CkPython

HTTPS Server Certificate Require Hostname Match

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Demonstrates and explains the RequireHostnameMatch property. CkPython

import chilkat

# 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

http = chilkat.CkHttp()

http.put_RequireHostnameMatch(True)

# This should succeed because "www.chilkatsoft.com" matches the SAN entry "*.chilkatsoft.com"
html = http.quickGetStr("https://www.chilkatsoft.com/helloWorld.html")
print("1) Succeeded: " + str(http.get_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")
print("2) Succeeded: " + str(http.get_LastMethodSuccess()))

# 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")
print("3) Succeeded: " + str(http.get_LastMethodSuccess()))

# 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/")
print("4) Succeeded: " + str(http.get_LastMethodSuccess()))

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