protected override TSyncChallengeResult Challenge(
ref SASLChallengeArguments args,
SASLCredentialsSCRAMForClient credentials
)
{
var prevState = this._state;
var challengeResult = SASLChallengeResult.MoreToCome;
var writeOffset = args.WriteOffset;
Int32 errorCode;
Int32 nextState;
if (credentials == null)
{
errorCode = SCRAMCommon.ERROR_CLIENT_SUPPLIED_WITH_INVALID_CREDENTIALS;
nextState = -1;
}
else
{
switch (prevState)
{
case STATE_INITIAL:
errorCode = this.PerformInitial(ref args, credentials, ref writeOffset);
nextState = STATE_FINAL;
break;
case STATE_FINAL:
// Read server response and write our response
errorCode = this.PerformFinal(ref args, credentials, ref writeOffset);
nextState = STATE_VALIDATE;
break;
case STATE_VALIDATE:
errorCode = this.PerformValidate(ref args, credentials);
nextState = STATE_COMPLETED;
challengeResult = SASLChallengeResult.Completed;
break;
default:
nextState = -1;
errorCode = SCRAMCommon.ERROR_INVALID_STATE;
break;
}
}
TSyncChallengeResult retVal;
if (errorCode != 0 ||
nextState < 0 ||
Interlocked.CompareExchange(ref this._state, nextState, prevState) != prevState)
{
retVal = new TSyncChallengeResult(errorCode == 0 ? SCRAMCommon.ERROR_CONCURRENT_ACCESS : errorCode);
}
else
{
retVal = new TSyncChallengeResult((writeOffset - args.WriteOffset, challengeResult));
}
return(retVal);
}
private Int32 PerformInitial(
ref SASLChallengeArguments args,
SASLCredentialsSCRAMForClient credentials,
ref Int32 writeOffset
)
{
var encoding = args.Encoding;
var array = args.WriteArray;
// Write "n,,n=<username>,r=<client nonce>
// Write "n,,n="
array.CurrentMaxCapacity = encoding.Encoding.GetByteCount(SCRAMCommon.CLIENT_FIRST_PREFIX_1 + SCRAMCommon.CLIENT_FIRST_PREFIX_2);
encoding.WriteString(array.Array, ref writeOffset, SCRAMCommon.CLIENT_FIRST_PREFIX_1);
var messageStart = writeOffset;
encoding.WriteString(array.Array, ref writeOffset, SCRAMCommon.CLIENT_FIRST_PREFIX_2);
// Write processed and escaped username
SASLUtility.WriteString(
credentials.Username,
encoding,
array,
ref writeOffset,
normalizer: (name, nameIdx) =>
{
// Escape the ',' and '=' characters, since they are reserved.
switch (name[nameIdx])
{
case ',':
return(SCRAMCommon.COMMA_ESCAPE);
case '=':
return(SCRAMCommon.EQUALS_ESCAPE);
default:
return(default);
}
