67 lines
1.9 KiB
Go
67 lines
1.9 KiB
Go
package middleware
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import (
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"context"
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"net/http"
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"code.nonshy.com/nonshy/website/pkg/config"
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"code.nonshy.com/nonshy/website/pkg/log"
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"code.nonshy.com/nonshy/website/pkg/session"
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"code.nonshy.com/nonshy/website/pkg/templates"
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"github.com/google/uuid"
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)
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// CSRF middleware. Other places to look: pkg/session/session.go, pkg/templates/template_funcs.go
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func CSRF(handler http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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// Get or create the cookie CSRF value.
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token := MakeCSRFCookie(r, w)
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ctx := context.WithValue(r.Context(), session.CSRFKey, token)
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// If it's a JSON post, allow it thru.
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if r.Header.Get("Content-Type") == "application/json" {
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handler.ServeHTTP(w, r.WithContext(ctx))
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return
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}
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// If we are running a POST request, validate the CSRF form value.
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if r.Method != http.MethodGet {
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r.ParseMultipartForm(config.MultipartMaxMemory)
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check := r.FormValue(config.CSRFInputName)
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if check != token {
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log.Error("CSRF mismatch! %s <> %s", check, token)
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templates.MakeErrorPage(
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"CSRF Error",
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"An error occurred while processing your request. Please go back and try again.",
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http.StatusForbidden,
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)(w, r.WithContext(ctx))
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return
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}
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}
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handler.ServeHTTP(w, r.WithContext(ctx))
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})
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}
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// MakeCSRFCookie gets or creates the CSRF cookie and returns its value.
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func MakeCSRFCookie(r *http.Request, w http.ResponseWriter) string {
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// Has a token already?
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cookie, err := r.Cookie(config.CSRFCookieName)
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if err == nil {
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// log.Debug("MakeCSRFCookie: user has token %s", cookie.Value)
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return cookie.Value
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}
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// Generate a new CSRF token.
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token := uuid.New().String()
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cookie = &http.Cookie{
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Name: config.CSRFCookieName,
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Value: token,
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HttpOnly: true,
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}
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// log.Debug("MakeCSRFCookie: giving cookie value %s to user", token)
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http.SetCookie(w, cookie)
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return token
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}
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