105 lines
2.9 KiB
Go
105 lines
2.9 KiB
Go
// This file is part of MinIO Console Server
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// Copyright (c) 2020 MinIO, Inc.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package restapi
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import (
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"crypto/rand"
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"io"
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"os"
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"strings"
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)
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// Do not use:
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// https://stackoverflow.com/questions/22892120/how-to-generate-a-random-string-of-a-fixed-length-in-go
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// It relies on math/rand and therefore not on a cryptographically secure RNG => It must not be used
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// for access/secret keys.
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// The alphabet of random character string. Each character must be unique.
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//
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// The RandomCharString implementation requires that: 256 / len(letters) is a natural numbers.
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// For example: 256 / 64 = 4. However, 5 > 256/62 > 4 and therefore we must not use a alphabet
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// of 62 characters.
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// The reason is that if 256 / len(letters) is not a natural number then certain characters become
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// more likely then others.
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const letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ012345"
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func RandomCharStringWithAlphabet(n int, alphabet string) string {
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random := make([]byte, n)
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if _, err := io.ReadFull(rand.Reader, random); err != nil {
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panic(err) // Can only happen if we would run out of entropy.
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}
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var s strings.Builder
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for _, v := range random {
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j := v % byte(len(alphabet))
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s.WriteByte(alphabet[j])
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}
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return s.String()
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}
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func RandomCharString(n int) string {
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return RandomCharStringWithAlphabet(n, letters)
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}
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// DifferenceArrays returns the elements in `a` that aren't in `b`.
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func DifferenceArrays(a, b []string) []string {
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mb := make(map[string]struct{}, len(b))
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for _, x := range b {
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mb[x] = struct{}{}
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}
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var diff []string
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for _, x := range a {
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if _, found := mb[x]; !found {
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diff = append(diff, x)
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}
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}
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return diff
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}
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// IsElementInArray returns true if the string belongs to the slice
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func IsElementInArray(a []string, b string) bool {
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for _, e := range a {
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if e == b {
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return true
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}
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}
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return false
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}
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// UniqueKeys returns an array without duplicated keys
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func UniqueKeys(a []string) []string {
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keys := make(map[string]bool)
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list := []string{}
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for _, entry := range a {
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if _, value := keys[entry]; !value {
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keys[entry] = true
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list = append(list, entry)
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}
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}
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return list
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}
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// FileExists verifies if a file exist on the desired location and its not a folder
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func FileExists(filename string) bool {
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info, err := os.Stat(filename)
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if os.IsNotExist(err) {
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return false
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}
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return !info.IsDir()
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}
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