balsa_headers.h revision f8ee788a64d60abd8f2d742a5fdedde054ecd910
1// Copyright 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_TOOLS_BALSA_BALSA_HEADERS_H_
6#define NET_TOOLS_BALSA_BALSA_HEADERS_H_
7
8#include <algorithm>
9#include <iosfwd>
10#include <iterator>
11#include <string>
12#include <utility>
13#include <vector>
14
15#include "base/logging.h"
16#include "base/port.h"
17#include "base/strings/string_piece.h"
18#include "net/tools/balsa/balsa_enums.h"
19#include "net/tools/balsa/string_piece_utils.h"
20
21namespace net {
22
23// WARNING:
24// Note that -no- char* returned by any function in this
25// file is null-terminated.
26
27// This class exists to service the specific needs of BalsaHeaders.
28//
29// Functional goals:
30//   1) provide a backing-store for all of the StringPieces that BalsaHeaders
31//      returns. Every StringPiece returned from BalsaHeaders should remain
32//      valid until the BalsaHeader's object is cleared, or the header-line is
33//      erased.
34//   2) provide a backing-store for BalsaFrame, which requires contiguous memory
35//      for its fast-path parsing functions. Note that the cost of copying is
36//      less than the cost of requiring the parser to do slow-path parsing, as
37//      it would have to check for bounds every byte, instead of every 16 bytes.
38//
39// This class is optimized for the case where headers are stored in one of two
40// buffers. It doesn't make a lot of effort to densely pack memory-- in fact,
41// it -may- be somewhat memory inefficient. This possible inefficiency allows a
42// certain simplicity of implementation and speed which makes it worthwhile.
43// If, in the future, better memory density is required, it should be possible
44// to reuse the abstraction presented by this object to achieve those goals.
45//
46// In the most common use-case, this memory inefficiency should be relatively
47// small.
48//
49// Alternate implementations of BalsaBuffer may include:
50//  - vector of strings, one per header line (similar to HTTPHeaders)
51//  - densely packed strings:
52//    - keep a sorted array/map of free-space linked lists or numbers.
53//      - use the entry that most closely first your needs.
54//    - at this point, perhaps just use a vector of strings, and let
55//      the allocator do the right thing.
56//
57class BalsaBuffer {
58 public:
59  static const size_t kDefaultBlocksize = 4096;
60  // We have two friends here. These exist as friends as we
61  // want to allow access to the constructors for the test
62  // class and the Balsa* classes. We put this into the
63  // header file as we want this class to be inlined into the
64  // BalsaHeaders implementation, yet be testable.
65  friend class BalsaBufferTestSpouse;
66  friend class BalsaHeaders;
67  friend class BalsaBufferTest;
68
69  // The BufferBlock is a structure used internally by the
70  // BalsaBuffer class to store the base buffer pointers to
71  // each block, as well as the important metadata for buffer
72  // sizes and bytes free.
73  struct BufferBlock {
74   public:
75    char* buffer;
76    size_t buffer_size;
77    size_t bytes_free;
78
79    size_t bytes_used() const {
80      return buffer_size - bytes_free;
81    }
82    char* start_of_unused_bytes() const {
83      return buffer + bytes_used();
84    }
85
86    BufferBlock() : buffer(NULL), buffer_size(0), bytes_free(0) {}
87    ~BufferBlock() {}
88
89    BufferBlock(char* buf, size_t size, size_t free) :
90        buffer(buf), buffer_size(size), bytes_free(free) {}
91    // Yes we want this to be copyable (it gets stuck into vectors).
92    // For this reason, we don't use scoped ptrs, etc. here-- it
93    // is more efficient to manage this memory externally to this
94    // object.
95  };
96
97  typedef std::vector<BufferBlock> Blocks;
98
99  ~BalsaBuffer();
100
101  // Returns the total amount of memory used by the buffer blocks.
102  size_t GetTotalBufferBlockSize() const;
103
104  const char* GetPtr(Blocks::size_type block_idx) const {
105    DCHECK_LT(block_idx, blocks_.size())
106      << block_idx << ", " << blocks_.size();
107    return blocks_[block_idx].buffer;
108  }
109
110  char* GetPtr(Blocks::size_type block_idx) {
111    DCHECK_LT(block_idx, blocks_.size())
112      << block_idx << ", " << blocks_.size();
113    return blocks_[block_idx].buffer;
114  }
115
116  // This function is different from Write(), as it ensures that the data
117  // stored via subsequent calls to this function are all contiguous (and in
118  // the order in which these writes happened). This is essentially the same
119  // as a string append.
120  //
121  // You may call this function at any time between object
122  // construction/Clear(), and the calling of the
123  // NoMoreWriteToContiguousBuffer() function.
124  //
125  // You must not call this function after the NoMoreWriteToContiguousBuffer()
126  // function is called, unless a Clear() has been called since.
127  // If you do, the program will abort().
128  //
129  // This condition is placed upon this code so that calls to Write() can
130  // append to the buffer in the first block safely, and without invaliding
131  // the StringPiece which it returns.
132  //
133  // This function's main intended user is the BalsaFrame class, which,
134  // for reasons of efficiency, requires that the buffer from which it parses
135  // the headers be contiguous.
136  //
137  void WriteToContiguousBuffer(const base::StringPiece& sp);
138
139  void NoMoreWriteToContiguousBuffer() {
140    can_write_to_contiguous_buffer_ = false;
141  }
142
143  // Takes a StringPiece and writes it to "permanent" storage, then returns a
144  // StringPiece which points to that data.  If block_idx != NULL, it will be
145  // assigned the index of the block into which the data was stored.
