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

#define serverport 8000
#define httpanswer "HTTP/1.1 200 OK\nContent-Type: text/html\n\nHello World\n"

int main (int argc, const char * argv[]) 
{
    int e;
    
    printf("First, open a socket.\n");
    int handle=socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    printf("socket handle %d \n",handle);

    printf("Second, bind to port.\n");
    struct sockaddr_in a;
    bzero(&a, sizeof(a)); // clear structure
    a.sin_family=AF_INET;
    a.sin_addr.s_addr=INADDR_ANY;
    a.sin_port=serverport;
    
    e=bind(handle, (struct sockaddr*)&a, sizeof(a));
    printf("result from bind: %d \n",e);
    
    printf("Third, listen for an incoming connection.\n");
    e=listen(handle, 5); // 5 items in waiting quere
    printf("result from listen: %d \n",e);
    
    if (e>=0) // success
        {
        
        struct sockaddr_in cli_addr;
        int clilen=sizeof(cli_addr);
        int sock=accept(handle, (struct sockaddr*) &cli_addr, &clilen);
        
        printf("second socket handle %d \n",sock);
        
        printf("Read request.\n");
       
        char buf[5000];
        e=read(sock, buf, sizeof(buf));
        if (e>0)
            {
            buf[e]=0; // end mark
            printf("%s \n",buf);
            }
        printf("Send answer.\n");
        e=write(sock, httpanswer, strlen(httpanswer));
        printf("result from write: %d \n",e);

        
        close(sock);
        }
    
    e=close(handle);
    printf("result from close: %d \n",e);
    
    return 0;
}