igaisin/secure

HTTP middleware for Go that facilitates some quick security wins.

Secure

Secure is an HTTP middleware for Go that facilitates some quick security wins. It's a standard net/http Handler, and can be used with many frameworks or directly with Go's net/http package.

Usage

// main.go
package main

import (
    "net/http"

    "github.com/unrolled/secure"
)

var myHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("hello world"))
})

func main() {
    secureMiddleware := secure.New(secure.Options{
        AllowedHosts:          []string{"example\\.com", ".*\\.example\\.com"},
        AllowedHostsAreRegex:  true,
        HostsProxyHeaders:     []string{"X-Forwarded-Host"},
        SSLRedirect:           true,
        SSLHost:               "ssl.example.com",
        SSLProxyHeaders:       map[string]string{"X-Forwarded-Proto": "https"},
        STSSeconds:            31536000,
        STSIncludeSubdomains:  true,
        STSPreload:            true,
        FrameDeny:             true,
        ContentTypeNosniff:    true,
        BrowserXssFilter:      true,
        ContentSecurityPolicy: "script-src $NONCE",
    })

    app := secureMiddleware.Handler(myHandler)
    http.ListenAndServe("127.0.0.1:3000", app)
}

Be sure to include the Secure middleware as close to the top (beginning) as possible (but after logging and recovery). It's best to do the allowed hosts and SSL check before anything else.

The above example will only allow requests with a host name of 'example.com', or 'ssl.example.com'. Also if the request is not HTTPS, it will be redirected to HTTPS with the host name of 'ssl.example.com'. Once those requirements are satisfied, it will add the following headers:

Strict-Transport-Security: 31536000; includeSubdomains; preload
X-Frame-Options: DENY
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Content-Security-Policy: script-src 'nonce-a2ZobGFoZg=='

Set the IsDevelopment option to true when developing!

When IsDevelopment is true, the AllowedHosts, SSLRedirect, STS header, and HPKP header will not be in effect. This allows you to work in development/test mode and not have any annoying redirects to HTTPS (ie. development can happen on HTTP), or block localhost has a bad host.

Available options

Secure comes with a variety of configuration options (Note: these are not the default option values. See the defaults below.):

// ...
s := secure.New(secure.Options{
    AllowedHosts: []string{"ssl.example.com"}, // AllowedHosts is a list of fully qualified domain names that are allowed. Default is empty list, which allows any and all host names.
    AllowedHostsAreRegex: false,  // AllowedHostsAreRegex determines, if the provided AllowedHosts slice contains valid regular expressions. Default is false.
    AllowRequestFunc: nil, // AllowRequestFunc is a custom function type that allows you to determine if the request should proceed or not based on your own custom logic. Default is nil.
    HostsProxyHeaders: []string{"X-Forwarded-Hosts"}, // HostsProxyHeaders is a set of header keys that may hold a proxied hostname value for the request.
    SSLRedirect: true, // If SSLRedirect is set to true, then only allow HTTPS requests. Default is false.
    SSLTemporaryRedirect: false, // If SSLTemporaryRedirect is true, the a 302 will be used while redirecting. Default is false (301).
    SSLHost: "ssl.example.com", // SSLHost is the host name that is used to redirect HTTP requests to HTTPS. Default is "", which indicates to use the same host.
    SSLHostFunc: nil, // SSLHostFunc is a function pointer, the return value of the function is the host name that has same functionality as `SSHost`. Default is nil. If SSLHostFunc is nil, the `SSLHost` option will be used.
    SSLProxyHeaders: map[string]string{"X-Forwarded-Proto": "https"}, // SSLProxyHeaders is set of header keys with associated values that would indicate a valid HTTPS request. Useful when using Nginx: `map[string]string{"X-Forwarded-Proto": "https"}`. Default is blank map.
    STSSeconds: 31536000, // STSSeconds is the max-age of the Strict-Transport-Security header. Default is 0, which would NOT include the header.
    STSIncludeSubdomains: true, // If STSIncludeSubdomains is set to true, the `includeSubdomains` will be appended to the Strict-Transport-Security header. Default is false.
    STSPreload: true, // If STSPreload is set to true, the `preload` flag will be appended to the Strict-Transport-Security header. Default is false.
    ForceSTSHeader: false, // STS header is only included when the connection is HTTPS. If you want to force it to always be added, set to true. `IsDevelopment` still overrides this. Default is false.
    FrameDeny: true, // If FrameDeny is set to true, adds the X-Frame-Options header with the value of `DENY`. Default is false.
    CustomFrameOptionsValue: "SAMEORIGIN", // CustomFrameOptionsValue allows the X-Frame-Options header value to be set with a custom value. This overrides the FrameDeny option. Default is "".
    ContentTypeNosniff: true, // If ContentTypeNosniff is true, adds the X-Content-Type-Options header with the value `nosniff`. Default is false.
    BrowserXssFilter: true, // If BrowserXssFilter is true, adds the X-XSS-Protection header with the value `1; mode=block`. Default is false.
    CustomBrowserXssValue: "1; report=https://example.com/xss-report", // CustomBrowserXssValue allows the X-XSS-Protection header value to be set with a custom value. This overrides the BrowserXssFilter option. Default is "".
    ContentSecurityPolicy: "default-src 'self'", // ContentSecurityPolicy allows the Content-Security-Policy header value to be set with a custom value. Default is "". Passing a template string will replace `$NONCE` with a dynamic nonce value of 16 bytes for each request which can be later retrieved using the Nonce function.
    PublicKey: `pin-sha256="base64+primary=="; pin-sha256="base64+backup=="; max-age=5184000; includeSubdomains; report-uri="https://www.example.com/hpkp-report"`, // Deprecated: This feature is no longer recommended. PublicKey implements HPKP to prevent MITM attacks with forged certificates. Default is "".
    ReferrerPolicy: "same-origin", // ReferrerPolicy allows the Referrer-Policy header with the value to be set with a custom value. Default is "".
    FeaturePolicy: "vibrate 'none';", // Deprecated: this header has been renamed to PermissionsPolicy. FeaturePolicy allows the Feature-Policy header with the value to be set with a custom value. Default is "".
    PermissionsPolicy: "fullscreen=(), geolocation=()", // PermissionsPolicy allows the Permissions-Policy header with the value to be set with a custom value. Default is "".
    CrossOriginOpenerPolicy: "same-origin", // CrossOriginOpenerPolicy allows the Cross-Origin-Opener-Policy header with the value to be set with a custom value. Default is "".
    ExpectCTHeader: `enforce, max-age=30, report-uri="https://www.example.com/ct-report"`,

