timeserver.c

#include <stdio.h>
#include <string.h>

#ifdef _WIN32
    #include <Windows.h>
#else
    #include <unistd.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <netinet/in.h>
    #include <time.h>
#endif

#define NANO 1000000000LL
#define DMICRO 10000000LL

#ifdef _WIN32
    typedef FILETIME Timer;

    FILETIME start_timer()
    {
        SYSTEMTIME st;
        FILETIME ft;
        GetSystemTime(&st);
        SystemTimeToFileTime(&st, &ft);
        return ft;
    }

    double elapse_timer(FILETIME t0)
    {
        FILETIME t1;
        unsigned long long l0, l1, diff;
        double tdiff;
        t1 = start_timer();
        l0 = t0.dwHighDateTime * NANO + t0.dwLowDateTime;
        l1 = t1.dwHighDateTime * NANO + t1.dwLowDateTime;
        diff = l1 - l0;
        tdiff = (double) (diff % DMICRO) / DMICRO + (double) diff / DMICRO;
        return tdiff;
    }
#else
    typedef struct timespec Timer;

    struct timespec 
    start_timer()
    {
        struct timespec t0;
        clock_gettime(CLOCK_MONOTONIC, &t0);
        return t0;
    }
 
    double
    elapse_timer(t0)
        struct timespec t0;
    {
        struct timespec t1, diff;
        double tdiff;
        clock_gettime(CLOCK_MONOTONIC, &t1);
        diff.tv_nsec = t1.tv_nsec - t0.tv_nsec;
        diff.tv_sec = t1.tv_sec - t0.tv_sec;
        if (diff.tv_nsec < 0) {
            diff.tv_nsec += NANO;
            diff.tv_sec--;        
        }
        tdiff = diff.tv_sec + (double) diff.tv_nsec / NANO;
        return tdiff;
    }
#endif

int create_tcp(int port)
{
    int sock = 0;
    struct sockaddr_in address;
    
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(port);
    
    sock = socket(AF_INET, SOCK_STREAM, 0);
    bind(sock, (struct sockaddr *)&address, sizeof(address));
    listen(sock, 10);
    
    return sock;
}


void init()
{
#ifdef _WIN32
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);
#endif
}

int main(int argc, char *argv[])
{
    int serv_sock, cl_sock;
    struct sockaddr_in address;
    Timer t;
    char msg[200], ds[30];
    double d;
    int addrlen = sizeof(struct sockaddr_in);
    init();
    serv_sock = create_tcp(8080);

    t = start_timer();
    while (1) {
        cl_sock = accept(serv_sock, 
                         (struct sockaddr *)&address, &addrlen);
        d = elapse_timer(t);
        printf("%.3f\n", d);
        sprintf(ds, "%.3f", d);
        sprintf(msg,
                "HTTP/1.0 200 OK\r\n"
                "Server: TimeServer\r\n"
                "Content-Type: text/plain\r\n"
                "Content-Length: %d\r\n"
                "Connection: close\r\n\r\n"
                "%s\r\n",
                strlen(ds), ds
                );
        send(cl_sock, msg, strlen(msg), 0);
        //close(cl_sock);
    }
    return 0;
}