146  // Note that the 'permanent' storage in which it stores data may be in
147  // the first block IFF the NoMoreWriteToContiguousBuffer function has
148  // been called since the last Clear/Construction.
149  base::StringPiece Write(const base::StringPiece& sp,
150                          Blocks::size_type* block_buffer_idx);
151
152  // Reserves "permanent" storage of the size indicated. Returns a pointer to
153  // the beginning of that storage, and assigns the index of the block used to
154  // block_buffer_idx. This function uses the first block IFF the
155  // NoMoreWriteToContiguousBuffer function has been called since the last
156  // Clear/Construction.
157  char* Reserve(size_t size, Blocks::size_type* block_buffer_idx);
158
159  void Clear();
160
161  void Swap(BalsaBuffer* b);
162
163  void CopyFrom(const BalsaBuffer& b);
164
165  const char* StartOfFirstBlock() const {
166    return blocks_[0].buffer;
167  }
168
169  const char* EndOfFirstBlock() const {
170    return blocks_[0].buffer + blocks_[0].bytes_used();
171  }
172
173  bool can_write_to_contiguous_buffer() const {
174    return can_write_to_contiguous_buffer_;
175  }
176  size_t blocksize() const { return blocksize_; }
177  Blocks::size_type num_blocks() const { return blocks_.size(); }
178  size_t buffer_size(size_t idx) const { return blocks_[idx].buffer_size; }
179  size_t bytes_used(size_t idx) const { return blocks_[idx].bytes_used(); }
180
181 protected:
182  BalsaBuffer();
183
184  explicit BalsaBuffer(size_t blocksize);
185
186  BufferBlock AllocBlock();
187
188  BufferBlock AllocCustomBlock(size_t blocksize);
189
190  BufferBlock CopyBlock(const BufferBlock& b);
191
192  // Cleans up the object.
193  // The block at start_idx, and all subsequent blocks
194  // will be cleared and have associated memory deleted.
195  void CleanupBlocksStartingFrom(Blocks::size_type start_idx);
196
197  // A container of BufferBlocks
198  Blocks blocks_;
199
200  // The default allocation size for a block.
201  // In general, blocksize_ bytes will be allocated for
202  // each buffer.
203  size_t blocksize_;
204
205  // If set to true, then the first block cannot be used for Write() calls as
206  // the WriteToContiguous... function will modify the base pointer for this
207  // block, and the Write() calls need to be sure that the base pointer will
208  // not be changing in order to provide the user with StringPieces which
209  // continue to be valid.
210  bool can_write_to_contiguous_buffer_;
211};
212
213////////////////////////////////////////////////////////////////////////////////
214
215// All of the functions in the BalsaHeaders class use string pieces, by either
216// using the StringPiece class, or giving an explicit size and char* (as these
217// are the native representation for these string pieces).
218// This is done for several reasons.
219//  1) This minimizes copying/allocation/deallocation as compared to using
220//  string parameters
221//  2) This reduces the number of strlen() calls done (as the length of any
222//  string passed in is relatively likely to be known at compile time, and for
223//  those strings passed back we obviate the need for a strlen() to determine
224//  the size of new storage allocations if a new allocation is required.
225//  3) This class attempts to store all of its data in two linear buffers in
226//  order to enhance the speed of parsing and writing out to a buffer. As a
227//  result, many string pieces are -not- terminated by '\0', and are not
228//  c-strings.  Since this is the case, we must delineate the length of the
229//  string explicitly via a length.
230//
231//  WARNING:  The side effect of using StringPiece is that if the underlying
232//  buffer changes (due to modifying the headers) the StringPieces which point
233//  to the data which was modified, may now contain "garbage", and should not
234//  be dereferenced.
235//  For example, If you fetch some component of the first-line, (request or
236//  response), and then you modify the first line, the StringPieces you
237//  originally received from the original first-line may no longer be valid).
238//
239//  StringPieces pointing to pieces of header lines which have not been
240//  erased() or modified should be valid until the object is cleared or
241//  destroyed.
242
243class BalsaHeaders {
244 public:
245  struct HeaderLineDescription {
246    HeaderLineDescription(size_t first_character_index,
247                          size_t key_end_index,
248                          size_t value_begin_index,
249                          size_t last_character_index,
250                          size_t buffer_base_index) :
251        first_char_idx(first_character_index),
252        key_end_idx(key_end_index),
253        value_begin_idx(value_begin_index),
254        last_char_idx(last_character_index),
255        buffer_base_idx(buffer_base_index),
256        skip(false) {}
257
258    HeaderLineDescription() :
259        first_char_idx(0),
260        key_end_idx(0),
261        value_begin_idx(0),
262        last_char_idx(0),
263        buffer_base_idx(0),
264        skip(false) {}
265
266    size_t first_char_idx;
267    size_t key_end_idx;
268    size_t value_begin_idx;
269    size_t last_char_idx;
270    BalsaBuffer::Blocks::size_type buffer_base_idx;
271    bool skip;
272  };
273
274  typedef std::vector<base::StringPiece> HeaderTokenList;
275  friend bool ParseHTTPFirstLine(const char* begin,
276                                 const char* end,
277                                 bool is_request,
278                                 size_t max_request_uri_length,
279                                 BalsaHeaders* headers,
280                                 BalsaFrameEnums::ErrorCode* error_code);
281
282 protected:
283  typedef std::vector<HeaderLineDescription> HeaderLines;
284
285  // Why these base classes (iterator_base, reverse_iterator_base)?  Well, if
286  // we do want to export both iterator and const_iterator types (currently we
287  // only have const_iterator), then this is useful to avoid code duplication.
