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wireshark/reassemble.c

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/* reassemble.c
* Routines for {fragment,segment} reassembly
*
* $Id: reassemble.c,v 1.39 2003/06/04 05:41:37 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
* Copyright 1998 Gerald Combs
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <string.h>
#include <epan/packet.h>
#include "reassemble.h"
typedef struct _fragment_key {
address src;
address dst;
guint32 id;
} fragment_key;
static GMemChunk *fragment_key_chunk = NULL;
static GMemChunk *fragment_data_chunk = NULL;
static int fragment_init_count = 200;
#define LINK_FRAG(fd_head,fd) \
{ fragment_data *fd_i; \
/* add fragment to list, keep list sorted */ \
for(fd_i=(fd_head);fd_i->next;fd_i=fd_i->next){ \
if( ((fd)->offset) < (fd_i->next->offset) ) \
break; \
} \
(fd)->next=fd_i->next; \
fd_i->next=(fd); \
}
static gint
fragment_equal(gconstpointer k1, gconstpointer k2)
{
const fragment_key* key1 = (const fragment_key*) k1;
const fragment_key* key2 = (const fragment_key*) k2;
/*key.id is the first item to compare since item is most
likely to differ between sessions, thus shortcircuiting
the comparasion of addresses.
*/
return ( ( (key1->id == key2->id) &&
(ADDRESSES_EQUAL(&key1->src, &key2->src)) &&
(ADDRESSES_EQUAL(&key1->dst, &key2->dst))
) ?
TRUE : FALSE);
}
static guint
fragment_hash(gconstpointer k)
{
const fragment_key* key = (const fragment_key*) k;
guint hash_val;
/*
int i;
*/
hash_val = 0;
/* More than likely: in most captures src and dst addresses are the
same, and would hash the same.
We only use id as the hash as an optimization.
for (i = 0; i < key->src.len; i++)
hash_val += key->src.data[i];
for (i = 0; i < key->dst.len; i++)
hash_val += key->dst.data[i];
*/
hash_val += key->id;
return hash_val;
}
typedef struct _reassembled_key {
guint32 id;
guint32 frame;
} reassembled_key;
static GMemChunk *reassembled_key_chunk = NULL;
static gint
reassembled_equal(gconstpointer k1, gconstpointer k2)
{
const reassembled_key* key1 = (const reassembled_key*) k1;
const reassembled_key* key2 = (const reassembled_key*) k2;
/*
* We assume that the frame numbers are unlikely to be equal,
* so we check them first.
*/
return key1->frame == key2->frame && key1->id == key2->id;
}
static guint
reassembled_hash(gconstpointer k)
{
const reassembled_key* key = (const reassembled_key*) k;
return key->frame;
}
/*
* For a fragment hash table entry, free the address data to which the key
* refers and the fragment data to which the value refers.
* (The actual key and value structures get freed by "reassemble_init()".)
*/
static gboolean
free_all_fragments(gpointer key_arg, gpointer value, gpointer user_data _U_)
{
fragment_key *key = key_arg;
fragment_data *fd_head;
/*
* Grr. I guess the theory here is that freeing
* something sure as heck modifies it, so you
* want to ban attempts to free it, but, alas,
* if we make the "data" field of an "address"
* structure not a "const", the compiler whines if
* we try to make it point into the data for a packet,
* as that's a "const" array (and should be, as dissectors
* shouldn't trash it).
*
* So we cast the complaint into oblivion, and rely on
* the fact that these addresses are known to have had
* their data mallocated, i.e. they don't point into,
* say, the middle of the data for a packet.
*/
g_free((gpointer)key->src.data);
g_free((gpointer)key->dst.data);
for (fd_head = value; fd_head != NULL; fd_head = fd_head->next) {
if(fd_head->data && !(fd_head->flags&FD_NOT_MALLOCED))
g_free(fd_head->data);
}
return TRUE;
}
/*
* For a reassembled-packet hash table entry, free the fragment data
* to which the value refers.
* (The actual value structures get freed by "reassemble_init()".)
*/
static gboolean
free_all_reassembled_fragments(gpointer key_arg _U_, gpointer value,
gpointer user_data _U_)
{
fragment_data *fd_head;
for (fd_head = value; fd_head != NULL; fd_head = fd_head->next) {
if(fd_head->data && !(fd_head->flags&FD_NOT_MALLOCED)) {
g_free(fd_head->data);
/*
* A reassembled packet is inserted into the
* hash table once for every frame that made
* up the reassembled packet; clear the data
* pointer so that we only free the data the
* first time we see it.
*/
fd_head->data = NULL;
}
}
return TRUE;
}
/*
* Initialize a fragment table.
*/
void
fragment_table_init(GHashTable **fragment_table)
{
if (*fragment_table != NULL) {
/*
* The fragment hash table exists.
*
* Remove all entries and free fragment data for
* each entry. (The key and value data is freed
* by "reassemble_init()".)
*/
g_hash_table_foreach_remove(*fragment_table,
free_all_fragments, NULL);
} else {
/* The fragment table does not exist. Create it */
*fragment_table = g_hash_table_new(fragment_hash,
fragment_equal);
}
}
/*
* Initialize a reassembled-packet table.
*/
void
reassembled_table_init(GHashTable **reassembled_table)
{
if (*reassembled_table != NULL) {
/*
* The reassembled-packet hash table exists.
*
* Remove all entries and free reassembled packet
* data for each entry. (The key data is freed
* by "reassemble_init()".)
*/
g_hash_table_foreach_remove(*reassembled_table,
free_all_reassembled_fragments, NULL);
} else {
/* The fragment table does not exist. Create it */
*reassembled_table = g_hash_table_new(reassembled_hash,
reassembled_equal);
}
}
/*
* Free up all space allocated for fragment keys and data and
* reassembled keys.
