(Swift 3,4,5...) 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 Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let listenSslSocket = CkoSocket()!

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

    let cert = CkoCert()!
    // The 1st argument is the file path, the 2nd arg is the 
    // PFX file's password:
    var success: Bool = cert.loadPfxFile("chilkat.pfx", password: "test")
    if success != true {
        print("\(cert.lastErrorText!)")
        return
    }

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

    // Use the certificate:
    success = listenSslSocket.initSslServer(cert)
    if success != true {
        print("\(listenSslSocket.lastErrorText!)")
        return
    }

    // Bind and listen on a port:
    var myPort: Int = 8123
    // Allow for a max of 5 queued connect requests.
    var backLog: Int = 5
    success = listenSslSocket.bindAndListen(myPort, backlog: backLog)
    if success != true {
        print("\(listenSslSocket.lastErrorText!)")
        return
    }

    // 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.
    listenSslSocket.maxReadIdleMs = 10000
    listenSslSocket.maxSendIdleMs = 10000

    // Accept a single client connection and establish the secure SSL/TLS channel:
    var clientSock: CkoSocket?
    var maxWaitMillisec: Int = 20000
    clientSock = listenSslSocket.acceptNextConnection(maxWaitMillisec)
    if listenSslSocket.lastMethodSuccess == false {
        print("\(listenSslSocket.lastErrorText!)")
        return
    }

    // The client (in this example) is going to send a "Hello Server! -EOM-" 
    // message.  Read it:
    var receivedMsg: String? = clientSock!.receive(untilMatch: "-EOM-")
    if clientSock!.lastMethodSuccess != true {
        print("\(clientSock!.lastErrorText!)")
        return
    }

    print("\(receivedMsg!)")

    // Send a "Hello Client! -EOM-" message:
    success = clientSock!.send("Hello Client! -EOM-")
    if success != true {
        print("\(clientSock!.lastErrorText!)")
        return
    }

    // Close the connection with the client
    // Wait a max of 20 seconds (20000 millsec)
    success = clientSock!.close(20000)

    clientSock = nil

}