aboutsummaryrefslogtreecommitdiff
path: root/src/transport/tcp_server_mst_legacy.c
blob: 868f64d7c8cb3e38798d9c32682560e359c717bc (plain) (blame)
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
/*
     This file is part of GNUnet.
     Copyright (C) 2010 GNUnet e.V.

     GNUnet is free software: you can redistribute it and/or modify it
     under the terms of the GNU Affero General Public License as published
     by the Free Software Foundation, either version 3 of the License,
     or (at your option) any later version.

     GNUnet is distributed in the hope that it will be useful, but
     WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Affero General Public License for more details.
    
     You should have received a copy of the GNU Affero General Public License
     along with this program.  If not, see <http://www.gnu.org/licenses/>.

     SPDX-License-Identifier: AGPL3.0-or-later
*/

/**
 * @file util/server_mst.c
 * @brief convenience functions for handling inbound message buffers
 * @author Christian Grothoff
 */

#include "platform.h"
#include "gnunet_util_lib.h"


#if HAVE_UNALIGNED_64_ACCESS
#define ALIGN_FACTOR 4
#else
#define ALIGN_FACTOR 8
#endif


/**
 * Handle to a message stream tokenizer.
 */
struct GNUNET_SERVER_MessageStreamTokenizer
{

  /**
   * Function to call on completed messages.
   */
  GNUNET_SERVER_MessageTokenizerCallback cb;

  /**
   * Closure for @e cb.
   */
  void *cb_cls;

  /**
   * Size of the buffer (starting at @e hdr).
   */
  size_t curr_buf;

  /**
   * How many bytes in buffer have we already processed?
   */
  size_t off;

  /**
   * How many bytes in buffer are valid right now?
   */
  size_t pos;

  /**
   * Beginning of the buffer.  Typed like this to force alignment.
   */
  struct GNUNET_MessageHeader *hdr;

};



/**
 * Create a message stream tokenizer.
 *
 * @param cb function to call on completed messages
 * @param cb_cls closure for @a cb
 * @return handle to tokenizer
 */
struct GNUNET_SERVER_MessageStreamTokenizer *
GNUNET_SERVER_mst_create (GNUNET_SERVER_MessageTokenizerCallback cb,
                          void *cb_cls)
{
  struct GNUNET_SERVER_MessageStreamTokenizer *ret;

  ret = GNUNET_new (struct GNUNET_SERVER_MessageStreamTokenizer);
  ret->hdr = GNUNET_malloc (GNUNET_MIN_MESSAGE_SIZE);
  ret->curr_buf = GNUNET_MIN_MESSAGE_SIZE;
  ret->cb = cb;
  ret->cb_cls = cb_cls;
  return ret;
}


/**
 * Add incoming data to the receive buffer and call the
 * callback for all complete messages.
 *
 * @param mst tokenizer to use
 * @param client_identity ID of client for which this is a buffer
 * @param buf input data to add
 * @param size number of bytes in @a buf
 * @param purge should any excess bytes in the buffer be discarded
 *       (i.e. for packet-based services like UDP)
 * @param one_shot only call callback once, keep rest of message in buffer
 * @return #GNUNET_OK if we are done processing (need more data)
 *         #GNUNET_NO if @a one_shot was set and we have another message ready
 *         #GNUNET_SYSERR if the data stream is corrupt
 */
int
GNUNET_SERVER_mst_receive (struct GNUNET_SERVER_MessageStreamTokenizer *mst,
                           void *client_identity,
                           const char *buf, size_t size,
                           int purge, int one_shot)
{
  const struct GNUNET_MessageHeader *hdr;
  size_t delta;
  uint16_t want;
  char *ibuf;
  int need_align;
  unsigned long offset;
  int ret;

