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{{task|Programming environment operations}}[[Category:Networking and Web Interaction]] |
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Connect to a server, change directory, list its contents and download a file as binary using the FTP protocol. Use passive mode if available. |
Connect to a server, change directory, list its contents and download a file as binary using the FTP protocol. Use passive mode if available. |
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Revision as of 11:03, 22 August 2015
You are encouraged to solve this task according to the task description, using any language you may know.
Connect to a server, change directory, list its contents and download a file as binary using the FTP protocol. Use passive mode if available.
Batch File
This uses the native FTP.EXE in Windows. I am not sure, but I think FTP.EXE client does not support passive mode. <lang dos>::Playing with FTP
- Batch File Implementation
@echo off
set site="ftp.hq.nasa.gov" set user="anonymous" set pass="ftptest@example.com" set dir="pub/issoutreach/Living in Space Stories (MP3 Files)" set download="Gravity in the Brain.mp3"
( echo.open %site% echo.user %user% %pass% echo.dir echo.!echo. echo.!echo.This is a just a text to seperate two directory listings. echo.!echo. echo.cd %dir% echo.dir echo.binary echo.get %download% echo.disconnect )|ftp -n</lang>
- Output:
\Desktop>RCFTP -rw-r--r-- 1 ftpadmin ftp-adm 3997 May 26 1998 README drwxrwx-wx 6 lgipson armd 696320 Jan 23 2015 armd drwxrwx-wx 2 chmgt ftp-adm 4096 Aug 18 16:17 chmgt -r-xr-xr-x 1 root root 18120 Nov 28 2001 ftp-exec drwxrws-wx 2 ftpadmin ftp-adm 57344 Aug 18 13:08 incoming -rw-rw-r-- 1 ftpadmin ftp-adm 133 Jan 29 1996 index.html drwx------ 2 root root 4096 Apr 11 2003 lost+found drwxr-sr-x 2 ftpadmin ftp-adm 4096 Apr 14 1998 office drwxrwsr-x 17 ftpadmin ftp-adm 4096 Nov 4 2013 pub -rw-r--r-- 1 root ftp-adm 26 Jan 27 2011 robots.txt This is a just a text to seperate two directory listings. -rw-rw-r-- 1 109 space-station 2327118 May 9 2005 09sept_spacepropulsion.mp3 -rw-rw-r-- 1 109 space-station 1260304 May 9 2005 Can People go to Mars.mp3 -rw-rw-r-- 1 109 space-station 1350270 May 9 2005 Distill some water.mp3 -rw-rw-r-- 1 109 space-station 1290888 May 9 2005 Good Vibrations.mp3 -rw-rw-r-- 1 109 space-station 1431834 May 9 2005 Gravity Hurts_So good.mp3 -rw-rw-r-- 1 109 space-station 1072644 May 9 2005 Gravity in the Brain.mp3 -rw-rw-r-- 1 109 space-station 1230594 May 9 2005 Power to the ISS.mp3 -rw-rw-r-- 1 109 space-station 1309062 May 9 2005 Space Bones.mp3 -rw-rw-r-- 1 109 space-station 2292715 May 9 2005 Space Power.mp3 -rw-rw-r-- 1 109 space-station 772075 May 9 2005 We have a solution.mp3 -rw-rw-r-- 1 109 space-station 1134654 May 9 2005 When Space Makes you Dizzy.mp3 \Desktop>
C
Using ftplib <lang c>
- include <ftplib.h>
int main(void) {
netbuf *nbuf;
FtpInit();
FtpConnect("kernel.org", &nbuf);
FtpLogin("anonymous", "", nbuf);
FtpOptions(FTPLIB_CONNMODE, FTPLIB_PASSIVE, nbuf);
FtpChdir("pub/linux/kernel", nbuf);
FtpDir((void*)0, ".", nbuf);
FtpGet("ftp.README", "README", FTPLIB_ASCII, nbuf);
FtpQuit(nbuf);
return 0;
} </lang>
Go
Using the FTP package from github.com/stacktic/ftp. <lang go>package main
import ( "fmt" "io" "log" "os"
"github.com/stacktic/ftp" )
func main() { // Hard-coded demonstration values const ( hostport = "localhost:21" username = "anonymous" password = "anonymous" dir = "pub" file = "somefile.bin" )
