Allow choosing between encoding modes for parameter values.

3 files changed, 95 insertions, 22 deletions

diff --git a/src/vmime/generationContext.cpp b/src/vmime/generationContext.cpp
index e9662883..0a76f4d0 100644
--- a/src/vmime/generationContext.cpp
+++ b/src/vmime/generationContext.cpp
@@ -32,7 +32,8 @@ generationContext::generationContext()
 	: m_maxLineLength(lineLengthLimits::convenient),
 	  m_prologText("This is a multi-part message in MIME format. Your mail reader " \
 	               "does not understand MIME message format."),
-	  m_epilogText("")
+	  m_epilogText(""),
+	  m_paramValueMode(PARAMETER_VALUE_RFC2231_ONLY)
 {
 }
 
@@ -89,6 +90,19 @@ void generationContext::setEpilogText(const string& epilogText)
 }
 
 
+void generationContext::setEncodedParameterValueMode(const EncodedParameterValueModes mode)
+{
+	m_paramValueMode = mode;
+}
+
+
+generationContext::EncodedParameterValueModes
+	generationContext::getEncodedParameterValueMode() const
+{
+	return m_paramValueMode;
+}
+
+
 generationContext& generationContext::operator=(const generationContext& ctx)
 {
 	copyFrom(ctx);
@@ -103,6 +117,7 @@ void generationContext::copyFrom(const generationContext& ctx)
 	m_maxLineLength = ctx.m_maxLineLength;
 	m_prologText = ctx.m_prologText;
 	m_epilogText = ctx.m_epilogText;
+	m_paramValueMode = ctx.m_paramValueMode;
 }
 
 
diff --git a/src/vmime/generationContext.hpp b/src/vmime/generationContext.hpp
index 949f06ac..22700c90 100644
--- a/src/vmime/generationContext.hpp
+++ b/src/vmime/generationContext.hpp
@@ -82,6 +82,51 @@ public:
 	  */
 	void setEpilogText(const string& epilogText);
 
+	/** Modes available for generating values in parameterized header fields.
+	  */
+	enum EncodedParameterValueModes
+	{
+		PARAMETER_VALUE_NO_ENCODING,          /**< Only generate 7-bit (ASCII-only) values,
+		                                           even if the value contains non-ASCII chars or
+		                                           if folding is needed. */
+		PARAMETER_VALUE_RFC2047_ONLY,         /**< Only generate RFC-2047 values (do not use
+		                                           RFC-2231). This is non-standard but most
+		                                           mail clients support it. */
+		PARAMETER_VALUE_RFC2231_ONLY,         /**< Only generate RFC-2231 values (do not use
+		                                           RFC-2047). Some mail clients may not support
+		                                           it. This is the default. */
+		PARAMETER_VALUE_RFC2231_AND_RFC2047   /**< Generate both RFC-2047- and RFC-2231-encoded
+		                                           values. */
+	};
+
+	/** Sets the mode used for generating parameter values in a parameterized
+	  * header field (see parameterizedHeaderField class).
+	  *
+	  * PARAMETER_VALUE_NO_ENCODING or PARAMETER_VALUE_RFC2047_ONLY
+	  * can be used for compatibility with implementations that do not
+	  * understand RFC-2231, to generate a normal parameter value.
+	  * PARAMETER_VALUE_RFC2047_ONLY is non-standard (and expressly
+	  * prohibited by the RFC) but most mail clients support it.
+	  *
+	  * Notice: if both the normal value and the extended value are present,
+	  * the latter can be ignored by mail processing systems. This may lead
+	  * to annoying problems, for example, with strange names of attachments
+	  * with all but 7-bit ascii characters removed, etc. Either
+	  * PARAMETER_VALUE_RFC2231_ONLY or PARAMETER_VALUE_RFC2047_ONLY should
+	  * be preferred over PARAMETER_VALUE_RFC2231_AND_RFC2047, not to create
+	  * a normal value if the extended value is to be generated.
+	  *
+	  * @param mode parameter value generation mode
+	  */
+	void setEncodedParameterValueMode(const EncodedParameterValueModes mode);
+
+	/** Returns the mode used for generating parameter values in a parameterized
+	  * header field (see parameterizedHeaderField class).
+	  *
+	  * @return parameter value generation mode
+	  */
+	EncodedParameterValueModes getEncodedParameterValueMode() const;
+
 	/** Returns the default context used for generating messages.
 	  *
 	  * @return a reference to the default generation context
@@ -97,6 +142,8 @@ protected:
 
 	string m_prologText;
 	string m_epilogText;
+
+	EncodedParameterValueModes m_paramValueMode;
 };
 
 
diff --git a/src/vmime/parameter.cpp b/src/vmime/parameter.cpp
index b8d5b36e..45e68ad6 100644
--- a/src/vmime/parameter.cpp
+++ b/src/vmime/parameter.cpp
@@ -279,7 +279,13 @@ void parameter::generateImpl
 	const string& value = m_value->getBuffer();
 
