//// private sub-iterator
//private ResolutionIterator(ResolutionIterator iterator, DnsDomain domain, DnsClient.DNS.QTYPE question)
// : base(new Resolver(iterator.Resolver, domain), question, iterator.AddressCache)
//{
// IsSubIterator = true;
//}
#endregion
#region override
public override void Reset()
{
base.Reset();
LastAddressResult = null;
AddressIterator = null;
CNameIterator = null;
//TCRepeating = false;
RootCacheState = true;
}
public override void Reset()
{
base.Reset();
LastAddressResult = null;
AddressIterator = null;
CNameIterator = null;
//TCRepeating = false;
RootCacheState = true;
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
try
{
if (AddressIterator != null)
{
((IDisposable)AddressIterator).Dispose();
}
if (CNameIterator != null)
{
((IDisposable)CNameIterator).Dispose();
}
}
finally
{
AddressIterator = null;
CNameIterator = null;
}
}
base.Dispose(disposing);
}
protected override Results.ResolutionResult GetNextResult(out bool isCompleted, NameServer selected)
{
// Iteration may be delegated to CNameIterator if the requested name
// has been identified as alias.
if (!object.ReferenceEquals(null, CNameIterator))
{
CNameIterator.EnsureConnection(Resolver.Client);
return(CNameIterator.GetNextResult(out isCompleted, selected));
}
// A subsequent iteration may be running if a name server address needs to be resolved.
if (!object.ReferenceEquals(null, AddressIterator))
{
AddressIterator.EnsureConnection(Resolver.Client);
bool isAddressIteratorCompleted;
Results.ResolutionResult addressResult = AddressIterator.GetNextResult(out isAddressIteratorCompleted, selected);
if (isAddressIteratorCompleted)
{
// remember the last result from the subsequent iteration
ResolvedAddresses = AddressIterator.GetAddresses(addressResult).ToArray();
if (!ResolvedAddresses.Any())
{
// Failed to resolve
isCompleted = true;
}
LastAddressResult = addressResult;
AddressIterator.Dispose();
AddressIterator = null;
}
isCompleted = false;
return(addressResult);
}
// Apply address result from previous step.
if (!object.ReferenceEquals(null, LastAddressResult))
{
// An address iteration has been completed in the previous step.
try
{
// Apply the resulting address records to the selected authority.
IEnumerable <DnsClient.DNS.Records.Address> addresses;
if (LastAddressResult.Response.Header.AA)
{
// fetch addresses from authoritative respone
addresses = LastAddressResult.Response.AnswerRecords.OfType <
DnsClient.DNS.Records.Address>().Where(a => StoredAuthorities.Selected.Name.Equals(a.Base.NAME));
}
else
{
// fetch address from additional records
addresses = LastAddressResult.Response.AdditionalRecords.OfType <
DnsClient.DNS.Records.Address>().Where(a => StoredAuthorities.Selected.Name.Equals(a.Base.NAME));
}
if (addresses.Any())
{
StoredAuthorities.Selected.ApplyAddresses(addresses);
OnNameServerResolved(StoredAuthorities.Selected);
}
}
finally
{
LastAddressResult = null;
}
}
else
{
// The standard case
// Ensure StoredAuthorities with a resolved selected name server.
if (object.ReferenceEquals(null, StoredAuthorities)) // initial state
{
StoredAuthorities = GetStartAuthorities();
OnResolutionStart(StoredAuthorities);
}
else
{
OnResolutionContinue(StoredAuthorities);
}
// apply cached address records to the set of authorities
StoredAuthorities.ApplyCache(AddressCache);
// Select randomly any name server unless one was explicitly chosen.
if (!object.ReferenceEquals(null, selected))
{
StoredAuthorities.SelectOne(selected);
}
else
{
selected = StoredAuthorities.SelectAny();
}
OnAuthoritySelected(StoredAuthorities);
if (!selected.IsResolved)
{
// start a subsequent iteration to resolve the selected name server
OnNameServerResolution(selected);
AddressIterator = CreateAddressIterator(selected.Name);
return(GetNextResult(out isCompleted, null));
}
}
// Perform the actual name server request.