conn, err := ftp.Connect(hostport) if err != nil { log.Fatal(err) } defer conn.Quit() fmt.Println(conn)
if err = conn.Login(username, password); err != nil { log.Fatal(err) } if err = conn.ChangeDir(dir); err != nil { log.Fatal(err) } fmt.Println(conn.CurrentDir()) files, err := conn.List(".") if err != nil { log.Fatal(err) } for _, f := range files { fmt.Printf("%v %12d %v %v\n", f.Time, f.Size, f.Type, f.Name) }
r, err := conn.Retr(file) if err != nil { log.Fatal(err) } defer r.Close()
f, err := os.Create(file) if err != nil { log.Fatal(err) } defer f.Close()
n, err := io.Copy(f, r) if err != nil { log.Fatal(err) }
fmt.Println("Wrote", n, "bytes to", file) }</lang>
J
<lang J> require 'web/gethttp'
gethttp 'ftp://anonymous:example@ftp.hq.nasa.gov/pub/issoutreach/Living%20in%20Space%20Stories%20(MP3%20Files)/'
-rw-rw-r-- 1 109 space-station 2327118 May 9 2005 09sept_spacepropulsion.mp3 -rw-rw-r-- 1 109 space-station 1260304 May 9 2005 Can People go to Mars.mp3 -rw-rw-r-- 1 109 space-station 1350270 May 9 2005 Distill some water.mp3 -rw-rw-r-- 1 109 space-station 1290888 May 9 2005 Good Vibrations.mp3 -rw-rw-r-- 1 109 space-station 1431834 May 9 2005 Gravity Hurts_So good.mp3 -rw-rw-r-- 1 109 space-station 1072644 May 9 2005 Gravity in the Brain.mp3 -rw-rw-r-- 1 109 space-station 1230594 May 9 2005 Power to the ISS.mp3 -rw-rw-r-- 1 109 space-station 1309062 May 9 2005 Space Bones.mp3 -rw-rw-r-- 1 109 space-station 2292715 May 9 2005 Space Power.mp3 -rw-rw-r-- 1 109 space-station 772075 May 9 2005 We have a solution.mp3 -rw-rw-r-- 1 109 space-station 1134654 May 9 2005 When Space Makes you Dizzy.mp3
#file=: gethttp rplc&(' ';'%20') 'ftp://anonymous:example@ftp.hq.nasa.gov/pub/issoutreach/Living in Space Stories (MP3 Files)/We have a solution.mp3'
772075</lang>
Java
requires apache.commons.net <lang java>import java.io.FileOutputStream; import java.io.IOException; import java.io.OutputStream; import org.apache.commons.net.ftp.FTP; import org.apache.commons.net.ftp.FTPClient; import org.apache.commons.net.ftp.FTPFile; import org.apache.commons.net.ftp.FTPReply;
public class FTPconn {
public static void main(String[] args) throws IOException {
String server = "ftp.hq.nasa.gov";
int port = 21;
String user = "anonymous";
String pass = "ftptest@example.com";
OutputStream output = null;
FTPClient ftpClient = new FTPClient();
try {
ftpClient.connect(server, port);
serverReply(ftpClient);
int replyCode = ftpClient.getReplyCode();
if (!FTPReply.isPositiveCompletion(replyCode)) {
System.out.println("Failure. Server reply code: " + replyCode);
return;
}
serverReply(ftpClient);
if (!ftpClient.login(user, pass)) {
System.out.println("Could not login to the server.");
return;
}
String dir = "pub/issoutreach/Living in Space Stories (MP3 Files)/";
if (!ftpClient.changeWorkingDirectory(dir)) {
System.out.println("Change directory failed.");
return;
}
ftpClient.enterLocalPassiveMode();
for (FTPFile file : ftpClient.listFiles())
System.out.println(file);
String filename = "Can People go to Mars.mp3";
output = new FileOutputStream(filename);
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
if (!ftpClient.retrieveFile(filename, output)) {
System.out.println("Retrieving file failed");
return;
}
serverReply(ftpClient);
ftpClient.logout();
} finally {
if (output != null)
output.close();
}
}
private static void serverReply(FTPClient ftpClient) {
for (String reply : ftpClient.getReplyStrings()) {
System.out.println(reply);
}
}
}</lang>
Output:
220-Warning: This system is owned and operated by the US Federal Government.
