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#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;
}
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