#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>

#define QLEN 10
#define BUFFSIZE 500

void urg_handler(int);

    /* must be global so I can recv from handler */
    int                 new_sd;
    struct timeval      tv;

int main(int argc, char *argv[]) {
    struct sockaddr_in  my_sin;
    struct sockaddr_in  their_sin;
    struct sigaction    sa;
    unsigned short      port;
    int                 sd;
    int                 bytes_read;
    int                 sin_size;
    char                buff[BUFFSIZE];
    fd_set              rfds;

    if (argc != 2 || !((port = atoi(argv[1])) > 0)) {
        fprintf(stderr, "usage: %s port\n", argv[0]);
        exit(1);
    }

    sd = socket(AF_INET, SOCK_STREAM, 0);
    if (sd == -1) {
        perror("socket");
        exit(1);
    }

    memset(&my_sin, 0, sizeof(struct sockaddr_in));
    my_sin.sin_family = AF_INET;
    my_sin.sin_port = htons(port);
    my_sin.sin_addr.s_addr = INADDR_ANY;

    if (bind(sd, (struct sockaddr *)&my_sin, sizeof(my_sin)) == -1) {
        perror("bind");
        exit(1);
    }

    if (listen(sd, QLEN) == -1) {
        perror("listen");
        exit(1);
    }

    printf("server: listening on port %d\n", port);

    sa.sa_handler = urg_handler;
    sa.sa_flags = SA_RESTART;
    sigemptyset(&(sa.sa_mask));
    sigaction(SIGURG, &sa, NULL);


    while(1) {
        sin_size = sizeof(their_sin);
        printf("server: waiting for connection...");
        fflush(stdout);

        new_sd = accept(sd, (struct sockaddr *)&their_sin, &sin_size);

        if (new_sd < 0) {
            perror("accept");
            exit(1);
        }

        if (fcntl(new_sd, F_SETOWN, getpid()) == -1) {
            perror("fcntl");
            exit(1);
        }

        printf("\nserver: got a connection from %s\n", 
            inet_ntoa(their_sin.sin_addr));

        bytes_read = 1;
        FD_ZERO(&rfds);
        tv.tv_sec = 20;
        tv.tv_usec = 0;

        while (bytes_read) {
            FD_SET(new_sd, &rfds);
            if (!select(new_sd + 1, &rfds, NULL, NULL, &tv)) {
                bytes_read = 0;
                printf("server: client timed out after 20 seconds\n");
            } else {
                bytes_read = recv(new_sd, buff, BUFFSIZE, 0);
                if (bytes_read) {
                    buff[bytes_read] = '\0';
                    printf("server: read %d bytes, \"%s\"\n", bytes_read, buff);
                } else {
                    printf("server: remote side closed connection\n");
                }
            }
        }

        close(new_sd);
    }

    return 0;
}


void urg_handler(int signo) {
    char    buff[BUFFSIZE];
    int     bytes_read;

    /* funky stuff happening here! */
    tv.tv_sec = 20;
    tv.tv_usec = 0;

    bytes_read = recv(new_sd, buff, BUFFSIZE, MSG_OOB);
    buff[bytes_read] = '\0';
    printf("server: read %d byte(s) of OOB data, \"%s\"\n",
        bytes_read, buff);
}