Unauthorized access to this system is a violation of US Federal
law and could lead to prosecution.
This is NASA HQ ANONYMOUS FTP SERVER.
Please read the README file located in the initial server root directory.
IF you place files into the /incoming directory, it is IMPERATIVE that you
notify ftp-admin@hq.nasa.gov that you have done so and of your intended
disposition of those files. Absent such notification, all files placed
in /incoming that cannot be identified will be immediately deleted.
220 FTP Server Ready
220-Warning: This system is owned and operated by the US Federal Government.
Unauthorized access to this system is a violation of US Federal
law and could lead to prosecution.
This is NASA HQ ANONYMOUS FTP SERVER.
Please read the README file located in the initial server root directory.
IF you place files into the /incoming directory, it is IMPERATIVE that you
notify ftp-admin@hq.nasa.gov that you have done so and of your intended
disposition of those files. Absent such notification, all files placed
in /incoming that cannot be identified will be immediately deleted.
220 FTP Server Ready
-rw-rw-r-- 1 109 space-station 2327118 May 9 2005 09sept_spacepropulsion.mp3
-rw-rw-r-- 1 109 space-station 1260304 May 9 2005 Can People go to Mars.mp3
-rw-rw-r-- 1 109 space-station 1350270 May 9 2005 Distill some water.mp3
-rw-rw-r-- 1 109 space-station 1290888 May 9 2005 Good Vibrations.mp3
-rw-rw-r-- 1 109 space-station 1431834 May 9 2005 Gravity Hurts_So good.mp3
-rw-rw-r-- 1 109 space-station 1072644 May 9 2005 Gravity in the Brain.mp3
-rw-rw-r-- 1 109 space-station 1230594 May 9 2005 Power to the ISS.mp3
-rw-rw-r-- 1 109 space-station 1309062 May 9 2005 Space Bones.mp3
-rw-rw-r-- 1 109 space-station 2292715 May 9 2005 Space Power.mp3
-rw-rw-r-- 1 109 space-station 772075 May 9 2005 We have a solution.mp3
-rw-rw-r-- 1 109 space-station 1134654 May 9 2005 When Space Makes you Dizzy.mp3
226 Transfer complete
Python
<lang Python> from ftplib import FTP ftp = FTP('kernel.org') ftp.login() ftp.cwd('/pub/linux/kernel') ftp.set_pasv(True) # Default since Python 2.1 print ftp.retrlines('LIST') print ftp.retrbinary('RETR README', open('README', 'wb').write) ftp.quit() </lang>
Racket
Note: net/ftp in Racket uses passive mode exclusively. <lang racket>
- lang racket
(require net/ftp) (let* ([server "kernel.org"]
[remote-dir "/pub/linux/kernel/"]
[conn (ftp-establish-connection
server
21
"anonymous"
"")])
(ftp-cd conn remote-dir)
(map
(lambda (elem) (displayln (string-join elem "\t")))
(ftp-directory-list conn "."))
(ftp-download-file conn "." "README")
(ftp-close-connection conn))
</lang>
REBOL
<lang REBOL> system/schemes/ftp/passive: on print read ftp://kernel.org/pub/linux/kernel/ write/binary %README read/binary ftp://kernel.org/pub/linux/kernel/README </lang>
Ruby
<lang ruby>require 'net/ftp'
Net::FTP.open('ftp.ed.ac.uk', "anonymous","aaa@gmail.com" ) do |ftp|
ftp.passive = true
ftp.chdir('pub/courses')
ftp.list.each{|e| puts e}
ftp.getbinaryfile("make.notes.tar")
end</lang> The connection is closed automatically at the end of the block.
