NetServices -

Users » segundo » Code » NetServices

Dependents: TimeZoneDemo EthernetJackTestCode MMEx_Challenge ntp_mem ... more

lwip/core/ipv4/ip_frag.c@0:ac1725ba162c, 2010-11-09 (annotated)

Committer:: segundo
Date:: Tue Nov 09 20:54:15 2010 +0000
Revision:: 0:ac1725ba162c

Who changed what in which revision?

User	Revision	Line number	New contents of line
segundo	0:ac1725ba162c	1	/**
segundo	0:ac1725ba162c	2	* @file
segundo	0:ac1725ba162c	3	* This is the IPv4 packet segmentation and reassembly implementation.
segundo	0:ac1725ba162c	4	*
segundo	0:ac1725ba162c	5	*/
segundo	0:ac1725ba162c	6
segundo	0:ac1725ba162c	7	/*
segundo	0:ac1725ba162c	8	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
segundo	0:ac1725ba162c	9	* All rights reserved.
segundo	0:ac1725ba162c	10	*
segundo	0:ac1725ba162c	11	* Redistribution and use in source and binary forms, with or without modification,
segundo	0:ac1725ba162c	12	* are permitted provided that the following conditions are met:
segundo	0:ac1725ba162c	13	*
segundo	0:ac1725ba162c	14	* 1. Redistributions of source code must retain the above copyright notice,
segundo	0:ac1725ba162c	15	* this list of conditions and the following disclaimer.
segundo	0:ac1725ba162c	16	* 2. Redistributions in binary form must reproduce the above copyright notice,
segundo	0:ac1725ba162c	17	* this list of conditions and the following disclaimer in the documentation
segundo	0:ac1725ba162c	18	* and/or other materials provided with the distribution.
segundo	0:ac1725ba162c	19	* 3. The name of the author may not be used to endorse or promote products
segundo	0:ac1725ba162c	20	* derived from this software without specific prior written permission.
segundo	0:ac1725ba162c	21	*
segundo	0:ac1725ba162c	22	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
segundo	0:ac1725ba162c	23	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
segundo	0:ac1725ba162c	24	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
segundo	0:ac1725ba162c	25	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
segundo	0:ac1725ba162c	26	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
segundo	0:ac1725ba162c	27	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
segundo	0:ac1725ba162c	28	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
segundo	0:ac1725ba162c	29	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
segundo	0:ac1725ba162c	30	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
segundo	0:ac1725ba162c	31	* OF SUCH DAMAGE.
segundo	0:ac1725ba162c	32	*
segundo	0:ac1725ba162c	33	* This file is part of the lwIP TCP/IP stack.
segundo	0:ac1725ba162c	34	*
segundo	0:ac1725ba162c	35	* Author: Jani Monoses <jani@iv.ro>
segundo	0:ac1725ba162c	36	* Simon Goldschmidt
segundo	0:ac1725ba162c	37	* original reassembly code by Adam Dunkels <adam@sics.se>
segundo	0:ac1725ba162c	38	*
segundo	0:ac1725ba162c	39	*/
segundo	0:ac1725ba162c	40
segundo	0:ac1725ba162c	41	#include "lwip/opt.h"
segundo	0:ac1725ba162c	42	#include "lwip/ip_frag.h"
segundo	0:ac1725ba162c	43	#include "lwip/def.h"
segundo	0:ac1725ba162c	44	#include "lwip/inet_chksum.h"
segundo	0:ac1725ba162c	45	#include "lwip/netif.h"
segundo	0:ac1725ba162c	46	#include "lwip/snmp.h"
segundo	0:ac1725ba162c	47	#include "lwip/stats.h"
segundo	0:ac1725ba162c	48	#include "lwip/icmp.h"
segundo	0:ac1725ba162c	49
segundo	0:ac1725ba162c	50	#include <string.h>
segundo	0:ac1725ba162c	51
segundo	0:ac1725ba162c	52	#if IP_REASSEMBLY
segundo	0:ac1725ba162c	53	/**
segundo	0:ac1725ba162c	54	* The IP reassembly code currently has the following limitations:
segundo	0:ac1725ba162c	55	* - IP header options are not supported
segundo	0:ac1725ba162c	56	* - fragments must not overlap (e.g. due to different routes),
segundo	0:ac1725ba162c	57	* currently, overlapping or duplicate fragments are thrown away
segundo	0:ac1725ba162c	58	* if IP_REASS_CHECK_OVERLAP=1 (the default)!
segundo	0:ac1725ba162c	59	*
segundo	0:ac1725ba162c	60	* @todo: work with IP header options
segundo	0:ac1725ba162c	61	*/
segundo	0:ac1725ba162c	62
segundo	0:ac1725ba162c	63	/** Setting this to 0, you can turn off checking the fragments for overlapping
segundo	0:ac1725ba162c	64	* regions. The code gets a little smaller. Only use this if you know that
segundo	0:ac1725ba162c	65	* overlapping won't occur on your network! */
segundo	0:ac1725ba162c	66	#ifndef IP_REASS_CHECK_OVERLAP
segundo	0:ac1725ba162c	67	#define IP_REASS_CHECK_OVERLAP 1
segundo	0:ac1725ba162c	68	#endif /* IP_REASS_CHECK_OVERLAP */
segundo	0:ac1725ba162c	69
segundo	0:ac1725ba162c	70	/** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is
segundo	0:ac1725ba162c	71	* full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller.
segundo	0:ac1725ba162c	72	* Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA
segundo	0:ac1725ba162c	73	* is set to 1, so one datagram can be reassembled at a time, only. */
segundo	0:ac1725ba162c	74	#ifndef IP_REASS_FREE_OLDEST
segundo	0:ac1725ba162c	75	#define IP_REASS_FREE_OLDEST 1
segundo	0:ac1725ba162c	76	#endif /* IP_REASS_FREE_OLDEST */
segundo	0:ac1725ba162c	77
segundo	0:ac1725ba162c	78	#define IP_REASS_FLAG_LASTFRAG 0x01
segundo	0:ac1725ba162c	79
segundo	0:ac1725ba162c	80	/** This is a helper struct which holds the starting
segundo	0:ac1725ba162c	81	* offset and the ending offset of this fragment to
segundo	0:ac1725ba162c	82	* easily chain the fragments.
segundo	0:ac1725ba162c	83	* It has the same packing requirements as the IP header, since it replaces
segundo	0:ac1725ba162c	84	* the IP header in memory in incoming fragments (after copying it) to keep
segundo	0:ac1725ba162c	85	* track of the various fragments. (-> If the IP header doesn't need packing,
segundo	0:ac1725ba162c	86	* this struct doesn't need packing, too.)
segundo	0:ac1725ba162c	87	*/
segundo	0:ac1725ba162c	88	#ifdef PACK_STRUCT_USE_INCLUDES
segundo	0:ac1725ba162c	89	# include "arch/bpstruct.h"
segundo	0:ac1725ba162c	90	#endif
segundo	0:ac1725ba162c	91	PACK_STRUCT_BEGIN
segundo	0:ac1725ba162c	92	struct ip_reass_helper {
segundo	0:ac1725ba162c	93	PACK_STRUCT_FIELD(struct pbuf *next_pbuf);
segundo	0:ac1725ba162c	94	PACK_STRUCT_FIELD(u16_t start);
segundo	0:ac1725ba162c	95	PACK_STRUCT_FIELD(u16_t end);
segundo	0:ac1725ba162c	96	} PACK_STRUCT_STRUCT;
segundo	0:ac1725ba162c	97	PACK_STRUCT_END
