/* A simple server in the internet domain using TCP
   The port number is passed as an argument */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
    int sockfd, newsockfd, portno;
    socklen_t clilen;
    char buffer[256];
    struct sockaddr_in serv_addr, cli_addr;
    int n;
    int opt=1;

    if (argc < 2) {
        error("ERROR, no port provided\n");
        exit(1);
    }
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
       error("ERROR opening socket");

    bzero((char *) &serv_addr, sizeof(serv_addr));
    portno = atoi(argv[1]);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);
    setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,(const char *)&opt,sizeof(int));
    if (bind(sockfd, (struct sockaddr *) &serv_addr,
            sizeof(serv_addr)) < 0)
        error("ERROR on binding");
    listen(sockfd,5);
    clilen = sizeof(cli_addr);

    // Waits here
    newsockfd = accept(sockfd,
                (struct sockaddr *) &cli_addr,
                &clilen);
    if (newsockfd < 0)
        error("ERROR on accept");
    bzero(buffer,256);
    n = read(newsockfd, buffer, 255);
    if (n < 0) error("ERROR reading from socket");

    printf("Server Buffer: %s\n", buffer);
    
    char *str = "I got your message!";

    // Returns a confirmation message
    n = write(newsockfd, str, strlen(str)+1);
    if (n < 0) error("ERROR writing to socket");
    close(newsockfd);
    close(sockfd);
    return 0;
}
