FTP Server and Client Implementation in C/C++

<syntaxhighlight lang="C" name="ftpserver">

/*FTP server*/

1. include <sys/socket.h>
2. include <netinet/in.h>
3. include <string.h>
4. include <stdio.h>
5. include <stdlib.h>

/*for getting file size using stat()*/

1. include<sys/stat.h>

/*for sendfile()*/

1. include<sys/sendfile.h>

/*for O_RDONLY*/

1. include<fcntl.h>

int main(int argc,char *argv[]) {

 struct sockaddr_in server, client;
 struct stat obj;
 int sock1, sock2;
 char buf[100], command[5], filename[20];
 int k, i, size, len, c;
 int filehandle;
 sock1 = socket(AF_INET, SOCK_STREAM, 0);
 if(sock1 == -1)
   {
     printf("Socket creation failed");
     exit(1);
   }
 server.sin_port = atoi(argv[1]);
 server.sin_addr.s_addr = 0;
 k = bind(sock1,(struct sockaddr*)&server,sizeof(server));
 if(k == -1)
   {
     printf("Binding error");
     exit(1);
   }
 k = listen(sock1,1);
 if(k == -1)
   {
     printf("Listen failed");
     exit(1);
   }
 len = sizeof(client);
 sock2 = accept(sock1,(struct sockaddr*)&client, &len);
 i = 1;
 while(1)
   {
     recv(sock2, buf, 100, 0);
     sscanf(buf, "%s", command);
     if(!strcmp(command, "ls"))

{ system("ls >temps.txt"); i = 0; stat("temps.txt",&obj); size = obj.st_size; send(sock2, &size, sizeof(int),0); filehandle = open("temps.txt", O_RDONLY); sendfile(sock2,filehandle,NULL,size); }

     else if(!strcmp(command,"get"))

{ sscanf(buf, "%s%s", filename, filename); stat(filename, &obj); filehandle = open(filename, O_RDONLY); size = obj.st_size; if(filehandle == -1) size = 0; send(sock2, &size, sizeof(int), 0); if(size) sendfile(sock2, filehandle, NULL, size);

}

     else if(!strcmp(command, "put"))
       {

int c = 0, len; char *f; sscanf(buf+strlen(command), "%s", filename); recv(sock2, &size, sizeof(int), 0); i = 1; while(1) { filehandle = open(filename, O_CREAT | O_EXCL | O_WRONLY, 0666); if(filehandle == -1) { sprintf(filename + strlen(filename), "%d", i); } else break; } f = malloc(size); recv(sock2, f, size, 0); c = write(filehandle, f, size); close(filehandle); send(sock2, &c, sizeof(int), 0);

       }
     else if(!strcmp(command, "pwd"))

{ system("pwd>temp.txt"); i = 0;

         FILE*f = fopen("temp.txt","r");
         while(!feof(f))
           buf[i++] = fgetc(f);
         buf[i-1] = '\0';

fclose(f);

         send(sock2, buf, 100, 0);

}

     else if(!strcmp(command, "cd"))
       {
         if(chdir(buf+3) == 0)

c = 1; else c = 0;

         send(sock2, &c, sizeof(int), 0);
       }

     else if(!strcmp(command, "bye") || !strcmp(command, "quit"))

{ printf("FTP server quitting..\n"); i = 1; send(sock2, &i, sizeof(int), 0); exit(0); }

   }
 return 0;

} </syntaxhighlight>

<syntaxhighlight lang="C" name="ftpclient"> /*FTP Client*/

1. include <sys/socket.h>
2. include <netinet/in.h>
3. include <string.h>
4. include <stdio.h>
5. include <stdlib.h>

/*for getting file size using stat()*/

1. include<sys/stat.h>

/*for sendfile()*/

1. include<sys/sendfile.h>

/*for O_RDONLY*/

1. include<fcntl.h>

int main(int argc,char *argv[]) {

 struct sockaddr_in server;
 struct stat obj;
 int sock;
 int choice;
 char buf[100], command[5], filename[20], *f;
 int k, size, status;
 int filehandle;
 sock = socket(AF_INET, SOCK_STREAM, 0);
 if(sock == -1)
   {
     printf("socket creation failed");
     exit(1);
   }
 server.sin_family = AF_INET;
 server.sin_port = atoi(argv[1]);
 server.sin_addr.s_addr = 0;
 k = connect(sock,(struct sockaddr*)&server, sizeof(server));
 if(k == -1)
   {
     printf("Connect Error");
     exit(1);
   }
 int i = 1;
 while(1)
   {
     printf("Enter a choice:\n1- get\n2- put\n3- pwd\n4- ls\n5- cd\n6- quit\n");
     scanf("%d", &choice);
     switch(choice)

{ case 1: printf("Enter filename to get: "); scanf("%s", filename); strcpy(buf, "get "); strcat(buf, filename); send(sock, buf, 100, 0); recv(sock, &size, sizeof(int), 0); if(!size) { printf("No such file on the remote directory\n\n"); break; } f = malloc(size); recv(sock, f, size, 0); while(1) { filehandle = open(filename, O_CREAT | O_EXCL | O_WRONLY, 0666); if(filehandle == -1) { sprintf(filename + strlen(filename), "%d", i);//needed only if same directory is used for both server and client } else break; } write(filehandle, f, size, 0); close(filehandle); strcpy(buf, "cat "); strcat(buf, filename); system(buf); break; case 2: printf("Enter filename to put to server: ");

         scanf("%s", filename);

filehandle = open(filename, O_RDONLY);

         if(filehandle == -1)
           {
             printf("No such file on the local directory\n\n");
             break;
           }
         strcpy(buf, "put ");

strcat(buf, filename); send(sock, buf, 100, 0); stat(filename, &obj); size = obj.st_size; send(sock, &size, sizeof(int), 0); sendfile(sock, filehandle, NULL, size); recv(sock, &status, sizeof(int), 0); if(status) printf("File stored successfully\n"); else printf("File failed to be stored to remote machine\n"); break; case 3: strcpy(buf, "pwd"); send(sock, buf, 100, 0); recv(sock, buf, 100, 0); printf("The path of the remote directory is: %s\n", buf); break; case 4: strcpy(buf, "ls");

         send(sock, buf, 100, 0);

recv(sock, &size, sizeof(int), 0);

         f = malloc(size);
         recv(sock, f, size, 0);

filehandle = creat("temp.txt", O_WRONLY); write(filehandle, f, size, 0); close(filehandle);

         printf("The remote directory listing is as follows:\n");

system("cat temp.txt"); break; case 5: strcpy(buf, "cd "); printf("Enter the path to change the remote directory: "); scanf("%s", buf + 3);

         send(sock, buf, 100, 0);

recv(sock, &status, sizeof(int), 0);

         if(status)
           printf("Remote directory successfully changed\n");
         else
           printf("Remote directory failed to change\n");
         break;

case 6: strcpy(buf, "quit");

         send(sock, buf, 100, 0);
         recv(sock, &status, 100, 0);

if(status) { printf("Server closed\nQuitting..\n"); exit(0); } printf("Server failed to close connection\n"); }

   }

}

</syntaxhighlight>

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