mirror of
https://github.com/tailscale/tailscale.git
synced 2024-11-25 11:05:45 +00:00
71029cea2d
This updates all source files to use a new standard header for copyright and license declaration. Notably, copyright no longer includes a date, and we now use the standard SPDX-License-Identifier header. This commit was done almost entirely mechanically with perl, and then some minimal manual fixes. Updates #6865 Signed-off-by: Will Norris <will@tailscale.com>
67 lines
1.9 KiB
Go
67 lines
1.9 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
|
|
// SPDX-License-Identifier: BSD-3-Clause
|
|
|
|
package main
|
|
|
|
import (
|
|
"encoding/json"
|
|
"os"
|
|
)
|
|
|
|
// Cache contains cached information about the last time this tool was run.
|
|
//
|
|
// This is serialized to a JSON file that should NOT be checked into git.
|
|
// It should be managed with either CI cache tools or stored locally somehow. The
|
|
// exact mechanism is irrelevant as long as it is consistent.
|
|
//
|
|
// This allows gitops-pusher to detect external ACL changes. I'm not sure what to
|
|
// call this problem, so I've been calling it the "three version problem" in my
|
|
// notes. The basic problem is that at any given time we only have two versions
|
|
// of the ACL file at any given point. In order to check if there has been
|
|
// tampering of the ACL files in the admin panel, we need to have a _third_ version
|
|
// to compare against.
|
|
//
|
|
// In this case I am not storing the old ACL entirely (though that could be a
|
|
// reasonable thing to add in the future), but only its sha256sum. This allows
|
|
// us to detect if the shasum in control matches the shasum we expect, and if that
|
|
// expectation fails, then we can react accordingly.
|
|
type Cache struct {
|
|
PrevETag string // Stores the previous ETag of the ACL to allow
|
|
}
|
|
|
|
// Save persists the cache to a given file.
|
|
func (c *Cache) Save(fname string) error {
|
|
os.Remove(fname)
|
|
fout, err := os.Create(fname)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer fout.Close()
|
|
|
|
return json.NewEncoder(fout).Encode(c)
|
|
}
|
|
|
|
// LoadCache loads the cache from a given file.
|
|
func LoadCache(fname string) (*Cache, error) {
|
|
var result Cache
|
|
|
|
fin, err := os.Open(fname)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer fin.Close()
|
|
|
|
err = json.NewDecoder(fin).Decode(&result)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return &result, nil
|
|
}
|
|
|
|
// Shuck removes the first and last character of a string, analogous to
|
|
// shucking off the husk of an ear of corn.
|
|
func Shuck(s string) string {
|
|
return s[1 : len(s)-1]
|
|
}
|