*/
void
reassemble_init(void)
{
if (fragment_key_chunk != NULL)
g_mem_chunk_destroy(fragment_key_chunk);
if (fragment_data_chunk != NULL)
g_mem_chunk_destroy(fragment_data_chunk);
if (reassembled_key_chunk != NULL)
g_mem_chunk_destroy(reassembled_key_chunk);
fragment_key_chunk = g_mem_chunk_new("fragment_key_chunk",
sizeof(fragment_key),
fragment_init_count * sizeof(fragment_key),
G_ALLOC_AND_FREE);
fragment_data_chunk = g_mem_chunk_new("fragment_data_chunk",
sizeof(fragment_data),
fragment_init_count * sizeof(fragment_data),
G_ALLOC_ONLY);
reassembled_key_chunk = g_mem_chunk_new("reassembled_key_chunk",
sizeof(reassembled_key),
fragment_init_count * sizeof(reassembled_key),
G_ALLOC_AND_FREE);
}
/* This function cleans up the stored state and removes the reassembly data and
* (with one exception) all allocated memory for matching reassembly.
*
* The exception is :
* If the PDU was already completely reassembled, then the buffer containing the
* reassembled data WILL NOT be free()d, and the pointer to that buffer will be
* returned.
* Othervise the function will return NULL.
*
* So, if you call fragment_delete and it returns non-NULL, YOU are responsible to
* g_free() that buffer.
*/
unsigned char *
fragment_delete(packet_info *pinfo, guint32 id, GHashTable *fragment_table)
{
fragment_data *fd_head, *fd;
fragment_key key;
unsigned char *data=NULL;
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
fd_head = g_hash_table_lookup(fragment_table, &key);
if(fd_head==NULL){
/* We do not recognize this as a PDU we have seen before. return*/
return NULL;
}
data=fd_head->data;
/* loop over all partial fragments and free any buffers */
for(fd=fd_head->next;fd;){
fragment_data *tmp_fd;
tmp_fd=fd->next;
if( !(fd->flags&FD_NOT_MALLOCED) )
g_free(fd->data);
g_mem_chunk_free(fragment_data_chunk, fd);
fd=tmp_fd;
}
g_mem_chunk_free(fragment_data_chunk, fd_head);
g_hash_table_remove(fragment_table, &key);
return data;
}
/* This function is used to check if there is partial or completed reassembly state
* matching this packet. I.e. Are there reassembly going on or not for this packet?
*/
fragment_data *
fragment_get(packet_info *pinfo, guint32 id, GHashTable *fragment_table)
{
fragment_data *fd_head;
fragment_key key;
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
fd_head = g_hash_table_lookup(fragment_table, &key);
return fd_head;
}
/* This function can be used to explicitely set the total length (if known)
* for reassembly of a PDU.
* This is useful for reassembly of PDUs where one may have the total length specified
* in the first fragment instead of as for, say, IPv4 where a flag indicates which
* is the last fragment.
*
* Such protocols might fragment_add with a more_frags==TRUE for every fragment
* and just tell the reassembly engine the expected total length of the reassembled data
* using fragment_set_tot_len immediately after doing fragment_add for the first packet.
*
* note that for FD_BLOCKSEQUENCE tot_len is the index for the tail fragment.
* i.e. since the block numbers start at 0, if we specify tot_len==2, that
* actually means we want to defragment 3 blocks, block 0, 1 and 2.
*/
void
fragment_set_tot_len(packet_info *pinfo, guint32 id, GHashTable *fragment_table,
guint32 tot_len)
{
fragment_data *fd_head;
fragment_key key;
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
fd_head = g_hash_table_lookup(fragment_table, &key);
if(fd_head){
fd_head->datalen = tot_len;
}
return;
}
guint32
fragment_get_tot_len(packet_info *pinfo, guint32 id, GHashTable *fragment_table)
{
fragment_data *fd_head;
fragment_key key;
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
fd_head = g_hash_table_lookup(fragment_table, &key);
if(fd_head){
return fd_head->datalen;
}
return 0;
}
/* This function will set the partial reassembly flag for a fh.
When this function is called, the fh MUST already exist, i.e.
the fh MUST be created by the initial call to fragment_add() before
this function is called.
Also note that this function MUST be called to indicate a fh will be
extended (increase the already stored data)
*/
void
fragment_set_partial_reassembly(packet_info *pinfo, guint32 id, GHashTable *fragment_table)
{
fragment_data *fd_head;
fragment_key key;
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
fd_head = g_hash_table_lookup(fragment_table, &key);
if(fd_head){
fd_head->flags |= FD_PARTIAL_REASSEMBLY;
}
}
/*
* This function gets rid of an entry from a fragment table, given
* a pointer to the key for that entry; it also frees up the key
* and the addresses in it.
*/
static void
fragment_unhash(GHashTable *fragment_table, fragment_key *key)
{
/*
* Free up the copies of the addresses from the old key.
*/
g_free((gpointer)key->src.data);
g_free((gpointer)key->dst.data);
/*
* Remove the entry from the fragment table.
*/
g_hash_table_remove(fragment_table, key);
/*
* Free the key itself.
*/
g_mem_chunk_free(fragment_key_chunk, key);
}
/*
* This function adds fragment_data structure to a reassembled-packet
* hash table, using the frame numbers of each of the frames from
* which it was reassembled as keys, and sets the "reassembled_in"
* frame number.
*/
static void
fragment_reassembled(fragment_data *fd_head, packet_info *pinfo,
GHashTable *reassembled_table, guint32 id)
{
reassembled_key *new_key;
fragment_data *fd;
if (fd_head->next == NULL) {
/*
* This was not fragmented, so there's no fragment
* table; just hash it using the current frame number.
*/
new_key = g_mem_chunk_alloc(reassembled_key_chunk);
new_key->frame = pinfo->fd->num;
new_key->id = id;
g_hash_table_insert(reassembled_table, new_key, fd_head);
} else {
/*
* Hash it with the frame numbers for all the frames.