288  // Additionally, having this base class makes comparisons of iterators of
289  // different types (they're different types to ensure that operator= and
290  // constructors do not work in the places where they're expected to not work)
291  // work properly. There could be as many as 4 iterator types, all based on
292  // the same data as iterator_base... so it makes sense to simply have some
293  // base classes.
294
295  class iterator_base {
296   public:
297    friend class BalsaHeaders;
298    friend class reverse_iterator_base;
299    typedef std::pair<base::StringPiece, base::StringPiece> StringPiecePair;
300    typedef StringPiecePair value_type;
301    typedef value_type& reference;
302    typedef value_type* pointer;
303
304    typedef std::forward_iterator_tag iterator_category;
305    typedef ptrdiff_t difference_type;
306
307    typedef iterator_base self;
308
309    // default constructor.
310    iterator_base();
311
312    // copy constructor.
313    iterator_base(const iterator_base& it);
314
315    reference operator*() const {
316      return Lookup(idx_);
317    }
318
319    pointer operator->() const {
320      return &(this->operator*());
321    }
322
323    bool operator==(const self& it) const {
324      return idx_ == it.idx_;
325    }
326
327    bool operator<(const self& it) const {
328      return idx_ < it.idx_;
329    }
330
331    bool operator<=(const self& it) const {
332      return idx_ <= it.idx_;
333    }
334
335    bool operator!=(const self& it) const {
336      return !(*this == it);
337    }
338
339    bool operator>(const self& it) const {
340      return it < *this;
341    }
342
343    bool operator>=(const self& it) const {
344      return it <= *this;
345    }
346
347    // This mainly exists so that we can have interesting output for
348    // unittesting. The EXPECT_EQ, EXPECT_NE functions require that
349    // operator<< work for the classes it sees.  It would be better if there
350    // was an additional traits-like system for the gUnit output... but oh
351    // well.
352    std::ostream& operator<<(std::ostream& os) const;
353
354   protected:
355    iterator_base(const BalsaHeaders* headers, HeaderLines::size_type index);
356
357    void increment() {
358      const HeaderLines& header_lines = headers_->header_lines_;
359      const HeaderLines::size_type header_lines_size = header_lines.size();
360      const HeaderLines::size_type original_idx = idx_;
361      do {
362        ++idx_;
363      } while (idx_ < header_lines_size && header_lines[idx_].skip == true);
364      // The condition below exists so that ++(end() - 1) == end(), even
365      // if there are only 'skip == true' elements between the end() iterator
366      // and the end of the vector of HeaderLineDescriptions.
367      // TODO(fenix): refactor this list so that we don't have to do
368      // linear scanning through skipped headers (and this condition is
369      // then unnecessary)
370      if (idx_ == header_lines_size) {
371        idx_ = original_idx + 1;
372      }
373    }
374
375    void decrement() {
376      const HeaderLines& header_lines = headers_->header_lines_;
377      const HeaderLines::size_type header_lines_size = header_lines.size();
378      const HeaderLines::size_type original_idx = idx_;
379      do {
380        --idx_;
381      } while (idx_ < header_lines_size && header_lines[idx_].skip == true);
382      // The condition below exists so that --(rbegin() + 1) == rbegin(), even
383      // if there are only 'skip == true' elements between the rbegin() iterator
384      // and the beginning of the vector of HeaderLineDescriptions.
385      // TODO(fenix): refactor this list so that we don't have to do
386      // linear scanning through skipped headers (and this condition is
387      // then unnecessary)
388      if (idx_ > header_lines_size) {
389        idx_ = original_idx - 1;
390      }
391    }
392
393    reference Lookup(HeaderLines::size_type index) const {
394      DCHECK_LT(index, headers_->header_lines_.size());
395      const HeaderLineDescription& line = headers_->header_lines_[index];
396      const char* stream_begin = headers_->GetPtr(line.buffer_base_idx);
397      value_ = value_type(
398          base::StringPiece(stream_begin + line.first_char_idx,
399                      line.key_end_idx - line.first_char_idx),
400          base::StringPiece(stream_begin + line.value_begin_idx,
401                      line.last_char_idx - line.value_begin_idx));
402      DCHECK_GE(line.key_end_idx, line.first_char_idx);
403      DCHECK_GE(line.last_char_idx, line.value_begin_idx);
404      return value_;
405    }
406
407    const BalsaHeaders* headers_;
408    HeaderLines::size_type idx_;
409    mutable StringPiecePair value_;
410  };
411
412  class reverse_iterator_base : public iterator_base {
413   public:
414    typedef reverse_iterator_base self;
415    typedef iterator_base::reference reference;
416    typedef iterator_base::pointer pointer;
417    using iterator_base::headers_;
418    using iterator_base::idx_;
419
420    reverse_iterator_base() : iterator_base() {}
421
422    // This constructor is no explicit purposely.
