Sockets
socket
Syscall 41 (socket) creates a socket. Arguments: domain (AF_INET = 2), type (SOCK_STREAM = 1), protocol (0 for TCP). The descriptor comes back in RAX:
%define SYS_SOCKET 41
mov rax, SYS_SOCKET
mov rdi, 2 ; AF_INET
mov rsi, 1 ; SOCK_STREAM
xor rdx, rdx ; protocol 0
syscall
bind and listen
Syscall 49 (bind) takes the descriptor, a pointer to a sockaddr_in struct, and its length (16). Syscall 50 (listen) marks the socket as a listening socket with a backlog count:
%define SYS_BIND 49
%define SYS_LISTEN 50
mov rax, SYS_BIND
mov rdi, fd
mov rsi, addr ; sockaddr_in
mov rdx, 16
syscall
mov rax, SYS_LISTEN
mov rdi, fd
mov rsi, 10 ; backlog
syscall
accept
Syscall 43 (accept) waits for a connection and returns a new descriptor for it. The sockaddr and length arguments can be NULL. From there, read (0) and write (1) work on the connection descriptor like a file.
Next: A tiny HTTP client
Article author: Arthur Isaev
