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#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include "resolver.h"
#include "addr.h"
#include "binding.h"
#include "../io/log.h"
static bool lookup(
Question* question,
Packet* response,
BindingType type,
SocketAddr addr
) {
INIT_LOG_BUFFER(log)
LOGONLY(print_socket_addr(&addr, log);)
TRACE("Attempting lookup on fallback dns %s", log);
Connection request;
if (!create_request(type, &addr, &request)) {
return false;
}
Packet req;
memset(&req, 0, sizeof(Packet));
req.header.id = response->header.id;
req.header.opcode = response->header.opcode;
req.header.questions = 1;
req.header.recursion_desired = true;
req.questions = malloc(sizeof(Question));
req.questions[0] = *question;
if (!request_packet(&request, &req, response)) {
free_request(&request);
free(req.questions);
ERROR("Failed to request fallback dns: %s", strerror(errno));
return false;
}
free_request(&request);
free(req.questions);
return true;
}
static bool search(Question* question, Packet* result, BindingType type, const RecordMap* map) {
IpAddr addr;
uint8_t ip[4] = {1, 1, 1, 1};
create_ip_addr(ip, &addr);
uint16_t port = 53;
SocketAddr saddr;
create_socket_addr(port, addr, &saddr);
while(1) {
if (record_map_get(map, question, result)) {
TRACE("Found answer in user defined config");
return true;
}
if (!lookup(question, result, type, saddr)) {
return false;
}
if (result->header.answers > 0 && result->header.rescode == NOERROR) {
return true;
}
if (result->header.rescode == NXDOMAIN) {
return true;
}
if (get_resolved_ns(result, question->domain, &addr)) {
continue;
}
Question new_question;
if (!get_unresoled_ns(result, question->domain, &new_question)) {
return true;
}
Packet recurse;
if (!search(&new_question, &recurse, type, map)) {
return false;
}
free_question(&new_question);
IpAddr random;
if (!get_random_a(&recurse, &random)) {
free_packet(&recurse);
return true;
} else {
free_packet(&recurse);
addr = random;
}
}
}
static void push_records(Record* from, uint8_t from_len, Record** to, uint8_t to_len) {
if(from_len < 1) return;
*to = realloc(*to, sizeof(Record) * (from_len + to_len));
memcpy(*to + to_len, from, from_len * sizeof(Record));
}
static void push_questions(Question* from, uint8_t from_len, Question** to, uint8_t to_len) {
if(from_len < 1) return;
*to = realloc(*to, sizeof(Question) * (from_len + to_len));
memcpy(*to + to_len, from, from_len * sizeof(Question));
}
void handle_query(const Packet* request, Packet* response, BindingType type, const RecordMap* map) {
memset(response, 0, sizeof(Packet));
response->header.id = request->header.id;
response->header.opcode = request->header.opcode;
response->header.recursion_desired = true;
response->header.recursion_available = true;
response->header.response = true;
if (request->header.questions < 1) {
response->header.response = FORMERR;
return;
}
for (uint16_t i = 0; i < request->header.questions; i++) {
Packet result;
memset(&result, 0, sizeof(Packet));
result.header.id = response->header.id;
if (!search(&request->questions[i], &result, type, map)) {
response->header.response = SERVFAIL;
break;
}
push_questions(
result.questions,
result.header.questions,
&response->questions,
response->header.questions
);
response->header.questions += result.header.questions;
push_records(
result.answers,
result.header.answers,
&response->answers,
response->header.answers
);
response->header.answers += result.header.answers;
push_records(
result.authorities,
result.header.authoritative_entries,
&response->authorities,
response->header.authoritative_entries
);
response->header.authoritative_entries += result.header.authoritative_entries;
push_records(
result.resources,
result.header.resource_entries,
&response->resources,
response->header.resource_entries
);
response->header.resource_entries += result.header.resource_entries;
if (result.header.z == false) {
// Not from cache
free(result.questions);
free(result.answers);
free(result.authorities);
free(result.resources);
} else {
response->header.z = true;
}
}
}
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