/// <summary>
/// Parses DIGEST-MD5 response from response-string.
/// </summary>
/// <param name="digestResponse">Response string.</param>
/// <returns>Returns DIGEST-MD5 response.</returns>
/// <exception cref="ArgumentNullException">Is raised when <b>digestResponse</b> isnull reference.</exception>
/// <exception cref="ParseException">Is raised when response parsing + validation fails.</exception>
public static AUTH_SASL_DigestMD5_Response Parse(string digestResponse)
{
if(digestResponse == null){
throw new ArgumentNullException(digestResponse);
}
/* RFC 2831 2.1.2.
The client makes note of the "digest-challenge" and then responds
with a string formatted and computed according to the rules for a
"digest-response" defined as follows:
digest-response = 1#( username | realm | nonce | cnonce |
nonce-count | qop | digest-uri | response |
maxbuf | charset | cipher | authzid |
auth-param )
username = "******" "=" <"> username-value <">
username-value = qdstr-val
cnonce = "cnonce" "=" <"> cnonce-value <">
cnonce-value = qdstr-val
nonce-count = "nc" "=" nc-value
nc-value = 8LHEX
qop = "qop" "=" qop-value
digest-uri = "digest-uri" "=" <"> digest-uri-value <">
digest-uri-value = serv-type "/" host [ "/" serv-name ]
serv-type = 1*ALPHA
host = 1*( ALPHA | DIGIT | "-" | "." )
serv-name = host
response = "response" "=" response-value
response-value = 32LHEX
LHEX = "0" | "1" | "2" | "3" |
"4" | "5" | "6" | "7" |
"8" | "9" | "a" | "b" |
"c" | "d" | "e" | "f"
cipher = "cipher" "=" cipher-value
authzid = "authzid" "=" <"> authzid-value <">
authzid-value = qdstr-val
*/
AUTH_SASL_DigestMD5_Response retVal = new AUTH_SASL_DigestMD5_Response();
// Set default values.
retVal.m_Realm = "";
string[] parameters = TextUtils.SplitQuotedString(digestResponse,',');
foreach(string parameter in parameters){
string[] name_value = parameter.Split(new char[]{'='},2);
string name = name_value[0].Trim();
if(name_value.Length == 2){
if(name.ToLower() == "username"){
retVal.m_UserName = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "realm"){
retVal.m_Realm = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "nonce"){
retVal.m_Nonce = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "cnonce"){
retVal.m_Cnonce = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "nc"){
retVal.m_NonceCount = Int32.Parse(TextUtils.UnQuoteString(name_value[1]),System.Globalization.NumberStyles.HexNumber);
}
else if(name.ToLower() == "qop"){
retVal.m_Qop = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "digest-uri"){
retVal.m_DigestUri = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "response"){
retVal.m_Response = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "charset"){
retVal.m_Charset = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "cipher"){
retVal.m_Cipher = TextUtils.UnQuoteString(name_value[1]);
}
else if(name.ToLower() == "authzid"){
retVal.m_Authzid = TextUtils.UnQuoteString(name_value[1]);
}
}
}
/* Validate required fields.
Per RFC 2831 2.1.2. Only [username nonce cnonce nc response] parameters are required.
*/
if(string.IsNullOrEmpty(retVal.UserName)){
throw new ParseException("The response-string doesn't contain required parameter 'username' value.");
}
if(string.IsNullOrEmpty(retVal.Nonce)){
throw new ParseException("The response-string doesn't contain required parameter 'nonce' value.");
}
if(string.IsNullOrEmpty(retVal.Cnonce)){
throw new ParseException("The response-string doesn't contain required parameter 'cnonce' value.");
}
if(retVal.NonceCount < 1){
throw new ParseException("The response-string doesn't contain required parameter 'nc' value.");
}
if(string.IsNullOrEmpty(retVal.Response)){
throw new ParseException("The response-string doesn't contain required parameter 'response' value.");
}
return retVal;
}
/// <summary>
/// Continues authentication process.
/// </summary>
/// <param name="serverResponse">Server sent SASL response.</param>
/// <returns>Returns challange request what must be sent to server or null if authentication has completed.</returns>
/// <exception cref="ArgumentNullException">Is raised when <b>serverResponse</b> is null reference.</exception>
/// <exception cref="InvalidOperationException">Is raised when this method is called when authentication is completed.</exception>
public override byte[] Continue(byte[] serverResponse)
{
if(serverResponse == null){
throw new ArgumentNullException("serverResponse");
}
if(m_IsCompleted){
throw new InvalidOperationException("Authentication is completed.");
}
/* RFC 2831.
The base64-decoded version of the SASL exchange is:
S: realm="elwood.innosoft.com",nonce="OA6MG9tEQGm2hh",qop="auth",
algorithm=md5-sess,charset=utf-8
C: charset=utf-8,username="******",realm="elwood.innosoft.com",
nonce="OA6MG9tEQGm2hh",nc=00000001,cnonce="OA6MHXh6VqTrRk",
digest-uri="imap/elwood.innosoft.com",
response=d388dad90d4bbd760a152321f2143af7,qop=auth
S: rspauth=ea40f60335c427b5527b84dbabcdfffd
C:
S: ok
The password in this example was "secret".
*/
if(m_State == 0){
m_State++;
// Parse server challenge.
AUTH_SASL_DigestMD5_Challenge challenge = AUTH_SASL_DigestMD5_Challenge.Parse(Encoding.UTF8.GetString(serverResponse));
// Construct our response to server challenge.
m_pResponse = new AUTH_SASL_DigestMD5_Response(
challenge,
challenge.Realm[0],
m_UserName,
m_Password,
Guid.NewGuid().ToString().Replace("-",""),
1,
challenge.QopOptions[0],
m_Protocol + "/" + m_ServerName
);
return Encoding.UTF8.GetBytes(m_pResponse.ToResponse());
}
else if(m_State == 1){
m_State++;
m_IsCompleted = true;
// Check rspauth value.
if(!string.Equals(Encoding.UTF8.GetString(serverResponse),m_pResponse.ToRspauthResponse(m_UserName,m_Password),StringComparison.InvariantCultureIgnoreCase)){
throw new Exception("Server server 'rspauth' value mismatch with local 'rspauth' value.");
}
return new byte[0];
}
else{
throw new InvalidOperationException("Authentication is completed.");
}
}