423    reverse_iterator_base(const iterator_base& it) :  // NOLINT
424        iterator_base(it) {
425    }
426
427    self& operator=(const iterator_base& it) {
428      idx_ = it.idx_;
429      headers_ = it.headers_;
430      return *this;
431    }
432
433    self& operator=(const reverse_iterator_base& it) {
434      idx_ = it.idx_;
435      headers_ = it.headers_;
436      return *this;
437    }
438
439    reference operator*() const {
440      return Lookup(idx_ - 1);
441    }
442
443    pointer operator->() const {
444      return &(this->operator*());
445    }
446
447    reverse_iterator_base(const reverse_iterator_base& it) :
448        iterator_base(it) { }
449
450   protected:
451    void increment() {
452      --idx_;
453      iterator_base::decrement();
454      ++idx_;
455    }
456
457    void decrement() {
458      ++idx_;
459      iterator_base::increment();
460      --idx_;
461    }
462
463    reverse_iterator_base(const BalsaHeaders* headers,
464                          HeaderLines::size_type index) :
465        iterator_base(headers, index) {}
466  };
467
468 public:
469  class const_header_lines_iterator : public iterator_base {
470    friend class BalsaHeaders;
471   public:
472    typedef const_header_lines_iterator self;
473    const_header_lines_iterator() : iterator_base() {}
474
475    const_header_lines_iterator(const const_header_lines_iterator& it) :
476        iterator_base(it.headers_, it.idx_) {}
477
478    self& operator++() {
479      iterator_base::increment();
480      return *this;
481    }
482
483    self& operator--() {
484      iterator_base::decrement();
485      return *this;
486    }
487   protected:
488    const_header_lines_iterator(const BalsaHeaders* headers,
489                                HeaderLines::size_type index) :
490        iterator_base(headers, index) {}
491  };
492
493  class const_reverse_header_lines_iterator : public reverse_iterator_base {
494   public:
495    typedef const_reverse_header_lines_iterator self;
496    const_reverse_header_lines_iterator() : reverse_iterator_base() {}
497
498    const_reverse_header_lines_iterator(
499      const const_header_lines_iterator& it) :
500        reverse_iterator_base(it.headers_, it.idx_) {}
501
502    const_reverse_header_lines_iterator(
503      const const_reverse_header_lines_iterator& it) :
504        reverse_iterator_base(it.headers_, it.idx_) {}
505
506    const_header_lines_iterator base() {
507      return const_header_lines_iterator(headers_, idx_);
508    }
509
510    self& operator++() {
511      reverse_iterator_base::increment();
512      return *this;
513    }
514
515    self& operator--() {
516      reverse_iterator_base::decrement();
517      return *this;
518    }
519   protected:
520    const_reverse_header_lines_iterator(const BalsaHeaders* headers,
521                                        HeaderLines::size_type index) :
522        reverse_iterator_base(headers, index) {}
523
524    friend class BalsaHeaders;
525  };
526
527  // An iterator that only stops at lines with a particular key.
528  // See also GetIteratorForKey.
529  //
530  // Check against header_lines_key_end() to determine when iteration is
531  // finished. header_lines_end() will also work.
532  class const_header_lines_key_iterator : public iterator_base {
533    friend class BalsaHeaders;
534   public:
535    typedef const_header_lines_key_iterator self;
536    const_header_lines_key_iterator(const const_header_lines_key_iterator&);
537
538    self& operator++() {
539      do {
540        iterator_base::increment();
541      } while (!AtEnd() &&
542               !StringPieceUtils::EqualIgnoreCase(key_, (**this).first));
543      return *this;
544    }
545
546    void operator++(int ignore) {
547      ++(*this);
548    }
549
550    // Only forward-iteration makes sense, so no operator-- defined.
551
552   private:
553    const_header_lines_key_iterator(const BalsaHeaders* headers,
554                                    HeaderLines::size_type index,
555                                    const base::StringPiece& key);
556
557    // Should only be used for creating an end iterator.
558    const_header_lines_key_iterator(const BalsaHeaders* headers,
559                                    HeaderLines::size_type index);
560
561    bool AtEnd() const {
562      return *this >= headers_->header_lines_end();
563    }
564
565    base::StringPiece key_;
566  };
567
568  // TODO(fenix): Revisit the amount of bytes initially allocated to the second
569  // block of the balsa_buffer_. It may make sense to pre-allocate some amount
570  // (roughly the amount we'd append in new headers such as X-User-Ip, etc.)
571  BalsaHeaders();
572  ~BalsaHeaders();
573
574  const_header_lines_iterator header_lines_begin() {
575    return HeaderLinesBeginHelper<const_header_lines_iterator>();
576  }
577
578  const_header_lines_iterator header_lines_begin() const {
579    return HeaderLinesBeginHelper<const_header_lines_iterator>();
580  }
581
582  const_header_lines_iterator header_lines_end() {
583    return HeaderLinesEndHelper<const_header_lines_iterator>();
584  }
585
586  const_header_lines_iterator header_lines_end() const {
587    return HeaderLinesEndHelper<const_header_lines_iterator>();
588  }
589
590  const_reverse_header_lines_iterator header_lines_rbegin() {
591    return const_reverse_header_lines_iterator(header_lines_end());
592  }
593
594  const_reverse_header_lines_iterator header_lines_rbegin() const {
595    return const_reverse_header_lines_iterator(header_lines_end());
596  }
597
598  const_reverse_header_lines_iterator header_lines_rend() {
599    return const_reverse_header_lines_iterator(header_lines_begin());
600  }
601
602  const_reverse_header_lines_iterator header_lines_rend() const {
603    return const_reverse_header_lines_iterator(header_lines_begin());
604  }
605
606  const_header_lines_key_iterator header_lines_key_end() const {
607    return HeaderLinesEndHelper<const_header_lines_key_iterator>();
608  }
609
610  void erase(const const_header_lines_iterator& it) {
611    DCHECK_EQ(it.headers_, this);
612    DCHECK_LT(it.idx_, header_lines_.size());
613    DCHECK_GE(it.idx_, 0u);
614    header_lines_[it.idx_].skip = true;
615  }
616
617  void Clear();
618
619  void Swap(BalsaHeaders* other);
620
621  void CopyFrom(const BalsaHeaders& other);
622
623  void HackHeader(const base::StringPiece& key, const base::StringPiece& value);
624
625  // Same as AppendToHeader, except that it will attempt to preserve
626  // header ordering.
627  // Note that this will always append to an existing header, if available,
628  // without moving the header around, or collapsing multiple header lines
629  // with the same key together. For this reason, it only 'attempts' to
630  // preserve header ordering.
