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lwip/core/ipv4/ip_frag.c@0:281d6ff68967, 2010-11-19 (annotated)

Committer:: hexley
Date:: Fri Nov 19 01:54:45 2010 +0000
Revision:: 0:281d6ff68967

Who changed what in which revision?

User	Revision	Line number	New contents of line
hexley	0:281d6ff68967	1	/**
hexley	0:281d6ff68967	2	* @file
hexley	0:281d6ff68967	3	* This is the IPv4 packet segmentation and reassembly implementation.
hexley	0:281d6ff68967	4	*
hexley	0:281d6ff68967	5	*/
hexley	0:281d6ff68967	6
hexley	0:281d6ff68967	7	/*
hexley	0:281d6ff68967	8	* Copyright (c) 2001-2004 Swedish Institute of Computer Science.
hexley	0:281d6ff68967	9	* All rights reserved.
hexley	0:281d6ff68967	10	*
hexley	0:281d6ff68967	11	* Redistribution and use in source and binary forms, with or without modification,
hexley	0:281d6ff68967	12	* are permitted provided that the following conditions are met:
hexley	0:281d6ff68967	13	*
hexley	0:281d6ff68967	14	* 1. Redistributions of source code must retain the above copyright notice,
hexley	0:281d6ff68967	15	* this list of conditions and the following disclaimer.
hexley	0:281d6ff68967	16	* 2. Redistributions in binary form must reproduce the above copyright notice,
hexley	0:281d6ff68967	17	* this list of conditions and the following disclaimer in the documentation
hexley	0:281d6ff68967	18	* and/or other materials provided with the distribution.
hexley	0:281d6ff68967	19	* 3. The name of the author may not be used to endorse or promote products
hexley	0:281d6ff68967	20	* derived from this software without specific prior written permission.
hexley	0:281d6ff68967	21	*
hexley	0:281d6ff68967	22	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
hexley	0:281d6ff68967	23	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
hexley	0:281d6ff68967	24	* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
hexley	0:281d6ff68967	25	* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
hexley	0:281d6ff68967	26	* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
hexley	0:281d6ff68967	27	* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
hexley	0:281d6ff68967	28	* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
hexley	0:281d6ff68967	29	* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
hexley	0:281d6ff68967	30	* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
hexley	0:281d6ff68967	31	* OF SUCH DAMAGE.
hexley	0:281d6ff68967	32	*
hexley	0:281d6ff68967	33	* This file is part of the lwIP TCP/IP stack.
hexley	0:281d6ff68967	34	*
hexley	0:281d6ff68967	35	* Author: Jani Monoses <jani@iv.ro>
hexley	0:281d6ff68967	36	* Simon Goldschmidt
hexley	0:281d6ff68967	37	* original reassembly code by Adam Dunkels <adam@sics.se>
hexley	0:281d6ff68967	38	*
hexley	0:281d6ff68967	39	*/
hexley	0:281d6ff68967	40
hexley	0:281d6ff68967	41	#include "lwip/opt.h"
hexley	0:281d6ff68967	42	#include "lwip/ip_frag.h"
hexley	0:281d6ff68967	43	#include "lwip/def.h"
hexley	0:281d6ff68967	44	#include "lwip/inet_chksum.h"
hexley	0:281d6ff68967	45	#include "lwip/netif.h"
hexley	0:281d6ff68967	46	#include "lwip/snmp.h"
hexley	0:281d6ff68967	47	#include "lwip/stats.h"
hexley	0:281d6ff68967	48	#include "lwip/icmp.h"
hexley	0:281d6ff68967	49
hexley	0:281d6ff68967	50	#include <string.h>
hexley	0:281d6ff68967	51
hexley	0:281d6ff68967	52	#if IP_REASSEMBLY
hexley	0:281d6ff68967	53	/**
hexley	0:281d6ff68967	54	* The IP reassembly code currently has the following limitations:
hexley	0:281d6ff68967	55	* - IP header options are not supported
hexley	0:281d6ff68967	56	* - fragments must not overlap (e.g. due to different routes),
hexley	0:281d6ff68967	57	* currently, overlapping or duplicate fragments are thrown away
hexley	0:281d6ff68967	58	* if IP_REASS_CHECK_OVERLAP=1 (the default)!
hexley	0:281d6ff68967	59	*
hexley	0:281d6ff68967	60	* @todo: work with IP header options
hexley	0:281d6ff68967	61	*/
hexley	0:281d6ff68967	62
hexley	0:281d6ff68967	63	/** Setting this to 0, you can turn off checking the fragments for overlapping
hexley	0:281d6ff68967	64	* regions. The code gets a little smaller. Only use this if you know that
hexley	0:281d6ff68967	65	* overlapping won't occur on your network! */
hexley	0:281d6ff68967	66	#ifndef IP_REASS_CHECK_OVERLAP
hexley	0:281d6ff68967	67	#define IP_REASS_CHECK_OVERLAP 1
hexley	0:281d6ff68967	68	#endif /* IP_REASS_CHECK_OVERLAP */
hexley	0:281d6ff68967	69
hexley	0:281d6ff68967	70	/** Set to 0 to prevent freeing the oldest datagram when the reassembly buffer is
hexley	0:281d6ff68967	71	* full (IP_REASS_MAX_PBUFS pbufs are enqueued). The code gets a little smaller.
hexley	0:281d6ff68967	72	* Datagrams will be freed by timeout only. Especially useful when MEMP_NUM_REASSDATA
hexley	0:281d6ff68967	73	* is set to 1, so one datagram can be reassembled at a time, only. */
hexley	0:281d6ff68967	74	#ifndef IP_REASS_FREE_OLDEST
hexley	0:281d6ff68967	75	#define IP_REASS_FREE_OLDEST 1
hexley	0:281d6ff68967	76	#endif /* IP_REASS_FREE_OLDEST */
hexley	0:281d6ff68967	77
hexley	0:281d6ff68967	78	#define IP_REASS_FLAG_LASTFRAG 0x01
hexley	0:281d6ff68967	79
hexley	0:281d6ff68967	80	/** This is a helper struct which holds the starting
hexley	0:281d6ff68967	81	* offset and the ending offset of this fragment to
hexley	0:281d6ff68967	82	* easily chain the fragments.
hexley	0:281d6ff68967	83	* It has the same packing requirements as the IP header, since it replaces
hexley	0:281d6ff68967	84	* the IP header in memory in incoming fragments (after copying it) to keep
hexley	0:281d6ff68967	85	* track of the various fragments. (-> If the IP header doesn't need packing,
hexley	0:281d6ff68967	86	* this struct doesn't need packing, too.)
hexley	0:281d6ff68967	87	*/
hexley	0:281d6ff68967	88	#ifdef PACK_STRUCT_USE_INCLUDES
hexley	0:281d6ff68967	89	# include "arch/bpstruct.h"
hexley	0:281d6ff68967	90	#endif
hexley	0:281d6ff68967	91	PACK_STRUCT_BEGIN
hexley	0:281d6ff68967	92	struct ip_reass_helper {
hexley	0:281d6ff68967	93	PACK_STRUCT_FIELD(struct pbuf *next_pbuf);
hexley	0:281d6ff68967	94	PACK_STRUCT_FIELD(u16_t start);
hexley	0:281d6ff68967	95	PACK_STRUCT_FIELD(u16_t end);
hexley	0:281d6ff68967	96	} PACK_STRUCT_STRUCT;
hexley	0:281d6ff68967	97	PACK_STRUCT_END
hexley	0:281d6ff68967	98	#ifdef PACK_STRUCT_USE_INCLUDES
hexley	0:281d6ff68967	99	# include "arch/epstruct.h"
hexley	0:281d6ff68967	100	#endif
hexley	0:281d6ff68967	101
hexley	0:281d6ff68967	102	#define IP_ADDRESSES_AND_ID_MATCH(iphdrA, iphdrB) \
hexley	0:281d6ff68967	103	(ip_addr_cmp(&(iphdrA)->src, &(iphdrB)->src) && \
hexley	0:281d6ff68967	104	ip_addr_cmp(&(iphdrA)->dest, &(iphdrB)->dest) && \
hexley	0:281d6ff68967	105	IPH_ID(iphdrA) == IPH_ID(iphdrB)) ? 1 : 0
hexley	0:281d6ff68967	106
hexley	0:281d6ff68967	107	/* global variables */
hexley	0:281d6ff68967	108	static struct ip_reassdata *reassdatagrams;
hexley	0:281d6ff68967	109	static u16_t ip_reass_pbufcount;
hexley	0:281d6ff68967	110
hexley	0:281d6ff68967	111	/* function prototypes */
hexley	0:281d6ff68967	112	static void ip_reass_dequeue_datagram(struct ip_reassdata ipr, struct ip_reassdata prev);
hexley	0:281d6ff68967	113	static int ip_reass_free_complete_datagram(struct ip_reassdata ipr, struct ip_reassdata prev);
hexley	0:281d6ff68967	114
hexley	0:281d6ff68967	115	/**
hexley	0:281d6ff68967	116	* Reassembly timer base function
hexley	0:281d6ff68967	117	* for both NO_SYS == 0 and 1 (!).
