IPv6FragBuf Class Reference

#include <IPv6FragBuf.h>

List of all members.

---

Detailed Description

Reassembly buffer for fragmented IPv6 datagrams.

Public Member Functions
	IPv6FragBuf ()
	~IPv6FragBuf ()
void	init (ICMPv6 *icmp)
IPv6Datagram *	addFragment (IPv6Datagram *datagram, IPv6FragmentHeader *fh, simtime_t now)
void	purgeStaleFragments (simtime_t lastupdate)
Protected Types
typedef std::map< Key, DatagramBuffer >	Buffers
Protected Attributes
Buffers	bufs
ICMPv6 *	icmpModule
Classes
struct	DatagramBuffer
struct	Key

---

Member Typedef Documentation

typedef std::map<Key,DatagramBuffer> IPv6FragBuf::Buffers [protected]

---

Constructor & Destructor Documentation

IPv6FragBuf::IPv6FragBuf (   )

Ctor. { icmpModule = NULL; }

IPv6FragBuf::~IPv6FragBuf (   )

Dtor. { }

---

Member Function Documentation

IPv6Datagram * IPv6FragBuf::addFragment (  IPv6Datagram *  datagram, IPv6FragmentHeader *  fh, simtime_t  now )

Takes a fragment and inserts it into the reassembly buffer. If this fragment completes a datagram, the full reassembled datagram is returned, otherwise NULL. { // find datagram buffer Key key; key.id = fh->identification(); key.src = datagram->srcAddress(); key.dest = datagram->destAddress(); Buffers::iterator i = bufs.find(key); DatagramBuffer *buf = NULL; if (i==bufs.end()) { // this is the first fragment of that datagram, create reassembly buffer for it buf = &bufs[key]; buf->datagram = NULL; } else { // use existing buffer buf = &(i->second); } // add fragment into reassembly buffer // FIXME next lines aren't correct: check 4.5 of RFC 2460 regarding Unfragmentable part, Fragmentable part, etc int bytes = datagram->byteLength() - datagram->calculateHeaderByteLength(); bool isComplete = buf->buf.addFragment(fh->fragmentOffset(), fh->fragmentOffset() + bytes, !fh->moreFragments()); // store datagram. Only one fragment carries the actual modelled // content (encapsulatedMsg()), other (empty) ones are only // preserved so that we can send them in ICMP if reassembly times out. if (datagram->encapsulatedMsg()) { delete buf->datagram; buf->datagram = datagram; } else { delete datagram; } // do we have the complete datagram? if (isComplete) { // datagram complete: deallocate buffer and return complete datagram IPv6Datagram *ret = buf->datagram; ret->setByteLength(ret->calculateHeaderByteLength()+buf->buf.totalLength()); // FIXME cf with 4.5 of RFC 2460 bufs.erase(i); return ret; } else { // there are still missing fragments buf->lastupdate = now; return NULL; } }

void IPv6FragBuf::init (  ICMPv6 *  icmp  )

Initialize fragmentation buffer. ICMP module is needed for sending TIME_EXCEEDED ICMP message in purgeStaleFragments(). { icmpModule = icmp; }

void IPv6FragBuf::purgeStaleFragments (  simtime_t  lastupdate  )

Throws out all fragments which are incomplete and their last update (last fragment arrival) was before "lastupdate", and sends ICMP TIME EXCEEDED message about them. Timeout should be between 60 seconds and 120 seconds (RFC1122). This method should be called more frequently, maybe every 10..30 seconds or so. { // this method shouldn't be called too often because iteration on // an std::map is *very* slow... ASSERT(icmpModule); for (Buffers::iterator i=bufs.begin(); i!=bufs.end(); ) { // if too old, remove it DatagramBuffer& buf = i->second; if (buf.lastupdate < lastupdate) { // send ICMP error EV << "datagram fragment timed out in reassembly buffer, sending ICMP_TIME_EXCEEDED\n"; icmpModule->sendErrorMessage(buf.datagram, ICMPv6_TIME_EXCEEDED, 0); // delete Buffers::iterator oldi = i++; bufs.erase(oldi); } else { ++i; } } }

---

Member Data Documentation

Buffers IPv6FragBuf::bufs [protected]

ICMPv6* IPv6FragBuf::icmpModule [protected]

---

The documentation for this class was generated from the following files:

• IPv6FragBuf.h
• IPv6FragBuf.cc

---