aboutsummaryrefslogtreecommitdiff
path: root/web/apache/request.cxx
blob: 51590e34b78fca5c3d422e86915243ae5e456110 (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
// file      : web/apache/request.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
// license   : MIT; see accompanying LICENSE file

#include <web/apache/request.hxx>

#include <apr_tables.h>  // apr_table_*, apr_array_header_t
#include <apr_strings.h> // apr_pstrdup()

#include <httpd.h>         // request_rec, HTTP_*, OK
#include <http_protocol.h> // ap_*()

#include <strings.h> // strcasecmp(), strncasecmp()

#include <ctime>     // strftime(), time_t
#include <vector>
#include <chrono>
#include <memory>    // unique_ptr
#include <string>
#include <cassert>
#include <ostream>
#include <istream>
#include <cstring>   // str*(), memcpy(), size_t
#include <utility>   // move()
#include <stdexcept> // invalid_argument
#include <exception> // current_exception()
#include <streambuf>
#include <algorithm> // min()

#include <libbutl/optional.mxx>
#include <libbutl/timestamp.mxx>

#include <web/mime-url-encoding.hxx>

using namespace std;
using namespace butl;

namespace web
{
  namespace apache
  {
    // Extend the Apache stream with checking for the read limit and caching
    // the content if requested. Replay the cached content after rewind.
    //
    class istreambuf_cache: public istreambuf
    {
      enum class mode
      {
        cache,  // Read from Apache stream, save the read data into the cache.
        replay, // Read from the cache.
        proxy   // Read from Apache stream (don't save into the cache).
      };

    public:
      istreambuf_cache (size_t read_limit, size_t cache_limit,
                        request_rec* r,
                        stream_state& s,
                        size_t bufsize = 1024,
                        size_t putback = 1)
          : istreambuf (r, s, bufsize, putback),
            read_limit_ (read_limit),
            cache_limit_ (cache_limit)
      {
      }

      void
      rewind ()
      {
        // Fail if some content is already missed in the cache.
        //
        if (mode_ == mode::proxy)
          throw sequence_error (
            string ("web::apache::istreambuf_cache::rewind: ") +
            (cache_limit_ > 0
             ? "half-buffered"
             : "unbuffered"));

        mode_ = mode::replay;
        replay_pos_ = 0;
        setg (nullptr, nullptr, nullptr);
      }

      void
      limits (size_t read_limit, size_t cache_limit)
      {
        if (read_limit > 0)
          read_limit_ = read_limit;

        if (cache_limit > 0)
        {
          // We can not increase the cache limit if some content is already
          // missed in the cache.
          //
          if (cache_limit > cache_limit_ && mode_ == mode::proxy)
            throw sequence_error (
              "web::apache::istreambuf_cache::limits: unbuffered");

          cache_limit_ = cache_limit;
        }
      }

      size_t read_limit  () const noexcept {return read_limit_;}
      size_t cache_limit () const noexcept {return cache_limit_;}

    private:
      virtual int_type
      underflow ();

    private:
      // Limits
      //
      size_t read_limit_;
      size_t cache_limit_;

      // State
      //
      mode mode_ = mode::cache;
      size_t read_bytes_ = 0;
      bool eof_ = false;        // End of Apache stream is reached.

      // Cache
      //
      struct chunk
      {
        vector<char> data;
        size_t offset;

        chunk (vector<char>&& d, size_t o): data (move (d)), offset (o) {}

        // Make the type move constructible-only to avoid copying of chunks on
        // vector growth.
        //
        chunk (chunk&&) = default;
      };

      vector<chunk> cache_;
      size_t cache_size_ = 0;
      size_t replay_pos_ = 0;
    };

    istreambuf_cache::int_type istreambuf_cache::
    underflow ()
    {
      if (gptr () < egptr ())
        return traits_type::to_int_type (*gptr ());

      if (mode_ == mode::replay)
      {
        if (replay_pos_ < cache_.size ())
        {
          chunk& ch (cache_[replay_pos_++]);
          char*  p  (ch.data.data ());
          setg (p, p + ch.offset, p + ch.data.size ());
          return traits_type::to_int_type (*gptr ());
        }

