ipv4_frag.c File Reference

IPv4 fragmentation and reassembly. More...

#include "core/net.h"
#include "core/ip.h"
#include "ipv4/ipv4.h"
#include "ipv4/ipv4_frag.h"
#include "ipv4/icmp.h"
#include "mibs/mib2_module.h"
#include "mibs/ip_mib_module.h"
#include "debug.h"

Go to the source code of this file.




error_t ipv4FragmentDatagram (NetInterface *interface, Ipv4PseudoHeader *pseudoHeader, uint16_t id, const NetBuffer *payload, size_t payloadOffset, uint_t flags)
 Fragment an IPv4 datagram into smaller packets. More...
void ipv4ReassembleDatagram (NetInterface *interface, const Ipv4Header *packet, size_t length)
 IPv4 datagram reassembly algorithm. More...
void ipv4FragTick (NetInterface *interface)
 Fragment reassembly timeout handler. More...
Ipv4FragDescipv4SearchFragQueue (NetInterface *interface, const Ipv4Header *packet)
 Search for a matching datagram in the reassembly queue. More...
void ipv4FlushFragQueue (NetInterface *interface)
 Flush IPv4 reassembly queue. More...
Ipv4HoleDescipv4FindHole (Ipv4FragDesc *frag, uint16_t offset)
 Retrieve hole descriptor. More...
void ipv4DumpHoleList (Ipv4FragDesc *frag)
 Dump hole descriptor list. More...


systime_t ipv4FragTickCounter

Detailed Description

IPv4 fragmentation and reassembly.


SPDX-License-Identifier: GPL-2.0-or-later

Copyright (C) 2010-2019 Oryx Embedded SARL. All rights reserved.

This file is part of CycloneTCP Open.

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.


The Internet Protocol (IP) implements datagram fragmentation, so that packets may be formed that can pass through a link with a smaller maximum transmission unit (MTU) than the original datagram size. Refer to the following RFCs for complete details:

  • RFC 791: Internet Protocol specification
  • RFC 815: IP datagram reassembly algorithms
Oryx Embedded SARL (www.oryx-embedded.com)

Definition in file ipv4_frag.c.

Macro Definition Documentation



Definition at line 41 of file ipv4_frag.c.

Function Documentation

◆ ipv4DumpHoleList()

void ipv4DumpHoleList ( Ipv4FragDesc frag)

Dump hole descriptor list.

[in]fragIPv4 fragment descriptor

Definition at line 653 of file ipv4_frag.c.

◆ ipv4FindHole()

Ipv4HoleDesc* ipv4FindHole ( Ipv4FragDesc frag,
uint16_t  offset 

Retrieve hole descriptor.

[in]fragIPv4 fragment descriptor
[in]offsetOffset of the hole
A pointer to the hole descriptor is returned if the specified offset is valid. Otherwise NULL is returned

Definition at line 641 of file ipv4_frag.c.

◆ ipv4FlushFragQueue()

void ipv4FlushFragQueue ( NetInterface interface)

Flush IPv4 reassembly queue.

[in]interfaceUnderlying network interface

Definition at line 620 of file ipv4_frag.c.

◆ ipv4FragmentDatagram()

error_t ipv4FragmentDatagram ( NetInterface interface,
Ipv4PseudoHeader pseudoHeader,
uint16_t  id,
const NetBuffer payload,
size_t  payloadOffset,
uint_t  flags 

Fragment an IPv4 datagram into smaller packets.

[in]interfaceUnderlying network interface
[in]pseudoHeaderIPv4 pseudo header
[in]idFragment identification
[in]payloadMulti-part buffer containing the payload
[in]payloadOffsetOffset to the first payload byte
[in]flagsSet of flags that influences the behavior of this function
Error code

Definition at line 71 of file ipv4_frag.c.

◆ ipv4FragTick()

void ipv4FragTick ( NetInterface interface)

Fragment reassembly timeout handler.

This routine must be periodically called by the TCP/IP stack to handle IPv4 fragment reassembly timeout

[in]interfaceUnderlying network interface

Definition at line 449 of file ipv4_frag.c.

◆ ipv4ReassembleDatagram()

void ipv4ReassembleDatagram ( NetInterface interface,
const Ipv4Header packet,
size_t  length 

IPv4 datagram reassembly algorithm.

[in]interfaceUnderlying network interface
[in]packetPointer to the IPv4 fragmented packet
[in]lengthPacket length including header and payload

Definition at line 179 of file ipv4_frag.c.

◆ ipv4SearchFragQueue()

Ipv4FragDesc* ipv4SearchFragQueue ( NetInterface interface,
const Ipv4Header packet 

Search for a matching datagram in the reassembly queue.

[in]interfaceUnderlying network interface
[in]packetIncoming IPv4 packet
Matching fragment descriptor

Definition at line 517 of file ipv4_frag.c.

Variable Documentation

◆ ipv4FragTickCounter

systime_t ipv4FragTickCounter

Definition at line 57 of file ipv4_frag.c.