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Add proper "Decode As" mechanism for FLIP payload instead of (many) preferences. 

Other cleanup with FLIP dissector while in the neighborhood.

Change-Id: I0ecdea447979b0ba508a8bb84bd67e4eb4b32a70
Reviewed-on: https://code.wireshark.org/review/7896
Reviewed-by: Michael Mann <mmann78@netscape.net>
This commit is contained in:
Michael Mann 2015-04-02 19:33:39 -04:00
parent cec99abac9
commit 3ab3158700
3 changed files with 74 additions and 358 deletions
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429
epan/dissectors/packet-flip.c
View File

@ -47,6 +47,7 @@
#include <epan/packet.h>
#include <epan/etypes.h>
#include <epan/decode_as.h>
#include <epan/in_cksum.h>
#include <epan/prefs.h>
@ -78,66 +79,29 @@ static int hf_flip_chksum_chksum = -1;
#define FLIP_CHKSUM_HDR_LEN (4)
#define FLIP_EXTENSION_HDR_MIN_LEN (4)
#if 0
static const value_string flip_short_header_names[]={
{ FLIP_BASIC, "BASIC" },
{ FLIP_CHKSUM, "CHKSUM"},
{ 0, NULL}
};
static const value_string flip_long_header_names[] = {
{ FLIP_BASIC, "Basic"},
{ FLIP_CHKSUM, "Checksum"},
{ 0, NULL }
};
#endif
static const value_string flip_boolean[] = {
{0, "No"},
{1, "Yes"},
{0, NULL}
};
static const value_string flip_etype[] = {
{ FLIP_CHKSUM, "Checksum" },
{ 0, NULL }
};
#define FLIP_PAYLOAD_DECODING_MODE_NONE (0)
#define FLIP_PAYLOAD_DECODING_MODE_HEURISTIC (1)
#define FLIP_PAYLOAD_DECODING_MODE_FORCED (2)
static dissector_table_t subdissector_table;
static const enum_val_t flip_payload_decoding_modes[] = {
{"none", "no decoding", FLIP_PAYLOAD_DECODING_MODE_NONE},
{"heuristic", "heuristic", FLIP_PAYLOAD_DECODING_MODE_HEURISTIC},
{"forced", "forced", FLIP_PAYLOAD_DECODING_MODE_FORCED},
{NULL, NULL, 0}
};
static gint global_flip_payload_decoding_mode =
FLIP_PAYLOAD_DECODING_MODE_HEURISTIC;
static gboolean is_heur_enabled_rtp = TRUE;
static gboolean is_heur_enabled_rtcp = TRUE;
static const char *global_forced_protocol = "data";
static gboolean is_forced_handle_ok = FALSE;
static dissector_handle_t data_handle = NULL;
static gint ett_flip = -1;
static gint ett_flip_basic = -1;
static gint ett_flip_chksum = -1;
static gint ett_flip_payload = -1;
static dissector_handle_t rtp_handle;
static dissector_handle_t rtcp_handle;
static dissector_handle_t data_handle;
static dissector_handle_t forced_handle;
static void flip_prompt(packet_info *pinfo _U_, gchar* result)
{
g_snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Decode FLIP payload protocol as");
}
/* Forward declaration. */
static gboolean
is_payload_rtp(tvbuff_t *tvb);
static gboolean
is_payload_rtcp(tvbuff_t *tvb);
static gpointer flip_value(packet_info *pinfo _U_)
{
return 0;
}
/* Dissect the checksum extension header. */
static int
@ -150,7 +114,6 @@ dissect_flip_chksum_hdr(tvbuff_t *tvb,
proto_tree *chksum_hdr_tree;
guint32 dw;