Results.ResolutionResult result = Request(StoredAuthorities, out isCompleted);
try // Internal.QueryException
{
Internal.QueryProcessor query = new Internal.QueryProcessor(Resolver.Domain, Question, result.Response);
Internal.QueryResult qr = query.Process();
result.QueryState = qr.State;
switch (qr.State)
{
case QueryState.NextAuthorities:
//StoredAuthorities = GetResultAuthorities(result);
isCompleted = false;
OnNextAuthorities(StoredAuthorities.Selected, qr.NextAuthorities);
StoredAuthorities = qr.NextAuthorities;
result.NextAuthorities = StoredAuthorities;
// "Received {1} '{0}' authorities from '{2}'."
//LogMessageCreate(Logging.LogMessageText.RESPONSE.INFO.NextAuthoritiesReceived( StoredAuthorities.Selected, result.NextAuthorities));
break;
case QueryState.FollowCName:
// CNAME found.
isCompleted = true;
OnCNameFound(qr.CanonicalName);
// Follow, if it's configured.
if (Resolver.Options.FollowCanonical)
{
// Start a new iteration with the canonical name and the same question.
// Name servers may or may not be given.
CNameIterator = CreateCNameIterator(qr.CanonicalName, qr.NextAuthorities);
isCompleted = false;
}
break;
case QueryState.NonAuthoritativeAnswer:
isCompleted = true;
OnResolutionSucceeded(result.Response, qr.Answers);
break;
case QueryState.AuthoritativeAnswer:
// At least one record of the requested type was found.
isCompleted = true;
OnResolutionSucceeded(result.Response, qr.Answers);
break;
case QueryState.NxDomain:
isCompleted = true;
LogMessageCreate(Logging.LogMessageText.RESPONSE.ERROR.NameNotExisting(qr.CanonicalName ?? Resolver.Domain));
break;
case QueryState.NoData:
case QueryState.EmptyResponse:
isCompleted = true;
LogMessageCreate(Logging.LogMessageText.RESPONSE.ERROR.NegativeResponse(qr.State));
break;
case QueryState.UnexpectedRCode:
isCompleted = true;
OnRCodeNonZero(result.Response);
break;
}
}
catch (Internal.QueryException ex)
{
isCompleted = true;
result.QueryState = ex.State;
LogMessageCreate(Logging.LogMessageText.RESPONSE.ERROR.ResponseInvalid(ex.State));
}
return(result);
// =====================================================================
#region hidden
//// Dealing with non-Zero RCODE.
//if (isCompleted && result.Response.Header.RCODE != DnsClient.DNS.RCODE.NoError)
//{
// OnRCodeNonZero(result.Response);
// return result;
//}
//// cache response address records
//AddressCache.Set(result.Response.AnswerRecords.OfType<DnsClient.DNS.Records.Address>());
//if (!Resolver.Options.StrictAuhtoritative) // optionally cache also additional address records
//{
// AddressCache.Set(result.Response.AdditionalRecords.Select<DnsClient.DNS.Records.Address>());
//}
//if (result.Response.Header.TC)
//{
// // If the result was truncated, the request can be repeated once.
// if (Resolver.Options.RepeatTruncated && !TCRepeating)
// {
// TCRepeating = true;
// isCompleted = false;
// OnRepeatTruncated();
// return result;
// }
//}
//TCRepeating = false;
//if (isCompleted)
//{
// // There was an authoritative response.
// DnsClient.DNS.Records.SOA soa = result.Response.AnswerRecords.OfType<DnsClient.DNS.Records.SOA>().FirstOrDefault();
// // answer records matching the question
// IEnumerable<DnsClient.DNS.RR> requested = result.Response.AnswerRecords;
// if (Question != DnsClient.DNS.QTYPE.ANY)
// {
// // A particular record type has been queried (not ANY).
// requested = requested.OfQuestion(Question);
// }
// if (requested.Any())
// {
// // At least one record of the requested type was found.
