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From Matt P: 

CCSDS packets may reside within an 802.3 packet.  This patch provides a way for
the CCSDS dissector to be called from the 802.3 dissector.

svn path=/trunk/; revision=27257
This commit is contained in:
Jaap Keuter 2009-01-18 12:08:56 +00:00
parent fb9e53c635
commit 17df7f823e
3 changed files with 88 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
epan/dissectors/packet-ccsds.c
View File

@ -236,6 +236,7 @@ proto_register_ccsds(void)
/* Required function calls to register the header fields and subtrees used */
proto_register_field_array(proto_ccsds, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_dissector("ccsds", dissect_ccsds, proto_ccsds);
}

83
epan/dissectors/packet-eth.c
View File

@ -41,6 +41,11 @@
/* Interpret packets as FW1 monitor file packets if they look as if they are */
static gboolean eth_interpret_as_fw1_monitor = FALSE;
/* Preference settings defining conditions for which the CCSDS dissector is called */
static gboolean ccsds_heuristic_length = FALSE;
static gboolean ccsds_heuristic_version = FALSE;
static gboolean ccsds_heuristic_header = FALSE;
static gboolean ccsds_heuristic_bit = FALSE;
/* protocols and header fields */
static int proto_eth = -1;
@ -172,7 +177,7 @@ capture_eth(const guchar *pd, int offset, int len, packet_counts *ld)
}
}
static gboolean chek_is_802_2(tvbuff_t *tvb);
static gboolean check_is_802_2(tvbuff_t *tvb);
static void
dissect_eth_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree,
@ -256,7 +261,7 @@ dissect_eth_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree,
*/
if (ehdr->type <= IEEE_802_3_MAX_LEN && ehdr->type != ETHERTYPE_UNK) {
is_802_2 = chek_is_802_2(tvb);
is_802_2 = check_is_802_2(tvb);
if (check_col(pinfo->cinfo, COL_INFO)) {
col_add_fstr(pinfo->cinfo, COL_INFO, "IEEE 802.3 Ethernet %s",
@ -341,7 +346,7 @@ dissect_eth_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree,
}
/* -------------- */
static gboolean chek_is_802_2(tvbuff_t *tvb)
static gboolean check_is_802_2(tvbuff_t *tvb)
{
volatile gboolean is_802_2;
@ -350,12 +355,48 @@ static gboolean chek_is_802_2(tvbuff_t *tvb)
/* Is there an 802.2 layer? I can tell by looking at the first 2
bytes after the 802.3 header. If they are 0xffff, then what
follows the 802.3 header is an IPX payload, meaning no 802.2.
(IPX/SPX is they only thing that can be contained inside a
straight 802.3 packet). A non-0xffff value means that there's an
802.2 layer inside the 802.3 layer */
A non-0xffff value means that there's an 802.2 layer or CCSDS
layer inside the 802.3 layer */
TRY {
if (tvb_get_ntohs(tvb, 14) == 0xffff) {
if (tvb_get_ntohs(tvb, 14) == 0xffff) {
is_802_2 = FALSE;
}
/* Is this a CCSDS payload instead of an 802.2 (LLC)?
Check the conditions enabled by the user for CCSDS presence */
else if (ccsds_heuristic_length || ccsds_heuristic_version ||
ccsds_heuristic_header || ccsds_heuristic_bit) {
gboolean CCSDS_len = TRUE;
gboolean CCSDS_ver = TRUE;
gboolean CCSDS_head = TRUE;
gboolean CCSDS_bit = TRUE;
/* See if the reported payload size matches the
size contained in the CCSDS header. */
if (ccsds_heuristic_length) {
/* Get payload length */
gint size = tvb_reported_length(tvb) - 14;
/* Check if payload is large enough to contain CCSDS header with
packet length info. */
if (size >= 6) {
/* Get CCSDS packet length contained in CCSDS header. */
gint size2 = 7 + tvb_get_ntohs(tvb, 14 + 4);
if (size != size2)
CCSDS_len = FALSE;
}
}
/* Check if CCSDS Version number (first 3 bits of payload) is zero */
if ((ccsds_heuristic_version) && (tvb_get_bits8(tvb, 8*14, 3)!=0))
CCSDS_ver = FALSE;
/* Check if Secondary Header Flag (4th bit of payload) is set to one. */
if ((ccsds_heuristic_header) && (tvb_get_bits8(tvb, 8*14 + 4, 1)!=1))
CCSDS_head = FALSE;
/* Check if spare bit (1st bit of 7th word of payload) is zero. */
if ((ccsds_heuristic_bit) && (tvb_get_bits8(tvb, 8*14 + 16*6, 1)!=0))
CCSDS_bit = FALSE;
/* If all the conditions are true, don't interpret payload as an 802.2 (LLC).
* Additional check in packet-802.3.c will distinguish between
* IPX and CCSDS packets*/
if (CCSDS_len && CCSDS_ver && CCSDS_head && CCSDS_bit)
is_802_2 = FALSE;
}
}
@ -543,6 +584,32 @@ proto_register_eth(void)
"Whether packets should be interpreted as coming from CheckPoint FireWall-1 monitor file if they look as if they do",
&eth_interpret_as_fw1_monitor);
prefs_register_static_text_preference(eth_module, "ccsds_heuristic",
"These are the conditions to match a payload against in order to determine\n"
"if this is a CCSDS packet within an 802.3 packet. If none is checked a packet\n"
"is never considered to be a CCSDS packet.",
"Describe the conditions that must be true for the CCSDS dissector to be called");
prefs_register_bool_preference(eth_module, "ccsds_heuristic_length",
"CCSDS Length in header matches payload size",
"Set the condition that must be true for the CCSDS dissector to be called",
&ccsds_heuristic_length);
prefs_register_bool_preference(eth_module, "ccsds_heuristic_version",
"CCSDS Version # is zero",
"Set the condition that must be true for the CCSDS dissector to be called",
&ccsds_heuristic_version);
prefs_register_bool_preference(eth_module, "ccsds_heuristic_header",
"CCSDS Secondary Header Flag is set",
"Set the condition that must be true for the CCSDS dissector to be called",
&ccsds_heuristic_header);
prefs_register_bool_preference(eth_module, "ccsds_heuristic_bit",
"CCSDS Spare bit is cleared",
"Set the condition that must be true for the CCSDS dissector to be called",
&ccsds_heuristic_bit);
register_dissector("eth_withoutfcs", dissect_eth_withoutfcs, proto_eth);
register_dissector("eth_withfcs", dissect_eth_withfcs, proto_eth);
register_dissector("eth", dissect_eth_maybefcs, proto_eth);

