package replacepathregex import ( "context" "fmt" "net/http" "net/url" "regexp" "strings" "github.com/traefik/traefik/v3/pkg/config/dynamic" "github.com/traefik/traefik/v3/pkg/middlewares" "github.com/traefik/traefik/v3/pkg/middlewares/replacepath" "github.com/traefik/traefik/v3/pkg/tracing" "go.opentelemetry.io/otel/trace" ) const typeName = "ReplacePathRegex" // ReplacePathRegex is a middleware used to replace the path of a URL request with a regular expression. type replacePathRegex struct { next http.Handler regexp *regexp.Regexp replacement string name string } // New creates a new replace path regex middleware. func New(ctx context.Context, next http.Handler, config dynamic.ReplacePathRegex, name string) (http.Handler, error) { middlewares.GetLogger(ctx, name, typeName).Debug().Msg("Creating middleware") exp, err := regexp.Compile(strings.TrimSpace(config.Regex)) if err != nil { return nil, fmt.Errorf("error compiling regular expression %s: %w", config.Regex, err) } return &replacePathRegex{ regexp: exp, replacement: strings.TrimSpace(config.Replacement), next: next, name: name, }, nil } func (rp *replacePathRegex) GetTracingInformation() (string, string, trace.SpanKind) { return rp.name, typeName, trace.SpanKindInternal } func (rp *replacePathRegex) ServeHTTP(rw http.ResponseWriter, req *http.Request) { currentPath := req.URL.RawPath if currentPath == "" { currentPath = req.URL.EscapedPath() } if rp.regexp != nil && len(rp.replacement) > 0 && rp.regexp.MatchString(currentPath) { req.Header.Add(replacepath.ReplacedPathHeader, currentPath) req.URL.RawPath = rp.regexp.ReplaceAllString(currentPath, rp.replacement) // as replacement can introduce escaped characters // Path must remain an unescaped version of RawPath // Doesn't handle multiple times encoded replacement (`/` => `%2F` => `%252F` => ...) var err error req.URL.Path, err = url.PathUnescape(req.URL.RawPath) if err != nil { middlewares.GetLogger(context.Background(), rp.name, typeName).Error().Err(err).Send() tracing.SetStatusErrorf(req.Context(), err.Error()) http.Error(rw, err.Error(), http.StatusInternalServerError) return } req.RequestURI = req.URL.RequestURI() } rp.next.ServeHTTP(rw, req) }