How to sanitize input data in golang?

Question

I am trying to sanitize input shortly before marshaling the submitted data into a specified struct.

Here is the model that I am using.

type Post struct {
    Id               int       `json:"Id"`
    CreatedAt        time.Time `json:"CreatedAt"`
    UpdatedAt        time.Time `json:"UpdatedAt"`
    CreatorId        int       `json:"CreatorId"`
    Creator          *User
    Editors          []int  `json:"Editors"`
    Status           Status `json:"Status"`
    Title            string `json:"Title"`
    ShortDescription string `json:"ShortDescription"`
    Description      string `json:"Description"`
    Content          string `json:"Content"`
    Url              string `json:"Url"`
    Media            *Media
    Categories       []Category `json:"Categories"`
    Tags             []Tag      `json:"Tags"`
    MediaId          int        `json:"MediaId"`
    Keywords         string     `json:"Keywords"`
    Data             []string   `json:"Data"`
}

Here is an example of a possible submitted JSON data

{"Id":1,"CreatedAt":"2016-10-11T21:29:46.134+02:00","UpdatedAt":"0001-01-01T00:00:00Z","CreatorId":1,"Editors":null,"Status":1,"Title":"This is the title of the first post, to be changed.<script>alert()</script>","ShortDescription":"this is the short description of this post","Description":"","Content":"Contrary to popular belief Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC making it over 2000 years old. Richard McClintock","Url":"lorem-ipsum-first"}

How would I most effectively sanitize the above JSON form data during the ReadJSON request and before data insertion during this process, thus removing any malicious code as seen with <script>alert()</script>.? If there is any additional information that could be of use please ask and I will be glad to add it. Thanks

Answer 1

For HTML Sanitizing you could try github.com/microcosm-cc/bluemonday.

For validating JSON input data as per rules you set.

This article is a good read on the topic.

An example from the article.

type User struct {
     Name string    `json:"name"    validate:"nonzero"`
     Age uint       `json:"age"     validate:"min=1"`
     Address string `json:"address" validate:"nonzero"`
}

The package used for validation is gopkg.in/validator.v2

Usage :

user := &models.User{}
if err = c.ReadJSON(user); err != nil {
    // Handle Error
}

p := bluemonday.UGCPolicy()
user.Name, user.Address = p.Sanitize(user.Name),p.Sanitize(user.Address)

if err = validator.Validate(user); err != nil {
   // Handle Error
}

err = db.Create(&user)
if err != nil {
    // Handle Error
}