Objective-C

Upgrade an FTP Control Channel to TLS (ConvertToTls)

Demonstrates the Chilkat Ftp2.ConvertToTls method, which upgrades an already-connected clear FTP control channel to explicit TLS. It takes no arguments and is used with a manually staged connection created by ConnectOnly while Ssl is disabled.

Background: This exposes the explicit-FTPS AUTH TLS upgrade as a discrete step for the rare case where you need to do something on the clear connection first — inspect the greeting, apply a workaround — before securing it. In the normal case you simply set AuthTls and let Connect perform the upgrade automatically; this manual path exists for staged control.

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Objective-C

#import <CkoFtp2.h>

BOOL success = NO;

//  Demonstrates the Ftp2.ConvertToTls method, which upgrades an already-connected clear FTP control
//  channel to explicit TLS.  It takes no arguments.  It is used with a manually staged connection
//  created by ConnectOnly while Ssl is disabled.

CkoFtp2 *ftp = [[CkoFtp2 alloc] init];

ftp.Hostname = @"ftp.example.com";
ftp.Port = [NSNumber numberWithInt:21];

//  Connect in clear text first (Ssl is false).
success = [ftp ConnectOnly];
if (success == NO) {
    NSLog(@"%@",ftp.LastErrorText);
    return;
}

//  Upgrade the control channel to explicit TLS (AUTH TLS).
success = [ftp ConvertToTls];
if (success == NO) {
    NSLog(@"%@",ftp.LastErrorText);
    return;
}

//  Now authenticate over the encrypted control channel.
ftp.Username = @"myFtpLogin";
ftp.Password = @"myPassword";
success = [ftp LoginAfterConnectOnly];
if (success == NO) {
    NSLog(@"%@",ftp.LastErrorText);
    return;
}

NSLog(@"%@",@"Control channel upgraded to TLS and logged in.");

success = [ftp Disconnect];
if (success == NO) {
    NSLog(@"%@",ftp.LastErrorText);
    return;
}