summaryrefslogtreecommitdiff
path: root/netwerk/streamconv/converters/nsHTTPCompressConv.cpp
blob: 6030e1c8d6557abe2fc0e62ea88d8e40e281ca06 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsHTTPCompressConv.h"
#include "nsMemory.h"
#include "plstr.h"
#include "nsCOMPtr.h"
#include "nsError.h"
#include "nsStreamUtils.h"
#include "nsStringStream.h"
#include "nsComponentManagerUtils.h"
#include "nsThreadUtils.h"
#include "mozilla/Preferences.h"
#include "mozilla/Logging.h"
#include "mozilla/UniquePtrExtensions.h"
#include "nsIForcePendingChannel.h"
#include "nsIRequest.h"
#include <inttypes.h>

// brotli headers
#include "state.h"
#include "brotli/decode.h"

namespace mozilla {
namespace net {

extern LazyLogModule gHttpLog;
#define LOG(args) MOZ_LOG(mozilla::net::gHttpLog, mozilla::LogLevel::Debug, args)

// nsISupports implementation
NS_IMPL_ISUPPORTS(nsHTTPCompressConv,
                  nsIStreamConverter,
                  nsIStreamListener,
                  nsIRequestObserver,
                  nsICompressConvStats,
                  nsIThreadRetargetableStreamListener)

// nsFTPDirListingConv methods
nsHTTPCompressConv::nsHTTPCompressConv()
  : mMode(HTTP_COMPRESS_IDENTITY)
  , mOutBuffer(nullptr)
  , mInpBuffer(nullptr)
  , mOutBufferLen(0)
  , mInpBufferLen(0)
  , mCheckHeaderDone(false)
  , mStreamEnded(false)
  , mStreamInitialized(false)
  , mDummyStreamInitialised(false)
  , d_stream{}
  , mLen(0)
  , hMode(0)
  , mSkipCount(0)
  , mFlags(0)
  , mDecodedDataLength(0)
  , mMutex("nsHTTPCompressConv")
{
  LOG(("nsHttpCompresssConv %p ctor\n", this));
  if (NS_IsMainThread()) {
    mFailUncleanStops =
      Preferences::GetBool("network.http.enforce-framing.http", false);
  } else {
    mFailUncleanStops = false;
  }
}

nsHTTPCompressConv::~nsHTTPCompressConv() {
  LOG(("nsHttpCompresssConv %p dtor\n", this));
  if (mInpBuffer) {
    free(mInpBuffer);
  }

  if (mOutBuffer) {
    free(mOutBuffer);
  }

  // For some reason we are not getting Z_STREAM_END.  But this was also seen
  //    for mozilla bug 198133.  Need to handle this case.
  if (mStreamInitialized && !mStreamEnded) {
    inflateEnd(&d_stream);
  }
}

NS_IMETHODIMP
nsHTTPCompressConv::GetDecodedDataLength(uint64_t* aDecodedDataLength) {
  *aDecodedDataLength = mDecodedDataLength;
  return NS_OK;
}

NS_IMETHODIMP
nsHTTPCompressConv::AsyncConvertData(const char* aFromType, const char* aToType,
                                     nsIStreamListener* aListener,
                                     nsISupports* aCtxt) {
  if (!PL_strncasecmp(aFromType, HTTP_COMPRESS_TYPE, sizeof(HTTP_COMPRESS_TYPE) - 1) ||
      !PL_strncasecmp(aFromType, HTTP_X_COMPRESS_TYPE, sizeof(HTTP_X_COMPRESS_TYPE) - 1)) {
    mMode = HTTP_COMPRESS_COMPRESS;
  } else if (!PL_strncasecmp(aFromType, HTTP_GZIP_TYPE, sizeof(HTTP_GZIP_TYPE) - 1) ||
             !PL_strncasecmp(aFromType, HTTP_X_GZIP_TYPE, sizeof(HTTP_X_GZIP_TYPE) - 1)) {
    mMode = HTTP_COMPRESS_GZIP;
  } else if (!PL_strncasecmp(aFromType, HTTP_DEFLATE_TYPE, sizeof(HTTP_DEFLATE_TYPE) - 1)) {
    mMode = HTTP_COMPRESS_DEFLATE;
  } else if (!PL_strncasecmp(aFromType, HTTP_BROTLI_TYPE, sizeof(HTTP_BROTLI_TYPE) - 1)) {
    mMode = HTTP_COMPRESS_BROTLI;
  }
  LOG(("nsHttpCompresssConv %p AsyncConvertData %s %s mode %d\n", this,
       aFromType, aToType, (CompressMode)mMode));

