ASP.Net Core 3.1 Identity - Generating Password Reset Token Issue

Question

I am developing a site where the users will be able to click a "Forgot My Password" button to reset their passwords.

Currently, once the email has been validated, the following code should generate a token to be emailed to the user:

if(validUser != null)
        {
            var generationTime = DateTime.Now;
            var pwToken = await _userManager.GeneratePasswordResetTokenAsync(validUser);
            await _userManager.UpdateAsync(validUser);

            var url = $"https://{Request.Host}/verify/{HttpUtility.UrlEncode(pwToken)}";

            //EmailHelper.SendMagicLinkEmail(validUser, url, Request);

            return new RedirectResult("/");
        }

All information online regarding this seems to suggest that this is the way to do things. I have set up the Default token providers in the Startup.csfile too:

identityOptions: o => {
                    o.User.RequireUniqueEmail = true;
                    o.Tokens.PasswordResetTokenProvider = TokenOptions.DefaultProvider;
                    o.Tokens.EmailConfirmationTokenProvider = TokenOptions.DefaultProvider;
                    
                },

Yet when a token is generated it produces a large token such as this:

CfDJ8CnvAYtZf+1IjXpKUM7+umDYEaImg2SPFglPX3Y8RmYpEfg5zpK8xL54lvlbJUd54CaIzzYlff/GU+xKKS8mmG5UdC1zdk24nOsJNpIlmC3P5V72BchS4P9DGFTR77XiKbMAAYymnMomS2zCdTKh+E4bn9RI6FVinMecG1HR7nSHmOI2McbXHBFTanI/0uwxH5WI/Dj4AFTBP39ni7mfKkeWz2nJ5pTemELJJ6pYP50+

The problem here is obviously the forward slashes, which cause issues with routing so are encoded out here:

var url = $"https://{Request.Host}/verify/{HttpUtility.UrlEncode(pwToken)}";

The problem is that even with that, .Net Core seems to un-encode it and produce the following error when the generated link is accessed:

This error isn't necessarily the issue, and I do understand it's importance. Yet I can't seem to find any explanation as to why this token is behaving this way. All online examples seem to produce a fairly standard GUID style token, not something such as this.

Does anyone know why this might be happening?

Cheers

coolhand · Accepted Answer · 2021-02-24T20:36:14.153

You may want to try the Url.Action() method:

Example:

    var token = userManager.GeneratePasswordResetTokenAsync(user).Result;
    var resetLink = Url.Action("ResetPassword","Account", new { token = token }, protocol: HttpContext.Request.Scheme);
    var message = "<a href=\"" + resetLink + "\">Click here to reset your password</a>";
    //Then send your message to the user

Note in the example above the email must be HTML for the link to work

score 2 · Answer 2 · answered Feb 24 '21 at 18:22

The token looks fairly normal to me.

I think the URL encoding method you'd want to use is Uri.EscapeDataString. What I've personally done is using a UriBuilder and escaped the query string values (in this case for email confirmation):

var uriBuilder = new UriBuilder
{
    Scheme = "https",
    Host = "my.website.com",
    Path = "/confirmEmail",
    Query = $"email={Uri.EscapeDataString(email)}&token={Uri.EscapeDataString(token)}"
};

var fullUrl = uriBuilder.Uri.AbsoluteUri;

For you that'd be:

var uriBuilder = new UriBuilder
{
    Scheme = "https",
    Host = Request.Host,
    Path = $"/verify/{Uri.EscapeDataString(pwToken)}"
};

var fullUrl = uriBuilder.Uri.AbsoluteUri;

Thank you for your comment, I had completely forgotten about URIBuilder. Unfortunately, I arrive at the same error, it still seems to be decoding the escaped string for some reason. — Quasimodo, Feb 24 '21 at 19:37

ASP.Net Core 3.1 Identity - Generating Password Reset Token Issue

2 Answers2