Password Resetting in Servicestack

PasswordResetService.cs

using CORE.Kernel.ExtensionMethods;
using CORE.Models;
using ServiceStack.Common;
using ServiceStack.Common.Web;
using ServiceStack.FluentValidation;
using ServiceStack.ServiceHost;
using ServiceStack.ServiceInterface;
using ServiceStack.ServiceInterface.Auth;
using ServiceStack.ServiceInterface.ServiceModel;
using ServiceStack.ServiceInterface.Validation;
using ServiceStack.WebHost.Endpoints;
using System;
using System.Collections.Generic;
using System.Runtime.Serialization;
using Validation;

namespace CORE
{
    [Route("/passwordreset")]
    [Route("/api/auth/passwordreset")]
    public class PasswordResetRequest
    {
        public string Email { get; set; }

        public string Id { get; set; }

        public string newpassword { get; set; }
    }

    public class passwordResetResponse
    {
        public string id { get; set; }

        public bool passwordChanged { get; set; }

        public bool valid { get; set; }
    }

    [DefaultRequest(typeof(PasswordResetRequest))]
    internal class PasswordResetService : AppServiceBase
    {
        public IUserAuthRepository UserAuthRepo { get; set; }

        //Called when a password reset link is clicked.
        public object Get(PasswordResetRequest request)
        {
            if (!ValidationLibrary.validate(request.Id, ValidationLibrary.GUID))
                return new passwordResetResponse() { valid = false };

            //Display Change Password Screen
            var resetrequest = Cache.Get<PasswordResetRequest>(request.Id);

            var response = new passwordResetResponse();
            response.valid = !(resetrequest == null);
            response.id = request.Id;

            return response;
        }

        //Called when the password request is initiated.
        public string Post(PasswordResetRequest request)
        {
            if (request.Email == null)
            {
                this.Response.StatusCode = 400;
                return "You must provide an email address.";
            }

            if (UserAuthRepo.GetUserAuthByUserName(request.Email) == null)
            {
                this.Response.StatusCode = 400;
                return "Email Address not registered.";
            }

            request.Id = Guid.NewGuid().ToString();

            Cache.Add<PasswordResetRequest>(request.Id, request, new TimeSpan(1, 0, 0));
            var email = new Email();
            email.to = new List<EmailAddress>();
            email.to.Add(new EmailAddress() { email = request.Email });
            email.from = new EmailAddress() { email = "core@cornwall.ac.uk" };
            email.subject = "Password Reset";
            email.body = "<p>Uh Oh!  Have you forgotten your password?</p><p>Somebody asked for a password reminder, if it was you click this link to reset it now.</p><p><a href=\""+AppConfig.getAppConfig().appURL+"/passwordreset?id=" + request.Id + "\">"+AppConfig.getAppConfig().appURL+"/passwordreset?id=" + request.Id + "</a></p><p>This link is valid for 1 hour</p><p>If you've remember your password, or you didn't request a reset, you can ignore this email</p><p>Regards</p><p>Cornwall College</p>";
            email.TrackingId = request.Id;

            PublishMessage<Email>(email);

            return "An email has been sent with a link to reset your password.";
        }

        public passwordResetResponse Put(PasswordResetRequest request)
        {
            if (!ValidationLibrary.validate(request.Id, ValidationLibrary.GUID))
                return new passwordResetResponse() { valid = false };

            if (!ValidationLibrary.validate(request.newpassword, ValidationLibrary.UserPassword))
                return new passwordResetResponse() { valid = false };

            //Changes the password
            var resetrequest = Cache.Get<PasswordResetRequest>(request.Id);

            var response = new passwordResetResponse();
            if (resetrequest == null)
            {
                response.valid = false;
                return response;
            }
            else
            {
                response.valid = true;
            }

            var existingUser = UserAuthRepo.GetUserAuthByUserName(resetrequest.Email);
            if (existingUser == null)
            {
                return new passwordResetResponse() { valid = false };
            }

            UserAuthRepo.UpdateUserAuth(existingUser, existingUser, request.newpassword);

            response.passwordChanged = true;
            Cache.Remove(resetrequest.Id);
            return response;
        }
    }
}

There is a security issue here!

Line 103 should be:
if (resetrequest == null || resetrequest.Email != request.Email)

otherwise it is possible to ask a password reset from one user and then reset the password of another user. Nice!

Just my 2 pence: Further to this, on Line 69-71, I wouldn't return an error if it's an unknown email address as this leaves you open to brute force "find a valid email address" attacks - return should be a success and on the client give a message like "If you're a valid user you'll receive an email..."

Thanks for idea of using cache to store reset request