PEMParser.cs :  » PDF » iTextSharp » Org » BouncyCastle » X509 » C# / CSharp Open Source

using System;
using System.IO;
using System.Text;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Utilities.Encoders;

namespace Org.BouncyCastle.X509{
  class PemParser
  {
    private readonly string _header1;
    private readonly string _header2;
    private readonly string _footer1;
    private readonly string _footer2;

    internal PemParser(
      string type)
    {
      _header1 = "-----BEGIN " + type + "-----";
      _header2 = "-----BEGIN X509 " + type + "-----";
      _footer1 = "-----END " + type + "-----";
      _footer2 = "-----END X509 " + type + "-----";
    }

    private string ReadLine(
      Stream inStream)
    {
      int c;
      StringBuilder l = new StringBuilder();

      do
      {
        while (((c = inStream.ReadByte()) != '\r') && c != '\n' && (c >= 0))
        {
          if (c == '\r')
          {
            continue;
          }

          l.Append((char)c);
        }
      }
      while (c >= 0 && l.Length == 0);

      if (c < 0)
      {
        return null;
      }

      return l.ToString();
    }

    internal Asn1Sequence ReadPemObject(
      Stream inStream)
    {
      string line;
      StringBuilder pemBuf = new StringBuilder();

      while ((line = ReadLine(inStream)) != null)
      {
        if (line.StartsWith(_header1) || line.StartsWith(_header2))
        {
          break;
        }
      }

      while ((line = ReadLine(inStream)) != null)
      {
        if (line.StartsWith(_footer1) || line.StartsWith(_footer2))
        {
          break;
        }

        pemBuf.Append(line);
      }

      if (pemBuf.Length != 0)
      {
        Asn1Object o = Asn1Object.FromByteArray(Base64.Decode(pemBuf.ToString()));

        if (!(o is Asn1Sequence))
        {
          throw new IOException("malformed PEM data encountered");
        }

        return (Asn1Sequence) o;
      }

      return null;
    }
  }
}