handler.codec.http2.DefaultHttp2Headers.HTTP2_NAME_VALIDATOR;
33  import static io.netty5.util.AsciiString.CASE_INSENSITIVE_HASHER;
34  import static io.netty5.util.AsciiString.CASE_SENSITIVE_HASHER;
35  import static io.netty5.util.internal.EmptyArrays.EMPTY_ASCII_STRINGS;
36  import static io.netty5.util.internal.ObjectUtil.checkNotNullArrayParam;
37  
38  /**
39   * A variant of {@link Http2Headers} which only supports read-only methods.
40   * <p>
41   * Any array passed to this class may be used directly in the underlying data structures of this class. If these
42   * arrays may be modified it is the caller's responsibility to supply this class with a copy of the array.
43   * <p>
44   * This may be a good alternative to {@link DefaultHttp2Headers} if your have a fixed set of headers which will not
45   * change.
46   */
47  public final class ReadOnlyHttp2Headers implements Http2Headers {
48      private static final byte PSEUDO_HEADER_TOKEN = (byte) ':';
49      private final AsciiString[] pseudoHeaders;
50      private final AsciiString[] otherHeaders;
51  
52      /**
53       * Used to create read only object designed to represent trailers.
54       * <p>
55       * If this is used for a purpose other than trailers you may violate the header serialization ordering defined by
56       * <a href="https://tools.ietf.org/html/rfc7540#section-8.1.2.1">RFC 7540, 8.1.2.1</a>.
57       * @param validateHeaders {@code true} will run validation on each header name/value pair to ensure protocol
58       *                        compliance.
59       * @param otherHeaders An array of key:value pairs. Must not contain any
60       *                     <a href="https://tools.ietf.org/html/rfc7540#section-8.1.2.1">pseudo headers</a>
61       *                     or {@code null} names/values.
62       *                     A copy will <strong>NOT</strong> be made of this array. If the contents of this array
63       *                     may be modified externally you are responsible for passing in a copy.
64       * @return A read only representation of the headers.
65       */
66      public static ReadOnlyHttp2Headers trailers(boolean validateHeaders, AsciiString... otherHeaders) {
67          return new ReadOnlyHttp2Headers(validateHeaders, EMPTY_ASCII_STRINGS, otherHeaders);
68      }
69  
70      /**
71       * Create a new read only representation of headers used by clients.
72       * @param validateHeaders {@code true} will run validation on each header name/value pair to ensure protocol
73       *                        compliance.
74       * @param method The value for {@link PseudoHeaderName#METHOD}.
75       * @param path The value for {@link PseudoHeaderName#PATH}.
76       * @param scheme The value for {@link PseudoHeaderName#SCHEME}.
77       * @param authority The value for {@link PseudoHeaderName#AUTHORITY}.
78       * @param otherHeaders An array of key:value pairs. Must not contain any
79       *                     <a href="https://tools.ietf.org/html/rfc7540#section-8.1.2.1">pseudo headers</a>
80       *                     or {@code null} names/values.
81       *                     A copy will <strong>NOT</strong> be made of this array. If the contents of this array
82       *                     may be modified externally you are responsible for passing in a copy.
83       * @return a new read only representation of headers used by clients.
84       */
85      public static ReadOnlyHttp2Headers clientHeaders(boolean validateHeaders,
86                                                       AsciiString method, AsciiString path,
87                                                       AsciiString scheme, AsciiString authority,
88                                                       AsciiString... otherHeaders) {
89          return new ReadOnlyHttp2Headers(validateHeaders,
90                  new AsciiString[] {
91                    PseudoHeaderName.METHOD.value(), method, PseudoHeaderName.PATH.value(), path,
92                    PseudoHeaderName.SCHEME.value(), scheme, PseudoHeaderName.AUTHORITY.value(), authority
93                  },
94                  otherHeaders);
95      }
96  
97      /**
98       * Create a new read only representation of headers used by servers.
99       * @param validateHeaders {@code true} will run validation on each header name/value pair to ensure protocol
100      *                        compliance.
101      * @param status The value for {@link PseudoHeaderName#STATUS}.
102      * @param otherHeaders An array of key:value pairs. Must not contain any
103      *                     <a href="https://tools.ietf.org/html/rfc7540#section-8.1.2.1">pseudo headers</a>
104      *                     or {@code null} names/values.
