Updated PemReader to support differing whitespace assumptions.

Added tests.
Issue #2

1 files changed, 318 insertions, 37 deletions

diff --git a/crypto/src/util/io/pem/PemReader.cs b/crypto/src/util/io/pem/PemReader.cs
index 7e6252b9b..008a03524 100644
--- a/crypto/src/util/io/pem/PemReader.cs
+++ b/crypto/src/util/io/pem/PemReader.cs
@@ -1,24 +1,32 @@
 using System;
 using System.Collections;
 using System.IO;
-using System.Text;
+
 
 using Org.BouncyCastle.Utilities.Encoders;
 
 namespace Org.BouncyCastle.Utilities.IO.Pem
 {
-	public class PemReader
-	{
-		private const string BeginString = "-----BEGIN ";
-		private const string EndString = "-----END ";
 
+	public class PemReader
+	{		
 		private readonly TextReader reader;
+		private readonly MemoryStream buffer;
+		private readonly StreamWriter textBuffer;
+		private readonly IList pushback = Platform.CreateArrayList();
+		int c = 0;
+
+		
 
 		public PemReader(TextReader reader)
 		{
 			if (reader == null)
 				throw new ArgumentNullException("reader");
 
+
+			buffer = new MemoryStream();
+			textBuffer = new StreamWriter(buffer);
+
 			this.reader = reader;
 		}
 
@@ -27,64 +35,337 @@ namespace Org.BouncyCastle.Utilities.IO.Pem
 			get { return reader; }
 		}
 
+
 		/// <returns>
 		/// A <see cref="PemObject"/>
 		/// </returns>
-		/// <exception cref="IOException"></exception>
+		/// <exception cref="IOException"></exception>	
 		public PemObject ReadPemObject()
-		{
-            string line = reader.ReadLine();
+        {
 
-            while (line != null && !Platform.StartsWith(line, BeginString)) 
+			//
+			// Look for BEGIN
+			//
+
+			for (; ; )
+			{
+
+				// Seek a leading dash, ignore anything up to that point.
+				if (!seekDash())
+				{
+					// There are no pem objects here.
+					return null; 
+				}
+
+
+				// consume dash [-----]BEGIN ...
+				if (!consumeDash())
+				{
+					throw new IOException("no data after consuming leading dashes");
+				}
+
+
+				skipWhiteSpace();
+
+
+				if (!expect("BEGIN"))
+				{
+					continue;
+				}
+
+				break;
+
+			}
+
+
+			skipWhiteSpace();
+
+			//
+			// Consume type, accepting whitespace
+			//
+
+			if (!bufferUntilStopChar('-',false) )
             {
-                line = reader.ReadLine();
-            }
+				throw new IOException("ran out of data before consuming type");
+			}
+
+			string type = bufferedString().Trim();
 
-            if (line != null)
+
+			// Consume dashes after type.
+
+			if (!consumeDash())
+            {
+				throw new IOException("ran out of data consuming header");
+			}
+
+			skipWhiteSpace();
+
+
+			//
+			// Read ahead looking for headers.
+			// Look for a colon for up to 64 characters, as an indication there might be a header.
+			//
+
+			IList headers = Platform.CreateArrayList();
+
+			while (seekColon(64))
             {
-                line = line.Substring(BeginString.Length);
-                int index = line.IndexOf('-');
 
-                if (index > 0 && Platform.EndsWith(line, "-----") && (line.Length - index) == 5)
+				if (!bufferUntilStopChar(':',false))
                 {
-                    string type = line.Substring(0, index);
+					throw new IOException("ran out of data reading header key value");
+				}
+
+				string key = bufferedString().Trim();
+
 
-                    return LoadObject(type);
+				c = Read();
+				if (c != ':')
+                {
+					throw new IOException("expected colon");
                 }
-            }
+				
+
+				//
+				// We are going to look for well formed headers, if they do not end with a "LF" we cannot
+				// discern where they end.
+				//
+			
+				if (!bufferUntilStopChar('\n', false)) // Now read to the end of the line.
+                {
+					throw new IOException("ran out of data before consuming header value");
+				}
+
+				skipWhiteSpace();
+
+				string value = bufferedString().Trim();
+				headers.Add(new PemHeader(key,value));
+			}
+
+
+			//
+			// Consume payload, ignoring all white space until we encounter a '-'
+			//
+
+			skipWhiteSpace();
+
+			if (!bufferUntilStopChar('-',true))
+			{
+				throw new IOException("ran out of data before consuming payload");
+			}
+
+			string payload = bufferedString();
+		
+			// Seek the start of the end.
+			if (!seekDash())
+			{
+				throw new IOException("did not find leading '-'");
+			}
+
+			if (!consumeDash())
+			{
+				throw new IOException("no data after consuming trailing dashes");
+			}
+
+			if (!expect("END "+type))
+			{
+				throw new IOException("END "+type+" was not found.");
+			}
+
+
+
+			if (!seekDash())
+			{
+				throw new IOException("did not find ending '-'");
+			}
+
+
+			// consume trailing dashes.
+			consumeDash();
+			
+
+			return new PemObject(type, headers, Base64.Decode(payload));
 