guint8 chksum_hdr_etype;
guint8 chksum_hdr_spare;
guint8 chksum_hdr_ext;
guint16 chksum_hdr_chksum;
@ -164,7 +127,6 @@ dissect_flip_chksum_hdr(tvbuff_t *tvb,
dw = tvb_get_ntohl(tvb, offset);
chksum_hdr_etype = (guint8) ((dw & 0xFF000000) >> 24);
chksum_hdr_spare = (guint8) ((dw & 0x00FE0000) >> 17);
chksum_hdr_ext = (guint8) ((dw & 0x00010000) >> 16);
chksum_hdr_chksum = (guint16) (dw & 0x0000FFFF);
@ -187,17 +149,11 @@ dissect_flip_chksum_hdr(tvbuff_t *tvb,
flip_etype,
"Unknown"));
/* SPARE: 7 bits */
proto_tree_add_uint_format_value(chksum_hdr_tree, hf_flip_chksum_spare,
tvb, offset + 1, 1, dw,
"%d (0x%02x)",
chksum_hdr_spare, chksum_hdr_spare);
proto_tree_add_item(chksum_hdr_tree, hf_flip_chksum_spare, tvb, offset, 4, ENC_BIG_ENDIAN);
/* EXT HDR: 1 bit */
proto_tree_add_uint_format_value(chksum_hdr_tree, hf_flip_chksum_e,
tvb, offset + 1, 1, dw,
"%s", val_to_str_const(chksum_hdr_ext,
flip_boolean,
"Unknown"));
proto_tree_add_item(chksum_hdr_tree, hf_flip_chksum_e,
tvb, offset, 4, ENC_BIG_ENDIAN);
/* CHKSUM: 16 bits. */
proto_tree_add_uint_format_value(
chksum_hdr_tree,
@ -226,151 +182,32 @@ dissect_flip_chksum_hdr(tvbuff_t *tvb,
} /* dissect_flip_chksum_hdr() */
/* Detection logic grabbed from packet-rtp.c and modified. */
#define RTP_VERSION(octet) ((octet) >> 6)
#define RTP_MARKER(octet) ((octet) & 0x80)
#define RTP_PAYLOAD_TYPE(octet) ((octet) & 0x7F)
#define RTP_V2_HEADER_MIN_LEN 12
static gboolean
is_payload_rtp(tvbuff_t *tvb)
{
guint8 octet1, octet2;
unsigned int version;
unsigned int payload_type;
unsigned int offset;
gint len_remaining;
offset = 0;
len_remaining = tvb_length_remaining(tvb, offset);
if (len_remaining < RTP_V2_HEADER_MIN_LEN) {
return FALSE;
}
octet1 = tvb_get_guint8(tvb, offset);
version = RTP_VERSION(octet1);
/* Accept only version 2. */
if (version != 2) {
return FALSE;
}
octet2 = tvb_get_guint8(tvb, offset + 1);
payload_type = RTP_PAYLOAD_TYPE(octet2);
if ((payload_type <= PT_H263)
||
((payload_type >= PT_UNDF_96) && (payload_type <= PT_UNDF_127))) {
/* OK */
;
}
else {
return FALSE;
}
return TRUE;
} /* is_payload_rtp() */
/* Detection logic grabbed from packet-rtcp.c and modified. */
#define RTCP_SR 200
#define RTCP_RR 201
#define RTCP_BYE 203
#define RTCP_APP 204
#define RTCP_V2_HEADER_MIN_LEN 4
static gboolean
is_payload_rtcp(tvbuff_t *tvb)
{
unsigned int first_byte;
unsigned int packet_type;
unsigned int offset;
gint len_remaining;
offset = 0;
len_remaining = tvb_length_remaining(tvb, offset);
if (len_remaining < RTCP_V2_HEADER_MIN_LEN) {
return FALSE;
}
/* Look at first byte */
first_byte = tvb_get_guint8(tvb, offset);
/* Are version bits set to 2? */
if (((first_byte & 0xC0) >> 6) != 2) {
return FALSE;
}
/* Look at packet type */
packet_type = tvb_get_guint8(tvb, offset + 1);
/* First packet within compound packet is supposed to be a sender
or receiver report.