  MutexAutoLock lock(mMutex);
  // hook ourself up with the receiving listener.
  mListener = aListener;

  return NS_OK;
}

NS_IMETHODIMP
nsHTTPCompressConv::OnStartRequest(nsIRequest* request, nsISupports* aContext) {
  LOG(("nsHttpCompresssConv %p onstart\n", this));
  nsCOMPtr<nsIStreamListener> listener;
  {
    MutexAutoLock lock(mMutex);
    listener = mListener;
  }
  return listener->OnStartRequest(request, aContext);
}

NS_IMETHODIMP
nsHTTPCompressConv::OnStopRequest(nsIRequest* request, nsISupports* aContext,
                                  nsresult aStatus) {
  nsresult status = aStatus;
  LOG(("nsHttpCompresssConv %p onstop %" PRIx32 "\n", this,
       static_cast<uint32_t>(aStatus)));

  // Framing integrity is enforced for content-encoding: gzip, but not for
  // content-encoding: deflate. Note that gzip vs deflate is NOT determined
  // by content sniffing but only via header.
  if (!mStreamEnded && NS_SUCCEEDED(status) &&
      (mFailUncleanStops && (mMode == HTTP_COMPRESS_GZIP))) {
    // This is not a clean end of gzip stream: the transfer is incomplete.
    status = NS_ERROR_NET_PARTIAL_TRANSFER;
    LOG(("nsHttpCompresssConv %p onstop partial gzip\n", this));
  }
  if (NS_SUCCEEDED(status) && mMode == HTTP_COMPRESS_BROTLI) {
    nsCOMPtr<nsIForcePendingChannel> fpChannel = do_QueryInterface(request);
    bool isPending = false;
    if (request) {
      request->IsPending(&isPending);
    }
    if (fpChannel && !isPending) {
      fpChannel->ForcePending(true);
    }
    if (mBrotli && (mBrotli->mTotalOut == 0) && !mBrotli->mBrotliStateIsStreamEnd) {
      status = NS_ERROR_INVALID_CONTENT_ENCODING;
    }
    LOG(("nsHttpCompresssConv %p onstop brotlihandler rv %" PRIx32 "\n", this,
         static_cast<uint32_t>(status)));
    if (fpChannel && !isPending) {
      fpChannel->ForcePending(false);
    }
  }

  nsCOMPtr<nsIStreamListener> listener;
  {
    MutexAutoLock lock(mMutex);
    listener = mListener;
  }
  return listener->OnStopRequest(request, aContext, status);
}

/* static */
nsresult nsHTTPCompressConv::BrotliHandler(nsIInputStream* stream,
                                           void* closure,
                                           const char* dataIn,
                                           uint32_t,
                                           uint32_t aAvail,
                                           uint32_t* countRead) {
  MOZ_ASSERT(stream);
  nsHTTPCompressConv* self = static_cast<nsHTTPCompressConv*>(closure);
  *countRead = 0;

  const size_t kOutSize = 128 * 1024;  // just a chunk size, we call in a loop
  uint8_t* outPtr;
  size_t outSize;
  size_t avail = aAvail;
  BrotliDecoderResult res;

  if (!self->mBrotli) {
    *countRead = aAvail;
    return NS_OK;
  }

  auto outBuffer = MakeUniqueFallible<uint8_t[]>(kOutSize);
  if (outBuffer == nullptr) {
    self->mBrotli->mStatus = NS_ERROR_OUT_OF_MEMORY;
    return self->mBrotli->mStatus;
  }

  do {
    outSize = kOutSize;
    outPtr = outBuffer.get();

