github.com/kovansky/hugo@v0.92.3-0.20220224232819-63076e4ff19f/config/security/whitelist.go (about)

     1  // Copyright 2021 The Hugo Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package security
    15  
    16  import (
    17  	"encoding/json"
    18  	"fmt"
    19  	"regexp"
    20  	"strings"
    21  )
    22  
    23  const (
    24  	acceptNoneKeyword = "none"
    25  )
    26  
    27  // Whitelist holds a whitelist.
    28  type Whitelist struct {
    29  	acceptNone bool
    30  	patterns   []*regexp.Regexp
    31  
    32  	// Store this for debugging/error reporting
    33  	patternsStrings []string
    34  }
    35  
    36  func (w Whitelist) MarshalJSON() ([]byte, error) {
    37  	if w.acceptNone {
    38  		return json.Marshal(acceptNoneKeyword)
    39  	}
    40  
    41  	return json.Marshal(w.patternsStrings)
    42  }
    43  
    44  // NewWhitelist creates a new Whitelist from zero or more patterns.
    45  // An empty patterns list or a pattern with the value 'none' will create
    46  // a whitelist that will Accept noone.
    47  func NewWhitelist(patterns ...string) Whitelist {
    48  	if len(patterns) == 0 {
    49  		return Whitelist{acceptNone: true}
    50  	}
    51  
    52  	var acceptSome bool
    53  	var patternsStrings []string
    54  
    55  	for _, p := range patterns {
    56  		if p == acceptNoneKeyword {
    57  			acceptSome = false
    58  			break
    59  		}
    60  
    61  		if ps := strings.TrimSpace(p); ps != "" {
    62  			acceptSome = true
    63  			patternsStrings = append(patternsStrings, ps)
    64  		}
    65  	}
    66  
    67  	if !acceptSome {
    68  		return Whitelist{
    69  			acceptNone: true,
    70  		}
    71  	}
    72  
    73  	var patternsr []*regexp.Regexp
    74  
    75  	for i := 0; i < len(patterns); i++ {
    76  		p := strings.TrimSpace(patterns[i])
    77  		if p == "" {
    78  			continue
    79  		}
    80  		patternsr = append(patternsr, regexp.MustCompile(p))
    81  	}
    82  
    83  	return Whitelist{patterns: patternsr, patternsStrings: patternsStrings}
    84  }
    85  
    86  // Accepted reports whether name is whitelisted.
    87  func (w Whitelist) Accept(name string) bool {
    88  	if w.acceptNone {
    89  		return false
    90  	}
    91  
    92  	for _, p := range w.patterns {
    93  		if p.MatchString(name) {
    94  			return true
    95  		}
    96  	}
    97  	return false
    98  }
    99  
   100  func (w Whitelist) String() string {
   101  	return fmt.Sprint(w.patternsStrings)
   102  }