Initial commit

nimchat.nimble

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+# Package
+
+version       = "0.1.0"
+author        = "zedeus"
+description   = "A chat application"
+license       = "GPL-3.0"
+srcDir        = "src"
+
+
+# Dependencies
+
+requires "nim >= 0.19.0"

src/client.nim

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+import asyncdispatch, asyncnet, os, threadpool, strutils, strformat
+import ./protocol
+
+type
+  Client = ref object
+    socket: AsyncSocket
+    server: string
+    port: int
+    username: string
+
+proc displayMessage(message: Message) =
+  echo &"{message.username}: {message.text}"
+
+proc connect(client: Client) {.async.} =
+  echo "Connecting to ", client.server
+  await connect(client.socket, client.server, Port(client.port))
+  echo "Connected!"
+
+proc login(client: Client) {.async.} =
+  echo "Logging in to ", client.server
+  let message = createMessage(client.username, "login", ConnectionMessage)
+  await client.socket.send(message)
+
+  let response = await client.socket.recvLine()
+  let parsed = parseMessage(response)
+
+  if parsed.mtype == ServiceMessage:
+    displayMessage(parsed)
+  elif parsed.mtype == ErrorMessage:
+    quit("ERROR: " & parsed.text)
+
+proc processMessages(client: Client) {.async.} =
+  while true:
+    let line = await client.socket.recvLine()
+    let parsed = parseMessage(line)
+    displayMessage(parsed)
+
+proc processInput(client: Client) {.async.} =
+  var messageFlowVar = spawn stdin.readLine()
+  while true:
+    if messageFlowVar.isReady():
+      let message = createMessage(client.username, ^messageFlowVar, TextMessage)
+      asyncCheck client.socket.send(message)
+      messageFlowVar = spawn stdin.readLine()
+    poll()
+
+proc newClient(): Client =
+  if paramCount() < 3:
+    quit("Please specify server address, port and username\nExample: ./client localhost 7687 user")
+
+  new(result)
+  result.server = paramStr(1)
+  result.port = parseInt(paramStr(2))
+  result.username = paramStr(3)
+  result.socket = newAsyncSocket()
+
+proc main() =
+  let client = newClient()
+  waitFor client.connect()
+  waitFor client.login()
+
+  asyncCheck client.processMessages()
+  waitFor client.processInput()
+
+main()

src/client.nims

@@ -0,0 +1 @@
+--threads:on

src/protocol.nim

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+import json, hashes, strutils
+
+type
+  MessageType* = enum
+    TextMessage, ServiceMessage, ConnectionMessage,
+    WarningMessage, ErrorMessage
+
+  Message* = object
+    username*: string
+    mtype*: MessageType
+    text*: string
+    hash*: int
+
+proc getHash*(username, text: string): int =
+  return hash(username & text)
+
+proc getHash*(message: Message): int =
+  return hash(message.username & message.text)
+
+proc verifyMessage*(message: Message): bool =
+  return getHash(message) == message.hash
+
+proc parseMessage*(data: string): Message =
+  let dataJson = parseJson(data)
+  result.username = dataJson["username"].getStr()
+  result.text = dataJson["text"].getStr()
+  result.mtype = parseEnum[MessageType](dataJson["mtype"].getStr())
+  result.hash = dataJson["hash"].getInt()
+
+proc createMessage*(username, text: string; mtype: MessageType): string =
+  result = $(%{
+    "username": %username,
+    "text": %text,
+    "mtype": %mtype,
+    "hash": %getHash(username, text)
+  }) & "\c\l"
+
+
+when isMainModule:
+  let hash = getHash("John" & "Hi!")
+  let data = """{"username": "John", "text": "Hi!", "hash": 6635146331310275049, "mtype": 0}"""
+
+  let parsed = parseMessage(data)
+  doAssert parsed.username == "John"
+  doAssert parsed.text == "Hi!"
+  doAssert parsed.hash == getHash("John" & "Hi!")
+  echo "All tests passed"

src/server.nim

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+import asyncdispatch, asyncnet, os, strformat, strutils
+import ./protocol
+
+type
+  Client = ref object
+    socket: AsyncSocket
+    netAddr: string
+    connected: bool
+    username: string
+    id: int
+
+  Server = ref object
+    socket: AsyncSocket
+    clients: seq[Client]
+
+proc newServer(): Server =
+  Server(socket: newAsyncSocket(), clients: @[])
+
+proc `$`(client: Client): string =
+  &"{client.id} ({client.netAddr})"
+
+proc sendMessage(client: Client; text: string; mtype: MessageType) {.async.} =
+  let message = createMessage("server", text, mtype)
+  await client.socket.send(message)
+
+proc sendError(client: Client; text: string) {.async.} =
+  await sendMessage(client, text, ErrorMessage)
+
+proc sendWarning(client: Client; text: string) {.async.} =
+  await sendMessage(client, text, WarningMessage)
+
+proc sendService(client: Client; text: string) {.async.} =
+  if not client.connected: return
+  await sendMessage(client, text, ServiceMessage)
+
+proc relayMessage(server: Server; message: string; skip=(-1)) {.async.} =
+  for c in server.clients:
+    if c.connected and (skip == -1 or c.id != skip):
+      await c.socket.send(message)
+
+proc broadcast(server: Server; text: string; skip=(-1); mtype=ServiceMessage) {.async.} =
+  let message = createMessage("server", text, mtype)
+  await relayMessage(server, message, skip)
+
+proc disconnect(client: Client) =
+  echo client, " disconnected!"
+  client.connected = false
+  client.username = ""
+  client.socket.close()
+
+proc handleLogin(server: Server; client: Client; message: Message) {.async.} =
+  if client.connected:
+    return
+
+  for c in server.clients:
+    if c.username == message.username:
+      await sendError(client, "Username already taken.")
+      return
+
+  client.username = message.username
+  client.connected = true
+
+  await sendService(client, "Login succesful.")
+  await server.broadcast(&"user \"{client.username}\" has joined")
+
+proc processMessage(server: Server; client: Client; message: string) {.async.} =
+  let parsed = parseMessage(message)
+  echo client, " sent: ", message
+
+  case parsed.mtype
+  of TextMessage:
+    if verifyMessage(parsed):
+      await relayMessage(server, message & "\c\l", skip=client.id)
+    else:
+      await sendWarning(client, "Message hash verification failed.")
+  of ConnectionMessage:
+    if parsed.text == "login":
+      await handleLogin(server, client, parsed)
+  else:
+    discard
+
+proc processClient(server: Server, client: Client) {.async.} =
+  while true:
+    let line = await client.socket.recvLine()
+    if line.len == 0:
+      if client.username != "":
+        await server.broadcast(&"user \"{client.username}\" disconnected", skip=client.id)
+
+      disconnect(client)
+      return
+
+    await processMessage(server, client, line)
+
+proc loop(server: Server) {.async.} =
+  while true:
+    let (netAddr, clientSocket) = await server.socket.acceptAddr()
+    let client = Client(
+      socket: clientSocket,
+      netAddr: netAddr,
+      connected: false,
+      id: server.clients.len
+    )
+    server.clients.add(client)
+    asyncCheck server.processClient(client)
+    echo "Accepted connection from ", netAddr, ", client id: ", client.id
+
+proc main() =
+  let server = newServer()
+  var port = 7687
+
+  if paramCount() == 1:
+    port = paramStr(1).parseInt
+
+  server.socket.bindAddr(Port(port))
+  server.socket.listen()
+  waitFor server.loop()
+
+main()