    // brotli api is documented in brotli/dec/decode.h and brotli/dec/decode.c
    LOG(("nsHttpCompresssConv %p brotlihandler decompress %zu\n", self, avail));
    size_t totalOut = self->mBrotli->mTotalOut;
    res = ::BrotliDecoderDecompressStream(
        &self->mBrotli->mState, &avail,
        reinterpret_cast<const unsigned char**>(&dataIn), &outSize, &outPtr,
        &totalOut);
    outSize = kOutSize - outSize;
    self->mBrotli->mTotalOut = totalOut;
    self->mBrotli->mBrotliStateIsStreamEnd =
        BrotliDecoderIsFinished(&self->mBrotli->mState);
    LOG(("nsHttpCompresssConv %p brotlihandler decompress rv=%" PRIx32
         " out=%zu\n",
         self, static_cast<uint32_t>(res), outSize));

    if (res == BROTLI_DECODER_RESULT_ERROR) {
      LOG(("nsHttpCompressConv %p marking invalid encoding", self));
      self->mBrotli->mStatus = NS_ERROR_INVALID_CONTENT_ENCODING;
      return self->mBrotli->mStatus;
    }

    // in 'the current implementation' brotli must consume everything before
    // asking for more input
    if (res == BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT) {
      MOZ_ASSERT(!avail);
      if (avail) {
        LOG(("nsHttpCompressConv %p did not consume all input", self));
        self->mBrotli->mStatus = NS_ERROR_UNEXPECTED;
        return self->mBrotli->mStatus;
      }
    }
    if (outSize > 0) {
      nsresult rv = self->do_OnDataAvailable(self->mBrotli->mRequest,
                                             self->mBrotli->mContext,
                                             self->mBrotli->mSourceOffset,
                                             reinterpret_cast<const char*>(outBuffer.get()),
                                             outSize);
      LOG(("nsHttpCompressConv %p BrotliHandler ODA rv=%" PRIx32, self,
           static_cast<uint32_t>(rv)));
      if (NS_FAILED(rv)) {
        self->mBrotli->mStatus = rv;
        return self->mBrotli->mStatus;
      }
    }

    if (res == BROTLI_DECODER_RESULT_SUCCESS ||
        res == BROTLI_DECODER_RESULT_NEEDS_MORE_INPUT) {
      *countRead = aAvail;
      return NS_OK;
    }
    MOZ_ASSERT(res == BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT);
  } while (res == BROTLI_DECODER_RESULT_NEEDS_MORE_OUTPUT);

  self->mBrotli->mStatus = NS_ERROR_UNEXPECTED;
  return self->mBrotli->mStatus;
}

NS_IMETHODIMP
nsHTTPCompressConv::OnDataAvailable(nsIRequest* request,
                                    nsISupports* aContext,
                                    nsIInputStream* iStr,
                                    uint64_t aSourceOffset,
                                    uint32_t aCount) {
  nsresult rv = NS_ERROR_INVALID_CONTENT_ENCODING;
  uint32_t streamLen = aCount;
  LOG(("nsHttpCompressConv %p OnDataAvailable %d", this, aCount));

  if (streamLen == 0) {
    NS_ERROR("count of zero passed to OnDataAvailable");
    return NS_ERROR_UNEXPECTED;
  }

  if (mStreamEnded) {
    // Hmm... this may just indicate that the data stream is done and that
    // what's left is either metadata or padding of some sort.... throwing
    // it out is probably the safe thing to do.
    uint32_t n;
    return iStr->ReadSegments(NS_DiscardSegment, nullptr, streamLen, &n);
  }

  switch (mMode) {
    case HTTP_COMPRESS_GZIP:
      streamLen = check_header(iStr, streamLen, &rv);

      if (rv != NS_OK) {
        return rv;
      }

      if (streamLen == 0) {
        return NS_OK;
      }

      [[fallthrough]];

    case HTTP_COMPRESS_DEFLATE:

      if (mInpBuffer != nullptr && streamLen > mInpBufferLen) {
        unsigned char* originalInpBuffer = mInpBuffer;
        if (!(mInpBuffer = (unsigned char*)realloc(originalInpBuffer, mInpBufferLen = streamLen))) {
          free(originalInpBuffer);
        }

        if (mOutBufferLen < streamLen * 2) {
          unsigned char* originalOutBuffer = mOutBuffer;
          if (!(mOutBuffer = (unsigned char*)realloc(mOutBuffer, mOutBufferLen = streamLen * 3))) {
            free(originalOutBuffer);
          }
        }