*/
for (fd = fd_head->next; fd != NULL; fd = fd->next){
new_key = g_mem_chunk_alloc(reassembled_key_chunk);
new_key->frame = fd->frame;
new_key->id = id;
g_hash_table_insert(reassembled_table, new_key,
fd_head);
}
}
fd_head->reassembled_in = pinfo->fd->num;
}
/*
* This function adds a new fragment to the fragment hash table.
* If this is the first fragment seen for this datagram, a new entry
* is created in the hash table, otherwise this fragment is just added
* to the linked list of fragments for this packet.
* The list of fragments for a specific datagram is kept sorted for
* easier handling.
*
* Returns a pointer to the head of the fragment data list if we have all the
* fragments, NULL otherwise.
*
* This function assumes frag_offset being a byte offset into the defragment
* packet.
*
* 01-2002
* Once the fh is defragmented (= FD_DEFRAGMENTED set), it can be
* extended using the FD_PARTIAL_REASSEMBLY flag. This flag should be set
* using fragment_set_partial_reassembly() before calling fragment_add
* with the new fragment. FD_TOOLONGFRAGMENT and FD_MULTIPLETAILS flags
* are lowered when a new extension process is started.
*/
static gboolean
fragment_add_work(fragment_data *fd_head, tvbuff_t *tvb, int offset,
packet_info *pinfo, guint32 frag_offset,
guint32 frag_data_len, gboolean more_frags)
{
fragment_data *fd;
fragment_data *fd_i;
guint32 max, dfpos;
unsigned char *old_data;
/* create new fd describing this fragment */
fd = g_mem_chunk_alloc(fragment_data_chunk);
fd->next = NULL;
fd->flags = 0;
fd->frame = pinfo->fd->num;
fd->offset = frag_offset;
fd->len = frag_data_len;
fd->data = NULL;
/*
* If it was already defragmented and this new fragment goes beyond
* data limits, set flag in already empty fds & point old fds to malloc'ed data.
*/
if(fd_head->flags & FD_DEFRAGMENTED && (frag_offset+frag_data_len) >= fd_head->datalen &&
fd_head->flags & FD_PARTIAL_REASSEMBLY){
for(fd_i=fd_head->next; fd_i; fd_i=fd_i->next){
if( !fd_i->data ) {
fd_i->data = fd_head->data + fd_i->offset;
fd_i->flags |= FD_NOT_MALLOCED;
}
fd_i->flags &= (~FD_TOOLONGFRAGMENT) & (~FD_MULTIPLETAILS);
}
fd_head->flags ^= FD_DEFRAGMENTED|FD_PARTIAL_REASSEMBLY;
fd_head->flags &= (~FD_TOOLONGFRAGMENT) & (~FD_MULTIPLETAILS);
fd_head->datalen=0;
}
if (!more_frags) {
/*
* This is the tail fragment in the sequence.
*/
if (fd_head->datalen) {
/* ok we have already seen other tails for this packet
* it might be a duplicate.
*/
if (fd_head->datalen != (fd->offset + fd->len) ){
/* Oops, this tail indicates a different packet
* len than the previous ones. Somethings wrong
*/
fd->flags |= FD_MULTIPLETAILS;
fd_head->flags |= FD_MULTIPLETAILS;
}
} else {
/* this was the first tail fragment, now we know the
* length of the packet
*/
fd_head->datalen = fd->offset + fd->len;
}
}
/* If the packet is already defragmented, this MUST be an overlap.
* The entire defragmented packet is in fd_head->data
* Even if we have previously defragmented this packet, we still check
* check it. Someone might play overlap and TTL games.
*/
if (fd_head->flags & FD_DEFRAGMENTED) {
fd->flags |= FD_OVERLAP;
fd_head->flags |= FD_OVERLAP;
/* make sure its not too long */
if (fd->offset + fd->len > fd_head->datalen) {
fd->flags |= FD_TOOLONGFRAGMENT;
fd_head->flags |= FD_TOOLONGFRAGMENT;
LINK_FRAG(fd_head,fd);
return TRUE;
}
/* make sure it doesnt conflict with previous data */
if ( memcmp(fd_head->data+fd->offset,
tvb_get_ptr(tvb,offset,fd->len),fd->len) ){
fd->flags |= FD_OVERLAPCONFLICT;
fd_head->flags |= FD_OVERLAPCONFLICT;
LINK_FRAG(fd_head,fd);
return TRUE;
}
/* it was just an overlap, link it and return */
LINK_FRAG(fd_head,fd);
return TRUE;
}
/* If we have reached this point, the packet is not defragmented yet.
* Save all payload in a buffer until we can defragment.
* XXX - what if we didn't capture the entire fragment due
* to a too-short snapshot length?
*/
fd->data = g_malloc(fd->len);
tvb_memcpy(tvb, fd->data, offset, fd->len);
LINK_FRAG(fd_head,fd);
if( !(fd_head->datalen) ){
/* if we dont know the datalen, there are still missing
* packets. Cheaper than the check below.
*/
return FALSE;
}
/* check if we have received the entire fragment
* this is easy since the list is sorted and the head is faked.
*/
max = 0;
for (fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
if ( ((fd_i->offset)<=max) &&
((fd_i->offset+fd_i->len)>max) ){
max = fd_i->offset+fd_i->len;
}
}
if (max < (fd_head->datalen)) {
/* we have not received all packets yet */
return FALSE;
}
if (max > (fd_head->datalen)) {
/*XXX not sure if current fd was the TOOLONG*/
/*XXX is it fair to flag current fd*/
/* oops, too long fragment detected */
fd->flags |= FD_TOOLONGFRAGMENT;
fd_head->flags |= FD_TOOLONGFRAGMENT;
}
/* we have received an entire packet, defragment it and
* free all fragments
*/
/* store old data just in case */
old_data=fd_head->data;
fd_head->data = g_malloc(max);
/* add all data fragments */
for (dfpos=0,fd_i=fd_head;fd_i;fd_i=fd_i->next) {
if (fd_i->len) {
if (fd_i->offset < dfpos) {
fd_i->flags |= FD_OVERLAP;
fd_head->flags |= FD_OVERLAP;
if ( memcmp(fd_head->data+fd_i->offset,
fd_i->data,
MIN(fd_i->len,(dfpos-fd_i->offset))
) ){
fd_i->flags |= FD_OVERLAPCONFLICT;
fd_head->flags |= FD_OVERLAPCONFLICT;
}
}
/* dfpos is always >= than fd_i->offset */
/* No gaps can exist here, max_loop(above) does this */
if( fd_i->offset+fd_i->len > dfpos )
memcpy(fd_head->data+dfpos, fd_i->data+(dfpos-fd_i->offset),
fd_i->len-(dfpos-fd_i->offset));
if( fd_i->flags & FD_NOT_MALLOCED )
fd_i->flags ^= FD_NOT_MALLOCED;
else
g_free(fd_i->data);
fd_i->data=NULL;
dfpos=MAX(dfpos,(fd_i->offset+fd_i->len));
}
}
if( old_data )
g_free(old_data);
/* mark this packet as defragmented.
