#include "lwip/opt.h"
#include "lwip/ip4_frag.h"
#include "lwip/def.h"
#include "lwip/inet_chksum.h"
#include "lwip/netif.h"
#include "lwip/stats.h"
#include "lwip/icmp.h"
#include <string.h>
#include "arch/bpstruct.h"
#include "arch/epstruct.h"

Data Structures
struct	ip_reass_helper

Macros
#define	IP_REASS_CHECK_OVERLAP 1

#define	IP_REASS_FREE_OLDEST 1

Functions
void	ip_reass_tmr (void)

struct pbuf *	ip4_reass (struct pbuf *p)

err_t	ip4_frag (struct pbuf p, struct netif netif, const ip4_addr_t *dest)

Detailed Description

This is the IPv4 packet segmentation and reassembly implementation.

Macro Definition Documentation

◆ IP_REASS_CHECK_OVERLAP

#define IP_REASS_CHECK_OVERLAP 1

The IP reassembly code currently has the following limitations:

IP header options are not supported
fragments must not overlap (e.g. due to different routes), currently, overlapping or duplicate fragments are thrown away if IP_REASS_CHECK_OVERLAP=1 (the default)!

Setting this to 0, you can turn off checking the fragments for overlapping regions. The code gets a little smaller. Only use this if you know that overlapping won't occur on your network!

◆ IP_REASS_FREE_OLDEST

#define IP_REASS_FREE_OLDEST 1

Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller. Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA is set to 1, so one datagram can be reassembled at a time, only.

Function Documentation

◆ ip4_frag()

err_t ip4_frag	(	struct pbuf *	p,
		struct netif *	netif,
		const ip4_addr_t *	dest
	)

Fragment an IP datagram if too large for the netif.

Chop the datagram in MTU sized chunks and send them in order by pointing PBUF_REFs into p.

Parameters

p	ip packet to send
netif	the netif on which to send
dest	destination ip address to which to send

Returns: ERR_OK if sent successfully, err_t otherwise

◆ ip4_reass()

struct pbuf* ip4_reass ( struct pbuf * p )

Reassembles incoming IP fragments into an IP datagram.

Parameters

p	points to a pbuf chain of the fragment

Returns: NULL if reassembly is incomplete, ? otherwise

◆ ip_reass_tmr()

void ip_reass_tmr ( void )

Reassembly timer base function for both NO_SYS == 0 and 1 (!).

Should be called every 1000 msec (defined by IP_TMR_INTERVAL).

Data Structures

Macros

Functions