github.com/greenpau/go-identity@v1.1.6/random.go (about)

     1  // Copyright 2020 Paul Greenberg greenpau@outlook.com
     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  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package identity
    16  
    17  import (
    18  	"math/rand"
    19  	"time"
    20  )
    21  
    22  const charset = "abcdefghijklmnopqrstuvwxyz" +
    23  	"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    24  
    25  var seed *rand.Rand = rand.New(
    26  	rand.NewSource(time.Now().UnixNano()),
    27  )
    28  
    29  func gen(length int, charset string) string {
    30  	b := make([]byte, length)
    31  	for i := range b {
    32  		b[i] = charset[seed.Intn(len(charset))]
    33  	}
    34  	return string(b)
    35  }
    36  
    37  // GetRandomString returns X character long random string.
    38  func GetRandomString(i int) string {
    39  	if i < 1 {
    40  		i = 40
    41  	}
    42  	return gen(i, charset)
    43  }
    44  
    45  // GetRandomStringFromRange generates random string of a random length. The
    46  // random lenght is bounded by a and b.
    47  func GetRandomStringFromRange(a, b int) string {
    48  	var i int
    49  	if a > b {
    50  		i = rand.Intn(a-b) + b
    51  	} else {
    52  		i = rand.Intn(b-a) + a
    53  	}
    54  	return gen(i, charset)
    55  }