TCP client server chat program

This code has been declared by its author to be Public Domain code.

TCP client server chat program by semar (Posted 25 years ago)
An example on how to use TCP commands with a simple but complete chat program that can work in a network and in internet.
;=========== CLIENT CODE ======================= ;TCP Client program ;by Sergio Marcello ;semar63@hotmail.com ;http://www.sergiomarcello.com ;the port which to connect to - the server and the client should communicate on the same port value port = 40000 ;was 1024, but sometime is used by nowadays pc. ;sets the graphics to a windowed scaled mode Graphics 640,480,16,3 AppTitle "CHAT CLIENT" ;the channel stream that will be assigned from the server once connected. Global client_stream ;const for keyboard space and esc keys Const k_space = 57 Const k_esc = 1 ;ask for a nickname client_id$ = Input$("Enter your nickname: ") ;if no nickame then end If client_id$ = "" Then End ;attempts to open a socket (stream) on the remote server, with the default port = port ;========= ATTENTION ======================== ;here the IP address should be the one of the server !!! ;right now this value is just to allow testing on a local machine. Prompt the user to ;type in the right ip address, if you want a remote connection !!! strmClient=OpenTCPStream("127.0.0.1",port) ;checks if the stream connection was successfully estabilished If strmClient<>0 Then Print "Client successfully connected" Else Print "Server failed to connect - quitting." WaitKey End End If ;first, write the client nickname to the server msg$ = "UID" + client_id$ WriteLine strmClient,msg$ ;until ESC is pressed While Not KeyDown(k_esc) ;if space bar pressed, then input a message If KeyDown(k_space) ;waits until space bar is released While KeyDown(k_space) Wend ;ask for a message to send message$ = Input$("Your message: ") ;writes the message on the stream channel - that is, sends a message to the server msg$ = "MSG" + message$ WriteLine strmClient, msg$ EndIf ;listen for incoming messages ;if a message is queued then retrieves it If ReadAvail (strmClient) Then ;gets the message message$ = ReadLine$ (strmClient) ;checks if is a message from the server If Mid$(message$,1,3) = "SRV" Then ;select the second part of the header what$ = Mid$(message$,4,3) Select what$ Case "_ID" ;the server has sent this client unique ID stream client_stream = Mid$(message$,7) ;Print "client_stream = " + client_stream Case "BYE" ;server disconnected ! Color 255,0,0 Print " - The server has disconnected - press esc key to quit - " Color 255,255,255 Default ;unknown message Print " - Unknown message from the server - " End Select Else ;it's a simple broadcast message ;prints in red color a disconnection message If Instr(Upper(message$),Upper("disconnected")) Then Color 255,0,0 EndIf ;shows the message Print "<" + message$ + ">" Color 255,255,255 EndIf EndIf ;small delay Delay 30 Wend ;logging out from server msg$ = "ESC" + client_stream WriteLine strmClient,msg$ Delay 30 End ;========== SERVER CODE ================== ;TCP SERVER program ;by Sergio Marcello ;semar63@hotmail.com ;www.sergiomarcello.com Graphics 640,480,16,3 ;windowed scaled mode ;sets the title of the application AppTitle "CHAT SERVER" Global received_stream Const k_space = 57 Const k_esc = 1 ;creates a type of client with two items: client name, and client ID stream Type client Field uid$ Field stream End Type ;declare a global type variable for the client Global c.client ;sets the port where to listen from, and where the client can connect to. port = 40000 ;was 1024, but sometime is used by nowadays pc. ;Create a server and listen for client connections svrGame=CreateTCPServer(port) ;checks if the server was successfully created; if not, ends the program If svrGame<>0 Then Print "Server started successfully - listening on port " + port Else Print "Server failed to start on port " + port End End If ;===================================================================== ;Main loop until ESC is pressed While Not KeyDown(k_esc) message$ = "" ;checks if there is a NEW client connection strStream=AcceptTCPStream(svrGame) If strStream Then ;a new client has joined the chat; his ID stream is strStream ;memorize the current connection stream received_stream = strStream ;reads info from the client just connected (see tcp_client.bb) If ReadAvail(strStream) Then message$ = ReadLine$(strStream) EndIf Else ;there are NOT new connections; so checks if there are incoming data from clients For c.client = Each client If ReadAvail(c\stream) Then ;Print "incoming message from client: " + c\UID received_stream = c\stream the_user$ = c\uid$ message$ = ReadLine$(c\stream) Exit EndIf Next EndIf If message$ <> "" Then ;a message has arrived, or a new client has joined the chat ;processes the data from the client: ;checks the header of the message header$ = Mid$(message$,1,3) ;tests the header Select header$ Case "UID" ;it's a NEW client connection ;extracts the user ID the_user$ = Mid$(message$,4) ;creates a new client type structure and memorize userid and stream number c.client = New client c\uid = the_user$ c\stream = strstream ;notifyes to the client his stream number WriteLine c\stream, "SRV_ID" + c\stream ;broadcasts the new client connection msg_new$ = "<" + the_user$ + "> connected !" notify_message(msg_new$) Case "MSG" ;it's a message from a client ;broadcasts the user message msg_new$ = "<" + the_user$ + "> " + Mid$(message,4) notify_message(msg_new$) Case "ESC";a client has disconnected from the chat ;extracts the client ID stream that was sent from the client in the message client_stream = Mid(message$,4) ;locate the client name from the list of the client For c.client = Each client If c\stream = client_stream Then ;retrieve the client id the_user$ = c\uid ;delete the client Delete c ;exit for Exit EndIf Next ;broadcasts the message msg_new$ = "<" + the_user$ + "> Disconnected" notify_message(msg_new$) End Select ;small pause Delay 20 EndIf ;if space bar pressed, then input a message If KeyDown(k_space) ;waits until space bar is released While KeyDown(k_space) Wend ;ask for a message to send message$ = Input$("Your message: ") ;prepare the message to be sent msg_new$ = "<server> " + message$ ;broadcasts the message notify_message(msg_new$) EndIf Wend ;quitting ;sends a logoff message to all the client notify_message("SRVBYE") Delay 20 End ;=============================== Function notify_message(msg_new$) ;=============================== ;notifyes the message on the server itself If Instr(Upper(msg_new$),Upper("disconnected")) Then Color 255,0,0 EndIf ;shows only client messages If received_stream <> 0 Then Print msg_new$ EndIf Color 255,255,255 ;notifyes the message to all the logged clients, but the sender c.client = First client For c.client = Each client If c\stream <> received_stream Then WriteLine c\stream,msg_new$ EndIf Next received_stream = 0 End Function

