Verify FTP SSL Server Certificate

This example demonstrates how to verify the FTP server's certificate and authenticity. The intent is to verify the authenticity of the server before passing a login/password to it.

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#include <C_CkFtp2.h>
#include <C_CkCert.h>

void ChilkatSample(void)
    {
    HCkFtp2 ftp;
    BOOL success;
    HCkCert cert;

    ftp = CkFtp2_Create();

    //  Any string unlocks the component for the 1st 30-days.
    success = CkFtp2_UnlockComponent(ftp,"Anything for 30-day trial");
    if (success != TRUE) {
        printf("%s\n",CkFtp2_lastErrorText(ftp));
        return;
    }

    CkFtp2_putHostname(ftp,"ftp.myftpserver.com");
    CkFtp2_putUsername(ftp,"myUsername");
    CkFtp2_putPassword(ftp,"myPassword");

    //  Establish an AUTH SSL secure channel after connection
    //  on the standard FTP port 21.
    CkFtp2_putAuthSsl(ftp,TRUE);

    //  The Ssl property is for establishing an implicit SSL connection
    //  on port 990.  Do not set it.
    CkFtp2_putSsl(ftp,FALSE);

    //  Indicate that the FTP server must have a verifiable SSL certificate.
    //  Do not accept self-signed certs or certificates that are
    //  expired, revoked, or cannot be verified to a root authority:
    CkFtp2_putRequireSslCertVerify(ftp,TRUE);

    //  You may also set a requirement.  In this example,
    //  the certificate's Common Name (CN) must match the
    //  required string exactly:
    CkFtp2_SetSslCertRequirement(ftp,"subjectcn","Chilkat Software, Inc.");

    //  Connect and login to the FTP server.
    success = CkFtp2_Connect(ftp);
    if (success != TRUE) {
        printf("%s\n",CkFtp2_lastErrorText(ftp));
        return;
    }
    else {
        //  LastErrorText contains information even when
        //  successful. This allows you to visually verify
        //  that the secure connection actually occurred.
        printf("%s\n",CkFtp2_lastErrorText(ftp));
    }

    //  After logging on, you may examine the FTP server's cert:

    cert = CkFtp2_GetSslServerCert(ftp);
    if (cert == 0 ) {
        printf("No server certificate!\n");
    }
    else {
        //  Display the distinguished name of the SSL cert.
        printf("%s\n",CkCert_subjectDN(cert));
    }

    printf("Secure FTP Channel Established!\n");

    //  Do whatever you're doing to do ...
    //  upload files, download files, etc...

    CkFtp2_Disconnect(ftp);

    CkFtp2_Dispose(ftp);

    }