// OnResolutionSucceeded(result.Response, requested);
// }
// // check for CNAME
// //
// // [RFC 1034], 5.2.2. Aliases
// //
// // In most cases a resolver simply restarts the query at the new name when
// // it encounters a CNAME. However, when performing the general function,
// // the resolver should not pursue aliases when the CNAME RR matches the
// // query type. This allows queries which ask whether an alias is present.
// // For example, if the query type is CNAME, the user is interested in the
// // CNAME RR itself, and not the RRs at the name it points to.
// DnsClient.DNS.Records.CNAME cname;
// if (!object.ReferenceEquals(null, (
// cname = result.Response.AnswerRecords.FirstOrDefault<DnsClient.DNS.Records.CNAME>())))
// {
// // CNAME found.
// //OnCNameFound(cname);
// if (Question != DnsClient.DNS.QTYPE.CNAME)
// {
// // A CNAME can lead to the zone itself.
// if (!object.ReferenceEquals(null, soa) &&
// DnsDomain.Equals(soa.Base.NAME, cname.CANONICAL))
// {
// // TODO
// }
// }
// // Follow, if it's configured and the question was not CNAME.
// if (!Question.Equals(DnsClient.DNS.QTYPE.CNAME) &&
// Resolver.Options.FollowCanonical)
// {
// // Start a new iteration with the canonical name and the same question.
// CNameIterator = CreateCNameIterator((DnsDomain)cname.CANONICAL);
// isCompleted = false;
// }
// }
// else
// {
// // no matching CNAME found
// if (!requested.Any())
// {
// // Neither an appropriate CNAME nor the requested RR type was found.
// OnMissingRecords(result.Response);
// }
// }
// if (NestingLevel == 0)
// {
// // "Resolution finished."
// LogMessageCreate(Logging.LogMessageText.RESPONSE.INFO.ResolutionFinished(IterationCount));
// }
//}
//else
//{
// // The iteration is not yet completed: get authorities for the next step.
// StoredAuthorities = GetResultAuthorities(result);
// result.NextAuthorities = StoredAuthorities;
// if (StoredAuthorities.IsEmpty)
// throw new ResolverException(
// "No authority name servers were found although the respone is non-authoritative.");
// // "Received {1} '{0}' authorities from '{2}'."
// LogMessageCreate(Logging.LogMessageText.RESPONSE.INFO.NextAuthoritiesReceived(result.Authorities.Selected, result.NextAuthorities));
//}
//return result;
#endregion
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
try
{
if (AddressIterator != null)
((IDisposable)AddressIterator).Dispose();
if (CNameIterator != null)
((IDisposable)CNameIterator).Dispose();
}
finally
{
AddressIterator = null;
CNameIterator = null;
}
}
base.Dispose(disposing);
}
protected override Results.ResolutionResult GetNextResult(out bool isCompleted, NameServer selected)
{
// Iteration may be delegated to CNameIterator if the requested name
// has been identified as alias.
if (!object.ReferenceEquals(null, CNameIterator))
{
CNameIterator.EnsureConnection(Resolver.Client);
return CNameIterator.GetNextResult(out isCompleted, selected);
}
// A subsequent iteration may be running if a name server address needs to be resolved.
if (!object.ReferenceEquals(null, AddressIterator))
{
AddressIterator.EnsureConnection(Resolver.Client);
bool isAddressIteratorCompleted;
Results.ResolutionResult addressResult = AddressIterator.GetNextResult(out isAddressIteratorCompleted, selected);
if (isAddressIteratorCompleted)
{
// remember the last result from the subsequent iteration
ResolvedAddresses = AddressIterator.GetAddresses(addressResult).ToArray();
if (!ResolvedAddresses.Any())
{
// Failed to resolve
isCompleted = true;
}
LastAddressResult = addressResult;
AddressIterator.Dispose();
AddressIterator = null;
}
isCompleted = false;
return addressResult;
}
// Apply address result from previous step.
if (!object.ReferenceEquals(null, LastAddressResult))
{
// An address iteration has been completed in the previous step.
try
{
// Apply the resulting address records to the selected authority.
