(Objective-C) Examine Client Certificates for an Accepted TLS Connection

Demonstrates how to access the client certificates for a TLS connection accepted by your application acting as the server.

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#import <CkoSocket.h>
#import <CkoCert.h>

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

CkoSocket *listenSslSocket = [[CkoSocket alloc] init];

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

CkoCert *cert = [[CkoCert alloc] init];
BOOL success = [cert LoadPfxFile: @"qa_data/serverCert/myServerCert.pfx" password: @"pfx_password"];
if (success != YES) {
    NSLog(@"%@",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"];

// Initialize with our server's TLS certificate.
success = [listenSslSocket InitSslServer: cert];
if (success != YES) {
    NSLog(@"%@",listenSslSocket.LastErrorText);
    return;
}

// Bind and listen on a port:
int myPort = 8123;
// Allow for a max of 5 queued connect requests.
int backLog = 5;
success = [listenSslSocket BindAndListen: [NSNumber numberWithInt: myPort] backlog: [NSNumber numberWithInt: backLog]];
if (success != YES) {
    NSLog(@"%@",listenSslSocket.LastErrorText);
    return;
}

// Accept the next incoming connection.
int maxWaitMillisec = 20000;
CkoSocket *clientSock = [listenSslSocket AcceptNextConnection: [NSNumber numberWithInt: maxWaitMillisec]];
if (listenSslSocket.LastMethodSuccess == NO) {
    NSLog(@"%@",listenSslSocket.LastErrorText);
    return;
}

// Examine the client certs chain.  The 1st cert will be the client certificate, and
// the subsequent certs will be the certs in the chain of authentication.
int numClientCerts = [clientSock.NumReceivedClientCerts intValue];
NSLog(@"%@%d",@"numClientCerts = ",numClientCerts);

int i = 0;
while (i < numClientCerts) {
    CkoCert *clientCert = [clientSock GetReceivedClientCert: [NSNumber numberWithInt: i]];
    NSLog(@"%@",clientCert.SubjectDN);

    i = i + 1;
}

// Close the connection with the client
success = [clientSock Close: [NSNumber numberWithInt: 1000]];