Visual Basic 6.0 Requires Chilkat v11.0.0+

HTTPS Server Certificate Require Hostname Match

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Demonstrates and explains the RequireHostnameMatch property. Visual Basic 6.0

'  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

Dim http As New ChilkatHttp

http.RequireHostnameMatch = 1

'  This should succeed because "www.chilkatsoft.com" matches the SAN entry "*.chilkatsoft.com"
Dim html As String
html = http.QuickGetStr("https://www.chilkatsoft.com/helloWorld.html")
Debug.Print "1) Succeeded: " & http.LastMethodSuccess

'  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")
Debug.Print "2) Succeeded: " & http.LastMethodSuccess

'  However, it will succeed if we explicitly set the SNI hostname.
http.SniHostname = "www.chilkatsoft.com"
html = http.QuickGetStr("https://3.101.18.47/helloWorld.html")
Debug.Print "3) Succeeded: " & http.LastMethodSuccess

'  Remove our explicit SNI hostname.
http.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/")
Debug.Print "4) Succeeded: " & http.LastMethodSuccess

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