segundo	0:ac1725ba162c	98	#ifdef PACK_STRUCT_USE_INCLUDES
segundo	0:ac1725ba162c	99	# include "arch/epstruct.h"
segundo	0:ac1725ba162c	100	#endif
segundo	0:ac1725ba162c	101
segundo	0:ac1725ba162c	102	#define IP_ADDRESSES_AND_ID_MATCH(iphdrA, iphdrB) \
segundo	0:ac1725ba162c	103	(ip_addr_cmp(&(iphdrA)->src, &(iphdrB)->src) && \
segundo	0:ac1725ba162c	104	ip_addr_cmp(&(iphdrA)->dest, &(iphdrB)->dest) && \
segundo	0:ac1725ba162c	105	IPH_ID(iphdrA) == IPH_ID(iphdrB)) ? 1 : 0
segundo	0:ac1725ba162c	106
segundo	0:ac1725ba162c	107	/* global variables */
segundo	0:ac1725ba162c	108	static struct ip_reassdata *reassdatagrams;
segundo	0:ac1725ba162c	109	static u16_t ip_reass_pbufcount;
segundo	0:ac1725ba162c	110
segundo	0:ac1725ba162c	111	/* function prototypes */
segundo	0:ac1725ba162c	112	static void ip_reass_dequeue_datagram(struct ip_reassdata ipr, struct ip_reassdata prev);
segundo	0:ac1725ba162c	113	static int ip_reass_free_complete_datagram(struct ip_reassdata ipr, struct ip_reassdata prev);
segundo	0:ac1725ba162c	114
segundo	0:ac1725ba162c	115	/**
segundo	0:ac1725ba162c	116	* Reassembly timer base function
segundo	0:ac1725ba162c	117	* for both NO_SYS == 0 and 1 (!).
segundo	0:ac1725ba162c	118	*
segundo	0:ac1725ba162c	119	* Should be called every 1000 msec (defined by IP_TMR_INTERVAL).
segundo	0:ac1725ba162c	120	*/
segundo	0:ac1725ba162c	121	void
segundo	0:ac1725ba162c	122	ip_reass_tmr(void)
segundo	0:ac1725ba162c	123	{
segundo	0:ac1725ba162c	124	struct ip_reassdata r, prev = NULL;
segundo	0:ac1725ba162c	125
segundo	0:ac1725ba162c	126	r = reassdatagrams;
segundo	0:ac1725ba162c	127	while (r != NULL) {
segundo	0:ac1725ba162c	128	/* Decrement the timer. Once it reaches 0,
segundo	0:ac1725ba162c	129	* clean up the incomplete fragment assembly */
segundo	0:ac1725ba162c	130	if (r->timer > 0) {
segundo	0:ac1725ba162c	131	r->timer--;
segundo	0:ac1725ba162c	132	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n",(u16_t)r->timer));
segundo	0:ac1725ba162c	133	prev = r;
segundo	0:ac1725ba162c	134	r = r->next;
segundo	0:ac1725ba162c	135	} else {
segundo	0:ac1725ba162c	136	/* reassembly timed out */
segundo	0:ac1725ba162c	137	struct ip_reassdata *tmp;
segundo	0:ac1725ba162c	138	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer timed out\n"));
segundo	0:ac1725ba162c	139	tmp = r;
segundo	0:ac1725ba162c	140	/* get the next pointer before freeing */
segundo	0:ac1725ba162c	141	r = r->next;
segundo	0:ac1725ba162c	142	/* free the helper struct and all enqueued pbufs */
segundo	0:ac1725ba162c	143	ip_reass_free_complete_datagram(tmp, prev);
segundo	0:ac1725ba162c	144	}
segundo	0:ac1725ba162c	145	}
segundo	0:ac1725ba162c	146	}
segundo	0:ac1725ba162c	147
segundo	0:ac1725ba162c	148	/**
segundo	0:ac1725ba162c	149	* Free a datagram (struct ip_reassdata) and all its pbufs.
segundo	0:ac1725ba162c	150	* Updates the total count of enqueued pbufs (ip_reass_pbufcount),
segundo	0:ac1725ba162c	151	* SNMP counters and sends an ICMP time exceeded packet.
segundo	0:ac1725ba162c	152	*
segundo	0:ac1725ba162c	153	* @param ipr datagram to free
segundo	0:ac1725ba162c	154	* @param prev the previous datagram in the linked list
segundo	0:ac1725ba162c	155	* @return the number of pbufs freed
segundo	0:ac1725ba162c	156	*/
segundo	0:ac1725ba162c	157	static int
segundo	0:ac1725ba162c	158	ip_reass_free_complete_datagram(struct ip_reassdata ipr, struct ip_reassdata prev)
segundo	0:ac1725ba162c	159	{
segundo	0:ac1725ba162c	160	u16_t pbufs_freed = 0;
segundo	0:ac1725ba162c	161	u8_t clen;
segundo	0:ac1725ba162c	162	struct pbuf *p;
segundo	0:ac1725ba162c	163	struct ip_reass_helper *iprh;
segundo	0:ac1725ba162c	164
segundo	0:ac1725ba162c	165	LWIP_ASSERT("prev != ipr", prev != ipr);
segundo	0:ac1725ba162c	166	if (prev != NULL) {
segundo	0:ac1725ba162c	167	LWIP_ASSERT("prev->next == ipr", prev->next == ipr);
segundo	0:ac1725ba162c	168	}
segundo	0:ac1725ba162c	169
segundo	0:ac1725ba162c	170	snmp_inc_ipreasmfails();
segundo	0:ac1725ba162c	171	#if LWIP_ICMP
segundo	0:ac1725ba162c	172	iprh = (struct ip_reass_helper *)ipr->p->payload;
segundo	0:ac1725ba162c	173	if (iprh->start == 0) {
segundo	0:ac1725ba162c	174	/* The first fragment was received, send ICMP time exceeded. */
segundo	0:ac1725ba162c	175	/* First, de-queue the first pbuf from r->p. */
segundo	0:ac1725ba162c	176	p = ipr->p;
segundo	0:ac1725ba162c	177	ipr->p = iprh->next_pbuf;
segundo	0:ac1725ba162c	178	/* Then, copy the original header into it. */
segundo	0:ac1725ba162c	179	SMEMCPY(p->payload, &ipr->iphdr, IP_HLEN);
segundo	0:ac1725ba162c	180	icmp_time_exceeded(p, ICMP_TE_FRAG);
segundo	0:ac1725ba162c	181	clen = pbuf_clen(p);
segundo	0:ac1725ba162c	182	LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
segundo	0:ac1725ba162c	183	pbufs_freed += clen;
segundo	0:ac1725ba162c	184	pbuf_free(p);
segundo	0:ac1725ba162c	185	}
segundo	0:ac1725ba162c	186	#endif /* LWIP_ICMP */
segundo	0:ac1725ba162c	187
segundo	0:ac1725ba162c	188	/* First, free all received pbufs. The individual pbufs need to be released
segundo	0:ac1725ba162c	189	separately as they have not yet been chained */
segundo	0:ac1725ba162c	190	p = ipr->p;
segundo	0:ac1725ba162c	191	while (p != NULL) {
segundo	0:ac1725ba162c	192	struct pbuf *pcur;
segundo	0:ac1725ba162c	193	iprh = (struct ip_reass_helper *)p->payload;
segundo	0:ac1725ba162c	194	pcur = p;
segundo	0:ac1725ba162c	195	/* get the next pointer before freeing */
segundo	0:ac1725ba162c	196	p = iprh->next_pbuf;
segundo	0:ac1725ba162c	197	clen = pbuf_clen(pcur);
segundo	0:ac1725ba162c	198	LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
segundo	0:ac1725ba162c	199	pbufs_freed += clen;
segundo	0:ac1725ba162c	200	pbuf_free(pcur);
segundo	0:ac1725ba162c	201	}
segundo	0:ac1725ba162c	202	/* Then, unchain the struct ip_reassdata from the list and free it. */
segundo	0:ac1725ba162c	203	ip_reass_dequeue_datagram(ipr, prev);
segundo	0:ac1725ba162c	204	LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= pbufs_freed);
segundo	0:ac1725ba162c	205	ip_reass_pbufcount -= pbufs_freed;
segundo	0:ac1725ba162c	206
segundo	0:ac1725ba162c	207	return pbufs_freed;
segundo	0:ac1725ba162c	208	}
segundo	0:ac1725ba162c	209
segundo	0:ac1725ba162c	210	#if IP_REASS_FREE_OLDEST
segundo	0:ac1725ba162c	211	/**
