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winssl: Enable hostname verification of IP address using SAN or CN

Original commit message was:
 Don't omit CN verification in SChannel when an IP address is used.

Side-effect of this change:
 SChannel and CryptoAPI do not support the iPAddress subjectAltName
 according to RFC 2818. If present, SChannel will first compare the
 IP address to the dNSName subjectAltNames and then fallback to the
 most specific Common Name in the Subject field of the certificate.

 This means that after this change curl will not connect to SSL/TLS
 hosts as long as the IP address is not specified in the SAN or CN
 of the server certificate or the verifyhost option is disabled.
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1 parent c27cc68 commit 63fc8ee7be2b712e7af5029f4f8a86a0dfd71b38 @d235j d235j committed with mback2k Feb 23, 2014
Showing with 9 additions and 11 deletions.
  1. +9 −11 lib/vtls/curl_schannel.c
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@@ -156,17 +156,6 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
infof(data, "schannel: disable server certificate revocation checks\n");
}
- if(Curl_inet_pton(AF_INET, conn->host.name, &addr)
-#ifdef ENABLE_IPV6
- || Curl_inet_pton(AF_INET6, conn->host.name, &addr6)
-#endif
- ) {
- schannel_cred.dwFlags |= SCH_CRED_NO_SERVERNAME_CHECK;
- infof(data, "schannel: using IP address, SNI is being disabled by "
- "disabling the servername check against the "
- "subject names in server certificates.\n");
- }
-
if(!data->set.ssl.verifyhost) {
schannel_cred.dwFlags |= SCH_CRED_NO_SERVERNAME_CHECK;
infof(data, "schannel: verifyhost setting prevents Schannel from "
@@ -228,6 +217,15 @@ schannel_connect_step1(struct connectdata *conn, int sockindex)
}
}
+ /* Warn if SNI is disabled due to use of an IP address */
+ if(Curl_inet_pton(AF_INET, conn->host.name, &addr)
+#ifdef ENABLE_IPV6
+ || Curl_inet_pton(AF_INET6, conn->host.name, &addr6)
+#endif
+ ) {
+ infof(data, "schannel: using IP address, SNI is not supported by OS.\n");
+ }
+
/* setup output buffer */
InitSecBuffer(&outbuf, SECBUFFER_EMPTY, NULL, 0);
InitSecBufferDesc(&outbuf_desc, &outbuf, 1);

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