Add support for VS985 and others

The udev rules and Wireshark dissector still have idProduct hardcoded
for the time being, but lglaf.py detection logic is converted to use
heuristics instead.

Thanks to @invisiblek for testing and providing lsusb output.

lglaf.lua

@@ -95,5 +95,6 @@ end
 
 function lglaf.init()
     local usb_product = DissectorTable.get("usb.product");
-    usb_product:add(0x1004633e, lglaf)
+    usb_product:add(0x1004633e, lglaf) -- LG G3 D855
+    usb_product:add(0x1004627f, lglaf) -- LG G3 VS985
 end

lglaf.py

@@ -13,7 +13,7 @@ import argparse, logging, re, struct, sys
 try: import readline
 except ImportError: pass
 # Try USB interface
-try: import usb.core
+try: import usb.core, usb.util
 except ImportError: pass
 # Windows registry for serial port detection
 try: import winreg
@@ -192,13 +192,31 @@ class FileCommunication(Communication):
 class USBCommunication(Communication):
     EP_IN = 0x85
     EP_OUT = 3
+    VENDOR_ID_LG = 0x1004
     # Read timeout. Set to 0 to disable timeouts
     READ_TIMEOUT_MS = 0
     def __init__(self):
         super(USBCommunication, self).__init__()
-        self.usbdev = usb.core.find(idVendor=0x1004, idProduct=0x633e)
+        # Match device using heuristics on the interface/endpoint descriptors,
+        # this avoids hardcoding idProduct.
+        self.usbdev = usb.core.find(idVendor=self.VENDOR_ID_LG,
+                custom_match = self._match_device)
         if self.usbdev is None:
             raise RuntimeError("USB device not found")
+    def _match_device(self, device):
+        return any(
+            usb.util.find_descriptor(cfg, bInterfaceClass=255,
+                    bInterfaceSubClass=255, bInterfaceProtocol=255,
+                    custom_match=self._match_interface)
+            for cfg in device
+        )
+    def _match_interface(self, intf):
+        return intf.bNumEndpoints == 2 and all(
+            ep.bEndpointAddress in (self.EP_IN, self.EP_OUT) and
+            usb.util.endpoint_type(ep.bmAttributes) ==
+                usb.util.ENDPOINT_TYPE_BULK
+            for ep in intf
+        )
     def _read(self, n):
         # device seems to use 16 KiB buffers.
         array = self.usbdev.read(self.EP_IN, 2**14, timeout=self.READ_TIMEOUT_MS)

rules.d/42-usb-lglaf.rules

@@ -1,3 +1,5 @@
 # /etc/udev/rules.d/42-usb-lglaf.rules
-# LG G3 in download mode
+# LG G3 (D855) in download mode
 SUBSYSTEM=="usb", ATTRS{idVendor}=="1004", ATTRS{idProduct}=="633e", TAG+="uaccess"
+# LG G3 (VS985) in download mode
+SUBSYSTEM=="usb", ATTRS{idVendor}=="1004", ATTRS{idProduct}=="627f", TAG+="uaccess"