Xss Middleware

XssMw is an middleware written in Golang for the Gin web framework. Although, it should be useable with any Go web framework which utilizes Golang's "net/http" native library in a similiar way to Gin.

The idea behind XssMw is to "auto remove XSS" from user submitted input.

It's applied on http GET, POST and PUT Requests only

The XSS filtering is performed by HTML sanitizer Bluemonday.

The default is to the strictest policy - StrictPolicy()

How To Use it?

Using the defaults, It will skip filtering for a field named 'password' but will run the filter on everything else. Uses the Bluemonday strictest policy - StrictPolicy()

package main

import "gopkg.in/gin-gonic/gin.v1"
import "github.com/dvwright/xss-mw"

func main() {
    r := gin.Default()

    // include as standard middleware
    var xssMdlwr xss.XssMw
    r.Use(xssMdlwr.RemoveXss())

    r.GET("/ping", func(c *gin.Context) {
        c.JSON(200, gin.H{
            "message": "pong",
        })
    })
    r.Run() // listen and serve on 0.0.0.0:8080
}

Using some config options, here It will skip filtering for a fields named 'password', "create_date" and "token" but will run the filter on everything else.

Uses Bluemonday UGCPolicy

package main

import "gopkg.in/gin-gonic/gin.v1"
import "github.com/dvwright/xss-mw"

func main() {
    r := gin.Default()

    xssMdlwr := &xss.XssMw{
            FieldsToSkip: []string{"password", "create_date", "token"},
            BmPolicy:     "UGCPolicy",
    }
    r.Use(xssMdlwr.RemoveXss())

    r.GET("/ping", func(c *gin.Context) {
        c.JSON(200, gin.H{
            "message": "pong",
        })
    })
    r.Run() // listen and serve on 0.0.0.0:8080
}

Data

Currently, it removes (deletes) all HTML and malicious detected input from user input on

the submitted request to the server.

It handles three Request types:

• JSON requests - Content-Type application/json

• Form Encoded - Content-Type application/x-www-form-urlencoded

• Multipart Form Data - Content-Type multipart/form-data

A future plan is have a feature to store all user submitted data intact and have the option to

filter it out on the http Response, so you can choose your preference. - in other words - data would be stored in the database as it was submitted and removed in Responses back to the user. pros: data integrity, cons: XSS exploits still present

NOTE: This is Beta level code with minimal actual real world usage

Contributing

You are welcome to contribute to this project.

Please update/add tests as appropriate.

Send pull request against the Develop branch.

Please use the same formatting as the Go authors. Run code through gofmt before submitting.

Thanks

Misc

Thanks to

https://github.com/goware/jsonp

https://github.com/appleboy/gin-jwt/tree/v2.1.1

Whose source I read throughly to aid in writing this

and of course

https://github.com/microcosm-cc/bluemonday

and the gin middleware

and

https://static.googleusercontent.com/intl/hu/about/appsecurity/learning/xss/

for inspiring me to to look for and not finding a framework, so attempting to write one.

A note on manually escaping input Writing your own code for escaping input and then properly and consistently applying it is extremely difficult. We do not recommend that you manually escape user-supplied data. Instead, we strongly recommend that you use a templating system or web development framework that provides context-aware auto-escaping.