server.c

#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <errno.h>
#define BUF 1024
#define PORT 6543

int main (int argc, char **argv) {
  mode_t mode = S_IRWXU;
  int create_socket, new_socket;
  socklen_t addrlen;
  char buffer[BUF];
  //char buffer1[] = "Dateiname:";
  int size;
  int err = 0;
  struct sockaddr_in address, cliaddress;
  //struct fuer Verzeichnis einlesen (scandir)
  int num_entries, i;
  int strsize;
  struct dirent /**namelist,*/ **list;
  const char *ptr = NULL;
  char wd[BUF];
  //fuer GET
  //FILE *from, *to;

  //Eingabe der Argumente ServerIP & Port
  if( argc < 3){
             printf("Usage: %s Port Downloadverzeichnis\n", argv[0]);
             exit(EXIT_FAILURE);
      }
  //Verzeichnis anlegen
  //Zugriffsrechte erlauben
  umask(0);

  if((mkdir(argv[2], mode)) != -1 )
  {
      printf("Verzeichnis %s erstellt\n",argv[2]);

  }
  else
  {
      printf("Verzechnis %s schon vorhanden\n",argv[2]);

  }


  create_socket = socket (AF_INET, SOCK_STREAM, 0);

  memset(&address,0,sizeof(address));
  address.sin_family = AF_INET;
  address.sin_addr.s_addr = INADDR_ANY;strcpy(buffer,"OK");
  address.sin_port = htons (PORT);

  if (bind ( create_socket, (struct sockaddr *) &address, sizeof (address)) != 0) {
     perror("bind error");
     return EXIT_FAILURE;
  }
  listen (create_socket, 5);

  addrlen = sizeof (struct sockaddr_in);

  while (1) {
     printf("Waiting for connections...\n");
     new_socket = accept ( create_socket, (struct sockaddr *) &cliaddress, &addrlen );
     if (new_socket > 0)
     {
        printf ("Client connected from %s:%d...\n", inet_ntoa (cliaddress.sin_addr),ntohs(cliaddress.sin_port));
        strcpy(buffer,"Welcome to myserver, Please enter your command:\n");
        send(new_socket, buffer, strlen(buffer),0);
     }
     //Befehlsabarbeitungen bis Quit ausgefüird.
     do {
    //Befehl von Client erhalten
        size = recv (new_socket, buffer, BUF-1, 0);
        if( size > 0)
        {
             buffer[size] = '\0';

        if(strncmp(buffer, "LIST",4) == 0)
        {

                printf ("Message received: %s\n", buffer);
                ptr = argv[2];
                if((num_entries = scandir(ptr, &list, 0, alphasort)) < 0)
                {
                    fprintf (stderr, "Unerwarteter Fehler\n");
                    exit (EXIT_FAILURE);
                }

                chdir(ptr);
                getcwd (wd, BUF);
                printf("%d Dateien im Verzeichnis: %s\n", num_entries, wd);
                send(new_socket, &num_entries, sizeof(num_entries), 0);
                if(num_entries > 0 )
                {
                    for(i = num_entries; i; --i)
                    {
                        buffer[0] = '\0';
                        sprintf(buffer, "%s\n", list[i-1]->d_name);
                        printf(buffer);
                        strsize = strlen(buffer);
                        send(new_socket, &strsize, sizeof(strsize), 0);
                        send(new_socket, buffer, strlen(buffer),0);
                        free(list[i-1]);
                    }
                    free(list);
                }
                else { err++; }
                printf("\n");


            //ok falls kein Fehler besteht
            if(err==0)
            {
                strcpy(buffer,"OK");
                send(new_socket, buffer, strlen(buffer),0);
            }
            else
            {
                strcpy(buffer,"ERROR");
                send(new_socket, buffer, strlen(buffer),0);
            }
        }
        else if(strncmp(buffer, "GET",3) == 0)
        {
            printf ("Message received: %s\n", buffer);


        }


        }
        else if (size == 0)
        {
           printf("Client closed remote socket\n");
           break;
        }
        else
        {
           perror("recv error");
           return EXIT_FAILURE;
        }
     } while (strncmp (buffer, "QUIT", 4)  != 0);
     close (new_socket);
  }
  close (create_socket);
  return EXIT_SUCCESS;
}