Bassinet is a set of 11 utility middlewares to help secure HTTP headers. It's based on the widely used helmet.js. Includes middleware functions for setting the following headers:

• X-XSS-Protection
• Strict-Transport-Security
• Referrer-Policy
• X-Permitted-Cross-Domain-Policies
• X-Download-Options
• X-Powered-By
• X-Frame-Options
• Expect-CT
• X-Content-Type-Options
• X-DNS-Prefetch-Control
• Content-Security-Policy

Initialize the middleware with the desired options —if any— and handle the returned error.

referrerPolicy, err := bassinet.ReferrerPolicy([]{
	bassinet.PolicyOrigin,
	bassinet.PolicyUnsafeURL,
})
if err != nil {
    // handle error
}

To use bassinet with the builtin ServeMux you just wrap it with the initialized middleware.

mux := http.NewServeMux()
mux.HandleFunc("/", home)
srv := http.Server{
	Handler: referrerPolicy(mux)
}

As you might probably want to chain several of the middlewares it is recommended to use a composing function.

xssFilter, err := bassinet.XSSFilter()
if err != nil {
    // handle error
}
htsts, err := bassinet.StrictTransportSecurity(StrictTransportOption{
	maxAge:            60,
  excludeSubdomains: true,
})
if err != nil {
	// handle error
}

middleware := alice.New(xssFilter, htsts)

XSSFilter sets X-XSS-Protection header to 0 to prevent attackers from blocking legit code or inferring information. Read more. XSSFilter accepts no options.

xssFilter, err := bassinet.XSSFilter()
if err != nil {
	// Handle error
}

srv := http.Server{
	Handler: xssFilter(mux)
}

StrictTransportSecurity sets Strict-Transport-Security so that browsers remember if HTTPS is available, to avoid insecure connection before redirect. Read more.

It accepts a bassinet.StrictTransportOptions struct to set the following directives:

• maxAge: Time (in seconds) that the browser should remember if the site has HTTPS. Defaults to 180 days. int
• excludeSubdomains: Optional. If set the browser will apply directive to subdomains. bool
• preload: Optional. If set the browser will check the Preloading Strict Transport Security public list, enabling STS also on first load. bool

policies := bassinet.StrictTransportOptions{
	maxAge:            60 * 60 * 24 * 7, // recheck every week
	excludeSubdomains: true,
	preload: true,
}

sts, err := bassinet.StrictTransportSecurity(policies)
if err != nil {
	// Handle error
}

srv := http.Server{
	Handler: sts(mux)
}

PermittedCrossDomainPolicies sets X-Permitted-Cross-Domain-Policies header to tell some user-agents (most notably Adobe products) your domain's policy for loading cross-domain content. Read more.

Accepts the following policies:

• PCDPNone: No crossdomain.xml file is allowed.
• PCDPMasterOnly: Only check crossdomain.xml in the root directory of the website.
• PCDPByContentType: Only accept files with type text/x-cross-domain-policy.
• PCDPAll: Allow any crossdomain.xml files.

permittedCrossDomainPolicies, err := bassinet.PermittedCrossDomainPolicies(bassinet.PCDPByContentType)
if err != nil {
	// Handle error
}

srv := http.Server{
	Handler: permittedCrossDomainPolicies(mux)
}

IeNoOpen sets X-Download-Options to noopen to prevent IE users to execute downloads in your site's context. Read more.

ieNoOpen := bassinet.IeNoOpen()

srv := http.Server{
	Handler: ieNoOpen(mux)
}