5_3.cpp

#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<signal.h>
#include<unistd.h>
#include<stdlib.h>
#include<assert.h>
#include<stdio.h>
#include<string.h>

static bool stop = false;

static void handle_term(int sig){ stop = true; }

int main(int argc, char *argv[]){

    signal(SIGTERM, handle_term);

    if(argc <= 3){
        printf("usage: %s ip address port_number backlog\n", basename(argv[0]));
        return 1;
    }

    const char * ip = argv[1];
    int port = atoi(argv[2]);
    int backlog = atoi(argv[3]);

    int sock = socket(PF_INET, SOCK_STREAM, 0);
    assert(sock >= 0);

    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_family = AF_INET;
    inet_pton(AF_INET, ip, &address.sin_addr);
    address.sin_port = htons(port);

    int ret = bind(sock, (struct sockaddr*)&address, sizeof(address));
    assert(ret != -1);

    ret = listen(sock, backlog);
    assert(ret != -1);

    while(!stop){ sleep(1); }

    close(sock);

    return 0;

}