105      *                     A copy will <strong>NOT</strong> be made of this array. If the contents of this array
106      *                     may be modified externally you are responsible for passing in a copy.
107      * @return a new read only representation of headers used by servers.
108      */
109     public static ReadOnlyHttp2Headers serverHeaders(boolean validateHeaders,
110                                                      AsciiString status,
111                                                      AsciiString... otherHeaders) {
112         return new ReadOnlyHttp2Headers(validateHeaders,
113                                         new AsciiString[] { PseudoHeaderName.STATUS.value(), status },
114                                         otherHeaders);
115     }
116 
117     private ReadOnlyHttp2Headers(boolean validateHeaders, AsciiString[] pseudoHeaders, AsciiString... otherHeaders) {
118         assert (pseudoHeaders.length & 1) == 0; // pseudoHeaders are only set internally so assert should be enough.
119         if ((otherHeaders.length & 1) != 0) {
120             throw newInvalidArraySizeException();
121         }
122         if (validateHeaders) {
123             validateHeaders(pseudoHeaders, otherHeaders);
124         }
125         this.pseudoHeaders = pseudoHeaders;
126         this.otherHeaders = otherHeaders;
127     }
128 
129     private static IllegalArgumentException newInvalidArraySizeException() {
130         return new IllegalArgumentException("pseudoHeaders and otherHeaders must be arrays of [name, value] pairs");
131     }
132 
133     private static void validateHeaders(AsciiString[] pseudoHeaders, AsciiString... otherHeaders) {
134         // We are only validating values... so start at 1 and go until the end.
135         for (int i = 1; i < pseudoHeaders.length; i += 2) {
136             // pseudoHeaders names are only set internally, so they are assumed to be valid.
137             checkNotNullArrayParam(pseudoHeaders[i], i, "pseudoHeaders");
138         }
139 
140         boolean seenNonPseudoHeader = false;
141         final int otherHeadersEnd = otherHeaders.length - 1;
142         for (int i = 0; i < otherHeadersEnd; i += 2) {
143             AsciiString name = otherHeaders[i];
144             HTTP2_NAME_VALIDATOR.validateName(name);
145             if (!seenNonPseudoHeader && !name.isEmpty() && name.byteAt(0) != PSEUDO_HEADER_TOKEN) {
146                 seenNonPseudoHeader = true;
147             } else if (seenNonPseudoHeader && !name.isEmpty() && name.byteAt(0) == PSEUDO_HEADER_TOKEN) {
148                 throw new IllegalArgumentException(
149                      "otherHeaders name at index " + i + " is a pseudo header that appears after non-pseudo headers.");
150             }
151             checkNotNullArrayParam(otherHeaders[i + 1], i + 1, "otherHeaders");
152         }
153     }
154 
155     private AsciiString get0(CharSequence name) {
156         final int nameHash = AsciiString.hashCode(name);
157 
158         final int pseudoHeadersEnd = pseudoHeaders.length - 1;
159         for (int i = 0; i < pseudoHeadersEnd; i += 2) {
160             AsciiString roName = pseudoHeaders[i];
161             if (roName.hashCode() == nameHash && roName.contentEqualsIgnoreCase(name)) {
162                 return pseudoHeaders[i + 1];
163             }
164         }
165 
166         final int otherHeadersEnd = otherHeaders.length - 1;
167         for (int i = 0; i < otherHeadersEnd; i += 2) {
168             AsciiString roName = otherHeaders[i];
169             if (roName.hashCode() == nameHash && roName.contentEqualsIgnoreCase(name)) {
170                 return otherHeaders[i + 1];
171             }
172         }
173         return null;
174     }
175 
176     @Override
177     public CharSequence get(CharSequence name) {
178         return get0(name);
179     }
180 
181     @Override
182     public CharSequence get(CharSequence name, CharSequence defaultValue) {
183         CharSequence value = get(name);
184         return value != null ? value : defaultValue;
185     }
186 
187     @Override
188     public CharSequence getAndRemove(CharSequence name) {
189         throw new UnsupportedOperationException("read only");
190     }
191 
192     @Override
193     public CharSequence getAndRemove(CharSequence name, CharSequence defaultValue) {
194         throw new UnsupportedOperationException("read only");
195     }
196 
197     @Override
198     public List<CharSequence> getAll(CharSequence name) {
199         final int nameHash = AsciiString.hashCode(name);
200         List<CharSequence> values = new ArrayList<>();
201 
202         final int pseudoHeadersEnd = pseudoHeaders.length - 1;
203         for (int i = 0; i < pseudoHeadersEnd; i += 2) {