segundo	0:ac1725ba162c	212	* Free the oldest datagram to make room for enqueueing new fragments.
segundo	0:ac1725ba162c	213	* The datagram 'fraghdr' belongs to is not freed!
segundo	0:ac1725ba162c	214	*
segundo	0:ac1725ba162c	215	* @param fraghdr IP header of the current fragment
segundo	0:ac1725ba162c	216	* @param pbufs_needed number of pbufs needed to enqueue
segundo	0:ac1725ba162c	217	* (used for freeing other datagrams if not enough space)
segundo	0:ac1725ba162c	218	* @return the number of pbufs freed
segundo	0:ac1725ba162c	219	*/
segundo	0:ac1725ba162c	220	static int
segundo	0:ac1725ba162c	221	ip_reass_remove_oldest_datagram(struct ip_hdr *fraghdr, int pbufs_needed)
segundo	0:ac1725ba162c	222	{
segundo	0:ac1725ba162c	223	/* @todo Can't we simply remove the last datagram in the
segundo	0:ac1725ba162c	224	* linked list behind reassdatagrams?
segundo	0:ac1725ba162c	225	*/
segundo	0:ac1725ba162c	226	struct ip_reassdata r, oldest, *prev;
segundo	0:ac1725ba162c	227	int pbufs_freed = 0, pbufs_freed_current;
segundo	0:ac1725ba162c	228	int other_datagrams;
segundo	0:ac1725ba162c	229
segundo	0:ac1725ba162c	230	/* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs,
segundo	0:ac1725ba162c	231	* but don't free the datagram that 'fraghdr' belongs to! */
segundo	0:ac1725ba162c	232	do {
segundo	0:ac1725ba162c	233	oldest = NULL;
segundo	0:ac1725ba162c	234	prev = NULL;
segundo	0:ac1725ba162c	235	other_datagrams = 0;
segundo	0:ac1725ba162c	236	r = reassdatagrams;
segundo	0:ac1725ba162c	237	while (r != NULL) {
segundo	0:ac1725ba162c	238	if (!IP_ADDRESSES_AND_ID_MATCH(&r->iphdr, fraghdr)) {
segundo	0:ac1725ba162c	239	/* Not the same datagram as fraghdr */
segundo	0:ac1725ba162c	240	other_datagrams++;
segundo	0:ac1725ba162c	241	if (oldest == NULL) {
segundo	0:ac1725ba162c	242	oldest = r;
segundo	0:ac1725ba162c	243	} else if (r->timer <= oldest->timer) {
segundo	0:ac1725ba162c	244	/* older than the previous oldest */
segundo	0:ac1725ba162c	245	oldest = r;
segundo	0:ac1725ba162c	246	}
segundo	0:ac1725ba162c	247	}
segundo	0:ac1725ba162c	248	if (r->next != NULL) {
segundo	0:ac1725ba162c	249	prev = r;
segundo	0:ac1725ba162c	250	}
segundo	0:ac1725ba162c	251	r = r->next;
segundo	0:ac1725ba162c	252	}
segundo	0:ac1725ba162c	253	if (oldest != NULL) {
segundo	0:ac1725ba162c	254	pbufs_freed_current = ip_reass_free_complete_datagram(oldest, prev);
segundo	0:ac1725ba162c	255	pbufs_freed += pbufs_freed_current;
segundo	0:ac1725ba162c	256	}
segundo	0:ac1725ba162c	257	} while ((pbufs_freed < pbufs_needed) && (other_datagrams > 1));
segundo	0:ac1725ba162c	258	return pbufs_freed;
segundo	0:ac1725ba162c	259	}
segundo	0:ac1725ba162c	260	#endif /* IP_REASS_FREE_OLDEST */
segundo	0:ac1725ba162c	261
segundo	0:ac1725ba162c	262	/**
segundo	0:ac1725ba162c	263	* Enqueues a new fragment into the fragment queue
segundo	0:ac1725ba162c	264	* @param fraghdr points to the new fragments IP hdr
segundo	0:ac1725ba162c	265	* @param clen number of pbufs needed to enqueue (used for freeing other datagrams if not enough space)
segundo	0:ac1725ba162c	266	* @return A pointer to the queue location into which the fragment was enqueued
segundo	0:ac1725ba162c	267	*/
segundo	0:ac1725ba162c	268	static struct ip_reassdata*
segundo	0:ac1725ba162c	269	ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen)
segundo	0:ac1725ba162c	270	{
segundo	0:ac1725ba162c	271	struct ip_reassdata* ipr;
segundo	0:ac1725ba162c	272	/* No matching previous fragment found, allocate a new reassdata struct */
segundo	0:ac1725ba162c	273	ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
segundo	0:ac1725ba162c	274	if (ipr == NULL) {
segundo	0:ac1725ba162c	275	#if IP_REASS_FREE_OLDEST
segundo	0:ac1725ba162c	276	if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) {
segundo	0:ac1725ba162c	277	ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
segundo	0:ac1725ba162c	278	}
segundo	0:ac1725ba162c	279	if (ipr == NULL)
segundo	0:ac1725ba162c	280	#endif /* IP_REASS_FREE_OLDEST */
segundo	0:ac1725ba162c	281	{
segundo	0:ac1725ba162c	282	IPFRAG_STATS_INC(ip_frag.memerr);
segundo	0:ac1725ba162c	283	LWIP_DEBUGF(IP_REASS_DEBUG,("Failed to alloc reassdata struct\n"));
segundo	0:ac1725ba162c	284	return NULL;
segundo	0:ac1725ba162c	285	}
segundo	0:ac1725ba162c	286	}
segundo	0:ac1725ba162c	287	memset(ipr, 0, sizeof(struct ip_reassdata));
segundo	0:ac1725ba162c	288	ipr->timer = IP_REASS_MAXAGE;
segundo	0:ac1725ba162c	289
segundo	0:ac1725ba162c	290	/* enqueue the new structure to the front of the list */
segundo	0:ac1725ba162c	291	ipr->next = reassdatagrams;
segundo	0:ac1725ba162c	292	reassdatagrams = ipr;
segundo	0:ac1725ba162c	293	/* copy the ip header for later tests and input */
segundo	0:ac1725ba162c	294	/* @todo: no ip options supported? */
segundo	0:ac1725ba162c	295	SMEMCPY(&(ipr->iphdr), fraghdr, IP_HLEN);
segundo	0:ac1725ba162c	296	return ipr;
segundo	0:ac1725ba162c	297	}
segundo	0:ac1725ba162c	298
segundo	0:ac1725ba162c	299	/**
segundo	0:ac1725ba162c	300	* Dequeues a datagram from the datagram queue. Doesn't deallocate the pbufs.
segundo	0:ac1725ba162c	301	* @param ipr points to the queue entry to dequeue
segundo	0:ac1725ba162c	302	*/
segundo	0:ac1725ba162c	303	static void
segundo	0:ac1725ba162c	304	ip_reass_dequeue_datagram(struct ip_reassdata ipr, struct ip_reassdata prev)
segundo	0:ac1725ba162c	305	{
segundo	0:ac1725ba162c	306
segundo	0:ac1725ba162c	307	/* dequeue the reass struct */
segundo	0:ac1725ba162c	308	if (reassdatagrams == ipr) {
segundo	0:ac1725ba162c	309	/* it was the first in the list */
segundo	0:ac1725ba162c	310	reassdatagrams = ipr->next;
segundo	0:ac1725ba162c	311	} else {
segundo	0:ac1725ba162c	312	/* it wasn't the first, so it must have a valid 'prev' */
segundo	0:ac1725ba162c	313	LWIP_ASSERT("sanity check linked list", prev != NULL);
segundo	0:ac1725ba162c	314	prev->next = ipr->next;
segundo	0:ac1725ba162c	315	}
segundo	0:ac1725ba162c	316
segundo	0:ac1725ba162c	317	/* now we can free the ip_reass struct */
segundo	0:ac1725ba162c	318	memp_free(MEMP_REASSDATA, ipr);
segundo	0:ac1725ba162c	319	}
segundo	0:ac1725ba162c	320
segundo	0:ac1725ba162c	321	/**
segundo	0:ac1725ba162c	322	* Chain a new pbuf into the pbuf list that composes the datagram. The pbuf list
segundo	0:ac1725ba162c	323	* will grow over time as new pbufs are rx.
