Mitigate Apple Mail re-sync (both bodies and meta info)

pkg/pmapi/client.go

@@ -103,8 +103,9 @@ type ClientConfig struct {
 	// Zero means no limitation.
 	MinBytesPerSecond int64
 
-	NoConnectionHandler func()
-	ConnectionHandler   func()
+	ConnectionOnHandler       func()
+	ConnectionOffHandler      func()
+	UpgradeApplicationHandler func()
 }
 
 // client is a client of the protonmail API. It implements the Client interface.
@@ -265,6 +266,7 @@ func (c *client) doBuffered(req *http.Request, bodyBuffer []byte, retryUnauthori
 		if res == nil {
 			c.log.WithError(err).Error("Cannot get response")
 			err = ErrAPINotReachable
+			c.cm.noConnection()
 		}
 		return
 	}
@@ -405,6 +407,12 @@ func (c *client) doJSONBuffered(req *http.Request, reqBodyBuffer []byte, data in
 			}
 			return c.doJSONBuffered(req, reqBodyBuffer, data)
 		}
+		if errCode.Err() == ErrAPINotReachable {
+			c.cm.noConnection()
+		}
+		if errCode.Err() == ErrUpgradeApplication {
+			c.cm.config.UpgradeApplicationHandler()
+		}
 	}
 
 	if err := json.Unmarshal(resBody, data); err != nil {

pkg/pmapi/clientmanager.go

@@ -31,7 +31,7 @@ import (
 const maxLogoutRetries = 5
 
 // ClientManager is a manager of clients.
-type ClientManager struct {
+type ClientManager struct { //nolint[maligned]
 	// newClient is used to create new Clients. By default this creates pmapi clients but it can be overridden to
 	// create other types of clients (e.g. for integration tests).
 	newClient func(userID string) Client
@@ -61,6 +61,8 @@ type ClientManager struct {
 
 	idGen idGen
 
+	connectionOff bool
+
 	log *logrus.Entry
 }
 
@@ -108,6 +110,8 @@ func NewClientManager(config *ClientConfig) (cm *ClientManager) {
 		proxyProvider:    newProxyProvider(dohProviders, proxyQuery),
 		proxyUseDuration: proxyUseDuration,
 
+		connectionOff: false,
+
 		log: logrus.WithField("pkg", "pmapi-manager"),
 	}
 
@@ -121,6 +125,30 @@ func NewClientManager(config *ClientConfig) (cm *ClientManager) {
 	return cm
 }
 
+func (cm *ClientManager) noConnection() {
+	cm.log.Trace("No connection available")
+	if cm.connectionOff {
+		return
+	}
+
+	cm.log.Warn("Connection lost")
+	cm.config.ConnectionOffHandler()
+	cm.connectionOff = true
+
+	go func() {
+		for {
+			time.Sleep(30 * time.Second)
+
+			if err := cm.CheckConnection(); err == nil {
+				cm.log.Info("Connection re-established")
+				cm.config.ConnectionOnHandler()
+				cm.connectionOff = false
+				return
+			}
+		}
+	}()
+}
+
 // SetClientConstructor sets the method used to construct clients.
 // By default this is `pmapi.newClient` but can be overridden with this method.
 func (cm *ClientManager) SetClientConstructor(f func(userID string) Client) {

pkg/pmapi/dialer_proxy.go

@@ -37,17 +37,7 @@ func NewProxyTLSDialer(dialer TLSDialer, cm *ClientManager) *ProxyTLSDialer {
 }
 
 // DialTLS dials the given network/address. If it fails, it retries using a proxy.
-func (d *ProxyTLSDialer) DialTLS(network, address string) (net.Conn, error) {
-	conn, err := d.dialTLS(network, address)
-	if err != nil {
-		d.cm.config.NoConnectionHandler()
-	} else {
-		d.cm.config.ConnectionHandler()
-	}
-	return conn, err
-}
-
-func (d *ProxyTLSDialer) dialTLS(network, address string) (conn net.Conn, err error) {
+func (d *ProxyTLSDialer) DialTLS(network, address string) (conn net.Conn, err error) {
 	if conn, err = d.dialer.DialTLS(network, address); err == nil {
 		return
 	}