using System; using System.Collections.Generic; using System.Linq; #nullable enable using System.Net; using System.Threading.Tasks; namespace Swan.Net.Dns { /// /// DnsClient public methods. /// internal partial class DnsClient { private readonly IPEndPoint _dns; private readonly IDnsRequestResolver _resolver; public DnsClient(IPEndPoint dns, IDnsRequestResolver? resolver = null) { this._dns = dns; this._resolver = resolver ?? new DnsUdpRequestResolver(new DnsTcpRequestResolver()); } public DnsClient(IPAddress ip, Int32 port = Network.DnsDefaultPort, IDnsRequestResolver? resolver = null) : this(new IPEndPoint(ip, port), resolver) { } public DnsClientRequest Create(IDnsRequest? request = null) => new DnsClientRequest(this._dns, request, this._resolver); public async Task> Lookup(String domain, DnsRecordType type = DnsRecordType.A) { if(String.IsNullOrWhiteSpace(domain)) { throw new ArgumentNullException(nameof(domain)); } if(type != DnsRecordType.A && type != DnsRecordType.AAAA) { throw new ArgumentException("Invalid record type " + type); } DnsClientResponse response = await this.Resolve(domain, type).ConfigureAwait(false); List ips = response.AnswerRecords.Where(r => r.Type == type).Cast().Select(r => r.IPAddress).ToList(); return ips.Count == 0 ? throw new DnsQueryException(response, "No matching records") : ips; } public async Task Reverse(IPAddress ip) { if(ip == null) { throw new ArgumentNullException(nameof(ip)); } DnsClientResponse response = await this.Resolve(DnsDomain.PointerName(ip), DnsRecordType.PTR); IDnsResourceRecord ptr = response.AnswerRecords.FirstOrDefault(r => r.Type == DnsRecordType.PTR); return ptr == null ? throw new DnsQueryException(response, "No matching records") : ((DnsPointerResourceRecord)ptr).PointerDomainName.ToString(); } public Task Resolve(String domain, DnsRecordType type) => this.Resolve(new DnsDomain(domain), type); public Task Resolve(DnsDomain domain, DnsRecordType type) { DnsClientRequest request = this.Create(); DnsQuestion question = new DnsQuestion(domain, type); request.Questions.Add(question); request.OperationCode = DnsOperationCode.Query; request.RecursionDesired = true; return request.Resolve(); } } }