segundo	0:ac1725ba162c	324	* Also checks that the datagram passes basic continuity checks (if the last
segundo	0:ac1725ba162c	325	* fragment was received at least once).
segundo	0:ac1725ba162c	326	* @param root_p points to the 'root' pbuf for the current datagram being assembled.
segundo	0:ac1725ba162c	327	* @param new_p points to the pbuf for the current fragment
segundo	0:ac1725ba162c	328	* @return 0 if invalid, >0 otherwise
segundo	0:ac1725ba162c	329	*/
segundo	0:ac1725ba162c	330	static int
segundo	0:ac1725ba162c	331	ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata ipr, struct pbuf new_p)
segundo	0:ac1725ba162c	332	{
segundo	0:ac1725ba162c	333	struct ip_reass_helper iprh, iprh_tmp, *iprh_prev=NULL;
segundo	0:ac1725ba162c	334	struct pbuf *q;
segundo	0:ac1725ba162c	335	u16_t offset,len;
segundo	0:ac1725ba162c	336	struct ip_hdr *fraghdr;
segundo	0:ac1725ba162c	337	int valid = 1;
segundo	0:ac1725ba162c	338
segundo	0:ac1725ba162c	339	/* Extract length and fragment offset from current fragment */
segundo	0:ac1725ba162c	340	fraghdr = (struct ip_hdr*)new_p->payload;
segundo	0:ac1725ba162c	341	len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
segundo	0:ac1725ba162c	342	offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
segundo	0:ac1725ba162c	343
segundo	0:ac1725ba162c	344	/* overwrite the fragment's ip header from the pbuf with our helper struct,
segundo	0:ac1725ba162c	345	* and setup the embedded helper structure. */
segundo	0:ac1725ba162c	346	/* make sure the struct ip_reass_helper fits into the IP header */
segundo	0:ac1725ba162c	347	LWIP_ASSERT("sizeof(struct ip_reass_helper) <= IP_HLEN",
segundo	0:ac1725ba162c	348	sizeof(struct ip_reass_helper) <= IP_HLEN);
segundo	0:ac1725ba162c	349	iprh = (struct ip_reass_helper*)new_p->payload;
segundo	0:ac1725ba162c	350	iprh->next_pbuf = NULL;
segundo	0:ac1725ba162c	351	iprh->start = offset;
segundo	0:ac1725ba162c	352	iprh->end = offset + len;
segundo	0:ac1725ba162c	353
segundo	0:ac1725ba162c	354	/* Iterate through until we either get to the end of the list (append),
segundo	0:ac1725ba162c	355	* or we find on with a larger offset (insert). */
segundo	0:ac1725ba162c	356	for (q = ipr->p; q != NULL;) {
segundo	0:ac1725ba162c	357	iprh_tmp = (struct ip_reass_helper*)q->payload;
segundo	0:ac1725ba162c	358	if (iprh->start < iprh_tmp->start) {
segundo	0:ac1725ba162c	359	/* the new pbuf should be inserted before this */
segundo	0:ac1725ba162c	360	iprh->next_pbuf = q;
segundo	0:ac1725ba162c	361	if (iprh_prev != NULL) {
segundo	0:ac1725ba162c	362	/* not the fragment with the lowest offset */
segundo	0:ac1725ba162c	363	#if IP_REASS_CHECK_OVERLAP
segundo	0:ac1725ba162c	364	if ((iprh->start < iprh_prev->end) \|\| (iprh->end > iprh_tmp->start)) {
segundo	0:ac1725ba162c	365	/* fragment overlaps with previous or following, throw away */
segundo	0:ac1725ba162c	366	goto freepbuf;
segundo	0:ac1725ba162c	367	}
segundo	0:ac1725ba162c	368	#endif /* IP_REASS_CHECK_OVERLAP */
segundo	0:ac1725ba162c	369	iprh_prev->next_pbuf = new_p;
segundo	0:ac1725ba162c	370	} else {
segundo	0:ac1725ba162c	371	/* fragment with the lowest offset */
segundo	0:ac1725ba162c	372	ipr->p = new_p;
segundo	0:ac1725ba162c	373	}
segundo	0:ac1725ba162c	374	break;
segundo	0:ac1725ba162c	375	} else if(iprh->start == iprh_tmp->start) {
segundo	0:ac1725ba162c	376	/* received the same datagram twice: no need to keep the datagram */
segundo	0:ac1725ba162c	377	goto freepbuf;
segundo	0:ac1725ba162c	378	#if IP_REASS_CHECK_OVERLAP
segundo	0:ac1725ba162c	379	} else if(iprh->start < iprh_tmp->end) {
segundo	0:ac1725ba162c	380	/* overlap: no need to keep the new datagram */
segundo	0:ac1725ba162c	381	goto freepbuf;
segundo	0:ac1725ba162c	382	#endif /* IP_REASS_CHECK_OVERLAP */
segundo	0:ac1725ba162c	383	} else {
segundo	0:ac1725ba162c	384	/* Check if the fragments received so far have no wholes. */
segundo	0:ac1725ba162c	385	if (iprh_prev != NULL) {
segundo	0:ac1725ba162c	386	if (iprh_prev->end != iprh_tmp->start) {
segundo	0:ac1725ba162c	387	/* There is a fragment missing between the current
segundo	0:ac1725ba162c	388	* and the previous fragment */
segundo	0:ac1725ba162c	389	valid = 0;
segundo	0:ac1725ba162c	390	}
segundo	0:ac1725ba162c	391	}
segundo	0:ac1725ba162c	392	}
segundo	0:ac1725ba162c	393	q = iprh_tmp->next_pbuf;
segundo	0:ac1725ba162c	394	iprh_prev = iprh_tmp;
segundo	0:ac1725ba162c	395	}
segundo	0:ac1725ba162c	396
segundo	0:ac1725ba162c	397	/* If q is NULL, then we made it to the end of the list. Determine what to do now */
segundo	0:ac1725ba162c	398	if (q == NULL) {
segundo	0:ac1725ba162c	399	if (iprh_prev != NULL) {
segundo	0:ac1725ba162c	400	/* this is (for now), the fragment with the highest offset:
segundo	0:ac1725ba162c	401	* chain it to the last fragment */
segundo	0:ac1725ba162c	402	#if IP_REASS_CHECK_OVERLAP
segundo	0:ac1725ba162c	403	LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= iprh->start);
segundo	0:ac1725ba162c	404	#endif /* IP_REASS_CHECK_OVERLAP */
segundo	0:ac1725ba162c	405	iprh_prev->next_pbuf = new_p;
segundo	0:ac1725ba162c	406	if (iprh_prev->end != iprh->start) {
segundo	0:ac1725ba162c	407	valid = 0;
segundo	0:ac1725ba162c	408	}
segundo	0:ac1725ba162c	409	} else {
segundo	0:ac1725ba162c	410	#if IP_REASS_CHECK_OVERLAP
segundo	0:ac1725ba162c	411	LWIP_ASSERT("no previous fragment, this must be the first fragment!",
segundo	0:ac1725ba162c	412	ipr->p == NULL);
segundo	0:ac1725ba162c	413	#endif /* IP_REASS_CHECK_OVERLAP */
segundo	0:ac1725ba162c	414	/* this is the first fragment we ever received for this ip datagram */
segundo	0:ac1725ba162c	415	ipr->p = new_p;
segundo	0:ac1725ba162c	416	}
segundo	0:ac1725ba162c	417	}
segundo	0:ac1725ba162c	418
segundo	0:ac1725ba162c	419	/* At this point, the validation part begins: */
segundo	0:ac1725ba162c	420	/* If we already received the last fragment */
segundo	0:ac1725ba162c	421	if ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0) {
segundo	0:ac1725ba162c	422	/* and had no wholes so far */
segundo	0:ac1725ba162c	423	if (valid) {
segundo	0:ac1725ba162c	424	/* then check if the rest of the fragments is here */
segundo	0:ac1725ba162c	425	/* Check if the queue starts with the first datagram */
segundo	0:ac1725ba162c	426	if (((struct ip_reass_helper*)ipr->p->payload)->start != 0) {
