global _start

; constants
SYS_READ        equ 0
SYS_WRITE       equ 1
SYS_SENDFILE    equ 40
SYS_SOCKET      equ 41
SYS_ACCEPT      equ 43
SYS_BIND        equ 49
SYS_LISTEN      equ 50
SYS_EXIT        equ 60
SYS_FCNTL       equ 72
SYS_UNLINK      equ 87
STDOUT          equ 1
AF_UNIX         equ 1
SOCK_STREAM     equ 1
F_GETFL         equ 3
F_SETFL         equ 4
O_NONBLOCK      equ 2048

SECTION .data
hello           db "Hello world!", 0x0a
hello_len       equ $ - hello
server_path     db "server.sock", 0x00
server_path_len equ $ - hello
sockaddr_len    equ 110 ; $ man 7 unix

SECTION .bss
sockaddr    resb sockaddr_len

SECTION .text

_start:
    mov rax, SYS_WRITE
    mov rdi, STDOUT
    mov rsi, hello
    mov rdx, hello_len
    syscall

    call make_server
    push rax
    call accept
    pop r10

exit:
    mov rax, SYS_EXIT
    mov rdi, 0
    syscall

accept:
    mov rdi, rax
    mov rax, SYS_ACCEPT
    mov rsi, 0
    mov rdx, 0
    syscall
    ret

make_server:
    mov rax, SYS_UNLINK
    mov rdi, server_path
    syscall

    mov rax, SYS_SOCKET
    mov rdi, AF_UNIX
    mov rsi, SOCK_STREAM
    mov rdx, 0
    syscall
    push rax

    call nonblocking
    call make_sockaddr
    pop r10

    mov rax, SYS_BIND
    mov rdi, r10
    mov rsi, sockaddr
    mov rdx, sockaddr_len
    syscall

    mov rax, SYS_LISTEN
    mov rdi, r10
    mov rsi, 100
    syscall

    mov rax, r10
    ret

nonblocking:
    mov r10, rax

    mov rax, SYS_FCNTL
    mov rdi, r10
    mov rsi, F_GETFL
    syscall

    mov r11, rax
    xor r11, O_NONBLOCK

    mov rax, SYS_FCNTL
    mov rdi, r10
    mov rsi, F_SETFL
    mov rdx, r11
    syscall

    ret

make_sockaddr:
    mov word [sockaddr], AF_UNIX
    mov rax, 0

make_sockaddr__copy_server_path:
    cmp rax, server_path_len
    jge return
    mov r10, [rax+server_path]
    add rax, 2
    mov [rax+sockaddr], r10
    sub rax, 1
    jmp make_sockaddr__copy_server_path

return:
    ret