allows us to skip any trailing fragments */
fd_head->flags |= FD_DEFRAGMENTED;
fd_head->reassembled_in=pinfo->fd->num;
return TRUE;
}
fragment_data *
fragment_add_common(tvbuff_t *tvb, int offset, packet_info *pinfo, guint32 id,
GHashTable *fragment_table, guint32 frag_offset,
guint32 frag_data_len, gboolean more_frags,
gboolean check_already_added)
{
fragment_key key, *new_key;
fragment_data *fd_head;
fragment_data *fd_item;
gboolean already_added=pinfo->fd->flags.visited;
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
fd_head = g_hash_table_lookup(fragment_table, &key);
/*
* "already_added" is true if "pinfo->fd->flags.visited" is true;
* if "pinfo->fd->flags.visited", this isn't the first pass, so
* we've already done all the reassembly and added all the
* fragments.
*
* If it's not true, but "check_already_added" is true, just check
* if we have seen this fragment before, i.e., if we have already
* added it to reassembly.
* That can be true even if "pinfo->fd->flags.visited" is false
* since we sometimes might call a subdissector multiple times.
* As an additional check, just make sure we have not already added
* this frame to the reassembly list, if there is a reassembly list;
* note that the first item in the reassembly list is not a
* fragment, it's a data structure for the reassembled packet.
* We don't check it because its "frame" member isn't initialized
* to anything, and because it doesn't count in any case.
*/
if (!already_added && check_already_added && fd_head != NULL) {
for(fd_item=fd_head->next;fd_item;fd_item=fd_item->next){
if(pinfo->fd->num==fd_item->frame){
already_added=TRUE;
}
}
}
/* have we already added this frame ?*/
if (already_added) {
if (fd_head != NULL && fd_head->flags & FD_DEFRAGMENTED) {
return fd_head;
} else {
return NULL;
}
}
if (fd_head==NULL){
/* not found, this must be the first snooped fragment for this
* packet. Create list-head.
*/
fd_head=g_mem_chunk_alloc(fragment_data_chunk);
/* head/first structure in list only holds no other data than
* 'datalen' then we don't have to change the head of the list
* even if we want to keep it sorted
*/
fd_head->next=NULL;
fd_head->datalen=0;
fd_head->offset=0;
fd_head->len=0;
fd_head->flags=0;
fd_head->data=NULL;
fd_head->reassembled_in=0;
/*
* We're going to use the key to insert the fragment,
* so allocate a structure for it, and copy the
* addresses, allocating new buffers for the address
* data.
*/
new_key = g_mem_chunk_alloc(fragment_key_chunk);
COPY_ADDRESS(&new_key->src, &key.src);
COPY_ADDRESS(&new_key->dst, &key.dst);
new_key->id = key.id;
g_hash_table_insert(fragment_table, new_key, fd_head);
}
if (fragment_add_work(fd_head, tvb, offset, pinfo, frag_offset,
frag_data_len, more_frags)) {
/*
* Reassembly is complete.
*/
return fd_head;
} else {
/*
* Reassembly isn't complete.
*/
return NULL;
}
}
fragment_data *
fragment_add(tvbuff_t *tvb, int offset, packet_info *pinfo, guint32 id,
GHashTable *fragment_table, guint32 frag_offset,
guint32 frag_data_len, gboolean more_frags)
{
return fragment_add_common(tvb, offset, pinfo, id, fragment_table,
frag_offset, frag_data_len, more_frags, TRUE);
}
/*
* For use when you can have multiple fragments in the same frame added
* to the same reassembled PDU, e.g. with ONC RPC-over-TCP.
*/
fragment_data *
fragment_add_multiple_ok(tvbuff_t *tvb, int offset, packet_info *pinfo,
guint32 id, GHashTable *fragment_table,
guint32 frag_offset, guint32 frag_data_len,
gboolean more_frags)
{
return fragment_add_common(tvb, offset, pinfo, id, fragment_table,
frag_offset, frag_data_len, more_frags, FALSE);
}
fragment_data *
fragment_add_check(tvbuff_t *tvb, int offset, packet_info *pinfo,
guint32 id, GHashTable *fragment_table,
GHashTable *reassembled_table, guint32 frag_offset,
guint32 frag_data_len, gboolean more_frags)
{
reassembled_key reass_key;
fragment_key key, *new_key, *old_key;
gpointer orig_key, value;
fragment_data *fd_head;
/*
* If this isn't the first pass, look for this frame in the table
* of reassembled packets.
*/
if (pinfo->fd->flags.visited) {
reass_key.frame = pinfo->fd->num;
reass_key.id = id;
return g_hash_table_lookup(reassembled_table, &reass_key);
}
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
if (!g_hash_table_lookup_extended(fragment_table, &key,
&orig_key, &value)) {
/* not found, this must be the first snooped fragment for this
* packet. Create list-head.