TCP client server chat program by semar

(Posted 25 years ago)

An example on how to use TCP commands with a simple but complete chat program that can work in a network and in internet.

;=========== CLIENT CODE =======================
;TCP Client program
;by Sergio Marcello
;semar63@hotmail.com
;http://www.sergiomarcello.com

;the port which to connect to - the server and the client should communicate on the same port value
port = 40000 ;was 1024, but sometime is used by nowadays pc.

;sets the graphics to a windowed scaled mode
Graphics 640,480,16,3
AppTitle "CHAT CLIENT"

;the channel stream that will be assigned from the server once connected.
Global client_stream

;const for keyboard space and esc keys
Const k_space = 57
Const k_esc = 1

;ask for a nickname
client_id$ = Input$("Enter your nickname: ")

;if no nickame then end
If client_id$ = "" Then End

;attempts to open a socket (stream) on the remote server, with the default port = port
;========= ATTENTION ========================
;here the IP address should be the one of the server !!!
;right now this value is just to allow testing on a local machine. Prompt the user to
;type in the right ip address, if you want a remote connection !!!
strmClient=OpenTCPStream("127.0.0.1",port)

;checks if the stream connection was successfully estabilished
If strmClient<>0 Then 
Print "Client successfully connected"
Else
Print "Server failed to connect - quitting."
WaitKey 
End
End If


;first, write the client nickname to the server
msg$ = "UID" + client_id$
WriteLine strmClient,msg$

;until ESC is pressed
While Not KeyDown(k_esc)

;if space bar pressed, then input a message
If KeyDown(k_space)
	
	;waits until space bar is released
	While KeyDown(k_space)
	Wend

	;ask for a message to send
	message$ = Input$("Your message: ")
			
	;writes the message on the stream channel - that is, sends a message to the server
	msg$ =	"MSG" + message$	
	WriteLine strmClient, msg$
EndIf

;listen for incoming messages

;if a message is queued then retrieves it
If ReadAvail (strmClient)  Then

	;gets the message
	message$ = ReadLine$ (strmClient)
		
	;checks if is a message from the server
	If Mid$(message$,1,3) = "SRV" Then
		
		;select the second part of the header
		what$ = Mid$(message$,4,3)
		Select what$
		
			Case "_ID"
				;the server has sent this client unique ID stream
				client_stream = Mid$(message$,7)
				;Print "client_stream = " + client_stream
			
			Case "BYE"
				;server disconnected !
				Color 255,0,0
				Print " - The server has disconnected - press esc key to quit - "
				Color 255,255,255
				
			Default
				;unknown message
				Print " - Unknown message from the server - "
		