hexley	0:281d6ff68967	118	*
hexley	0:281d6ff68967	119	* Should be called every 1000 msec (defined by IP_TMR_INTERVAL).
hexley	0:281d6ff68967	120	*/
hexley	0:281d6ff68967	121	void
hexley	0:281d6ff68967	122	ip_reass_tmr(void)
hexley	0:281d6ff68967	123	{
hexley	0:281d6ff68967	124	struct ip_reassdata r, prev = NULL;
hexley	0:281d6ff68967	125
hexley	0:281d6ff68967	126	r = reassdatagrams;
hexley	0:281d6ff68967	127	while (r != NULL) {
hexley	0:281d6ff68967	128	/* Decrement the timer. Once it reaches 0,
hexley	0:281d6ff68967	129	* clean up the incomplete fragment assembly */
hexley	0:281d6ff68967	130	if (r->timer > 0) {
hexley	0:281d6ff68967	131	r->timer--;
hexley	0:281d6ff68967	132	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer dec %"U16_F"\n",(u16_t)r->timer));
hexley	0:281d6ff68967	133	prev = r;
hexley	0:281d6ff68967	134	r = r->next;
hexley	0:281d6ff68967	135	} else {
hexley	0:281d6ff68967	136	/* reassembly timed out */
hexley	0:281d6ff68967	137	struct ip_reassdata *tmp;
hexley	0:281d6ff68967	138	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass_tmr: timer timed out\n"));
hexley	0:281d6ff68967	139	tmp = r;
hexley	0:281d6ff68967	140	/* get the next pointer before freeing */
hexley	0:281d6ff68967	141	r = r->next;
hexley	0:281d6ff68967	142	/* free the helper struct and all enqueued pbufs */
hexley	0:281d6ff68967	143	ip_reass_free_complete_datagram(tmp, prev);
hexley	0:281d6ff68967	144	}
hexley	0:281d6ff68967	145	}
hexley	0:281d6ff68967	146	}
hexley	0:281d6ff68967	147
hexley	0:281d6ff68967	148	/**
hexley	0:281d6ff68967	149	* Free a datagram (struct ip_reassdata) and all its pbufs.
hexley	0:281d6ff68967	150	* Updates the total count of enqueued pbufs (ip_reass_pbufcount),
hexley	0:281d6ff68967	151	* SNMP counters and sends an ICMP time exceeded packet.
hexley	0:281d6ff68967	152	*
hexley	0:281d6ff68967	153	* @param ipr datagram to free
hexley	0:281d6ff68967	154	* @param prev the previous datagram in the linked list
hexley	0:281d6ff68967	155	* @return the number of pbufs freed
hexley	0:281d6ff68967	156	*/
hexley	0:281d6ff68967	157	static int
hexley	0:281d6ff68967	158	ip_reass_free_complete_datagram(struct ip_reassdata ipr, struct ip_reassdata prev)
hexley	0:281d6ff68967	159	{
hexley	0:281d6ff68967	160	u16_t pbufs_freed = 0;
hexley	0:281d6ff68967	161	u8_t clen;
hexley	0:281d6ff68967	162	struct pbuf *p;
hexley	0:281d6ff68967	163	struct ip_reass_helper *iprh;
hexley	0:281d6ff68967	164
hexley	0:281d6ff68967	165	LWIP_ASSERT("prev != ipr", prev != ipr);
hexley	0:281d6ff68967	166	if (prev != NULL) {
hexley	0:281d6ff68967	167	LWIP_ASSERT("prev->next == ipr", prev->next == ipr);
hexley	0:281d6ff68967	168	}
hexley	0:281d6ff68967	169
hexley	0:281d6ff68967	170	snmp_inc_ipreasmfails();
hexley	0:281d6ff68967	171	#if LWIP_ICMP
hexley	0:281d6ff68967	172	iprh = (struct ip_reass_helper *)ipr->p->payload;
hexley	0:281d6ff68967	173	if (iprh->start == 0) {
hexley	0:281d6ff68967	174	/* The first fragment was received, send ICMP time exceeded. */
hexley	0:281d6ff68967	175	/* First, de-queue the first pbuf from r->p. */
hexley	0:281d6ff68967	176	p = ipr->p;
hexley	0:281d6ff68967	177	ipr->p = iprh->next_pbuf;
hexley	0:281d6ff68967	178	/* Then, copy the original header into it. */
hexley	0:281d6ff68967	179	SMEMCPY(p->payload, &ipr->iphdr, IP_HLEN);
hexley	0:281d6ff68967	180	icmp_time_exceeded(p, ICMP_TE_FRAG);
hexley	0:281d6ff68967	181	clen = pbuf_clen(p);
hexley	0:281d6ff68967	182	LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
hexley	0:281d6ff68967	183	pbufs_freed += clen;
hexley	0:281d6ff68967	184	pbuf_free(p);
hexley	0:281d6ff68967	185	}
hexley	0:281d6ff68967	186	#endif /* LWIP_ICMP */
hexley	0:281d6ff68967	187
hexley	0:281d6ff68967	188	/* First, free all received pbufs. The individual pbufs need to be released
hexley	0:281d6ff68967	189	separately as they have not yet been chained */
hexley	0:281d6ff68967	190	p = ipr->p;
hexley	0:281d6ff68967	191	while (p != NULL) {
hexley	0:281d6ff68967	192	struct pbuf *pcur;
hexley	0:281d6ff68967	193	iprh = (struct ip_reass_helper *)p->payload;
hexley	0:281d6ff68967	194	pcur = p;
hexley	0:281d6ff68967	195	/* get the next pointer before freeing */
hexley	0:281d6ff68967	196	p = iprh->next_pbuf;
hexley	0:281d6ff68967	197	clen = pbuf_clen(pcur);
hexley	0:281d6ff68967	198	LWIP_ASSERT("pbufs_freed + clen <= 0xffff", pbufs_freed + clen <= 0xffff);
hexley	0:281d6ff68967	199	pbufs_freed += clen;
hexley	0:281d6ff68967	200	pbuf_free(pcur);
hexley	0:281d6ff68967	201	}
hexley	0:281d6ff68967	202	/* Then, unchain the struct ip_reassdata from the list and free it. */
hexley	0:281d6ff68967	203	ip_reass_dequeue_datagram(ipr, prev);
hexley	0:281d6ff68967	204	LWIP_ASSERT("ip_reass_pbufcount >= clen", ip_reass_pbufcount >= pbufs_freed);
hexley	0:281d6ff68967	205	ip_reass_pbufcount -= pbufs_freed;
hexley	0:281d6ff68967	206
hexley	0:281d6ff68967	207	return pbufs_freed;
hexley	0:281d6ff68967	208	}
hexley	0:281d6ff68967	209
hexley	0:281d6ff68967	210	#if IP_REASS_FREE_OLDEST
hexley	0:281d6ff68967	211	/**
hexley	0:281d6ff68967	212	* Free the oldest datagram to make room for enqueueing new fragments.
hexley	0:281d6ff68967	213	* The datagram 'fraghdr' belongs to is not freed!
