static int pico_dns_client_user_callback(struct pico_dns_answer_suffix *asuffix, struct pico_dns_query *q)
{
uint32_t ip = 0;
char *str = NULL;
char *rdata = (char *) asuffix + sizeof(struct pico_dns_answer_suffix);
switch (q->qtype)
{
case PICO_DNS_TYPE_A:
ip = long_from(rdata);
str = PICO_ZALLOC(PICO_DNS_IPV4_ADDR_LEN);
pico_ipv4_to_string(str, ip);
break;
#ifdef PICO_SUPPORT_IPV6
case PICO_DNS_TYPE_AAAA:
{
struct pico_ip6 ip6;
memcpy(&ip6.addr, rdata, sizeof(struct pico_ip6));
str = PICO_ZALLOC(PICO_DNS_IPV6_ADDR_LEN);
pico_ipv6_to_string(str, ip6.addr);
break;
}
#endif
case PICO_DNS_TYPE_PTR:
pico_dns_client_answer_domain(rdata);
str = PICO_ZALLOC((size_t)(asuffix->rdlength - PICO_DNS_LABEL_INITIAL));
if (!str) {
pico_err = PICO_ERR_ENOMEM;
return -1;
}
memcpy(str, rdata + PICO_DNS_LABEL_INITIAL, short_be(asuffix->rdlength) - PICO_DNS_LABEL_INITIAL);
break;
default:
dns_dbg("DNS ERROR: incorrect qtype (%u)\n", q->qtype);
break;
}
if (q->retrans) {
q->callback(str, q->arg);
q->retrans = 0;
PICO_FREE(str);
pico_dns_client_del_query(q->id);
}
return 0;
}
int pico_string_to_ipv4(const char *ipstr, uint32_t *ip)
{
unsigned char buf[PICO_SIZE_IP4] = {
0
};
int cnt = 0;
char p;
if (pico_string_check_null_args(ipstr, ip) < 0)
return -1;
while((p = *ipstr++) != 0 && cnt < PICO_SIZE_IP4)
{
if (pico_is_digit(p)) {
buf[cnt] = (uint8_t)((10 * buf[cnt]) + (p - '0'));
} else if (p == '.') {
cnt++;
} else {
return -1;
}
}
/* Handle short notation */
if (cnt == 1) {
buf[3] = buf[1];
buf[1] = 0;
buf[2] = 0;
} else if (cnt == 2) {
buf[3] = buf[2];
buf[2] = 0;
} else if (cnt != 3) {
/* String could not be parsed, return error */
return -1;
}
*ip = long_from(buf);
return 0;
}
static void pico_dns_client_callback(uint16_t ev, struct pico_socket *s)
{
char *q_qname, *q_suf, *a_hdr, *a_qname, *a_suf, *a_rdata;
struct dns_message_hdr *hdr;
struct dns_query_suffix query_suf;
struct dns_answer_suffix answer_suf;
struct pico_dns_key test, *key;
char *answer;
char dns_answer[PICO_DNS_MAX_RESPONSE_LEN] = {0};
uint8_t valid_suffix = 0;
uint16_t compression = 0;
int i = 0, r = 0;
if (ev & PICO_SOCK_EV_RD) {
r = pico_socket_read(s, dns_answer, PICO_DNS_MAX_RESPONSE_LEN);
pico_socket_close(s);
if (r == PICO_DNS_MAX_RESPONSE_LEN || r < (int)sizeof(struct dns_message_hdr)) {
dns_dbg("DNS ERROR: received incorrect number(%d) of bytes\n", r);
return;
}
/* Check header validity */
a_hdr = dns_answer;
hdr = (struct dns_message_hdr *) a_hdr;
pico_dns_client_hdr_ntoh(hdr);
if (GET_FLAG_QR(hdr) != PICO_DNS_QR_RESPONSE || GET_FLAG_OPCODE(hdr) != PICO_DNS_OPCODE_QUERY
|| GET_FLAG_TC(hdr) == PICO_DNS_TC_IS_TRUNCATED || GET_FLAG_RCODE(hdr) != PICO_DNS_RCODE_NO_ERROR) {
dns_dbg("DNS ERROR: OPCODE %d | TC %d | RCODE %d\n", GET_FLAG_OPCODE(hdr), GET_FLAG_TC(hdr), GET_FLAG_RCODE(hdr));
return;
}
