106 lines
2.6 KiB
Go
106 lines
2.6 KiB
Go
package middleware
|
|
|
|
import (
|
|
"net/http"
|
|
"strings"
|
|
)
|
|
|
|
// CSRFProtect returns middleware that validates the Origin header on
|
|
// state-changing methods (POST, PUT, PATCH, DELETE).
|
|
//
|
|
// An origin is trusted if:
|
|
// 1. It's in the explicit additionalOrigins list, OR
|
|
// 2. Its hostname matches the configured host, OR
|
|
// 3. Its hostname matches the request's own Host header (same-origin check)
|
|
func CSRFProtect(host, port string, additionalOrigins []string) func(http.Handler) http.Handler {
|
|
originSet := make(map[string]struct{})
|
|
for _, o := range additionalOrigins {
|
|
o = strings.TrimSpace(o)
|
|
if o != "" {
|
|
originSet[o] = struct{}{}
|
|
}
|
|
}
|
|
|
|
hostname := host
|
|
if idx := strings.LastIndex(hostname, ":"); idx > 0 {
|
|
hostname = hostname[:idx]
|
|
}
|
|
|
|
return func(next http.Handler) http.Handler {
|
|
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
|
|
switch r.Method {
|
|
case "POST", "PUT", "PATCH", "DELETE":
|
|
origin := r.Header.Get("Origin")
|
|
if origin == "" {
|
|
referer := r.Header.Get("Referer")
|
|
if referer != "" {
|
|
for o := range originSet {
|
|
if strings.HasPrefix(referer, o) {
|
|
origin = o
|
|
break
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if origin != "" {
|
|
// Extract request host for same-origin check
|
|
reqHost := r.Host
|
|
if idx := strings.LastIndex(reqHost, ":"); idx > 0 {
|
|
reqHost = reqHost[:idx]
|
|
}
|
|
|
|
if !isOriginTrusted(origin, hostname, port, reqHost, originSet) {
|
|
http.Error(w, `{"error":"forbidden origin"}`, http.StatusForbidden)
|
|
return
|
|
}
|
|
}
|
|
}
|
|
next.ServeHTTP(w, r)
|
|
})
|
|
}
|
|
}
|
|
|
|
func isOriginTrusted(origin, host, port, reqHost string, originSet map[string]struct{}) bool {
|
|
if _, ok := originSet[origin]; ok {
|
|
return true
|
|
}
|
|
|
|
withoutScheme := origin
|
|
if idx := strings.Index(withoutScheme, "://"); idx >= 0 {
|
|
withoutScheme = withoutScheme[idx+3:]
|
|
}
|
|
if idx := strings.Index(withoutScheme, "/"); idx >= 0 {
|
|
withoutScheme = withoutScheme[:idx]
|
|
}
|
|
|
|
originHost := withoutScheme
|
|
originPort := ""
|
|
if idx := strings.LastIndex(originHost, ":"); idx >= 0 {
|
|
originPort = originHost[idx+1:]
|
|
originHost = originHost[:idx]
|
|
}
|
|
|
|
originHost = strings.TrimPrefix(originHost, "[")
|
|
originHost = strings.TrimSuffix(originHost, "]")
|
|
|
|
// Match configured host
|
|
if host != "" && originHost == host {
|
|
return true
|
|
}
|
|
|
|
// Match request's own Host header (same-origin)
|
|
if reqHost != "" && originHost == reqHost {
|
|
return true
|
|
}
|
|
|
|
// Localhost variants
|
|
if originHost == "localhost" || originHost == "127.0.0.1" || originHost == "::1" {
|
|
if port == "" || originPort == "" || originPort == port {
|
|
return true
|
|
}
|
|
}
|
|
|
|
return false
|
|
}
|