/* Code to actually dissect the packets */
static void
dissect_ccsds(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
int offset = 0;
proto_item *ccsds_packet;
proto_tree *ccsds_tree = NULL;
proto_item *primary_header = NULL;
proto_tree *primary_header_tree;
guint16 first_word;
guint32 coarse_time;
guint8 fine_time;
proto_item *secondary_header;
proto_tree *secondary_header_tree;
const char* time_string;
gint ccsds_length;
gint length = 0;
gint reported_length;
guint8 checkword_flag = 0;
gint counter = 0;
proto_item *item = NULL;
proto_tree *checkword_tree;
guint16 checkword_field = 0;
guint16 checkword_sum = 0;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CCSDS");
col_set_str(pinfo->cinfo, COL_INFO, "CCSDS Packet");
first_word=tvb_get_ntohs(tvb, 0);
col_add_fstr(pinfo->cinfo, COL_INFO, "APID %1$4d (0x%1$03X)", first_word&HDR_APID);
reported_length = tvb_reported_length_remaining(tvb, 0);
ccsds_length = tvb_get_ntohs(tvb, 4) + CCSDS_PRIMARY_HEADER_LENGTH + 1;
if (tree) {
/* Min length is size of headers, whereas max length is reported length.
* If the length field in the CCSDS header is outside of these bounds,
* use the value it violates. Otherwise, use the length field value.
*/
if (ccsds_length > reported_length)
length = reported_length;
else if (ccsds_length < CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH)
length = CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH;
else
length = ccsds_length;
ccsds_packet = proto_tree_add_item(tree, proto_ccsds, tvb, 0, length, ENC_NA);
ccsds_tree = proto_item_add_subtree(ccsds_packet, ett_ccsds);
/* build the ccsds primary header tree */
primary_header=proto_tree_add_text(ccsds_tree, tvb, offset, CCSDS_PRIMARY_HEADER_LENGTH, "Primary CCSDS Header");
primary_header_tree=proto_item_add_subtree(primary_header, ett_ccsds_primary_header);
proto_tree_add_uint(primary_header_tree, hf_ccsds_version, tvb, offset, 2, first_word);
proto_tree_add_uint(primary_header_tree, hf_ccsds_type, tvb, offset, 2, first_word);
proto_tree_add_boolean(primary_header_tree, hf_ccsds_secheader, tvb, offset, 2, first_word);
proto_tree_add_uint(primary_header_tree, hf_ccsds_apid, tvb, offset, 2, first_word);
offset += 2;
proto_tree_add_item(primary_header_tree, hf_ccsds_seqflag, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(primary_header_tree, hf_ccsds_seqnum, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
item = proto_tree_add_item(primary_header_tree, hf_ccsds_length, tvb, offset, 2, ENC_BIG_ENDIAN);
}
if (ccsds_length > reported_length) {
expert_add_info_format(pinfo, item, PI_MALFORMED, PI_ERROR,
"Length field value is greater than the packet seen on the wire");
}
if (tree) {
offset += 2;
proto_item_set_end(primary_header, tvb, offset);
/* build the ccsds secondary header tree */
if ( first_word & HDR_SECHDR )
{
secondary_header=proto_tree_add_text(ccsds_tree, tvb, offset, CCSDS_SECONDARY_HEADER_LENGTH, "Secondary CCSDS Header");
secondary_header_tree=proto_item_add_subtree(secondary_header, ett_ccsds_secondary_header);
/* command ccsds secondary header flags */
coarse_time=tvb_get_ntohl(tvb, offset);
proto_tree_add_item(secondary_header_tree, hf_ccsds_coarse_time, tvb, offset, 4, ENC_BIG_ENDIAN);
offset += 4;
fine_time=tvb_get_guint8(tvb, offset);
proto_tree_add_item(secondary_header_tree, hf_ccsds_fine_time, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
time_string = embedded_time_to_string ( coarse_time, fine_time );
proto_tree_add_text(secondary_header_tree, tvb, offset-5, 5, "%s = Embedded Time", time_string);
proto_tree_add_item(secondary_header_tree, hf_ccsds_timeid, tvb, offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_checkword_flag, tvb, offset, 1, ENC_BIG_ENDIAN);
/* Global Preference: how to handle checkword flag */
switch (global_dissect_checkword) {
case 0:
/* force checkword presence flag to be false */
checkword_flag = 0;
break;
case 1:
/* force checkword presence flag to be true */
checkword_flag = 1;
break;
default:
/* use value of checkword presence flag from header */
checkword_flag = (tvb_get_guint8(tvb, offset)&0x20) >> 5;
break;
}
/* payload specific ccsds secondary header flags */
if ( first_word & HDR_TYPE )
{
proto_tree_add_item(secondary_header_tree, hf_ccsds_zoe, tvb, offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_packet_type_unused, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
proto_tree_add_item(secondary_header_tree, hf_ccsds_vid, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(secondary_header_tree, hf_ccsds_dcc, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
