internal static NameServerCollection Create(
IEnumerable <DnsClient.DNS.RR> records, IEnumerable <DnsClient.DNS.RR> addresses = null)
{
// NS records from Authority Section
IEnumerable <DnsClient.DNS.Records.NS> nsRecords = records.Select <DnsClient.DNS.Records.NS>();
DnsClient.DNS.Records.NS ns1 = nsRecords.FirstOrDefault();
if (ns1 == null)
{
return(Empty);
}
// There are NS RRs.
NameServerCollection result = new NameServerCollection(
(DnsDomain)ns1.Base.NAME, nsRecords.Select(ns => new NameServer(
(DnsDomain)ns.Base.NAME, (DnsDomain)ns.NSDNAME)));
// Apply address records from Additional Section (A or AAAA) if any
if (addresses != null)
{
foreach (DnsClient.DNS.Records.Address addr in addresses.Select(
rr => rr as DnsClient.DNS.Records.Address).Where(a => a != null))
{
DnsDomain name = DnsDomain.Parse(addr.Base.NAME);
if (result.NameServers.ContainsKey(name))
{
result.NameServers[name].Addresses.Add(addr.ADDRESS);
}
}
}
return(result);
}
internal static NameServerCollection Find(DnsDomain domain,
IEnumerable <DnsClient.DNS.RR> records, IEnumerable <DnsClient.DNS.RR> addresses)
{
// [RFC 1034]
// 5.3.3. Algorithm
//
// 2. Find the best servers to ask.
//
// Step 2 looks for a name server to ask for the required data. The
// general strategy is to look for locally-available name server RRs,
// starting at SNAME, then the parent domain name of SNAME, the
// grandparent, and so on toward the root. Thus if SNAME were
// Mockapetris.ISI.EDU, this step would look for NS RRs for
// Mockapetris.ISI.EDU, then ISI.EDU, then EDU, and then . (the root).
// These NS RRs list the names of hosts for a zone at or above SNAME. Copy
// the names into SLIST.
// NS records from Authority Section above domain (SNAME)
IEnumerable <DnsClient.DNS.Records.NS> nservers = records.Select <
DnsClient.DNS.Records.NS>().Where(ns => domain.IsBelow(ns.Base.NAME));
if (!nservers.Any())
{
return(Empty);
}
// There are relevant NS RRs.
NameServerCollection result = new NameServerCollection(
domain, nservers.Select(ns => new NameServer(
(DnsDomain)ns.Base.NAME, (DnsDomain)ns.NSDNAME)));
// Apply address records from Additional Section (A or AAAA) if any
if (!object.ReferenceEquals(null, addresses))
{
foreach (DnsClient.DNS.Records.Address addr in addresses.Select <
DnsClient.DNS.Records.Address>())
{
DnsDomain hostname = (DnsDomain)addr.Base.NAME;
if (result.NameServers.ContainsKey(hostname))
{
result.NameServers[hostname].Addresses.Add(addr.ADDRESS);
}
}
}
return(result);
}