static void register_send(settings_t *settings)
{
dns_t *dns;
uint8_t *packet;
uint32_t packet_length;
/* Create the DNS object. */
dns = dns_create();
dns->flags = FLAGS_R_REQUEST | FLAGS_NM_RD | FLAGS_NM_B;
if(settings->query_type == TYPE_REGISTER)
dns->flags = FLAGS_OPCODE_NAME_REGISTRATION;
else if(settings->query_type == TYPE_REFRESH)
dns->flags = FLAGS_OPCODE_NAME_REFRESH;
else if(settings->query_type == TYPE_RELEASE)
dns->flags = FLAGS_OPCODE_NAME_RELEASE;
else
fprintf(stderr, "Unknown query type made it into register_send() -- %d\n", settings->query_type);
dns->trn_id = 0x1337;
/* Add the question/additional. */
dns_add_netbios_question(dns, settings->name, settings->name_type, NULL, DNS_TYPE_NB, 0x0001);
dns_add_additional_NB(dns, settings->name, settings->name_type, NULL, 0x0001, 0, 0x0000, settings->source);
/* Convert the DNS object to a packet. */
packet = dns_to_packet(dns, &packet_length);
dns_destroy(dns);
/* Put it on the wire. */
fprintf(stderr, "Sending query.\n");
udp_send(settings->socket, settings->target, settings->port, packet, packet_length);
safe_free(packet);
}
static void send_poison_response(settings_t *settings, int socket, char *addr, uint16_t port, char *name, uint8_t name_type, uint16_t trn_id)
{
dns_t *response = dns_create();
uint8_t *packet;
uint32_t packet_length;
fprintf(stderr, "Replying to request for '%s<%02x>' with %s\n", name, name_type, settings->source);
response->trn_id = trn_id;
response->flags = FLAGS_R_RESPONSE | FLAGS_OPCODE_QUERY | FLAGS_NM_AA | FLAGS_NM_RD;
dns_add_answer_NB(response, name, name_type, NULL, 1, 0, 0x0000, settings->source);
packet = dns_to_packet(response, &packet_length);
dns_destroy(response);
udp_send(socket, addr, port, packet, packet_length);
safe_free(packet);
}
static void send_conflict_response(settings_t *settings, int socket, char *addr, uint16_t port, char *name, uint8_t name_type, uint16_t trn_id)
{
dns_t *response = dns_create();
uint8_t *packet;
uint32_t packet_length;
fprintf(stderr, "Replying to registration request for '%s<%02x>' with a conflict (%s)\n", name, name_type, settings->source);
response->trn_id = trn_id;
response->flags = FLAGS_R_RESPONSE | FLAGS_OPCODE_NAME_REGISTRATION | FLAGS_NM_AA | FLAGS_NM_RD | FLAGS_NM_RA | FLAGS_RCODE_ACT_ERR;
dns_add_answer_NB(response, name, name_type, NULL, 1, 0, 0x0000, settings->source ? settings->source : "0.0.0.0");
packet = dns_to_packet(response, &packet_length);
dns_destroy(response);
udp_send(socket, addr, port, packet, packet_length);
safe_free(packet);
}
static void query_send(settings_t *settings)
{
dns_t *dns;
uint8_t *packet;
uint32_t packet_length;
/* Create the DNS object. */
dns = dns_create();
dns->flags = FLAGS_R_REQUEST | FLAGS_OPCODE_QUERY | FLAGS_NM_B;
dns->trn_id = 0x1337;
/* Add the question. */
dns_add_netbios_question(dns, settings->name, settings->name_type, NULL, settings->query_type == TYPE_QUERY_NB ? DNS_TYPE_NB : DNS_TYPE_NBSTAT, 0x0001);
/* Convert the DNS object to a packet. */
packet = dns_to_packet(dns, &packet_length);
dns_destroy(dns);
/* Put it on the wire. */
fprintf(stderr, "Sending query.\n");
udp_send(settings->socket, settings->target, settings->port, packet, packet_length);
safe_free(packet);
}
static SELECT_RESPONSE_t dns_callback(void *group, int socket, uint8_t *packet, size_t packet_length, char *addr, uint16_t port, void *s)
{
settings_t *settings = (settings_t*) s;
dns_t *response;
uint8_t *response_packet;
uint32_t response_packet_length;
/* Parse the DNS packet. */
