Network

IPv4 socket helpers for listening over TCP and binding over UDP. You are responsible for accepting connections, sending and receiving data, and closing sockets.

Usage

Create a listening socket with lf_listen_tcp(). Pass NULL as the host to bind to all local IPv4 interfaces. Port "0" lets the kernel choose a port; use getsockname() to read it back.

int fd = lf_listen_tcp("127.0.0.1", "8080");
if (fd >= 0) {
    int client = accept(fd, NULL, NULL);
    if (client >= 0) {
        /* Exchange data with the client. */
        lf_close(client);
    }
    lf_close(fd);
}

accept() blocks until a connection arrives or an error occurs. The returned sockets are yours to close.

Functions

lf_listen_tcp

Creates an IPv4 TCP socket, binds it, and starts listening. Returns the socket descriptor, or -1 on error. port must be non-NULL.

int lf_listen_tcp(const char *host, const char *port);

lf_bind_udp

Creates an IPv4 UDP socket and binds it. Returns the socket descriptor, or -1 on error. The host and port rules are the same as lf_listen_tcp().

int lf_bind_udp(const char *host, const char *port);

lf_close

Closes fd if it is nonnegative. A negative descriptor does nothing.

void lf_close(int fd);

get_in_addr

Returns a pointer to the IPv4 or IPv6 address inside sa. The pointer borrows storage from sa. Returns NULL if sa is NULL or has an unsupported address family. This helper accepts IPv6 addresses even though the bind helpers only create IPv4 sockets.

void *get_in_addr(struct sockaddr *sa);