MalwareMultiScan/MalwareMultiScan.Shared/Attributes/UrlValidationAttribute.cs

using System;
using System.ComponentModel.DataAnnotations;

namespace MalwareMultiScan.Shared.Attributes
{
    public class UrlValidationAttribute : ValidationAttribute
    {
        protected override ValidationResult IsValid(object value, ValidationContext validationContext)
        {
            var uri = (Uri) value;

            if (uri == null || !uri.IsAbsoluteUri || uri.Scheme != "http" && uri.Scheme != "https")
                return new ValidationResult("Only http(s) absolute URLs are supported");

            return ValidationResult.Success;
        }
    }
}