dns_t *request = dns_create_from_packet(packet, packet_length);
/* Create the response packet. */
response = dns_create();
response->trn_id = request->trn_id;
response->flags = 0x8000;
if(request->question_count > 0)
{
int i;
/* Display the questions. */
for(i = 0; i < request->question_count; i++)
{
/* Grab the question and display it. */
question_t this_question = request->questions[i];
fprintf(stderr, "Question %d: %s (0x%04x 0x%04x)\n", i, this_question.name, this_question.type, this_question.class);
/* Add an answer, if appropriate. */
dns_add_question(response, this_question.name, this_question.type, this_question.class);
if(settings->A && (this_question.type == DNS_TYPE_A || this_question.type == DNS_TYPE_ANY))
{
fprintf(stderr, "(Responding with %s)\n", settings->A);
dns_add_answer_A(response, this_question.name, 0x0001, settings->TTL, settings->A);
}
#ifndef WIN32
else if(settings->AAAA && this_question.type == DNS_TYPE_AAAA)
{
fprintf(stderr, "(Responding with %s)\n", settings->AAAA);
dns_add_answer_AAAA(response, this_question.name, 0x0001, settings->TTL, settings->AAAA);
}
#endif
}
/* If we have any answers, send back our packet. */
if(response->answer_count > 0)
{
/* Send the packet. */
response_packet = dns_to_packet(response, &response_packet_length);
udp_send(socket, addr, port, response_packet, response_packet_length);
}
else
{
/* Send back an error. */
response_packet = dns_create_error_string(request->trn_id, request->questions[0], &response_packet_length);
udp_send(socket, addr, port, response_packet, response_packet_length);
}
/* Delete the response. */
safe_free(response_packet);
dns_destroy(response);
/* Delete the request. */
dns_destroy(request);
}
static grpc_resolver *dns_factory_create_resolver(
grpc_resolver_factory *factory, grpc_uri *uri,
grpc_subchannel_factory *subchannel_factory) {
return dns_create(uri, "https", grpc_create_pick_first_lb_policy,
subchannel_factory);
}
/* 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);
}
static grpc_resolver *dns_factory_create_resolver(
grpc_resolver_factory *factory, grpc_resolver_args *args) {
return dns_create(args, "https", "pick_first");
}
int main (int argc, char **argv)
{
int opt;
enum log_level log_level = LOG_LEVEL;
int err = 0;
struct event_main *event_main;
struct options options = {
.resolver = "localhost",
};
while ((opt = getopt_long(argc, argv, "hqvdR:", long_options, NULL)) >= 0) {
switch (opt) {
case 'h':
help(argv[0]);
return 0;
case 'q':
log_level = LOG_ERROR;
break;
case 'v':
log_level = LOG_INFO;
break;
case 'd':
log_level = LOG_DEBUG;
break;
case 'R':
options.resolver = optarg;
break;
default:
help(argv[0]);
return 1;
}
}
// apply
log_set_level(log_level);
if ((err = event_main_create(&event_main))) {
log_fatal("event_main_create");
goto error;
}
if ((err = dns_create(event_main, &options.dns, options.resolver))) {
log_fatal("dns_create: %s", options.resolver);
goto error;
}
while (optind < argc && !err) {
struct dns_task task = {
.options = &options,
.arg = argv[optind++],
};
// start async task
if ((err = event_start(event_main, dns, &task))) {
log_fatal("event_start: %s", task.arg);
}
}
// mainloop
if ((err = event_main_run(event_main))) {
log_fatal("event_main");
}
error:
if (options.dns)
dns_destroy(options.dns);
return err;
}
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);
}
static grpc_resolver *dns_factory_create_resolver(
grpc_exec_ctx *exec_ctx, grpc_resolver_factory *factory,
grpc_resolver_args *args) {
return dns_create(exec_ctx, args, "https");
}