segundo	0:ac1725ba162c	427	valid = 0;
segundo	0:ac1725ba162c	428	} else {
segundo	0:ac1725ba162c	429	/* and check that there are no wholes after this datagram */
segundo	0:ac1725ba162c	430	iprh_prev = iprh;
segundo	0:ac1725ba162c	431	q = iprh->next_pbuf;
segundo	0:ac1725ba162c	432	while (q != NULL) {
segundo	0:ac1725ba162c	433	iprh = (struct ip_reass_helper*)q->payload;
segundo	0:ac1725ba162c	434	if (iprh_prev->end != iprh->start) {
segundo	0:ac1725ba162c	435	valid = 0;
segundo	0:ac1725ba162c	436	break;
segundo	0:ac1725ba162c	437	}
segundo	0:ac1725ba162c	438	iprh_prev = iprh;
segundo	0:ac1725ba162c	439	q = iprh->next_pbuf;
segundo	0:ac1725ba162c	440	}
segundo	0:ac1725ba162c	441	/* if still valid, all fragments are received
segundo	0:ac1725ba162c	442	* (because to the MF==0 already arrived */
segundo	0:ac1725ba162c	443	if (valid) {
segundo	0:ac1725ba162c	444	LWIP_ASSERT("sanity check", ipr->p != NULL);
segundo	0:ac1725ba162c	445	LWIP_ASSERT("sanity check",
segundo	0:ac1725ba162c	446	((struct ip_reass_helper*)ipr->p->payload) != iprh);
segundo	0:ac1725ba162c	447	LWIP_ASSERT("validate_datagram:next_pbuf!=NULL",
segundo	0:ac1725ba162c	448	iprh->next_pbuf == NULL);
segundo	0:ac1725ba162c	449	LWIP_ASSERT("validate_datagram:datagram end!=datagram len",
segundo	0:ac1725ba162c	450	iprh->end == ipr->datagram_len);
segundo	0:ac1725ba162c	451	}
segundo	0:ac1725ba162c	452	}
segundo	0:ac1725ba162c	453	}
segundo	0:ac1725ba162c	454	/* If valid is 0 here, there are some fragments missing in the middle
segundo	0:ac1725ba162c	455	* (since MF == 0 has already arrived). Such datagrams simply time out if
segundo	0:ac1725ba162c	456	* no more fragments are received... */
segundo	0:ac1725ba162c	457	return valid;
segundo	0:ac1725ba162c	458	}
segundo	0:ac1725ba162c	459	/* If we come here, not all fragments were received, yet! */
segundo	0:ac1725ba162c	460	return 0; /* not yet valid! */
segundo	0:ac1725ba162c	461	#if IP_REASS_CHECK_OVERLAP
segundo	0:ac1725ba162c	462	freepbuf:
segundo	0:ac1725ba162c	463	ip_reass_pbufcount -= pbuf_clen(new_p);
segundo	0:ac1725ba162c	464	pbuf_free(new_p);
segundo	0:ac1725ba162c	465	return 0;
segundo	0:ac1725ba162c	466	#endif /* IP_REASS_CHECK_OVERLAP */
segundo	0:ac1725ba162c	467	}
segundo	0:ac1725ba162c	468
segundo	0:ac1725ba162c	469	/**
segundo	0:ac1725ba162c	470	* Reassembles incoming IP fragments into an IP datagram.
segundo	0:ac1725ba162c	471	*
segundo	0:ac1725ba162c	472	* @param p points to a pbuf chain of the fragment
segundo	0:ac1725ba162c	473	* @return NULL if reassembly is incomplete, ? otherwise
segundo	0:ac1725ba162c	474	*/
segundo	0:ac1725ba162c	475	struct pbuf *
segundo	0:ac1725ba162c	476	ip_reass(struct pbuf *p)
segundo	0:ac1725ba162c	477	{
segundo	0:ac1725ba162c	478	struct pbuf *r;
segundo	0:ac1725ba162c	479	struct ip_hdr *fraghdr;
segundo	0:ac1725ba162c	480	struct ip_reassdata *ipr;
segundo	0:ac1725ba162c	481	struct ip_reass_helper *iprh;
segundo	0:ac1725ba162c	482	u16_t offset, len;
segundo	0:ac1725ba162c	483	u8_t clen;
segundo	0:ac1725ba162c	484	struct ip_reassdata *ipr_prev = NULL;
segundo	0:ac1725ba162c	485
segundo	0:ac1725ba162c	486	IPFRAG_STATS_INC(ip_frag.recv);
segundo	0:ac1725ba162c	487	snmp_inc_ipreasmreqds();
segundo	0:ac1725ba162c	488
segundo	0:ac1725ba162c	489	fraghdr = (struct ip_hdr*)p->payload;
segundo	0:ac1725ba162c	490
segundo	0:ac1725ba162c	491	if ((IPH_HL(fraghdr) * 4) != IP_HLEN) {
segundo	0:ac1725ba162c	492	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: IP options currently not supported!\n"));
segundo	0:ac1725ba162c	493	IPFRAG_STATS_INC(ip_frag.err);
segundo	0:ac1725ba162c	494	goto nullreturn;
segundo	0:ac1725ba162c	495	}
segundo	0:ac1725ba162c	496
segundo	0:ac1725ba162c	497	offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
segundo	0:ac1725ba162c	498	len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
segundo	0:ac1725ba162c	499
segundo	0:ac1725ba162c	500	/* Check if we are allowed to enqueue more datagrams. */
segundo	0:ac1725ba162c	501	clen = pbuf_clen(p);
segundo	0:ac1725ba162c	502	if ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) {
segundo	0:ac1725ba162c	503	#if IP_REASS_FREE_OLDEST
segundo	0:ac1725ba162c	504	if (!ip_reass_remove_oldest_datagram(fraghdr, clen) \|\|
segundo	0:ac1725ba162c	505	((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS))
segundo	0:ac1725ba162c	506	#endif /* IP_REASS_FREE_OLDEST */
segundo	0:ac1725ba162c	507	{
segundo	0:ac1725ba162c	508	/* No datagram could be freed and still too many pbufs enqueued */
segundo	0:ac1725ba162c	509	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: Overflow condition: pbufct=%d, clen=%d, MAX=%d\n",
segundo	0:ac1725ba162c	510	ip_reass_pbufcount, clen, IP_REASS_MAX_PBUFS));
segundo	0:ac1725ba162c	511	IPFRAG_STATS_INC(ip_frag.memerr);
segundo	0:ac1725ba162c	512	/* @todo: send ICMP time exceeded here? */
segundo	0:ac1725ba162c	513	/* drop this pbuf */
segundo	0:ac1725ba162c	514	goto nullreturn;
segundo	0:ac1725ba162c	515	}
segundo	0:ac1725ba162c	516	}
segundo	0:ac1725ba162c	517
segundo	0:ac1725ba162c	518	/* Look for the datagram the fragment belongs to in the current datagram queue,
segundo	0:ac1725ba162c	519	* remembering the previous in the queue for later dequeueing. */
segundo	0:ac1725ba162c	520	for (ipr = reassdatagrams; ipr != NULL; ipr = ipr->next) {
segundo	0:ac1725ba162c	521	/* Check if the incoming fragment matches the one currently present
segundo	0:ac1725ba162c	522	in the reassembly buffer. If so, we proceed with copying the
segundo	0:ac1725ba162c	523	fragment into the buffer. */
segundo	0:ac1725ba162c	524	if (IP_ADDRESSES_AND_ID_MATCH(&ipr->iphdr, fraghdr)) {
segundo	0:ac1725ba162c	525	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass: matching previous fragment ID=%"X16_F"\n",
segundo	0:ac1725ba162c	526	ntohs(IPH_ID(fraghdr))));
segundo	0:ac1725ba162c	527	IPFRAG_STATS_INC(ip_frag.cachehit);
segundo	0:ac1725ba162c	528	break;
segundo	0:ac1725ba162c	529	}
segundo	0:ac1725ba162c	530	ipr_prev = ipr;
segundo	0:ac1725ba162c	531	}
segundo	0:ac1725ba162c	532
segundo	0:ac1725ba162c	533	if (ipr == NULL) {
segundo	0:ac1725ba162c	534	/* Enqueue a new datagram into the datagram queue */
segundo	0:ac1725ba162c	535	ipr = ip_reass_enqueue_new_datagram(fraghdr, clen);