204             AsciiString roName = pseudoHeaders[i];
205             if (roName.hashCode() == nameHash && roName.contentEqualsIgnoreCase(name)) {
206                 values.add(pseudoHeaders[i + 1]);
207             }
208         }
209 
210         final int otherHeadersEnd = otherHeaders.length - 1;
211         for (int i = 0; i < otherHeadersEnd; i += 2) {
212             AsciiString roName = otherHeaders[i];
213             if (roName.hashCode() == nameHash && roName.contentEqualsIgnoreCase(name)) {
214                 values.add(otherHeaders[i + 1]);
215             }
216         }
217 
218         return values;
219     }
220 
221     @Override
222     public List<CharSequence> getAllAndRemove(CharSequence name) {
223         throw new UnsupportedOperationException("read only");
224     }
225 
226     @Override
227     public Boolean getBoolean(CharSequence name) {
228         AsciiString value = get0(name);
229         return value != null ? INSTANCE.convertToBoolean(value) : null;
230     }
231 
232     @Override
233     public boolean getBoolean(CharSequence name, boolean defaultValue) {
234         Boolean value = getBoolean(name);
235         return value != null ? value : defaultValue;
236     }
237 
238     @Override
239     public Byte getByte(CharSequence name) {
240         AsciiString value = get0(name);
241         return value != null ? INSTANCE.convertToByte(value) : null;
242     }
243 
244     @Override
245     public byte getByte(CharSequence name, byte defaultValue) {
246         Byte value = getByte(name);
247         return value != null ? value : defaultValue;
248     }
249 
250     @Override
251     public Character getChar(CharSequence name) {
252         AsciiString value = get0(name);
253         return value != null ? INSTANCE.convertToChar(value) : null;
254     }
255 
256     @Override
257     public char getChar(CharSequence name, char defaultValue) {
258         Character value = getChar(name);
259         return value != null ? value : defaultValue;
260     }
261 
262     @Override
263     public Short getShort(CharSequence name) {
264         AsciiString value = get0(name);
265         return value != null ? INSTANCE.convertToShort(value) : null;
266     }
267 
268     @Override
269     public short getShort(CharSequence name, short defaultValue) {
270         Short value = getShort(name);
271         return value != null ? value : defaultValue;
272     }
273 
274     @Override
275     public Integer getInt(CharSequence name) {
276         AsciiString value = get0(name);
277         return value != null ? INSTANCE.convertToInt(value) : null;
278     }
279 
280     @Override
281     public int getInt(CharSequence name, int defaultValue) {
282         Integer value = getInt(name);
283         return value != null ? value : defaultValue;
284     }
285 
286     @Override
287     public Long getLong(CharSequence name) {
288         AsciiString value = get0(name);
289         return value != null ? INSTANCE.convertToLong(value) : null;
290     }
291 
292     @Override
293     public long getLong(CharSequence name, long defaultValue) {
294         Long value = getLong(name);
295         return value != null ? value : defaultValue;
296     }
297 
298     @Override
299     public Float getFloat(CharSequence name) {
300         AsciiString value = get0(name);
301         return value != null ? INSTANCE.convertToFloat(value) : null;
302     }
303 
304     @Override
305     public float getFloat(CharSequence name, float defaultValue) {
306         Float value = getFloat(name);
307         return value != null ? value : defaultValue;
308     }
309 
310     @Override
311     public Double getDouble(CharSequence name) {
312         AsciiString value = get0(name);
313         return value != null ? INSTANCE.convertToDouble(value) : null;
314     }
315 
316     @Override
317     public double getDouble(CharSequence name, double defaultValue) {
318         Double value = getDouble(name);
319         return value != null ? value : defaultValue;
320     }
321 
322     @Override
323     public Long getTimeMillis(CharSequence name) {
324         AsciiString value = get0(name);
325         if (value != null) {
326             try {
327                 return INSTANCE.convertToTimeMillis(value);
328             } catch (RuntimeException e) {
329                 return null;
330             }
331         }
332         return null;
333     }
334 
335     @Override
336     public long getTimeMillis(CharSequence name, long defaultValue) {
337         Long value = getTimeMillis(name);
338         return value != null ? value : defaultValue;
339     }
340 
341     @Override
342     public Boolean getBooleanAndRemove(CharSequence name) {
