//add a new header and set its value
internal void InternalAdd(string name, string value)
{
if (MailHeaderInfo.IsSingleton(name))
{
base.Set(name, value);
}
else
{
base.Add(name, value);
}
}
/// <summary>
/// Extract headers from the text stream into the Headers collection of the ReceivedMessage object provided.
/// </summary>
/// <param name="reader">TextReader providing the data stream to be parsed</param>
/// <param name="messageHeaders">Collection of message headers.</param>
/// <param name="rawheaders">Raw text of headers as received from server.</param>
/// <returns>Returns false if no headers were found. Otherwise returns true.</returns>
private static bool LoadHeaders(TextReader reader, NameValueCollection messageHeaders, StringBuilder rawheaders)
{
Debug.WriteLine("LoadHeaders()");
string line = null;
string lastHeaderKey = null;
//multiple values with the same header key will be delimited by semi-colon.
//semi-colon is reserved as a special character for header encoding in RFC 2047, so this should be safe
Dictionary <string, StringBuilder> headersBuilders = new Dictionary <string, StringBuilder>(StringComparer.InvariantCultureIgnoreCase);
Dictionary <string, string[]> headers;
Debug.WriteLine("Raw:");
while (null != (line = reader.ReadLine()))
{
Debug.WriteLine(line);
if (rawheaders != null)
{
rawheaders.AppendLine(line);
}
//headers end with an empty line
if (line == string.Empty || line.Trim() == string.Empty)
{
break;
}
//some agents malform the key: value expression so that there is no space after the colon.
//for example this BlackBerry Message-ID header
//Message-ID:<*****@*****.**>
Regex regex = new Regex(@"^([^:]+):\s?(.*)$");
Match match = regex.Match(line);
//if a line does not contain a colon it is either a continuation of a previous line or an error
if (match.Success)
{
//split header key from RFC 2047 encoded value
string headerkey = match.Groups[1].Value;
string value = match.Groups[2].Value;
if (!headersBuilders.ContainsKey(headerkey))
{
headersBuilders.Add(headerkey, new StringBuilder(value));
}
else
{
headersBuilders[headerkey].AppendFormat("|~|{0}", value);
}
lastHeaderKey = headerkey;
}
else
{
//continuation line should start with whitespace
if (!string.IsNullOrEmpty(lastHeaderKey) && Regex.IsMatch(line, "^\\s"))
{
string h = line.TrimStart('\t', ' ');
headersBuilders[lastHeaderKey].AppendFormat("|~|{0}", h);
}
else //error in message format, skip ahead and attempt to continue parsing
{
lastHeaderKey = null;
continue;
}
}
}
if (headersBuilders.Count == 0)
{
return(false);
}
headers = new Dictionary <string, string[]>(headersBuilders.Count, StringComparer.InvariantCultureIgnoreCase);
foreach (string key in headersBuilders.Keys)
{
List <string> list = new List <string>(headersBuilders[key].ToString().Split(new[] { "|~|" }, StringSplitOptions.RemoveEmptyEntries));
for (int i = 0; i < list.Count; i++)
{
if (string.IsNullOrEmpty(list[i]))
{
list.RemoveAt(i);
}
}
headers.Add(key, list.ToArray());
}
InPlaceDecodeExtendedHeaders(headers);
//add decoded headers to the ReceivedMessage parameter passed in to this method.
/**************************************************************************
* NOTE:
* The NameValueCollction in MailMessage.Headers is actually an internal Type
* called HeaderCollection. HeaderCollection has different behavior for header keys
* that are defined as singleton. MailHeaderMsft.IsSingleton replicates the internal
* test used by HeaderCollection.
*/
Debug.WriteLine("Decoded:");
foreach (string key in headers.Keys)
{
Debug.WriteLine("Key: " + key);
//I believe IsSingleton is meant to indicate that the field should occur only once in the output
//headers when the message is encoded for transport. The side-effect of the implementation is that it doesn't
//allow adding multiple values to a single key in the NameValueCollection.
if (MailHeaderInfo.IsSingleton(key))
{
//HeaderCollection will use Set internally when Add is called
//need to join multiple values into a single string before adding or
//the last value to be added will be the final value and the others will be lost.
//therefore, components need to be combined into a single comma-separated string
//before being added.
string[] v = headers[key];
string value = string.Join(string.Empty, headers[key]);
//HeaderCollection.Add(string,string) throws an undocumented ArgumentException when being passed
//an empty string as a value. This is quite contrary to the behavior documented for NameValueCollection.Add(string,string)
//which explicitly permits null and empty strings to be added.
//the most common cause of this problem is a BCC: field with no value.
if (value != string.Empty)
{
messageHeaders.Add(key, value);
}
}
else
{
for (int i = 0; i < headers[key].Length; i++)
{
if (!string.IsNullOrEmpty(headers[key][i]))
{
Debug.WriteLine(key + ": " + headers[key][i]);
messageHeaders.Add(key, headers[key][i]);
}
}
}
Debug.WriteLine(key + ": " + messageHeaders[key]);
}
return(true);
}
