[bb] UDP Scanner by semar [ 1+ years ago ]

Started by BlitzBot, June 29, 2017, 00:28:39

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June 29, 2017, 00:28:39
Title : UDP Scanner
Author : semar
Posted : 1+ years ago

Description : Due to popular demand, I post here the code of my UDP scanner.

This code will scan an entire LAN for a server on a specific port, by using a broadcast IP address.

No need to know the server IP address to join, broadcast messages will be delivered to all the active IP address on the LAN - very useful.

The code here is a complete test program, but you need only some functions to suit your needs.

To test the program, open the source with any Blitz IDE and run two or three sessions. Or even better, try it in a LAN.

I use this code in my game BomberLAN, which can be found on my website www.sergiomarcello.com

Code :
Code (blitzbasic) Select
;UDP Scanner - by Sergio Marcello - www.sergiomarcello.com - semar63@hotmail.com
;read config p_in e p_out
Global IN_PORT = 50000
Global OUT_PORT = 50001
Global BRO_PORT = 50000
Global local_ip$
Global local_ip_int
Global Broadcast_IP%
Global STREAM_R ;receive stream
Global STREAM_W ;write stream
Global Player_Num = 0
Global IAmServer = False
Global DEBUG
Global pcName$

Global STATUS = 0
Const STA_WAIT = 3
Const STA_SYNC = 4


Type t_client
Field IP
Field Port
Field player_ID
Field joined
Field pcName$
End Type
Global client.t_client

;==================== 1
If CommandLine$() = "test" Then
DEBUG = True
EndIf

Print "-------------------------------"
Print "--- UDP Scanner V. 2.0 Beta ---"
Print "-------------------------------"
Print

Get_Local_IP()
Print

If Not Open_Streams() Then
WaitKey
End
EndIf


;==================== 2

Broadcast_IP = Get_Broadcast_IP()

;loop
Local finito
Local starttime
Local msg$

If IN_PORT = 50000 Then
If DEBUG Then
IAmServer = True
EndIf
EndIf

finito = False

While Not finito

If KeyHit(1) Then
End
EndIf

;broadcast every sec
If ((MilliSecs() - starttime) >= 3000) Then
starttime = MilliSecs()
Broadcast("PING")
EndIf

;get msg
Local IP_check = RecvUDPMsg (STREAM_R)
If IP_check <> 0 Then

Local Port_Check = UDPMsgPort(STREAM_R)

;if extern msg then
If Extern_Message(IP_Check,Port_Check) Then

;read msg
msg$ = ReadString(stream_R)

DebugLog.Print "ext: " + msg$ + " from IP " + IP_Check + " on port " + port_check

Select Mid$(msg$,1,4)

Case  "PING"

If Not IAmServer Then
;found a server
Print "found server on port = " + Port_Check

;add server to list
;client.t_client = New t_client
;clientip = IP_Check
;clientport = Port_Check
;clientplayer_ID = 1 ;server
;clientjoined = True

;send pong
WriteString(stream_R,"PONG#" + pcName$)
SendUDPMsg stream_R,IP_Check,Port_Check
;

status = STA_WAIT
;finito = True
Exit ;exit while loop
Else
;send a PING back
WriteString(stream_R,"PING")
SendUDPMsg stream_R,IP_Check,Port_Check
EndIf


Case "PONG"

Local name$ = Mid$(msg$,6)
Print "new player: " + name$ + " on port = " + Port_Check
player_num = player_num + 1

;if I'm not yet in the list
If player_num = 1 Then
;add me as a server to list
client.t_client = New t_client
clientip = local_ip_int
clientport = IN_PORT
clientplayer_ID = 1 ;server
clientjoined = True
clientpcName$ = pcName$
player_num = player_num + 1
IAmServer = True
EndIf

;add client to list
client.t_client = New t_client
clientip = IP_Check
clientport = Port_Check
clientplayer_ID = player_num ;client
clientjoined = True
clientpcName$ = name$


;pause ?