        // No more data to replay, so switch to the cache mode. That includes
        // resetting eback, gptr and egptr, so they point into the istreambuf's
        // internal buffer. Putback area should also be restored.
        //
        mode_ = mode::cache;

        // Bailout if the end of stream is reached.
        //
        if (eof_)
          return traits_type::eof ();

        char* p (buf_.data () + putback_);
        size_t pb (0);

        // Restore putback area if there is any cached data. Thanks to
        // istreambuf, it's all in a single chunk.
        //
        if (!cache_.empty ())
        {
          chunk& ch (cache_.back ());
          pb = min (putback_, ch.data.size ());
          memcpy (p - pb, ch.data.data () + ch.data.size () - pb, pb);
        }

        setg (p - pb, p, p);
      }

      // Delegate reading to the base class in the cache or proxy modes, but
      // check for the read limit first.
      //
      if (read_limit_ && read_bytes_ >= read_limit_)
        throw invalid_request (HTTP_REQUEST_ENTITY_TOO_LARGE,
                               "payload too large");

      // Throws the sequence_error exception if some unbuffered content is
      // already written.
      //
      int_type r (istreambuf::underflow ());

      if (r == traits_type::eof ())
      {
        eof_ = true;
        return r;
      }

      // Increment the read bytes counter.
      //
      size_t rb (egptr () - gptr ());
      read_bytes_ += rb;

      // In the cache mode save the read data if the cache limit is not
      // reached, otherwise switch to the proxy mode.
      //
      if (mode_ == mode::cache)
      {
        // Not to complicate things we will copy the buffer into the cache
        // together with the putback area, which is OK as it usually takes a
        // small fraction of the buffer. By the same reason we will cache the
        // whole data read even though we can exceed the limits by
        // bufsize - putback - 1 bytes.
        //
        if (cache_size_ < cache_limit_)
        {
          chunk ch (vector<char> (eback (), egptr ()),
                    static_cast<size_t> (gptr () - eback ()));

          cache_.emplace_back (move (ch));
          cache_size_ += rb;
        }
        else
          mode_ = mode::proxy;
      }

      return r;
    }

    // request
    //
    request::
    request (request_rec* rec) noexcept
      : rec_ (rec)
    {
      rec_->status = HTTP_OK;
    }

    request::
    ~request ()
    {
    }

    void request::
    state (request_state s)
    {
      assert (s != request_state::initial);

      if (s == state_)
        return; // Noop.

      if (s < state_)
      {
        // Can't "unwind" irrevocable interaction with Apache API.
        //
        static const char* names[] = {
          "initial", "reading", "headers", "writing"};

        string str ("web::apache::request::set_state: ");
        str += names[static_cast<size_t> (state_)];
        str += " to ";
        str += names[static_cast<size_t> (s)];

        throw sequence_error (move (str));
      }

      if (s == request_state::reading)
      {
        // Prepare request content for reading.
        //
        int r (ap_setup_client_block (rec_, REQUEST_CHUNKED_DECHUNK));

        if (r != OK)
          throw invalid_request (r);
      }
      else if (s > request_state::reading && state_ <= request_state::reading)
      {
        // Read request content if any, discard whatever is received.
        //
        int r (ap_discard_request_body (rec_));

        if (r != OK)
          throw invalid_request (r);
      }

      state_ = s;
    }

    void request::
    rewind ()
    {
      // @@ Response cookies buffering is not supported yet. When done will be
      //    possible to rewind in broader range of cases.
      //
      if (state_ > request_state::reading)
        throw sequence_error ("web::apache::request::rewind: unbuffered");

      out_.reset ();
      out_buf_.reset ();

      rec_->status = HTTP_OK;

      ap_set_content_type (rec_, nullptr); // Unset the output content type.

