Winsock Send Help.

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Overflowz

Joined: 03 Sep 2010
Posts: 1046

Overflowz 10 Sep 2010, 13:14

Hello everyone. I have problem about send command from winsock.. It dont sends nothing just closes itself this is code and tell me what I'm doing wrong.. Thanks.

Code:

format PE console 4.0
entry main
include 'WIN32AX.INC'
.data
server dd ?
welcome db "Hi",0
saddrlen dd sizeof.sockaddr_in
saddr sockaddr_in
wsaData WSADATA
PORT = 23
.code
main:
invoke WSAStartup,0202h,wsaData
invoke WSASocket, AF_INET, SOCK_STREAM, 6, 0, 0, 0
mov [server], eax
mov [saddr.sin_family], AF_INET
invoke htons, PORT
mov [saddr.sin_port], ax
invoke htonl, 0
mov [saddr.sin_addr], eax
invoke bind, [server], saddr, saddrlen
invoke listen, [server], 1
invoke accept, [server], saddr, saddrlen
invoke send,[server],welcome,2,0
invoke ExitProcess,0
data import
library kernel32,'kernel32.dll',ws2_32,'ws2_32.dll'
include 'API\KERNEL32.INC'
include 'API\WS2_32.INC'
end data

10 Sep 2010, 13:14

Picnic

Joined: 05 May 2007
Posts: 1403
Location: Piraeus, Greece

Picnic 10 Sep 2010, 14:29

Hi,

If accept() succeeds, the return value is a new socket created on the server side.
therefore it would be better:

Code:

invoke accept, [server], saddr, saddrlen
mov [client],eax
invoke send,[client],welcome,2,0

Close sockets and cleanup. Code should work now.

closesocket()
WSACleanup()

10 Sep 2010, 14:29

Nameless

Joined: 30 Apr 2010
Posts: 95

Nameless 10 Sep 2010, 14:37

but i think accept is non-blocking API? am i right? that means it needs to be inside a loop

10 Sep 2010, 14:37

Overflowz

Joined: 03 Sep 2010
Posts: 1046

Overflowz 10 Sep 2010, 14:39

Hi, I understand now whats problem but I have bit problem. when I'm calling WSACleanup, the same problem are occuired. here's code. Thanks.

Code:

format PE console 4.0
entry main
include 'WIN32AX.INC'
.data
server dd ?
client dd ?
welcome db "Hi",0
saddrlen dd sizeof.sockaddr_in
saddr sockaddr_in
wsaData WSADATA
PORT = 23
.code
main:
invoke WSAStartup,0202h,wsaData
invoke WSASocket, AF_INET, SOCK_STREAM, 6, 0, 0, 0
mov [server], eax
mov [saddr.sin_family], AF_INET
invoke htons, PORT
mov [saddr.sin_port], ax
invoke htonl, 0
mov [saddr.sin_addr], eax
invoke bind, [server], saddr, saddrlen
invoke listen, [server], 1
invoke accept, [server], saddr, saddrlen
mov [client],eax
invoke send,[client],welcome,2,0
invoke closesocket,client
invoke closesocket,server
invoke WSACleanup
invoke ExitProcess,0
data import
library kernel32,'kernel32.dll',ws2_32,'ws2_32.dll'
include 'API\KERNEL32.INC'
include 'API\WS2_32.INC'
end data

10 Sep 2010, 14:39

Nameless

Joined: 30 Apr 2010
Posts: 95

Nameless 10 Sep 2010, 15:02

ive nothing to test on here, but its up to u now
here is what i wrote so far

Code:

_data rb      1024

...........

.accept_loop:
    invoke accept, [server], saddr, saddrlen
    cmp     eax, -1
     je      .accept_loop
        mov     [client], eax ;if it reached this line, it means that we have a new connection
      jmp     .recv_loop      ;take that new socket to the receiving loop
 
.recv_loop:
 xor     eax, eax
    mov     dword [_data], eax
  invoke  recv, [client], _data, 1024, 0
      cmp     eax, 0
      je      .end_recv_loop
      ;add one more compare of eax, is its -1, re-initialize all ur sockets again
 jmp     .process_data
               
.end_recv_loop:
    ;Connection Closed, Get Back to listening for new connection
 invoke  closesocket, [client]
       jmp     .accept_loop
                
.process_data:
      ;Process ur data received here

10 Sep 2010, 15:02

Overflowz

Joined: 03 Sep 2010
Posts: 1046

Overflowz 10 Sep 2010, 15:10

Oh Thanks. Smile

BTW I'm trying to figure out how to do like send and recv functions both, like telnet chat ? I know Netcat using that function. with this command nc -L -v -p 23 and when connected I can write something and data are transfered to remote and reverse. How can I do that ? Razz

Thanks.

10 Sep 2010, 15:10

Nameless

Joined: 30 Apr 2010
Posts: 95

Nameless 10 Sep 2010, 15:21

i dont really know what netcat traffic looks like, but here is the simplest way i can think of to process commands

Code:

.process_data: 
        ;Process ur data received here
        invoke StrCmpI, _data, "COMMAND1"
        je .process_command1
        invoke StrCmpI, _data, "COMMAND2"
        je .process_command2
        jmp .recv_loop ;no commands found, re-do the recv loop incase we got something to recoginize

.process_command1:
       ;Do whatever function u want here
       ;and to send()
       invoke send, [client], _data , 1024, 0 ;data or whatever other variable that holds the data u want to send
       jmp  .recv_loop ; must do this after each command, to receive the queued data

.process_command2:
      ;bla bla bla
       jmp      .recv_loop ;exactly as the previous one

StrCmpI

EDIT: oops, forgot to say that the _data is the variable that holds the received data from the connection, as it was done in my previous post

10 Sep 2010, 15:21

Overflowz

Joined: 03 Sep 2010
Posts: 1046

Overflowz 10 Sep 2010, 15:46

Ah I got it. thanks. Smile

And, Is there any other way to do without StrCmpI? I mean without using library. Is that like cmp in asm language ? Smile

10 Sep 2010, 15:46

Picnic

Joined: 05 May 2007
Posts: 1403
Location: Piraeus, Greece

Picnic 10 Sep 2010, 17:30

Overflowz wrote:

Hi, I understand now whats problem but I have bit problem. when I'm calling WSACleanup, the same problem are occuired.

Code:

invoke closesocket,[client]
invoke closesocket,[server]

Nameless wrote:

but i think accept is non-blocking API? am i right? that means it needs to be inside a loop

A socket it is automatically set to be blocking so accept() actually blocks until a connection request comes.

10 Sep 2010, 17:30

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