343         throw new UnsupportedOperationException("read only");
344     }
345 
346     @Override
347     public boolean getBooleanAndRemove(CharSequence name, boolean defaultValue) {
348         throw new UnsupportedOperationException("read only");
349     }
350 
351     @Override
352     public Byte getByteAndRemove(CharSequence name) {
353         throw new UnsupportedOperationException("read only");
354     }
355 
356     @Override
357     public byte getByteAndRemove(CharSequence name, byte defaultValue) {
358         throw new UnsupportedOperationException("read only");
359     }
360 
361     @Override
362     public Character getCharAndRemove(CharSequence name) {
363         throw new UnsupportedOperationException("read only");
364     }
365 
366     @Override
367     public char getCharAndRemove(CharSequence name, char defaultValue) {
368         throw new UnsupportedOperationException("read only");
369     }
370 
371     @Override
372     public Short getShortAndRemove(CharSequence name) {
373         throw new UnsupportedOperationException("read only");
374     }
375 
376     @Override
377     public short getShortAndRemove(CharSequence name, short defaultValue) {
378         throw new UnsupportedOperationException("read only");
379     }
380 
381     @Override
382     public Integer getIntAndRemove(CharSequence name) {
383         throw new UnsupportedOperationException("read only");
384     }
385 
386     @Override
387     public int getIntAndRemove(CharSequence name, int defaultValue) {
388         throw new UnsupportedOperationException("read only");
389     }
390 
391     @Override
392     public Long getLongAndRemove(CharSequence name) {
393         throw new UnsupportedOperationException("read only");
394     }
395 
396     @Override
397     public long getLongAndRemove(CharSequence name, long defaultValue) {
398         throw new UnsupportedOperationException("read only");
399     }
400 
401     @Override
402     public Float getFloatAndRemove(CharSequence name) {
403         throw new UnsupportedOperationException("read only");
404     }
405 
406     @Override
407     public float getFloatAndRemove(CharSequence name, float defaultValue) {
408         throw new UnsupportedOperationException("read only");
409     }
410 
411     @Override
412     public Double getDoubleAndRemove(CharSequence name) {
413         throw new UnsupportedOperationException("read only");
414     }
415 
416     @Override
417     public double getDoubleAndRemove(CharSequence name, double defaultValue) {
418         throw new UnsupportedOperationException("read only");
419     }
420 
421     @Override
422     public Long getTimeMillisAndRemove(CharSequence name) {
423         throw new UnsupportedOperationException("read only");
424     }
425 
426     @Override
427     public long getTimeMillisAndRemove(CharSequence name, long defaultValue) {
428         throw new UnsupportedOperationException("read only");
429     }
430 
431     @Override
432     public boolean contains(CharSequence name) {
433         return get(name) != null;
434     }
435 
436     @Override
437     public boolean contains(CharSequence name, CharSequence value) {
438         return contains(name, value, false);
439     }
440 
441     @Override
442     public boolean containsObject(CharSequence name, Object value) {
443         if (value instanceof CharSequence) {
444             return contains(name, (CharSequence) value);
445         }
446         return contains(name, value.toString());
447     }
448 
449     @Override
450     public boolean containsBoolean(CharSequence name, boolean value) {
451         return contains(name, String.valueOf(value));
452     }
453 
454     @Override
455     public boolean containsByte(CharSequence name, byte value) {
456         return contains(name, String.valueOf(value));
457     }
458 
459     @Override
460     public boolean containsChar(CharSequence name, char value) {
461         return contains(name, String.valueOf(value));
462     }
463 
464     @Override
465     public boolean containsShort(CharSequence name, short value) {
466         return contains(name, String.valueOf(value));
467     }
468 
469     @Override
470     public boolean containsInt(CharSequence name, int value) {
471         return contains(name, String.valueOf(value));
472     }
473 
474     @Override
475     public boolean containsLong(CharSequence name, long value) {
476         return contains(name, String.valueOf(value));
477     }
478 
479     @Override
480     public boolean containsFloat(CharSequence name, float value) {
481         return false;
482     }
483 
484     @Override
485     public boolean containsDouble(CharSequence name, double value) {
486         return contains(name, String.valueOf(value));
487     }