 	// For compatibility with implementations that do not understand RFC-2231,
-	// also generate a normal "7bit/us-ascii" parameter
+	// we may also generate a normal "7bit/us-ascii" parameter
+	generationContext::EncodedParameterValueModes
+		genMode = ctx.getEncodedParameterValueMode();
+
+#if VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
+	genMode = generationContext::PARAMETER_VALUE_RFC2231_AND_RFC2047;
+#endif
 
 	// [By Eugene A. Shatokhin]
 	// Note that if both the normal "7bit/us-ascii" value and the extended
@@ -366,7 +372,8 @@ void parameter::generateImpl
 	const bool alwaysEncode = m_value->getCharset().getRecommendedEncoding(recommendedEnc);
 	bool extended = alwaysEncode;
 
-	if (needQuotedPrintable)
+	if ((needQuotedPrintable || cutValue) &&
+	    genMode != generationContext::PARAMETER_VALUE_NO_ENCODING)
 	{
 		// Send the name in quoted-printable, so outlook express et.al.
 		// will understand the real filename
@@ -378,7 +385,8 @@ void parameter::generateImpl
 	else
 	{
 		// Do not chop off this value, but just add the complete name as one header line.
-		for (size_t i = 0 ; i < value.length() ; ++i)
+		for (size_t i = 0, n = value.length(), curValueLength = 0 ;
+		     i < n && curValueLength < valueLength ; ++i)
 		{
 			const char_t c = value[i];
 
@@ -391,6 +399,7 @@ void parameter::generateImpl
 			{
 				sevenBitStream << value[i];
 				++pos;
+				++curValueLength;
 			}
 			else
 			{
@@ -406,26 +415,29 @@ void parameter::generateImpl
 		++pos;
 	}
 
-#if VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
-	os << sevenBitBuffer;
-#endif // !VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
+	if (genMode == generationContext::PARAMETER_VALUE_RFC2047_ONLY ||
+	    genMode == generationContext::PARAMETER_VALUE_RFC2231_AND_RFC2047)
+	{
+		os << sevenBitBuffer;
+	}
 
 	// Also generate an extended parameter if the value contains 8-bit characters
 	// or is too long for a single line
-	if (extended || cutValue)
+	if ((extended || cutValue) &&
+		genMode != generationContext::PARAMETER_VALUE_NO_ENCODING &&
+	    genMode != generationContext::PARAMETER_VALUE_RFC2047_ONLY)
 	{
 
-#if VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
-
-		os << ';';
-		++pos;
-
-#else // !VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
-
-		// The data output to 'sevenBitBuffer' will be discarded in this case
-		pos = curLinePos;
-
-#endif // VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
+		if (genMode == generationContext::PARAMETER_VALUE_RFC2231_AND_RFC2047)
+		{
+			os << ';';
+			++pos;
+		}
+		else
+		{
+			// The data output to 'sevenBitBuffer' will be discarded in this case
+			pos = curLinePos;
+		}
 
 		/* RFC-2231
 		 * ========
@@ -572,8 +584,8 @@ void parameter::generateImpl
 			}
 		}
 	}
-#if !VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
-	else
+	else if (!(genMode == generationContext::PARAMETER_VALUE_RFC2047_ONLY ||
+	           genMode == generationContext::PARAMETER_VALUE_RFC2231_AND_RFC2047))
 	{
 		// The value does not contain 8-bit characters and
 		// is short enough for a single line.
@@ -582,7 +594,6 @@ void parameter::generateImpl
 		// Output what has been stored in temporary buffer so far
 		os << sevenBitBuffer;
 	}
-#endif // !VMIME_ALWAYS_GENERATE_7BIT_PARAMETER
 
 	if (newLinePos)
 		*newLinePos = pos;