(Visual FoxPro) 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".

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loListenSslSocket
LOCAL loCert
LOCAL lnSuccess
LOCAL lnMyPort
LOCAL lnBackLog
LOCAL loClientSock
LOCAL lnMaxWaitMillisec
LOCAL lcReceivedMsg

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Socket')
loListenSslSocket = CreateObject('Chilkat.Socket')

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loCert = CreateObject('Chilkat.Cert')
* The 1st argument is the file path, the 2nd arg is the 
* PFX file's password:
lnSuccess = loCert.LoadPfxFile("chilkat.pfx","test")
IF (lnSuccess <> 1) THEN
    ? loCert.LastErrorText
    RELEASE loListenSslSocket
    RELEASE loCert
    CANCEL
ENDIF

* 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.
loListenSslSocket.AddSslAcceptableClientCaDn("C=SE, O=AddTrust AB, OU=AddTrust External TTP Network, CN=AddTrust External CA Root")
loListenSslSocket.AddSslAcceptableClientCaDn("O=Digital Signature Trust Co., CN=DST Root CA X3")

* Use the certificate:
lnSuccess = loListenSslSocket.InitSslServer(loCert)
IF (lnSuccess <> 1) THEN
    ? loListenSslSocket.LastErrorText
    RELEASE loListenSslSocket
    RELEASE loCert
    CANCEL
ENDIF

* Bind and listen on a port:
lnMyPort = 8123
* Allow for a max of 5 queued connect requests.
lnBackLog = 5
lnSuccess = loListenSslSocket.BindAndListen(lnMyPort,lnBackLog)
IF (lnSuccess <> 1) THEN
    ? loListenSslSocket.LastErrorText
    RELEASE loListenSslSocket
    RELEASE loCert
    CANCEL
ENDIF

* 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 
* AcceptNextConnection can hang indefinitely during the SSL handshake process. 
* Make sure these properties are set to appropriate values before calling AcceptNextConnection.

* Set a 10 second max for waiting to read/write.  This is for the SSL/TLS handshake establishment.
loListenSslSocket.MaxReadIdleMs = 10000
loListenSslSocket.MaxSendIdleMs = 10000

* Accept a single client connection and establish the secure SSL/TLS channel:

lnMaxWaitMillisec = 20000
loClientSock = loListenSslSocket.AcceptNextConnection(lnMaxWaitMillisec)
IF (loListenSslSocket.LastMethodSuccess = 0) THEN
    ? loListenSslSocket.LastErrorText
    RELEASE loListenSslSocket
    RELEASE loCert
    CANCEL
ENDIF

* The client (in this example) is going to send a "Hello Server! -EOM-" 
* message.  Read it:
lcReceivedMsg = loClientSock.ReceiveUntilMatch("-EOM-")
IF (loClientSock.LastMethodSuccess <> 1) THEN
    ? loClientSock.LastErrorText
    RELEASE loListenSslSocket
    RELEASE loCert
    CANCEL
ENDIF

? lcReceivedMsg

* Send a "Hello Client! -EOM-" message:
lnSuccess = loClientSock.SendString("Hello Client! -EOM-")
IF (lnSuccess <> 1) THEN
    ? loClientSock.LastErrorText
    RELEASE loListenSslSocket
    RELEASE loCert
    CANCEL
ENDIF

* Close the connection with the client
* Wait a max of 20 seconds (20000 millsec)
lnSuccess = loClientSock.Close(20000)

RELEASE loClientSock

RELEASE loListenSslSocket
RELEASE loCert