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