  GNUNET_assert (mst->off <= mst->pos);
  GNUNET_assert (mst->pos <= mst->curr_buf);
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Server-mst receives %u bytes with %u bytes already in private buffer\n",
       (unsigned int) size, (unsigned int) (mst->pos - mst->off));
  ret = GNUNET_OK;
  ibuf = (char *) mst->hdr;
  while (mst->pos > 0)
  {
do_align:
    GNUNET_assert (mst->pos >= mst->off);
    if ((mst->curr_buf - mst->off < sizeof (struct GNUNET_MessageHeader)) ||
        (0 != (mst->off % ALIGN_FACTOR)))
    {
      /* need to align or need more space */
      mst->pos -= mst->off;
      memmove (ibuf, &ibuf[mst->off], mst->pos);
      mst->off = 0;
    }
    if (mst->pos - mst->off < sizeof (struct GNUNET_MessageHeader))
    {
      delta =
          GNUNET_MIN (sizeof (struct GNUNET_MessageHeader) -
                      (mst->pos - mst->off), size);
      GNUNET_memcpy (&ibuf[mst->pos], buf, delta);
      mst->pos += delta;
      buf += delta;
      size -= delta;
    }
    if (mst->pos - mst->off < sizeof (struct GNUNET_MessageHeader))
    {
      if (purge)
      {
        mst->off = 0;
        mst->pos = 0;
      }
      return GNUNET_OK;
    }
    hdr = (const struct GNUNET_MessageHeader *) &ibuf[mst->off];
    want = ntohs (hdr->size);
    if (want < sizeof (struct GNUNET_MessageHeader))
    {
      GNUNET_break_op (0);
      return GNUNET_SYSERR;
    }
    if ( (mst->curr_buf - mst->off < want) &&
	 (mst->off > 0) )
    {
      /* can get more space by moving */
      mst->pos -= mst->off;
      memmove (ibuf, &ibuf[mst->off], mst->pos);
      mst->off = 0;
    }
    if (mst->curr_buf < want)
    {
      /* need to get more space by growing buffer */
      GNUNET_assert (0 == mst->off);
      mst->hdr = GNUNET_realloc (mst->hdr, want);
      ibuf = (char *) mst->hdr;
      mst->curr_buf = want;
    }
    hdr = (const struct GNUNET_MessageHeader *) &ibuf[mst->off];
    if (mst->pos - mst->off < want)
    {
      delta = GNUNET_MIN (want - (mst->pos - mst->off), size);
      GNUNET_assert (mst->pos + delta <= mst->curr_buf);
      GNUNET_memcpy (&ibuf[mst->pos], buf, delta);
      mst->pos += delta;
      buf += delta;
      size -= delta;
    }
    if (mst->pos - mst->off < want)
    {
      if (purge)
      {
        mst->off = 0;
        mst->pos = 0;
      }
      return GNUNET_OK;
    }
    if (one_shot == GNUNET_SYSERR)
    {
      /* cannot call callback again, but return value saying that
       * we have another full message in the buffer */
      ret = GNUNET_NO;
      goto copy;
    }
    if (one_shot == GNUNET_YES)
      one_shot = GNUNET_SYSERR;
    mst->off += want;
    if (GNUNET_SYSERR == mst->cb (mst->cb_cls, client_identity, hdr))
      return GNUNET_SYSERR;
    if (mst->off == mst->pos)
    {
      /* reset to beginning of buffer, it's free right now! */
      mst->off = 0;
      mst->pos = 0;
    }
  }
  GNUNET_assert (0 == mst->pos);
  while (size > 0)
  {
    LOG (GNUNET_ERROR_TYPE_DEBUG,
         "Server-mst has %u bytes left in inbound buffer\n",
         (unsigned int) size);
    if (size < sizeof (struct GNUNET_MessageHeader))
      break;
    offset = (unsigned long) buf;
    need_align = (0 != (offset % ALIGN_FACTOR)) ? GNUNET_YES : GNUNET_NO;
    if (GNUNET_NO == need_align)
    {
      /* can try to do zero-copy and process directly from original buffer */
      hdr = (const struct GNUNET_MessageHeader *) buf;
      want = ntohs (hdr->size);
      if (want < sizeof (struct GNUNET_MessageHeader))
      {
	GNUNET_break_op (0);
        mst->off = 0;
        return GNUNET_SYSERR;
      }
      if (size < want)
        break;                  /* or not: buffer incomplete, so copy to private buffer... */
      if (one_shot == GNUNET_SYSERR)
      {
        /* cannot call callback again, but return value saying that
         * we have another full message in the buffer */
        ret = GNUNET_NO;
        goto copy;
      }
      if (one_shot == GNUNET_YES)
        one_shot = GNUNET_SYSERR;
      if (GNUNET_SYSERR == mst->cb (mst->cb_cls, client_identity, hdr))
        return GNUNET_SYSERR;
      buf += want;
      size -= want;
    }
    else
    {
      /* need to copy to private buffer to align;
       * yes, we go a bit more spagetti than usual here */
      goto do_align;
    }
  }
copy:
  if ((size > 0) && (!purge))
  {
    if (size + mst->pos > mst->curr_buf)
    {
      mst->hdr = GNUNET_realloc (mst->hdr, size + mst->pos);
      ibuf = (char *) mst->hdr;
      mst->curr_buf = size + mst->pos;
    }
    GNUNET_assert (size + mst->pos <= mst->curr_buf);
    GNUNET_memcpy (&ibuf[mst->pos], buf, size);
    mst->pos += size;
  }
  if (purge)
  {
    mst->off = 0;
    mst->pos = 0;
  }
  LOG (GNUNET_ERROR_TYPE_DEBUG,
       "Server-mst leaves %u bytes in private buffer\n",
       (unsigned int) (mst->pos - mst->off));
  return ret;
}


/**
 * Destroys a tokenizer.
 *
 * @param mst tokenizer to destroy
 */
void
GNUNET_SERVER_mst_destroy (struct GNUNET_SERVER_MessageStreamTokenizer *mst)
{
  GNUNET_free (mst->hdr);
  GNUNET_free (mst);
}



/* end of server_mst.c */