imap: Implemented encoding RFC3501 strings.

* Was completely missing so far.
* Fixed bug in decoding that handled the "&-" sequence incorrectly.
* Added small test application that should easily be convertible to
  a unit test.

src/add-ons/mail_daemon/inbound_protocols/imap/imap_lib/Response.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2012, Axel Dörfler, axeld@pinc-software.de.
+ * Copyright 2011-2013, Axel Dörfler, axeld@pinc-software.de.
  * Distributed under the terms of the MIT License.
  */
 
@@ -8,6 +8,8 @@
 
 #include <stdlib.h>
 
+#include <UnicodeChar.h>
+
 
 #define TRACE_IMAP
 #ifdef TRACE_IMAP
@@ -53,8 +55,41 @@ RFC3501Encoding::~RFC3501Encoding()
 BString
 RFC3501Encoding::Encode(const BString& clearText) const
 {
-	// TODO!
-	return clearText;
+	const char* clear = clearText.String();
+	bool shifted = false;
+	int32 bitsToWrite = 0;
+	int32 sextet = 0;
+	BString buffer;
+
+	while (true) {
+		uint32 c = BUnicodeChar::FromUTF8(&clear);
+		if (c == 0)
+			break;
+
+		if (!shifted && c == '&')
+			buffer += "&-";
+		else if (c >= 0x20 && c <= 0x7e) {
+			_Unshift(buffer, bitsToWrite, sextet, shifted);
+			buffer += c;
+		} else {
+			// Enter shifted mode, encode in base64
+			if (!shifted) {
+				buffer += '&';
+				shifted = true;
+			}
+
+			bitsToWrite += 16;
+			while (bitsToWrite >= 6) {
+				bitsToWrite -= 6;
+				buffer += kBase64Alphabet[(sextet + (c >> bitsToWrite)) & 0x3f];
+				sextet = 0;
+			}
+			sextet = (c << (6 - bitsToWrite)) & 0x3f;
+		}
+	}
+
+	_Unshift(buffer, bitsToWrite, sextet, shifted);
+	return buffer;
 }
 
 
@@ -69,6 +104,7 @@ RFC3501Encoding::Decode(const BString& encodedText) const
 			if (i < end - 1 && encodedText.ByteAt(i + 1) == '-') {
 				// just add an ampersand
 				buffer += '&';
+				i++;
 			} else {
 				// base64 encoded chunk
 				uint32 value = 0;
@@ -134,6 +170,23 @@ RFC3501Encoding::_ToUTF8(BString& string, uint32 c) const
 }
 
 
+//!	Exit base64, or "shifted" mode.
+void
+RFC3501Encoding::_Unshift(BString& buffer, int32& bitsToWrite, int32& sextet,
+	bool& shifted) const
+{
+	if (!shifted)
+		return;
+
+	if (bitsToWrite != 0)
+		buffer += kBase64Alphabet[sextet];
+	buffer += '-';
+	sextet = 0;
+	bitsToWrite = 0;
+	shifted = false;
+}
+
+
 // #pragma mark -
 
 

src/add-ons/mail_daemon/inbound_protocols/imap/imap_lib/Response.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011, Axel Dörfler, axeld@pinc-software.de.
+ * Copyright 2011-2013, Axel Dörfler, axeld@pinc-software.de.
  * Distributed under the terms of the MIT License.
  */
 #ifndef RESPONSE_H
@@ -30,6 +30,8 @@ public:
 
 private:
 			void				_ToUTF8(BString& string, uint32 c) const;
+			void				_Unshift(BString& string, int32& bitsToWrite,
+									int32& sextet, bool& shifted) const;
 };
 
 

src/tests/add-ons/mail/imap/Jamfile

@@ -33,6 +33,13 @@ SimpleTest imap_tester :
 	: be [ TargetLibstdc++ ] [ TargetLibsupc++ ] bnetapi mail
 ;
 
+SimpleTest rfc3501_encoding_test :
+	rfc3501_encoding_test.cpp
+	$(libSources)
+
+	: be $(TARGET_LIBSTDC++) $(TARGET_LIBSUPC++) bnetapi
+;
+
 SEARCH on [ FGristFiles $(libSources) ]
 	= [ FDirName $(HAIKU_TOP) src add-ons mail_daemon inbound_protocols imap
 		imap_lib ] ;

src/tests/add-ons/mail/imap/rfc3501_encoding_test.cpp

@@ -0,0 +1,39 @@
+/*
+ * Copyright 2013, Axel Dörfler, axeld@pinc-software.de.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "Response.h"
+
+
+void
+assertEquals(const char* expected, const char* result)
+{
+	if (strcmp(expected, result) != 0) {
+		printf("Expected \"%s\", got \"%s\"\n", expected, result);
+		exit(EXIT_FAILURE);
+	}
+}
+
+
+int
+main()
+{
+	const char* samples[] = {
+		"Gelöscht", "Gel&APY-scht",
+		"&äöß", "&-&AOQA9gDf-"
+	};
+
+	IMAP::RFC3501Encoding encoding;
+
+	for (size_t i = 0; i < sizeof(samples) / sizeof(samples[0]); i += 2) {
+		BString encoded = encoding.Encode(samples[i]);
+		assertEquals(samples[i + 1], encoded);
+		BString decoded = encoding.Decode(encoded);
+		assertEquals(samples[i], decoded);
+	}
+}