*/
fd_head=g_mem_chunk_alloc(fragment_data_chunk);
/* head/first structure in list only holds no other data than
* 'datalen' then we don't have to change the head of the list
* even if we want to keep it sorted
*/
fd_head->next=NULL;
fd_head->datalen=0;
fd_head->offset=0;
fd_head->len=0;
fd_head->flags=0;
fd_head->data=NULL;
fd_head->reassembled_in=0;
/*
* We're going to use the key to insert the fragment,
* so allocate a structure for it, and copy the
* addresses, allocating new buffers for the address
* data.
*/
new_key = g_mem_chunk_alloc(fragment_key_chunk);
COPY_ADDRESS(&new_key->src, &key.src);
COPY_ADDRESS(&new_key->dst, &key.dst);
new_key->id = key.id;
g_hash_table_insert(fragment_table, new_key, fd_head);
orig_key = new_key; /* for unhashing it later */
} else {
/*
* We found it.
*/
fd_head = value;
}
/*
* If this is a short frame, then we can't, and don't, do
* reassembly on it. We just give up.
*/
if (tvb_reported_length(tvb) > tvb_length(tvb))
return NULL;
if (fragment_add_work(fd_head, tvb, offset, pinfo, frag_offset,
frag_data_len, more_frags)) {
/*
* Reassembly is complete.
* Remove this from the table of in-progress
* reassemblies, add it to the table of
* reassembled packets, and return it.
*/
/*
* Remove this from the table of in-progress reassemblies,
* and free up any memory used for it in that table.
*/
old_key = orig_key;
fragment_unhash(fragment_table, old_key);
/*
* Add this item to the table of reassembled packets.
*/
fragment_reassembled(fd_head, pinfo, reassembled_table, id);
return fd_head;
} else {
/*
* Reassembly isn't complete.
*/
return NULL;
}
}
/*
* This function adds a new fragment to the entry for a reassembly
* operation.
*
* The list of fragments for a specific datagram is kept sorted for
* easier handling.
*
* Returns TRUE if we have all the fragments, FALSE otherwise.
*
* This function assumes frag_number being a block sequence number.
* The bsn for the first block is 0.
*/
static gboolean
fragment_add_seq_work(fragment_data *fd_head, tvbuff_t *tvb, int offset,
packet_info *pinfo, guint32 frag_number,
guint32 frag_data_len, gboolean more_frags)
{
fragment_data *fd;
fragment_data *fd_i;
fragment_data *last_fd;
guint32 max, dfpos, size;
/* create new fd describing this fragment */
fd = g_mem_chunk_alloc(fragment_data_chunk);
fd->next = NULL;
fd->flags = 0;
fd->frame = pinfo->fd->num;
fd->offset = frag_number;
fd->len = frag_data_len;
fd->data = NULL;
if (!more_frags) {
/*
* This is the tail fragment in the sequence.
*/
if (fd_head->datalen) {
/* ok we have already seen other tails for this packet
* it might be a duplicate.
*/
if (fd_head->datalen != fd->offset ){
/* Oops, this tail indicates a different packet
* len than the previous ones. Somethings wrong
*/
fd->flags |= FD_MULTIPLETAILS;
fd_head->flags |= FD_MULTIPLETAILS;
}
} else {
/* this was the first tail fragment, now we know the
* sequence number of that fragment (which is NOT
* the length of the packet!)
*/
fd_head->datalen = fd->offset;
}
}
/* If the packet is already defragmented, this MUST be an overlap.
* The entire defragmented packet is in fd_head->data
* Even if we have previously defragmented this packet, we still check
* check it. Someone might play overlap and TTL games.
*/
if (fd_head->flags & FD_DEFRAGMENTED) {
fd->flags |= FD_OVERLAP;
fd_head->flags |= FD_OVERLAP;
/* make sure it's not past the end */
if (fd->offset > fd_head->datalen) {
/* new fragment comes after the end */
fd->flags |= FD_TOOLONGFRAGMENT;
fd_head->flags |= FD_TOOLONGFRAGMENT;
LINK_FRAG(fd_head,fd);
return TRUE;
}
/* make sure it doesnt conflict with previous data */
dfpos=0;
last_fd=NULL;
for (fd_i=fd_head->next;fd_i->offset!=fd->offset;fd_i=fd_i->next) {
if (!last_fd || last_fd->offset!=fd_i->offset){
dfpos += fd_i->len;
}
last_fd=fd_i;
}
if(fd_i){
/* new fragment overlaps existing fragment */
if(fd_i->len!=fd->len){
/*
* They have different lengths; this
* is definitely a conflict.
*/
fd->flags |= FD_OVERLAPCONFLICT;
fd_head->flags |= FD_OVERLAPCONFLICT;
LINK_FRAG(fd_head,fd);
return TRUE;
}
g_assert(fd_head->len >= dfpos + fd->len);
if ( memcmp(fd_head->data+dfpos,
tvb_get_ptr(tvb,offset,fd->len),fd->len) ){
/*
* They have the same length, but the
* data isn't the same.
*/
fd->flags |= FD_OVERLAPCONFLICT;
fd_head->flags |= FD_OVERLAPCONFLICT;
LINK_FRAG(fd_head,fd);
return TRUE;
}
/* it was just an overlap, link it and return */
LINK_FRAG(fd_head,fd);
return TRUE;
} else {
/*
* New fragment doesn't overlap an existing
* fragment - there was presumably a gap in
* the sequence number space.
*
* XXX - what should we do here? Is it always
* the case that there are no gaps, or are there
* protcols using sequence numbers where there
* can be gaps?
*
* If the former, the check below for having
* received all the fragments should check for
* holes in the sequence number space and for the
* first sequence number being 0. If we do that,
* the only way we can get here is if this fragment
* is past the end of the sequence number space -
* but the check for "fd->offset > fd_head->datalen"
* would have caught that above, so it can't happen.
*
* If the latter, we don't have a good way of
* knowing whether reassembly is complete if we
* get packet out of order such that the "last"
* fragment doesn't show up last - but, unless
* in-order reliable delivery of fragments is
* guaranteed, an implementation of the protocol
* has no way of knowing whether reassembly is
* complete, either.
