static int str_label(
const knot_dname_t *zone,
char *buff,
size_t buff_len,
uint8_t right_index)
{
int labels = knot_dname_labels(zone, NULL);
// Check for root label of the root zone.
if (labels == 0 && right_index == 0) {
return str_zone(zone, buff, buff_len);
// Check for labels error or for an exceeded index.
} else if (labels < 1 || labels <= right_index) {
buff[0] = '\0';
return KNOT_EOK;
}
// ~ Label length + label + root label.
knot_dname_t label[1 + KNOT_DNAME_MAXLABELLEN + 1];
// Compute the index from the left.
assert(labels > right_index);
uint8_t index = labels - right_index - 1;
// Create a dname from the single label.
int prefix = (index > 0) ? knot_dname_prefixlen(zone, index, NULL) : 0;
uint8_t label_len = *(zone + prefix);
memcpy(label, zone + prefix, 1 + label_len);
label[1 + label_len] = '\0';
return str_zone(label, buff, buff_len);
}
/*----------------------------------------------------------------------------*/
_public_
knot_dname_t *knot_dname_replace_suffix(const knot_dname_t *name, unsigned labels,
const knot_dname_t *suffix)
{
if (name == NULL)
return NULL;
/* Calculate prefix and suffix lengths. */
int dname_lbs = knot_dname_labels(name, NULL);
assert(dname_lbs >= labels);
unsigned prefix_lbs = dname_lbs - labels;
/* Trim 1 octet from prefix, as it is measured as FQDN. */
int prefix_len = knot_dname_prefixlen(name, prefix_lbs, NULL) - 1;
int suffix_len = knot_dname_size(suffix);
if (prefix_len < 0 || suffix_len < 0)
return NULL;
/* Create target name. */
int new_len = prefix_len + suffix_len;
knot_dname_t *out = malloc(new_len);
if (out == NULL)
return NULL;
/* Copy prefix. */
uint8_t *dst = out;
while (prefix_lbs > 0) {
memcpy(dst, name, *name + 1);
dst += *name + 1;
name = knot_wire_next_label(name, NULL);
--prefix_lbs;
}
/* Copy suffix. */
while (*suffix != '\0') {
memcpy(dst, suffix, *suffix + 1);
dst += *suffix + 1;
suffix = knot_wire_next_label(suffix, NULL);
}
*dst = '\0';
return out;
}
/*----------------------------------------------------------------------------*/
_public_
int knot_dname_realsize(const knot_dname_t *name, const uint8_t *pkt)
{
return knot_dname_prefixlen(name, KNOT_DNAME_MAXLABELS, pkt);
}