IEnumerable<DnsClient.DNS.Records.Address> addresses;
if (LastAddressResult.Response.Header.AA)
{
// fetch addresses from authoritative respone
addresses = LastAddressResult.Response.AnswerRecords.OfType<
DnsClient.DNS.Records.Address>().Where(a => StoredAuthorities.Selected.Name.Equals(a.Base.NAME));
}
else
{
// fetch address from additional records
addresses = LastAddressResult.Response.AdditionalRecords.OfType<
DnsClient.DNS.Records.Address>().Where(a => StoredAuthorities.Selected.Name.Equals(a.Base.NAME));
}
if (addresses.Any())
{
StoredAuthorities.Selected.ApplyAddresses(addresses);
OnNameServerResolved(StoredAuthorities.Selected);
}
}
finally
{
LastAddressResult = null;
}
}
else
{
// The standard case
// Ensure StoredAuthorities with a resolved selected name server.
if (object.ReferenceEquals(null, StoredAuthorities)) // initial state
{
StoredAuthorities = GetStartAuthorities();
OnResolutionStart(StoredAuthorities);
}
else
{
OnResolutionContinue(StoredAuthorities);
}
// apply cached address records to the set of authorities
StoredAuthorities.ApplyCache(AddressCache);
// Select randomly any name server unless one was explicitly chosen.
if (!object.ReferenceEquals(null, selected))
{
StoredAuthorities.SelectOne(selected);
}
else
{
selected = StoredAuthorities.SelectAny();
}
OnAuthoritySelected(StoredAuthorities);
if (!selected.IsResolved)
{
// start a subsequent iteration to resolve the selected name server
OnNameServerResolution(selected);
AddressIterator = CreateAddressIterator(selected.Name);
return GetNextResult(out isCompleted, null);
}
}
// Perform the actual name server request.
Results.ResolutionResult result = Request(StoredAuthorities, out isCompleted);
try // Internal.QueryException
{
Internal.QueryProcessor query = new Internal.QueryProcessor(Resolver.Domain, Question, result.Response);
Internal.QueryResult qr = query.Process();
result.QueryState = qr.State;
switch (qr.State)
{
case QueryState.NextAuthorities:
//StoredAuthorities = GetResultAuthorities(result);
isCompleted = false;
OnNextAuthorities(StoredAuthorities.Selected, qr.NextAuthorities);
StoredAuthorities = qr.NextAuthorities;
result.NextAuthorities = StoredAuthorities;
// "Received {1} '{0}' authorities from '{2}'."
//LogMessageCreate(Logging.LogMessageText.RESPONSE.INFO.NextAuthoritiesReceived( StoredAuthorities.Selected, result.NextAuthorities));
break;
case QueryState.FollowCName:
// CNAME found.
isCompleted = true;
OnCNameFound(qr.CanonicalName);
// Follow, if it's configured.
if (Resolver.Options.FollowCanonical)
{
// Start a new iteration with the canonical name and the same question.
// Name servers may or may not be given.
CNameIterator = CreateCNameIterator(qr.CanonicalName, qr.NextAuthorities);
isCompleted = false;
}
break;
case QueryState.NonAuthoritativeAnswer:
isCompleted = true;
OnResolutionSucceeded(result.Response, qr.Answers);
break;
case QueryState.AuthoritativeAnswer:
// At least one record of the requested type was found.
isCompleted = true;
OnResolutionSucceeded(result.Response, qr.Answers);
break;
case QueryState.NxDomain:
isCompleted = true;
LogMessageCreate(Logging.LogMessageText.RESPONSE.ERROR.NameNotExisting(qr.CanonicalName ?? Resolver.Domain));
break;
case QueryState.NoData:
case QueryState.EmptyResponse:
isCompleted = true;
LogMessageCreate(Logging.LogMessageText.RESPONSE.ERROR.NegativeResponse(qr.State));
break;
case QueryState.UnexpectedRCode:
isCompleted = true;
OnRCodeNonZero(result.Response);
break;
}
}
catch (Internal.QueryException ex)
{
isCompleted = true;
result.QueryState = ex.State;
LogMessageCreate(Logging.LogMessageText.RESPONSE.ERROR.ResponseInvalid(ex.State));
}
return result;
// =====================================================================
#region hidden
//// Dealing with non-Zero RCODE.
