mysever.c

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>

#include <netinet/in.h>
#include <ctype.h>
#include <arpa/inet.h>

#include <fcntl.h>
#include <netdb.h>

#include <string.h>
#include <strings.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#define MAXFD 2

int main(int argc, char ** argv)
{
    int sockfd, newsockfd, portno; // clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    socklen_t clilen;
    int n;
    char * c;//

    if (argc < 3)
    {
        fprintf(stderr, "usage: %s ip port\n", argv[0]);
        return 0;
    }

    /* Create TCP socket */
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
    {
        perror("ERROR opening socket");
        exit(EXIT_FAILURE);
    }

    // reuse the socket if possible
    int const reuse = 1;
    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(int)) < 0)
    {
        perror("setsockopt");
        exit(EXIT_FAILURE);
    }

    portno = atoi(argv[2]);

    /* Create address we're going to listen on (given port number)
     - converted to network byte order & any IP address for this machine */
    bzero((char *)&serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;//differ
    serv_addr.sin_port = htons(portno); // store in machine-neutral format

    /* Bind address to the socket */
    if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
    {
        perror("ERROR on binding");
        exit(EXIT_FAILURE);
    }

    /* Listen on socket - means we're ready to accept connections -
     incoming connection requests will be queued */
    listen(sockfd, 5);