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Fix checksum handling (using val_to_str() on a Boolean is overkill, and 

calc_checksum() doesn't return a Boolean, it returns a cksum_status_t,
which has more values than just "checksum OK" and "checksum not OK",
such as "not enough data available to check the checksum).

Fix typoes (Transport Protocol Data Unit is TPDU/tpdu, not TDPU/tdpu).

svn path=/trunk/; revision=46051
This commit is contained in:
Guy Harris 2012-11-17 09:37:04 +00:00
parent fa031995da
commit cbd58e5115
1 changed files with 57 additions and 36 deletions
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93
epan/dissectors/packet-ositp.c
View File

@ -269,13 +269,6 @@ static const value_string tp_vpart_type_vals[] = {
{ 0, NULL }
};
static const value_string tp_vpart_checksum_vals[] = {
{ FALSE, "incorrect" },
{ TRUE, "correct" },
{ 0, NULL }
};
static int hf_cotp_vp_src_tsap = -1;
static int hf_cotp_vp_dst_tsap = -1;
static int hf_cotp_vp_src_tsap_bytes = -1;
@ -393,15 +386,16 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset,
guint32 t1, t2, t3, t4;
guint32 offset_iso8073_checksum = 0;
gint32 i = 0;
guint16 tdpu_length = 0;
guint16 tpdu_length = 0;
guint8 tmp_code = 0;
guint tmp_len = 0;
guint checksum_ok = 0;
cksum_status_t cksum_status;
gboolean checksum_ok = FALSE;
guint32 pref_max_tpdu_size;
proto_item *hidden_item;
/* TDPU length needed for ATN checksum calculations */
tdpu_length = offset + vp_length + tvb_length_remaining(tvb, offset + vp_length);
/* TPDU length needed for ATN checksum calculations */
tpdu_length = offset + vp_length + tvb_length_remaining(tvb, offset + vp_length);
while (vp_length != 0) {
code = tvb_get_guint8(tvb, offset);
@ -424,7 +418,7 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset,
case VP_ATN_EC_16 : /* ATN */
if (cotp_decode_atn) {
/* if an alternate OSI checksum is present in the currently unprocessed VP section to the checksum algorithm has to know */
/* this may be the case for backward compatible CR TDPU */
/* this may be the case for backward compatible CR TPDU */
if(!offset_iso8073_checksum){
/* search following parameters in VP part for ISO checksum */
for( i = ( offset + length ); i < vp_length; ){
@ -436,11 +430,11 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset,
}
i += tmp_len; }
}
checksum_ok = check_atn_ec_16(tvb, tdpu_length, offset, offset_iso8073_checksum, clnp_pt_len, (guint8 *) &clnp_pt_buffer);
checksum_ok = check_atn_ec_16(tvb, tpdu_length, offset, offset_iso8073_checksum, clnp_pt_len, (guint8 *) &clnp_pt_buffer);
proto_tree_add_text(tree, tvb, offset, length,
"ATN extended checksum : 0x%04x (%s)",
tvb_get_ntohs(tvb, offset),
val_to_str(checksum_ok, tp_vpart_checksum_vals, "?"));
checksum_ok ? "correct" : "incorrect");
}else {
proto_tree_add_text(tree, tvb, offset, length,"Parameter value: <not shown>");
}
@ -451,7 +445,7 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset,
case VP_ATN_EC_32 : /* ATN */
if (cotp_decode_atn) {
/* if an alternate OSI checksum is present in the currently unprocessed VP section the checksum algorithm has to know */
/* this may be the case for backward compatible CR TDPU */
/* this may be the case for backward compatible CR TPDU */
if(!offset_iso8073_checksum){
/* search following parameters in VP part for ISO checksum */
for( i = ( offset + length ); i < vp_length; ){
@ -462,11 +456,11 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset,
break;}
i += tmp_len; }
}
checksum_ok = check_atn_ec_32(tvb, tdpu_length, offset, offset_iso8073_checksum, clnp_pt_len, (guint8 *) &clnp_pt_buffer);
checksum_ok = check_atn_ec_32(tvb, tpdu_length, offset, offset_iso8073_checksum, clnp_pt_len, (guint8 *) &clnp_pt_buffer);
proto_tree_add_text(tree, tvb, offset, length,
"ATN extended checksum : 0x%08x (%s)",
tvb_get_ntohl(tvb, offset),
val_to_str(checksum_ok, tp_vpart_checksum_vals, "?"));
checksum_ok ? "correct" : "incorrect");
}else {
proto_tree_add_text(tree, tvb, offset, length,"Parameter value: <not shown>");
}
@ -686,9 +680,36 @@ static gboolean ositp_decode_var_part(tvbuff_t *tvb, int offset,
case VP_CHECKSUM:
offset_iso8073_checksum = offset; /* save ISO 8073 checksum offset for ATN extended checksum calculation */
checksum_ok = calc_checksum(tvb, 0, tdpu_length, tvb_get_ntohs(tvb, offset));
proto_tree_add_text(tree, tvb, offset, length,
"Checksum: 0x%04x (%s)", tvb_get_ntohs(tvb, offset),val_to_str( (checksum_ok == CKSUM_OK) ? TRUE : FALSE , tp_vpart_checksum_vals, "?"));
cksum_status = calc_checksum(tvb, 0, tpdu_length, tvb_get_ntohs(tvb, offset));
switch (cksum_status) {
default:
/*
* No checksum present, or not enough of the packet present to
* checksum it.