;send all clients info
send_client_info()


;end case
End Select


Else ;internal message

DebugLog.Print "intern: <" + msg$ + "> from IP " + IP_Check + " on port " + port_check

;endif
EndIf ;if extern message

;if enter then
If KeyHit(28) Then
status = STA_SYNC
Exit
EndIf
;status = sync
;endif



EndIf ;if message



Wend
;

;==================== 3 WAIT
If status = STA_WAIT Then
Wait_Sync()
EndIf

;==================== 4 SYNC
If status = STA_SYNC Then
Print "sync..."
;Send_Sync()
Delay 100
If DEBUG Then
For c.t_client = Each t_client
WriteString(stream_R,"SYNC")
SendUDPMsg stream_R, cIP, cPort
Next

Else
Broadcast("SYNC")
EndIf
EndIf



WaitKey
End

;============================================
Function Wait_Sync()
;============================================
Local msg$
Local cmd$
Local starttime
Print "waiting sync..."

While 1
;read msg every 50 msec
If ((MilliSecs() - starttime) >= 50) Then

;get msg
Local IP_check = RecvUDPMsg (STREAM_R)
If IP_check <> 0 Then

Local Port_Check = UDPMsgPort(STREAM_R)

;if extern msg then
If Extern_Message(IP_Check,Port_Check) Then

;read msg
msg$ = ReadString(stream_R)

cmd$ = Mid$(msg$,1,4)

Select cmd$
Case "LIST"
Get_Client(msg$)
Print msg$

Case "SYNC"
End
End Select

Else

;intern message
DebugLog.Print "intern:<" + msg$ + "> from IP " + IP_Check + " on port " + port_check

EndIf

EndIf

starttime = MilliSecs()

EndIf

If KeyHit(1) Then
End
EndIf

Wend

End Function

;============================================
Function Extern_Message(IP_Check,Port_Check)
;============================================
;consider only the broadcast that comes from other client

If DEBUG Then
extern_msg = ((Str$(IP_Check) + Str$(Port_Check)) <> (Str$(Broadcast_IP) + Str$(IN_PORT)))
;extern_msg = extern_msg And (((Str$(IP_Check) + Str$(Port_Check)) <> (Str$(local_ip_int) + Str$(IN_PORT))))
Else
extern_msg = (IP_check <> local_ip_int)
EndIf

Return extern_msg

End Function

;============================================
Function send_client_info()
;============================================
;send client info to all the clients
Local msg$
;For c.t_client = Each t_client

; If cip <> local_ip_int Then
; msg = msg + "#" + cIP + "#" + cport
; EndIf

;Next

For a.t_client = Each t_client

If aip <> local_ip_int Then

For c.t_client = Each t_client


msg$ = "LIST#" + cpcName$ + "#" + cplayer_id + "#" + cIP + "#" + cport
WriteString(stream_R,msg$)
SendUDPMsg stream_R, aIP, aPort
Delay 50

DebugLog.Print "lista---------"
DebugLog.Print msg$
DebugLog.Print "ip= " + aip
DebugLog.Print aport
DebugLog.Print "------------"

Next

EndIf

Next

;broadcast ?
;SendUDPMsg stream_W,IP_BROADCAST,IN_PORT
End Function

;===========================
Function Broadcast(msg$)
;===========================

WriteString(STREAM_R,msg$)
SendUDPMsg STREAM_R, Broadcast_IP, BRO_PORT
DebugLog.Print "Broadcast: " + msg + " to IP: " +  Broadcast_IP + " on port: " + BRO_PORT

End Function


;===========================
Function Open_Streams()
;===========================

STREAM_R = CreateUDPStream(IN_PORT) ; Read Stream
If Not DEBUG Then
If Not STREAM_R Then
Print "Unable to open input stream on port " + IN_PORT
Print
Print "please edit the config file on all clients and"
Print "change the in and out port to other values."
Print "if running behind a firewall, you may need"
Print "to disable it."
Return False
EndIf
EndIf

While Not STREAM_R
IN_PORT = IN_PORT + 1
If IN_PORT > 65536 Then
Print "Unable to open input stream on port " + IN_PORT
Return False
EndIf
STREAM_R = CreateUDPStream(IN_PORT)
Wend

STREAM_W = CreateUDPStream(OUT_PORT) ; Write Stream
While Not STREAM_W
OUT_PORT = OUT_PORT + 1
If OUT_PORT > 65536 Then
Print "Unable to open output stream on port " + OUT_PORT
Return False
EndIf
STREAM_W = CreateUDPStream(OUT_PORT)
Wend


Print "Stream on port" + IN_PORT  +  " successfully opened"
Print "Stream on port" + OUT_PORT + " successfully opened"