*
* For now, we just link the fragment in and
* return.
*/
LINK_FRAG(fd_head,fd);
return TRUE;
}
}
/* If we have reached this point, the packet is not defragmented yet.
* Save all payload in a buffer until we can defragment.
* XXX - what if we didn't capture the entire fragment due
* to a too-short snapshot length?
*/
fd->data = g_malloc(fd->len);
tvb_memcpy(tvb, fd->data, offset, fd->len);
LINK_FRAG(fd_head,fd);
if( !(fd_head->datalen) ){
/* if we dont know the sequence number of the last fragment,
* there are definitely still missing packets. Cheaper than
* the check below.
*/
return FALSE;
}
/* check if we have received the entire fragment
* this is easy since the list is sorted and the head is faked.
*/
max = 0;
for(fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
if ( fd_i->offset==max ){
max++;
}
}
/* max will now be datalen+1 if all fragments have been seen */
if (max <= fd_head->datalen) {
/* we have not received all packets yet */
return FALSE;
}
if (max > (fd_head->datalen+1)) {
/* oops, too long fragment detected */
fd->flags |= FD_TOOLONGFRAGMENT;
fd_head->flags |= FD_TOOLONGFRAGMENT;
}
/* we have received an entire packet, defragment it and
* free all fragments
*/
size=0;
last_fd=NULL;
for(fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
if(!last_fd || last_fd->offset!=fd_i->offset){
size+=fd_i->len;
}
last_fd=fd_i;
}
fd_head->data = g_malloc(size);
fd_head->len = size; /* record size for caller */
/* add all data fragments */
last_fd=NULL;
for (dfpos=0,fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
if (fd_i->len) {
if(!last_fd || last_fd->offset!=fd_i->offset){
memcpy(fd_head->data+dfpos,fd_i->data,fd_i->len);
dfpos += fd_i->len;
} else {
/* duplicate/retransmission/overlap */
fd_i->flags |= FD_OVERLAP;
fd_head->flags |= FD_OVERLAP;
if( (last_fd->len!=fd_i->datalen)
|| memcmp(last_fd->data, fd_i->data, last_fd->len) ){
fd->flags |= FD_OVERLAPCONFLICT;
fd_head->flags |= FD_OVERLAPCONFLICT;
}
}
last_fd=fd_i;
}
}
/* we have defragmented the pdu, now free all fragments*/
for (fd_i=fd_head->next;fd_i;fd_i=fd_i->next) {
if(fd_i->data){
g_free(fd_i->data);
fd_i->data=NULL;
}
}
/* mark this packet as defragmented.
allows us to skip any trailing fragments */
fd_head->flags |= FD_DEFRAGMENTED;
fd_head->reassembled_in=pinfo->fd->num;
return TRUE;
}
/*
* This function adds a new fragment to the fragment hash table.
* If this is the first fragment seen for this datagram, a new entry
* is created in the hash table, otherwise this fragment is just added
* to the linked list of fragments for this packet.
*
* Returns a pointer to the head of the fragment data list if we have all the
* fragments, NULL otherwise.
*
* This function assumes frag_number being a block sequence number.
* The bsn for the first block is 0.
*/
fragment_data *
fragment_add_seq(tvbuff_t *tvb, int offset, packet_info *pinfo, guint32 id,
GHashTable *fragment_table, guint32 frag_number,
guint32 frag_data_len, gboolean more_frags)
{
fragment_key key, *new_key;
fragment_data *fd_head;
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
fd_head = g_hash_table_lookup(fragment_table, &key);
/* have we already seen this frame ?*/
if (pinfo->fd->flags.visited) {
if (fd_head != NULL && fd_head->flags & FD_DEFRAGMENTED) {
return fd_head;
} else {
return NULL;
}
}
if (fd_head==NULL){
/* not found, this must be the first snooped fragment for this
* packet. Create list-head.
*/
fd_head=g_mem_chunk_alloc(fragment_data_chunk);
/* head/first structure in list only holds no other data than
* 'datalen' then we don't have to change the head of the list
* even if we want to keep it sorted
*/
fd_head->next=NULL;
fd_head->datalen=0;
fd_head->offset=0;
fd_head->len=0;
fd_head->flags=FD_BLOCKSEQUENCE;
fd_head->data=NULL;
fd_head->reassembled_in=0;
/*
* We're going to use the key to insert the fragment,
* so allocate a structure for it, and copy the
* addresses, allocating new buffers for the address
* data.
*/
new_key = g_mem_chunk_alloc(fragment_key_chunk);
COPY_ADDRESS(&new_key->src, &key.src);
COPY_ADDRESS(&new_key->dst, &key.dst);
new_key->id = key.id;
g_hash_table_insert(fragment_table, new_key, fd_head);
}
if (fragment_add_seq_work(fd_head, tvb, offset, pinfo,
frag_number, frag_data_len, more_frags)) {
/*
* Reassembly is complete.
*/
return fd_head;
} else {
/*
* Reassembly isn't complete.
*/
return NULL;
}
}
/*
* This does the work for "fragment_add_seq_check()" and
* "fragment_add_seq_next()".
*
* This function assumes frag_number being a block sequence number.
* The bsn for the first block is 0.
*
* If "no_frag_number" is TRUE, it uses the next expected fragment number
* as the fragment number if there is a reassembly in progress, otherwise
* it uses 0.
*
* If "no_frag_number" is FALSE, it uses the "frag_number" argument as
* the fragment number.
*
* If this is the first fragment seen for this datagram, a new
* "fragment_data" structure is allocated to refer to the reassembled,
* packet, and:
*
* if "more_frags" is false, the structure is not added to
* the hash table, and not given any fragments to refer to,
* but is just returned;
*
* if "more_frags" is true, this fragment is added to the linked
* list of fragments for this packet, and the "fragment_data"
* structure is put into the hash table.
*
* Otherwise, this fragment is just added to the linked list of fragments
* for this packet.
