README.md

SafeWebCore – MVC Example

Demonstrates SafeWebCore in a full ASP.NET Core MVC application with Razor Views, typed policy builders, path-based policies, and automatic nonce injection via TagHelpers.

What this example shows

Feature	Where
AddNetSecureHeadersMvcPreset()	Program.cs
report-to + ReportingEndpoints first-class setup	Program.cs
ReferrerPolicyBuilder typed builder	Program.cs
PermissionsPolicyBuilder typed builder	Program.cs
CrossOriginPolicyBuilder typed builder	Program.cs
Path-based policy override (/public → report-only CSP)	Program.cs
[CspNonce] attribute on a controller	Controllers/HomeController.cs
@addTagHelper *, SafeWebCore	Views/_ViewImports.cshtml
Auto-nonce on <script> / <style> via TagHelpers	Views/Home/Index.cshtml, Views/Shared/_Layout.cshtml
Explicit nonce via ViewData["CspNonce"]	Views/Home/Index.cshtml

Running the example

cd examples/MvcApp
dotnet run

Open http://localhost:5000 and inspect the response headers in DevTools → Network.

TagHelper nonce injection

After adding @addTagHelper *, SafeWebCore to _ViewImports.cshtml, every <script> and <style> tag in Razor views automatically receives a nonce="…" attribute — no manual plumbing required.

<!-- In any Razor view — nonce is added automatically -->
<script>
    console.log('Allowed by CSP!');
</script>

<style>
    body { font-family: sans-serif; }
</style>

Path policies

The /public route prefix uses a separate policy with UseCspReportOnly = true. All other routes use the strict enforced CSP from the MVC preset. This lets you roll out tighter policies gradually.

Reporting API rollout

Program.cs demonstrates first-class reporting endpoint configuration for CSP report-to:

opts.Csp = opts.Csp with { ReportTo = "csp-endpoint" };
opts.ReportingEndpoints.Add(new()
{
    Group = "csp-endpoint",
    Url = "https://localhost:5001/csp-report"
});

Combined with UseCspReport(), this gives a complete staged rollout path while staying fully backward compatible.

Typed builders

Use the fluent builders for non-CSP headers instead of raw strings:

opts.PermissionsPolicyValue = new PermissionsPolicyBuilder()
    .Disable(PermissionsFeature.Camera)
    .AllowSelf(PermissionsFeature.Geolocation)
    .Build();