| // Copyright 2015 The Vanadium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Package acls provides a library to assist servers implementing |
| // GetPermissions/SetPermissions functions. |
| package acls |
| |
| import ( |
| "bytes" |
| "crypto/md5" |
| "encoding/hex" |
| |
| "v.io/v23/security/access" |
| ) |
| |
| // ComputeEtag produces the tag value returned by access.GetPermissions() (per |
| // v.io/v23/security/access/service.vdl) that GetPermissions()/SetPermissions() |
| // use to determine if the AccessLists have been asynchronously modified. |
| func ComputeEtag(acl access.Permissions) (string, error) { |
| b := new(bytes.Buffer) |
| if err := acl.WriteTo(b); err != nil { |
| return "", err |
| } |
| |
| md5hash := md5.Sum(b.Bytes()) |
| etag := hex.EncodeToString(md5hash[:]) |
| return etag, nil |
| } |
