func()

in registry/client/auth/session.go [400:480]

• 60 lines of code
• 18 McCabe index (conditional complexity)

func (th *tokenHandler) fetchTokenWithBasicAuth(realm *url.URL, service string, scopes []string) (token string, expiration time.Time, err error) {
	req, err := http.NewRequest(http.MethodGet, realm.String(), nil)
	if err != nil {
		return "", time.Time{}, err
	}

	reqParams := req.URL.Query()

	if service != "" {
		reqParams.Add("service", service)
	}

	for _, scope := range scopes {
		reqParams.Add("scope", scope)
	}

	if th.offlineAccess {
		reqParams.Add("offline_token", "true")
		clientID := th.clientID
		if clientID == "" {
			clientID = defaultClientID
		}
		reqParams.Add("client_id", clientID)
	}

	if th.creds != nil {
		username, password := th.creds.Basic(realm)
		if username != "" && password != "" {
			reqParams.Add("account", username)
			req.SetBasicAuth(username, password)
		}
	}

	req.URL.RawQuery = reqParams.Encode()

	resp, err := th.client().Do(req)
	if err != nil {
		return "", time.Time{}, err
	}
	defer resp.Body.Close()

	if !client.SuccessStatus(resp.StatusCode) {
		err := client.HandleErrorResponse(resp)
		return "", time.Time{}, err
	}

	decoder := json.NewDecoder(resp.Body)

	var tr getTokenResponse
	if err = decoder.Decode(&tr); err != nil {
		return "", time.Time{}, fmt.Errorf("decoding token response: %w", err)
	}

	if tr.RefreshToken != "" && th.creds != nil {
		th.creds.SetRefreshToken(realm, service, tr.RefreshToken)
	}

	// `access_token` is equivalent to `token` and if both are specified
	// the choice is undefined.  Canonicalize `access_token` by sticking
	// things in `token`.
	if tr.AccessToken != "" {
		tr.Token = tr.AccessToken
	}

	if tr.Token == "" {
		return "", time.Time{}, ErrNoToken
	}

	if tr.ExpiresIn < minimumTokenLifetimeSeconds {
		// The default/minimum lifetime.
		tr.ExpiresIn = minimumTokenLifetimeSeconds
		logDebugf(th.logger, "Increasing token expiration to: %d seconds", tr.ExpiresIn)
	}

	if tr.IssuedAt.IsZero() {
		// issued_at is optional in the token response.
		tr.IssuedAt = th.clock.Now().UTC()
	}

	return tr.Token, tr.IssuedAt.Add(time.Duration(tr.ExpiresIn) * time.Second), nil
}