Introducing helper function to validate IPv4 address strings.

src/common/util.c

@@ -957,8 +957,19 @@ string_is_key_value(int severity, const char *string)
   return 1;
 }
 
-/** Return true iff <b>string</b> is valid DNS name, as defined in
- * RFC 1035 Section 2.3.1.
+/** Return true if <b>string</b> represents a valid IPv4 adddress in
+ * 'a.b.c.d' form.
+ */
+int
+string_is_valid_ipv4_address(const char *string)
+{
+   struct sockaddr_in sockaddr;
+
+   return (tor_inet_pton(AF_INET,string,&sockaddr) == 1);
+}
+
+/** Return true iff <b>string</b> matches a pattern of DNS names
+ * that we allow Tor clients to connect to.
  */
 int
 string_is_valid_hostname(const char *string)
@@ -988,6 +999,10 @@ string_is_valid_hostname(const char *string)
 
    } SMARTLIST_FOREACH_END(c);
 
+   SMARTLIST_FOREACH_BEGIN(components, char *, c) {
+     tor_free(c);
+   } SMARTLIST_FOREACH_END(c);
+
    smartlist_free(components);
 
    return result;

src/common/util.h

@@ -228,6 +228,7 @@ const char *find_str_at_start_of_line(const char *haystack,
 int string_is_C_identifier(const char *string);
 int string_is_key_value(int severity, const char *string);
 int string_is_valid_hostname(const char *string);
+int string_is_valid_ipv4_address(const char *string);
 
 int tor_mem_is_zero(const char *mem, size_t len);
 int tor_digest_is_zero(const char *digest);

src/test/test_util.c

@@ -4138,9 +4138,9 @@ test_util_hostname_validation(void *arg)
   tt_assert(!string_is_valid_hostname("-torproject.org"));
   tt_assert(!string_is_valid_hostname("subdomain.-domain.org"));
   tt_assert(!string_is_valid_hostname("-subdomain.domain.org"));
-  
+
   // Hostnames cannot contain non-alphanumeric characters.
-  tt_assert(!string_is_valid_hostname("%%domain.\\org."));  
+  tt_assert(!string_is_valid_hostname("%%domain.\\org."));
   tt_assert(!string_is_valid_hostname("***x.net"));
   tt_assert(!string_is_valid_hostname("___abc.org"));
   tt_assert(!string_is_valid_hostname("\xff\xffxyz.org"));
@@ -4152,6 +4152,22 @@ test_util_hostname_validation(void *arg)
   return;
 }
 
+static void
+test_util_ipv4_validation(void *arg)
+{
+  (void)arg;
+
+  tt_assert(string_is_valid_ipv4_address("192.168.0.1"));
+  tt_assert(string_is_valid_ipv4_address("8.8.8.8"));
+
+  tt_assert(!string_is_valid_ipv4_address("abcd"));
+  tt_assert(!string_is_valid_ipv4_address("300.300.300.300"));
+  tt_assert(!string_is_valid_ipv4_address("8.8."));
+
+  done:
+  return;
+}
+
 struct testcase_t util_tests[] = {
   UTIL_LEGACY(time),
   UTIL_TEST(parse_http_time, 0),
@@ -4225,6 +4241,7 @@ struct testcase_t util_tests[] = {
     &socketpair_setup, (void*)"1" },
   UTIL_TEST(max_mem, 0),
   UTIL_TEST(hostname_validation, 0),
+  UTIL_TEST(ipv4_validation, 0),
   END_OF_TESTCASES
 };