fix: CSRF and WS origin check trust request Host header (same-origin)

This commit is contained in:
2026-06-29 14:38:18 -04:00
parent 7f56571004
commit a8a09cf7b4
2 changed files with 139 additions and 123 deletions
+34 -15
View File
@@ -26,8 +26,11 @@ var upgrader = websocket.Upgrader{
}
// SetAllowedOrigins replaces the default upgrader with one that validates
// the Origin header against a trusted set. Call once at startup.
// Exact matches are checked first, then hostname-based matching is used.
// the Origin header. Accepts if:
// 1. Exact match in origins list, OR
// 2. Hostname matches a trusted hostname, OR
// 3. Hostname matches the request's own Host header (same-origin), OR
// 4. Localhost variant
func SetAllowedOrigins(origins []string) {
originSet := make(map[string]struct{}, len(origins))
hostSet := make(map[string]struct{}, len(origins))
@@ -53,34 +56,50 @@ func SetAllowedOrigins(origins []string) {
CheckOrigin: func(r *http.Request) bool {
origin := r.Header.Get("Origin")
if origin == "" {
return true // non-browser clients
return true
}
if _, ok := originSet[origin]; ok {
return true
}
oh := origin
if idx := strings.Index(oh, "://"); idx >= 0 {
oh = oh[idx+3:]
}
if idx := strings.Index(oh, "/"); idx >= 0 {
oh = oh[:idx]
}
if idx := strings.LastIndex(oh, ":"); idx >= 0 {
oh = oh[:idx]
}
oh = strings.TrimPrefix(oh, "[")
oh = strings.TrimSuffix(oh, "]")
oh := extractHostname(origin)
// Match trusted hostnames
if _, ok := hostSet[oh]; ok {
return true
}
// Match request's own Host header (same-origin)
reqHost := extractHostname(r.Host)
if reqHost != "" && oh == reqHost {
return true
}
// Localhost variants
if oh == "localhost" || oh == "127.0.0.1" || oh == "::1" {
return true
}
return false
},
}
}
func extractHostname(s string) string {
h := s
if idx := strings.Index(h, "://"); idx >= 0 {
h = h[idx+3:]
}
if idx := strings.Index(h, "/"); idx >= 0 {
h = h[:idx]
}
if idx := strings.LastIndex(h, ":"); idx >= 0 {
h = h[:idx]
}
h = strings.TrimPrefix(h, "[")
h = strings.TrimSuffix(h, "]")
return h
}
// Client is a middleman between the websocket connection and the hub.
type Client struct {
Hub *Hub
+105 -108
View File
@@ -1,108 +1,105 @@
package middleware
import (
"net/http"
"strings"
)
// CSRFProtect returns middleware that validates the Origin header on
// state-changing methods (POST, PUT, PATCH, DELETE). Requests from origins
// not in the trustedOrigins list are rejected with 403. Non-browser clients
// (curl, bots) that send no Origin or Referer header are allowed through,
// since they are not subject to CSRF.
//
// If host is non-empty, any Origin whose hostname matches host is allowed.
// additionalOrigins is a list of extra fully-qualified origins to trust
// (e.g. from environment variable DUMPSTER_CSRF_ORIGINS, comma-separated).
func CSRFProtect(host, port string, additionalOrigins []string) func(http.Handler) http.Handler {
// Build a set of exact-match origins for quick lookup
originSet := make(map[string]struct{})
for _, o := range additionalOrigins {
o = strings.TrimSpace(o)
if o != "" {
originSet[o] = struct{}{}
}
}
// Extract hostname from host (strip port if present)
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 == "" {
// Fallback: extract origin from Referer
referer := r.Header.Get("Referer")
if referer != "" {
for o := range originSet {
if strings.HasPrefix(referer, o) {
origin = o
break
}
}
}
}
if origin != "" {
if !isOriginTrusted(origin, hostname, port, originSet) {
http.Error(w, `{"error":"forbidden origin"}`, http.StatusForbidden)
return
}
}
// If both Origin and Referer are empty, allow through
// (non-browser client like curl, bots, mobile apps)
}
next.ServeHTTP(w, r)
})
}
}
// isOriginTrusted checks if the given Origin header value is trusted.
// An origin is trusted if:
// 1. It's in the explicit originSet, OR
// 2. Its hostname matches the configured host (any scheme/port)
func isOriginTrusted(origin, host, port string, originSet map[string]struct{}) bool {
if _, ok := originSet[origin]; ok {
return true
}
// Parse the origin to extract hostname and port
// Origin format: scheme://host[:port]
withoutScheme := origin
if idx := strings.Index(withoutScheme, "://"); idx >= 0 {
withoutScheme = withoutScheme[idx+3:]
}
// Remove path if any
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]
}
// Strip brackets from IPv6
originHost = strings.TrimPrefix(originHost, "[")
originHost = strings.TrimSuffix(originHost, "]")
if host != "" && originHost == host {
return true
}
// Also trust localhost variants
if originHost == "localhost" || originHost == "127.0.0.1" || originHost == "::1" {
if port == "" || originPort == "" || originPort == port {
return true
}
}
return false
}
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
}