public void Authenticate(string userName,string password)
{
if(this.IsDisposed){
throw new ObjectDisposedException(this.GetType().Name);
}
if(!this.IsConnected){
throw new InvalidOperationException("You must connect first.");
}
if(this.IsAuthenticated){
throw new InvalidOperationException("Session is already authenticated.");
}
if(string.IsNullOrEmpty(userName)){
throw new ArgumentNullException("userName");
}
if(password == null){
password = "";
}
// Choose authentication method, we consider LOGIN as default.
string authMethod = "LOGIN";
List<string> authMethods = new List<string>(this.SaslAuthMethods);
if(authMethods.Contains("DIGEST-MD5")){
authMethod = "DIGEST-MD5";
}
else if(authMethods.Contains("CRAM-MD5")){
authMethod = "CRAM-MD5";
}
#region AUTH LOGIN
if(authMethod == "LOGIN"){
/* LOGIN
Example:
C: AUTH LOGIN<CRLF>
S: 334 VXNlcm5hbWU6<CRLF> VXNlcm5hbWU6 = base64("USERNAME")
C: base64(username)<CRLF>
S: 334 UGFzc3dvcmQ6<CRLF> UGFzc3dvcmQ6 = base64("PASSWORD")
C: base64(password)<CRLF>
S: 235 Ok<CRLF>
*/
WriteLine("AUTH LOGIN");
// Read server response.
string line = ReadLine();
// Response line must start with 334 or otherwise it's error response.
if(!line.StartsWith("334")){
throw new SMTP_ClientException(line);
}
// Send user name to server.
WriteLine(Convert.ToBase64String(Encoding.ASCII.GetBytes(userName)));
// Read server response.
line = ReadLine();
// Response line must start with 334 or otherwise it's error response.
if(!line.StartsWith("334")){
throw new SMTP_ClientException(line);
}
// Send password to server.
WriteLine(Convert.ToBase64String(Encoding.ASCII.GetBytes(password)));
// Read server response.
line = ReadLine();
// Response line must start with 334 or otherwise it's error response.
if(!line.StartsWith("235")){
throw new SMTP_ClientException(line);
}
m_pAuthdUserIdentity = new GenericIdentity(userName,"LOGIN");
}
#endregion
#region AUTH CRAM-MD5
else if(authMethod == "CRAM-MD5"){
/* CRAM-M5
Description:
HMACMD5 key is "password".
Example:
C: AUTH CRAM-MD5<CRLF>
S: 334 base64(md5_calculation_hash)<CRLF>
C: base64(username password_hash)<CRLF>
S: 235 Ok<CRLF>
*/
WriteLine("AUTH CRAM-MD5");
// Read server response.
string line = ReadLine();
// Response line must start with 334 or otherwise it's error response.
if(!line.StartsWith("334")){
throw new SMTP_ClientException(line);
}
HMACMD5 kMd5 = new HMACMD5(Encoding.ASCII.GetBytes(password));
string passwordHash = Net_Utils.ToHex(kMd5.ComputeHash(Convert.FromBase64String(line.Split(' ')[1]))).ToLower();
// Send authentication info to server.
WriteLine(Convert.ToBase64String(Encoding.ASCII.GetBytes(userName + " " + passwordHash)));
// Read server response.
line = ReadLine();
// Response line must start with 235 or otherwise it's error response
if(!line.StartsWith("235")){
throw new SMTP_ClientException(line);
}
m_pAuthdUserIdentity = new GenericIdentity(userName,"CRAM-MD5");
}
#endregion
#region AUTH DIGEST-MD5
else if(authMethod == "DIGEST-MD5"){
/*
Example:
C: AUTH DIGEST-MD5<CRLF>
S: 334 base64(digestChallange)<CRLF>
C: base64(digestResponse)<CRLF>
S: 334 base64(serverDigestRpAuth)<CRLF>
C: <CRLF>
S: 235 Ok<CRLF>
*/
WriteLine("AUTH DIGEST-MD5");
// Read server response.
string line = ReadLine();
// Response line must start with 334 or otherwise it's error response.
if(!line.StartsWith("334")){
throw new SMTP_ClientException(line);
}
// Parse server challenge.
AUTH_SASL_DigestMD5_Challenge challenge = AUTH_SASL_DigestMD5_Challenge.Parse(Encoding.Default.GetString(Convert.FromBase64String(line.Split(' ')[1])));
// Construct our response to server challenge.
AUTH_SASL_DigestMD5_Response response = new AUTH_SASL_DigestMD5_Response(
challenge,
challenge.Realm[0],
userName,
password,Guid.NewGuid().ToString().Replace("-",""),
1,
challenge.QopOptions[0],
"smtp/" + this.RemoteEndPoint.Address.ToString()
);
// Send authentication info to server.
WriteLine(Convert.ToBase64String(Encoding.Default.GetBytes(response.ToResponse())));
// Read server response.
line = ReadLine();
// Response line must start with 334 or otherwise it's error response.
if(!line.StartsWith("334")){
throw new SMTP_ClientException(line);
}
// Check rspauth value.
if(!string.Equals(Encoding.Default.GetString(Convert.FromBase64String(line.Split(' ')[1])),response.ToRspauthResponse(userName,password),StringComparison.InvariantCultureIgnoreCase)){
throw new Exception("SMTP server 'rspauth' value mismatch.");
}
// Send empty line.
WriteLine("");
// Read server response.
line = ReadLine();
// Response line must start with 235 or otherwise it's error response.
if(!line.StartsWith("235")){
throw new SMTP_ClientException(line);
}
m_pAuthdUserIdentity = new GenericIdentity(userName,"DIGEST-MD5");
}
#endregion
}