if (hdr->ancount < 1 || r < (int)(sizeof(struct dns_message_hdr) + hdr->qdcount * sizeof(struct dns_query_suffix)
+ hdr->ancount * sizeof(struct dns_answer_suffix))) {
dns_dbg("DNS ERROR: ancount < 1 OR received number(%d) of bytes too low\n", r);
return;
}
/* Find DNS key */
test.id = hdr->id;
key = pico_tree_findKey(&DNSTable,&test);
if (!key) {
dns_dbg("DNS WARNING: key with id %u not found\n", hdr->id);
return;
}
key->retrans = 0;
/* Check query suffix validity */
q_qname = a_hdr + sizeof(struct dns_message_hdr);
q_suf = pico_dns_client_seek(q_qname);
query_suf = *(struct dns_query_suffix *) q_suf;
if (short_be(query_suf.qtype) != key->qtype || short_be(query_suf.qclass) != key->qclass) {
dns_dbg("DNS ERROR: received qtype (%u) or qclass (%u) incorrect\n", short_be(query_suf.qtype), short_be(query_suf.qclass));
return;
}
/* Seek answer suffix */
a_qname = q_suf + sizeof(struct dns_query_suffix);
a_suf = a_qname;
while(i++ < hdr->ancount) {
uint16_t comp_h = short_from(a_suf);
compression = short_be(comp_h);
switch (compression >> 14)
{
case PICO_DNS_POINTER:
while (compression >> 14 == PICO_DNS_POINTER) {
dns_dbg("DNS: pointer\n");
a_suf += sizeof(uint16_t);
comp_h = short_from(a_suf);
compression = short_be(comp_h);
}
break;
case PICO_DNS_LABEL:
dns_dbg("DNS: label\n");
a_suf = pico_dns_client_seek(a_qname);
break;
default:
dns_dbg("DNS ERROR: incorrect compression (%u) value\n", compression);
return;
}
/* Check answer suffix validity */
answer_suf = *(struct dns_answer_suffix *)a_suf;
if (short_be(answer_suf.qtype) != key->qtype || short_be(answer_suf.qclass) != key->qclass) {
dns_dbg("DNS WARNING: received qtype (%u) or qclass (%u) incorrect\n", short_be(answer_suf.qtype), short_be(answer_suf.qclass));
a_suf = a_suf + sizeof(struct dns_answer_suffix) + short_be(answer_suf.rdlength);
continue;
}
if (short_be(answer_suf.ttl) > PICO_DNS_MAX_TTL) {
dns_dbg("DNS WARNING: received TTL (%u) > MAX (%u)\n", short_be(answer_suf.ttl), PICO_DNS_MAX_TTL);
a_suf = a_suf + sizeof(struct dns_answer_suffix) + short_be(answer_suf.rdlength);
continue;
}
valid_suffix = 1;
break;
}
if (!valid_suffix) {
dns_dbg("DNS ERROR: invalid dns answer suffix\n");
return;
}
a_rdata = a_suf + sizeof(struct dns_answer_suffix);
if (key->qtype == PICO_DNS_TYPE_A) {
uint32_t ip_h = long_from(a_rdata);
dns_dbg("DNS: length %u | ip %08X\n", short_be(answer_suf.rdlength), long_be(ip_h));
answer = pico_zalloc(16);
pico_ipv4_to_string(answer, ip_h);
key->callback(answer, key->arg);
} else if (key->qtype == PICO_DNS_TYPE_PTR) {
pico_dns_client_reverse_label((char *) a_rdata);
dns_dbg("DNS: length %u | name %s\n", short_be(answer_suf.rdlength), (char *)a_rdata + 1);
answer = pico_zalloc(answer_suf.rdlength - 1);
memcpy(answer, (char *)a_rdata + 1, short_be(answer_suf.rdlength) - 1);
key->callback(answer, key->arg);
} else {
dns_dbg("DNS ERROR: incorrect qtype (%u)\n", key->qtype);
return;
}
}
