/* This function expects to receive the proper length of data. */
static void handle_packet_out(driver_dns_t *driver, uint8_t *data, size_t length)
{
size_t i;
dns_t *dns;
buffer_t *buffer;
uint8_t *encoded_bytes;
size_t encoded_length;
uint8_t *dns_bytes;
size_t dns_length;
size_t section_length;
assert(driver->s != -1); /* Make sure we have a valid socket. */
assert(data); /* Make sure they aren't trying to send NULL. */
assert(length > 0); /* Make sure they aren't trying to send 0 bytes. */
assert(length <= MAX_DNSCAT_LENGTH(driver->domain));
buffer = buffer_create(BO_BIG_ENDIAN);
/* If no domain is set, add the wildcard prefix at the start. */
if(!driver->domain)
{
buffer_add_bytes(buffer, (uint8_t*)WILDCARD_PREFIX, strlen(WILDCARD_PREFIX));
buffer_add_int8(buffer, '.');
}
section_length = 0;
/* TODO: I don't much care for this loop... */
for(i = 0; i < length; i++)
{
char hex_buf[3];
#ifdef WIN32
sprintf_s(hex_buf, 3, "%02x", data[i]);
#else
sprintf(hex_buf, "%02x", data[i]);
#endif
buffer_add_bytes(buffer, hex_buf, 2);
/* Add periods when we need them. */
section_length += 2;
if(i + 1 != length && section_length + 2 >= MAX_FIELD_LENGTH)
{
section_length = 0;
buffer_add_int8(buffer, '.');
}
}
/* If a domain is set, instead of the wildcard prefix, add the domain to the end. */
if(driver->domain)
{
buffer_add_int8(buffer, '.');
buffer_add_bytes(buffer, driver->domain, strlen(driver->domain));
}
buffer_add_int8(buffer, '\0');
/* Get the result out. */
encoded_bytes = buffer_create_string_and_destroy(buffer, &encoded_length);
/* Double-check we didn't mess up the length. */
assert(encoded_length <= MAX_DNS_LENGTH);
dns = dns_create(_DNS_OPCODE_QUERY, _DNS_FLAG_RD, _DNS_RCODE_SUCCESS);
dns_add_question(dns, (char*)encoded_bytes, driver->type, _DNS_CLASS_IN);
dns_bytes = dns_to_packet(dns, &dns_length);
LOG_INFO("Sending DNS query for: %s to %s:%d", encoded_bytes, driver->dns_host, driver->dns_port);
udp_send(driver->s, driver->dns_host, driver->dns_port, dns_bytes, dns_length);
safe_free(dns_bytes);
safe_free(encoded_bytes);
dns_destroy(dns);
}
int main(int argc, char *argv[])
{
dnsPacket *dns, *dnsresponse;
int iResult, iReceived;
char *qdomain, *qserver, *response;
unsigned short qtype = 1, qclass = 1;
qdomain = ((qdomain = command_arg_get(0, '-', argc, argv)) != NULL) ? qdomain : DNS_DEFAULT_LOOKUP;
qserver = ((qserver = command_arg_get(1, '-', argc, argv)) != NULL) ? qserver : DNS_LOOKUP_SERVER;
// create our empty DNS packet
dns = dns_create();
// set the required header fields
dns->base->id = DNS_IDENTIFIER;
// use recursive query?
if (command_opt_set("-r", argc, argv))
{
dns->base->flags |= DNS_FLAGS_RD;
printf("+ Using recursive querying\n");
}
// use a different query type?
if (command_opt_set("-cname", argc, argv))
{
qtype = DNS_TYPE_CNAME;
printf("+ Using CNAME query type\n");
}
else if (command_opt_set("-ns", argc, argv))
{
qtype = DNS_TYPE_NS;
printf("+ Using NS query type\n");
}
else if (command_opt_set("-mx", argc, argv))
{
qtype = DNS_TYPE_MX;
printf("+ Using MX query type\n");
}
else if (command_opt_set("-ptr", argc, argv))
{
qtype = DNS_TYPE_PTR;
printf("+ Using PTR query type\n");
}
else if (command_opt_set("-aaaa", argc, argv))
{
qtype = DNS_TYPE_AAAA;
printf("+ Using AAAA query type\n");
}
// add our question section
dns_add_question(dns, qdomain, strlen(qdomain), qtype, qclass);
dns_hton(dns);
// initialize the network
network_init(qserver, DNS_PORT);
network_connect_udp();
// send the packet out
printf("Looking up %s using %s...\n", qdomain, qserver);
iResult = network_send((char *)dns->base, dns->size);
assert(iResult > 0);
// block until a response is ready
response = network_receive(&iReceived);
assert(iReceived > 0);
// load up the response packet
dnsresponse = dns_parse(response, iReceived);
assert(dnsresponse->base->flags & DNS_FLAGS_RESPONSE && dnsresponse->base->id == DNS_IDENTIFIER);
output_print_response(dnsresponse);
output_print_sections(dnsresponse);
}
