private async Task <bool> isTokenValid(string token)
{
try
{
var item = await context.Tokens.Where(t => t.Value.Equals(token) && t.Expires > DateTime.Now && t.Used == false).FirstOrDefaultAsync();
if (item != null)
{
// update token if valid then return valid
item.Used = true;
int result = context.SaveChanges();
return(Convert.ToBoolean(result));
}
}
catch (System.Exception e)
{
exceptionManager.DoException(e);
}
return(false);
}
/// <summary>
/// generate captcha image
/// </summary>
/// <param name="size">alphanumeric length of the captcha</param>
/// <returns>image properties and image binary data</returns>
private async Task <CaptchaImage> generateCaptcha(int size)
{
try
{
int width = size * 30;
int height = width / 4;
var b = new Bitmap(width, height);
var g = Graphics.FromImage(b);
//create brush and rectangle
var brush = new HatchBrush(HatchStyle.SmallConfetti, Color.LightSteelBlue, Color.White);
g.FillRectangle(brush, 0, 0, b.Width, b.Height);
float emSize = width / size;
var fnt = new Font("Arial", emSize, FontStyle.Italic);
// generate truly random captcha value
string value = generateRandomCaptchaValue(size);
while (string.IsNullOrEmpty(value))
{
value = generateRandomCaptchaValue(size);
}
// write the generated value on the image
g.DrawString(value, fnt, Brushes.Coral, 0, 0, StringFormat.GenericTypographic);
// generate random noise on the image
brush = new HatchBrush(HatchStyle.LargeConfetti, Color.SlateBlue, Color.SlateGray);
fillRandomNoise(g, brush, width, height);
// draw random lines on the image
Point[] iP = getRandomPoints(width, height);
for (int i = 0; i < 3; i++)
{
Brush brs = Brushes.BlueViolet;
if (i % 3 == 1)
{
brs = Brushes.DodgerBlue;
}
if (i % 3 == 2)
{
brs = Brushes.MediumVioletRed;
}
Pen pn = new Pen(brs, 2);
g.DrawBezier(pn, iP[i * 4], iP[i * 4 + 1], iP[i * 4 + 2], iP[i * 4 + 3]);
}
// create image
byte[] bBuffer = (byte[])System.ComponentModel.TypeDescriptor.GetConverter(b).ConvertTo(b, typeof(byte[]));
// add image properties to database
var guid = await saveCaptcha(value);
// return image with properties
if (guid.HasValue)
{
return new CaptchaImage()
{
ID = guid.Value, Value = value, Data = bBuffer, MimeType = "image/jpg"
}
}
;
}
catch (System.Exception e)
{
exceptionManager.DoException(e);
}
return(null);
}