Perl

Upgrade a Plain TCP Connection to TLS

Demonstrates Socket.ConvertToSsl, which upgrades an already-connected plain TCP socket to TLS by performing a client-side TLS handshake over the existing connection.

Background. This supports STARTTLS-style upgrades, where a protocol begins in plaintext and switches to TLS at a defined point. Perform the protocol-specific negotiation first, then call ConvertToSsl.

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Chilkat2 Perl

use strict;
use warnings;
use Chilkat2;

my $socket = Chilkat2::Socket->new;

# Connect as plain TCP (no TLS yet).
my $bTls = 0;
my $maxWaitMs = 5000;
my $success = $socket->Connect('example.com', 5000, $bTls, $maxWaitMs);
if (!$success) {
    print $socket->LastErrorText, "\n";
    exit;
}

# At the point where the application protocol permits a STARTTLS-style upgrade, perform any required
# negotiation, then upgrade the existing connection to TLS with a client-side handshake.
$success = $socket->ConvertToSsl();
if (!$success) {
    print $socket->LastErrorText, "\n";
    exit;
}

print "Connection upgraded to TLS.\n";