*/
proto_tree_add_text(tree, tvb, offset, length,
"Checksum: 0x%04x", tvb_get_ntohs(tvb, offset));
break;
case CKSUM_OK:
/*
* Checksum is correct.
*/
proto_tree_add_text(tree, tvb, offset, length,
"Checksum: 0x%04x (correct)",
tvb_get_ntohs(tvb, offset));
break;
case CKSUM_NOT_OK:
/*
* Checksum is not correct.
*/
proto_tree_add_text(tree, tvb, offset, length,
"Checksum: 0x%04x (incorrect)",
tvb_get_ntohs(tvb, offset));
break;
}
offset += length;
vp_length -= length;
break;
@ -895,7 +916,7 @@ static int ositp_decode_DT(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
/* note: in the ATN the user is up to chose between 3 different checksums: */
/* standard OSI, 2 or 4 octet extended checksum. */
/* The differences for DT are that the TDPU headers may be enlarged by 2 octets */
/* The differences for DT are that the TPDU headers may be enlarged by 2 octets */
/* and that checksum related option codes and option lengths are different. */
/* to not mess up the original OSI dissector LI checking was implemented separately. */
if (!cotp_decode_atn) { /* non ATN, plain OSI*/
@ -973,13 +994,13 @@ static int ositp_decode_DT(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
return -1;
} /* li */
} else {
/* check ATN class4 TDPU's here */
/* check ATN class4 TPDU's here */
/* check packet length indicators of DaTa(DT) TDPU */
/* check packet length indicators of DaTa(DT) TPDU */
/* note: use of checksum depends on the selected RER */
/* (high:non-use medium:16-bit OSI/16-bit ext.ATN low:32-bit ext. ATN) */
/* note: sole use of TP4 class in the ATN */
/* note: normal/extended TDPU numbering is negociable */
/* note: normal/extended TPDU numbering is negociable */
switch (li) {
case LI_NORMAL_DT_WITHOUT_CHECKSUM :
@ -1227,7 +1248,7 @@ static int ositp_decode_ED(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
/* note: in the ATN the user is up to chose between 3 different checksums: */
/* standard OSI, 2 or 4 octet extended checksum. */
/* The differences for ED (as for DT) are that the TDPU headers may be enlarged by 2 octets */
/* The differences for ED (as for DT) are that the TPDU headers may be enlarged by 2 octets */
/* and that checksum related option codes and option lengths are different. */
/* to not mess up the original OSI dissector LI checking was implemented separately. */
/* note: this could not be tested, because no sample was avail for expedited data */
@ -1272,11 +1293,11 @@ static int ositp_decode_ED(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
} /* li */
}else {
/* check packet length indicators of ATN Expedited Data (ED) TDPU */
/* check packet length indicators of ATN Expedited Data (ED) TPDU */
/* note: use of checksum depends on the selected RER */
/* (high:non-use medium:16-bit OSI/16-bit ext.ATN low:32-bit ext. ATN) */
/* note: sole use of TP4 class in the ATN */
/* note: normal/extended TDPU numbering is negociable */
/* note: normal/extended TPDU numbering is negociable */
switch (li) {
case LI_NORMAL_DT_WITHOUT_CHECKSUM :
tpdu_nr = tvb_get_guint8(tvb, offset + P_TPDU_NR_234);
@ -1424,7 +1445,7 @@ static int ositp_decode_RJ(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
/* note: in the ATN the user is up to chose between 3 different checksums: */
/* standard OSI, 2 or 4 octet extended checksum. */