488 
489     @Override
490     public boolean containsTimeMillis(CharSequence name, long value) {
491         return contains(name, String.valueOf(value));
492     }
493 
494     @Override
495     public int size() {
496         return pseudoHeaders.length + otherHeaders.length >>> 1;
497     }
498 
499     @Override
500     public boolean isEmpty() {
501         return pseudoHeaders.length == 0 && otherHeaders.length == 0;
502     }
503 
504     @Override
505     public Set<CharSequence> names() {
506         if (isEmpty()) {
507             return Collections.emptySet();
508         }
509         Set<CharSequence> names = new LinkedHashSet<>(size());
510         final int pseudoHeadersEnd = pseudoHeaders.length - 1;
511         for (int i = 0; i < pseudoHeadersEnd; i += 2) {
512             names.add(pseudoHeaders[i]);
513         }
514 
515         final int otherHeadersEnd = otherHeaders.length - 1;
516         for (int i = 0; i < otherHeadersEnd; i += 2) {
517             names.add(otherHeaders[i]);
518         }
519         return names;
520     }
521 
522     @Override
523     public Http2Headers add(CharSequence name, CharSequence value) {
524         throw new UnsupportedOperationException("read only");
525     }
526 
527     @Override
528     public Http2Headers add(CharSequence name, Iterable<? extends CharSequence> values) {
529         throw new UnsupportedOperationException("read only");
530     }
531 
532     @Override
533     public Http2Headers add(CharSequence name, CharSequence... values) {
534         throw new UnsupportedOperationException("read only");
535     }
536 
537     @Override
538     public Http2Headers addObject(CharSequence name, Object value) {
539         throw new UnsupportedOperationException("read only");
540     }
541 
542     @Override
543     public Http2Headers addObject(CharSequence name, Iterable<?> values) {
544         throw new UnsupportedOperationException("read only");
545     }
546 
547     @Override
548     public Http2Headers addObject(CharSequence name, Object... values) {
549         throw new UnsupportedOperationException("read only");
550     }
551 
552     @Override
553     public Http2Headers addBoolean(CharSequence name, boolean value) {
554         throw new UnsupportedOperationException("read only");
555     }
556 
557     @Override
558     public Http2Headers addByte(CharSequence name, byte value) {
559         throw new UnsupportedOperationException("read only");
560     }
561 
562     @Override
563     public Http2Headers addChar(CharSequence name, char value) {
564         throw new UnsupportedOperationException("read only");
565     }
566 
567     @Override
568     public Http2Headers addShort(CharSequence name, short value) {
569         throw new UnsupportedOperationException("read only");
570     }
571 
572     @Override
573     public Http2Headers addInt(CharSequence name, int value) {
574         throw new UnsupportedOperationException("read only");
575     }
576 
577     @Override
578     public Http2Headers addLong(CharSequence name, long value) {
579         throw new UnsupportedOperationException("read only");
580     }
581 
582     @Override
583     public Http2Headers addFloat(CharSequence name, float value) {
584         throw new UnsupportedOperationException("read only");
585     }
586 
587     @Override
588     public Http2Headers addDouble(CharSequence name, double value) {
589         throw new UnsupportedOperationException("read only");
590     }
591 
592     @Override
593     public Http2Headers addTimeMillis(CharSequence name, long value) {
594         throw new UnsupportedOperationException("read only");
595     }
596 
597     @Override
598     public Http2Headers add(Headers<? extends CharSequence, ? extends CharSequence, ?> headers) {
599         throw new UnsupportedOperationException("read only");
600     }
601 
602     @Override
603     public Http2Headers set(CharSequence name, CharSequence value) {
604         throw new UnsupportedOperationException("read only");
605     }
606 
607     @Override
608     public Http2Headers set(CharSequence name, Iterable<? extends CharSequence> values) {
609         throw new UnsupportedOperationException("read only");
610     }
611 
612     @Override
613     public Http2Headers set(CharSequence name, CharSequence... values) {
614         throw new UnsupportedOperationException("read only");
615     }
616 
617     @Override
618     public Http2Headers setObject(CharSequence name, Object value) {
619         throw new UnsupportedOperationException("read only");
620     }
621 
622     @Override
623     public Http2Headers setObject(CharSequence name, Iterable<?> values) {
624         throw new UnsupportedOperationException("read only");
625     }
626 