}
/* core specific ccsds secondary header flags */
else
{
/* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare1, tvb, offset, 1, ENC_BIG_ENDIAN); */
proto_tree_add_item(secondary_header_tree, hf_ccsds_packet_type, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
/* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare2, tvb, offset, 2, ENC_BIG_ENDIAN); */
proto_tree_add_item(secondary_header_tree, hf_ccsds_element_id, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_cmd_data_packet, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_format_version_id, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_extended_format_id, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare3, tvb, offset, 1, ENC_BIG_ENDIAN); */
++offset;
proto_tree_add_item(secondary_header_tree, hf_ccsds_frame_id, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
}
/* finish the ccsds secondary header */
proto_item_set_end(secondary_header, tvb, offset);
}
/* If there wasn't a full packet, then don't allow a tree item for checkword. */
if (reported_length < ccsds_length || ccsds_length < CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH) {
/* Label CCSDS payload 'User Data' */
if (length > offset)
proto_tree_add_text(ccsds_tree, tvb, offset, length-offset, "User Data");
offset += length-offset;
if (checkword_flag == 1)
proto_tree_add_text(ccsds_tree, tvb, offset, 0, "Packet does not contain a Checkword");
}
/* Handle checkword according to CCSDS preference setting. */
else {
/* Label CCSDS payload 'User Data' */
proto_tree_add_text(ccsds_tree, tvb, offset, length-offset-2*checkword_flag, "User Data");
offset += length-offset-2*checkword_flag;
/* If checkword is present, calculate packet checksum (16-bit running sum) for comparison */
if (checkword_flag == 1) {
/* don't count the checkword as part of the checksum */
while (counter < ccsds_length-2) {
checkword_sum += tvb_get_ntohs(tvb, counter);
counter += 2;
}
checkword_field = tvb_get_ntohs(tvb, offset);
/* Report checkword status */
if (checkword_sum == checkword_field) {
item = proto_tree_add_uint_format(ccsds_tree, hf_ccsds_checkword, tvb, offset, 2, checkword_field,
"CCSDS checkword: 0x%04x [correct]", checkword_field);
checkword_tree = proto_item_add_subtree(item, ett_ccsds_checkword);
item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_good, tvb, offset, 2, TRUE);
PROTO_ITEM_SET_GENERATED(item);
item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_bad, tvb, offset, 2, FALSE);
PROTO_ITEM_SET_GENERATED(item);
} else {
item = proto_tree_add_uint_format(ccsds_tree, hf_ccsds_checkword, tvb, offset, 2, checkword_field,
"CCSDS checkword: 0x%04x [incorrect, should be 0x%04x]", checkword_field, checkword_sum);
checkword_tree = proto_item_add_subtree(item, ett_ccsds_checkword);
item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_good, tvb, offset, 2, FALSE);
PROTO_ITEM_SET_GENERATED(item);
item = proto_tree_add_boolean(checkword_tree, hf_ccsds_checkword_bad, tvb, offset, 2, TRUE);
PROTO_ITEM_SET_GENERATED(item);
}
offset += 2;
}
}
/* Give the data dissector any bytes past the CCSDS packet length */
/* (XXX: Not really OK under 'if (tree)' but will work; see packet-data.c */
call_dissector(data_handle, tvb_new_subset_remaining(tvb, offset), pinfo, tree);
} /* if(tree) */
/* Code to actually dissect the packets */
static void
dissect_ccsds(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
int offset = 0;
proto_item *ccsds_packet;
proto_tree *ccsds_tree;
proto_item *primary_header;
proto_tree *primary_header_tree;
guint16 first_word;
guint32 coarse_time;
guint8 fine_time;
proto_item *secondary_header;
proto_tree *secondary_header_tree;
const char *time_string;
gint ccsds_length;
gint length = 0;
gint reported_length;
guint8 checkword_flag = 0;
gint counter = 0;
proto_item *item, *checkword_item = NULL;
proto_tree *checkword_tree;
guint16 checkword_field = 0;
guint16 checkword_sum = 0;
tvbuff_t *next_tvb;
static const int * header_flags[] = {
&hf_ccsds_version,
&hf_ccsds_type,
&hf_ccsds_secheader,
&hf_ccsds_apid,
NULL
};
col_set_str(pinfo->cinfo, COL_PROTOCOL, "CCSDS");
col_set_str(pinfo->cinfo, COL_INFO, "CCSDS Packet");
first_word = tvb_get_ntohs(tvb, 0);
col_add_fstr(pinfo->cinfo, COL_INFO, "APID %4d (0x%03X)", first_word&HDR_APID, first_word&HDR_APID);
reported_length = tvb_reported_length_remaining(tvb, 0);
ccsds_length = tvb_get_ntohs(tvb, 4) + CCSDS_PRIMARY_HEADER_LENGTH + 1;
/* Min length is size of headers, whereas max length is reported length.