Return True

End Function
;===========================


;===========================
Function Get_Local_Ip()
;===========================
;Print "Computer name: " + GetEnv$("COMPUTERNAME")
;Print "User Domain:   " + GetEnv$("USERDOMAIN")
;Print "User name:     " + GetEnv$("USERNAME")
pcName$ = GetEnv$("COMPUTERNAME") + "/" + GetEnv$("USERNAME")
pcName$ = Replace (pcName$,"#","_")
pcName$ = Mid$(pcName$,1,10)
Print "pc name = " + pcName$



;enumerate all the IP on this local pc
ip_count=CountHostIPs(GetEnv("localhost"))

Print "IP address count: " + ip_count
Print

For i = 1 To ip_count

local_ip_int = HostIP(i)
    local_ip$ = DottedIP(HostIP(i))
Print i + "   " + local_ip$ + " <" + local_ip_int + ">"

;if debugging, will take the local address
If DEBUG Then
If (Instr(local_ip$,"127.0")) Then
Print
Print "* * * * * * Debug mode * * * * * * "
Exit
EndIf
Else
If (Instr(local_ip$,"192.168")) Then
Exit
EndIf
EndIf
;If (Not Instr(local_ip,"192.168")) Then
;If (Not Instr(local_ip,"127.0")) Then
; Exit
;EndIf
Next

End Function

;===========================
Function Get_Broadcast_IP()
;===========================
;build the broadcast IP; it is made by the ip address, only the third triplet is 255
Local point = 1

For n = 1 To 3
point = Instr(local_ip$,".",point)
point = point + 1
Next
point = point - 1 ;now point is the position of the third "." in the IP address
Local broadcast$ = Mid$(local_ip$,1,point) + "255"
Local IP_broadcast% = Int_IP(broadcast$)

Print "Broadcast IP = " + Broadcast$ + " <" + IP_Broadcast% + ">"
Return IP_Broadcast%

End Function

;============================================
Function Int_IP(IP$)
;============================================
;convert a string formatted IP address to an integer value
a1=val(Left(IP$,Instr(IP$,".")-1)):IP$=Right(IP$,Len(IP$)-Instr(IP$,"."))
a2=val(Left(IP$,Instr(IP$,".")-1)):IP$=Right(IP$,Len(IP$)-Instr(IP$,"."))
a3=val(Left(IP$,Instr(IP$,".")-1)):IP$=Right(IP$,Len(IP$)-Instr(IP$,"."))
a4=val(IP$)
Return (a1 Shl 24) + (a2 Shl 16) + (a3 Shl 8 ) +a4
End Function

;============================================
Function val(String$)
;============================================
; Returns integer value of a string
ac=String$
Return String$
End Function

;============================================
Function Get_Client(msg$)
;============================================
;retrieve the new joined client

;the message is usually like: << LIST#ID#IP#PORT >>  ID, IP and PORT are all numeric values.
Local p
Local id
Local ip
Local port
Local name$

msg$ = Mid$(msg$,6)

;get pcname
p = Instr(msg$,"#")
name$ = Mid$(msg$,1,p-1)

;get player id
msg$ = Mid$(msg$,p+1)
p = Instr(msg$,"#")
id = Int(Mid$(msg$,1,p-1))

;get ip
msg$ = Mid$(msg,p+1)
p = Instr(msg$,"#")
ip = Int(Mid$(msg$,1,p-1))

;get port
msg$ = Mid$(msg$,p+1)
port = Int(msg$)

If Not (ListContains(id)) Then
;add the new client
client.t_client = New t_client
clientip = ip
clientport = port
clientplayer_ID = id
clientjoined = True ;joined
clientpcName$ = name$
Print "New player: " + name$ + ", " + id + ", " + ip + ", " + port
;Text 0,yy, "New Player: " + NewIP + ", " + NewPort
;yy = yy + dy
EndIf

End Function

;==================================
Function ListContains(id)
;==================================
For c.t_client = Each t_client
If cplayer_ID = id Then
Return True
EndIf
Next
End Function

Comments :


Nate the Great(Posted 1+ years ago)

 thanks a million.  And it seems like a lot of the networking commands arent in the docs at all... odd


_PJ_(Posted 1+ years ago)

 This is very handy, thanks, Semar.Nate - what commands are you revferring to, I had a browse through but all the ones I looked for were in the native docs. You sure you have updated your docs pack?


Heliotrope(Posted 1+ years ago)

 is Broadcast in row 74 a comand?


semar(Posted 1+ years ago)

 @mark1110,Broadcast in row 74 is not a command, rather a function. Do a search in the code for "Function Broadcast" and you'll find it.
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