        if (mInpBuffer == nullptr || mOutBuffer == nullptr) {
          return NS_ERROR_OUT_OF_MEMORY;
        }
      }

      if (mInpBuffer == nullptr) {
        mInpBuffer = (unsigned char*)malloc(mInpBufferLen = streamLen);
      }

      if (mOutBuffer == nullptr) {
        mOutBuffer = (unsigned char*)malloc(mOutBufferLen = streamLen * 3);
      }

      if (mInpBuffer == nullptr || mOutBuffer == nullptr) {
        return NS_ERROR_OUT_OF_MEMORY;
      }

      uint32_t unused;
      iStr->Read((char*)mInpBuffer, streamLen, &unused);

      if (mMode == HTTP_COMPRESS_DEFLATE) {
        if (!mStreamInitialized) {
          memset(&d_stream, 0, sizeof(d_stream));

          if (inflateInit(&d_stream) != Z_OK) {
            return NS_ERROR_FAILURE;
          }

          mStreamInitialized = true;
        }
        d_stream.next_in = mInpBuffer;
        d_stream.avail_in = (uInt)streamLen;

        mDummyStreamInitialised = false;
        for (;;) {
          d_stream.next_out = mOutBuffer;
          d_stream.avail_out = (uInt)mOutBufferLen;

          int code = inflate(&d_stream, Z_NO_FLUSH);
          unsigned bytesWritten = (uInt)mOutBufferLen - d_stream.avail_out;

          if (code == Z_STREAM_END) {
            if (bytesWritten) {
              rv = do_OnDataAvailable(request, aContext, aSourceOffset, (char*)mOutBuffer, bytesWritten);
              if (NS_FAILED(rv)) {
                return rv;
              }
            }

            inflateEnd(&d_stream);
            mStreamEnded = true;
            break;
          } else if (code == Z_OK) {
            if (bytesWritten) {
              rv = do_OnDataAvailable(request, aContext, aSourceOffset, (char*)mOutBuffer, bytesWritten);
              if (NS_FAILED(rv)) {
                return rv;
              }
            }
          } else if (code == Z_BUF_ERROR) {
            if (bytesWritten) {
              rv = do_OnDataAvailable(request, aContext, aSourceOffset, (char*)mOutBuffer, bytesWritten);
              if (NS_FAILED(rv)) {
                return rv;
              }
            }
            break;
          } else if (code == Z_DATA_ERROR) {
            // some servers (notably Apache with mod_deflate) don't generate
            // zlib headers insert a dummy header and try again
            static char dummy_head[2] = {
                0x8 + 0x7 * 0x10,
                (((0x8 + 0x7 * 0x10) * 0x100 + 30) / 31 * 31) & 0xFF,
            };
            inflateReset(&d_stream);
            d_stream.next_in = (Bytef*)dummy_head;
            d_stream.avail_in = sizeof(dummy_head);

            code = inflate(&d_stream, Z_NO_FLUSH);
            if (code != Z_OK) {
              return NS_ERROR_FAILURE;
            }

            // stop an endless loop caused by non-deflate data being labelled as
            // deflate
            if (mDummyStreamInitialised) {
              NS_WARNING(
                  "endless loop detected"
                  " - invalid deflate");
              return NS_ERROR_INVALID_CONTENT_ENCODING;
            }
            mDummyStreamInitialised = true;
            // reset stream pointers to our original data
            d_stream.next_in = mInpBuffer;
            d_stream.avail_in = (uInt)streamLen;
          } else {
            return NS_ERROR_INVALID_CONTENT_ENCODING;
          }
        } /* for */
      } else {
        if (!mStreamInitialized) {
          memset(&d_stream, 0, sizeof(d_stream));

          if (inflateInit2(&d_stream, -MAX_WBITS) != Z_OK) {
            return NS_ERROR_FAILURE;
          }

          mStreamInitialized = true;
        }

        d_stream.next_in = mInpBuffer;
        d_stream.avail_in = (uInt)streamLen;

        for (;;) {
          d_stream.next_out = mOutBuffer;
          d_stream.avail_out = (uInt)mOutBufferLen;

          int code = inflate(&d_stream, Z_NO_FLUSH);
          unsigned bytesWritten = (uInt)mOutBufferLen - d_stream.avail_out;