631  // TODO(fenix): remove this function and rename all occurances
632  // of it in the code to AppendToHeader when the condition above
633  // has been satisified.
634  void HackAppendToHeader(const base::StringPiece& key,
635                          const base::StringPiece& value);
636
637  // Replaces header entries with key 'key' if they exist, or appends
638  // a new header if none exist.  See 'AppendHeader' below for additional
639  // comments about ContentLength and TransferEncoding headers. Note that this
640  // will allocate new storage every time that it is called.
641  // TODO(fenix): modify this function to reuse existing storage
642  // if it is available.
643  void ReplaceOrAppendHeader(const base::StringPiece& key,
644                             const base::StringPiece& value);
645
646  // Append a new header entry to the header object. Clients who wish to append
647  // Content-Length header should use SetContentLength() method instead of
648  // adding the content length header using AppendHeader (manually adding the
649  // content length header will not update the content_length_ and
650  // content_length_status_ values).
651  // Similarly, clients who wish to add or remove the transfer encoding header
652  // in order to apply or remove chunked encoding should use SetChunkEncoding()
653  // instead.
654  void AppendHeader(const base::StringPiece& key,
655                    const base::StringPiece& value);
656
657  // Appends ',value' to an existing header named 'key'.  If no header with the
658  // correct key exists, it will call AppendHeader(key, value).  Calling this
659  // function on a key which exists several times in the headers will produce
660  // unpredictable results.
661  void AppendToHeader(const base::StringPiece& key,
662                      const base::StringPiece& value);
663
664  // Prepends 'value,' to an existing header named 'key'.  If no header with the
665  // correct key exists, it will call AppendHeader(key, value).  Calling this
666  // function on a key which exists several times in the headers will produce
667  // unpredictable results.
668  void PrependToHeader(const base::StringPiece& key,
669                       const base::StringPiece& value);
670
671  const base::StringPiece GetHeader(const base::StringPiece& key) const;
672
673  // Iterates over all currently valid header lines, appending their
674  // values into the vector 'out', in top-to-bottom order.
675  // Header-lines which have been erased are not currently valid, and
676  // will not have their values appended. Empty values will be
677  // represented as empty string. If 'key' doesn't exist in the headers at
678  // all, out will not be changed. We do not clear the vector out
679  // before adding new entries. If there are header lines with matching
680  // key but empty value then they are also added to the vector out.
681  // (Basically empty values are not treated in any special manner).
682  //
683  // Example:
684  // Input header:
685  // "GET / HTTP/1.0\r\n"
686  //    "key1: v1\r\n"
687  //    "key1: \r\n"
688  //    "key1:\r\n"
689  //    "key1:  v1\r\n"
690  //    "key1:v2\r\n"
691  //
692  //  vector out is initially: ["foo"]
693  //  vector out after GetAllOfHeader("key1", &out) is:
694  // ["foo", "v1", "", "", "v2", "v1", "v2"]
695
696  void GetAllOfHeader(const base::StringPiece& key,
697                      std::vector<base::StringPiece>* out) const;
698
699  // Joins all values for key into a comma-separated string in out.
700  // More efficient than calling JoinStrings on result of GetAllOfHeader if
701  // you don't need the intermediate vector<StringPiece>.
702  void GetAllOfHeaderAsString(const base::StringPiece& key,
703                              std::string* out) const;
704
705  // Returns true if RFC 2616 Section 14 indicates that header can
706  // have multiple values.
707  static bool IsMultivaluedHeader(const base::StringPiece& header);
708
709  // Determine if a given header is present.
710  inline bool HasHeader(const base::StringPiece& key) const {
711    return (GetConstHeaderLinesIterator(key, header_lines_.begin()) !=
712            header_lines_.end());
713  }
714
715  // Returns true iff any header 'key' exists with non-empty value.
716  bool HasNonEmptyHeader(const base::StringPiece& key) const;
717
718  const_header_lines_iterator GetHeaderPosition(
719      const base::StringPiece& key) const;
720
721  // Returns a forward-only iterator that only stops at lines matching key.
722  // String backing 'key' must remain valid for lifetime of iterator.
723  //
724  // Check returned iterator against header_lines_key_end() to determine when
725  // iteration is finished.
726  const_header_lines_key_iterator GetIteratorForKey(
727      const base::StringPiece& key) const;
728
729  void RemoveAllOfHeader(const base::StringPiece& key);
730
731  // Removes all headers starting with 'key' [case insensitive]
732  void RemoveAllHeadersWithPrefix(const base::StringPiece& key);
733
734  // Returns the lower bound of memory  used by this header object, including
735  // all internal buffers and data structure. Some of the memory used cannot be
736  // directly measure. For example, memory used for bookkeeping by standard
737  // containers.
738  size_t GetMemoryUsedLowerBound() const;
739
740  // Returns the upper bound on the required buffer space to fully write out
741  // the header object (this include the first line, all header lines, and the
742  // final CRLF that marks the ending of the header).
743  size_t GetSizeForWriteBuffer() const;
744
745  // The following WriteHeader* methods are template member functions that
746  // place one requirement on the Buffer class: it must implement a Write
747  // method that takes a pointer and a length. The buffer passed in is not
748  // required to be stretchable. For non-stretchable buffers, the user must
749  // call GetSizeForWriteBuffer() to find out the upper bound on the output
750  // buffer space required to make sure that the entire header is serialized.
751  // BalsaHeaders will not check that there is adequate space in the buffer
752  // object during the write.
753
754  // Writes the entire header and the final CRLF that marks the end of the HTTP
755  // header section to the buffer. After this method returns, no more header
756  // data should be written to the buffer.