/* The difference for RJ is that the TDPU header may be enlarged by 2 octets */
/* The difference for RJ is that the TPDU header may be enlarged by 2 octets */
/* for checksum parameters are not going to be checked here */
if (!cotp_decode_atn) { /* non ATN, plain OSI*/
switch(li) {
@ -1774,7 +1795,7 @@ static int ositp_decode_EA(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
guint16 dst_ref;
guint tpdu_nr;
/* Due to different checksums in the ATN the TDPU header sizes */
/* Due to different checksums in the ATN the TPDU header sizes */
/* as well as the checksum parameters may be different than plain OSI EA.*/
/* because these are heavily checked for EA these checks had to be re-implemented. */
/* note: this could not be tested, because no sample was avail for expedited data */
@ -1815,18 +1836,18 @@ static int ositp_decode_EA(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
} /* li */
}else { /* cotp_decode_atn */
/* check for ATN length: TDPU may be 2 octets longer due to checksum */
/* check for ATN length: TPDU may be 2 octets longer due to checksum */
if (li > LI_ATN_MAX_EA)
return -1;
switch (li) {
/* extended TDPU numbering EA with no checksum */
/* extended TPDU numbering EA with no checksum */
case LI_NORMAL_EA_WITHOUT_CHECKSUM :
tpdu_nr = tvb_get_guint8(tvb, offset + P_TPDU_NR_234);
is_extended = FALSE;
break;
/* normal TDPU numbering EA with 2 octets of OSI or ATN extended checksum */
/* normal TPDU numbering EA with 2 octets of OSI or ATN extended checksum */
case LI_NORMAL_EA_WITH_CHECKSUM :
/* check checksum parameter (in VP) parameter code octet */
if ((tvb_get_guint8(tvb, offset + P_VAR_PART_NDT) != VP_CHECKSUM) &&
@ -1842,7 +1863,7 @@ static int ositp_decode_EA(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
tpdu_nr = tvb_get_guint8(tvb, offset + P_TPDU_NR_234);
is_extended = FALSE;
break;
/* normal TDPU numbering EA with 4 octets of ATN extended checksum */
/* normal TPDU numbering EA with 4 octets of ATN extended checksum */
case LI_ATN_NORMAL_EA_WITH_CHECKSUM :
/* check checksum parameter (in VP) parameter code octet */
if (tvb_get_guint8(tvb, offset + P_VAR_PART_NDT) != VP_ATN_EC_32 )
@ -1857,13 +1878,13 @@ static int ositp_decode_EA(tvbuff_t *tvb, int offset, guint8 li, guint8 tpdu,
tpdu_nr = tvb_get_guint8(tvb, offset + P_TPDU_NR_234);
is_extended = FALSE;
break;
/* extended TDPU numbering EA with no checksum */
/* extended TPDU numbering EA with no checksum */
case LI_EXTENDED_EA_WITHOUT_CHECKSUM :
tpdu_nr = tvb_get_ntohl(tvb, offset + P_TPDU_NR_234);
is_extended = TRUE;
break;
/* extended TDPU numbering EA with 2 octets of OSI or ATN extended checksum */
/* extended TPDU numbering EA with 2 octets of OSI or ATN extended checksum */
case LI_EXTENDED_EA_WITH_CHECKSUM :
/* check checksum parameter (in VP) parameter code octet */
if ( (tvb_get_guint8(tvb, offset + P_VAR_PART_EDT) != VP_CHECKSUM ) &&
@ -2302,7 +2323,7 @@ void proto_register_cotp(void)
prefs_register_bool_preference(cotp_module, "decode_atn",
"Decode ATN TPDUs",
"Whether to decode OSI TDPUs with ATN (Aereonautical Telecommunications Network) extensions."
"Whether to decode OSI TPDUs with ATN (Aereonautical Telecommunications Network) extensions."
" To use this option, you must also enable \"Always try to decode NSDU as transport PDUs\" in the CLNP protocol settings.",
&cotp_decode_atn);