SSL: Several SSL-backend related fixes

axTLS:

This will make the axTLS backend perform the RFC2818 checks, honoring
the VERIFYHOST setting similar to the OpenSSL backend.

Generic for OpenSSL and axTLS:

Move the hostcheck and cert_hostcheck functions from the lib/ssluse.c
files to make them genericly available for both the OpenSSL, axTLS and
other SSL backends. They are now in the new lib/hostcheck.c file.

CyaSSL:

CyaSSL now also has the RFC2818 checks enabled by default. There is a
limitation that the verifyhost can not be enabled exclusively on the
Subject CN field comparison. This SSL backend will thus behave like the
NSS and the GnuTLS (meaning: RFC2818 ok, or bust). In other words:
setting verifyhost to 0 or 1 will disable the Subject Alt Names checks
too.

Schannel:

Updated the schannel information messages: Split the IP address usage
message from the verifyhost setting and changed the message about
disabling SNI (Server Name Indication, used in HTTP virtual hosting)
into a message stating that the Subject Alternative Names checks are
being disabled when verifyhost is set to 0 or 1. As a side effect of
switching off the RFC2818 related servername checks with
SCH_CRED_NO_SERVERNAME_CHECK
(http://msdn.microsoft.com/en-us/library/aa923430.aspx) the SNI feature
is being disabled. This effect is not documented in MSDN, but Wireshark
output clearly shows the effect (details on the libcurl maillist).

PolarSSL:

Fix the prototype change in PolarSSL of ssl_set_session() and the move
of the peer_cert from the ssl_context to the ssl_session. Found this
change in the PolarSSL SVN between r1316 and r1317 where the
POLARSSL_VERSION_NUMBER was at 0x01010100. But to accommodate the Ubuntu
PolarSSL version 1.1.4 the check is to discriminate between lower then
PolarSSL version 1.2.0 and 1.2.0 and higher. Note: The PolarSSL SVN
trunk jumped from version 1.1.1 to 1.2.0.

Generic:

All the SSL backends are fixed and checked to work with the
ssl.verifyhost as a boolean, which is an internal API change.

1 files changed, 91 insertions, 0 deletions

diff --git a/lib/hostcheck.c b/lib/hostcheck.c
new file mode 100644
index 000000000..c8c4ac30c
--- /dev/null
+++ b/lib/hostcheck.c
@@ -0,0 +1,91 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2012, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+#include "setup.h"
+
+#include "hostcheck.h"
+#include "rawstr.h"
+
+/*
+ * Match a hostname against a wildcard pattern.
+ * E.g.
+ *  "foo.host.com" matches "*.host.com".
+ *
+ * We use the matching rule described in RFC6125, section 6.4.3.
+ * http://tools.ietf.org/html/rfc6125#section-6.4.3
+ */
+
+int Curl_hostmatch(const char *hostname, const char *pattern)
+{
+  const char *pattern_label_end, *pattern_wildcard, *hostname_label_end;
+  int wildcard_enabled;
+  size_t prefixlen, suffixlen;
+  pattern_wildcard = strchr(pattern, '*');
+  if(pattern_wildcard == NULL)
+    return Curl_raw_equal(pattern, hostname) ?
+      CURL_HOST_MATCH : CURL_HOST_NOMATCH;
+
+  /* We require at least 2 dots in pattern to avoid too wide wildcard
+     match. */
+  wildcard_enabled = 1;
+  pattern_label_end = strchr(pattern, '.');
+  if(pattern_label_end == NULL || strchr(pattern_label_end+1, '.') == NULL ||
+     pattern_wildcard > pattern_label_end ||
+     Curl_raw_nequal(pattern, "xn--", 4)) {
+    wildcard_enabled = 0;
+  }
+  if(!wildcard_enabled)
+    return Curl_raw_equal(pattern, hostname) ?
+      CURL_HOST_MATCH : CURL_HOST_NOMATCH;
+
+  hostname_label_end = strchr(hostname, '.');
+  if(hostname_label_end == NULL ||
+     !Curl_raw_equal(pattern_label_end, hostname_label_end))
+    return CURL_HOST_NOMATCH;
+
+  /* The wildcard must match at least one character, so the left-most
+     label of the hostname is at least as large as the left-most label
+     of the pattern. */
+  if(hostname_label_end - hostname < pattern_label_end - pattern)
+    return CURL_HOST_NOMATCH;
+
+  prefixlen = pattern_wildcard - pattern;
+  suffixlen = pattern_label_end - (pattern_wildcard+1);
+  return Curl_raw_nequal(pattern, hostname, prefixlen) &&
+    Curl_raw_nequal(pattern_wildcard+1, hostname_label_end - suffixlen,
+                    suffixlen) ?
+    CURL_HOST_MATCH : CURL_HOST_NOMATCH;
+}
+
+int Curl_cert_hostcheck(const char *match_pattern, const char *hostname)
+{
+  if(!match_pattern || !*match_pattern ||
+      !hostname || !*hostname) /* sanity check */
+    return 0;
+
+  if(Curl_raw_equal(hostname, match_pattern)) /* trivial case */
+    return 1;
+
+  if(Curl_hostmatch(hostname,match_pattern) == CURL_HOST_MATCH)
+    return 1;
+  return 0;
+}