hexley	0:281d6ff68967	214	*
hexley	0:281d6ff68967	215	* @param fraghdr IP header of the current fragment
hexley	0:281d6ff68967	216	* @param pbufs_needed number of pbufs needed to enqueue
hexley	0:281d6ff68967	217	* (used for freeing other datagrams if not enough space)
hexley	0:281d6ff68967	218	* @return the number of pbufs freed
hexley	0:281d6ff68967	219	*/
hexley	0:281d6ff68967	220	static int
hexley	0:281d6ff68967	221	ip_reass_remove_oldest_datagram(struct ip_hdr *fraghdr, int pbufs_needed)
hexley	0:281d6ff68967	222	{
hexley	0:281d6ff68967	223	/* @todo Can't we simply remove the last datagram in the
hexley	0:281d6ff68967	224	* linked list behind reassdatagrams?
hexley	0:281d6ff68967	225	*/
hexley	0:281d6ff68967	226	struct ip_reassdata r, oldest, *prev;
hexley	0:281d6ff68967	227	int pbufs_freed = 0, pbufs_freed_current;
hexley	0:281d6ff68967	228	int other_datagrams;
hexley	0:281d6ff68967	229
hexley	0:281d6ff68967	230	/* Free datagrams until being allowed to enqueue 'pbufs_needed' pbufs,
hexley	0:281d6ff68967	231	* but don't free the datagram that 'fraghdr' belongs to! */
hexley	0:281d6ff68967	232	do {
hexley	0:281d6ff68967	233	oldest = NULL;
hexley	0:281d6ff68967	234	prev = NULL;
hexley	0:281d6ff68967	235	other_datagrams = 0;
hexley	0:281d6ff68967	236	r = reassdatagrams;
hexley	0:281d6ff68967	237	while (r != NULL) {
hexley	0:281d6ff68967	238	if (!IP_ADDRESSES_AND_ID_MATCH(&r->iphdr, fraghdr)) {
hexley	0:281d6ff68967	239	/* Not the same datagram as fraghdr */
hexley	0:281d6ff68967	240	other_datagrams++;
hexley	0:281d6ff68967	241	if (oldest == NULL) {
hexley	0:281d6ff68967	242	oldest = r;
hexley	0:281d6ff68967	243	} else if (r->timer <= oldest->timer) {
hexley	0:281d6ff68967	244	/* older than the previous oldest */
hexley	0:281d6ff68967	245	oldest = r;
hexley	0:281d6ff68967	246	}
hexley	0:281d6ff68967	247	}
hexley	0:281d6ff68967	248	if (r->next != NULL) {
hexley	0:281d6ff68967	249	prev = r;
hexley	0:281d6ff68967	250	}
hexley	0:281d6ff68967	251	r = r->next;
hexley	0:281d6ff68967	252	}
hexley	0:281d6ff68967	253	if (oldest != NULL) {
hexley	0:281d6ff68967	254	pbufs_freed_current = ip_reass_free_complete_datagram(oldest, prev);
hexley	0:281d6ff68967	255	pbufs_freed += pbufs_freed_current;
hexley	0:281d6ff68967	256	}
hexley	0:281d6ff68967	257	} while ((pbufs_freed < pbufs_needed) && (other_datagrams > 1));
hexley	0:281d6ff68967	258	return pbufs_freed;
hexley	0:281d6ff68967	259	}
hexley	0:281d6ff68967	260	#endif /* IP_REASS_FREE_OLDEST */
hexley	0:281d6ff68967	261
hexley	0:281d6ff68967	262	/**
hexley	0:281d6ff68967	263	* Enqueues a new fragment into the fragment queue
hexley	0:281d6ff68967	264	* @param fraghdr points to the new fragments IP hdr
hexley	0:281d6ff68967	265	* @param clen number of pbufs needed to enqueue (used for freeing other datagrams if not enough space)
hexley	0:281d6ff68967	266	* @return A pointer to the queue location into which the fragment was enqueued
hexley	0:281d6ff68967	267	*/
hexley	0:281d6ff68967	268	static struct ip_reassdata*
hexley	0:281d6ff68967	269	ip_reass_enqueue_new_datagram(struct ip_hdr *fraghdr, int clen)
hexley	0:281d6ff68967	270	{
hexley	0:281d6ff68967	271	struct ip_reassdata* ipr;
hexley	0:281d6ff68967	272	/* No matching previous fragment found, allocate a new reassdata struct */
hexley	0:281d6ff68967	273	ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
hexley	0:281d6ff68967	274	if (ipr == NULL) {
hexley	0:281d6ff68967	275	#if IP_REASS_FREE_OLDEST
hexley	0:281d6ff68967	276	if (ip_reass_remove_oldest_datagram(fraghdr, clen) >= clen) {
hexley	0:281d6ff68967	277	ipr = (struct ip_reassdata *)memp_malloc(MEMP_REASSDATA);
hexley	0:281d6ff68967	278	}
hexley	0:281d6ff68967	279	if (ipr == NULL)
hexley	0:281d6ff68967	280	#endif /* IP_REASS_FREE_OLDEST */
hexley	0:281d6ff68967	281	{
hexley	0:281d6ff68967	282	IPFRAG_STATS_INC(ip_frag.memerr);
hexley	0:281d6ff68967	283	LWIP_DEBUGF(IP_REASS_DEBUG,("Failed to alloc reassdata struct\n"));
hexley	0:281d6ff68967	284	return NULL;
hexley	0:281d6ff68967	285	}
hexley	0:281d6ff68967	286	}
hexley	0:281d6ff68967	287	memset(ipr, 0, sizeof(struct ip_reassdata));
hexley	0:281d6ff68967	288	ipr->timer = IP_REASS_MAXAGE;
hexley	0:281d6ff68967	289
hexley	0:281d6ff68967	290	/* enqueue the new structure to the front of the list */
hexley	0:281d6ff68967	291	ipr->next = reassdatagrams;
hexley	0:281d6ff68967	292	reassdatagrams = ipr;
hexley	0:281d6ff68967	293	/* copy the ip header for later tests and input */
hexley	0:281d6ff68967	294	/* @todo: no ip options supported? */
hexley	0:281d6ff68967	295	SMEMCPY(&(ipr->iphdr), fraghdr, IP_HLEN);
hexley	0:281d6ff68967	296	return ipr;
hexley	0:281d6ff68967	297	}
hexley	0:281d6ff68967	298
hexley	0:281d6ff68967	299	/**
hexley	0:281d6ff68967	300	* Dequeues a datagram from the datagram queue. Doesn't deallocate the pbufs.
hexley	0:281d6ff68967	301	* @param ipr points to the queue entry to dequeue
hexley	0:281d6ff68967	302	*/
hexley	0:281d6ff68967	303	static void
hexley	0:281d6ff68967	304	ip_reass_dequeue_datagram(struct ip_reassdata ipr, struct ip_reassdata prev)
hexley	0:281d6ff68967	305	{
hexley	0:281d6ff68967	306
hexley	0:281d6ff68967	307	/* dequeue the reass struct */
hexley	0:281d6ff68967	308	if (reassdatagrams == ipr) {
hexley	0:281d6ff68967	309	/* it was the first in the list */
hexley	0:281d6ff68967	310	reassdatagrams = ipr->next;
hexley	0:281d6ff68967	311	} else {
hexley	0:281d6ff68967	312	/* it wasn't the first, so it must have a valid 'prev' */
hexley	0:281d6ff68967	313	LWIP_ASSERT("sanity check linked list", prev != NULL);
hexley	0:281d6ff68967	314	prev->next = ipr->next;
hexley	0:281d6ff68967	315	}
hexley	0:281d6ff68967	316
hexley	0:281d6ff68967	317	/* now we can free the ip_reass struct */
hexley	0:281d6ff68967	318	memp_free(MEMP_REASSDATA, ipr);
hexley	0:281d6ff68967	319	}
hexley	0:281d6ff68967	320
hexley	0:281d6ff68967	321	/**
hexley	0:281d6ff68967	322	* Chain a new pbuf into the pbuf list that composes the datagram. The pbuf list
hexley	0:281d6ff68967	323	* will grow over time as new pbufs are rx.
hexley	0:281d6ff68967	324	* Also checks that the datagram passes basic continuity checks (if the last
hexley	0:281d6ff68967	325	* fragment was received at least once).
hexley	0:281d6ff68967	326	* @param root_p points to the 'root' pbuf for the current datagram being assembled.