      if (in_ != nullptr)
        rewind_istream ();
    }

    void request::
    rewind_istream ()
    {
      assert (in_buf_ != nullptr && in_ != nullptr);

      in_buf_->rewind (); // Throws if impossible to rewind.
      in_->clear ();      // Clears *bit flags (in particular eofbit).
    }

    istream& request::
    content (size_t limit, size_t buffer)
    {
      // Create the input stream/streambuf if not present, otherwise adjust the
      // limits.
      //
      if (in_ == nullptr)
      {
        unique_ptr<istreambuf_cache> in_buf (
          new istreambuf_cache (limit, buffer, rec_, *this));

        in_.reset (new istream (in_buf.get ()));
        in_buf_ = move (in_buf);
        in_->exceptions (istream::failbit | istream::badbit);

        // Save form data now otherwise will not be available to do later when
        // data is already read from stream.
        //
        form_data ();
      }
      else
      {
        assert (in_buf_ != nullptr);
        in_buf_->limits (limit, buffer);
      }

      return *in_;
    }

    const path& request::
    path ()
    {
      if (path_.empty ())
      {
        path_ = path_type (rec_->uri); // Is already URL-decoded.

        // Module request handler can not be called if URI is empty.
        //
        assert (!path_.empty ());
      }

      return path_;
    }

    const name_values& request::
    parameters ()
    {
      if (parameters_ == nullptr)
      {
        parameters_.reset (new name_values ());

        try
        {
          parse_parameters (rec_->args);
          parse_parameters (form_data ().c_str ());
        }
        catch (const invalid_argument& )
        {
          throw invalid_request ();
        }
      }

      return *parameters_;
    }

    const name_values& request::
    cookies ()
    {
      if (cookies_ == nullptr)
      {
        cookies_.reset (new name_values ());

        const apr_array_header_t* ha (apr_table_elts (rec_->headers_in));
        size_t n (ha->nelts);

        for (auto h (reinterpret_cast<const apr_table_entry_t *> (ha->elts));
             n--; ++h)
        {
          if (strcasecmp (h->key, "Cookie") == 0)
          {
            for (const char* n (h->val); n != nullptr; )
            {
              const char* v (strchr (n, '='));
              const char* e (strchr (n, ';'));

              if (e != nullptr && e < v)
                v = nullptr;

              string name (v != nullptr
                           ? mime_url_decode (n, v, true)
                           : (e
                              ? mime_url_decode (n, e, true)
                              : mime_url_decode (n, n + strlen (n), true)));

              optional<string> value;

              if (v++)
                value = e
                  ? mime_url_decode (v, e, true)
                  : mime_url_decode (v, v + strlen (v), true);

              if (!name.empty () || value)
                cookies_->emplace_back (move (name), move (value));

              n = e ? e + 1 : nullptr;
            }
          }
        }
      }

      return *cookies_;
    }

    ostream& request::
    content (status_code status, const string& type, bool buffer)
    {
      if (out_ &&

          // Same status code.
          //
          status == rec_->status &&

          // Same buffering flag.
          //
          buffer ==
          (dynamic_cast<stringbuf*> (out_buf_.get ()) != nullptr) &&

          // Same content type.
          //
          strcasecmp (rec_->content_type ? rec_->content_type : "",
                      type.c_str ()) == 0)
      {
        // No change, return the existing stream.
        //
        return *out_;
      }

      if (state_ >= request_state::writing)
        throw sequence_error ("web::apache::request::content");

      if (!buffer)
        // Request body will be discarded prior first byte of content is
        // written. Save form data now to make it available for future
        // parameters() call.
        //
        form_data ();

      unique_ptr<streambuf> out_buf (
        buffer
        ? static_cast<streambuf*> (new stringbuf ())
        : static_cast<streambuf*> (new ostreambuf (rec_, *this)));

