patch.diff

diff --git a/msgenu.h b/msgenu.h
index f61fe77a..aa18cbf0 100644
--- a/msgenu.h
+++ b/msgenu.h
@@ -2186,7 +2186,8 @@ LOGM_DLL_IMPORT int  panel_command_capture( char* cmd, char** resp );
 #define HHC03808 "%1d:%04X %s: %s: Cannot unregister guest IP address %s"
 #define HHC03809 "%1d:%04X %s: %s: Requested MTU %s too large; decreasing to %s bytes"
 #define HHC03810 "%1d:%04X %s: %s: Input dropped: %s"
-//efine HHC03811 - HHC03849 (available)
+#define HHC03811 "%1d:%04X %s: %s: Output dropped: %s"
+//efine HHC03812 - HHC03849 (available)
 
 //efine HHC03850 - HHC03899 (available)
 
diff --git a/qeth.c b/qeth.c
index aab6fe80..67ab19bd 100644
--- a/qeth.c
+++ b/qeth.c
@@ -3337,44 +3337,58 @@ static QRC write_buffered_packets( DEVBLK* dev, OSA_GRP *grp,
         pkt    = dev->buf;
         pktlen = dev->buflen;
 
-        /* I know the following looks pretty weird but it seems to be         */
-        /* necessary when using IPv6 over layer 3. IPv6 uses ICMPv6 Neighbor  */
-        /* Solicitation (NS) & Neighbor Advertisment (NA) to determine the    */
-        /* link layer address (i.e. Ethernet MAC) for an IPv6 address. When   */
-        /* the guest sends out a NS, this function sends the packet over the  */
-        /* tun to the host, whereupon the host duly ignores the packet. Hence */
-        /* this function, and function process_l3_icmpv6_packet, responds to  */
-        /* the NS with a NA. It seems that the NA must contain a link local   */
-        /* address, otherwise the guest ignores the packet. However, after    */
-        /* the guest has received an NA with a link local address every IPv6  */
-        /* packet from the guest is an Ethernet frame containing the IPv6     */
-        /* packet. Perhaps that's how OSD's actually work? IPv6 packets to    */
-        /* the guest don't need to be Ethernet frames.                        */
-        /*                                                                    */
-        /* Originally the whole of this section of code was surrounded by an  */
-        /* '#if defined(ENABLE_IPV6)' and '#endif'. However, implementing     */
-        /* zLinuz layer 3 support showed that zLinux emmitted IPv4 ARP        */
-        /* frames, which if sent to the tun interface, upset the tun, hence   */
-        /* the dropthishing checking.                                         */
-        /*                                                                    */
-        dropthisthing = FALSE;
-        if (grp->l3)
-        {
-          eth = (ETHFRM*)pkt;
-          if (memcmp( &eth->bSrcMAC[0], &grp->iMAC, IFHWADDRLEN ) == 0)
-          {
-            FETCH_HW( hwEthernetType, eth->hwEthernetType );
-            if (hwEthernetType == ETH_TYPE_IP || hwEthernetType == ETH_TYPE_IPV6)
-            {
-              pkt += sizeof(ETHFRM);
-              pktlen -= sizeof(ETHFRM);
-            } else {
-              dropthisthing = TRUE;
-            }
-          }
-        }
-
-        if (dropthisthing == TRUE) continue;
+       /*                      PROGRAMMING NOTE                              */
+       /*                                                                    */
+       /* I know the following looks pretty weird but it seems to be         */
+       /* necessary when using IPv6 over layer 3. IPv6 uses ICMPv6 Neighbor  */
+       /* Solicitation (NS) & Neighbor Advertisment (NA) to determine the    */
+       /* link layer address (i.e. Ethernet MAC) for an IPv6 address. When   */
+       /* the guest sends out a NS, this function sends the packet over the  */
+       /* tun to the host, whereupon the host duly ignores the packet. Hence */
+       /* this function, and function process_l3_icmpv6_packet, responds to  */
+       /* the NS with a NA. It seems that the NA must contain a link local   */
+       /* address, otherwise the guest ignores the packet. However, after    */
+       /* the guest has received an NA with a link local address every IPv6  */
+       /* packet from the guest is an Ethernet frame containing the IPv6     */
+       /* packet. Perhaps that's how OSD's actually work? IPv6 packets to    */
+       /* the guest don't need to be Ethernet frames.                        */
+       /*                                                                    */
+       /* Originally the whole of this section of code was surrounded by an  */
+       /* '#if defined(ENABLE_IPV6)' and '#endif'. However, implementing     */
+       /* zLinuz layer 3 support showed that zLinux emmitted IPv4 ARP        */
+       /* frames, which if sent to the tun interface, upset the tun, hence   */
+       /* the following special handling.                                    */
+       /*                                                                    */
+       if (grp->l3)
+       {
+         /* Might this be a L2 IPv6 Ethernet Frame? (and not an L3 IP packet?)
+           (Refer to PROGRAMMING NOTE just above regarding IPv6 over layer 3)
+         */
+         if (HDR_ID_LAYER2 == hdr_id)
+         {
+           eth = (ETHFRM*) pkt;
+           FETCH_HW( hwEthernetType, eth->hwEthernetType );
+           if (1
+               && ETH_TYPE_IP   != hwEthernetType
+               && ETH_TYPE_IPV6 != hwEthernetType
+           )
+           {
+             /* Can't write L2 Ethernet frame to L3 tun device! */
+             dev->qdio.dropcnt++;
+             if (grp->debugmask & DBGQETHDROP)
+             {
+               // "%1d:%04X %s: %s: Output dropped: %s"
+               WRMSG( HHC03811, "W", LCSS_DEVNUM,
+                 dev->typname, grp->ttifname, "L2 frame on tun device" );
+             }
+             continue; /* (don't write this packet) */
+           }
+       
+           /* Bump past L2 Ethernet header to actual L3 IP packet */
+           pkt    += sizeof( ETHFRM );
+           pktlen -= sizeof( ETHFRM );
+         }
+       }
 
         /* Debugging */
         if (grp->debugmask & DBGQETHPACKET)