C++

HTTPS Server Certificate Require Hostname Match

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Demonstrates and explains the RequireHostnameMatch property. C++

#include <CkHttp.h>

void ChilkatSample(void)
    {
    //  The RequireHostnameMatch property was added in Chilkat v11.0.0
    //  to ensure the URL's hostname matches at least one of the server certificate SAN's (Subject Alternative Names)
    //  
    //  In actuality, it is the SNI hostname that must match.  If the SNI hostname is not explicitly set,
    //  then Chilkat uses the hostname from the URL as the SNI hostname.

    //  Here's an example using chilkatsoft.com
    //  The SSL server certificate for chilkatsoft.com has 2 Subject Alternative Names:
    //  
    //  1) DNS Name: *.chilkatsoft.com
    //  2) DNS Name: chilkatsoft.com
    //  
    //  See Explaining the SNI Hostname in TLS

    CkHttp http;

    http.put_RequireHostnameMatch(true);

    //  This should succeed because "www.chilkatsoft.com" matches the SAN entry "*.chilkatsoft.com"
    const char *html = http.quickGetStr("https://www.chilkatsoft.com/helloWorld.html");
    std::cout << "1) Succeeded: " << http.get_LastMethodSuccess() << "\r\n";

    //  At the time of writing this example, the IP address for chilkatsoft.com is 3.101.18.47
    //  If we send the request using the IP address, it will fail because the IP address is does 
    //  not match any of the SAN entries in the server certificate.
    html = http.quickGetStr("https://3.101.18.47/helloWorld.html");
    std::cout << "2) Succeeded: " << http.get_LastMethodSuccess() << "\r\n";

    //  However, it will succeed if we explicitly set the SNI hostname.
    http.put_SniHostname("www.chilkatsoft.com");
    html = http.quickGetStr("https://3.101.18.47/helloWorld.html");
    std::cout << "3) Succeeded: " << http.get_LastMethodSuccess() << "\r\n";

    //  Remove our explicit SNI hostname.
    http.put_SniHostname("");

    //  Now let's try wrong.host.badssl.com
    //  The SSL server certificate for badssl.com has 2 Subject Alternative Names:
    //  
    //  1) DNS Name: *.badssl.com
    //  2) DNS Name: badssl.com

    //  The domain wrong.host.badssl.com will fail the RequireHostnameMatch because
    //  the wildcarded domain SAN entry only extends 1 level deep.  
    html = http.quickGetStr("https://wrong.host.badssl.com/");
    std::cout << "4) Succeeded: " << http.get_LastMethodSuccess() << "\r\n";

    //  The expected output is:
    //  1) Succeeded: True
    //  2) Succeeded: False
    //  3) Succeeded: True
    //  4) Succeeded: False
    }