757  template <typename Buffer>
758  void WriteHeaderAndEndingToBuffer(Buffer* buffer) const {
759    WriteToBuffer(buffer);
760    WriteHeaderEndingToBuffer(buffer);
761  }
762
763  // Writes the final CRLF to the buffer to terminate the HTTP header section.
764  // After this method returns, no more header data should be written to the
765  // buffer.
766  template <typename Buffer>
767  static void WriteHeaderEndingToBuffer(Buffer* buffer) {
768    buffer->Write("\r\n", 2);
769  }
770
771  // Writes the entire header to the buffer without the CRLF that terminates
772  // the HTTP header. This lets users append additional header lines using
773  // WriteHeaderLineToBuffer and then terminate the header with
774  // WriteHeaderEndingToBuffer as the header is serialized to the
775  // buffer, without having to first copy the header.
776  template <typename Buffer>
777  void WriteToBuffer(Buffer* buffer) const {
778    // write the first line.
779    const size_t firstline_len = whitespace_4_idx_ - non_whitespace_1_idx_;
780    const char* stream_begin = GetPtr(firstline_buffer_base_idx_);
781    buffer->Write(stream_begin + non_whitespace_1_idx_, firstline_len);
782    buffer->Write("\r\n", 2);
783    const HeaderLines::size_type end = header_lines_.size();
784    for (HeaderLines::size_type i = 0; i < end; ++i) {
785      const HeaderLineDescription& line = header_lines_[i];
786      if (line.skip) {
787        continue;
788      }
789      const char* line_ptr = GetPtr(line.buffer_base_idx);
790      WriteHeaderLineToBuffer(
791          buffer,
792          base::StringPiece(line_ptr + line.first_char_idx,
793                      line.key_end_idx - line.first_char_idx),
794          base::StringPiece(line_ptr + line.value_begin_idx,
795                      line.last_char_idx - line.value_begin_idx));
796    }
797  }
798
799  // Takes a header line in the form of a key/value pair and append it to the
800  // buffer. This function should be called after WriteToBuffer to
801  // append additional header lines to the header without copying the header.
802  // When the user is done with appending to the buffer,
803  // WriteHeaderEndingToBuffer must be used to terminate the HTTP
804  // header in the buffer. This method is a no-op if key is empty.
805  template <typename Buffer>
806  static void WriteHeaderLineToBuffer(Buffer* buffer,
807                                      const base::StringPiece& key,
808                                      const base::StringPiece& value) {
809    // if the key is empty, we don't want to write the rest because it
810    // will not be a well-formed header line.
811    if (!key.empty()) {
812      buffer->Write(key.data(), key.size());
813      buffer->Write(": ", 2);
814      buffer->Write(value.data(), value.size());
815      buffer->Write("\r\n", 2);
816    }
817  }
818
819  // Dump the textural representation of the header object to a string, which
820  // is suitable for writing out to logs. All CRLF will be printed out as \n.
821  // This function can be called on a header object in any state. Raw header
822  // data will be printed out if the header object is not completely parsed,
823  // e.g., when there was an error in the middle of parsing.
824  // The header content is appended to the string; the original content is not
825  // cleared.
826  void DumpToString(std::string* str) const;
827
828  const base::StringPiece first_line() const {
829    DCHECK_GE(whitespace_4_idx_, non_whitespace_1_idx_);
830    return base::StringPiece(BeginningOfFirstLine() + non_whitespace_1_idx_,
831                       whitespace_4_idx_ - non_whitespace_1_idx_);
832  }
833
834  // Returns the parsed value of the response code if it has been parsed.
835  // Guaranteed to return 0 when unparsed (though it is a much better idea to
836  // verify that the BalsaFrame had no errors while parsing).
837  // This may return response codes which are outside the normal bounds of
838  // HTTP response codes-- it is up to the user of this class to ensure that
839  // the response code is one which is interpretable.
840  size_t parsed_response_code() const { return parsed_response_code_; }
841
842  const base::StringPiece request_method() const {
843    DCHECK_GE(whitespace_2_idx_, non_whitespace_1_idx_);
844    return base::StringPiece(BeginningOfFirstLine() + non_whitespace_1_idx_,
845                       whitespace_2_idx_ - non_whitespace_1_idx_);
846  }
847
848  const base::StringPiece response_version() const {
849    // Note: There is no difference between request_method() and
850    // response_version(). They both could be called
851    // GetFirstTokenFromFirstline()... but that wouldn't be anywhere near as
852    // descriptive.
853    return request_method();
854  }
855
856  const base::StringPiece request_uri() const {
857    DCHECK_GE(whitespace_3_idx_, non_whitespace_2_idx_);
858    return base::StringPiece(BeginningOfFirstLine() + non_whitespace_2_idx_,
859                       whitespace_3_idx_ - non_whitespace_2_idx_);
860  }
861
862  const base::StringPiece response_code() const {
863    // Note: There is no difference between request_uri() and response_code().
864    // They both could be called GetSecondtTokenFromFirstline(), but, as noted
865    // in an earlier comment, that wouldn't be as descriptive.
866    return request_uri();
867  }
868
869  const base::StringPiece request_version() const {
870    DCHECK_GE(whitespace_4_idx_, non_whitespace_3_idx_);
871    return base::StringPiece(BeginningOfFirstLine() + non_whitespace_3_idx_,
872                       whitespace_4_idx_ - non_whitespace_3_idx_);
873  }
874
875  const base::StringPiece response_reason_phrase() const {
876    // Note: There is no difference between request_version() and
877    // response_reason_phrase(). They both could be called
878    // GetThirdTokenFromFirstline(), but, as noted in an earlier comment, that
879    // wouldn't be as descriptive.
