ikev1: Add fragmentation support for Windows peers
authorVolker Rümelin <vr_strongswan@t-online.de>
Thu, 25 Sep 2014 07:18:17 +0000 (09:18 +0200)
committerTobias Brunner <tobias@strongswan.org>
Fri, 10 Oct 2014 08:54:37 +0000 (10:54 +0200)
I still think ipsec/l2tp with fragmentation support is a useful
fallback option in case the Windows IKEv2 connection fails because
of fragmentation problems.

Tested with Windows XP, 7 and 8.1.

src/libcharon/sa/ike_sa.c
src/libcharon/sa/ike_sa.h
src/libcharon/sa/ikev1/tasks/isakmp_vendor.c

index 8b659c0..0d4aa0c 100644 (file)
  * for more details.
  */
 
+/*
+ * Copyright (c) 2014 Volker Rümelin
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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. 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.
+ */
+
 #include <string.h>
 #include <sys/stat.h>
 #include <errno.h>
@@ -1024,6 +1046,14 @@ METHOD(ike_sa_t, generate_message_fragmented, status_t,
                                break;
                        case FRAGMENTATION_YES:
                                use_frags = supports_extension(this, EXT_IKE_FRAGMENTATION);
+                               if (use_frags && this->version == IKEV1 &&
+                                       supports_extension(this, EXT_MS_WINDOWS))
+                               {
+                                       /* It seems Windows 7 and 8 peers only accept proprietary
+                                        * fragmented messages if they expect certificates. */
+                                       use_frags = message->get_payload(message,
+                                                                                                        PLV1_CERTIFICATE) != NULL;
+                               }
                                break;
                        default:
                                break;
index f04fab0..c72d873 100644 (file)
@@ -102,7 +102,7 @@ enum ike_extension_t {
        EXT_EAP_ONLY_AUTHENTICATION = (1<<5),
 
        /**
-        * peer is probably a Windows RAS client
+        * peer is probably a Windows RAS client
         */
        EXT_MS_WINDOWS = (1<<6),
 
index 426c4bd..0162fd8 100644 (file)
@@ -15,7 +15,7 @@
  */
 
 /*
- * Copyright (C) 2012 Volker Rümelin
+ * Copyright (C) 2012-2014 Volker Rümelin
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -106,10 +106,15 @@ static struct {
          "\x12\xf5\xf2\x8c\x45\x71\x68\xa9\x70\x2d\x9f\xe2\x74\xcc\x01\x00"},
 
        /* Proprietary IKE fragmentation extension. Capabilities are handled
-        * specially on receipt of this VID. */
+        * specially on receipt of this VID. Windows peers send this VID
+        * without capabilities, but accept it with and without capabilities. */
        { "FRAGMENTATION", EXT_IKE_FRAGMENTATION, FALSE, 20,
          "\x40\x48\xb7\xd5\x6e\xbc\xe8\x85\x25\xe7\xde\x7f\x00\xd6\xc2\xd3\x80\x00\x00\x00"},
 
+       /* Windows peers send this VID and a version number */
+       { "MS NT5 ISAKMPOAKLEY", EXT_MS_WINDOWS, FALSE, 20,
+         "\x1e\x2b\x51\x69\x05\x99\x1c\x7d\x7c\x96\xfc\xbf\xb5\x87\xe4\x61\x00\x00\x00\x00"},
+
 }, vendor_natt_ids[] = {
 
        /* NAT-Traversal VIDs ordered by preference */
@@ -167,15 +172,27 @@ static struct {
  */
 static const u_int32_t fragmentation_ike = 0x80000000;
 
-/**
- * Check if the given vendor ID indicate support for fragmentation
- */
-static bool fragmentation_supported(chunk_t data, int i)
+static bool is_known_vid(chunk_t data, int i)
 {
-       if (vendor_ids[i].extension  == EXT_IKE_FRAGMENTATION &&
-               data.len == 20 && memeq(data.ptr, vendor_ids[i].id, 16))
+       switch (vendor_ids[i].extension)
        {
-               return untoh32(&data.ptr[16]) & fragmentation_ike;
+               case EXT_IKE_FRAGMENTATION:
+                       if (data.len >= 16 && memeq(data.ptr, vendor_ids[i].id, 16))
+                       {
+                               switch (data.len)
+                               {
+                                       case 16:
+                                               return TRUE;
+                                       case 20:
+                                               return untoh32(&data.ptr[16]) & fragmentation_ike;
+                               }
+                       }
+                       break;
+               case EXT_MS_WINDOWS:
+                       return data.len == 20 && memeq(data.ptr, vendor_ids[i].id, 16);
+               default:
+                       return chunk_equals(data, chunk_create(vendor_ids[i].id,
+                                                                                                  vendor_ids[i].len));
        }
        return FALSE;
 }
@@ -251,9 +268,7 @@ static void process(private_isakmp_vendor_t *this, message_t *message)
 
                        for (i = 0; i < countof(vendor_ids); i++)
                        {
-                               if (chunk_equals(data, chunk_create(vendor_ids[i].id,
-                                                                                                       vendor_ids[i].len)) ||
-                                       fragmentation_supported(data, i))
+                               if (is_known_vid(data, i))
                                {
                                        DBG1(DBG_IKE, "received %s vendor ID", vendor_ids[i].desc);
                                        if (vendor_ids[i].extension)