1 files changed, 196 insertions, 0 deletions

diff --git a/src/gns/gns_util.c b/src/gns/gns_util.c
new file mode 100644
index 000000000..b2f5e1f38
--- /dev/null
+++ b/src/gns/gns_util.c
@@ -0,0 +1,196 @@
+#include "gns.h"
+
+/**
+ * Add a DNS name to the buffer at the given location.
+ *
+ * @param dst where to write the name
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the name (increment by bytes used)
+ *            must not be changed if there is an error
+ * @param name name to write
+ * @return GNUNET_SYSERR if 'name' is invalid
+ *         GNUNET_NO if 'name' did not fit
+ *         GNUNET_OK if 'name' was added to 'dst'
+ */
+static int
+add_name (char *dst,
+          size_t dst_len,
+          size_t *off,
+          const char *name)
+{
+  const char *dot;
+  size_t start;
+  size_t pos;
+  size_t len;
+
+  if (NULL == name)
+    return GNUNET_SYSERR;
+  start = *off;
+  if (start + strlen (name) + 2 > dst_len)
+    return GNUNET_NO;
+  pos = start;
+  do
+  {
+    dot = strchr (name, '.');
+    if (NULL == dot)
+      len = strlen (name);
+    else
+      len = dot - name;
+    if ( (len >= 64) || (len == 0) )
+      return GNUNET_NO; /* segment too long or empty */
+    dst[pos++] = (char) (uint8_t) len;
+    memcpy (&dst[pos], name, len);
+    pos += len;
+    name += len + 1; /* also skip dot */
+  }
+  while (NULL != dot);
+  dst[pos++] = '\0'; /* terminator */
+  *off = pos;
+  return GNUNET_OK;
+}
+
+/**
+ * Add an MX record to the buffer at the given location.
+ *
+ * @param dst where to write the mx record
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the mx information (increment by bytes used);
+ *            can also change if there was an error
+ * @param mx mx information to write
+ * @return GNUNET_SYSERR if 'mx' is invalid
+ *         GNUNET_NO if 'mx' did not fit
+ *         GNUNET_OK if 'mx' was added to 'dst'
+ */
+static int
+add_mx (char *dst,
+        size_t dst_len,
+        size_t *off,
+        const struct GNUNET_DNSPARSER_MxRecord *mx)
+{
+  uint16_t mxpref;
+
+  if (*off + sizeof (uint16_t) > dst_len)
+    return GNUNET_NO;
+  mxpref = htons (mx->preference);
+  memcpy (&dst[*off], &mxpref, sizeof (mxpref));
+  (*off) += sizeof (mxpref);
+  return add_name (dst, dst_len, off, mx->mxhost);
+}
+
+
+/**
+ * Add an SOA record to the buffer at the given location.
+ *
+ * @param dst where to write the SOA record
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the SOA information (increment by bytes used)
+ *            can also change if there was an error
+ * @param soa SOA information to write
+ * @return GNUNET_SYSERR if 'soa' is invalid
+ *         GNUNET_NO if 'soa' did not fit
+ *         GNUNET_OK if 'soa' was added to 'dst'
+ */
+static int
+add_soa (char *dst,
+         size_t dst_len,
+         size_t *off,
+         const struct GNUNET_DNSPARSER_SoaRecord *soa)
+{
+  struct soa_data sd;
+  int ret;
+
+  if ( (GNUNET_OK != (ret = add_name (dst,
+                                      dst_len,
+                                      off,
+                                      soa->mname))) ||
+       (GNUNET_OK != (ret = add_name (dst,
+                                      dst_len,
+                                      off,
+                                      soa->rname)) ) )
+    return ret;
+  if (*off + sizeof (struct soa_data) > dst_len)
+    return GNUNET_NO;
+  sd.serial = htonl (soa->serial);
+  sd.refresh = htonl (soa->refresh);
+  sd.retry = htonl (soa->retry);
+  sd.expire = htonl (soa->expire);
+  sd.minimum = htonl (soa->minimum_ttl);
+  memcpy (&dst[*off], &sd, sizeof (sd));
+  (*off) += sizeof (sd);
+  return GNUNET_OK;
+}
+
+/**
+ * Add a DNS record to the buffer at the given location.
+ *
+ * @param dst where to write the record
+ * @param dst_len number of bytes in dst
+ * @param off pointer to offset where to write the query (increment by bytes used)
+ *            must not be changed if there is an error
+ * @param record record to write
+ * @return GNUNET_SYSERR if 'record' is invalid
+ *         GNUNET_NO if 'record' did not fit
+ *         GNUNET_OK if 'record' was added to 'dst'
+ */
+static int
+parse_record (char *dst,
+            size_t dst_len,
+            size_t *off,
+            const struct GNUNET_GNS_Record *record)
+{
+  int ret;
+  size_t start;
+  size_t pos;
+  struct record_line rl;
+
+  start = *off;
+  ret = add_name (dst, dst_len - sizeof (struct record_line), off, record->name);
+  if (ret != GNUNET_OK)
+    return ret;
+  /* '*off' is now the position where we will need to write the record line */
+
+  pos = *off + sizeof (struct record_line);
+  switch (record->type)
+  { 
+  case GNUNET_DNSPARSER_TYPE_MX:
+    ret = add_mx (dst, dst_len, &pos, record->data.mx);    
+    break;
+  case GNUNET_DNSPARSER_TYPE_SOA:
+    ret = add_soa (dst, dst_len, &pos, record->data.soa);
+    break;
+  case GNUNET_DNSPARSER_TYPE_NS:
+  case GNUNET_DNSPARSER_TYPE_CNAME:
+  case GNUNET_DNSPARSER_TYPE_PTR:
+    ret = add_name (dst, dst_len, &pos, record->data.hostname);
+    break;
+  default:
+    if (pos + record->data.raw.data_len > dst_len)
+    {
+      ret = GNUNET_NO;
+      break;
+    }
+    memcpy (&dst[pos], record->data.raw.data, record->data.raw.data_len);
+    pos += record->data.raw.data_len;
+    ret = GNUNET_OK;
+    break;
+  }
+  if (ret != GNUNET_OK)
+  {
+    *off = start;
+    return GNUNET_NO;
+  }
+
+  if (pos - (*off + sizeof (struct record_line)) > UINT16_MAX)
+  {
+    /* record data too long */
+    *off = start;
+    return GNUNET_NO;
+  }
+  rl.type = htons (record->type);
+  rl.class = htons (record->class);
+  rl.ttl = htonl (GNUNET_TIME_absolute_get_remaining (record->expiration_time).rel_value / 1000); /* in seconds */
+  rl.data_len = htons ((uint16_t) (pos - (*off + sizeof (struct record_line))));
+  memcpy (&dst[*off], &rl, sizeof (struct record_line));
+  *off = pos;
+  return GNUNET_OK;  
+}