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

struct sockaddr_in endpoint;
FILE *flog;
char myhostname[1024];

int main(int argc, char **argv) {
    long lnIn1, lnIn2, lhIn1, lhIn2, lhOut, lnOut;
    int sdServerSocket, sdConnection, retval;
    socklen_t sin_size;
    struct sockaddr_in incoming;
    struct hostent *heLocalHost;
    char sign;

    sin_size = sizeof(struct sockaddr_in);

    sdServerSocket = socket(PF_INET, SOCK_STREAM, 0);
    gethostname(myhostname, 1023);
    heLocalHost = gethostbyname(myhostname);

    endpoint.sin_family = AF_INET;
    endpoint.sin_port = htons(14444);
    endpoint.sin_addr = *(struct in_addr*) 
                        heLocalHost->h_addr;
    memset(&(endpoint.sin_zero),0,8);

    printf("slucham na(listening on) %s:%d\n",
           inet_ntoa(endpoint.sin_addr),
           ntohs(endpoint.sin_port));

    retval = bind(sdServerSocket,
                  (struct sockaddr*) &endpoint,
                  sizeof(struct sockaddr));

    if (retval < 0) {
        printf("bind nie powiodl sie (bind failed)\n");
        return 1;
    }

    listen(sdServerSocket, 10);

    sin_size = sizeof(struct sockaddr_in);
    while ((sdConnection =

            accept(sdServerSocket,
                   (struct sockaddr*) &incoming,
                   &sin_size))

            > 0) {
        printf("Polaczenie z (connection with)%s:%d\n",
               inet_ntoa(incoming.sin_addr),
               ntohs(incoming.sin_port));

        if (recv(sdConnection, &lnIn1, sizeof(long),0) 
            != sizeof(long)) {
            printf("pierwszy recv nie powiodl sie (first recv failed)\n");
            close(sdConnection);
            continue;
        }
        lhIn1 = ntohl(lnIn1);

        lhOut = random();
        lnOut = htonl(lhOut);

        if (send(sdConnection, &lnOut, sizeof(long), 0) 
            != sizeof(long)) {
            printf("send nie powiodl sie (send failed)\n");
            close(sdConnection);
            continue;
        }

        if (recv(sdConnection, &lnIn2, sizeof(long), 0) 
            != sizeof(long)) {
            printf("drugi recv nie powiodl sie (second recv failed)\n");
            close(sdConnection);
            continue;
        }

        lhIn2 = ntohl(lnIn2);

        flog = fopen("zad.txt","a");
        if (lhIn2 == lhOut + 1) sign = '+'; 
        else sign = '-';
        fprintf(flog,"%c %ld from %s:%d : %ld, %ld\n",
                sign,
                lhIn1,
                inet_ntoa(incoming.sin_addr),
                ntohs(incoming.sin_port),
                lhOut,
                lhIn2);

        close(sdConnection);
        fflush(flog);
        fclose(flog);
    }

    printf("Blad sieci (network error)\n");
    fclose(flog);
    return 0;
}