kc3-lang/libevent/sample/openssl_hostname_validation.h
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Hash : 64d9f161
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Date : 2013-02-27T17:16:27
use iSECPartners code to validate hostname in certificate The problem is that if you go to a website whose certificate does not match its hostname, it should fail. Try this in a web browser for https://www.kegel.com/ for example. Your web browser will say the certificate is for *.pair.com, not for www.kegel.com, and won't let you visit it without clicking through a bunch of scary warnings. However, prior to this commit, https-client was happy to fetch https://www.kegel.com/ without complaining. That is bad. Now, with this commit, it will properly complain, which is good: pelletier@chives:~/src/libevent/sample$ ./https-client https://www.kegel.com/ Got 'MatchNotFound' for hostname 'www.kegel.com' and certificate: /C=US/postalCode=15203/ST=Pennsylvania/L=Pittsburgh/street=Suite 210/street=2403 Sidney Street/O=pair Networks, Inc./OU=Provided by pair Networks, Inc./OU=PairWildcardSSL $250,000/CN=*.pair.com some request failed - no idea which one though! error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed ppelletier@chives:~/src/libevent/sample$ It will still succeed for sites with an exactly-matching certificate, such as https://github.com/ and that is also good! However, the problem is that the iSECPartners code doesn't handle wildcards, which means we reject https://ip.appspot.com/ even though it is perfectly legitimate, because we don't understand the wildcard: ppelletier@chives:~/src/libevent/sample$ ./https-client https://ip.appspot.com/ Got 'MatchNotFound' for hostname 'ip.appspot.com' and certificate: /C=US/ST=California/L=Mountain View/O=Google Inc/CN=*.appspot.com some request failed - no idea which one though! error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed ppelletier@chives:~/src/libevent/sample$ So, we need to fix this. In other words, "to be continued..."
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sample/openssl_hostname_validation.h
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/* Obtained from: https://github.com/iSECPartners/ssl-conservatory */ /* Copyright (C) 2012, iSEC Partners. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ /* * Helper functions to perform basic hostname validation using OpenSSL. * * Please read "everything-you-wanted-to-know-about-openssl.pdf" before * attempting to use this code. This whitepaper describes how the code works, * how it should be used, and what its limitations are. * * Author: Alban Diquet * License: See LICENSE * */ typedef enum { MatchFound, MatchNotFound, NoSANPresent, MalformedCertificate, Error } HostnameValidationResult; /** * Validates the server's identity by looking for the expected hostname in the * server's certificate. As described in RFC 6125, it first tries to find a match * in the Subject Alternative Name extension. If the extension is not present in * the certificate, it checks the Common Name instead. * * Returns MatchFound if a match was found. * Returns MatchNotFound if no matches were found. * Returns MalformedCertificate if any of the hostnames had a NUL character embedded in it. * Returns Error if there was an error. */ HostnameValidationResult validate_hostname(const char *hostname, const X509 *server_cert);