/// <summary>
/// Returns header field parameters as string.
/// </summary>
/// <param name="charset">Charset to use to encode 8-bit characters. Value null means parameters not encoded.</param>
/// <returns>Returns header field parameters as string.</returns>
public string ToString(Encoding charset)
{
/* RFC 2231.
* If parameter conatins 8-bit byte, we need to encode parameter value
* If parameter value length bigger than MIME maximum allowed line length,
* we need split value.
*/
if (charset == null)
{
charset = Encoding.Default;
}
StringBuilder retVal = new StringBuilder();
foreach (MIME_h_Parameter parameter in this.ToArray())
{
if (string.IsNullOrEmpty(parameter.Value))
{
retVal.Append(";\r\n\t" + parameter.Name);
}
// We don't need to encode or split value.
else if ((charset == null || Net_Utils.IsAscii(parameter.Value)) && parameter.Value.Length < 76)
{
retVal.Append(";\r\n\t" + parameter.Name + "=" + TextUtils.QuoteString(parameter.Value));
}
// Use RFC 2047 to encode parameter.
else if (m_EncodeRfc2047)
{
retVal.Append(";\r\n\t" + parameter.Name + "=" + TextUtils.QuoteString(MIME_Encoding_EncodedWord.EncodeS(MIME_EncodedWordEncoding.B, Encoding.UTF8, false, parameter.Value)));
}
// We need to RFC 2231 encode/split value.
else
{
byte[] byteValue = charset.GetBytes(parameter.Value);
List <string> values = new List <string>();
// Do encoding/splitting.
int offset = 0;
char[] valueBuff = new char[50];
foreach (byte b in byteValue)
{
// We need split value as RFC 2231 says.
if (offset >= (50 - 3))
{
values.Add(new string(valueBuff, 0, offset));
offset = 0;
}
// Normal char, we don't need to encode.
if (MIME_Reader.IsAttributeChar((char)b))
{
valueBuff[offset++] = (char)b;
}
// We need to encode byte as %X2.
else
{
valueBuff[offset++] = '%';
valueBuff[offset++] = (b >> 4).ToString("X")[0];
valueBuff[offset++] = (b & 0xF).ToString("X")[0];
}
}
// Add pending buffer value.
if (offset > 0)
{
values.Add(new string(valueBuff, 0, offset));
}
for (int i = 0; i < values.Count; i++)
{
// Only fist value entry has charset and language info.
if (charset != null && i == 0)
{
retVal.Append(";\r\n\t" + parameter.Name + "*" + i.ToString() + "*=" + charset.WebName + "''" + values[i]);
}
else
{
retVal.Append(";\r\n\t" + parameter.Name + "*" + i.ToString() + "*=" + values[i]);
}
}
}
}
return(retVal.ToString());
}