627     @Override
628     public Http2Headers setObject(CharSequence name, Object... values) {
629         throw new UnsupportedOperationException("read only");
630     }
631 
632     @Override
633     public Http2Headers setBoolean(CharSequence name, boolean value) {
634         throw new UnsupportedOperationException("read only");
635     }
636 
637     @Override
638     public Http2Headers setByte(CharSequence name, byte value) {
639         throw new UnsupportedOperationException("read only");
640     }
641 
642     @Override
643     public Http2Headers setChar(CharSequence name, char value) {
644         throw new UnsupportedOperationException("read only");
645     }
646 
647     @Override
648     public Http2Headers setShort(CharSequence name, short value) {
649         throw new UnsupportedOperationException("read only");
650     }
651 
652     @Override
653     public Http2Headers setInt(CharSequence name, int value) {
654         throw new UnsupportedOperationException("read only");
655     }
656 
657     @Override
658     public Http2Headers setLong(CharSequence name, long value) {
659         throw new UnsupportedOperationException("read only");
660     }
661 
662     @Override
663     public Http2Headers setFloat(CharSequence name, float value) {
664         throw new UnsupportedOperationException("read only");
665     }
666 
667     @Override
668     public Http2Headers setDouble(CharSequence name, double value) {
669         throw new UnsupportedOperationException("read only");
670     }
671 
672     @Override
673     public Http2Headers setTimeMillis(CharSequence name, long value) {
674         throw new UnsupportedOperationException("read only");
675     }
676 
677     @Override
678     public Http2Headers set(Headers<? extends CharSequence, ? extends CharSequence, ?> headers) {
679         throw new UnsupportedOperationException("read only");
680     }
681 
682     @Override
683     public Http2Headers setAll(Headers<? extends CharSequence, ? extends CharSequence, ?> headers) {
684         throw new UnsupportedOperationException("read only");
685     }
686 
687     @Override
688     public boolean remove(CharSequence name) {
689         throw new UnsupportedOperationException("read only");
690     }
691 
692     @Override
693     public Http2Headers clear() {
694         throw new UnsupportedOperationException("read only");
695     }
696 
697     @Override
698     public Iterator<Map.Entry<CharSequence, CharSequence>> iterator() {
699         return new ReadOnlyIterator();
700     }
701 
702     @Override
703     public Iterator<CharSequence> valueIterator(CharSequence name) {
704         return new ReadOnlyValueIterator(name);
705     }
706 
707     @Override
708     public Http2Headers method(CharSequence value) {
709         throw new UnsupportedOperationException("read only");
710     }
711 
712     @Override
713     public Http2Headers scheme(CharSequence value) {
714         throw new UnsupportedOperationException("read only");
715     }
716 
717     @Override
718     public Http2Headers authority(CharSequence value) {
719         throw new UnsupportedOperationException("read only");
720     }
721 
722     @Override
723     public Http2Headers path(CharSequence value) {
724         throw new UnsupportedOperationException("read only");
725     }
726 
727     @Override
728     public Http2Headers status(CharSequence value) {
729         throw new UnsupportedOperationException("read only");
730     }
731 
732     @Override
733     public CharSequence method() {
734         return get(PseudoHeaderName.METHOD.value());
735     }
736 
737     @Override
738     public CharSequence scheme() {
739         return get(PseudoHeaderName.SCHEME.value());
740     }
741 
742     @Override
743     public CharSequence authority() {
744         return get(PseudoHeaderName.AUTHORITY.value());
745     }
746 
747     @Override
748     public CharSequence path() {
749         return get(PseudoHeaderName.PATH.value());
750     }
751 
752     @Override
753     public CharSequence status() {
754         return get(PseudoHeaderName.STATUS.value());
755     }
756 
757     @Override
758     public boolean contains(CharSequence name, CharSequence value, boolean caseInsensitive) {
759         final int nameHash = AsciiString.hashCode(name);
760         final HashingStrategy<CharSequence> strategy =
761                 caseInsensitive ? CASE_INSENSITIVE_HASHER : CASE_SENSITIVE_HASHER;
762         final int valueHash = strategy.hashCode(value);
763 
764         return contains(name, nameHash, value, valueHash, strategy, otherHeaders)
765                 || contains(name, nameHash, value, valueHash, strategy, pseudoHeaders);
766     }
767 
