[feat] nim helper

3 files changed, 168 insertions, 0 deletions

diff --git a/helper/README.txt b/helper/README.txt
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--- /dev/null
+++ b/helper/README.txt
@@ -0,0 +1,2 @@
+This is a first prototype in Nim.
+It will be replaced by a helper in golang.
diff --git a/helper/bitmask_helper.nim b/helper/bitmask_helper.nim
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index 0000000..64333ee
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+++ b/helper/bitmask_helper.nim
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+# Bitmask Helper
+# A privileged helper that should run as a service in windows.
+
+import asyncdispatch, asyncnet
+import strutils
+import protocol
+import osproc
+
+type
+  Client = ref object
+    socket: AsyncSocket
+    netAddr: string
+    id: int
+    connected: bool
+
+  Server = ref object
+    socket: AsyncSocket
+    clients: seq[Client]
+    openvpnProc: seq[Process]
+
+proc newServer(): Server = Server(socket: newAsyncSocket(), clients: @[])
+proc `$`(client: Client): string =
+  $client.id & "(" & client.netAddr & ")"
+
+#
+# OpenVPN commands
+# 
+
+proc startOpenVPN(line: string, server: Server) =
+  let parsed = parseMessage(line)
+  echo(">>> start OpenVPN. \n  args:", parsed.args)
+  if server.openvpnProc.len == 0:
+    server.openvpnProc = @[]
+  if server.openvpnProc.len > 0 and running(server.openvpnProc[0]):
+    echo(">>> need to stop process first (len: ", server.openvpnProc.len, ")")
+    return
+
+  try:
+    # TODO sanitize args
+    let p = startProcess("c:/Program Files/OpenVPN/bin/openvpn.exe", args=split(parsed.args))
+    echo "LEN: ", len(server.openvpnProc)
+    if server.openvpnProc.len == 0:
+      server.openvpnProc.add(p)
+    else:
+      server.openvpnProc[0] = p
+  except OsError:
+    echo("error while launching process!")
+
+
+proc stopOpenVPN(line: string, server: Server) =
+  echo(">>> stop OpenVPN, \n  args:", parseMessage(line).args)
+  terminate(server.openvpnProc[0])
+
+
+proc doStatus(line: string, server: Server) =
+  if len(server.openvpnProc) == 1:
+    echo "running: ", running(server.openvpnProc[0])
+  else:
+    echo "no proc created"
+
+#
+# processing commands loop
+#
+
+proc processCommands(server: Server, client: Client) {.async.} =
+  while true:
+    let line = await client.socket.recvLine()
+    if line.len == 0:
+      echo(client, " disconnected!")
+      client.connected = false
+      client.socket.close()
+      return
+
+    echo("debug: ", client, " received: ", line)
+
+    try:
+      let parsed = parseMessage(line)
+      let cmd = parsed.cmd
+      case cmd
+      of "openvpn_start":
+        startOpenVPN(line, server)
+      of "openvpn_stop":
+        stopOpenVPN(line, server)
+      of "status":
+        doStatus(line, server)
+      of "ping":
+        ping(line, server)
+      else:
+        echo("Invalid command: ", cmd)
+   
+    except MessageParsingError:
+      echo("Invalid message:", line)
+
+
+proc loop(server: Server, port = 7171) {.async.} =
+  server.socket.bindAddr(port.Port, address = "127.0.0.1")
+  server.socket.listen()
+
+  while true:
+    let (netAddr, clientSocket) = await server.socket.acceptAddr()
+    echo("Accepted connection from ", netAddr)
+    let client = Client(
+      socket: clientSocket,
+      netAddr: netAddr,
+      id: server.clients.len,
+      connected: true
+    )
+    server.clients.add(client)
+    asyncCheck processCommands(server, client)
+
+var server = newServer()
+waitFor loop(server)
diff --git a/helper/protocol.nim b/helper/protocol.nim
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index 0000000..c7e097a
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+++ b/helper/protocol.nim
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+import json
+
+type
+  Message* = object
+    cmd*: string
+    args*: string
+
+  MessageParsingError* = object of Exception
+
+proc parseMessage*(data: string): Message {.raises: [MessageParsingError, KeyError].} =
+  var dataJson: JsonNode
+  try:
+    dataJson = parseJson(data)
+  except JsonParsingError:
+    raise newException(MessageParsingError, "Invalid JSON: " &
+                       getCurrentExceptionMsg())
+  except:
+    raise newException(MessageParsingError, "Unknown error: " &
+                       getCurrentExceptionMsg())
+
+  if not dataJson.hasKey("cmd"):
+    raise newException(MessageParsingError, "Cmd field missing")
+  result.cmd = dataJson["cmd"].getStr()
+  if result.cmd.len == 0:
+    raise newException(MessageParsingError, "Cmd field is empty")
+
+  if not dataJson.hasKey("args"):
+    raise newException(MessageParsingError, "Args field missing")
+  result.args = dataJson["args"].getStr()
+  if result.args.len == 0:
+    raise newException(MessageParsingError, "Args field is empty")
+
+proc createMessage*(cmd, args: string): string =
+  result = $(%{
+    "cmd": %cmd,
+    "args": %args
+  }) & "\c\l"
+
+when isMainModule:
+  block:
+    let data = """{"cmd": "status", "args": "verbose"}"""
+    let parsed = parseMessage(data)
+    doAssert parsed.cmd == "status"
+    doAssert parsed.args == "verbose"
+
+  # Test failure
+  block:
+    try:
+      let parsed = parseMessage("asdasd")
+    except MessageParsingError:
+      doAssert true
+    except:
+      doAssert false
+