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Use separate dissectors for LAPD and LAPD-with-Linux-SLL-header. 

That obviates the need to check pinfo->pkt_encap.

Change-Id: I038e065932282ce9d3362fbc9ba6ea653a63f399
Reviewed-on: https://code.wireshark.org/review/25627
Reviewed-by: Guy Harris <guy@alum.mit.edu>
This commit is contained in:
Guy Harris 2018-02-06 00:15:44 -08:00
parent 3ec8338497
commit ea7a5bd02c
1 changed files with 22 additions and 7 deletions
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29
epan/dissectors/packet-lapd.c
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@ -88,6 +88,7 @@ static expert_field ei_lapd_abort = EI_INIT;
static expert_field ei_lapd_checksum_bad = EI_INIT;
static dissector_handle_t lapd_handle;
static dissector_handle_t linux_lapd_handle;
static dissector_handle_t lapd_bitstream_handle;
static dissector_table_t lapd_sapi_dissector_table;
@ -199,7 +200,7 @@ typedef struct lapd_convo_data {
static void
dissect_lapd_full(tvbuff_t*, packet_info*, proto_tree*, gboolean);
dissect_lapd_full(tvbuff_t*, packet_info*, proto_tree*, guint32);
/* got new LAPD frame byte */
static void new_byte(char full_byte, char data[], int *data_len) {
@ -220,6 +221,12 @@ lapd_log_abort(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint offset
expert_add_info_format(pinfo, ti, &ei_lapd_abort, "%s", msg);
}
/*
* Flags to pass to dissect_lapd_full.
*/
#define LAPD_HAS_CRC 0x00000001
#define LAPD_HAS_LINUX_SLL 0x00000002
static int
dissect_lapd_bitstream(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* dissector_data _U_)
{
@ -312,7 +319,7 @@ dissect_lapd_bitstream(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void
lapd_log_abort(tvb, pinfo, tree, offset, "Abort! 6 ones that don't match 0x7e!");
}
dissect_lapd_full(new_tvb, pinfo, tree, TRUE);
dissect_lapd_full(new_tvb, pinfo, tree, LAPD_HAS_CRC);
} else if (ones >= 7) { /* frame reset or 11111111 flag byte */
data_len = 0;
state = OUT_OF_SYNC;
@ -405,15 +412,22 @@ dissect_lapd_bitstream(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void
return tvb_captured_length(tvb);
}
static int
dissect_linux_lapd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
dissect_lapd_full(tvb, pinfo, tree, LAPD_HAS_LINUX_SLL);
return tvb_captured_length(tvb);
}
static int
dissect_lapd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
dissect_lapd_full(tvb, pinfo, tree, FALSE);
dissect_lapd_full(tvb, pinfo, tree, 0);
return tvb_captured_length(tvb);
}
static void
dissect_lapd_full(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean has_crc)
dissect_lapd_full(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, guint32 flags)
{
proto_tree *lapd_tree, *addr_tree;
proto_item *lapd_ti, *addr_ti;
@ -441,7 +455,7 @@ dissect_lapd_full(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean
col_append_fstr(pinfo->cinfo, COL_INFO, "TEI:%02u ", tei);
col_set_fence(pinfo->cinfo, COL_INFO);
if (pinfo->pkt_encap == WTAP_ENCAP_LINUX_LAPD) {
if (flags & LAPD_HAS_LINUX_SLL) {
/* frame is captured via libpcap */
if (pinfo->pseudo_header->lapd.pkttype == 4 /*PACKET_OUTGOING*/) {
if (pinfo->pseudo_header->lapd.we_network) {
@ -537,7 +551,7 @@ dissect_lapd_full(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolean
if (tree)
proto_item_set_len(lapd_ti, lapd_header_len);
if (has_crc) {
if (flags & LAPD_HAS_CRC) {
/* check checksum */
checksum_offset = tvb_reported_length(tvb) - 2;
@ -689,6 +703,7 @@ proto_register_lapd(void)
expert_register_field_array(expert_lapd, ei, array_length(ei));
lapd_handle = register_dissector("lapd", dissect_lapd, proto_lapd);
linux_lapd_handle = register_dissector("linux-lapd", dissect_linux_lapd, proto_lapd);
lapd_bitstream_handle = register_dissector("lapd-bitstream", dissect_lapd_bitstream, proto_lapd);
lapd_sapi_dissector_table = register_dissector_table("lapd.sapi",
@ -723,7 +738,7 @@ proto_reg_handoff_lapd(void)
static guint lapd_sctp_ppi;
if (!init) {
dissector_add_uint("wtap_encap", WTAP_ENCAP_LINUX_LAPD, lapd_handle);
dissector_add_uint("wtap_encap", WTAP_ENCAP_LINUX_LAPD, linux_lapd_handle);
dissector_add_uint("wtap_encap", WTAP_ENCAP_LAPD, lapd_handle);
dissector_add_uint("l2tp.pw_type", L2TPv3_PROTOCOL_LAPD, lapd_handle);