hexley	0:281d6ff68967	327	* @param new_p points to the pbuf for the current fragment
hexley	0:281d6ff68967	328	* @return 0 if invalid, >0 otherwise
hexley	0:281d6ff68967	329	*/
hexley	0:281d6ff68967	330	static int
hexley	0:281d6ff68967	331	ip_reass_chain_frag_into_datagram_and_validate(struct ip_reassdata ipr, struct pbuf new_p)
hexley	0:281d6ff68967	332	{
hexley	0:281d6ff68967	333	struct ip_reass_helper iprh, iprh_tmp, *iprh_prev=NULL;
hexley	0:281d6ff68967	334	struct pbuf *q;
hexley	0:281d6ff68967	335	u16_t offset,len;
hexley	0:281d6ff68967	336	struct ip_hdr *fraghdr;
hexley	0:281d6ff68967	337	int valid = 1;
hexley	0:281d6ff68967	338
hexley	0:281d6ff68967	339	/* Extract length and fragment offset from current fragment */
hexley	0:281d6ff68967	340	fraghdr = (struct ip_hdr*)new_p->payload;
hexley	0:281d6ff68967	341	len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
hexley	0:281d6ff68967	342	offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
hexley	0:281d6ff68967	343
hexley	0:281d6ff68967	344	/* overwrite the fragment's ip header from the pbuf with our helper struct,
hexley	0:281d6ff68967	345	* and setup the embedded helper structure. */
hexley	0:281d6ff68967	346	/* make sure the struct ip_reass_helper fits into the IP header */
hexley	0:281d6ff68967	347	LWIP_ASSERT("sizeof(struct ip_reass_helper) <= IP_HLEN",
hexley	0:281d6ff68967	348	sizeof(struct ip_reass_helper) <= IP_HLEN);
hexley	0:281d6ff68967	349	iprh = (struct ip_reass_helper*)new_p->payload;
hexley	0:281d6ff68967	350	iprh->next_pbuf = NULL;
hexley	0:281d6ff68967	351	iprh->start = offset;
hexley	0:281d6ff68967	352	iprh->end = offset + len;
hexley	0:281d6ff68967	353
hexley	0:281d6ff68967	354	/* Iterate through until we either get to the end of the list (append),
hexley	0:281d6ff68967	355	* or we find on with a larger offset (insert). */
hexley	0:281d6ff68967	356	for (q = ipr->p; q != NULL;) {
hexley	0:281d6ff68967	357	iprh_tmp = (struct ip_reass_helper*)q->payload;
hexley	0:281d6ff68967	358	if (iprh->start < iprh_tmp->start) {
hexley	0:281d6ff68967	359	/* the new pbuf should be inserted before this */
hexley	0:281d6ff68967	360	iprh->next_pbuf = q;
hexley	0:281d6ff68967	361	if (iprh_prev != NULL) {
hexley	0:281d6ff68967	362	/* not the fragment with the lowest offset */
hexley	0:281d6ff68967	363	#if IP_REASS_CHECK_OVERLAP
hexley	0:281d6ff68967	364	if ((iprh->start < iprh_prev->end) \|\| (iprh->end > iprh_tmp->start)) {
hexley	0:281d6ff68967	365	/* fragment overlaps with previous or following, throw away */
hexley	0:281d6ff68967	366	goto freepbuf;
hexley	0:281d6ff68967	367	}
hexley	0:281d6ff68967	368	#endif /* IP_REASS_CHECK_OVERLAP */
hexley	0:281d6ff68967	369	iprh_prev->next_pbuf = new_p;
hexley	0:281d6ff68967	370	} else {
hexley	0:281d6ff68967	371	/* fragment with the lowest offset */
hexley	0:281d6ff68967	372	ipr->p = new_p;
hexley	0:281d6ff68967	373	}
hexley	0:281d6ff68967	374	break;
hexley	0:281d6ff68967	375	} else if(iprh->start == iprh_tmp->start) {
hexley	0:281d6ff68967	376	/* received the same datagram twice: no need to keep the datagram */
hexley	0:281d6ff68967	377	goto freepbuf;
hexley	0:281d6ff68967	378	#if IP_REASS_CHECK_OVERLAP
hexley	0:281d6ff68967	379	} else if(iprh->start < iprh_tmp->end) {
hexley	0:281d6ff68967	380	/* overlap: no need to keep the new datagram */
hexley	0:281d6ff68967	381	goto freepbuf;
hexley	0:281d6ff68967	382	#endif /* IP_REASS_CHECK_OVERLAP */
hexley	0:281d6ff68967	383	} else {
hexley	0:281d6ff68967	384	/* Check if the fragments received so far have no wholes. */
hexley	0:281d6ff68967	385	if (iprh_prev != NULL) {
hexley	0:281d6ff68967	386	if (iprh_prev->end != iprh_tmp->start) {
hexley	0:281d6ff68967	387	/* There is a fragment missing between the current
hexley	0:281d6ff68967	388	* and the previous fragment */
hexley	0:281d6ff68967	389	valid = 0;
hexley	0:281d6ff68967	390	}
hexley	0:281d6ff68967	391	}
hexley	0:281d6ff68967	392	}
hexley	0:281d6ff68967	393	q = iprh_tmp->next_pbuf;
hexley	0:281d6ff68967	394	iprh_prev = iprh_tmp;
hexley	0:281d6ff68967	395	}
hexley	0:281d6ff68967	396
hexley	0:281d6ff68967	397	/* If q is NULL, then we made it to the end of the list. Determine what to do now */
hexley	0:281d6ff68967	398	if (q == NULL) {
hexley	0:281d6ff68967	399	if (iprh_prev != NULL) {
hexley	0:281d6ff68967	400	/* this is (for now), the fragment with the highest offset:
hexley	0:281d6ff68967	401	* chain it to the last fragment */
hexley	0:281d6ff68967	402	#if IP_REASS_CHECK_OVERLAP
hexley	0:281d6ff68967	403	LWIP_ASSERT("check fragments don't overlap", iprh_prev->end <= iprh->start);
hexley	0:281d6ff68967	404	#endif /* IP_REASS_CHECK_OVERLAP */
hexley	0:281d6ff68967	405	iprh_prev->next_pbuf = new_p;
hexley	0:281d6ff68967	406	if (iprh_prev->end != iprh->start) {
hexley	0:281d6ff68967	407	valid = 0;
hexley	0:281d6ff68967	408	}
hexley	0:281d6ff68967	409	} else {
hexley	0:281d6ff68967	410	#if IP_REASS_CHECK_OVERLAP
hexley	0:281d6ff68967	411	LWIP_ASSERT("no previous fragment, this must be the first fragment!",
hexley	0:281d6ff68967	412	ipr->p == NULL);
hexley	0:281d6ff68967	413	#endif /* IP_REASS_CHECK_OVERLAP */
hexley	0:281d6ff68967	414	/* this is the first fragment we ever received for this ip datagram */
hexley	0:281d6ff68967	415	ipr->p = new_p;
hexley	0:281d6ff68967	416	}
hexley	0:281d6ff68967	417	}
hexley	0:281d6ff68967	418
hexley	0:281d6ff68967	419	/* At this point, the validation part begins: */
hexley	0:281d6ff68967	420	/* If we already received the last fragment */
hexley	0:281d6ff68967	421	if ((ipr->flags & IP_REASS_FLAG_LASTFRAG) != 0) {
hexley	0:281d6ff68967	422	/* and had no wholes so far */
hexley	0:281d6ff68967	423	if (valid) {
hexley	0:281d6ff68967	424	/* then check if the rest of the fragments is here */
hexley	0:281d6ff68967	425	/* Check if the queue starts with the first datagram */
hexley	0:281d6ff68967	426	if (((struct ip_reass_helper*)ipr->p->payload)->start != 0) {
hexley	0:281d6ff68967	427	valid = 0;
hexley	0:281d6ff68967	428	} else {
hexley	0:281d6ff68967	429	/* and check that there are no wholes after this datagram */
hexley	0:281d6ff68967	430	iprh_prev = iprh;
hexley	0:281d6ff68967	431	q = iprh->next_pbuf;
hexley	0:281d6ff68967	432	while (q != NULL) {
hexley	0:281d6ff68967	433	iprh = (struct ip_reass_helper*)q->payload;
