(Tcl) Accept TLS Connection with Client Authentication

Demonstrates how to accept a TLS connection requiring client authentication. This is the case where the TLS client sends a certificate. It is also known as "Two-Way SSL".

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

set success 0

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

set listenSslSocket [new_CkSocket]

# An SSL/TLS server needs a digital certificate.  This example loads it from a PFX file.
# Note: This is the server's certificate.

set cert [new_CkCert]

# The 1st argument is the file path, the 2nd arg is the 
# PFX file's password:
set success [CkCert_LoadPfxFile $cert "chilkat.pfx" "test"]
if {$success == 0} then {
    puts [CkCert_lastErrorText $cert]
    delete_CkSocket $listenSslSocket
    delete_CkCert $cert
    exit
}

# To accept client client certificates in the TLS handshake,
# we must indicate a list of acceptable client certificate root CA DN's
# that are allowed.  (DN is an acronym for Distinguished Name.)
# Call AddSslAcceptableClientCaDn once for each acceptable CA DN.
# Here are a few examples so you can see the general format of a DN.
CkSocket_AddSslAcceptableClientCaDn $listenSslSocket "C=SE, O=AddTrust AB, OU=AddTrust External TTP Network, CN=AddTrust External CA Root"
CkSocket_AddSslAcceptableClientCaDn $listenSslSocket "O=Digital Signature Trust Co., CN=DST Root CA X3"

# Use the certificate:
set success [CkSocket_InitSslServer $listenSslSocket $cert]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $listenSslSocket]
    delete_CkSocket $listenSslSocket
    delete_CkCert $cert
    exit
}

# Bind and listen on a port:
set myPort 8123
# Allow for a max of 5 queued connect requests.
set backLog 5
set success [CkSocket_BindAndListen $listenSslSocket $myPort $backLog]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $listenSslSocket]
    delete_CkSocket $listenSslSocket
    delete_CkCert $cert
    exit
}

# If accepting an SSL/TLS connection, the SSL handshake is part of the connection
# establishment process. This involves a few back-and-forth messages between the 
# client and server to establish algorithms and a shared key to create the secure 
# channel. The sending and receiving of these messages are governed by the 
# MaxReadIdleMs and MaxSendIdleMs properties. If these properties are set to 0 
# (and this is the default unless changed by your application), then the 
# AcceptNext can hang indefinitely during the SSL handshake process. 
# Make sure these properties are set to appropriate values before calling AcceptNext.

# Set a 10 second max for waiting to read/write.  This is for the SSL/TLS handshake establishment.
CkSocket_put_MaxReadIdleMs $listenSslSocket 10000
CkSocket_put_MaxSendIdleMs $listenSslSocket 10000

# Accept a single client connection and establish the secure SSL/TLS channel:
set maxWaitMillisec 20000
set clientSock [new_CkSocket]

set success [CkSocket_AcceptNext $listenSslSocket $maxWaitMillisec $clientSock]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $listenSslSocket]
    delete_CkSocket $listenSslSocket
    delete_CkCert $cert
    delete_CkSocket $clientSock
    exit
}

# The client (in this example) is going to send a "Hello Server! -EOM-" 
# message.  Read it:
set receivedMsg [CkSocket_receiveUntilMatch $clientSock "-EOM-"]
if {[CkSocket_get_LastMethodSuccess $clientSock] == 0} then {
    puts [CkSocket_lastErrorText $clientSock]
    delete_CkSocket $listenSslSocket
    delete_CkCert $cert
    delete_CkSocket $clientSock
    exit
}

puts "$receivedMsg"

# Send a "Hello Client! -EOM-" message:
set success [CkSocket_SendString $clientSock "Hello Client! -EOM-"]
if {$success == 0} then {
    puts [CkSocket_lastErrorText $clientSock]
    delete_CkSocket $listenSslSocket
    delete_CkCert $cert
    delete_CkSocket $clientSock
    exit
}

# Close the connection with the client
# Wait a max of 20 seconds (20000 millsec)
set success [CkSocket_Close $clientSock 20000]

delete_CkSocket $listenSslSocket
delete_CkCert $cert
delete_CkSocket $clientSock