*
* Returns a pointer to the head of the fragment data list, and removes
* that from the fragment hash table if necessary and adds it to the
* table of reassembled fragments, if we have all the fragments or if
* this is the only fragment and "more_frags" is false, returns NULL
* otherwise.
*/
fragment_data *
fragment_add_seq_check_work(tvbuff_t *tvb, int offset, packet_info *pinfo,
guint32 id, GHashTable *fragment_table,
GHashTable *reassembled_table, guint32 frag_number,
guint32 frag_data_len, gboolean more_frags,
gboolean no_frag_number)
{
reassembled_key reass_key;
fragment_key key, *new_key, *old_key;
gpointer orig_key, value;
fragment_data *fd_head, *fd;
/*
* Have we already seen this frame?
* If so, look for it in the table of reassembled packets.
*/
if (pinfo->fd->flags.visited) {
reass_key.frame = pinfo->fd->num;
reass_key.id = id;
return g_hash_table_lookup(reassembled_table, &reass_key);
}
/* create key to search hash with */
key.src = pinfo->src;
key.dst = pinfo->dst;
key.id = id;
if (!g_hash_table_lookup_extended(fragment_table, &key,
&orig_key, &value)) {
/* not found, this must be the first snooped fragment for this
* packet. Create list-head.
*/
fd_head=g_mem_chunk_alloc(fragment_data_chunk);
/* head/first structure in list only holds no other data than
* 'datalen' then we don't have to change the head of the list
* even if we want to keep it sorted
*/
fd_head->next=NULL;
fd_head->datalen=0;
fd_head->offset=0;
fd_head->len=0;
fd_head->flags=FD_BLOCKSEQUENCE;
fd_head->data=NULL;
fd_head->reassembled_in=0;
if (!more_frags) {
/*
* This is the last snooped fragment for this
* packet as well; that means it's the only
* fragment. Just add it to the table of
* reassembled packets, and return it.
*/
fragment_reassembled(fd_head, pinfo,
reassembled_table, id);
return fd_head;
}
/*
* We're going to use the key to insert the fragment,
* so allocate a structure for it, and copy the
* addresses, allocating new buffers for the address
* data.
*/
new_key = g_mem_chunk_alloc(fragment_key_chunk);
COPY_ADDRESS(&new_key->src, &key.src);
COPY_ADDRESS(&new_key->dst, &key.dst);
new_key->id = key.id;
g_hash_table_insert(fragment_table, new_key, fd_head);
orig_key = new_key; /* for unhashing it later */
/*
* If we weren't given an initial fragment number,
* make it 0.
*/
if (no_frag_number)
frag_number = 0;
} else {
/*
* We found it.
*/
fd_head = value;
/*
* If we weren't given an initial fragment number,
* use the next expected fragment number as the fragment
* number for this fragment.
*/
if (no_frag_number) {
for (fd = fd_head; fd != NULL; fd = fd->next) {
if (fd->next == NULL)
frag_number = fd->offset + 1;
}
}
}
/*
* If we don't have all the data that is in this fragment,
* then we can't, and don't, do reassembly on it.
*
* If it's the first frame, handle it as an unfragmented packet.
* Otherwise, just handle it as a fragment.
*
* If "more_frags" isn't set, we get rid of the entry in the
* hash table for this reassembly, as we don't need it any more.
*/
if (!tvb_bytes_exist(tvb, offset, frag_data_len)) {
if (!more_frags) {
/*
* Remove this from the table of in-progress
* reassemblies, and free up any memory used for
* it in that table.
*/
old_key = orig_key;
fragment_unhash(fragment_table, old_key);
}
return frag_number == 0 ? fd_head : NULL;
}
if (fragment_add_seq_work(fd_head, tvb, offset, pinfo,
frag_number, frag_data_len, more_frags)) {
/*
* Reassembly is complete.
* Remove this from the table of in-progress
* reassemblies, add it to the table of
* reassembled packets, and return it.
*/
/*
* Remove this from the table of in-progress reassemblies,
* and free up any memory used for it in that table.
*/
old_key = orig_key;
fragment_unhash(fragment_table, old_key);
/*
* Add this item to the table of reassembled packets.
*/
fragment_reassembled(fd_head, pinfo, reassembled_table, id);
return fd_head;
} else {
/*
* Reassembly isn't complete.
*/
return NULL;
}
}
fragment_data *
fragment_add_seq_check(tvbuff_t *tvb, int offset, packet_info *pinfo,
guint32 id, GHashTable *fragment_table,
GHashTable *reassembled_table, guint32 frag_number,
guint32 frag_data_len, gboolean more_frags)
{
return fragment_add_seq_check_work(tvb, offset, pinfo, id,
fragment_table, reassembled_table, frag_number, frag_data_len,
more_frags, FALSE);
}
fragment_data *
fragment_add_seq_next(tvbuff_t *tvb, int offset, packet_info *pinfo,
guint32 id, GHashTable *fragment_table,
GHashTable *reassembled_table, guint32 frag_data_len,
gboolean more_frags)
{
return fragment_add_seq_check_work(tvb, offset, pinfo, id,
fragment_table, reassembled_table, 0, frag_data_len,
more_frags, TRUE);
}
/*
* Process reassembled data; if we're on the frame in which the data
* was reassembled, put the fragment information into the protocol
* tree, and construct a tvbuff with the reassembled data, otherwise
* just put a "reassembled in" item into the protocol tree.
*/
tvbuff_t *
process_reassembled_data(tvbuff_t *tvb, packet_info *pinfo, char *name,
fragment_data *fd_head, const fragment_items *fit,
gboolean *update_col_infop, proto_tree *tree)
{
tvbuff_t *next_tvb;
gboolean update_col_info;
if (pinfo->fd->num == fd_head->reassembled_in) {
/*
* OK, we have the complete reassembled payload.
* Allocate a new tvbuff, referring to the reassembled
* payload.