      out_.reset (new ostream (out_buf.get ()));
      out_buf_ = move (out_buf);
      out_->exceptions (ostream::eofbit | ostream::failbit | ostream::badbit);

      rec_->status = status;

      ap_set_content_type (
        rec_,
        type.empty () ? nullptr : apr_pstrdup (rec_->pool, type.c_str ()));

      return *out_;
    }

    void request::
    status (status_code status)
    {
      if (status != rec_->status)
      {
        // Setting status code in exception handler is a common usecase
        // where no sense to throw but still need to signal apache a
        // proper status code.
        //
        if (state_ >= request_state::writing && !current_exception ())
          throw sequence_error ("web::apache::request::status");

        rec_->status = status;
        out_.reset ();
        out_buf_.reset ();
        ap_set_content_type (rec_, nullptr);
      }
    }

    void request::
    cookie (const char* name,
            const char* value,
            const chrono::seconds* max_age,
            const char* path,
            const char* domain,
            bool secure,
            bool buffer)
    {
      assert (!buffer); // Cookie buffering is not implemented yet.

      string s (mime_url_encode (name));
      s += "=";
      s += mime_url_encode (value);

      if (max_age)
      {
        timestamp tp (system_clock::now () + *max_age);
        time_t t (system_clock::to_time_t (tp));

        // Assume global locale is not changed and still "C".
        //
        char b[100];
        strftime (b, sizeof (b), "%a, %d-%b-%Y %H:%M:%S GMT", gmtime (&t));
        s += "; Expires=";
        s += b;
      }

      if (path)
      {
        s += ";Path=";
        s += path;
      }

      if (domain)
      {
        s += ";Domain=";
        s += domain;
      }

      if (secure)
        s += ";Secure";

      state (request_state::headers);
      apr_table_add (rec_->err_headers_out, "Set-Cookie", s.c_str ());
    }

    void request::
    parse_parameters (const char* args)
    {
      for (auto n (args); n != nullptr; )
      {
        const char* v (strchr (n, '='));
        const char* e (strchr (n, '&'));

        if (e != nullptr && e < v)
          v = nullptr;

        string name (v != nullptr
                     ? mime_url_decode (n, v) :
                     (e
                      ? mime_url_decode (n, e)
                      : mime_url_decode (n, n + strlen (n))));

        optional<string> value;

        if (v++)
          value = e
            ? mime_url_decode (v, e)
            : mime_url_decode (v, v + strlen (v));

        if (!name.empty () || value)
          parameters_->emplace_back (move (name), move (value));

        n = e ? e + 1 : nullptr;
      }
    }

    const string& request::
    form_data ()
    {
      if (!form_data_)
      {
        form_data_.reset (new string ());

        if (rec_->method_number == M_POST)
        {
          const char* ct (apr_table_get (rec_->headers_in, "Content-Type"));

          if (ct != nullptr &&
              strncasecmp ("application/x-www-form-urlencoded", ct, 33) == 0)
          {
            size_t limit  (0);
            bool   rewind (true);

            // Assign some reasonable (64K) input content read/cache limits if
            // not done explicitly yet (with the request::content() call).
            // Rewind afterwards unless the cache limit is set to zero.
            //
            if (in_buf_ == nullptr)
              limit = 64 * 1024;
            else
              rewind = in_buf_->cache_limit () > 0;

            istream& istr (content (limit, limit));

            // Do not throw when eofbit is set (end of stream reached), and
            // when failbit is set (getline() failed to extract any character).
            //
            istream::iostate e (istr.exceptions ()); // Save exception mask.
            istr.exceptions (istream::badbit);
            getline (istr, *form_data_);
            istr.exceptions (e);                     // Restore exception mask.

            // Rewind the stream unless no buffering were requested beforehand.
            //
            if (rewind)
              rewind_istream ();
          }
        }
      }

      return *form_data_;
    }
  }
}