simple_socket_setup.c

#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>

#ifndef fatal
#define fatal(msg) \
    do { fprintf(stderr, "[FATAL]: %s:%i: %s: %s\n", __func__, __LINE__, msg, strerror(errno)); exit(EXIT_FAILURE); } while (0)
#endif

int create_bound_socket(const sa_family_t domain, const int protocol, const char* ip, const char* port) {
    struct addrinfo hints = {0};
    hints.ai_family = domain;
    hints.ai_socktype = protocol;
    if (!ip)
        hints.ai_flags = AI_PASSIVE;

    struct addrinfo* result;

    int status = getaddrinfo(ip, port, &hints, &result);
    if (status != 0) {
        fprintf(stderr, "getaddrinfo error: %s\n", gai_strerror(status));
        exit(EXIT_FAILURE);
    }

    int socket_fd = -1;
    struct addrinfo* rp;
    for (rp = result; rp != NULL; rp = rp->ai_next) {
        socket_fd = socket(rp->ai_family, rp->ai_socktype | SOCK_NONBLOCK, rp->ai_protocol);
        if (socket_fd == -1)
            continue;

        int reuse = true;
        if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) == -1)
            continue;

        if (setsockopt(socket_fd, SOL_SOCKET, SO_REUSEPORT, &reuse, sizeof(reuse)) == -1)
            continue;

        struct linger linger = {1, 1};
        if (setsockopt(socket_fd, SOL_SOCKET, SO_LINGER, &linger, sizeof(linger)) == -1)
            continue;

        if (rp->ai_protocol == SOCK_STREAM) {
            int keepalive = true;
            if (setsockopt(socket_fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof(keepalive)) == -1)
                continue;
        }

        if (bind(socket_fd, rp->ai_addr, rp->ai_addrlen) == 0)
            break;                  /* Success */

        close(socket_fd);
    }

    if (rp == NULL) {               /* No address succeeded */
        fatal("Could not bind");
    }

    freeaddrinfo(result);           /* No longer needed */

    if (protocol == SOCK_STREAM || protocol == SOCK_SEQPACKET) {
        if (listen(socket_fd, 64) == -1)
            fatal("listen");
    }

    return socket_fd;
}