hostcheck: fixed to not touch used input strings

Avoids the need to clone the strings before check, thus avoiding
mallocs, which for cases where there are many SAN names in a cert could
end up numerous.

Closes #8321

lib/hostcheck.c

@@ -33,6 +33,7 @@
 #ifdef HAVE_NETINET_IN6_H
 #include <netinet/in6.h>
 #endif
+#include "curl_memrchr.h"
 
 #include "hostcheck.h"
 #include "strcase.h"
@@ -42,6 +43,16 @@
 /* The last #include file should be: */
 #include "memdebug.h"
 
+/* check the two input strings with given length, but do not
+   assume they end in nul-bytes */
+static bool pmatch(const char *hostname, size_t hostlen,
+                   const char *pattern, size_t patternlen)
+{
+  if(hostlen != patternlen)
+    return FALSE;
+  return strncasecompare(hostname, pattern, hostlen);
+}
+
 /*
  * Match a hostname against a wildcard pattern.
  * E.g.
@@ -58,85 +69,70 @@
  * apparent distinction between a name and an IP. We need to detect the use of
  * an IP address and not wildcard match on such names.
  *
- * NOTE: hostmatch() gets called with copied buffers so that it can modify the
- * contents at will.
+ * Return TRUE on a match. FALSE if not.
  */
 
-static int hostmatch(char *hostname, char *pattern)
+static bool hostmatch(const char *hostname, const char *pattern)
 {
-  const char *pattern_label_end, *pattern_wildcard, *hostname_label_end;
-  int wildcard_enabled;
+  const char *pattern_label_end, *wildcard, *hostname_label_end;
   size_t prefixlen, suffixlen;
 
   /* normalize pattern and hostname by stripping off trailing dots */
-  size_t len = strlen(hostname);
-  if(hostname[len-1]=='.')
-    hostname[len-1] = 0;
-  len = strlen(pattern);
-  if(pattern[len-1]=='.')
-    pattern[len-1] = 0;
+  size_t patternlen;
+  size_t hostlen = strlen(hostname);
+  if(hostname[hostlen-1]=='.')
+    hostlen--;
+  patternlen = strlen(pattern);
+  if(pattern[patternlen-1]=='.')
+    patternlen--;
 
-  pattern_wildcard = strchr(pattern, '*');
-  if(!pattern_wildcard)
-    return strcasecompare(pattern, hostname) ?
-      CURL_HOST_MATCH : CURL_HOST_NOMATCH;
+  wildcard = memchr(pattern, '*', patternlen);
+  if(!wildcard)
+    return pmatch(hostname, hostlen, pattern, patternlen);
 
   /* detect IP address as hostname and fail the match if so */
   if(Curl_host_is_ipnum(hostname))
-    return CURL_HOST_NOMATCH;
+    return FALSE;
 
-  /* We require at least 2 dots in pattern to avoid too wide wildcard
+  /* We require at least 2 dots in the pattern to avoid too wide wildcard
      match. */
-  wildcard_enabled = 1;
-  pattern_label_end = strchr(pattern, '.');
-  if(!pattern_label_end || !strchr(pattern_label_end + 1, '.') ||
-     pattern_wildcard > pattern_label_end ||
-     strncasecompare(pattern, "xn--", 4)) {
-    wildcard_enabled = 0;
+  pattern_label_end = memchr(pattern, '.', patternlen);
+  if(!pattern_label_end ||
+     (memrchr(pattern, '.', patternlen) == pattern_label_end) ||
+     strncasecompare(pattern, "xn--", 4))
+    return pmatch(hostname, hostlen, pattern, patternlen);
+
+  hostname_label_end = memchr(hostname, '.', hostlen);
+  if(!hostname_label_end)
+    return FALSE;
+  else {
+    size_t skiphost = hostname_label_end - hostname;
+    size_t skiplen = pattern_label_end - pattern;
+    if(!pmatch(hostname_label_end, hostlen - skiphost,
+               pattern_label_end, patternlen - skiplen))
+      return FALSE;
   }
-  if(!wildcard_enabled)
-    return strcasecompare(pattern, hostname) ?
-      CURL_HOST_MATCH : CURL_HOST_NOMATCH;
-
-  hostname_label_end = strchr(hostname, '.');
-  if(!hostname_label_end ||
-     !strcasecompare(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;
+    return FALSE;
 
-  prefixlen = pattern_wildcard - pattern;
-  suffixlen = pattern_label_end - (pattern_wildcard + 1);
+  prefixlen = wildcard - pattern;
+  suffixlen = pattern_label_end - (wildcard + 1);
   return strncasecompare(pattern, hostname, prefixlen) &&
-    strncasecompare(pattern_wildcard + 1, hostname_label_end - suffixlen,
-                    suffixlen) ?
-    CURL_HOST_MATCH : CURL_HOST_NOMATCH;
+    strncasecompare(wildcard + 1, hostname_label_end - suffixlen,
+                    suffixlen) ? TRUE : FALSE;
 }
 
-int Curl_cert_hostcheck(const char *match_pattern, const char *hostname)
+/*
+ * Curl_cert_hostcheck() returns TRUE if a match and FALSE if not.
+ */
+bool Curl_cert_hostcheck(const char *match, const char *hostname)
 {
-  int res = 0;
-  if(!match_pattern || !*match_pattern ||
-      !hostname || !*hostname) /* sanity check */
-    ;
-  else {
-    char *matchp = strdup(match_pattern);
-    if(matchp) {
-      char *hostp = strdup(hostname);
-      if(hostp) {
-        if(hostmatch(hostp, matchp) == CURL_HOST_MATCH)
-          res = 1;
-        free(hostp);
-      }
-      free(matchp);
-    }
-  }
-
-  return res;
+  if(match && *match && hostname && *hostname)
+    return hostmatch(hostname, match);
+  return FALSE;
 }
 
 #endif /* OPENSSL, GSKIT or schannel+wince */

lib/hostcheck.h

@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2022, 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
@@ -24,8 +24,7 @@
 
 #include <curl/curl.h>
 
-#define CURL_HOST_NOMATCH 0
-#define CURL_HOST_MATCH   1
-int Curl_cert_hostcheck(const char *match_pattern, const char *hostname);
+/* returns TRUE if there's a match */
+bool Curl_cert_hostcheck(const char *match_pattern, const char *hostname);
 
 #endif /* HEADER_CURL_HOSTCHECK_H */

lib/vtls/schannel_verify.c

@@ -7,7 +7,7 @@
  *
  * Copyright (C) 2012 - 2016, Marc Hoersken, <info@marc-hoersken.de>
  * Copyright (C) 2012, Mark Salisbury, <mark.salisbury@hp.com>
- * Copyright (C) 2012 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 2012 - 2022, 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
@@ -520,10 +520,7 @@ static CURLcode verify_host(struct Curl_easy *data,
       result = CURLE_OUT_OF_MEMORY;
     }
     else {
-      int match_result;
-
-      match_result = Curl_cert_hostcheck(cert_hostname, conn_hostname);
-      if(match_result == CURL_HOST_MATCH) {
+      if(Curl_cert_hostcheck(cert_hostname, conn_hostname)) {
         infof(data,
               "schannel: connection hostname (%s) validated "
               "against certificate name (%s)",