/** Calls a callback function once for each option returned by a DHCP server.
*
* @param[in] data - The DHCP response data buffer to parse.
* @param[in] datasz - The length of @p data.
* @param[in] dhcpInfoCB - The callback function to call for each option.
* @param[in] context - Callback context data.
*
* @return Zero on success; non-zero on failure, with errno set to
* ENOTCONN (error during read), ETIMEDOUT (read timed out),
* ENOMEM (out of memory error), or EINVAL (parse error).
*
* @internal
*/
static int dhcpProcessOptions(unsigned char * data, size_t datasz,
DHCPInfoCallBack * dhcpInfoCB, void * context)
{
int err, taglen;
unsigned char tag;
/* validate vendor data header */
if (datasz < 4
|| *data++ != DHCP_COOKIE1 || *data++ != DHCP_COOKIE2
|| *data++ != DHCP_COOKIE3 || *data++ != DHCP_COOKIE4)
return -1; /* invalid dhcp response */
datasz -= 4; /* account for DHCP cookie values */
/* validate and process each tag in the vendor data */
while (datasz-- > 0 && (tag = *data++) != TAG_END)
{
if (tag != TAG_PAD)
{
if (!datasz-- || (taglen = *data++) > (int)datasz)
return -1; /* tag length greater than total data length */
if ((err = dhcpInfoCB(tag, data, taglen, context)) != 0)
return err;
datasz -= taglen;
data += taglen;
}
}
return 0;
}
/*=========================================================================*/
static int dhcpProcessOptions(unsigned char *data, size_t datasz,
DHCPInfoCallBack *dhcpInfoCB, void *context)
/* Calls dhcpInfoCB once for each option returned by the dhcp server.
Returns - zero on success, non-zero on failure
errno ENOTCONN error during read
ETIME read timed out
ENOMEM out of memory
EINVAL parse error
=========================================================================*/
{
int err, taglen;
unsigned char tag;
/* validate vendor data header */
if(datasz < 4
|| *data++ != DHCP_COOKIE1 || *data++ != DHCP_COOKIE2
|| *data++ != DHCP_COOKIE3 || *data++ != DHCP_COOKIE4)
return -1; /* invalid dhcp response */
datasz -= 4; /* account for DHCP cookie values */
/* validate and process each tag in the vendor data */
while(datasz-- > 0 && (tag = *data++) != TAG_END)
{
if(tag != TAG_PAD)
{
if(!datasz-- || (taglen = *data++) > (int)datasz)
return -1; /* tag length greater than total data length */
if((err = dhcpInfoCB(tag, data, taglen, context)))
return err;
datasz -= taglen;
data += taglen;
}
}
return 0;
}