- allow BYE because this happens anyway
- allow APP because TBCP ("PoC1") packets aren't compound... */
if (!((packet_type == RTCP_SR) || (packet_type == RTCP_RR) ||
(packet_type == RTCP_BYE) || (packet_type == RTCP_APP))) {
return FALSE;
}
/* Overall length must be a multiple of 4 bytes */
if (tvb_reported_length(tvb) % 4) {
return FALSE;
}
return TRUE;
} /* is_payload_rtcp() */
/* Protocol dissection */
static int
dissect_flip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
proto_item *ti;
proto_tree *flip_tree;
proto_tree *basic_hdr_tree;
proto_item *ti = NULL;
proto_tree *flip_tree = NULL;
proto_tree *basic_hdr_tree = NULL;
tvbuff_t *flip_tvb;
guint32 dw1;
guint32 dw2;
/* Basic header fields. */
guint8 basic_hdr_ext;
guint8 basic_hdr_reserved;
guint32 basic_hdr_flow_id;
guint16 basic_hdr_seqnum;
guint16 basic_hdr_len;
gboolean ext_hdr;
gboolean ext_hdr = FALSE;
gint bytes_dissected;
gint bytes_dissected = 0;
gint payload_len;
gint frame_len;
gint flip_len;
gint offset;
gint offset = 0;
/* Error handling for basic header. */
gboolean is_faulty_frame;
ti = NULL;
flip_tree = NULL;
basic_hdr_tree = NULL;
flip_tvb = NULL;
ext_hdr = FALSE;
bytes_dissected = 0;
offset = 0;
is_faulty_frame = FALSE;
gboolean is_faulty_frame = FALSE;
/* Show this protocol as FLIP. */
col_set_str(pinfo->cinfo, COL_PROTOCOL, "FLIP");
@ -385,10 +222,9 @@ dissect_flip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_
*/
/* Check that there's enough data at least for the basic header. */
frame_len = tvb_length(tvb);
frame_len = tvb_captured_length(tvb);
if (frame_len < FLIP_BASIC_HDR_LEN) {
/* Not enough. This must be a malformed packet. */
goto DISSECT_FLIP_EXIT;
return 0;
}
bytes_dissected += FLIP_BASIC_HDR_LEN;
@ -396,13 +232,11 @@ dissect_flip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_
/* Process the first 32 bits of the basic header. */
dw1 = tvb_get_ntohl(tvb, offset + 0);
basic_hdr_ext = ((dw1 & 0x80000000) >> 31);
basic_hdr_reserved = ((dw1 & 0x70000000) >> 24);
basic_hdr_flow_id = (dw1 & 0x0FFFFFFF);
/* Process the second 32 bits of the basic header. */
dw2 = tvb_get_ntohl(tvb, offset + 4);
basic_hdr_seqnum = (guint16) ((dw2 & 0xFFFF0000) >> 16);
basic_hdr_len = (guint16) (dw2 & 0x0000FFFF);
basic_hdr_len = (guint16) (tvb_get_ntohl(tvb, offset + 4) & 0x0000FFFF);
/* Does the basic header indicate that an extension is next? */
if (basic_hdr_ext == 1) {
@ -427,47 +261,29 @@ dissect_flip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_
/* We are asked for details. */
if (tree) {
if (PTREE_DATA(tree)->visible) {
ti = proto_tree_add_protocol_format(
ti = proto_tree_add_protocol_format(
tree, proto_flip, flip_tvb, 0, flip_len,
"NSN FLIP, FlowID %s",
val_to_str(basic_hdr_flow_id, NULL, "0x%08x"));
}
else {
ti = proto_tree_add_item(tree, proto_flip, flip_tvb, 0,
flip_len, ENC_NA);
}
flip_tree = proto_item_add_subtree(ti, ett_flip);
/* basic header */
basic_hdr_tree = proto_tree_add_subtree(flip_tree, flip_tvb, 0, 8, ett_flip_basic, NULL, "Basic Header");
basic_hdr_tree = proto_tree_add_subtree(flip_tree, flip_tvb, offset, 8, ett_flip_basic, NULL, "Basic Header");
/* Extension header follows? 1 bit. */
proto_tree_add_uint_format_value(basic_hdr_tree,
hf_flip_basic_e,
flip_tvb, offset + 0, 1, dw1,
"%s", val_to_str_const(basic_hdr_ext,
flip_boolean,
"Unknown"));
proto_tree_add_item(basic_hdr_tree, hf_flip_basic_e, flip_tvb, offset, 4, ENC_BIG_ENDIAN);
/* Reserved: 3 bits. */