          if (code == Z_STREAM_END) {
            if (bytesWritten) {
              rv = do_OnDataAvailable(request, aContext, aSourceOffset, (char*)mOutBuffer, bytesWritten);
              if (NS_FAILED(rv)) {
                return rv;
              }
            }

            inflateEnd(&d_stream);
            mStreamEnded = true;
            break;
          } else if (code == Z_OK) {
            if (bytesWritten) {
              rv = do_OnDataAvailable(request, aContext, aSourceOffset, (char*)mOutBuffer, bytesWritten);
              if (NS_FAILED(rv)) {
                return rv;
              }
            }
          } else if (code == Z_BUF_ERROR) {
            if (bytesWritten) {
              rv = do_OnDataAvailable(request, aContext, aSourceOffset, (char*)mOutBuffer, bytesWritten);
              if (NS_FAILED(rv)) {
                return rv;
              }
            }
            break;
          } else {
            return NS_ERROR_INVALID_CONTENT_ENCODING;
          }
        } /* for */
      }   /* gzip */
      break;

    case HTTP_COMPRESS_BROTLI: {
      if (!mBrotli) {
        mBrotli = new BrotliWrapper();
      }

      mBrotli->mRequest = request;
      mBrotli->mContext = nullptr;
      mBrotli->mSourceOffset = aSourceOffset;

      uint32_t countRead;
      rv = iStr->ReadSegments(BrotliHandler, this, streamLen, &countRead);
      if (NS_SUCCEEDED(rv)) {
        rv = mBrotli->mStatus;
      }
      if (NS_FAILED(rv)) {
        return rv;
      }
    } break;

    default:
      nsCOMPtr<nsIStreamListener> listener;
      {
        MutexAutoLock lock(mMutex);
        listener = mListener;
      }
      rv = listener->OnDataAvailable(request, aContext, iStr, aSourceOffset, aCount);
      if (NS_FAILED(rv)) {
        return rv;
      }
  } /* switch */

  return NS_OK;
} /* OnDataAvailable */

// XXX/ruslan: need to implement this too

NS_IMETHODIMP
nsHTTPCompressConv::Convert(nsIInputStream* aFromStream,
                            const char* aFromType,
                            const char* aToType,
                            nsISupports* aCtxt,
                            nsIInputStream** _retval) {
  return NS_ERROR_NOT_IMPLEMENTED;
}

nsresult nsHTTPCompressConv::do_OnDataAvailable(nsIRequest* request,
                                                nsISupports* context,
                                                uint64_t offset,
                                                const char* buffer,
                                                uint32_t count) {
  if (!mStream) {
    mStream = do_CreateInstance(NS_STRINGINPUTSTREAM_CONTRACTID);
    NS_ENSURE_STATE(mStream);
  }

  mStream->ShareData(buffer, count);

  nsCOMPtr<nsIStreamListener> listener;
  {
    MutexAutoLock lock(mMutex);
    listener = mListener;
  }
  nsresult rv = listener->OnDataAvailable(request, context, mStream, offset, count);

  // Make sure the stream no longer references |buffer| in case our listener
  // is crazy enough to try to read from |mStream| after ODA.
  mStream->ShareData("", 0);
  mDecodedDataLength += count;

  return rv;
}

#define ASCII_FLAG  0x01 /* bit 0 set: file probably ascii text */
#define HEAD_CRC    0x02 /* bit 1 set: header CRC present */
#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
#define ORIG_NAME   0x08 /* bit 3 set: original file name present */
#define COMMENT     0x10 /* bit 4 set: file comment present */
#define RESERVED    0xE0 /* bits 5..7: reserved */

static unsigned gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */

uint32_t nsHTTPCompressConv::check_header(nsIInputStream* iStr,
                                          uint32_t streamLen, nsresult* rs) {
  enum {
    GZIP_INIT = 0,
    GZIP_OS,
    GZIP_EXTRA0,
    GZIP_EXTRA1,
    GZIP_EXTRA2,
    GZIP_ORIG,
    GZIP_COMMENT,
    GZIP_CRC
  };
  char c;