hexley	0:281d6ff68967	434	if (iprh_prev->end != iprh->start) {
hexley	0:281d6ff68967	435	valid = 0;
hexley	0:281d6ff68967	436	break;
hexley	0:281d6ff68967	437	}
hexley	0:281d6ff68967	438	iprh_prev = iprh;
hexley	0:281d6ff68967	439	q = iprh->next_pbuf;
hexley	0:281d6ff68967	440	}
hexley	0:281d6ff68967	441	/* if still valid, all fragments are received
hexley	0:281d6ff68967	442	* (because to the MF==0 already arrived */
hexley	0:281d6ff68967	443	if (valid) {
hexley	0:281d6ff68967	444	LWIP_ASSERT("sanity check", ipr->p != NULL);
hexley	0:281d6ff68967	445	LWIP_ASSERT("sanity check",
hexley	0:281d6ff68967	446	((struct ip_reass_helper*)ipr->p->payload) != iprh);
hexley	0:281d6ff68967	447	LWIP_ASSERT("validate_datagram:next_pbuf!=NULL",
hexley	0:281d6ff68967	448	iprh->next_pbuf == NULL);
hexley	0:281d6ff68967	449	LWIP_ASSERT("validate_datagram:datagram end!=datagram len",
hexley	0:281d6ff68967	450	iprh->end == ipr->datagram_len);
hexley	0:281d6ff68967	451	}
hexley	0:281d6ff68967	452	}
hexley	0:281d6ff68967	453	}
hexley	0:281d6ff68967	454	/* If valid is 0 here, there are some fragments missing in the middle
hexley	0:281d6ff68967	455	* (since MF == 0 has already arrived). Such datagrams simply time out if
hexley	0:281d6ff68967	456	* no more fragments are received... */
hexley	0:281d6ff68967	457	return valid;
hexley	0:281d6ff68967	458	}
hexley	0:281d6ff68967	459	/* If we come here, not all fragments were received, yet! */
hexley	0:281d6ff68967	460	return 0; /* not yet valid! */
hexley	0:281d6ff68967	461	#if IP_REASS_CHECK_OVERLAP
hexley	0:281d6ff68967	462	freepbuf:
hexley	0:281d6ff68967	463	ip_reass_pbufcount -= pbuf_clen(new_p);
hexley	0:281d6ff68967	464	pbuf_free(new_p);
hexley	0:281d6ff68967	465	return 0;
hexley	0:281d6ff68967	466	#endif /* IP_REASS_CHECK_OVERLAP */
hexley	0:281d6ff68967	467	}
hexley	0:281d6ff68967	468
hexley	0:281d6ff68967	469	/**
hexley	0:281d6ff68967	470	* Reassembles incoming IP fragments into an IP datagram.
hexley	0:281d6ff68967	471	*
hexley	0:281d6ff68967	472	* @param p points to a pbuf chain of the fragment
hexley	0:281d6ff68967	473	* @return NULL if reassembly is incomplete, ? otherwise
hexley	0:281d6ff68967	474	*/
hexley	0:281d6ff68967	475	struct pbuf *
hexley	0:281d6ff68967	476	ip_reass(struct pbuf *p)
hexley	0:281d6ff68967	477	{
hexley	0:281d6ff68967	478	struct pbuf *r;
hexley	0:281d6ff68967	479	struct ip_hdr *fraghdr;
hexley	0:281d6ff68967	480	struct ip_reassdata *ipr;
hexley	0:281d6ff68967	481	struct ip_reass_helper *iprh;
hexley	0:281d6ff68967	482	u16_t offset, len;
hexley	0:281d6ff68967	483	u8_t clen;
hexley	0:281d6ff68967	484	struct ip_reassdata *ipr_prev = NULL;
hexley	0:281d6ff68967	485
hexley	0:281d6ff68967	486	IPFRAG_STATS_INC(ip_frag.recv);
hexley	0:281d6ff68967	487	snmp_inc_ipreasmreqds();
hexley	0:281d6ff68967	488
hexley	0:281d6ff68967	489	fraghdr = (struct ip_hdr*)p->payload;
hexley	0:281d6ff68967	490
hexley	0:281d6ff68967	491	if ((IPH_HL(fraghdr) * 4) != IP_HLEN) {
hexley	0:281d6ff68967	492	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: IP options currently not supported!\n"));
hexley	0:281d6ff68967	493	IPFRAG_STATS_INC(ip_frag.err);
hexley	0:281d6ff68967	494	goto nullreturn;
hexley	0:281d6ff68967	495	}
hexley	0:281d6ff68967	496
hexley	0:281d6ff68967	497	offset = (ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) * 8;
hexley	0:281d6ff68967	498	len = ntohs(IPH_LEN(fraghdr)) - IPH_HL(fraghdr) * 4;
hexley	0:281d6ff68967	499
hexley	0:281d6ff68967	500	/* Check if we are allowed to enqueue more datagrams. */
hexley	0:281d6ff68967	501	clen = pbuf_clen(p);
hexley	0:281d6ff68967	502	if ((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS) {
hexley	0:281d6ff68967	503	#if IP_REASS_FREE_OLDEST
hexley	0:281d6ff68967	504	if (!ip_reass_remove_oldest_datagram(fraghdr, clen) \|\|
hexley	0:281d6ff68967	505	((ip_reass_pbufcount + clen) > IP_REASS_MAX_PBUFS))
hexley	0:281d6ff68967	506	#endif /* IP_REASS_FREE_OLDEST */
hexley	0:281d6ff68967	507	{
hexley	0:281d6ff68967	508	/* No datagram could be freed and still too many pbufs enqueued */
hexley	0:281d6ff68967	509	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: Overflow condition: pbufct=%d, clen=%d, MAX=%d\n",
hexley	0:281d6ff68967	510	ip_reass_pbufcount, clen, IP_REASS_MAX_PBUFS));
hexley	0:281d6ff68967	511	IPFRAG_STATS_INC(ip_frag.memerr);
hexley	0:281d6ff68967	512	/* @todo: send ICMP time exceeded here? */
hexley	0:281d6ff68967	513	/* drop this pbuf */
hexley	0:281d6ff68967	514	goto nullreturn;
hexley	0:281d6ff68967	515	}
hexley	0:281d6ff68967	516	}
hexley	0:281d6ff68967	517
hexley	0:281d6ff68967	518	/* Look for the datagram the fragment belongs to in the current datagram queue,
hexley	0:281d6ff68967	519	* remembering the previous in the queue for later dequeueing. */
hexley	0:281d6ff68967	520	for (ipr = reassdatagrams; ipr != NULL; ipr = ipr->next) {
hexley	0:281d6ff68967	521	/* Check if the incoming fragment matches the one currently present
hexley	0:281d6ff68967	522	in the reassembly buffer. If so, we proceed with copying the
hexley	0:281d6ff68967	523	fragment into the buffer. */
hexley	0:281d6ff68967	524	if (IP_ADDRESSES_AND_ID_MATCH(&ipr->iphdr, fraghdr)) {
hexley	0:281d6ff68967	525	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_reass: matching previous fragment ID=%"X16_F"\n",
hexley	0:281d6ff68967	526	ntohs(IPH_ID(fraghdr))));
hexley	0:281d6ff68967	527	IPFRAG_STATS_INC(ip_frag.cachehit);
hexley	0:281d6ff68967	528	break;
hexley	0:281d6ff68967	529	}
hexley	0:281d6ff68967	530	ipr_prev = ipr;
hexley	0:281d6ff68967	531	}
hexley	0:281d6ff68967	532
hexley	0:281d6ff68967	533	if (ipr == NULL) {
hexley	0:281d6ff68967	534	/* Enqueue a new datagram into the datagram queue */
hexley	0:281d6ff68967	535	ipr = ip_reass_enqueue_new_datagram(fraghdr, clen);
hexley	0:281d6ff68967	536	/* Bail if unable to enqueue */
hexley	0:281d6ff68967	537	if(ipr == NULL) {
hexley	0:281d6ff68967	538	goto nullreturn;
hexley	0:281d6ff68967	539	}
hexley	0:281d6ff68967	540	} else {
hexley	0:281d6ff68967	541	if (((ntohs(IPH_OFFSET(fraghdr)) & IP_OFFMASK) == 0) &&
hexley	0:281d6ff68967	542	((ntohs(IPH_OFFSET(&ipr->iphdr)) & IP_OFFMASK) != 0)) {
hexley	0:281d6ff68967	543	/* ipr->iphdr is not the header from the first fragment, but fraghdr is
hexley	0:281d6ff68967	544	* -> copy fraghdr into ipr->iphdr since we want to have the header
