mirror of
https://github.com/rls-moe/nyx
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126 lines
3.5 KiB
Markdown
126 lines
3.5 KiB
Markdown
# nosurf
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[](https://travis-ci.org/justinas/nosurf)
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[](http://godoc.org/github.com/justinas/nosurf)
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`nosurf` is an HTTP package for Go
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that helps you prevent Cross-Site Request Forgery attacks.
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It acts like a middleware and therefore
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is compatible with basically any Go HTTP application.
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### Why?
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Even though CSRF is a prominent vulnerability,
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Go's web-related package infrastructure mostly consists of
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micro-frameworks that neither do implement CSRF checks,
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nor should they.
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`nosurf` solves this problem by providing a `CSRFHandler`
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that wraps your `http.Handler` and checks for CSRF attacks
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on every non-safe (non-GET/HEAD/OPTIONS/TRACE) method.
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`nosurf` requires Go 1.1 or later.
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### Features
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* Supports any `http.Handler` (frameworks, your own handlers, etc.)
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and acts like one itself.
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* Allows exempting specific endpoints from CSRF checks by
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an exact URL, a glob, or a regular expression.
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* Allows specifying your own failure handler.
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Want to present the hacker with an ASCII middle finger
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instead of the plain old `HTTP 400`? No problem.
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* Uses masked tokens to mitigate the BREACH attack.
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* Has no dependencies outside the Go standard library.
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### Example
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```go
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package main
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import (
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"fmt"
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"github.com/justinas/nosurf"
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"html/template"
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"net/http"
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)
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var templateString string = `
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<!doctype html>
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<html>
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<body>
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{{ if .name }}
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<p>Your name: {{ .name }}</p>
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{{ end }}
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<form action="/" method="POST">
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<input type="text" name="name">
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<!-- Try removing this or changing its value
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and see what happens -->
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<input type="hidden" name="csrf_token" value="{{ .token }}">
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<input type="submit" value="Send">
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</form>
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</body>
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</html>
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`
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var templ = template.Must(template.New("t1").Parse(templateString))
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func myFunc(w http.ResponseWriter, r *http.Request) {
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context := make(map[string]string)
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context["token"] = nosurf.Token(r)
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if r.Method == "POST" {
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context["name"] = r.FormValue("name")
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}
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templ.Execute(w, context)
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}
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func main() {
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myHandler := http.HandlerFunc(myFunc)
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fmt.Println("Listening on http://127.0.0.1:8000/")
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http.ListenAndServe(":8000", nosurf.New(myHandler))
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}
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```
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### Manual token verification
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In some cases the CSRF token may be send through a non standard way,
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e.g. a body or request is a JSON encoded message with one of the fields
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being a token.
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In such case the handler(path) should be excluded from an automatic
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verification by using one of the exemption methods:
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```go
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func (h *CSRFHandler) ExemptFunc(fn func(r *http.Request) bool)
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func (h *CSRFHandler) ExemptGlob(pattern string)
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func (h *CSRFHandler) ExemptGlobs(patterns ...string)
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func (h *CSRFHandler) ExemptPath(path string)
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func (h *CSRFHandler) ExemptPaths(paths ...string)
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func (h *CSRFHandler) ExemptRegexp(re interface{})
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func (h *CSRFHandler) ExemptRegexps(res ...interface{})
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```
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Later on, the token **must** be verified by manually getting the token from the cookie
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and providing the token sent in body through: `VerifyToken(tkn, tkn2 string) bool`.
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Example:
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```go
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func HandleJson(w http.ResponseWriter, r *http.Request) {
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d := struct{
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X,Y int
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Tkn string
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}{}
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json.Unmarshal(ioutil.ReadAll(r.Body), &d)
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if !nosurf.VerifyToken(Token(r), d.Tkn) {
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http.Errorf(w, "CSRF token incorrect", http.StatusBadRequest)
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return
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}
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// do smth cool
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}
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```
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### Contributing
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0. Find an issue that bugs you / open a new one.
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1. Discuss.
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2. Branch off, commit, test.
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3. Make a pull request / attach the commits to the issue.
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