ae361ce19f
The routing algorithm must be able to decide if a fragment can be merged with the missing part and still be passed to a forwarding interface. The fragments can only differ by one byte in case that the original payload had an uneven length. In that situation the sender has to inform all possible receivers that the tail is one byte longer using the flag UNI_FRAG_LARGETAIL. The combination of UNI_FRAG_LARGETAIL and UNI_FRAG_HEAD flag makes it possible to calculate the correct length for even and uneven sized payloads. The original formula missed to add the unicast header at all and forgot to remove the fragment header of the second fragment. This made the results highly unreliable and only useful for machines with large differences between the configured MTUs. Reported-by: Russell Senior <russell@personaltelco.net> Reported-by: Marek Lindner <lindner_marek@yahoo.de> Signed-off-by: Sven Eckelmann <sven@narfation.org>
58 lines
1.9 KiB
C
58 lines
1.9 KiB
C
/*
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* Copyright (C) 2010 B.A.T.M.A.N. contributors:
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*
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* Andreas Langer
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA
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*
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*/
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#ifndef _NET_BATMAN_ADV_UNICAST_H_
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#define _NET_BATMAN_ADV_UNICAST_H_
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#include "packet.h"
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#define FRAG_TIMEOUT 10000 /* purge frag list entrys after time in ms */
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#define FRAG_BUFFER_SIZE 6 /* number of list elements in buffer */
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int frag_reassemble_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
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struct sk_buff **new_skb);
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void frag_list_free(struct list_head *head);
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int unicast_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv);
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int frag_send_skb(struct sk_buff *skb, struct bat_priv *bat_priv,
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struct batman_if *batman_if, uint8_t dstaddr[]);
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static inline int frag_can_reassemble(struct sk_buff *skb, int mtu)
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{
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struct unicast_frag_packet *unicast_packet;
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int uneven_correction = 0;
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unsigned int merged_size;
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unicast_packet = (struct unicast_frag_packet *)skb->data;
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if (unicast_packet->flags & UNI_FRAG_LARGETAIL) {
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if (unicast_packet->flags & UNI_FRAG_HEAD)
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uneven_correction = 1;
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else
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uneven_correction = -1;
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}
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merged_size = (skb->len - sizeof(struct unicast_frag_packet)) * 2;
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merged_size += sizeof(struct unicast_packet) + uneven_correction;
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return merged_size <= mtu;
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}
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#endif /* _NET_BATMAN_ADV_UNICAST_H_ */
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