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/*
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 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.
*/
/**
* @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 */
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