//if (isCompleted && result.Response.Header.RCODE != DnsClient.DNS.RCODE.NoError)
//{
// OnRCodeNonZero(result.Response);
// return result;
//}
//// cache response address records
//AddressCache.Set(result.Response.AnswerRecords.OfType<DnsClient.DNS.Records.Address>());
//if (!Resolver.Options.StrictAuhtoritative) // optionally cache also additional address records
//{
// AddressCache.Set(result.Response.AdditionalRecords.Select<DnsClient.DNS.Records.Address>());
//}
//if (result.Response.Header.TC)
//{
// // If the result was truncated, the request can be repeated once.
// if (Resolver.Options.RepeatTruncated && !TCRepeating)
// {
// TCRepeating = true;
// isCompleted = false;
// OnRepeatTruncated();
// return result;
// }
//}
//TCRepeating = false;
//if (isCompleted)
//{
// // There was an authoritative response.
// DnsClient.DNS.Records.SOA soa = result.Response.AnswerRecords.OfType<DnsClient.DNS.Records.SOA>().FirstOrDefault();
// // answer records matching the question
// IEnumerable<DnsClient.DNS.RR> requested = result.Response.AnswerRecords;
// if (Question != DnsClient.DNS.QTYPE.ANY)
// {
// // A particular record type has been queried (not ANY).
// requested = requested.OfQuestion(Question);
// }
// if (requested.Any())
// {
// // At least one record of the requested type was found.
// OnResolutionSucceeded(result.Response, requested);
// }
// // check for CNAME
// //
// // [RFC 1034], 5.2.2. Aliases
// //
// // In most cases a resolver simply restarts the query at the new name when
// // it encounters a CNAME. However, when performing the general function,
// // the resolver should not pursue aliases when the CNAME RR matches the
// // query type. This allows queries which ask whether an alias is present.
// // For example, if the query type is CNAME, the user is interested in the
// // CNAME RR itself, and not the RRs at the name it points to.
// DnsClient.DNS.Records.CNAME cname;
// if (!object.ReferenceEquals(null, (
// cname = result.Response.AnswerRecords.FirstOrDefault<DnsClient.DNS.Records.CNAME>())))
// {
// // CNAME found.
// //OnCNameFound(cname);
// if (Question != DnsClient.DNS.QTYPE.CNAME)
// {
// // A CNAME can lead to the zone itself.
// if (!object.ReferenceEquals(null, soa) &&
// DnsDomain.Equals(soa.Base.NAME, cname.CANONICAL))
// {
// // TODO
// }
// }
// // Follow, if it's configured and the question was not CNAME.
// if (!Question.Equals(DnsClient.DNS.QTYPE.CNAME) &&
// Resolver.Options.FollowCanonical)
// {
// // Start a new iteration with the canonical name and the same question.
// CNameIterator = CreateCNameIterator((DnsDomain)cname.CANONICAL);
// isCompleted = false;
// }
// }
// else
// {
// // no matching CNAME found
// if (!requested.Any())
// {
// // Neither an appropriate CNAME nor the requested RR type was found.
// OnMissingRecords(result.Response);
// }
// }
// if (NestingLevel == 0)
// {
// // "Resolution finished."
// LogMessageCreate(Logging.LogMessageText.RESPONSE.INFO.ResolutionFinished(IterationCount));
// }
//}
//else
//{
// // The iteration is not yet completed: get authorities for the next step.
// StoredAuthorities = GetResultAuthorities(result);
// result.NextAuthorities = StoredAuthorities;
// if (StoredAuthorities.IsEmpty)
// throw new ResolverException(
// "No authority name servers were found although the respone is non-authoritative.");
// // "Received {1} '{0}' authorities from '{2}'."
// LogMessageCreate(Logging.LogMessageText.RESPONSE.INFO.NextAuthoritiesReceived(result.Authorities.Selected, result.NextAuthorities));
//}
//return result;
#endregion
}