Cycle the socket after linking a new device.

Signal/src/ViewControllers/AppSettings/OWSLinkDeviceViewController.m

@@ -169,6 +169,10 @@ NS_ASSUME_NONNULL_BEGIN
         dispatch_async(dispatch_get_main_queue(), ^{
             [self.linkedDevicesTableViewController expectMoreDevices];
             [self.navigationController popToViewController:self.linkedDevicesTableViewController animated:YES];
+
+            // The service implementation of the socket connection caches the linked device state,
+            // so all sync message sends will fail on the socket until it is cycled.
+            [TSSocketManager.sharedManager cycleSocket];
         });
     }
         failure:^(NSError *error) {

SignalServiceKit/src/Network/WebSockets/TSSocketManager.h

@@ -41,6 +41,9 @@ typedef void (^TSSocketMessageFailure)(NSInteger statusCode, NSData *_Nullable r
 // This method can be called from any thread.
 + (void)requestSocketOpen;
 
+// This can be used to force the socket to close and re-open, if it is open.
+- (void)cycleSocket;
+
 #pragma mark - Message Sending
 
 + (BOOL)canMakeRequests;

SignalServiceKit/src/Network/WebSockets/TSSocketManager.m

@@ -800,6 +800,15 @@ NSString *const kNSNotification_SocketManagerStateDidChange = @"kNSNotification_
     }
 }
 
+- (void)cycleSocket
+{
+    OWSAssertIsOnMainThread();
+
+    [self closeWebSocket];
+
+    [self applyDesiredSocketState];
+}
+
 - (void)handleSocketFailure
 {
     OWSAssertIsOnMainThread();