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package oauth
import (
"fmt"
"sync"
"time"
"github.com/go-errors/errors"
)
// TokenResponse defines the OAuth response from the server that includes the tokens.
type TokenResponse struct {
// Access is the access token returned by the server
Access string `json:"access_token"`
// Refresh token is the refresh token returned by the server
Refresh string `json:"refresh_token"`
// Type indicates which type of tokens we have
Type string `json:"token_type"`
// Expires is the expires time returned by the server
Expires int64 `json:"expires_in"`
}
// token is a structure that contains our access and refresh tokens and a timestamp when they expire.
type token struct {
// Access is the access token returned by the server
access string
// Refresh token is the refresh token returned by the server
refresh string
// ExpiredTimestamp is the Expires field but converted to a Go timestamp
expiredTimestamp time.Time
// Refresher is the function that refreshes the token
Refresher func(string) (*TokenResponse, time.Time, error)
}
// tokenLock is a wrapper around token that protects it with a lock
type tokenLock struct {
// Protects t
mu sync.Mutex
// The token fields protected by the lock
t *token
}
// Access gets the OAuth access token used for contacting the server API
// It returns the access token as a string, possibly obtained fresh using the refresher
// If the token cannot be obtained, an error is returned and the token is an empty string.
func (l *tokenLock) Access() (string, error) {
l.mu.Lock()
defer l.mu.Unlock()
// The tokens are not expired yet
// So they should be valid, re-login not neede
if !l.expired() {
return l.t.access, nil
}
// Check if refresh is even possible by doing a simple check if the refresh token is empty
// This is not needed but reduces API calls to the server
if l.t.refresh == "" {
return "", errors.Wrap(&TokensInvalidError{Cause: "no refresh token is present"}, 0)
}
// Otherwise refresh and then later return the access token if we are successful
tr, s, err := l.t.Refresher(l.t.refresh)
if err != nil {
// We have failed to ensure the tokens due to refresh not working
return "", errors.Wrap(
&TokensInvalidError{Cause: fmt.Sprintf("tokens failed refresh with error: %v", err)}, 0)
}
if tr == nil {
return "", errors.New("No token response after refreshing")
}
l.updateInternal(*tr, s)
return l.t.access, nil
}
// Clear completely clears the token structure
// This is useful for forcing re-authorization
func (l *tokenLock) Clear() {
l.mu.Lock()
l.t = &token{}
l.mu.Unlock()
}
// updateInternal updates the structure using the response without locking
func (l *tokenLock) updateInternal(r TokenResponse, s time.Time) {
l.t.access = r.Access
l.t.refresh = r.Refresh
l.t.expiredTimestamp = s.Add(time.Second * time.Duration(r.Expires))
}
// Update updates the structure usign the response and locks
func (l *tokenLock) Update(r TokenResponse, s time.Time) {
l.mu.Lock()
l.updateInternal(r, s)
l.mu.Unlock()
}
// SetExpired overrides the timestamp to the current time
// This marks the tokens as expired
func (l *tokenLock) SetExpired() {
l.mu.Lock()
l.t.expiredTimestamp = time.Now()
l.mu.Unlock()
}
// expired checks if the access token is expired.
// This is only called internally and thus does not lock
func (l *tokenLock) expired() bool {
now := time.Now()
return !now.Before(l.t.expiredTimestamp)
}
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