done

2026-05-09 22:54:03 +08:00 · 2019-12-02 19:51:12 +08:00
commit b2ea730984
229 changed files with 86605 additions and 0 deletions
--- a/Netch/3rd/DnsClient.NET/Protocol/Options/OptRecord.cs
+++ b/Netch/3rd/DnsClient.NET/Protocol/Options/OptRecord.cs
@@ -0,0 +1,128 @@
+namespace DnsClient.Protocol.Options
+{
+    /* https://tools.ietf.org/html/rfc6891#section-4.3
+    6.1.2.  Wire Format
+
+   An OPT RR has a fixed part and a variable set of options expressed as
+   {attribute, value} pairs.  The fixed part holds some DNS metadata,
+   and also a small collection of basic extension elements that we
+   expect to be so popular that it would be a waste of wire space to
+   encode them as {attribute, value} pairs.
+
+   The fixed part of an OPT RR is structured as follows:
+
+       +------------+--------------+------------------------------+
+       | Field Name | Field Type   | Description                  |
+       +------------+--------------+------------------------------+
+       | NAME       | domain name  | MUST be 0 (root domain)      |
+       | TYPE       | u_int16_t    | OPT (41)                     |
+       | CLASS      | u_int16_t    | requestor's UDP payload size |
+       | TTL        | u_int32_t    | extended RCODE and flags     |
+       | RDLEN      | u_int16_t    | length of all RDATA          |
+       | RDATA      | octet stream | {attribute,value} pairs      |
+       +------------+--------------+------------------------------+
+
+    6.1.3.  OPT Record TTL Field Use
+
+   The extended RCODE and flags, which OPT stores in the RR Time to Live
+   (TTL) field, are structured as follows:
+
+                  +0 (MSB)                            +1 (LSB)
+       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
+    0: |         EXTENDED-RCODE        |            VERSION            |
+       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
+    2: | DO|                           Z                               |
+       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
+
+   EXTENDED-RCODE
+      Forms the upper 8 bits of extended 12-bit RCODE (together with the
+      4 bits defined in [RFC1035].  Note that EXTENDED-RCODE value 0
+      indicates that an unextended RCODE is in use (values 0 through
+      15).
+
+   VERSION
+      Indicates the implementation level of the setter.  Full
+      conformance with this specification is indicated by version '0'.
+      Requestors are encouraged to set this to the lowest implemented
+      level capable of expressing a transaction, to minimise the
+      responder and network load of discovering the greatest common
+      implementation level between requestor and responder.  A
+      requestor's version numbering strategy MAY ideally be a run-time
+      configuration option.
+      If a responder does not implement the VERSION level of the
+      request, then it MUST respond with RCODE=BADVERS.  All responses
+      MUST be limited in format to the VERSION level of the request, but
+      the VERSION of each response SHOULD be the highest implementation
+      level of the responder.  In this way, a requestor will learn the
+      implementation level of a responder as a side effect of every
+      response, including error responses and including RCODE=BADVERS.
+    */
+
+    /// <summary>
+    /// A options resource record.
+    /// </summary>
+    internal class OptRecord : DnsResourceRecord
+    {
+        private const uint ResponseCodeMask = 0xff000000;
+        private const int ResponseCodeShift = 20;
+        private const uint VersionMask = 0x00ff0000;
+        private const int VersionShift = 16;
+
+        public DnsResponseCode ResponseCodeEx
+        {
+            get
+            {
+                return (DnsResponseCode)((InitialTimeToLive & ResponseCodeMask) >> ResponseCodeShift);
+            }
+            set
+            {
+                InitialTimeToLive &= (int)~ResponseCodeMask;
+                InitialTimeToLive |= (int)(((int)value << ResponseCodeShift) & ResponseCodeMask);
+            }
+        }
+
+        public short UdpSize
+        {
+            get { return (short)RecordClass; }
+        }
+
+        public byte Version
+        {
+            get
+            {
+                return (byte)((InitialTimeToLive & VersionMask) >> VersionShift);
+            }
+            set
+            {
+                InitialTimeToLive = (int)((uint)InitialTimeToLive & ~VersionMask);
+                InitialTimeToLive |= (int)((value << VersionShift) & VersionMask);
+            }
+        }
+
+        public bool IsDnsSecOk
+        {
+            get { return (InitialTimeToLive & 0x8000) != 0; }
+            set
+            {
+                if (value)
+                {
+                    InitialTimeToLive |= 0x8000;
+                }
+                else
+                {
+                    InitialTimeToLive &= 0x7fff;
+                }
+            }
+        }
+
+        public OptRecord(int size = 4096, int version = 0, int length = 0)
+            : base(new ResourceRecordInfo(DnsString.RootLabel, ResourceRecordType.OPT, (QueryClass)size, version, length))
+        {
+        }
+
+        private protected override string RecordToString()
+        {
+            return $"OPT {RecordClass}.";
+        }
+    }
+}