added validuntil option

.gitignore

@@ -10,3 +10,5 @@ vendor/**/CONTRIBUTORS
 vendor/**/Makefile
 vendor/**/*_ZH.md
 vendor/**/*.sh
+
+cmd/imageproxy*/imageproxy*

cmd/imageproxy-sign/main_test.go

@@ -131,6 +131,9 @@ func TestParseURL(t *testing.T) {
 		// ensure signature values are stripped
 		{"http://localhost:8080/sc0ffee/http://example.com/", "http://example.com/#0x0"},
 		{"http://example.com/#sc0ffee", "http://example.com/#0x0"},
+
+		// validuntil
+		{"http://localhost:8080/vu20200304/http://example.com/", "http://example.com/#0x0,vu20200304"},
 	}
 
 	for _, tt := range tests {

data.go

@@ -41,6 +41,7 @@ const (
 	optCropWidth       = "cw"
 	optCropHeight      = "ch"
 	optSmartCrop       = "sc"
+	optValidUntil      = "vu"
 )
 
 // URLError reports a malformed URL error.
@@ -91,6 +92,9 @@ type Options struct {
 
 	// Automatically find good crop points based on image content.
 	SmartCrop bool
+
+	// Check if the URL is still valid in conjunction with a signature you can not change validity of a request.
+	ValidUntil int
 }
 
 func (o Options) String() string {
@@ -134,7 +138,12 @@ func (o Options) String() string {
 	if o.SmartCrop {
 		opts = append(opts, optSmartCrop)
 	}
+	if o.ValidUntil > 0 {
+		opts = append(opts, fmt.Sprintf("%s%d", optValidUntil, o.ValidUntil))
+	}
+
 	sort.Strings(opts)
+
 	return strings.Join(opts, ",")
 }
 
@@ -230,6 +239,11 @@ func (o Options) transform() bool {
 // See https://github.com/willnorris/imageproxy/blob/master/docs/url-signing.md
 // for examples of generating signatures.
 //
+// Validity
+//
+// The "vu{date}" option specifies a date until the request is valid. Please keep in mind
+// to not harm your browser caching TTL settings.
+//
 // Examples
 //
 // 	0x0         - no resizing
@@ -283,6 +297,9 @@ func ParseOptions(str string) Options {
 		case strings.HasPrefix(opt, optCropHeight):
 			value := strings.TrimPrefix(opt, optCropHeight)
 			options.CropHeight, _ = strconv.ParseFloat(value, 64)
+		case strings.HasPrefix(opt, optValidUntil):
+			value := strings.TrimPrefix(opt, optValidUntil)
+			options.ValidUntil, _ = strconv.Atoi(value)
 		case strings.Contains(opt, optSizeDelimiter):
 			size := strings.SplitN(opt, optSizeDelimiter, 2)
 			if w := size[0]; w != "" {

imageproxy.go

@@ -186,7 +186,6 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
 		copyHeader(actualReq.Header, r.Header, "referer")
 	}
 	resp, err := p.Client.Do(actualReq)
-
 	if err != nil {
 		msg := fmt.Sprintf("error fetching remote image: %v", err)
 		p.log(msg)
@@ -229,7 +228,7 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
 
 	copyHeader(w.Header(), resp.Header, "Content-Length")
 
-	//Enable CORS for 3rd party applications
+	// Enable CORS for 3rd party applications
 	w.Header().Set("Access-Control-Allow-Origin", "*")
 
 	w.WriteHeader(resp.StatusCode)
@@ -267,14 +266,22 @@ var (
 	errReferrer   = errors.New("request does not contain an allowed referrer")
 	errDeniedHost = errors.New("request contains a denied host")
 	errNotAllowed = errors.New("request does not contain an allowed host or valid signature")
+	errNotValid   = errors.New("request is no longer valid")
 
 	msgNotAllowed = "requested URL is not allowed"
 )
 
 // allowed determines whether the specified request contains an allowed
 // referrer, host, and signature.  It returns an error if the request is not
-// allowed.
+// allowed or not valid any longer.
 func (p *Proxy) allowed(r *Request) error {
+	if r.Options.ValidUntil > 0 {
+		y, m, d := time.Now().Date()
+		if r.Options.ValidUntil < y*10000+int(m)*100+d {
+			return errNotValid
+		}
+	}
+
 	if len(p.Referrers) > 0 && !referrerMatches(p.Referrers, r.Original) {
 		return errReferrer
 	}