		End Select
		
	Else
		;it's a simple broadcast message
		;prints in red color a disconnection message
		If Instr(Upper(message$),Upper("disconnected")) Then
			Color 255,0,0
		EndIf
		
		;shows the message	
		Print "<" + message$ + ">"
		Color 255,255,255
				
	EndIf
	
EndIf

;small delay
Delay 30

Wend

;logging out from server
msg$ = "ESC" + client_stream
WriteLine strmClient,msg$
Delay 30

End

;========== SERVER CODE ==================
;TCP SERVER program
;by Sergio Marcello
;semar63@hotmail.com
;www.sergiomarcello.com

Graphics 640,480,16,3 ;windowed scaled mode

;sets the title of the application
AppTitle "CHAT SERVER"

Global received_stream
Const k_space = 57
Const k_esc = 1

;creates a type of client with two items: client name, and client ID stream
Type client
	Field uid$
	Field stream
End Type

;declare a global type variable for the client
Global c.client

;sets the port where to listen from, and where the client can connect to.
port = 40000 ;was 1024, but sometime is used by nowadays pc.


;Create a server and listen for client connections
svrGame=CreateTCPServer(port)

;checks if the server was successfully created; if not, ends the program
If svrGame<>0 Then 
Print "Server started successfully - listening on port " + port
Else
Print "Server failed to start on port " + port
End
End If

;=====================================================================

;Main loop until ESC is pressed
While Not KeyDown(k_esc)
message$ = ""

;checks if there is a NEW client connection
strStream=AcceptTCPStream(svrGame)

If strStream Then ;a new client has joined the chat; his ID stream is strStream

;memorize the current connection stream
received_stream = strStream

;reads info from the client just connected (see tcp_client.bb)
If ReadAvail(strStream) Then
message$ =  ReadLine$(strStream)
EndIf

Else 

;there are NOT new connections; so checks if there are incoming data from clients
For c.client = Each client
If ReadAvail(c\stream) Then
	;Print "incoming message from client: " + c\UID
	received_stream = c\stream
	the_user$ = c\uid$
	message$ =  ReadLine$(c\stream)
	Exit
EndIf
Next


EndIf


If message$ <> "" Then ;a message has arrived, or a new client has joined the chat

	;processes the data from the client:

	;checks the header of the message
	header$ = Mid$(message$,1,3)
	
	;tests the header
	Select 	header$
	
	Case "UID" ;it's a NEW client connection
		
		;extracts the user ID
		the_user$ = Mid$(message$,4)
		
		;creates a new client type structure and memorize userid and stream number
		c.client = New client
		c\uid = the_user$
		c\stream = strstream
		
		;notifyes to the client his stream number
		WriteLine c\stream, "SRV_ID" + c\stream
				
		;broadcasts the new client connection
		msg_new$ = "<" + the_user$ + "> connected !"
		notify_message(msg_new$)
		
	Case "MSG" ;it's a message from a client
		

		;broadcasts the user message
		msg_new$ = "<" + the_user$ + ">  " + Mid$(message,4)
		notify_message(msg_new$)
		
	Case "ESC";a client has disconnected from the chat
	
		;extracts the client ID stream that was sent from the client in the message
		client_stream = Mid(message$,4)
	
		;locate the client name from the list of the client
		For c.client = Each client
			
			If c\stream = client_stream Then
				
				;retrieve the client id
				the_user$ = c\uid	
				
				;delete the client
				Delete c
				
				;exit for
				Exit
			EndIf
		Next

		;broadcasts the message
		msg_new$ = "<" + the_user$ + ">  Disconnected"
		notify_message(msg_new$)
		
	End Select

	;small pause
	Delay 20
	
EndIf

;if space bar pressed, then input a message
If KeyDown(k_space)
	
	;waits until space bar is released
	While KeyDown(k_space)
	Wend

	;ask for a message to send
	message$ = Input$("Your message: ")
			
	;prepare the message to be sent
	msg_new$ =	"<server> " + message$
	
	;broadcasts the message
	notify_message(msg_new$)
	
EndIf



Wend

;quitting
;sends a logoff message to all the client
notify_message("SRVBYE")
Delay 20

End

;===============================
Function notify_message(msg_new$)
;===============================

;notifyes the message on the server itself
If Instr(Upper(msg_new$),Upper("disconnected")) Then
	Color 255,0,0
EndIf

;shows only client messages
If received_stream <> 0 Then
	Print msg_new$
EndIf

Color 255,255,255

;notifyes the message to all the logged clients, but the sender
c.client = First client
For c.client = Each client
	If c\stream <> received_stream Then
		WriteLine c\stream,msg_new$
	EndIf
Next

received_stream = 0

End Function