hexley	0:281d6ff68967	545	* of the first fragment (for ICMP time exceeded and later, for copying
hexley	0:281d6ff68967	546	* all options, if supported)*/
hexley	0:281d6ff68967	547	SMEMCPY(&ipr->iphdr, fraghdr, IP_HLEN);
hexley	0:281d6ff68967	548	}
hexley	0:281d6ff68967	549	}
hexley	0:281d6ff68967	550	/* Track the current number of pbufs current 'in-flight', in order to limit
hexley	0:281d6ff68967	551	the number of fragments that may be enqueued at any one time */
hexley	0:281d6ff68967	552	ip_reass_pbufcount += clen;
hexley	0:281d6ff68967	553
hexley	0:281d6ff68967	554	/* At this point, we have either created a new entry or pointing
hexley	0:281d6ff68967	555	* to an existing one */
hexley	0:281d6ff68967	556
hexley	0:281d6ff68967	557	/* check for 'no more fragments', and update queue entry*/
hexley	0:281d6ff68967	558	if ((IPH_OFFSET(fraghdr) & PP_NTOHS(IP_MF)) == 0) {
hexley	0:281d6ff68967	559	ipr->flags \|= IP_REASS_FLAG_LASTFRAG;
hexley	0:281d6ff68967	560	ipr->datagram_len = offset + len;
hexley	0:281d6ff68967	561	LWIP_DEBUGF(IP_REASS_DEBUG,
hexley	0:281d6ff68967	562	("ip_reass: last fragment seen, total len %"S16_F"\n",
hexley	0:281d6ff68967	563	ipr->datagram_len));
hexley	0:281d6ff68967	564	}
hexley	0:281d6ff68967	565	/* find the right place to insert this pbuf */
hexley	0:281d6ff68967	566	/* @todo: trim pbufs if fragments are overlapping */
hexley	0:281d6ff68967	567	if (ip_reass_chain_frag_into_datagram_and_validate(ipr, p)) {
hexley	0:281d6ff68967	568	/* the totally last fragment (flag more fragments = 0) was received at least
hexley	0:281d6ff68967	569	* once AND all fragments are received */
hexley	0:281d6ff68967	570	ipr->datagram_len += IP_HLEN;
hexley	0:281d6ff68967	571
hexley	0:281d6ff68967	572	/* save the second pbuf before copying the header over the pointer */
hexley	0:281d6ff68967	573	r = ((struct ip_reass_helper*)ipr->p->payload)->next_pbuf;
hexley	0:281d6ff68967	574
hexley	0:281d6ff68967	575	/* copy the original ip header back to the first pbuf */
hexley	0:281d6ff68967	576	fraghdr = (struct ip_hdr*)(ipr->p->payload);
hexley	0:281d6ff68967	577	SMEMCPY(fraghdr, &ipr->iphdr, IP_HLEN);
hexley	0:281d6ff68967	578	IPH_LEN_SET(fraghdr, htons(ipr->datagram_len));
hexley	0:281d6ff68967	579	IPH_OFFSET_SET(fraghdr, 0);
hexley	0:281d6ff68967	580	IPH_CHKSUM_SET(fraghdr, 0);
hexley	0:281d6ff68967	581	/* @todo: do we need to set calculate the correct checksum? */
hexley	0:281d6ff68967	582	IPH_CHKSUM_SET(fraghdr, inet_chksum(fraghdr, IP_HLEN));
hexley	0:281d6ff68967	583
hexley	0:281d6ff68967	584	p = ipr->p;
hexley	0:281d6ff68967	585
hexley	0:281d6ff68967	586	/* chain together the pbufs contained within the reass_data list. */
hexley	0:281d6ff68967	587	while(r != NULL) {
hexley	0:281d6ff68967	588	iprh = (struct ip_reass_helper*)r->payload;
hexley	0:281d6ff68967	589
hexley	0:281d6ff68967	590	/* hide the ip header for every succeding fragment */
hexley	0:281d6ff68967	591	pbuf_header(r, -IP_HLEN);
hexley	0:281d6ff68967	592	pbuf_cat(p, r);
hexley	0:281d6ff68967	593	r = iprh->next_pbuf;
hexley	0:281d6ff68967	594	}
hexley	0:281d6ff68967	595	/* release the sources allocate for the fragment queue entry */
hexley	0:281d6ff68967	596	ip_reass_dequeue_datagram(ipr, ipr_prev);
hexley	0:281d6ff68967	597
hexley	0:281d6ff68967	598	/* and adjust the number of pbufs currently queued for reassembly. */
hexley	0:281d6ff68967	599	ip_reass_pbufcount -= pbuf_clen(p);
hexley	0:281d6ff68967	600
hexley	0:281d6ff68967	601	/* Return the pbuf chain */
hexley	0:281d6ff68967	602	return p;
hexley	0:281d6ff68967	603	}
hexley	0:281d6ff68967	604	/* the datagram is not (yet?) reassembled completely */
hexley	0:281d6ff68967	605	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass_pbufcount: %d out\n", ip_reass_pbufcount));
hexley	0:281d6ff68967	606	return NULL;
hexley	0:281d6ff68967	607
hexley	0:281d6ff68967	608	nullreturn:
hexley	0:281d6ff68967	609	LWIP_DEBUGF(IP_REASS_DEBUG,("ip_reass: nullreturn\n"));
hexley	0:281d6ff68967	610	IPFRAG_STATS_INC(ip_frag.drop);
hexley	0:281d6ff68967	611	pbuf_free(p);
hexley	0:281d6ff68967	612	return NULL;
hexley	0:281d6ff68967	613	}
hexley	0:281d6ff68967	614	#endif /* IP_REASSEMBLY */
hexley	0:281d6ff68967	615
hexley	0:281d6ff68967	616	#if IP_FRAG
hexley	0:281d6ff68967	617	#if IP_FRAG_USES_STATIC_BUF
hexley	0:281d6ff68967	618	static u8_t buf[LWIP_MEM_ALIGN_SIZE(IP_FRAG_MAX_MTU + MEM_ALIGNMENT - 1)];
hexley	0:281d6ff68967	619	#else /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	620
hexley	0:281d6ff68967	621	#if !LWIP_NETIF_TX_SINGLE_PBUF
hexley	0:281d6ff68967	622	/** Allocate a new struct pbuf_custom_ref */
hexley	0:281d6ff68967	623	static struct pbuf_custom_ref*
hexley	0:281d6ff68967	624	ip_frag_alloc_pbuf_custom_ref(void)
hexley	0:281d6ff68967	625	{
hexley	0:281d6ff68967	626	return (struct pbuf_custom_ref*)memp_malloc(MEMP_FRAG_PBUF);
hexley	0:281d6ff68967	627	}
hexley	0:281d6ff68967	628
hexley	0:281d6ff68967	629	/** Free a struct pbuf_custom_ref */
hexley	0:281d6ff68967	630	static void
hexley	0:281d6ff68967	631	ip_frag_free_pbuf_custom_ref(struct pbuf_custom_ref* p)
hexley	0:281d6ff68967	632	{
hexley	0:281d6ff68967	633	LWIP_ASSERT("p != NULL", p != NULL);
hexley	0:281d6ff68967	634	memp_free(MEMP_FRAG_PBUF, p);
hexley	0:281d6ff68967	635	}
hexley	0:281d6ff68967	636
hexley	0:281d6ff68967	637	/** Free-callback function to free a 'struct pbuf_custom_ref', called by
hexley	0:281d6ff68967	638	* pbuf_free. */
hexley	0:281d6ff68967	639	static void
hexley	0:281d6ff68967	640	ipfrag_free_pbuf_custom(struct pbuf *p)
hexley	0:281d6ff68967	641	{
hexley	0:281d6ff68967	642	struct pbuf_custom_ref pcr = (struct pbuf_custom_ref)p;
hexley	0:281d6ff68967	643	LWIP_ASSERT("pcr != NULL", pcr != NULL);
hexley	0:281d6ff68967	644	LWIP_ASSERT("pcr == p", (void)pcr == (void)p);
hexley	0:281d6ff68967	645	if (pcr->original != NULL) {
hexley	0:281d6ff68967	646	pbuf_free(pcr->original);
hexley	0:281d6ff68967	647	}
hexley	0:281d6ff68967	648	ip_frag_free_pbuf_custom_ref(pcr);
hexley	0:281d6ff68967	649	}
hexley	0:281d6ff68967	650	#endif /* !LWIP_NETIF_TX_SINGLE_PBUF */
hexley	0:281d6ff68967	651	#endif /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	652
hexley	0:281d6ff68967	653	/**
hexley	0:281d6ff68967	654	* Fragment an IP datagram if too large for the netif.