15
epan/dissectors/packet-ieee8023.c
View File

@ -35,6 +35,7 @@
static dissector_handle_t ipx_handle;
static dissector_handle_t llc_handle;
static dissector_handle_t ccsds_handle;
void
dissect_802_3(volatile int length, gboolean is_802_2, tvbuff_t *tvb,
@ -98,8 +99,15 @@ dissect_802_3(volatile int length, gboolean is_802_2, tvbuff_t *tvb,
TRY {
if (is_802_2)
call_dissector(llc_handle, next_tvb, pinfo, tree);
else
call_dissector(ipx_handle, next_tvb, pinfo, tree);
else {
/* Check if first three bits of payload are 0x7.
If so, then payload is IPX. If not, then it's CCSDS.
Refer to packet-eth.c for setting of is_802_2 variable. */
if (tvb_get_bits8(next_tvb, 0, 3) == 7)
call_dissector(ipx_handle, next_tvb, pinfo, tree);
else
call_dissector(ccsds_handle, next_tvb, pinfo, tree);
}
}
CATCH(BoundsError) {
/* Somebody threw BoundsError, which means that dissecting the payload
@ -126,8 +134,9 @@ void
proto_reg_handoff_ieee802_3(void)
{
/*
* Get handles for the IPX and LLC dissectors.
* Get handles for the subdissectors.
*/
ipx_handle = find_dissector("ipx");
llc_handle = find_dissector("llc");
ccsds_handle = find_dissector("ccsds");
}