Stickiness cookie name

server/cookie/cookie.go

@@ -0,0 +1,57 @@
+package cookie
+
+import (
+	"crypto/sha1"
+	"fmt"
+	"strings"
+
+	"github.com/containous/traefik/log"
+)
+
+const cookieNameLength = 6
+
+// GetName of a cookie
+func GetName(cookieName string, backendName string) string {
+	if len(cookieName) != 0 {
+		return sanitizeName(cookieName)
+	}
+
+	return GenerateName(backendName)
+}
+
+// GenerateName Generate a hashed name
+func GenerateName(backendName string) string {
+	data := []byte("_TRAEFIK_BACKEND_" + backendName)
+
+	hash := sha1.New()
+	_, err := hash.Write(data)
+	if err != nil {
+		// Impossible case
+		log.Errorf("Fail to create cookie name: %v", err)
+	}
+
+	return fmt.Sprintf("_%x", hash.Sum(nil))[:cookieNameLength]
+}
+
+// sanitizeName According to [RFC 2616](https://www.ietf.org/rfc/rfc2616.txt) section 2.2
+func sanitizeName(backend string) string {
+	sanitizer := func(r rune) rune {
+		switch r {
+		case '!', '#', '$', '%', '&', '\'', '*', '+', '-', '.', '^', '`', '|', '~':
+			return r
+		}
+
+		switch {
+		case 'a' <= r && r <= 'z':
+			fallthrough
+		case 'A' <= r && r <= 'Z':
+			fallthrough
+		case '0' <= r && r <= '9':
+			return r
+		default:
+			return '_'
+		}
+	}
+
+	return strings.Map(sanitizer, backend)
+}