* If the length field in the CCSDS header is outside of these bounds,
* use the value it violates. Otherwise, use the length field value.
*/
if (ccsds_length > reported_length)
length = reported_length;
else if (ccsds_length < CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH)
length = CCSDS_PRIMARY_HEADER_LENGTH + CCSDS_SECONDARY_HEADER_LENGTH;
else
length = ccsds_length;
ccsds_packet = proto_tree_add_item(tree, proto_ccsds, tvb, 0, length, ENC_NA);
ccsds_tree = proto_item_add_subtree(ccsds_packet, ett_ccsds);
/* build the ccsds primary header tree */
primary_header_tree = proto_tree_add_subtree(ccsds_tree, tvb, offset, CCSDS_PRIMARY_HEADER_LENGTH,
ett_ccsds_primary_header, &primary_header, "Primary CCSDS Header");
proto_tree_add_bitmask(primary_header_tree, tvb, offset, hf_ccsds_header_flags,
ett_ccsds_primary_header_flags, header_flags, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(primary_header_tree, hf_ccsds_seqflag, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(primary_header_tree, hf_ccsds_seqnum, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
item = proto_tree_add_item(primary_header_tree, hf_ccsds_length, tvb, offset, 2, ENC_BIG_ENDIAN);
if (ccsds_length > reported_length) {
expert_add_info(pinfo, item, &ei_ccsds_length_error);
}
offset += 2;
proto_item_set_end(primary_header, tvb, offset);
/* build the ccsds secondary header tree */
if ( first_word & HDR_SECHDR )
{
secondary_header_tree = proto_tree_add_subtree(ccsds_tree, tvb, offset, CCSDS_SECONDARY_HEADER_LENGTH,
ett_ccsds_secondary_header, &secondary_header, "Secondary CCSDS Header");
/* command ccsds secondary header flags */
coarse_time = tvb_get_ntohl(tvb, offset);
proto_tree_add_item(secondary_header_tree, hf_ccsds_coarse_time, tvb, offset, 4, ENC_BIG_ENDIAN);
offset += 4;
fine_time = tvb_get_guint8(tvb, offset);
proto_tree_add_item(secondary_header_tree, hf_ccsds_fine_time, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
time_string = embedded_time_to_string ( coarse_time, fine_time );
proto_tree_add_string(secondary_header_tree, hf_ccsds_embedded_time, tvb, offset-5, 5, time_string);
proto_tree_add_item(secondary_header_tree, hf_ccsds_timeid, tvb, offset, 1, ENC_BIG_ENDIAN);
checkword_item = proto_tree_add_item(secondary_header_tree, hf_ccsds_checkword_flag, tvb, offset, 1, ENC_BIG_ENDIAN);
/* Global Preference: how to handle checkword flag */
switch (global_dissect_checkword) {
case 0:
/* force checkword presence flag to be false */
checkword_flag = 0;
break;
case 1:
/* force checkword presence flag to be true */
checkword_flag = 1;
break;
default:
/* use value of checkword presence flag from header */
checkword_flag = (tvb_get_guint8(tvb, offset)&0x20) >> 5;
break;
}
/* payload specific ccsds secondary header flags */
if ( first_word & HDR_TYPE )
{
proto_tree_add_item(secondary_header_tree, hf_ccsds_zoe, tvb, offset, 1, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_packet_type_unused, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
proto_tree_add_item(secondary_header_tree, hf_ccsds_vid, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(secondary_header_tree, hf_ccsds_dcc, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
}
/* core specific ccsds secondary header flags */
else
{
/* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare1, tvb, offset, 1, ENC_BIG_ENDIAN); */
proto_tree_add_item(secondary_header_tree, hf_ccsds_packet_type, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
/* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare2, tvb, offset, 2, ENC_BIG_ENDIAN); */
proto_tree_add_item(secondary_header_tree, hf_ccsds_element_id, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_cmd_data_packet, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_format_version_id, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item(secondary_header_tree, hf_ccsds_extended_format_id, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
/* proto_tree_add_item(secondary_header_tree, hf_ccsds_spare3, tvb, offset, 1, ENC_BIG_ENDIAN); */
++offset;
proto_tree_add_item(secondary_header_tree, hf_ccsds_frame_id, tvb, offset, 1, ENC_BIG_ENDIAN);
++offset;
}
/* finish the ccsds secondary header */
proto_item_set_end(secondary_header, tvb, offset);
}