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acl.go
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acl.go
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// Copyright 2018-2021 CERN
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// In applying this license, CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
package acl
import (
"errors"
"fmt"
"strings"
)
// The ACLs represent a delimiter separated list of ACL entries.
type ACLs struct {
Entries []*Entry
delimiter string
}
var (
errInvalidACL = errors.New("invalid acl")
)
const (
// LongTextForm contains one ACL entry per line.
LongTextForm = "\n"
// ShortTextForm is a sequence of ACL entries separated by commas, and is used for input.
ShortTextForm = ","
// TypeUser indicates the qualifier identifies a user
TypeUser = "u"
// TypeLightweight indicates the qualifier identifies a lightweight user
TypeLightweight = "lw"
// TypeGroup indicates the qualifier identifies a group
TypeGroup = "egroup"
)
// Parse parses an acl string with the given delimiter (LongTextForm or ShortTextForm)
func Parse(acls string, delimiter string) (*ACLs, error) {
tokens := strings.Split(acls, delimiter)
entries := []*Entry{}
for _, t := range tokens {
// ignore empty lines and comments
if t == "" || isComment(t) {
continue
}
var err error
var entry *Entry
if strings.HasPrefix(t, TypeLightweight) {
entry, err = ParseLWEntry(t)
} else {
entry, err = ParseEntry(t)
}
if err != nil {
return nil, err
}
entries = append(entries, entry)
}
return &ACLs{Entries: entries, delimiter: delimiter}, nil
}
func isComment(line string) bool {
return strings.HasPrefix(line, "#")
}
// Serialize always serializes to short text form
func (m *ACLs) Serialize() string {
sysACL := []string{}
for _, e := range m.Entries {
sysACL = append(sysACL, e.CitrineSerialize())
}
return strings.Join(sysACL, ShortTextForm)
}
// DeleteEntry removes an entry uniquely identified by acl type and qualifier
func (m *ACLs) DeleteEntry(aclType string, qualifier string) {
for i, e := range m.Entries {
if e.Qualifier == qualifier && e.Type == aclType {
m.Entries = append(m.Entries[:i], m.Entries[i+1:]...)
return
}
}
}
// SetEntry replaces the permissions of an entry with the given set
func (m *ACLs) SetEntry(aclType string, qualifier string, permissions string) error {
if aclType == "" || permissions == "" {
return errInvalidACL
}
m.DeleteEntry(aclType, qualifier)
entry := &Entry{
Type: aclType,
Qualifier: qualifier,
Permissions: permissions,
}
m.Entries = append(m.Entries, entry)
return nil
}
// The Entry of an ACL is represented as three colon separated fields:
type Entry struct {
// an ACL entry tag type: user, group, mask or other. comments start with #
Type string
// an ACL entry qualifier
Qualifier string
// and the discretionary access permissions
Permissions string
}
// ParseEntry parses a single ACL
func ParseEntry(singleSysACL string) (*Entry, error) {
tokens := strings.Split(singleSysACL, ":")
switch len(tokens) {
case 2:
// The ACL entries might be stored as type:qualifier=permissions
// Handle that case separately
parts := strings.SplitN(tokens[1], "=", 2)
if len(parts) == 2 {
return &Entry{
Type: tokens[0],
Qualifier: parts[0],
Permissions: parts[1],
}, nil
}
case 3:
return &Entry{
Type: tokens[0],
Qualifier: tokens[1],
Permissions: tokens[2],
}, nil
}
return nil, errInvalidACL
}
// ParseLWEntry parses a single lightweight ACL
func ParseLWEntry(singleSysACL string) (*Entry, error) {
if !strings.HasPrefix(singleSysACL, TypeLightweight+":") {
return nil, errInvalidACL
}
singleSysACL = strings.TrimPrefix(singleSysACL, TypeLightweight+":")
tokens := strings.Split(singleSysACL, "=")
if len(tokens) != 2 {
return nil, errInvalidACL
}
return &Entry{
Type: TypeLightweight,
Qualifier: tokens[0],
Permissions: tokens[1],
}, nil
}
// CitrineSerialize serializes an ACL entry for citrine EOS ACLs
func (a *Entry) CitrineSerialize() string {
return fmt.Sprintf("%s:%s=%s", a.Type, a.Qualifier, a.Permissions)
}