148 lines
4.8 KiB
C
148 lines
4.8 KiB
C
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// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil -*- (for GNU Emacs)
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//
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// Copyright (c) 1998-2000 Microsoft Corporation
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//
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// This file is part of the Microsoft Research IPv6 Network Protocol Stack.
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// You should have received a copy of the Microsoft End-User License Agreement
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// for this software along with this release; see the file "license.txt".
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// If not, please see http://www.research.microsoft.com/msripv6/license.htm,
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// or write to Microsoft Research, One Microsoft Way, Redmond, WA 98052-6399.
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//
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// Abstract:
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//
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// IPv6 fragmentation/reassembly definitions.
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//
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#ifndef FRAGMENT_H_INCLUDED
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#define FRAGMENT_H_INCLUDED 1
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//
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// Structure used to link fragments together.
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//
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// The fragment data follows the shim structure in memory.
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//
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typedef struct PacketShim {
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struct PacketShim *Next; // Next packet on list.
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ushort Len;
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ushort Offset;
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} PacketShim;
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__inline uchar *
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PacketShimData(PacketShim *shim)
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{
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return (uchar *)(shim + 1);
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}
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//
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// Structure used to keep track of the fragments
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// being reassembled into a single IPv6 datagram.
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//
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// REVIEW: Some of these fields are bigger than they need to be.
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//
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struct Reassembly {
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struct Reassembly *Next, *Prev; // Protected by global reassembly lock.
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KSPIN_LOCK Lock; // Protects reassembly fields below.
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uint State; // See values below.
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IPv6Header IPHdr; // Copy of original IP header.
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Interface *IF; // Does not hold a reference.
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ulong Id; // Unique (along w/ addrs) datagram identifier.
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uchar *UnfragData; // Pointer to unfragmentable data.
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ushort UnfragmentLength; // Length of the unfragmentable part.
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ushort Timer; // Time to expiration in ticks (see IPv6Timeout).
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uint DataLength; // Length of the fragmentable part.
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PacketShim *ContigList; // Sorted, contiguous frags (from offset zero).
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PacketShim *ContigEnd; // Last shim on ContigList (for quick access).
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PacketShim *GapList; // Other fragments (sorted but non-contiguous).
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uint Flags; // Packet flags.
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uint Size; // Amount of memory consumed in this reassembly.
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ushort Marker; // The current marker for contiguous data.
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ushort MaxGap; // Largest data offset in the gap list.
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ushort NextHeaderOffset; // Offset from IPHdr to pre-FH NextHeader field.
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uchar NextHeader; // Header type following the fragment header.
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};
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//
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// A reassembly starts in REASSEMBLY_STATE_NORMAL.
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// If you want to remove it, then change the state
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// to REASSEMBLY_STATE_DELETING. This prevents someone else
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// from freeing it while you unlock the reassembly,
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// get the global reassembly list lock, and relock the assembly.
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// Someone else can remove the deleting reassembly
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// from the global list, in which case the state becomes
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// REASSEMBLY_STATE_REMOVED.
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//
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#define REASSEMBLY_STATE_NORMAL 0
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#define REASSEMBLY_STATE_DELETING 1
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#define REASSEMBLY_STATE_REMOVED 2
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//
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// There are denial-of-service issues with reassembly.
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// We limit the total amount of memory in the reassembly list.
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// If we get fragments that cause us to exceed the limit,
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// we remove old reassemblies.
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//
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// The locking order is
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// 1. Global reassembly list lock.
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// 2. Individual reassembly record locks.
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// 3. Reassembly list size lock.
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//
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extern struct ReassemblyList {
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KSPIN_LOCK Lock; // Protects Reassembly List.
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Reassembly *First; // List of packets being reassembled.
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Reassembly *Last;
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KSPIN_LOCK LockSize; // Protects the Size field.
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uint Size; // Total size of the waiting fragments.
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uint Limit; // Upper bound for Size.
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} ReassemblyList;
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#define SentinelReassembly ((Reassembly *)&ReassemblyList.First)
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//
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// Per-packet and per-fragment overhead sizes.
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// These are in addition to the actual size of the buffered data.
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// They should be at least as large as the Reassembly
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// and PacketShim struct sizes.
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//
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#define REASSEMBLY_SIZE_PACKET 1024
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#define REASSEMBLY_SIZE_FRAG 256
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#define DEFAULT_REASSEMBLY_TIMEOUT IPv6TimerTicks(60) // 60 seconds.
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extern Reassembly *
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FragmentLookup(Interface *IF, ulong Id,
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const IPv6Addr *Source, const IPv6Addr *Dest);
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extern void
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RemoveReassembly(Reassembly *Reass);
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extern void
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DeleteReassembly(Reassembly *Reass);
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extern void
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AddToReassemblyList(Reassembly *Reass);
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extern void
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DeleteFromReassemblyList(Reassembly *Reass);
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extern void
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IncreaseReassemblySize(Reassembly *Reass, uint Size);
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extern void
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CheckReassemblyQuota(Reassembly *Reass);
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extern void
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ReassemblyTimeout(void);
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extern void
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ReassembleDatagram(IPv6Packet *Packet, Reassembly *Reass);
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extern IPv6Packet *
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CreateFragmentPacket(Reassembly *Reass);
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#endif // FRAGMENT_H_INCLUDED
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