    IsDevelopment: true, // This will cause the AllowedHosts, SSLRedirect, and STSSeconds/STSIncludeSubdomains options to be ignored during development. When deploying to production, be sure to set this to false.
})
// ...

Default options

These are the preset options for Secure:

s := secure.New()

// Is the same as the default configuration options:

l := secure.New(secure.Options{
    AllowedHosts: []string,
    AllowedHostsAreRegex: false,
    AllowRequestFunc: nil,
    HostsProxyHeaders: []string,
    SSLRedirect: false,
    SSLTemporaryRedirect: false,
    SSLHost: "",
    SSLProxyHeaders: map[string]string{},
    STSSeconds: 0,
    STSIncludeSubdomains: false,
    STSPreload: false,
    ForceSTSHeader: false,
    FrameDeny: false,
    CustomFrameOptionsValue: "",
    ContentTypeNosniff: false,
    BrowserXssFilter: false,
    ContentSecurityPolicy: "",
    PublicKey: "",
    ReferrerPolicy: "",
    FeaturePolicy: "",
    PermissionsPolicy: "",
    CrossOriginOpenerPolicy: "",
    ExpectCTHeader: "",
    IsDevelopment: false,
})

The default bad host handler returns the following error:

http.Error(w, "Bad Host", http.StatusInternalServerError)

Call secure.SetBadHostHandler to set your own custom handler.

The default bad request handler returns the following error:

http.Error(w, "Bad Request", http.StatusBadRequest)

Call secure.SetBadRequestHandler to set your own custom handler.

Allow Request Function

Secure allows you to set a custom function (func(r *http.Request) bool) for the AllowRequestFunc option. You can use this function as a custom filter to allow the request to continue or simply reject it. This can be handy if you need to do any dynamic filtering on any of the request properties. It should be noted that this function will be called on every request, so be sure to make your checks quick and not relying on time consuming external calls (or you will be slowing down all requests). See above on how to set a custom handler for the rejected requests.

Redirecting HTTP to HTTPS

If you want to redirect all HTTP requests to HTTPS, you can use the following example.

// main.go
package main

import (
    "log"
    "net/http"

    "github.com/unrolled/secure"
)

var myHandler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
    w.Write([]byte("hello world"))
})

func main() {
    secureMiddleware := secure.New(secure.Options{
        SSLRedirect: true,
        SSLHost:     "localhost:8443", // This is optional in production. The default behavior is to just redirect the request to the HTTPS protocol. Example: http://github.com/some_page would be redirected to https://github.com/some_page.
    })

    app := secureMiddleware.Handler(myHandler)

    // HTTP
    go func() {
        log.Fatal(http.ListenAndServe(":8080", app))
    }()

    // HTTPS
    // To generate a development cert and key, run the following from your *nix terminal:
    // go run $GOROOT/src/crypto/tls/generate_cert.go --host="localhost"
    log.Fatal(http.ListenAndServeTLS(":8443", "cert.pem", "key.pem", app))
}

Strict Transport Security

The STS header will only be sent on verified HTTPS connections (and when IsDevelopment is false). Be sure to set the SSLProxyHeaders option if your application is behind a proxy to ensure the proper behavior. If you need the STS header for all HTTP and HTTPS requests (which you shouldn't), you can use the ForceSTSHeader option. Note that if IsDevelopment is true, it will still disable this header even when ForceSTSHeader is set to true.

• The preload flag is required for domain inclusion in Chrome's preload list.

