From 673f633d34b1919a1ce4ba57376502a1cf3f0259 Mon Sep 17 00:00:00 2001
From: s-ol <s+removethis@s-ol.nu>
Date: Sun, 18 Feb 2024 19:41:59 +0100
Subject: initial commit

---
 ch340.lua | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100755 ch340.lua

(limited to 'ch340.lua')

diff --git a/ch340.lua b/ch340.lua
new file mode 100755
index 0000000..37adef7
--- /dev/null
+++ b/ch340.lua
@@ -0,0 +1,118 @@
+local ch340_ctl = Proto("ch340.ctl", "CH340 Serial Control")
+local ch340_bulk = Proto("ch340.bulk", "CH340 Serial Data")
+
+local ep_dir_f = Field.new("usb.endpoint_address.direction")
+
+local REQ_TBL = {
+	[0x5F] = "CH341_REQ_READ_VERSION",
+	[0x9A] = "CH341_REQ_WRITE_REG",
+	[0x95] = "CH341_REQ_READ_REG",
+	[0xA1] = "CH341_REQ_SERIAL_INIT",
+	[0xA4] = "CH341_REQ_MODEM_CTRL",
+}
+
+local REG_TBL = {
+  [0x07] = "STATUS2",
+  [0x06] = "STATUS",
+  [0x13] = "DIVISOR",
+  [0x12] = "PRESCALER",
+  [0x18] = "LCR",
+  [0x25] = "LCR2",
+}
+
+local req_F = ProtoField.uint8("ch340.ctl.req", "Request", base.HEX, REQ_TBL)
+local reg1_F = ProtoField.uint8("ch340.ctl.reg1", "Register 1", base.HEX, REG_TBL)
+local reg2_F = ProtoField.uint8("ch340.ctl.reg2", "Register 2", base.HEX, REG_TBL)
+local val1_F = ProtoField.uint8("ch340.ctl.val1", "Value 1", base.HEX)
+local val2_F = ProtoField.uint8("ch340.ctl.val2", "Value 2", base.HEX)
+local modem_F = ProtoField.uint8("ch340.ctl.modem", "Modem", base.HEX)
+
+ch340_ctl.fields = {
+	req_F,
+	reg1_F,
+	val1_F,
+	reg2_F,
+	val2_F,
+	modem_F,
+}
+
+local data_in_F = ProtoField.bytes("ch340.bulk.data_in", "Data In")
+local data_out_F = ProtoField.bytes("ch340.bulk.data_out", "Data Out")
+
+ch340_bulk.fields = {
+	data_in_F,
+	data_out_F,
+}
+
+local serial_tbl = DissectorTable.heuristic_new("ch340.serial_data", ch340_bulk)
+
+function ch340_ctl.dissector(buffer, pinfo, tree)
+  if buffer:captured_len() < 1 then return end
+
+  local sub = tree:add(ch340_ctl, buffer())
+
+  local req = buffer(0, 1)
+  sub:add(req_F, req)
+
+  req = REQ_TBL[req:uint()]
+	pinfo.cols.info:set("CH340 " .. req:sub(11))
+	if req == "CH341_REQ_WRITE_REG" or
+  	 req == "CH341_REQ_READ_REG" then
+
+  	local reg2 = buffer(1, 1)
+  	local reg1 = buffer(2, 1)
+		sub:add(reg1_F, reg1)
+		sub:add(reg2_F, reg2)
+
+		reg1 = reg1:uint()
+		reg2 = reg2:uint()
+
+		pinfo.cols.info:append(string.format(" %s/%s", (REG_TBL[reg1] or reg1), (REG_TBL[reg2] or reg2)))
+
+		if req == "CH341_REQ_WRITE_REG" then
+    	local val2 = buffer(3, 1)
+    	local val1 = buffer(4, 1)
+  		sub:add(val1_F, val1)
+  		sub:add(val2_F, val2)
+  	end
+	elseif name == "CH341_REQ_MODEM_CTRL" then
+		sub:add(modem_F, buffer(1))
+	end
+end
+
+function ch340_bulk.dissector(buffer, pinfo, tree)
+  if buffer:captured_len() < 1 then return end
+
+	local sub = tree:add(ch340_bulk, buffer())
+	pinfo.cols.info:set("CH340 Serial")
+
+	local ep_dir = ep_dir_f()() -- 0: h2d, 1: d2h
+	if ep_dir == 0 then
+  	pinfo.cols.info:append(" out")
+  	pinfo.p2p_dir = P2P_DIR_SENT
+  	sub:add(data_out_F, buffer())
+  else
+  	pinfo.cols.info:append(" in")
+  	pinfo.p2p_dir = P2P_DIR_RECV
+  	sub:add(data_in_F, buffer())
+	end
+
+	DissectorTable.try_heuristics("ch340.serial_data", buffer, pinfo, tree)
+end
+
+function usb_protocol_key(class, subclass, protocol)
+  return bit.bor(
+    bit.lshift(1, 31),
+    bit.lshift(bit.band(class, 0xff), 16),
+    bit.lshift(bit.band(subclass, 0xff), 8),
+    bit.band(protocol, 0xff)
+  )
+end
+
+local ctl_table = DissectorTable.get("usb.control")
+ctl_table:add(usb_protocol_key(0xff, 0x01, 0x02), ch340_ctl)
+ctl_table:add(0xffff, ch340_ctl)
+
+local bulk_table = DissectorTable.get("usb.bulk")
+bulk_table:add(usb_protocol_key(0xff, 0x01, 0x02), ch340_bulk)
+bulk_table:add(0xffff, ch340_bulk)
-- 
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