hexley	0:281d6ff68967	655	*
hexley	0:281d6ff68967	656	* Chop the datagram in MTU sized chunks and send them in order
hexley	0:281d6ff68967	657	* by using a fixed size static memory buffer (PBUF_REF) or
hexley	0:281d6ff68967	658	* point PBUF_REFs into p (depending on IP_FRAG_USES_STATIC_BUF).
hexley	0:281d6ff68967	659	*
hexley	0:281d6ff68967	660	* @param p ip packet to send
hexley	0:281d6ff68967	661	* @param netif the netif on which to send
hexley	0:281d6ff68967	662	* @param dest destination ip address to which to send
hexley	0:281d6ff68967	663	*
hexley	0:281d6ff68967	664	* @return ERR_OK if sent successfully, err_t otherwise
hexley	0:281d6ff68967	665	*/
hexley	0:281d6ff68967	666	err_t
hexley	0:281d6ff68967	667	ip_frag(struct pbuf p, struct netif netif, ip_addr_t *dest)
hexley	0:281d6ff68967	668	{
hexley	0:281d6ff68967	669	struct pbuf *rambuf;
hexley	0:281d6ff68967	670	#if IP_FRAG_USES_STATIC_BUF
hexley	0:281d6ff68967	671	struct pbuf *header;
hexley	0:281d6ff68967	672	#else
hexley	0:281d6ff68967	673	#if !LWIP_NETIF_TX_SINGLE_PBUF
hexley	0:281d6ff68967	674	struct pbuf *newpbuf;
hexley	0:281d6ff68967	675	#endif
hexley	0:281d6ff68967	676	struct ip_hdr *original_iphdr;
hexley	0:281d6ff68967	677	#endif
hexley	0:281d6ff68967	678	struct ip_hdr *iphdr;
hexley	0:281d6ff68967	679	u16_t nfb;
hexley	0:281d6ff68967	680	u16_t left, cop;
hexley	0:281d6ff68967	681	u16_t mtu = netif->mtu;
hexley	0:281d6ff68967	682	u16_t ofo, omf;
hexley	0:281d6ff68967	683	u16_t last;
hexley	0:281d6ff68967	684	u16_t poff = IP_HLEN;
hexley	0:281d6ff68967	685	u16_t tmp;
hexley	0:281d6ff68967	686	#if !IP_FRAG_USES_STATIC_BUF && !LWIP_NETIF_TX_SINGLE_PBUF
hexley	0:281d6ff68967	687	u16_t newpbuflen = 0;
hexley	0:281d6ff68967	688	u16_t left_to_copy;
hexley	0:281d6ff68967	689	#endif
hexley	0:281d6ff68967	690
hexley	0:281d6ff68967	691	/* Get a RAM based MTU sized pbuf */
hexley	0:281d6ff68967	692	#if IP_FRAG_USES_STATIC_BUF
hexley	0:281d6ff68967	693	/* When using a static buffer, we use a PBUF_REF, which we will
hexley	0:281d6ff68967	694	* use to reference the packet (without link header).
hexley	0:281d6ff68967	695	* Layer and length is irrelevant.
hexley	0:281d6ff68967	696	*/
hexley	0:281d6ff68967	697	rambuf = pbuf_alloc(PBUF_LINK, 0, PBUF_REF);
hexley	0:281d6ff68967	698	if (rambuf == NULL) {
hexley	0:281d6ff68967	699	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc(PBUF_LINK, 0, PBUF_REF) failed\n"));
hexley	0:281d6ff68967	700	return ERR_MEM;
hexley	0:281d6ff68967	701	}
hexley	0:281d6ff68967	702	rambuf->tot_len = rambuf->len = mtu;
hexley	0:281d6ff68967	703	rambuf->payload = LWIP_MEM_ALIGN((void *)buf);
hexley	0:281d6ff68967	704
hexley	0:281d6ff68967	705	/* Copy the IP header in it */
hexley	0:281d6ff68967	706	iphdr = (struct ip_hdr *)rambuf->payload;
hexley	0:281d6ff68967	707	SMEMCPY(iphdr, p->payload, IP_HLEN);
hexley	0:281d6ff68967	708	#else /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	709	original_iphdr = (struct ip_hdr *)p->payload;
hexley	0:281d6ff68967	710	iphdr = original_iphdr;
hexley	0:281d6ff68967	711	#endif /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	712
hexley	0:281d6ff68967	713	/* Save original offset */
hexley	0:281d6ff68967	714	tmp = ntohs(IPH_OFFSET(iphdr));
hexley	0:281d6ff68967	715	ofo = tmp & IP_OFFMASK;
hexley	0:281d6ff68967	716	omf = tmp & IP_MF;
hexley	0:281d6ff68967	717
hexley	0:281d6ff68967	718	left = p->tot_len - IP_HLEN;
hexley	0:281d6ff68967	719
hexley	0:281d6ff68967	720	nfb = (mtu - IP_HLEN) / 8;
hexley	0:281d6ff68967	721
hexley	0:281d6ff68967	722	while (left) {
hexley	0:281d6ff68967	723	last = (left <= mtu - IP_HLEN);
hexley	0:281d6ff68967	724
hexley	0:281d6ff68967	725	/* Set new offset and MF flag */
hexley	0:281d6ff68967	726	tmp = omf \| (IP_OFFMASK & (ofo));
hexley	0:281d6ff68967	727	if (!last) {
hexley	0:281d6ff68967	728	tmp = tmp \| IP_MF;
hexley	0:281d6ff68967	729	}
hexley	0:281d6ff68967	730
hexley	0:281d6ff68967	731	/* Fill this fragment */
hexley	0:281d6ff68967	732	cop = last ? left : nfb * 8;
hexley	0:281d6ff68967	733
hexley	0:281d6ff68967	734	#if IP_FRAG_USES_STATIC_BUF
hexley	0:281d6ff68967	735	poff += pbuf_copy_partial(p, (u8_t*)iphdr + IP_HLEN, cop, poff);
hexley	0:281d6ff68967	736	#else /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	737	#if LWIP_NETIF_TX_SINGLE_PBUF
hexley	0:281d6ff68967	738	rambuf = pbuf_alloc(PBUF_IP, cop, PBUF_RAM);
hexley	0:281d6ff68967	739	if (rambuf == NULL) {
hexley	0:281d6ff68967	740	return ERR_MEM;
hexley	0:281d6ff68967	741	}
hexley	0:281d6ff68967	742	LWIP_ASSERT("this needs a pbuf in one piece!",
hexley	0:281d6ff68967	743	(rambuf->len == rambuf->tot_len) && (rambuf->next == NULL));
hexley	0:281d6ff68967	744	poff += pbuf_copy_partial(p, rambuf->payload, cop, poff);
hexley	0:281d6ff68967	745	/* make room for the IP header */
hexley	0:281d6ff68967	746	if(pbuf_header(rambuf, IP_HLEN)) {
hexley	0:281d6ff68967	747	pbuf_free(rambuf);
hexley	0:281d6ff68967	748	return ERR_MEM;
hexley	0:281d6ff68967	749	}
hexley	0:281d6ff68967	750	/* fill in the IP header */
hexley	0:281d6ff68967	751	SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
hexley	0:281d6ff68967	752	iphdr = rambuf->payload;
hexley	0:281d6ff68967	753	#else /* LWIP_NETIF_TX_SINGLE_PBUF */
hexley	0:281d6ff68967	754	/* When not using a static buffer, create a chain of pbufs.
hexley	0:281d6ff68967	755	* The first will be a PBUF_RAM holding the link and IP header.
