uint8_t* dns_packet_append_name(struct dns_packet *p, const char *name)
{
uint8_t *d, *f = NULL;
assert(p);
for (;;) {
size_t n = strcspn(name, ".");
if (!n || n > 63)
return NULL;
d = dns_packet_extend(p, n+1);
if (!f)
f = d;
d[0] = (uint8_t)n;
memcpy(d+1, name, n);
name += n;
/* no trailing dot */
if (!*name)
break;
name ++;
/* trailing dot */
if (!*name)
break;
}
d = dns_packet_extend(p, 1);
d[0] = 0;
return f;
}
uint8_t* dns_packet_append_text(struct dns_packet *p, const char *text)
{
uint8_t *d, *f = NULL;
assert(p);
for (;;) {
size_t n = strcspn(text, "\n");
if (!n || n > 63)
return NULL;
d = dns_packet_extend(p, n+1);
if (!f)
f = d;
d[0] = (uint8_t)n;
memcpy(d+1, text, n);
text += n;
/* no trailing dot */
if (!*text)
break;
text ++;
/* trailing dot */
if (!*text)
break;
}
d = dns_packet_extend(p, 1);
d[0] = 0;
return f;
}
uint8_t* dns_packet_append_uint16(struct dns_packet *p, uint16_t v) {
uint8_t *d;
assert(p);
d = dns_packet_extend(p, sizeof(uint16_t));
SET_16_P(d, htons(v));
return d;
}
uint8_t *dns_packet_append_ipv6(struct dns_packet *p, struct ipv6_address_struct_t *v)
{
int n;
uint8_t *d;
assert(p);
d = dns_packet_extend(p, sizeof(v->address));
for(n=0; n<sizeof(v->address); n++)
d[n]=v->address[n];
return d;
}
uint8_t* dns_packet_append_uint32(struct dns_packet *p, uint32_t v)
{
uint8_t *d;
uint32_t u;
assert(p);
d = dns_packet_extend(p, sizeof(uint32_t));
u=htonl(v);
memcpy(d,&u,sizeof(u));
return d;
}
uint8_t *dns_packet_append_name_compressed(struct dns_packet *p, const char *name, uint8_t *prev) {
uint8_t *d;
signed long k;
assert(p);
if (!prev)
return dns_packet_append_name(p, name);
k = prev - p->data;
if (k < 0 || k >= 0x4000 || (size_t) k >= p->size)
return dns_packet_append_name(p, name);
d = dns_packet_extend(p, sizeof(uint16_t));
SET_16_P(d, htons((0xC000 | k)));
return prev;
}
uint8_t *dns_packet_append_name_compressed(struct dns_packet *p, const char *name, uint8_t *prev)
{
int8_t *d;
ptrdiff_t k;
uint16_t u;
assert(p);
if (!prev)
return dns_packet_append_name(p, name);
k = prev - p->data;
if (k < 0 || k >= 0x4000 || (size_t) k >= p->size)
return dns_packet_append_name(p, name);
d = dns_packet_extend(p, sizeof(uint16_t));
u=htons((0xC000 | (u_short)k));
memcpy(d,&u,sizeof(u));
return prev;
}
