-towards a new MST for the new service

1 files changed, 363 insertions, 0 deletions

diff --git a/src/util/mst.c b/src/util/mst.c
new file mode 100644
index 000000000..578ba8e04
--- /dev/null
+++ b/src/util/mst.c
@@ -0,0 +1,363 @@
+/*
+     This file is part of GNUnet.
+     Copyright (C) 2010, 2016 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, 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
+     General Public License for more details.
+
+     You should have received a copy of the GNU General Public License
+     along with GNUnet; see the file COPYING.  If not, write to the
+     Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+     Boston, MA 02110-1301, USA.
+*/
+
+/**
+ * @file util/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
+
+#define LOG(kind,...) GNUNET_log_from (kind, "util", __VA_ARGS__)
+
+
+/**
+ * Handle to a message stream tokenizer.
+ */
+struct GNUNET_MessageStreamTokenizer
+{
+
+  /**
+   * Function to call on completed messages.
+   */
+  GNUNET_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_MessageStreamTokenizer *
+GNUNET_MST_create (GNUNET_MessageTokenizerCallback cb,
+                   void *cb_cls)
+{
+  struct GNUNET_MessageStreamTokenizer *ret;
+
+  ret = GNUNET_new (struct GNUNET_MessageStreamTokenizer);
+  ret->hdr = GNUNET_malloc (GNUNET_SERVER_MIN_BUFFER_SIZE);
+  ret->curr_buf = GNUNET_SERVER_MIN_BUFFER_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 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_MST_from_buffer (struct GNUNET_MessageStreamTokenizer *mst,
+                        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,
+                                  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,
+                                    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;
+}
+
+
+/**
+ * Add incoming data to the receive buffer and call the
+ * callback for all complete messages.
+ *
+ * @param mst tokenizer to use
+ * @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 one_shot was set and we have another message ready
+ *         #GNUNET_SYSERR if the data stream is corrupt
+ */
+int
+GNUNET_MST_read (struct GNUNET_MessageStreamTokenizer *mst,
+                 struct GNUNET_NETWORK_Handle *sock,
+                 int purge,
+                 int one_shot)
+{
+  GNUNET_assert (0); // not implemented
+  return GNUNET_SYSERR;
+}
+
+
+/**
+ * Obtain the next message from the @a mst, assuming that
+ * there are more unprocessed messages in the internal buffer
+ * of the @a mst.
+ *
+ * @param mst tokenizer to use
+ * @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 one_shot was set and we have another message ready
+ *         #GNUNET_SYSERR if the data stream is corrupt
+ */
+int
+GNUNET_MST_next (struct GNUNET_MessageStreamTokenizer *mst,
+                 int one_shot)
+{
+  return GNUNET_MST_from_buffer (mst,
+                                 NULL,
+                                 0,
+                                 GNUNET_NO,
+                                 one_shot);
+}
+
+
+/**
+ * Destroys a tokenizer.
+ *
+ * @param mst tokenizer to destroy
+ */
+void
+GNUNET_MST_destroy (struct GNUNET_MessageStreamTokenizer *mst)
+{
+  GNUNET_free (mst->hdr);
+  GNUNET_free (mst);
+}
+
+
+
+/* end of server_mst.c */