package redirect import ( "bytes" "html/template" "io" "net/http" "net/url" "regexp" "strings" "github.com/containous/traefik/v2/pkg/tracing" "github.com/opentracing/opentracing-go/ext" "github.com/vulcand/oxy/utils" ) type redirect struct { next http.Handler regex *regexp.Regexp replacement string permanent bool errHandler utils.ErrorHandler name string } // New creates a Redirect middleware. func newRedirect(next http.Handler, regex, replacement string, permanent bool, name string) (http.Handler, error) { re, err := regexp.Compile(regex) if err != nil { return nil, err } return &redirect{ regex: re, replacement: replacement, permanent: permanent, errHandler: utils.DefaultHandler, next: next, name: name, }, nil } func (r *redirect) GetTracingInformation() (string, ext.SpanKindEnum) { return r.name, tracing.SpanKindNoneEnum } func (r *redirect) ServeHTTP(rw http.ResponseWriter, req *http.Request) { oldURL := rawURL(req) // If the Regexp doesn't match, skip to the next handler if !r.regex.MatchString(oldURL) { r.next.ServeHTTP(rw, req) return } // apply a rewrite regexp to the URL newURL := r.regex.ReplaceAllString(oldURL, r.replacement) // replace any variables that may be in there rewrittenURL := &bytes.Buffer{} if err := applyString(newURL, rewrittenURL, req); err != nil { r.errHandler.ServeHTTP(rw, req, err) return } // parse the rewritten URL and replace request URL with it parsedURL, err := url.Parse(rewrittenURL.String()) if err != nil { r.errHandler.ServeHTTP(rw, req, err) return } if newURL != oldURL { handler := &moveHandler{location: parsedURL, permanent: r.permanent} handler.ServeHTTP(rw, req) return } req.URL = parsedURL // make sure the request URI corresponds the rewritten URL req.RequestURI = req.URL.RequestURI() r.next.ServeHTTP(rw, req) } type moveHandler struct { location *url.URL permanent bool } func (m *moveHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request) { rw.Header().Set("Location", m.location.String()) status := http.StatusFound if req.Method != http.MethodGet { status = http.StatusTemporaryRedirect } if m.permanent { status = http.StatusMovedPermanently if req.Method != http.MethodGet { status = http.StatusPermanentRedirect } } rw.WriteHeader(status) _, err := rw.Write([]byte(http.StatusText(status))) if err != nil { http.Error(rw, err.Error(), http.StatusInternalServerError) } } func rawURL(req *http.Request) string { scheme := "http" host := req.Host port := "" uri := req.RequestURI schemeRegex := `^(https?):\/\/(\[[\w:.]+\]|[\w\._-]+)?(:\d+)?(.*)$` re, _ := regexp.Compile(schemeRegex) if re.Match([]byte(req.RequestURI)) { match := re.FindStringSubmatch(req.RequestURI) scheme = match[1] if len(match[2]) > 0 { host = match[2] } if len(match[3]) > 0 { port = match[3] } uri = match[4] } if req.TLS != nil { scheme = "https" } return strings.Join([]string{scheme, "://", host, port, uri}, "") } func applyString(in string, out io.Writer, req *http.Request) error { t, err := template.New("t").Parse(in) if err != nil { return err } data := struct{ Request *http.Request }{Request: req} return t.Execute(out, data) }