segundo	0:ac1725ba162c	536	/* Bail if unable to enqueue */
segundo	0:ac1725ba162c	537	if(ipr == NULL) {
segundo	0:ac1725ba162c	538	goto nullreturn;
segundo	0:ac1725ba162c	539	}
segundo	0:ac1725ba162c	540	} else {
segundo	0:ac1725ba162c	541	if (((ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) == 0) &&
segundo	0:ac1725ba162c	542	((ntohs(IPH_OFFSET(&ipr->iphdr)) & IP_OFFMASK) != 0)) {
segundo	0:ac1725ba162c	543	/* ipr->iphdr is not the header from the first fragment, but fraghdr is
segundo	0:ac1725ba162c	544	* -> copy fraghdr into ipr->iphdr since we want to have the header
segundo	0:ac1725ba162c	545	* of the first fragment (for ICMP time exceeded and later, for copying
segundo	0:ac1725ba162c	546	* all options, if supported)*/
segundo	0:ac1725ba162c	547	SMEMCPY(&ipr->iphdr, fraghdr, IP_HLEN);
segundo	0:ac1725ba162c	548	}
segundo	0:ac1725ba162c	549	}
segundo	0:ac1725ba162c	550	/* Track the current number of pbufs current 'in-flight', in order to limit
segundo	0:ac1725ba162c	551	the number of fragments that may be enqueued at any one time */
segundo	0:ac1725ba162c	552	ip_reass_pbufcount += clen;
segundo	0:ac1725ba162c	553
segundo	0:ac1725ba162c	554	/* At this point, we have either created a new entry or pointing
segundo	0:ac1725ba162c	555	* to an existing one */
segundo	0:ac1725ba162c	556
segundo	0:ac1725ba162c	557	/* check for 'no more fragments', and update queue entry*/
segundo	0:ac1725ba162c	558	if ((IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0) {
segundo	0:ac1725ba162c	559	ipr->flags \|= IP_REASS_FLAG_LASTFRAG;
segundo	0:ac1725ba162c	560	ipr->datagram_len = offset + len;
segundo	0:ac1725ba162c	561	LWIP_DEBUGF(IP_REASS_DEBUG,
segundo	0:ac1725ba162c	562	("ip_reass: last fragment seen, total len %"S16_F"\n",
segundo	0:ac1725ba162c	563	ipr->datagram_len));
segundo	0:ac1725ba162c	564	}
segundo	0:ac1725ba162c	565	/* find the right place to insert this pbuf */
segundo	0:ac1725ba162c	566	/* @todo: trim pbufs if fragments are overlapping */
segundo	0:ac1725ba162c	567	if (ip_reass_chain_frag_into_datagram_and_validate(ipr, p)) {
segundo	0:ac1725ba162c	568	/* the totally last fragment (flag more fragments = 0) was received at least
segundo	0:ac1725ba162c	569	* once AND all fragments are received */
segundo	0:ac1725ba162c	570	ipr->datagram_len += IP_HLEN;
segundo	0:ac1725ba162c	571
segundo	0:ac1725ba162c	572	/* save the second pbuf before copying the header over the pointer */
segundo	0:ac1725ba162c	573	r = ((struct ip_reass_helper*)ipr->p->payload)->next_pbuf;
segundo	0:ac1725ba162c	574
segundo	0:ac1725ba162c	575	/* copy the original ip header back to the first pbuf */
segundo	0:ac1725ba162c	576	fraghdr = (struct ip_hdr*)(ipr->p->payload);
segundo	0:ac1725ba162c	577	SMEMCPY(fraghdr, &ipr->iphdr, IP_HLEN);
segundo	0:ac1725ba162c	578	IPH_LEN_SET(fraghdr, htons(ipr->datagram_len));
segundo	0:ac1725ba162c	579	IPH_OFFSET_SET(fraghdr, 0);
segundo	0:ac1725ba162c	580	IPH_CHKSUM_SET(fraghdr, 0);
segundo	0:ac1725ba162c	581	/* @todo: do we need to set calculate the correct checksum? */
segundo	0:ac1725ba162c	582	IPH_CHKSUM_SET(fraghdr, inet_chksum(fraghdr, IP_HLEN));
segundo	0:ac1725ba162c	583
segundo	0:ac1725ba162c	584	p = ipr->p;
segundo	0:ac1725ba162c	585
segundo	0:ac1725ba162c	586	/* chain together the pbufs contained within the reass_data list. */
segundo	0:ac1725ba162c	587	while(r != NULL) {
segundo	0:ac1725ba162c	588	iprh = (struct ip_reass_helper*)r->payload;
segundo	0:ac1725ba162c	589
segundo	0:ac1725ba162c	590	/* hide the ip header for every succeding fragment */
segundo	0:ac1725ba162c	591	pbuf_header(r, -IP_HLEN);
segundo	0:ac1725ba162c	592	pbuf_cat(p, r);
segundo	0:ac1725ba162c	593	r = iprh->next_pbuf;
segundo	0:ac1725ba162c	594	}
segundo	0:ac1725ba162c	595	/* release the sources allocate for the fragment queue entry */
segundo	0:ac1725ba162c	596	ip_reass_dequeue_datagram(ipr, ipr_prev);
segundo	0:ac1725ba162c	597
segundo	0:ac1725ba162c	598	/* and adjust the number of pbufs currently queued for reassembly. */
segundo	0:ac1725ba162c	599	ip_reass_pbufcount -= pbuf_clen(p);
segundo	0:ac1725ba162c	600
segundo	0:ac1725ba162c	601	/* Return the pbuf chain */
segundo	0:ac1725ba162c	602	return p;
segundo	0:ac1725ba162c	603	}
segundo	0:ac1725ba162c	604	/* the datagram is not (yet?) reassembled completely */
segundo	0:ac1725ba162c	605	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass_pbufcount: %d out\n", ip_reass_pbufcount));
segundo	0:ac1725ba162c	606	return NULL;
segundo	0:ac1725ba162c	607
segundo	0:ac1725ba162c	608	nullreturn:
segundo	0:ac1725ba162c	609	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: nullreturn\n"));
segundo	0:ac1725ba162c	610	IPFRAG_STATS_INC(ip_frag.drop);
segundo	0:ac1725ba162c	611	pbuf_free(p);
segundo	0:ac1725ba162c	612	return NULL;
segundo	0:ac1725ba162c	613	}
segundo	0:ac1725ba162c	614	#endif /* IP_REASSEMBLY */
segundo	0:ac1725ba162c	615
segundo	0:ac1725ba162c	616	#if IP_FRAG
segundo	0:ac1725ba162c	617	#if IP_FRAG_USES_STATIC_BUF
segundo	0:ac1725ba162c	618	static u8_t buf[LWIP_MEM_ALIGN_SIZE(IP_FRAG_MAX_MTU + MEM_ALIGNMENT - 1)];
segundo	0:ac1725ba162c	619	#else /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	620
segundo	0:ac1725ba162c	621	#if !LWIP_NETIF_TX_SINGLE_PBUF
segundo	0:ac1725ba162c	622	/** Allocate a new struct pbuf_custom_ref */
segundo	0:ac1725ba162c	623	static struct pbuf_custom_ref*
segundo	0:ac1725ba162c	624	ip_frag_alloc_pbuf_custom_ref(void)
segundo	0:ac1725ba162c	625	{
segundo	0:ac1725ba162c	626	return (struct pbuf_custom_ref*)memp_malloc(MEMP_FRAG_PBUF);
segundo	0:ac1725ba162c	627	}
segundo	0:ac1725ba162c	628
segundo	0:ac1725ba162c	629	/** Free a struct pbuf_custom_ref */
segundo	0:ac1725ba162c	630	static void
segundo	0:ac1725ba162c	631	ip_frag_free_pbuf_custom_ref(struct pbuf_custom_ref* p)
segundo	0:ac1725ba162c	632	{
segundo	0:ac1725ba162c	633	LWIP_ASSERT("p != NULL", p != NULL);
segundo	0:ac1725ba162c	634	memp_free(MEMP_FRAG_PBUF, p);
segundo	0:ac1725ba162c	635	}
segundo	0:ac1725ba162c	636
segundo	0:ac1725ba162c	637	/** Free-callback function to free a 'struct pbuf_custom_ref', called by
segundo	0:ac1725ba162c	638	* pbuf_free. */
segundo	0:ac1725ba162c	639	static void
segundo	0:ac1725ba162c	640	ipfrag_free_pbuf_custom(struct pbuf *p)
segundo	0:ac1725ba162c	641	{