*/
if (fd_head->flags & FD_BLOCKSEQUENCE) {
next_tvb = tvb_new_real_data(fd_head->data,
fd_head->len, fd_head->len);
} else {
next_tvb = tvb_new_real_data(fd_head->data,
fd_head->datalen, fd_head->datalen);
}
/*
* Add the tvbuff to the list of tvbuffs to which
* the tvbuff we were handed refers, so it'll get
* cleaned up when that tvbuff is cleaned up.
*/
tvb_set_child_real_data_tvbuff(tvb, next_tvb);
/* Add the defragmented data to the data source list. */
add_new_data_source(pinfo, next_tvb, name);
/* show all fragments */
if (fd_head->flags & FD_BLOCKSEQUENCE) {
update_col_info = !show_fragment_seq_tree(fd_head,
fit, tree, pinfo, next_tvb);
} else {
update_col_info = !show_fragment_tree(fd_head,
fit, tree, pinfo, next_tvb);
}
if (update_col_infop != NULL)
*update_col_infop = update_col_info;
} else {
/* We don't have the complete reassembled payload. */
next_tvb = NULL;
/*
* If there's a field to use for the number of
* the frame in which the packet was reassembled,
* add it to the protocol tree.
*/
if (fit->hf_reassembled_in != NULL) {
proto_tree_add_uint(tree,
*(fit->hf_reassembled_in), tvb,
0, 0, fd_head->reassembled_in);
}
}
return next_tvb;
}
/*
* Show a single fragment in a fragment subtree.
*/
static void
show_fragment(fragment_data *fd, int offset, const fragment_items *fit,
proto_tree *ft, tvbuff_t *tvb)
{
if (fd->flags & (FD_OVERLAP|FD_OVERLAPCONFLICT
|FD_MULTIPLETAILS|FD_TOOLONGFRAGMENT) ) {
/* this fragment has some flags set, create a subtree
* for it and display the flags.
*/
proto_tree *fet=NULL;
proto_item *fei=NULL;
int hf;
if (fd->flags & (FD_OVERLAPCONFLICT
|FD_MULTIPLETAILS|FD_TOOLONGFRAGMENT) ) {
hf = *(fit->hf_fragment_error);
} else {
hf = *(fit->hf_fragment);
}
fei = proto_tree_add_uint_format(ft, hf,
tvb, offset, fd->len,
fd->frame,
"Frame:%u payload:%u-%u",
fd->frame,
offset,
offset+fd->len-1);
fet = proto_item_add_subtree(fei, *(fit->ett_fragment));
if (fd->flags&FD_OVERLAP) {
proto_tree_add_boolean(fet,
*(fit->hf_fragment_overlap),
tvb, 0, 0,
TRUE);
}
if (fd->flags&FD_OVERLAPCONFLICT) {
proto_tree_add_boolean(fet,
*(fit->hf_fragment_overlap_conflict),
tvb, 0, 0,
TRUE);
}
if (fd->flags&FD_MULTIPLETAILS) {
proto_tree_add_boolean(fet,
*(fit->hf_fragment_multiple_tails),
tvb, 0, 0,
TRUE);
}
if (fd->flags&FD_TOOLONGFRAGMENT) {
proto_tree_add_boolean(fet,
*(fit->hf_fragment_too_long_fragment),
tvb, 0, 0,
TRUE);
}
} else {
/* nothing of interest for this fragment */
proto_tree_add_uint_format(ft, *(fit->hf_fragment),
tvb, offset, fd->len,
fd->frame,
"Frame:%u payload:%u-%u",
fd->frame,
offset,
offset+fd->len-1
);
}
}
static gboolean
show_fragment_errs_in_col(fragment_data *fd_head, const fragment_items *fit,
packet_info *pinfo)
{
if (fd_head->flags & (FD_OVERLAPCONFLICT
|FD_MULTIPLETAILS|FD_TOOLONGFRAGMENT) ) {
if (check_col(pinfo->cinfo, COL_INFO)) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"[Illegal %s]", fit->tag);
return TRUE;
}
}
return FALSE;
}
/* This function will build the fragment subtree; it's for fragments
reassembled with "fragment_add()".
It will return TRUE if there were fragmentation errors
or FALSE if fragmentation was ok.
*/
gboolean
show_fragment_tree(fragment_data *fd_head, const fragment_items *fit,
proto_tree *tree, packet_info *pinfo, tvbuff_t *tvb)
{
fragment_data *fd;
proto_tree *ft;
proto_item *fi;
/* It's not fragmented. */
pinfo->fragmented = FALSE;
fi = proto_tree_add_item(tree, *(fit->hf_fragments),
tvb, 0, -1, FALSE);
ft = proto_item_add_subtree(fi, *(fit->ett_fragments));
for (fd = fd_head->next; fd != NULL; fd = fd->next)
show_fragment(fd, fd->offset, fit, ft, tvb);
return show_fragment_errs_in_col(fd_head, fit, pinfo);
}
/* This function will build the fragment subtree; it's for fragments
reassembled with "fragment_add_seq()" or "fragment_add_seq_check()".
It will return TRUE if there were fragmentation errors
or FALSE if fragmentation was ok.
*/
gboolean
show_fragment_seq_tree(fragment_data *fd_head, const fragment_items *fit,
proto_tree *tree, packet_info *pinfo, tvbuff_t *tvb)
{
guint32 offset, next_offset;
fragment_data *fd, *last_fd;
proto_tree *ft;
proto_item *fi;
/* It's not fragmented. */
pinfo->fragmented = FALSE;
fi = proto_tree_add_item(tree, *(fit->hf_fragments),
tvb, 0, -1, FALSE);
ft = proto_item_add_subtree(fi, *(fit->ett_fragments));
offset = 0;
next_offset = 0;
last_fd = NULL;
for (fd = fd_head->next; fd != NULL; fd = fd->next){
if (last_fd == NULL || last_fd->offset != fd->offset) {
offset = next_offset;
next_offset += fd->len;
}
last_fd = fd;
show_fragment(fd, offset, fit, ft, tvb);
}
return show_fragment_errs_in_col(fd_head, fit, pinfo);
}
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