private Task <DnsResponse> StartResolve(DnsRequestType type, string strName, out bool newTask)
{
if (dnsProvider == null)
{
throw new Exception("no dns resolver");
}
lock (resolvingNames) {
newTask = false;
if (resolvingNames.TryGetValue(strName, out var rt))
{
// try to return a running task
if (type == DnsRequestType.A && rt.A != null)
{
return(rt.A);
}
if (type == DnsRequestType.AAAA || rt.AAAA != null)
{
return(rt.AAAA);
}
if (type == DnsRequestType.AnAAAA)
{
if (rt.A == rt.AAAA)
{
return(rt.A);
}
if (rt.A != null && rt.AAAA != null)
{
return(UnionWarpper(rt));
}
}
}
else
{
rt = new ResolveTask();
resolvingNames[strName] = rt;
}
var task = Controller.ResolveName(this, AdapterRef.FromAdapter(dnsProvider), new DnsRequest(strName, type));
if ((type & DnsRequestType.A) != 0 && rt.A == null)
{
rt.A = task;
}
if ((type & DnsRequestType.AAAA) != 0 && rt.AAAA == null)
{
rt.AAAA = task;
}
newTask = true;
return(task);
}
}
private async Task <IResponse> HandleDnsRequest(IRequest request)
{
var q = request;
var r = Response.FromRequest(request);
r.ResponseCode = ResponseCode.ServerFailure;
try {
var questions = q.Questions;
if (questions.Count == 0)
{
Logger.warning($"id {q.Id} does not contain any questions." +
$"\nAdditionalRecords: {string.Join(", ", q.AdditionalRecords)}");
}
//
var queryNames = new Dictionary <Domain, DnsRequestType>();
foreach (var item in questions)
{
if (item.Type == RecordType.A || item.Type == RecordType.AAAA)
{
DnsRequestType type = item.Type == RecordType.A ? DnsRequestType.A : DnsRequestType.AAAA;
if (verbose)
{
Logger.debugForce($"id {q.Id} query: {item}");
}
if (!queryNames.ContainsKey(item.Name))
{
queryNames.Add(item.Name, type);
}
else
{
queryNames[item.Name] |= type;
}
}
else if (item.Type == RecordType.PTR)
{
}
else
{
Logger.warning("Unsupported DNS record: " + item);
}
}
foreach (var kv in queryNames)
{
DnsRequestType reqType = kv.Value;
bool reqv4 = (reqType & DnsRequestType.A) != 0;
bool reqv6 = (reqType & DnsRequestType.AAAA) != 0;
var strName = kv.Key.ToString();
IEnumerable <IPAddress> ips = emptyIps;
IpRecord val = new IpRecord();
bool exist = cacheDns?.QueryByName(strName, out val) ?? false;
var now = DateTime.Now;
if (val.expire < now)
{
val.ipLongs = null;
}
if (val.expire6 < now)
{
val.ips6 = null;
}
var ipLongs = val.ipLongs;
var ips6 = val.ips6;
if (!exist || (reqv4 && ipLongs == null) || (reqv6 && ips6 == null))
{
var startTime = Logging.getRuntime();
var task = StartResolve(reqType, strName, out var newTask);
try {
try {
var resp = await task;
if (resp != null)
{
var iparr = resp.Addresses;
ips = iparr;
ipFilter(iparr, ref ipLongs, ref ips6);
}
} catch (Exception e) {
if (newTask)
{
Logger.warning("resolving: " + strName + " (" + reqType + "): " + e.Message + " (" + (Logging.getRuntime() - startTime) + " ms)");
}
continue;
}
if (newTask)
{
Logger.info("" + strName + " (" + reqType + ") -> " + string.Join("|", ips)
+ " (" + (Logging.getRuntime() - startTime) + " ms)");
var newExpire = DateTime.Now.AddSeconds(cache_ttl);
// If we requested only A records (not AnAAAA) and an empty result returned, then there's
// really no A records, so we can cache the empty result:
if (reqType == DnsRequestType.A && ipLongs == null)
{
ipLongs = new uint[0];
}
if (ipLongs != null)
{
val.ipLongs = ipLongs;
val.expire = newExpire;
}
// The same reason:
if (reqType == DnsRequestType.AAAA && ips6 == null)
{
ips6 = new Ip6[0];
}
if (ips6 != null)
{
val.ips6 = ips6;
val.expire6 = newExpire;
}
cacheDns?.Set(strName, ref val);
}
} finally {
if (newTask)
{
EndResolve(strName, task);
}
}
}
if (reqv4 && ipLongs != null)
{
foreach (var item in ipLongs)
{
r.AnswerRecords.Add(new ResourceRecord(kv.Key, BitConverter.GetBytes(item), RecordType.A, ttl: TimeSpan.FromSeconds(ttl)));
}
}
if (reqv6 && ips6 != null)
{
foreach (var item in ips6)
{
r.AnswerRecords.Add(new ResourceRecord(kv.Key, item.ToBytes(), RecordType.AAAA, ttl: TimeSpan.FromSeconds(ttl)));
}
}
r.ResponseCode = ResponseCode.NoError;
}
} catch (Exception e) {
Logger.exception(e, Logging.Level.Error, "server");
}
return(r);
}
public DnsRequest(string name, DnsRequestType type)
{
Name = name;
Type = type;
}
