refactor auth pkg into libraries

auth/pwdless/logintoken.go

@@ -0,0 +1,104 @@
+package pwdless
+
+import (
+	"crypto/rand"
+	"errors"
+	"sync"
+	"time"
+
+	"github.com/spf13/viper"
+)
+
+var (
+	errTokenNotFound = errors.New("login token not found")
+)
+
+// LoginToken is an in-memory saved token referencing an account ID and an expiry date.
+type LoginToken struct {
+	Token     string
+	AccountID int
+	Expiry    time.Time
+}
+
+// LoginTokenAuth implements passwordless login authentication flow using temporary in-memory stored tokens.
+type LoginTokenAuth struct {
+	token            map[string]LoginToken
+	mux              sync.RWMutex
+	loginURL         string
+	loginTokenLength int
+	loginTokenExpiry time.Duration
+}
+
+// NewLoginTokenAuth configures and returns a LoginToken authentication instance.
+func NewLoginTokenAuth() (*LoginTokenAuth, error) {
+	a := &LoginTokenAuth{
+		token:            make(map[string]LoginToken),
+		loginURL:         viper.GetString("auth_login_url"),
+		loginTokenLength: viper.GetInt("auth_login_token_length"),
+		loginTokenExpiry: viper.GetDuration("auth_login_token_expiry"),
+	}
+	return a, nil
+}
+
+// CreateToken creates an in-memory login token referencing account ID. It returns a token containing a random tokenstring and expiry date.
+func (a *LoginTokenAuth) CreateToken(id int) LoginToken {
+	lt := LoginToken{
+		Token:     randStringBytes(a.loginTokenLength),
+		AccountID: id,
+		Expiry:    time.Now().Add(a.loginTokenExpiry),
+	}
+	a.add(lt)
+	a.purgeExpired()
+	return lt
+}
+
+// GetAccountID looks up the token by tokenstring and returns the account ID or error if token not found or expired.
+func (a *LoginTokenAuth) GetAccountID(token string) (int, error) {
+	lt, exists := a.get(token)
+	if !exists || time.Now().After(lt.Expiry) {
+		return 0, errTokenNotFound
+	}
+	a.delete(lt.Token)
+	return lt.AccountID, nil
+}
+
+func (a *LoginTokenAuth) get(token string) (LoginToken, bool) {
+	a.mux.RLock()
+	lt, ok := a.token[token]
+	a.mux.RUnlock()
+	return lt, ok
+}
+
+func (a *LoginTokenAuth) add(lt LoginToken) {
+	a.mux.Lock()
+	a.token[lt.Token] = lt
+	a.mux.Unlock()
+}
+
+func (a *LoginTokenAuth) delete(token string) {
+	a.mux.Lock()
+	delete(a.token, token)
+	a.mux.Unlock()
+}
+
+func (a *LoginTokenAuth) purgeExpired() {
+	for t, v := range a.token {
+		if time.Now().After(v.Expiry) {
+			a.delete(t)
+		}
+	}
+}
+
+const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+
+func randStringBytes(n int) string {
+	buf := make([]byte, n)
+	if _, err := rand.Read(buf); err != nil {
+		panic(err)
+	}
+
+	for k, v := range buf {
+		buf[k] = letterBytes[v%byte(len(letterBytes))]
+	}
+	return string(buf)
+}