-            return null;
 		}
 
-		private PemObject LoadObject(string type)
+
+	
+		private string bufferedString()
+        {
+			textBuffer.Flush();
+			string value = Strings.FromUtf8ByteArray(buffer.ToArray());
+			buffer.Position = 0;
+			buffer.SetLength(0);
+			return value;
+        }
+
+
+		private bool seekDash()
+        {
+			c = 0;
+			while((c = Read()) >=0)
+            {
+				if (c == '-')
+                {
+					break;
+                }
+            }
+
+			PushBack(c);
+
+			return c == '-';
+        }
+
+
+		/// <summary>
+		/// Seek ':" up to the limit.
+		/// </summary>
+		/// <param name="upTo"></param>
+		/// <returns></returns>
+		private bool seekColon(int upTo)
 		{
-			string endMarker = EndString + type;
-			IList headers = Platform.CreateArrayList();
-			StringBuilder buf = new StringBuilder();
+			c = 0;
+			bool colonFound = false;
+			IList read = Platform.CreateArrayList();
+
+			for (; upTo>=0 && c >=0; upTo--)
+            {
+				c = Read();
+				read.Add(c);
+				if (c == ':')
+                {
+					colonFound = true;
+					break;
+                }
+            }
 
-			string line;
-			while ((line = reader.ReadLine()) != null)
+			while(read.Count>0)
+            {
+				PushBack((int)read[read.Count-1]);
+				read.RemoveAt(read.Count-1);
+            }
+
+			return colonFound;
+		}
+
+
+
+		/// <summary>
+		/// Consume the dashes
+		/// </summary>
+		/// <returns></returns>
+		private bool consumeDash()
+        {
+			c = 0;
+			while ((c = Read()) >= 0)
 			{
-				int colonPos = line.IndexOf(':');
-				if (colonPos >= 0)
+				if (c != '-')
 				{
-                    string hdr = line.Substring(0, colonPos);
-                    string val = line.Substring(colonPos + 1).Trim();
+					break;
+				}
+			}
 
-                    headers.Add(new PemHeader(hdr, val));
-                    continue;
+			PushBack(c);
+
+			return c != -1;
+		}
+
+		/// <summary>
+		/// Skip white space leave char in stream.
+		/// </summary>
+		private void skipWhiteSpace()
+        {
+			while ((c = Read()) >= 0)
+			{
+				if (c > ' ')
+				{
+					break;
 				}
+			}
+			PushBack(c);
+		}
 
-                if (Platform.IndexOf(line, endMarker) >= 0)
-                    break;
+		/// <summary>
+		/// Read forward consuming the expected string.
+		/// </summary>
+		/// <param name="value">expected string</param>
+		/// <returns>false if not consumed</returns>
 
-                buf.Append(line.Trim());
+		private bool expect(String value)
+        {
+			for (int t=0; t<value.Length; t++)
+            {
+				c = Read();
+				if (c == value[t])
+                {
+					continue;
+                } else
+                {
+					return false;
+                }
             }
 
-            if (line == null)
-				throw new IOException(endMarker + " not found");
+			return true;
+        }
+		
+
+		/// <summary>
+		/// Consume until dash.
+		/// </summary>
+		/// <returns>true if stream end not met</returns>
+		private bool bufferUntilStopChar(char stopChar,   bool skipWhiteSpace)
+        {
+			while ((c = Read()) >= 0)
+			{	
+				if (skipWhiteSpace && c <=' ')
+                {
+					continue;
+                }
 
-			return new PemObject(type, headers, Base64.Decode(buf.ToString()));
+				if (c != stopChar)
+				{
+					textBuffer.Write((char)c);
+					textBuffer.Flush();
+					
+				} else
+                {
+					  PushBack(c);
+					break;
+                }
+			}
+			
+			return c > -1;
 		}
+
+
+
+		private void PushBack(int value)
+        {
+			if (pushback.Count == 0)
+            {
+				pushback.Add(value);
+            } else
+            {
+				pushback.Insert(0, value);
+            }
+        }
+
+
+		private int Read()
+        {
+			if (pushback.Count>0)
+            {
+				int i = (int)pushback[0];
+				pushback.RemoveAt(0);
+				return i;
+            }
+
+			return reader.Read();
+        }
+
+
+
+
 	}
 }