minor improvements

Author: jstedfast

MimeKit/Encodings/Base64Validator.cs

@@ -103,21 +103,32 @@ unsafe void Validate (ref byte table, byte* input, int length)
 					byte rank = Unsafe.Add (ref table, c);
 
 					if (rank == 0xFF) {
+						// The current byte is outside of the base64 alphabet, but could be whitespace (which we will treat as valid).
 						if (c == (byte) '\n') {
 							if (octets % 4 != 0)
 								reader.OnMimeComplianceViolation (MimeComplianceViolation.IncompleteBase64Quantum, streamOffset, lineNumber);
 
 							lineNumber++;
 							octets = 0;
 						} else if (!c.IsWhitespace ()) {
+							// This is an invalid base64 character.
 							reader.OnMimeComplianceViolation (MimeComplianceViolation.InvalidBase64Character, streamOffset, lineNumber);
 						}
 					} else if (c == (byte) '=') {
+						// An '=' char is a valid base64 character, but is special and indicates the end of the content (other than additional padding).
+						if (octets % 4 < 2) {
+							// Padding is only valid in the last 2 positions of the final quantum.
+							reader.OnMimeComplianceViolation (MimeComplianceViolation.InvalidBase64Padding, streamOffset, lineNumber);
+							invalid = true;
+							return;
+						}
+
 						streamOffset++;
 						padding = 1;
 						octets++;
 						break;
 					} else {
+						// Increment the number of octets in this base64 quantum (a quantum is a series of 4 octets).
 						octets++;
 					}
 

MimeKit/Encodings/QuotedPrintableValidator.cs

@@ -135,16 +135,14 @@ unsafe void Validate (byte* input, int length)
 					inptr++;
 					break;
 				case QpValidatorState.SoftBreak:
-					c = *inptr;
-
-					if (c == '\n') {
+					if (*inptr == '\n') {
 						lineNumber++;
+						inptr++;
 					} else {
 						reader.OnMimeComplianceViolation (MimeComplianceViolation.InvalidQuotedPrintableSoftBreak, streamOffset + (inptr - input), lineNumber);
 					}
 
 					state = QpValidatorState.PassThrough;
-					inptr++;
 					break;
 				case QpValidatorState.DecodeByte:
 					c = *inptr;