mcs/class/Mono.Security/Mono.Security.X509.Extensions/BasicConstraintsExtension.cs

   1 //
   2 // BasicConstraintsExtension.cs: Handles X.509 BasicConstrains extensions.
   3 //
   4 // Author:
   5 //      Sebastien Pouliot (spouliot@motus.com)
   6 //
   7 // (C) 2003 Motus Technologies Inc. (http://www.motus.com)
   8 //
   9
  10 using System;
  11 using System.Text;
  12
  13 using Mono.Security;
  14 using Mono.Security.X509;
  15
  16 namespace Mono.Security.X509.Extensions {
  17
  18         // References:
  19         // 1.   RFC 3280: Internet X.509 Public Key Infrastructure, Section 4.2.1.10
  20         //      http://www.ietf.org/rfc/rfc3280.txt
  21
  22         /* id-ce-basicConstraints OBJECT IDENTIFIER ::=  { id-ce 19 }
  23          *
  24          * BasicConstraints ::= SEQUENCE {
  25          *      cA                      BOOLEAN DEFAULT FALSE,
  26          *      pathLenConstraint       INTEGER (0..MAX) OPTIONAL
  27          * }
  28          */
  29         public class BasicConstraintsExtension : X509Extension {
  30
  31                 private bool cA;
  32                 private int pathLenConstraint;
  33
  34                 public BasicConstraintsExtension () : base ()
  35                 {
  36                         extnOid = "2.5.29.19";
  37                 }
  38
  39                 public BasicConstraintsExtension (ASN1 asn1) : base (asn1) {}
  40
  41                 public BasicConstraintsExtension (X509Extension extension) : base (extension) {}
  42
  43                 protected override void Decode ()
  44                 {
  45                         // default values
  46                         cA = false;
  47                         pathLenConstraint = 0; // no constraint
  48
  49                         ASN1 sequence = new ASN1 (extnValue.Value);
  50                         if (sequence.Tag != 0x30)
  51                                 throw new ArgumentException ("Invalid BasicConstraints extension");
  52                         int n = 0;
  53                         ASN1 a = sequence [n++];
  54                         if ((a != null) && (a.Tag == 0x01)) {
  55                                 cA = (a.Value [0] == 0xFF);
  56                                 a = sequence [n++];
  57                         }
  58                         if ((a != null) && (a.Tag == 0x02))
  59                                 pathLenConstraint = ASN1Convert.ToInt32 (a);
  60                 }
  61
  62                 protected override void Encode ()
  63                 {
  64                         if (extnValue == null) {
  65                                 extnValue = new ASN1 (0x30);
  66                                 if (cA)
  67                                         extnValue.Add (new ASN1 (0x01, new byte[] { 0xFF }));
  68                                 if (pathLenConstraint > 0)
  69                                         extnValue.Add (ASN1Convert.FromInt32 (pathLenConstraint));
  70                         }
  71                 }
  72
  73                 public bool CertificateAuthority {
  74                         get { return cA; }
  75                         set { cA = value; }
  76                 }
  77
  78                 public override string Name {
  79                         get { return "Basic Constraints"; }
  80                 }
  81
  82                 public int PathLenConstraint {
  83                         get { return pathLenConstraint; }
  84                         set { pathLenConstraint = value; }
  85                 }
  86
  87                 public override string ToString ()
  88                 {
  89                         StringBuilder sb = new StringBuilder ();
  90                         sb.Append ("Subject Type=");
  91                         sb.Append ((cA) ? "CA" : "End Entity");
  92                         sb.Append (Environment.NewLine);
  93                         sb.Append ("Path Length Constraint=");
  94                         if (pathLenConstraint == 0)
  95                                 sb.Append ("None");
  96                         else
  97                                 sb.Append (pathLenConstraint.ToString ());
  98                         sb.Append (Environment.NewLine);
  99                         return sb.ToString ();
 100                 }
 101         }
 102 }