Improve looks_like_ip_address for IPv6 addresses, and add tests

src/core/tsi/ssl_transport_security.c

@@ -206,13 +206,16 @@ static void ssl_info_callback(const SSL *ssl, int where, int ret) {
 }
 
 /* Returns 1 if name looks like an IP address, 0 otherwise.
-   This is a very rough heuristic as it does not handle IPV6 or things like:
-   0300.0250.00.01, 0xC0.0Xa8.0x0.0x1, 000030052000001, 0xc0.052000001 */
+   This is a very rough heuristic, and only handles IPv6 in hexadecimal form. */
 static int looks_like_ip_address(const char *name) {
   size_t i;
   size_t dot_count = 0;
   size_t num_size = 0;
   for (i = 0; i < strlen(name); i++) {
+    if (name[i] == ':') {
+      /* IPv6 Address in hexadecimal form, : is not allowed in DNS names. */
+      return 1;
+    }
     if (name[i] >= '0' && name[i] <= '9') {
       if (num_size > 3) return 0;
       num_size++;

src/core/tsi/ssl_transport_security.h

@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015, Google Inc.
+ * Copyright 2015-2016, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without

test/core/tsi/transport_security_test.c

@@ -1,6 +1,6 @@
 /*
  *
- * Copyright 2015, Google Inc.
+ * Copyright 2015-2016, Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -194,6 +194,13 @@ const cert_name_test_entry cert_name_test_entries[] = {
     {0, "173.194.195.139", "foo.example.com", NULL, "8.8.8.8,8.8.4.4"},
     {1, "173.194.195.139", "foo.example.com", NULL, "8.8.8.8,173.194.195.139"},
     {0, "173.194.195.139", "foo.example.com", NULL, "173.194.195.13"},
+    {0, "2001:db8:a0b:12f0::1", "foo.example.com", NULL, "173.194.195.13"},
+    {1, "2001:db8:a0b:12f0::1", "foo.example.com", NULL,
+     "2001:db8:a0b:12f0::1"},
+    {0, "2001:db8:a0b:12f0::1", "foo.example.com", NULL,
+     "2001:db8:a0b:12f0::2"},
+    {1, "2001:db8:a0b:12f0::1", "foo.example.com", NULL,
+     "2001:db8:a0b:12f0::2,2001:db8:a0b:12f0::1,8.8.8.8"},
 };
 
 typedef struct name_list {