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Netch/3rd/DnsClient.NET/DnsResponseHeader.cs

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+using DnsClient.Protocol;
+using System.Linq;
+
+namespace DnsClient
+{
+    /// <summary>
+    /// The header section of a <see cref="IDnsQueryResponse"/>.
+    /// </summary>
+    public class DnsResponseHeader
+    {
+        private readonly ushort _flags = 0;
+
+        /// <summary>
+        /// Gets the number of additional records in the <see cref="IDnsQueryResponse"/>.
+        /// </summary>
+        /// <value>
+        /// The number of additional records.
+        /// </value>
+        public int AdditionalCount { get; }
+
+        /// <summary>
+        /// Gets the number of answer records in the <see cref="IDnsQueryResponse"/>.
+        /// </summary>
+        /// <value>
+        /// The number of answer records.
+        /// </value>
+        public int AnswerCount { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether the future use flag is set.
+        /// </summary>
+        /// <value>
+        ///   The future use flag.
+        /// </value>
+        public bool FutureUse => HasFlag(DnsHeaderFlag.FutureUse);
+
+        /// <summary>
+        /// Gets a value indicating whether this instance has authority answers.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if this instance has authority answers; otherwise, <c>false</c>.
+        /// </value>
+        public bool HasAuthorityAnswer => HasFlag(DnsHeaderFlag.HasAuthorityAnswer);
+
+        internal DnsHeaderFlag HeaderFlags => (DnsHeaderFlag)_flags;
+
+        /// <summary>
+        /// Gets the identifier.
+        /// </summary>
+        /// <value>
+        /// The identifier.
+        /// </value>
+        public int Id { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether the result is authentic data.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if the result is authentic; otherwise, <c>false</c>.
+        /// </value>
+        public bool IsAuthenticData => HasFlag(DnsHeaderFlag.IsAuthenticData);
+
+        /// <summary>
+        /// Gets a value indicating whether checking is disabled.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if checking is disabled; otherwise, <c>false</c>.
+        /// </value>
+        public bool IsCheckingDisabled => HasFlag(DnsHeaderFlag.IsCheckingDisabled);
+
+        /// <summary>
+        /// Gets a value indicating whether this instance has a query.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if this instance has a query; otherwise, <c>false</c>.
+        /// </value>
+        public bool HasQuery => HasFlag(DnsHeaderFlag.HasQuery);
+
+        /// <summary>
+        /// Gets the number of name servers.
+        /// </summary>
+        /// <value>
+        /// The number of name servers.
+        /// </value>
+        public int NameServerCount { get; }
+
+        /// <summary>
+        /// Gets the kind of query defined by <see cref="DnsOpCode"/>.
+        /// </summary>
+        /// <value>
+        /// The query kind.
+        /// </value>
+        public DnsOpCode OPCode => (DnsOpCode)((DnsHeader.OPCodeMask & _flags) >> DnsHeader.OPCodeShift);
+
+        /// <summary>
+        /// Gets the number of questions of the <see cref="IDnsQueryResponse"/>.
+        /// </summary>
+        /// <value>
+        /// The number of questions.
+        /// </value>
+        public int QuestionCount { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether recursion is available on the DNS server.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if recursion is available; otherwise, <c>false</c>.
+        /// </value>
+        public bool RecursionAvailable => HasFlag(DnsHeaderFlag.RecursionAvailable);
+
+        /// <summary>
+        /// Gets the response code.
+        /// </summary>
+        /// <value>
+        /// The response code.
+        /// </value>
+        public DnsResponseCode ResponseCode => (DnsResponseCode)(_flags & DnsHeader.RCodeMask);
+
+        /// <summary>
+        /// Gets a value indicating whether the result was truncated.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if the result was truncated; otherwise, <c>false</c>.
+        /// </value>
+        public bool ResultTruncated => HasFlag(DnsHeaderFlag.ResultTruncated);
+
+        /// <summary>
+        /// Gets a value indicating whether recursion desired flag was set by the request.
+        /// </summary>
+        /// <value>
+        ///   <c>true</c> if the recursion desired flag was set; otherwise, <c>false</c>.
+        /// </value>
+        public bool RecursionDesired => HasFlag(DnsHeaderFlag.RecursionDesired);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DnsResponseHeader"/> class.
+        /// </summary>
+        /// <param name="id">The identifier.</param>
+        /// <param name="flags">The flags.</param>
+        /// <param name="questionCount">The question count.</param>
+        /// <param name="answerCount">The answer count.</param>
+        /// <param name="additionalCount">The additional count.</param>
+        /// <param name="serverCount">The server count.</param>
+        public DnsResponseHeader(int id, ushort flags, int questionCount, int answerCount, int additionalCount, int serverCount)
+        {
+            Id = id;
+            _flags = flags;
+            QuestionCount = questionCount;
+            AnswerCount = answerCount;
+            AdditionalCount = additionalCount;
+            NameServerCount = serverCount;
+        }
+
+        private bool HasFlag(DnsHeaderFlag flag) => (HeaderFlags & flag) != 0;
+
+        /// <summary>
+        /// Returns a <see cref="System.String" /> that represents this instance.
+        /// </summary>
+        /// <returns>
+        /// A <see cref="System.String" /> that represents this instance.
+        /// </returns>
+        public override string ToString()
+        {
+            var head = $";; ->>HEADER<<- opcode: {OPCode}, status: {DnsResponseCodeText.GetErrorText(ResponseCode)}, id: {Id}";
+            var flags = new string[] {
+                        HasQuery ? "qr" : "",
+                        HasAuthorityAnswer ? "aa" : "",
+                        RecursionDesired ? "rd" : "",
+                        RecursionAvailable ? "ra" : "",
+                        ResultTruncated ? "tc" : "",
+                        IsCheckingDisabled ? "cd" : "",
+                        IsAuthenticData ? "ad" : ""
+                    };
+
+            var flagsString = string.Join(" ", flags.Where(p => p != ""));
+            return $"{head}\r\n;; flags: {flagsString}; QUERY: {QuestionCount}, " +
+                $"ANSWER: {AnswerCount}, AUTORITY: {NameServerCount}, ADDITIONAL: {AdditionalCount}";
+        }
+    }
+}