  *rs = NS_OK;

  if (mCheckHeaderDone) {
    return streamLen;
  }

  while (streamLen) {
    switch (hMode) {
      case GZIP_INIT:
        uint32_t unused;
        iStr->Read(&c, 1, &unused);
        streamLen--;

        if (mSkipCount == 0 && ((unsigned)c & 0377) != gz_magic[0]) {
          *rs = NS_ERROR_INVALID_CONTENT_ENCODING;
          return 0;
        }

        if (mSkipCount == 1 && ((unsigned)c & 0377) != gz_magic[1]) {
          *rs = NS_ERROR_INVALID_CONTENT_ENCODING;
          return 0;
        }

        if (mSkipCount == 2 && ((unsigned)c & 0377) != Z_DEFLATED) {
          *rs = NS_ERROR_INVALID_CONTENT_ENCODING;
          return 0;
        }

        mSkipCount++;
        if (mSkipCount == 4) {
          mFlags = (unsigned)c & 0377;
          if (mFlags & RESERVED) {
            *rs = NS_ERROR_INVALID_CONTENT_ENCODING;
            return 0;
          }
          hMode = GZIP_OS;
          mSkipCount = 0;
        }
        break;

      case GZIP_OS:
        iStr->Read(&c, 1, &unused);
        streamLen--;
        mSkipCount++;

        if (mSkipCount == 6) {
          hMode = GZIP_EXTRA0;
        }
        break;

      case GZIP_EXTRA0:
        if (mFlags & EXTRA_FIELD) {
          iStr->Read(&c, 1, &unused);
          streamLen--;
          mLen = (uInt)c & 0377;
          hMode = GZIP_EXTRA1;
        } else {
          hMode = GZIP_ORIG;
        }
        break;

      case GZIP_EXTRA1:
        iStr->Read(&c, 1, &unused);
        streamLen--;
        mLen |= ((uInt)c & 0377) << 8;
        mSkipCount = 0;
        hMode = GZIP_EXTRA2;
        break;

      case GZIP_EXTRA2:
        if (mSkipCount == mLen) {
          hMode = GZIP_ORIG;
        } else {
          iStr->Read(&c, 1, &unused);
          streamLen--;
          mSkipCount++;
        }
        break;

      case GZIP_ORIG:
        if (mFlags & ORIG_NAME) {
          iStr->Read(&c, 1, &unused);
          streamLen--;
          if (c == 0) hMode = GZIP_COMMENT;
        } else {
          hMode = GZIP_COMMENT;
        }
        break;

      case GZIP_COMMENT:
        if (mFlags & COMMENT) {
          iStr->Read(&c, 1, &unused);
          streamLen--;
          if (c == 0) {
            hMode = GZIP_CRC;
            mSkipCount = 0;
          }
        } else {
          hMode = GZIP_CRC;
          mSkipCount = 0;
        }
        break;

      case GZIP_CRC:
        if (mFlags & HEAD_CRC) {
          iStr->Read(&c, 1, &unused);
          streamLen--;
          mSkipCount++;
          if (mSkipCount == 2) {
            mCheckHeaderDone = true;
            return streamLen;
          }
        } else {
          mCheckHeaderDone = true;
          return streamLen;
        }
        break;
    }
  }
  return streamLen;
}

NS_IMETHODIMP
nsHTTPCompressConv::CheckListenerChain() {
  nsCOMPtr<nsIThreadRetargetableStreamListener> listener;
  {
    MutexAutoLock lock(mMutex);
    listener = do_QueryInterface(mListener);
  }

  if (!listener) {
    return NS_ERROR_NO_INTERFACE;
  }

  return listener->CheckListenerChain();
}

}  // namespace net
}  // namespace mozilla

nsresult NS_NewHTTPCompressConv(
    mozilla::net::nsHTTPCompressConv** aHTTPCompressConv) {
  MOZ_ASSERT(aHTTPCompressConv != nullptr, "null ptr");
  if (!aHTTPCompressConv) {
    return NS_ERROR_NULL_POINTER;
  }

  RefPtr<mozilla::net::nsHTTPCompressConv> outVal =
      new mozilla::net::nsHTTPCompressConv();
  if (!outVal) {
    return NS_ERROR_OUT_OF_MEMORY;
  }
  outVal.forget(aHTTPCompressConv);
  return NS_OK;
}