Content Security Policy

You can utilize the CSP Builder to create your policies:

import (
	"github.com/unrolled/secure"
	"github.com/unrolled/secure/cspbuilder"
)

cspBuilder := cspbuilder.Builder{
	Directives: map[string][]string{
		cspbuilder.DefaultSrc: {"self"},
		cspbuilder.ScriptSrc:  {"self", "www.google-analytics.com"},
		cspbuilder.ImgSrc:     {"*"},
	},
}

opt := secure.Options{
	ContentSecurityPolicy: cspBuilder.MustBuild(),
}

Integration examples

chi

// main.go
package main

import (
    "net/http"

    "github.com/pressly/chi"
    "github.com/unrolled/secure"
)

func main() {
    secureMiddleware := secure.New(secure.Options{
        FrameDeny: true,
    })

    r := chi.NewRouter()
    r.Use(secureMiddleware.Handler)

    r.Get("/", func(w http.ResponseWriter, r *http.Request) {
        w.Write([]byte("X-Frame-Options header is now `DENY`."))
    })

    http.ListenAndServe("127.0.0.1:3000", r)
}

Echo

// main.go
package main

import (
    "net/http"

    "github.com/labstack/echo"
    "github.com/unrolled/secure"
)

func main() {
    secureMiddleware := secure.New(secure.Options{
        FrameDeny: true,
    })

    e := echo.New()
    e.GET("/", func(c echo.Context) error {
        return c.String(http.StatusOK, "X-Frame-Options header is now `DENY`.")
    })

    e.Use(echo.WrapMiddleware(secureMiddleware.Handler))
    e.Logger.Fatal(e.Start("127.0.0.1:3000"))
}

Gin

// main.go
package main

import (
    "github.com/gin-gonic/gin"
    "github.com/unrolled/secure"
)

func main() {
    secureMiddleware := secure.New(secure.Options{
        FrameDeny: true,
    })
    secureFunc := func() gin.HandlerFunc {
        return func(c *gin.Context) {
            err := secureMiddleware.Process(c.Writer, c.Request)

            // If there was an error, do not continue.
            if err != nil {
                c.Abort()
                return
            }

            // Avoid header rewrite if response is a redirection.
            if status := c.Writer.Status(); status > 300 && status < 399 {
                c.Abort()
            }
        }
    }()

    router := gin.Default()
    router.Use(secureFunc)

    router.GET("/", func(c *gin.Context) {
        c.String(200, "X-Frame-Options header is now `DENY`.")
    })

    router.Run("127.0.0.1:3000")
}

Goji

// main.go
package main

import (
    "net/http"

    "github.com/unrolled/secure"
    "github.com/zenazn/goji"
    "github.com/zenazn/goji/web"
)

func main() {
    secureMiddleware := secure.New(secure.Options{
        FrameDeny: true,
    })

    goji.Get("/", func(c web.C, w http.ResponseWriter, req *http.Request) {
        w.Write([]byte("X-Frame-Options header is now `DENY`."))
    })
    goji.Use(secureMiddleware.Handler)
    goji.Serve() // Defaults to ":8000".
}

Iris

//main.go
package main

import (
    "github.com/kataras/iris/v12"
    "github.com/unrolled/secure"
)

func main() {
    app := iris.New()

    secureMiddleware := secure.New(secure.Options{
        FrameDeny: true,
    })

    app.Use(iris.FromStd(secureMiddleware.HandlerFuncWithNext))
    // Identical to:
    // app.Use(func(ctx iris.Context) {
    //     err := secureMiddleware.Process(ctx.ResponseWriter(), ctx.Request())
    //
    //     // If there was an error, do not continue.
    //     if err != nil {
    //         return
    //     }
    //
    //     ctx.Next()
    // })

    app.Get("/home", func(ctx iris.Context) {
        ctx.Writef("X-Frame-Options header is now `%s`.", "DENY")
    })

    app.Listen(":8080")
}

Mux

//main.go
package main

import (
    "log"
    "net/http"

    "github.com/gorilla/mux"
    "github.com/unrolled/secure"
)

func main() {
    secureMiddleware := secure.New(secure.Options{
        FrameDeny: true,
    })

    r := mux.NewRouter()
    r.Use(secureMiddleware.Handler)
    http.Handle("/", r)
    log.Fatal(http.ListenAndServe(fmt.Sprintf(":%d", 8080), nil))
}

Negroni

Note this implementation has a special helper function called HandlerFuncWithNext.

// main.go
package main

import (
    "net/http"

    "github.com/urfave/negroni"
    "github.com/unrolled/secure"
)

func main() {
    mux := http.NewServeMux()
    mux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
        w.Write([]byte("X-Frame-Options header is now `DENY`."))
    })

    secureMiddleware := secure.New(secure.Options{
        FrameDeny: true,
    })

    n := negroni.Classic()
    n.Use(negroni.HandlerFunc(secureMiddleware.HandlerFuncWithNext))
    n.UseHandler(mux)

    n.Run("127.0.0.1:3000")
}