segundo	0:ac1725ba162c	642	struct pbuf_custom_ref pcr = (struct pbuf_custom_ref)p;
segundo	0:ac1725ba162c	643	LWIP_ASSERT("pcr != NULL", pcr != NULL);
segundo	0:ac1725ba162c	644	LWIP_ASSERT("pcr == p", (void)pcr == (void)p);
segundo	0:ac1725ba162c	645	if (pcr->original != NULL) {
segundo	0:ac1725ba162c	646	pbuf_free(pcr->original);
segundo	0:ac1725ba162c	647	}
segundo	0:ac1725ba162c	648	ip_frag_free_pbuf_custom_ref(pcr);
segundo	0:ac1725ba162c	649	}
segundo	0:ac1725ba162c	650	#endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
segundo	0:ac1725ba162c	651	#endif /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	652
segundo	0:ac1725ba162c	653	/**
segundo	0:ac1725ba162c	654	* Fragment an IP datagram if too large for the netif.
segundo	0:ac1725ba162c	655	*
segundo	0:ac1725ba162c	656	* Chop the datagram in MTU sized chunks and send them in order
segundo	0:ac1725ba162c	657	* by using a fixed size static memory buffer (PBUF_REF) or
segundo	0:ac1725ba162c	658	* point PBUF_REFs into p (depending on IP_FRAG_USES_STATIC_BUF).
segundo	0:ac1725ba162c	659	*
segundo	0:ac1725ba162c	660	* @param p ip packet to send
segundo	0:ac1725ba162c	661	* @param netif the netif on which to send
segundo	0:ac1725ba162c	662	* @param dest destination ip address to which to send
segundo	0:ac1725ba162c	663	*
segundo	0:ac1725ba162c	664	* @return ERR_OK if sent successfully, err_t otherwise
segundo	0:ac1725ba162c	665	*/
segundo	0:ac1725ba162c	666	err_t
segundo	0:ac1725ba162c	667	ip_frag(struct pbuf p, struct netif netif, ip_addr_t *dest)
segundo	0:ac1725ba162c	668	{
segundo	0:ac1725ba162c	669	struct pbuf *rambuf;
segundo	0:ac1725ba162c	670	#if IP_FRAG_USES_STATIC_BUF
segundo	0:ac1725ba162c	671	struct pbuf *header;
segundo	0:ac1725ba162c	672	#else
segundo	0:ac1725ba162c	673	#if !LWIP_NETIF_TX_SINGLE_PBUF
segundo	0:ac1725ba162c	674	struct pbuf *newpbuf;
segundo	0:ac1725ba162c	675	#endif
segundo	0:ac1725ba162c	676	struct ip_hdr *original_iphdr;
segundo	0:ac1725ba162c	677	#endif
segundo	0:ac1725ba162c	678	struct ip_hdr *iphdr;
segundo	0:ac1725ba162c	679	u16_t nfb;
segundo	0:ac1725ba162c	680	u16_t left, cop;
segundo	0:ac1725ba162c	681	u16_t mtu = netif->mtu;
segundo	0:ac1725ba162c	682	u16_t ofo, omf;
segundo	0:ac1725ba162c	683	u16_t last;
segundo	0:ac1725ba162c	684	u16_t poff = IP_HLEN;
segundo	0:ac1725ba162c	685	u16_t tmp;
segundo	0:ac1725ba162c	686	#if !IP_FRAG_USES_STATIC_BUF && !LWIP_NETIF_TX_SINGLE_PBUF
segundo	0:ac1725ba162c	687	u16_t newpbuflen = 0;
segundo	0:ac1725ba162c	688	u16_t left_to_copy;
segundo	0:ac1725ba162c	689	#endif
segundo	0:ac1725ba162c	690
segundo	0:ac1725ba162c	691	/* Get a RAM based MTU sized pbuf */
segundo	0:ac1725ba162c	692	#if IP_FRAG_USES_STATIC_BUF
segundo	0:ac1725ba162c	693	/* When using a static buffer, we use a PBUF_REF, which we will
segundo	0:ac1725ba162c	694	* use to reference the packet (without link header).
segundo	0:ac1725ba162c	695	* Layer and length is irrelevant.
segundo	0:ac1725ba162c	696	*/
segundo	0:ac1725ba162c	697	rambuf = pbuf_alloc(PBUF_LINK, 0, PBUF_REF);
segundo	0:ac1725ba162c	698	if (rambuf == NULL) {
segundo	0:ac1725ba162c	699	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc(PBUF_LINK, 0, PBUF_REF) failed\n"));
segundo	0:ac1725ba162c	700	return ERR_MEM;
segundo	0:ac1725ba162c	701	}
segundo	0:ac1725ba162c	702	rambuf->tot_len = rambuf->len = mtu;
segundo	0:ac1725ba162c	703	rambuf->payload = LWIP_MEM_ALIGN((void *)buf);
segundo	0:ac1725ba162c	704
segundo	0:ac1725ba162c	705	/* Copy the IP header in it */
segundo	0:ac1725ba162c	706	iphdr = (struct ip_hdr *)rambuf->payload;
segundo	0:ac1725ba162c	707	SMEMCPY(iphdr, p->payload, IP_HLEN);
segundo	0:ac1725ba162c	708	#else /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	709	original_iphdr = (struct ip_hdr *)p->payload;
segundo	0:ac1725ba162c	710	iphdr = original_iphdr;
segundo	0:ac1725ba162c	711	#endif /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	712
segundo	0:ac1725ba162c	713	/* Save original offset */
segundo	0:ac1725ba162c	714	tmp = ntohs(IPH_OFFSET(iphdr));
segundo	0:ac1725ba162c	715	ofo = tmp & IP_OFFMASK;
segundo	0:ac1725ba162c	716	omf = tmp & IP_MF;
segundo	0:ac1725ba162c	717
segundo	0:ac1725ba162c	718	left = p->tot_len - IP_HLEN;
segundo	0:ac1725ba162c	719
segundo	0:ac1725ba162c	720	nfb = (mtu - IP_HLEN) / 8;
segundo	0:ac1725ba162c	721
segundo	0:ac1725ba162c	722	while (left) {
segundo	0:ac1725ba162c	723	last = (left <= mtu - IP_HLEN);
segundo	0:ac1725ba162c	724
segundo	0:ac1725ba162c	725	/* Set new offset and MF flag */
segundo	0:ac1725ba162c	726	tmp = omf \| (IP_OFFMASK & (ofo));
segundo	0:ac1725ba162c	727	if (!last) {
segundo	0:ac1725ba162c	728	tmp = tmp \| IP_MF;
segundo	0:ac1725ba162c	729	}
segundo	0:ac1725ba162c	730
segundo	0:ac1725ba162c	731	/* Fill this fragment */
segundo	0:ac1725ba162c	732	cop = last ? left : nfb * 8;
segundo	0:ac1725ba162c	733
segundo	0:ac1725ba162c	734	#if IP_FRAG_USES_STATIC_BUF
segundo	0:ac1725ba162c	735	poff += pbuf_copy_partial(p, (u8_t*)iphdr + IP_HLEN, cop, poff);
segundo	0:ac1725ba162c	736	#else /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	737	#if LWIP_NETIF_TX_SINGLE_PBUF
segundo	0:ac1725ba162c	738	rambuf = pbuf_alloc(PBUF_IP, cop, PBUF_RAM);
segundo	0:ac1725ba162c	739	if (rambuf == NULL) {
segundo	0:ac1725ba162c	740	return ERR_MEM;
segundo	0:ac1725ba162c	741	}
segundo	0:ac1725ba162c	742	LWIP_ASSERT("this needs a pbuf in one piece!",
segundo	0:ac1725ba162c	743	(rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
segundo	0:ac1725ba162c	744	poff += pbuf_copy_partial(p, rambuf->payload, cop, poff);
segundo	0:ac1725ba162c	745	/* make room for the IP header */
segundo	0:ac1725ba162c	746	if(pbuf_header(rambuf, IP_HLEN)) {
segundo	0:ac1725ba162c	747	pbuf_free(rambuf);
segundo	0:ac1725ba162c	748	return ERR_MEM;
segundo	0:ac1725ba162c	749	}
segundo	0:ac1725ba162c	750	/* fill in the IP header */
segundo	0:ac1725ba162c	751	SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
segundo	0:ac1725ba162c	752	iphdr = rambuf->payload;
segundo	0:ac1725ba162c	753	#else /* LWIP_NETIF_TX_SINGLE_PBUF */
segundo	0:ac1725ba162c	754	/* When not using a static buffer, create a chain of pbufs.
segundo	0:ac1725ba162c	755	* The first will be a PBUF_RAM holding the link and IP header.
