github.com/dhax/go-base@v0.0.0-20231004214136-8be7e5c1972b/auth/pwdless/logintoken.go (about)

     1  package pwdless
     2  
     3  import (
     4  	"crypto/rand"
     5  	"errors"
     6  	"sync"
     7  	"time"
     8  
     9  	"github.com/spf13/viper"
    10  )
    11  
    12  var (
    13  	errTokenNotFound = errors.New("login token not found")
    14  )
    15  
    16  // LoginToken is an in-memory saved token referencing an account ID and an expiry date.
    17  type LoginToken struct {
    18  	Token     string
    19  	AccountID int
    20  	Expiry    time.Time
    21  }
    22  
    23  // LoginTokenAuth implements passwordless login authentication flow using temporary in-memory stored tokens.
    24  type LoginTokenAuth struct {
    25  	token            map[string]LoginToken
    26  	mux              sync.RWMutex
    27  	loginURL         string
    28  	loginTokenLength int
    29  	loginTokenExpiry time.Duration
    30  }
    31  
    32  // NewLoginTokenAuth configures and returns a LoginToken authentication instance.
    33  func NewLoginTokenAuth() (*LoginTokenAuth, error) {
    34  	a := &LoginTokenAuth{
    35  		token:            make(map[string]LoginToken),
    36  		loginURL:         viper.GetString("auth_login_url"),
    37  		loginTokenLength: viper.GetInt("auth_login_token_length"),
    38  		loginTokenExpiry: viper.GetDuration("auth_login_token_expiry"),
    39  	}
    40  	return a, nil
    41  }
    42  
    43  // CreateToken creates an in-memory login token referencing account ID. It returns a token containing a random tokenstring and expiry date.
    44  func (a *LoginTokenAuth) CreateToken(id int) LoginToken {
    45  	lt := LoginToken{
    46  		Token:     randStringBytes(a.loginTokenLength),
    47  		AccountID: id,
    48  		Expiry:    time.Now().Add(a.loginTokenExpiry),
    49  	}
    50  	a.add(lt)
    51  	a.purgeExpired()
    52  	return lt
    53  }
    54  
    55  // GetAccountID looks up the token by tokenstring and returns the account ID or error if token not found or expired.
    56  func (a *LoginTokenAuth) GetAccountID(token string) (int, error) {
    57  	lt, exists := a.get(token)
    58  	if !exists || time.Now().After(lt.Expiry) {
    59  		return 0, errTokenNotFound
    60  	}
    61  	a.delete(lt.Token)
    62  	return lt.AccountID, nil
    63  }
    64  
    65  func (a *LoginTokenAuth) get(token string) (LoginToken, bool) {
    66  	a.mux.RLock()
    67  	lt, ok := a.token[token]
    68  	a.mux.RUnlock()
    69  	return lt, ok
    70  }
    71  
    72  func (a *LoginTokenAuth) add(lt LoginToken) {
    73  	a.mux.Lock()
    74  	a.token[lt.Token] = lt
    75  	a.mux.Unlock()
    76  }
    77  
    78  func (a *LoginTokenAuth) delete(token string) {
    79  	a.mux.Lock()
    80  	delete(a.token, token)
    81  	a.mux.Unlock()
    82  }
    83  
    84  func (a *LoginTokenAuth) purgeExpired() {
    85  	for t, v := range a.token {
    86  		if time.Now().After(v.Expiry) {
    87  			a.delete(t)
    88  		}
    89  	}
    90  }
    91  
    92  const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    93  
    94  func randStringBytes(n int) string {
    95  	buf := make([]byte, n)
    96  	if _, err := rand.Read(buf); err != nil {
    97  		panic(err)
    98  	}
    99  
   100  	for k, v := range buf {
   101  		buf[k] = letterBytes[v%byte(len(letterBytes))]
   102  	}
   103  	return string(buf)
   104  }