header_t *
dns_header_decode(netif_t *netif, packet_t *packet, raw_packet_t *raw_packet, packet_offset_t offset)
{
dns_header_t *dns = dns_header_new();
packet_offset_t field_offset;
if (raw_packet->len < (offset + DNS_HEADER_LEN)) {
LOG_PRINTLN(LOG_HEADER_DNS, LOG_ERROR, ("decode DNS header: size too small (present=%u, required=%u)", raw_packet->len - offset, DNS_HEADER_LEN));
DNS_FAILURE_EXIT;
}
/* fetch header */
uint8_to_uint16(&(dns->id), &(raw_packet->data[offset + DNS_HEADER_OFFSET_ID]));
uint8_to_uint16(&(dns->flags.raw), &(raw_packet->data[offset + DNS_HEADER_OFFSET_FLAGS]));
uint8_to_uint16(&(dns->qd_count), &(raw_packet->data[offset + DNS_HEADER_OFFSET_QD_COUNT]));
uint8_to_uint16(&(dns->an_count), &(raw_packet->data[offset + DNS_HEADER_OFFSET_AN_COUNT]));
uint8_to_uint16(&(dns->ns_count), &(raw_packet->data[offset + DNS_HEADER_OFFSET_NS_COUNT]));
uint8_to_uint16(&(dns->ar_count), &(raw_packet->data[offset + DNS_HEADER_OFFSET_AR_COUNT]));
field_offset = offset + DNS_HEADER_LEN;
/* question section */
if (dns->qd_count > 0) {
dns->qd = dns_query_new();
if (!dns_header_decode_query(raw_packet, offset, &field_offset, dns->qd_count, dns->qd)) {
dns_query_free(dns->qd);
DNS_FAILURE_EXIT;
}
}
/* answer records section */
if (dns->an_count > 0) {
dns->an = dns_rr_new();
if (!dns_header_decode_rr(raw_packet, offset, &field_offset, dns->an_count, dns->an)) {
dns_rr_free(dns->an);
DNS_FAILURE_EXIT;
}
}
/* authority records section */
if (dns->ns_count > 0) {
dns->ns = dns_rr_new();
if (!dns_header_decode_rr(raw_packet, offset, &field_offset, dns->ns_count, dns->ns)) {
dns_rr_free(dns->ns);
DNS_FAILURE_EXIT;
}
}
/* additional records section */
if (dns->ar_count > 0) {
dns->ar = dns_rr_new();
if (!dns_header_decode_rr(raw_packet, offset, &field_offset, dns->ar_count, dns->ar)) {
dns_rr_free(dns->ar);
DNS_FAILURE_EXIT;
}
}
return (header_t *) dns;
}
static bool
dns_header_decode_query(raw_packet_t *raw_packet, packet_offset_t header_offset, packet_offset_t *field_offset, uint16_t count, dns_query_t *query)
{
dns_label_t *label;
for (; count > 0; count--) {
if (raw_packet->len < (*field_offset + DNS_QUERY_MIN_LEN)) {
LOG_PRINTLN(LOG_HEADER_DNS, LOG_ERROR, ("decode DNS query: size too small (present=%" PRIoffset ", required=%" PRIoffset ", offset=%" PRIoffset "/%x)", raw_packet->len - *field_offset, DNS_QUERY_MIN_LEN, *field_offset, *field_offset));
return false;
}
/* qname */
label = dns_label_new();
if (!dns_header_decode_label(raw_packet, header_offset, field_offset, label)) {
dns_label_free(label);
return false;
}
query->qname = label;
/* qtype + qclass */
uint8_to_uint16(&(query->qtype), &(raw_packet->data[*field_offset + DNS_QUERY_OFFSET_QTYPE]));
uint8_to_uint16(&(query->qclass), &(raw_packet->data[*field_offset + DNS_QUERY_OFFSET_QCLASS]));
*field_offset += DNS_QUERY_SIZE;
/* not the last query */
if (count > 1) {
query->next = dns_query_new();
query = query->next;
}
}
return true;
}
static int bus_method_resolve_address(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
_cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
_cleanup_free_ char *reverse = NULL;
Manager *m = userdata;
int family, ifindex;
uint64_t flags;
const void *d;
DnsQuery *q;
size_t sz;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "ii", &ifindex, &family);
if (r < 0)
return r;
if (!IN_SET(family, AF_INET, AF_INET6))
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Unknown address family %i", family);
r = sd_bus_message_read_array(message, 'y', &d, &sz);
if (r < 0)
return r;
if (sz != FAMILY_ADDRESS_SIZE(family))
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid address size");
r = sd_bus_message_read(message, "t", &flags);
if (r < 0)
return r;
r = check_ifindex_flags(ifindex, &flags, error);
if (r < 0)
return r;
r = dns_name_reverse(family, d, &reverse);
if (r < 0)
return r;
question = dns_question_new(1);
if (!question)
return -ENOMEM;
key = dns_resource_key_new_consume(DNS_CLASS_IN, DNS_TYPE_PTR, reverse);
if (!key)
return -ENOMEM;
reverse = NULL;
r = dns_question_add(question, key);
if (r < 0)
return r;
r = dns_query_new(m, &q, question, ifindex, flags);
if (r < 0)
return r;
q->request = sd_bus_message_ref(message);
q->request_family = family;
memcpy(&q->request_address, d, sz);
q->complete = bus_method_resolve_address_complete;
r = dns_query_bus_track(q, bus, message);
if (r < 0)
return r;
r = dns_query_go(q);
if (r < 0) {
dns_query_free(q);
if (r == -ESRCH)
sd_bus_error_setf(error, BUS_ERROR_NO_NAME_SERVERS, "No appropriate name servers or networks for name found");
return r;
}
return 1;
}
static int bus_method_resolve_hostname(sd_bus *bus, sd_bus_message *message, void *userdata, sd_bus_error *error) {
_cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
Manager *m = userdata;
const char *hostname;
int family, ifindex;
uint64_t flags;
DnsQuery *q;
int r;
assert(bus);
assert(message);
assert(m);
r = sd_bus_message_read(message, "isit", &ifindex, &hostname, &family, &flags);
if (r < 0)
return r;
if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Unknown address family %i", family);
r = dns_name_normalize(hostname, NULL);
if (r < 0)
return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid hostname '%s'", hostname);
r = check_ifindex_flags(ifindex, &flags, error);
if (r < 0)
return r;
question = dns_question_new(family == AF_UNSPEC ? 2 : 1);
if (!question)
return -ENOMEM;
if (family != AF_INET6) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A, hostname);
if (!key)
return -ENOMEM;
r = dns_question_add(question, key);
if (r < 0)
return r;
}
if (family != AF_INET) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_AAAA, hostname);
if (!key)
return -ENOMEM;
r = dns_question_add(question, key);
if (r < 0)
return r;
}
r = dns_query_new(m, &q, question, ifindex, flags);
if (r < 0)
return r;
q->request = sd_bus_message_ref(message);
q->request_family = family;
q->request_hostname = hostname;
q->complete = bus_method_resolve_hostname_complete;
r = dns_query_bus_track(q, bus, message);
if (r < 0)
return r;
r = dns_query_go(q);
if (r < 0) {
dns_query_free(q);
if (r == -ESRCH)
sd_bus_error_setf(error, BUS_ERROR_NO_NAME_SERVERS, "No appropriate name servers or networks for name found");
return r;
}
return 1;
}
