pull in wildcard matching code from cURL

Now, https-client accepts both:

https://ip.appspot.com/ (matching wildcard certificate)
https://github.com/     (matching non-wildcard certificate)

but still rejects

https://www.kegel.com/  (non-matching wildcard certificate)

which should match the behavior of these sites in a web browser.

sample/hostcheck.c

@@ -0,0 +1,217 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2012, Daniel Stenberg, <[email protected]>, 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.
+ *
+ ***************************************************************************/
+
+/* This file is an amalgamation of hostcheck.c and most of rawstr.c
+   from cURL.  The contents of the COPYING file mentioned above are:
+
+COPYRIGHT AND PERMISSION NOTICE
+
+Copyright (c) 1996 - 2013, Daniel Stenberg, <[email protected]>.
+
+All rights reserved.
+
+Permission to use, copy, modify, and distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright
+notice and this permission notice appear in all copies.
+
+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 OF THIRD PARTY RIGHTS. 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.
+
+Except as contained in this notice, the name of a copyright holder shall not
+be used in advertising or otherwise to promote the sale, use or other dealings
+in this Software without prior written authorization of the copyright holder.
+*/
+
+#include "hostcheck.h"
+#include <string.h>
+
+/* Portable, consistent toupper (remember EBCDIC). Do not use toupper() because
+   its behavior is altered by the current locale. */
+static char Curl_raw_toupper(char in)
+{
+  switch (in) {
+  case 'a':
+    return 'A';
+  case 'b':
+    return 'B';
+  case 'c':
+    return 'C';
+  case 'd':
+    return 'D';
+  case 'e':
+    return 'E';
+  case 'f':
+    return 'F';
+  case 'g':
+    return 'G';
+  case 'h':
+    return 'H';
+  case 'i':
+    return 'I';
+  case 'j':
+    return 'J';
+  case 'k':
+    return 'K';
+  case 'l':
+    return 'L';
+  case 'm':
+    return 'M';
+  case 'n':
+    return 'N';
+  case 'o':
+    return 'O';
+  case 'p':
+    return 'P';
+  case 'q':
+    return 'Q';
+  case 'r':
+    return 'R';
+  case 's':
+    return 'S';
+  case 't':
+    return 'T';
+  case 'u':
+    return 'U';
+  case 'v':
+    return 'V';
+  case 'w':
+    return 'W';
+  case 'x':
+    return 'X';
+  case 'y':
+    return 'Y';
+  case 'z':
+    return 'Z';
+  }
+  return in;
+}
+
+/*
+ * Curl_raw_equal() is for doing "raw" case insensitive strings. This is meant
+ * to be locale independent and only compare strings we know are safe for
+ * this.  See http://daniel.haxx.se/blog/2008/10/15/strcasecmp-in-turkish/ for
+ * some further explanation to why this function is necessary.
+ *
+ * The function is capable of comparing a-z case insensitively even for
+ * non-ascii.
+ */
+
+static int Curl_raw_equal(const char *first, const char *second)
+{
+  while(*first && *second) {
+    if(Curl_raw_toupper(*first) != Curl_raw_toupper(*second))
+      /* get out of the loop as soon as they don't match */
+      break;
+    first++;
+    second++;
+  }
+  /* we do the comparison here (possibly again), just to make sure that if the
+     loop above is skipped because one of the strings reached zero, we must not
+     return this as a successful match */
+  return (Curl_raw_toupper(*first) == Curl_raw_toupper(*second));
+}
+
+static int Curl_raw_nequal(const char *first, const char *second, size_t max)
+{
+  while(*first && *second && max) {
+    if(Curl_raw_toupper(*first) != Curl_raw_toupper(*second)) {
+      break;
+    }
+    max--;
+    first++;
+    second++;
+  }
+  if(0 == max)
+    return 1; /* they are equal this far */
+
+  return Curl_raw_toupper(*first) == Curl_raw_toupper(*second);
+}
+
+/*
+ * 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
+ */
+
+static int 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(hostmatch(hostname,match_pattern) == CURL_HOST_MATCH)
+    return 1;
+  return 0;
+}

sample/hostcheck.h

@@ -0,0 +1,30 @@
+#ifndef HEADER_CURL_HOSTCHECK_H
+#define HEADER_CURL_HOSTCHECK_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2012, Daniel Stenberg, <[email protected]>, 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.
+ *
+ ***************************************************************************/
+
+#define CURL_HOST_NOMATCH 0
+#define CURL_HOST_MATCH   1
+int Curl_cert_hostcheck(const char *match_pattern, const char *hostname);
+
+#endif /* HEADER_CURL_HOSTCHECK_H */
+

sample/include.am

@@ -21,10 +21,13 @@ sample_le_proxy_INCLUDES = $(OPENSSL_INCS)
 SAMPLES += sample/https-client
 sample_https_client_SOURCES = \
 	sample/https-client.c \
+	sample/hostcheck.c \
 	sample/openssl_hostname_validation.c
 sample_https_client_LDADD = libevent.la libevent_openssl.la ${OPENSSL_LIBS} ${OPENSSL_LIBADD}
 sample_https_client_INCLUDES = $(OPENSSL_INCS)
-noinst_HEADERS += sample/openssl_hostname_validation.h
+noinst_HEADERS += \
+	sample/hostcheck.h \
+	sample/openssl_hostname_validation.h
 endif
 
 noinst_PROGRAMS += $(SAMPLES)

sample/openssl_hostname_validation.c

@@ -39,7 +39,7 @@ SOFTWARE.
 #include <openssl/ssl.h>
 
 #include "openssl_hostname_validation.h"
-
+#include "hostcheck.h"
 
 #define HOSTNAME_MAX_SIZE 255
 
@@ -82,7 +82,7 @@ static HostnameValidationResult matches_common_name(const char *hostname, const
         }
 
         // Compare expected hostname with the CN
-        if (strcasecmp(hostname, common_name_str) == 0) {
+        if (Curl_cert_hostcheck(common_name_str, hostname) == CURL_HOST_MATCH) {
                 return MatchFound;
         }
         else {
@@ -126,7 +126,8 @@ static HostnameValidationResult matches_subject_alternative_name(const char *hos
                                 break;
                         }
                         else { // Compare expected hostname with the DNS name
-                                if (strcasecmp(hostname, dns_name) == 0) {
+                                if (Curl_cert_hostcheck(dns_name, hostname)
+                                    == CURL_HOST_MATCH) {
                                         result = MatchFound;
                                         break;
                                 }