Tcl
Using package ftp
<lang Tcl> package require ftp
set conn [::ftp::Open kernel.org anonymous "" -mode passive]
- ftp::Cd $conn /pub/linux/kernel
foreach line [ftp::NList $conn] {
puts $line
}
- ftp::Type $conn binary
- ftp::Get $conn README README
</lang>
Using a virtual file system
An alternative approach that uses the package TclVFS to access ftp:// paths as a virtual file system.
<lang tcl> package require vfs::urltype vfs::urltype::Mount ftp
- Patch to enable FTP passive mode.
source vfsftpfix.tcl
set dir [pwd] cd ftp://kernel.org/pub/linux/kernel foreach line [glob -dir ftp://kernel.org/pub/linux/kernel *] {
puts $line
} file copy README [file join $dir README] </lang>
The file vfsftpfix.tcl with the passive mode patch (see http://wiki.tcl.tk/12837): <lang tcl>
- Replace vfs::ftp::Mount to enable vfs::ftp to work in passive
- mode and make that the default.
package require vfs::ftp proc vfs::ftp::Mount {dirurl local {mode passive}} {
set dirurl [string trim $dirurl]
::vfs::log "ftp-vfs: attempt to mount $dirurl at $local"
if {[string index $dirurl end] != "/"} {
::vfs::log "ftp-vfs: adding missing directory delimiter to mount point"
append dirurl "/"
}
set urlRE {(?:ftp://)?(?:([^@:]*)(?::([^@]*))?@)?([^/:]+)(?::([0-9]*))?/(.*/)?$}
if {![regexp $urlRE $dirurl - user pass host port path]} {
return -code error "Sorry I didn't understand\
the url address \"$dirurl\""
}
if {![string length $user]} {
set user anonymous
}
if {![string length $port]} {
set port 21
}
set fd [::ftp::Open $host $user $pass -port $port -output ::vfs::ftp::log -mode $mode]
if {$fd == -1} {
error "Mount failed"
}
if {$path != ""} {
if {[catch {
::ftp::Cd $fd $path
} err]} {
ftp::Close $fd
error "Opened ftp connection, but then received error: $err"
}
}
if {![catch {vfs::filesystem info $dirurl}]} {
# unmount old mount
::vfs::log "ftp-vfs: unmounted old mount point at $dirurl"
vfs::unmount $dirurl
}
::vfs::log "ftp $host, $path mounted at $fd"
vfs::filesystem mount $local [list vfs::ftp::handler $fd $path]
# Register command to unmount
vfs::RegisterMount $local [list ::vfs::ftp::Unmount $fd]
return $fd
} </lang>
zkl
Using the cURL library, doing this from the REPL. Moving around in the tree isn't supported. <lang zkl>zkl: var cURL=Import("zklCurl") zkl: var d=cURL().get("ftp.hq.nasa.gov/pub/issoutreach/Living in Space Stories (MP3 Files)/") L(Data(2,567),1630,23) // downloaded listing, 1630 bytes of header, 23 bytes of trailer zkl: d[0][1630,-23].text -rw-rw-r-- 1 109 space-station 2327118 May 9 2005 09sept_spacepropulsion.mp3 ... -rw-rw-r-- 1 109 space-station 1134654 May 9 2005 When Space Makes you Dizzy.mp3
zkl: d=cURL().get("ftp.hq.nasa.gov/pub/issoutreach/Living in Space Stories (MP3 Files)/When Space Makes you Dizzy.mp3") L(Data(1,136,358),1681,23) zkl: File("foo.mp3","w").write(d[0][1681,-23]) 1134654 // note that this matches size in listing</lang> The resulting file foo.mp3 has a nice six minute description of what can happen when returning from space.