segundo	0:ac1725ba162c	756	* The rest will be PBUF_REFs mirroring the pbuf chain to be fragged,
segundo	0:ac1725ba162c	757	* but limited to the size of an mtu.
segundo	0:ac1725ba162c	758	*/
segundo	0:ac1725ba162c	759	rambuf = pbuf_alloc(PBUF_LINK, IP_HLEN, PBUF_RAM);
segundo	0:ac1725ba162c	760	if (rambuf == NULL) {
segundo	0:ac1725ba162c	761	return ERR_MEM;
segundo	0:ac1725ba162c	762	}
segundo	0:ac1725ba162c	763	LWIP_ASSERT("this needs a pbuf in one piece!",
segundo	0:ac1725ba162c	764	(p->len >= (IP_HLEN)));
segundo	0:ac1725ba162c	765	SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
segundo	0:ac1725ba162c	766	iphdr = (struct ip_hdr *)rambuf->payload;
segundo	0:ac1725ba162c	767
segundo	0:ac1725ba162c	768	/* Can just adjust p directly for needed offset. */
segundo	0:ac1725ba162c	769	p->payload = (u8_t *)p->payload + poff;
segundo	0:ac1725ba162c	770	p->len -= poff;
segundo	0:ac1725ba162c	771
segundo	0:ac1725ba162c	772	left_to_copy = cop;
segundo	0:ac1725ba162c	773	while (left_to_copy) {
segundo	0:ac1725ba162c	774	struct pbuf_custom_ref *pcr;
segundo	0:ac1725ba162c	775	newpbuflen = (left_to_copy < p->len) ? left_to_copy : p->len;
segundo	0:ac1725ba162c	776	/* Is this pbuf already empty? */
segundo	0:ac1725ba162c	777	if (!newpbuflen) {
segundo	0:ac1725ba162c	778	p = p->next;
segundo	0:ac1725ba162c	779	continue;
segundo	0:ac1725ba162c	780	}
segundo	0:ac1725ba162c	781	pcr = ip_frag_alloc_pbuf_custom_ref();
segundo	0:ac1725ba162c	782	if (pcr == NULL) {
segundo	0:ac1725ba162c	783	pbuf_free(rambuf);
segundo	0:ac1725ba162c	784	return ERR_MEM;
segundo	0:ac1725ba162c	785	}
segundo	0:ac1725ba162c	786	/* Mirror this pbuf, although we might not need all of it. */
segundo	0:ac1725ba162c	787	newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc, p->payload, newpbuflen);
segundo	0:ac1725ba162c	788	if (newpbuf == NULL) {
segundo	0:ac1725ba162c	789	ip_frag_free_pbuf_custom_ref(pcr);
segundo	0:ac1725ba162c	790	pbuf_free(rambuf);
segundo	0:ac1725ba162c	791	return ERR_MEM;
segundo	0:ac1725ba162c	792	}
segundo	0:ac1725ba162c	793	pbuf_ref(p);
segundo	0:ac1725ba162c	794	pcr->original = p;
segundo	0:ac1725ba162c	795	pcr->pc.custom_free_function = ipfrag_free_pbuf_custom;
segundo	0:ac1725ba162c	796
segundo	0:ac1725ba162c	797	/* Add it to end of rambuf's chain, but using pbuf_cat, not pbuf_chain
segundo	0:ac1725ba162c	798	* so that it is removed when pbuf_dechain is later called on rambuf.
segundo	0:ac1725ba162c	799	*/
segundo	0:ac1725ba162c	800	pbuf_cat(rambuf, newpbuf);
segundo	0:ac1725ba162c	801	left_to_copy -= newpbuflen;
segundo	0:ac1725ba162c	802	if (left_to_copy) {
segundo	0:ac1725ba162c	803	p = p->next;
segundo	0:ac1725ba162c	804	}
segundo	0:ac1725ba162c	805	}
segundo	0:ac1725ba162c	806	poff = newpbuflen;
segundo	0:ac1725ba162c	807	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
segundo	0:ac1725ba162c	808	#endif /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	809
segundo	0:ac1725ba162c	810	/* Correct header */
segundo	0:ac1725ba162c	811	IPH_OFFSET_SET(iphdr, htons(tmp));
segundo	0:ac1725ba162c	812	IPH_LEN_SET(iphdr, htons(cop + IP_HLEN));
segundo	0:ac1725ba162c	813	IPH_CHKSUM_SET(iphdr, 0);
segundo	0:ac1725ba162c	814	IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
segundo	0:ac1725ba162c	815
segundo	0:ac1725ba162c	816	#if IP_FRAG_USES_STATIC_BUF
segundo	0:ac1725ba162c	817	if (last) {
segundo	0:ac1725ba162c	818	pbuf_realloc(rambuf, left + IP_HLEN);
segundo	0:ac1725ba162c	819	}
segundo	0:ac1725ba162c	820
segundo	0:ac1725ba162c	821	/* This part is ugly: we alloc a RAM based pbuf for
segundo	0:ac1725ba162c	822	* the link level header for each chunk and then
segundo	0:ac1725ba162c	823	* free it.A PBUF_ROM style pbuf for which pbuf_header
segundo	0:ac1725ba162c	824	* worked would make things simpler.
segundo	0:ac1725ba162c	825	*/
segundo	0:ac1725ba162c	826	header = pbuf_alloc(PBUF_LINK, 0, PBUF_RAM);
segundo	0:ac1725ba162c	827	if (header != NULL) {
segundo	0:ac1725ba162c	828	pbuf_chain(header, rambuf);
segundo	0:ac1725ba162c	829	netif->output(netif, header, dest);
segundo	0:ac1725ba162c	830	IPFRAG_STATS_INC(ip_frag.xmit);
segundo	0:ac1725ba162c	831	snmp_inc_ipfragcreates();
segundo	0:ac1725ba162c	832	pbuf_free(header);
segundo	0:ac1725ba162c	833	} else {
segundo	0:ac1725ba162c	834	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc() for header failed\n"));
segundo	0:ac1725ba162c	835	pbuf_free(rambuf);
segundo	0:ac1725ba162c	836	return ERR_MEM;
segundo	0:ac1725ba162c	837	}
segundo	0:ac1725ba162c	838	#else /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	839	/* No need for separate header pbuf - we allowed room for it in rambuf
segundo	0:ac1725ba162c	840	* when allocated.
segundo	0:ac1725ba162c	841	*/
segundo	0:ac1725ba162c	842	netif->output(netif, rambuf, dest);
segundo	0:ac1725ba162c	843	IPFRAG_STATS_INC(ip_frag.xmit);
segundo	0:ac1725ba162c	844
segundo	0:ac1725ba162c	845	/* Unfortunately we can't reuse rambuf - the hardware may still be
segundo	0:ac1725ba162c	846	* using the buffer. Instead we free it (and the ensuing chain) and
segundo	0:ac1725ba162c	847	* recreate it next time round the loop. If we're lucky the hardware
segundo	0:ac1725ba162c	848	* will have already sent the packet, the free will really free, and
segundo	0:ac1725ba162c	849	* there will be zero memory penalty.
segundo	0:ac1725ba162c	850	*/
segundo	0:ac1725ba162c	851
segundo	0:ac1725ba162c	852	pbuf_free(rambuf);
segundo	0:ac1725ba162c	853	#endif /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	854	left -= cop;
segundo	0:ac1725ba162c	855	ofo += nfb;
segundo	0:ac1725ba162c	856	}
segundo	0:ac1725ba162c	857	#if IP_FRAG_USES_STATIC_BUF
segundo	0:ac1725ba162c	858	pbuf_free(rambuf);
segundo	0:ac1725ba162c	859	#endif /* IP_FRAG_USES_STATIC_BUF */
segundo	0:ac1725ba162c	860	snmp_inc_ipfragoks();
segundo	0:ac1725ba162c	861	return ERR_OK;
segundo	0:ac1725ba162c	862	}
segundo	0:ac1725ba162c	863	#endif /* IP_FRAG */

Repository toolbox

Export to desktop IDE

Repository details

Type:	Library
Created:	09 Nov 2010
Imports:	3034
Forks:	1
Commits:	8
Dependents:	42
Dependencies:	0
Followers:	27

lwip/core/ipv4/ip_frag.c@0:ac1725ba162c, 2010-11-09 (annotated)

Who changed what in which revision?

Repository toolbox

Repository details

Important Information for this Arm website

Access Warning