#define _GNU_SOURCE
#include <arpa/inet.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/ip.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <poll.h>
#include <unistd.h>

int main(void)
{
    const struct sockaddr_in connect_addr = {.sin_family = AF_INET, .sin_addr = htonl(INADDR_LOOPBACK), .sin_port = htons(9374)};
    int buffer_size = 1024 * 1024;
    int listener, server, client, ret, error;
    struct sockaddr_in addr = {0};
    struct linger linger;
    struct pollfd pollfd;
    unsigned int i;
    pthread_t thread;
    socklen_t len;
    char *buffer = malloc(buffer_size);

    listener = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    client = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

    ret = getsockname(listener, (struct sockaddr *)&addr, &len);
    printf("getsockname -> %d, {%u, %#x}, %s\n", ret, addr.sin_family, addr.sin_addr.s_addr, strerror(errno));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    ret = bind(listener, (struct sockaddr *)&addr, sizeof(addr));
    if (ret < 0)
        printf("bind -> %d, %s\n", ret, strerror(errno));
    len = sizeof(addr);
    ret = getsockname(listener, (struct sockaddr *)&addr, &len);
    if (ret < 0)
        printf("getsockname -> %d, %s\n", ret, strerror(errno));
    ret = listen(listener, 1);
    if (ret < 0)
        printf("listen -> %d, %s\n", ret, strerror(errno));

    ret = connect(client, &addr, sizeof(addr));
    if (ret < 0)
        printf("connect -> %d, %s\n", ret, strerror(errno));

    server = accept4(listener, (struct sockaddr *)&addr, &len, SOCK_NONBLOCK);
    if (server < 0)
        printf("accept -> %d, %s\n", server, strerror(errno));

    ret = send(client, "A", 1, MSG_OOB);
    if (ret != 1)
        printf("send -> %d, %s\n", ret, strerror(errno));

    ret = recv(server, buffer, buffer_size, MSG_OOB);
    if (ret != 1)
        printf("recv -> %d, %s\n", ret, strerror(errno));

    if (0)
    {
    ret = recv(server, buffer, buffer_size, 0);
    if (ret != 1)
        printf("recv #3 -> %d, %s\n", ret, strerror(errno));
    }

    pollfd.fd = server;
    pollfd.events = POLLIN | POLLPRI;
    ret = poll(&pollfd, 1, 0);
    printf("poll -> %d, %#x\n", ret, pollfd.revents);

    ret = 1;
    ret = setsockopt(server, SOL_SOCKET, SO_OOBINLINE, &ret, sizeof(ret));
    if (ret < 0)
        printf("setsockopt -> %d, %s\n", ret, strerror(errno));

    pollfd.fd = server;
    pollfd.events = POLLIN | POLLPRI;
    ret = poll(&pollfd, 1, 0);
    printf("poll -> %d, %#x\n", ret, pollfd.revents);

    ret = recv(server, buffer, buffer_size, 0);
    if (ret != 1)
        printf("recv #3 -> %d, %s\n", ret, strerror(errno));

    return 0;
}