hexley	0:281d6ff68967	756	* The rest will be PBUF_REFs mirroring the pbuf chain to be fragged,
hexley	0:281d6ff68967	757	* but limited to the size of an mtu.
hexley	0:281d6ff68967	758	*/
hexley	0:281d6ff68967	759	rambuf = pbuf_alloc(PBUF_LINK, IP_HLEN, PBUF_RAM);
hexley	0:281d6ff68967	760	if (rambuf == NULL) {
hexley	0:281d6ff68967	761	return ERR_MEM;
hexley	0:281d6ff68967	762	}
hexley	0:281d6ff68967	763	LWIP_ASSERT("this needs a pbuf in one piece!",
hexley	0:281d6ff68967	764	(p->len >= (IP_HLEN)));
hexley	0:281d6ff68967	765	SMEMCPY(rambuf->payload, original_iphdr, IP_HLEN);
hexley	0:281d6ff68967	766	iphdr = (struct ip_hdr *)rambuf->payload;
hexley	0:281d6ff68967	767
hexley	0:281d6ff68967	768	/* Can just adjust p directly for needed offset. */
hexley	0:281d6ff68967	769	p->payload = (u8_t *)p->payload + poff;
hexley	0:281d6ff68967	770	p->len -= poff;
hexley	0:281d6ff68967	771
hexley	0:281d6ff68967	772	left_to_copy = cop;
hexley	0:281d6ff68967	773	while (left_to_copy) {
hexley	0:281d6ff68967	774	struct pbuf_custom_ref *pcr;
hexley	0:281d6ff68967	775	newpbuflen = (left_to_copy < p->len) ? left_to_copy : p->len;
hexley	0:281d6ff68967	776	/* Is this pbuf already empty? */
hexley	0:281d6ff68967	777	if (!newpbuflen) {
hexley	0:281d6ff68967	778	p = p->next;
hexley	0:281d6ff68967	779	continue;
hexley	0:281d6ff68967	780	}
hexley	0:281d6ff68967	781	pcr = ip_frag_alloc_pbuf_custom_ref();
hexley	0:281d6ff68967	782	if (pcr == NULL) {
hexley	0:281d6ff68967	783	pbuf_free(rambuf);
hexley	0:281d6ff68967	784	return ERR_MEM;
hexley	0:281d6ff68967	785	}
hexley	0:281d6ff68967	786	/* Mirror this pbuf, although we might not need all of it. */
hexley	0:281d6ff68967	787	newpbuf = pbuf_alloced_custom(PBUF_RAW, newpbuflen, PBUF_REF, &pcr->pc, p->payload, newpbuflen);
hexley	0:281d6ff68967	788	if (newpbuf == NULL) {
hexley	0:281d6ff68967	789	ip_frag_free_pbuf_custom_ref(pcr);
hexley	0:281d6ff68967	790	pbuf_free(rambuf);
hexley	0:281d6ff68967	791	return ERR_MEM;
hexley	0:281d6ff68967	792	}
hexley	0:281d6ff68967	793	pbuf_ref(p);
hexley	0:281d6ff68967	794	pcr->original = p;
hexley	0:281d6ff68967	795	pcr->pc.custom_free_function = ipfrag_free_pbuf_custom;
hexley	0:281d6ff68967	796
hexley	0:281d6ff68967	797	/* Add it to end of rambuf's chain, but using pbuf_cat, not pbuf_chain
hexley	0:281d6ff68967	798	* so that it is removed when pbuf_dechain is later called on rambuf.
hexley	0:281d6ff68967	799	*/
hexley	0:281d6ff68967	800	pbuf_cat(rambuf, newpbuf);
hexley	0:281d6ff68967	801	left_to_copy -= newpbuflen;
hexley	0:281d6ff68967	802	if (left_to_copy) {
hexley	0:281d6ff68967	803	p = p->next;
hexley	0:281d6ff68967	804	}
hexley	0:281d6ff68967	805	}
hexley	0:281d6ff68967	806	poff = newpbuflen;
hexley	0:281d6ff68967	807	#endif /* LWIP_NETIF_TX_SINGLE_PBUF */
hexley	0:281d6ff68967	808	#endif /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	809
hexley	0:281d6ff68967	810	/* Correct header */
hexley	0:281d6ff68967	811	IPH_OFFSET_SET(iphdr, htons(tmp));
hexley	0:281d6ff68967	812	IPH_LEN_SET(iphdr, htons(cop + IP_HLEN));
hexley	0:281d6ff68967	813	IPH_CHKSUM_SET(iphdr, 0);
hexley	0:281d6ff68967	814	IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
hexley	0:281d6ff68967	815
hexley	0:281d6ff68967	816	#if IP_FRAG_USES_STATIC_BUF
hexley	0:281d6ff68967	817	if (last) {
hexley	0:281d6ff68967	818	pbuf_realloc(rambuf, left + IP_HLEN);
hexley	0:281d6ff68967	819	}
hexley	0:281d6ff68967	820
hexley	0:281d6ff68967	821	/* This part is ugly: we alloc a RAM based pbuf for
hexley	0:281d6ff68967	822	* the link level header for each chunk and then
hexley	0:281d6ff68967	823	* free it.A PBUF_ROM style pbuf for which pbuf_header
hexley	0:281d6ff68967	824	* worked would make things simpler.
hexley	0:281d6ff68967	825	*/
hexley	0:281d6ff68967	826	header = pbuf_alloc(PBUF_LINK, 0, PBUF_RAM);
hexley	0:281d6ff68967	827	if (header != NULL) {
hexley	0:281d6ff68967	828	pbuf_chain(header, rambuf);
hexley	0:281d6ff68967	829	netif->output(netif, header, dest);
hexley	0:281d6ff68967	830	IPFRAG_STATS_INC(ip_frag.xmit);
hexley	0:281d6ff68967	831	snmp_inc_ipfragcreates();
hexley	0:281d6ff68967	832	pbuf_free(header);
hexley	0:281d6ff68967	833	} else {
hexley	0:281d6ff68967	834	LWIP_DEBUGF(IP_REASS_DEBUG, ("ip_frag: pbuf_alloc() for header failed\n"));
hexley	0:281d6ff68967	835	pbuf_free(rambuf);
hexley	0:281d6ff68967	836	return ERR_MEM;
hexley	0:281d6ff68967	837	}
hexley	0:281d6ff68967	838	#else /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	839	/* No need for separate header pbuf - we allowed room for it in rambuf
hexley	0:281d6ff68967	840	* when allocated.
hexley	0:281d6ff68967	841	*/
hexley	0:281d6ff68967	842	netif->output(netif, rambuf, dest);
hexley	0:281d6ff68967	843	IPFRAG_STATS_INC(ip_frag.xmit);
hexley	0:281d6ff68967	844
hexley	0:281d6ff68967	845	/* Unfortunately we can't reuse rambuf - the hardware may still be
hexley	0:281d6ff68967	846	* using the buffer. Instead we free it (and the ensuing chain) and
hexley	0:281d6ff68967	847	* recreate it next time round the loop. If we're lucky the hardware
hexley	0:281d6ff68967	848	* will have already sent the packet, the free will really free, and
hexley	0:281d6ff68967	849	* there will be zero memory penalty.
hexley	0:281d6ff68967	850	*/
hexley	0:281d6ff68967	851
hexley	0:281d6ff68967	852	pbuf_free(rambuf);
hexley	0:281d6ff68967	853	#endif /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	854	left -= cop;
hexley	0:281d6ff68967	855	ofo += nfb;
hexley	0:281d6ff68967	856	}
hexley	0:281d6ff68967	857	#if IP_FRAG_USES_STATIC_BUF
hexley	0:281d6ff68967	858	pbuf_free(rambuf);
hexley	0:281d6ff68967	859	#endif /* IP_FRAG_USES_STATIC_BUF */
hexley	0:281d6ff68967	860	snmp_inc_ipfragoks();
hexley	0:281d6ff68967	861	return ERR_OK;
hexley	0:281d6ff68967	862	}
hexley	0:281d6ff68967	863	#endif /* IP_FRAG */

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Type:	Library
Created:	19 Nov 2010
Imports:	44
Forks:	0
Commits:	1
Dependents:	0
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lwip/core/ipv4/ip_frag.c@0:281d6ff68967, 2010-11-19 (annotated)

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