// Returns the transaction id
internal static string SubmitFactor(string sid, DuoChoice choice, string passcode, RestClient rest)
{
var parameters = new Dictionary <string, object>
{
{ "sid", sid },
{ "device", choice.Device.Id },
{ "factor", GetFactorParameterValue(choice.Factor) },
};
if (!passcode.IsNullOrEmpty())
{
parameters["passcode"] = passcode;
}
var response = PostForm <R.SubmitFactor>("frame/prompt", parameters, rest);
var id = response.TransactionId;
if (id.IsNullOrEmpty())
{
throw MakeInvalidResponseError("Duo: transaction ID (txid) is expected but wasn't found");
}
return(id);
}
// Returns the second factor token from Duo or null when canceled by the user.
public static Result Authenticate(string host, string signature, IDuoUi ui, IRestTransport transport)
{
var rest = new RestClient(transport, $"https://{host}");
var(tx, app) = ParseSignature(signature);
var html = DownloadFrame(tx, rest);
var(sid, devices) = ParseFrame(html);
while (true)
{
// Ask the user to choose what to do
var choice = ui.ChooseDuoFactor(devices);
if (choice == null)
{
return(null); // Canceled by user
}
// SMS is a special case: it doesn't submit any codes, it rather tells the server to send
// a new batch of passcodes to the phone via SMS.
if (choice.Factor == DuoFactor.SendPasscodesBySms)
{
SubmitFactor(sid, choice, "", rest);
choice = new DuoChoice(choice.Device, DuoFactor.Passcode, choice.RememberMe);
}
// Ask for the passcode
var passcode = "";
if (choice.Factor == DuoFactor.Passcode)
{
passcode = ui.ProvideDuoPasscode(choice.Device);
if (passcode.IsNullOrEmpty())
{
return(null); // Canceled by user
}
}
var token = SubmitFactorAndWaitForToken(sid, choice, passcode, ui, rest);
// Flow error like an incorrect passcode. The UI has been updated with the error. Keep going.
if (token.IsNullOrEmpty())
{
continue;
}
// All good
return(new Result($"{token}:{app}", choice.RememberMe));
}
}
// Returns null when a recoverable flow error (like incorrect code or time out) happened
// TODO: Don't return null, use something more obvious
internal static string SubmitFactorAndWaitForToken(string sid,
DuoChoice choice,
string passcode,
IDuoUi ui,
RestClient rest)
{
var txid = SubmitFactor(sid, choice, passcode, rest);
var url = PollForResultUrl(sid, txid, ui, rest);
if (url.IsNullOrEmpty())
{
return(null);
}
return(FetchToken(sid, url, ui, rest));
}