880    return request_version();
881  }
882
883  // Note that SetFirstLine will not update the internal indices for the
884  // various bits of the first-line (and may set them all to zero).
885  // If you'd like to use the accessors for the various bits of the firstline,
886  // then you should use the Set* functions, or SetFirstlineFromStringPieces,
887  // below, instead.
888  //
889  void SetFirstlineFromStringPieces(const base::StringPiece& firstline_a,
890                                    const base::StringPiece& firstline_b,
891                                    const base::StringPiece& firstline_c);
892
893  void SetRequestFirstlineFromStringPieces(const base::StringPiece& method,
894                                           const base::StringPiece& uri,
895                                           const base::StringPiece& version) {
896    SetFirstlineFromStringPieces(method, uri, version);
897  }
898
899  void SetResponseFirstlineFromStringPieces(
900      const base::StringPiece& version,
901      const base::StringPiece& code,
902      const base::StringPiece& reason_phrase) {
903    SetFirstlineFromStringPieces(version, code, reason_phrase);
904  }
905
906  // These functions are exactly the same, except that their names are
907  // different. This is done so that the code using this class is more
908  // expressive.
909  void SetRequestMethod(const base::StringPiece& method);
910  void SetResponseVersion(const base::StringPiece& version);
911
912  void SetRequestUri(const base::StringPiece& uri);
913  void SetResponseCode(const base::StringPiece& code);
914  void set_parsed_response_code(size_t parsed_response_code) {
915    parsed_response_code_ = parsed_response_code;
916  }
917  void SetParsedResponseCodeAndUpdateFirstline(size_t parsed_response_code);
918
919  // These functions are exactly the same, except that their names are
920  // different. This is done so that the code using this class is more
921  // expressive.
922  void SetRequestVersion(const base::StringPiece& version);
923  void SetResponseReasonPhrase(const base::StringPiece& reason_phrase);
924
925  // The biggest problem with SetFirstLine is that we don't want to use a
926  // separate buffer for it.  The second biggest problem with it is that the
927  // first biggest problem requires that we store offsets into a buffer instead
928  // of pointers into a buffer. Cuteness aside, SetFirstLine doesn't parse
929  // the individual fields of the firstline, and so accessors to those fields
930  // will not work properly after calling SetFirstLine. If you want those
931  // accessors to work, use the Set* functions above this one.
932  // SetFirstLine is stuff useful, however, if all you care about is correct
933  // serialization with the rest of the header object.
934  void SetFirstLine(const base::StringPiece& line);
935
936  // Simple accessors to some of the internal state
937  bool transfer_encoding_is_chunked() const {
938    return transfer_encoding_is_chunked_;
939  }
940
941  static bool ResponseCodeImpliesNoBody(size_t code) {
942    // From HTTP spec section 6.1.1 all 1xx responses must not have a body,
943    // as well as 204 No Content and 304 Not Modified.
944    return ((code >= 100) && (code <= 199)) || (code == 204) || (code == 304);
945  }
946
947  // Note: never check this for requests. Nothing bad will happen if you do,
948  // but spec does not allow requests framed by connection close.
949  // TODO(vitaliyl): refactor.
950  bool is_framed_by_connection_close() const {
951    // We declare that response is framed by connection close if it has no
952    // content-length, no transfer encoding, and is allowed to have a body by
953    // the HTTP spec.
954    // parsed_response_code_ is 0 for requests, so ResponseCodeImpliesNoBody
955    // will return false.
956    return (content_length_status_ == BalsaHeadersEnums::NO_CONTENT_LENGTH) &&
957        !transfer_encoding_is_chunked_ &&
958        !ResponseCodeImpliesNoBody(parsed_response_code_);
959  }
960
961  size_t content_length() const { return content_length_; }
962  BalsaHeadersEnums::ContentLengthStatus content_length_status() const {
963    return content_length_status_;
964  }
965
966  // SetContentLength and SetChunkEncoding modifies the header object to use
967  // content-length and transfer-encoding headers in a consistent manner. They
968  // set all internal flags and status so client can get a consistent view from
969  // various accessors.
970  void SetContentLength(size_t length);
971  void SetChunkEncoding(bool chunk_encode);
972
973 protected:
974  friend class BalsaFrame;
975  friend class SpdyFrame;
976  friend class HTTPMessage;
977  friend class BalsaHeadersTokenUtils;
978
979  const char* BeginningOfFirstLine() const {
980    return GetPtr(firstline_buffer_base_idx_);
981  }
982
983  char* GetPtr(BalsaBuffer::Blocks::size_type block_idx) {
984    return balsa_buffer_.GetPtr(block_idx);
985  }
986
987  const char* GetPtr(BalsaBuffer::Blocks::size_type block_idx) const {
988    return balsa_buffer_.GetPtr(block_idx);
989  }
990
991  void WriteFromFramer(const char* ptr, size_t size) {
992    balsa_buffer_.WriteToContiguousBuffer(base::StringPiece(ptr, size));
993  }
994
995  void DoneWritingFromFramer() {
996    balsa_buffer_.NoMoreWriteToContiguousBuffer();
997  }
998
999  const char* OriginalHeaderStreamBegin() const {
1000    return balsa_buffer_.StartOfFirstBlock();
1001  }
1002
1003  const char* OriginalHeaderStreamEnd() const {
1004    return balsa_buffer_.EndOfFirstBlock();
1005  }
1006
1007  size_t GetReadableBytesFromHeaderStream() const {
1008    return OriginalHeaderStreamEnd() - OriginalHeaderStreamBegin();
1009  }
1010
1011  void GetReadablePtrFromHeaderStream(const char** p, size_t* s) {
1012    *p = OriginalHeaderStreamBegin();
1013    *s = GetReadableBytesFromHeaderStream();
1014  }
1015
1016  base::StringPiece GetValueFromHeaderLineDescription(
1017      const HeaderLineDescription& line) const;
1018
1019  void AddAndMakeDescription(const base::StringPiece& key,
1020                             const base::StringPiece& value,
1021                             HeaderLineDescription* d);
1022
1023  void AppendOrPrependAndMakeDescription(const base::StringPiece& key,
1024                                         const base::StringPiece& value,
1025                                         bool append,
1026                                         HeaderLineDescription* d);
1027
1028  // Removes all header lines with the given key starting at start.