768     private static boolean contains(CharSequence name, int nameHash, CharSequence value, int valueHash,
769                                     HashingStrategy<CharSequence> hashingStrategy, AsciiString[] headers) {
770         final int headersEnd = headers.length - 1;
771         for (int i = 0; i < headersEnd; i += 2) {
772             AsciiString roName = headers[i];
773             AsciiString roValue = headers[i + 1];
774             if (roName.hashCode() == nameHash && roValue.hashCode() == valueHash &&
775                 roName.contentEqualsIgnoreCase(name) && hashingStrategy.equals(roValue, value)) {
776                 return true;
777             }
778         }
779         return false;
780     }
781 
782     @Override
783     public String toString() {
784         StringBuilder builder = new StringBuilder(getClass().getSimpleName()).append('[');
785         String separator = "";
786         for (Map.Entry<CharSequence, CharSequence> entry : this) {
787             builder.append(separator);
788             builder.append(entry.getKey()).append(": ").append(entry.getValue());
789             separator = ", ";
790         }
791         return builder.append(']').toString();
792     }
793 
794     private final class ReadOnlyValueIterator implements Iterator<CharSequence> {
795         private int i;
796         private final int nameHash;
797         private final CharSequence name;
798         private AsciiString[] current = pseudoHeaders.length != 0 ? pseudoHeaders : otherHeaders;
799         private AsciiString next;
800 
801         ReadOnlyValueIterator(CharSequence name) {
802             nameHash = AsciiString.hashCode(name);
803             this.name = name;
804             calculateNext();
805         }
806 
807         @Override
808         public boolean hasNext() {
809             return next != null;
810         }
811 
812         @Override
813         public CharSequence next() {
814             if (!hasNext()) {
815                 throw new NoSuchElementException();
816             }
817             CharSequence current = next;
818             calculateNext();
819             return current;
820         }
821 
822         @Override
823         public void remove() {
824             throw new UnsupportedOperationException("read only");
825         }
826 
827         private void calculateNext() {
828             for (; i < current.length; i += 2) {
829                 AsciiString roName = current[i];
830                 if (roName.hashCode() == nameHash && roName.contentEqualsIgnoreCase(name)) {
831                     if (i + 1 < current.length) {
832                         next = current[i + 1];
833                         i += 2;
834                     }
835                     return;
836                 }
837             }
838             if (current == pseudoHeaders) {
839                 i = 0;
840                 current = otherHeaders;
841                 calculateNext();
842             } else {
843                 next = null;
844             }
845         }
846     }
847 
848     private final class ReadOnlyIterator implements Map.Entry<CharSequence, CharSequence>,
849                                                     Iterator<Map.Entry<CharSequence, CharSequence>> {
850         private int i;
851         private AsciiString[] current = pseudoHeaders.length != 0 ? pseudoHeaders : otherHeaders;
852         private AsciiString key;
853         private AsciiString value;
854 
855         @Override
856         public boolean hasNext() {
857             return i != current.length;
858         }
859 
860         @Override
861         public Map.Entry<CharSequence, CharSequence> next() {
862             if (!hasNext()) {
863                 throw new NoSuchElementException();
864             }
865             key = current[i];
866             value = current[i + 1];
867             i += 2;
868             if (i == current.length && current == pseudoHeaders) {
869                 current = otherHeaders;
870                 i = 0;
871             }
872             return this;
873         }
874 
875         @Override
876         public CharSequence getKey() {
877             return key;
878         }
879 
880         @Override
881         public CharSequence getValue() {
882             return value;
883         }
884 
885         @Override
886         public CharSequence setValue(CharSequence value) {
887             throw new UnsupportedOperationException("read only");
888         }
889 
890         @Override
891         public void remove() {
892             throw new UnsupportedOperationException("read only");
893         }
894 
895         @Override
896         public String toString() {
897             return key.toString() + '=' + value.toString();
898         }
899     }
900 }