1029  void RemoveAllOfHeaderStartingAt(const base::StringPiece& key,
1030                                   HeaderLines::iterator start);
1031
1032  // If the 'key' does not exist in the headers, calls
1033  // AppendHeader(key, value).  Otherwise if append is true, appends ',value'
1034  // to the first existing header with key 'key'.  If append is false, prepends
1035  // 'value,' to the first existing header with key 'key'.
1036  void AppendOrPrependToHeader(const base::StringPiece& key,
1037                               const base::StringPiece& value,
1038                               bool append);
1039
1040  HeaderLines::const_iterator GetConstHeaderLinesIterator(
1041      const base::StringPiece& key,
1042      HeaderLines::const_iterator start) const;
1043
1044  HeaderLines::iterator GetHeaderLinesIteratorNoSkip(
1045      const base::StringPiece& key,
1046      HeaderLines::iterator start);
1047
1048  HeaderLines::iterator GetHeaderLinesIterator(
1049      const base::StringPiece& key,
1050      HeaderLines::iterator start);
1051
1052  template <typename IteratorType>
1053  const IteratorType HeaderLinesBeginHelper() const {
1054    if (header_lines_.empty()) {
1055      return IteratorType(this, 0);
1056    }
1057    const HeaderLines::size_type header_lines_size = header_lines_.size();
1058    for (HeaderLines::size_type i = 0; i < header_lines_size; ++i) {
1059      if (header_lines_[i].skip == false) {
1060        return IteratorType(this, i);
1061      }
1062    }
1063    return IteratorType(this, 0);
1064  }
1065
1066  template <typename IteratorType>
1067  const IteratorType HeaderLinesEndHelper() const {
1068    if (header_lines_.empty()) {
1069      return IteratorType(this, 0);
1070    }
1071    const HeaderLines::size_type header_lines_size = header_lines_.size();
1072    HeaderLines::size_type i = header_lines_size;
1073    do {
1074      --i;
1075      if (header_lines_[i].skip == false) {
1076        return IteratorType(this, i + 1);
1077      }
1078    } while (i != 0);
1079    return IteratorType(this, 0);
1080  }
1081
1082  // At the moment, this function will always return the original headers.
1083  // In the future, it may not do so after erasing header lines, modifying
1084  // header lines, or modifying the first line.
1085  // For this reason, it is strongly suggested that use of this function is
1086  // only acceptable for the purpose of debugging parse errors seen by the
1087  // BalsaFrame class.
1088  base::StringPiece OriginalHeadersForDebugging() const {
1089    return base::StringPiece(OriginalHeaderStreamBegin(),
1090                       OriginalHeaderStreamEnd() - OriginalHeaderStreamBegin());
1091  }
1092
1093  BalsaBuffer balsa_buffer_;
1094
1095  size_t content_length_;
1096  BalsaHeadersEnums::ContentLengthStatus content_length_status_;
1097  size_t parsed_response_code_;
1098  // HTTP firstlines all have the following structure:
1099  //  LWS         NONWS  LWS    NONWS   LWS    NONWS   NOTCRLF  CRLF
1100  //  [\t \r\n]+ [^\t ]+ [\t ]+ [^\t ]+ [\t ]+ [^\t ]+ [^\r\n]+ "\r\n"
1101  //  ws1        nws1    ws2    nws2    ws3    nws3             ws4
1102  //  |          [-------)      [-------)      [----------------)
1103  //    REQ:     method         request_uri    version
1104  //   RESP:     version        statuscode     reason
1105  //
1106  //   The first NONWS->LWS component we'll call firstline_a.
1107  //   The second firstline_b, and the third firstline_c.
1108  //
1109  //   firstline_a goes from nws1 to (but not including) ws2
1110  //   firstline_b goes from nws2 to (but not including) ws3
1111  //   firstline_c goes from nws3 to (but not including) ws4
1112  //
1113  // In the code:
1114  //    ws1 == whitespace_1_idx_
1115  //   nws1 == non_whitespace_1_idx_
1116  //    ws2 == whitespace_2_idx_
1117  //   nws2 == non_whitespace_2_idx_
1118  //    ws3 == whitespace_3_idx_
1119  //   nws3 == non_whitespace_3_idx_
1120  //    ws4 == whitespace_4_idx_
1121  BalsaBuffer::Blocks::size_type firstline_buffer_base_idx_;
1122  size_t whitespace_1_idx_;
1123  size_t non_whitespace_1_idx_;
1124  size_t whitespace_2_idx_;
1125  size_t non_whitespace_2_idx_;
1126  size_t whitespace_3_idx_;
1127  size_t non_whitespace_3_idx_;
1128  size_t whitespace_4_idx_;
1129  size_t end_of_firstline_idx_;
1130
1131  bool transfer_encoding_is_chunked_;
1132
1133  HeaderLines header_lines_;
1134};
1135
1136}  // namespace net
1137
1138#endif  // NET_TOOLS_BALSA_BALSA_HEADERS_H_
1139