proto_tree_add_uint_format_value(basic_hdr_tree,
hf_flip_basic_reserved,
flip_tvb, offset + 0, 1, dw1,
"%d", basic_hdr_reserved);
proto_tree_add_item(basic_hdr_tree, hf_flip_basic_reserved, flip_tvb, offset, 4, ENC_BIG_ENDIAN);
/* Flow ID: 28 bits. */
proto_tree_add_item(basic_hdr_tree, hf_flip_basic_flowid,
flip_tvb, offset + 0, 4, ENC_BIG_ENDIAN);
proto_tree_add_item(basic_hdr_tree, hf_flip_basic_flowid, flip_tvb, offset, 4, ENC_BIG_ENDIAN);
/* Sequence number: 16 bits. */
proto_tree_add_uint_format_value(basic_hdr_tree, hf_flip_basic_seqnum,
flip_tvb, offset + 4, 2, dw2,
"%d (0x%04x)",
basic_hdr_seqnum, basic_hdr_seqnum);
proto_tree_add_item(basic_hdr_tree, hf_flip_basic_seqnum, flip_tvb, offset + 4, 2, ENC_BIG_ENDIAN);
/* Packet length: 16 bits. */
proto_tree_add_uint_format_value(basic_hdr_tree, hf_flip_basic_len,
flip_tvb, offset + 6, 2, dw2,
"%d (0x%04x)",
basic_hdr_len, basic_hdr_len);
proto_tree_add_item(basic_hdr_tree, hf_flip_basic_len, flip_tvb, offset + 6, 2, ENC_BIG_ENDIAN);
}
offset += FLIP_BASIC_HDR_LEN;
@ -492,8 +308,7 @@ dissect_flip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_
/*
* Now we know that the basic header is sensible.
*/
payload_len = basic_hdr_len;
payload_len -= FLIP_BASIC_HDR_LEN;
payload_len = basic_hdr_len - FLIP_BASIC_HDR_LEN;
/*
* Dissect extension headers (if any).
@ -557,76 +372,17 @@ dissect_flip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_
*/
if (payload_len > 0) {
dissector_handle_t handle;
tvbuff_t *payload_tvb;
gint data_len;
gboolean has_user_messed_up;
has_user_messed_up = FALSE;
payload_tvb = tvb_new_subset_length(flip_tvb, offset, payload_len);
payload_tvb = tvb_new_subset_length(flip_tvb, offset,
payload_len);
/*
* 1) no decoding -> data
* 2) heuristic decoding
* 3) forced decoding
*/
switch (global_flip_payload_decoding_mode) {
case FLIP_PAYLOAD_DECODING_MODE_NONE:
/* Dissect as data. */
handle = data_handle;
break;
case FLIP_PAYLOAD_DECODING_MODE_HEURISTIC:
if ((is_heur_enabled_rtp == TRUE)
&&
(is_payload_rtp(payload_tvb) == TRUE)) {
/* Dissect as RTP. */
handle = rtp_handle;
}
else if ((is_heur_enabled_rtcp == TRUE)
&&
(is_payload_rtcp(payload_tvb))) {
/* Dissect as RTCP. */
handle = rtcp_handle;
}
else {
/* Dissect as data. */
handle = data_handle;
}
break;
case FLIP_PAYLOAD_DECODING_MODE_FORCED:
if (is_forced_handle_ok == TRUE) {
handle = forced_handle;
}
else {
/* Use data as backup. */
handle = data_handle;
/* Tell the user he messed up. */
has_user_messed_up = TRUE;
}
break;
default:
/* Fault in dissector's internal logic. */
DISSECTOR_ASSERT(0);
break;
}
/*
* If tree is NULL, we still cannot quit, we must give
* the RTP/RTCP/data dissectors a chance to fill in
* the protocol column.
*/
data_len = call_dissector(handle, payload_tvb, pinfo, tree);
if (has_user_messed_up == TRUE) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"Invalid user dissector \"%s\"",
global_forced_protocol);
/* Functionality for choosing subdissector is controlled through Decode As as FLIP doesn't
have a unique identifier to determine subdissector */
data_len = dissector_try_uint(subdissector_table, 0, payload_tvb, pinfo, tree);
if (data_len <= 0)
{
data_len = call_dissector(data_handle, payload_tvb, pinfo, tree);
}
bytes_dissected += data_len;
@ -648,8 +404,8 @@ proto_register_flip(void)
* Basic header.
*/
{&hf_flip_basic_e,
{"Extension Header Follows", "flip.basic.e", FT_UINT32, BASE_DEC,
VALS(flip_boolean), 0x80000000, NULL, HFILL}
{"Extension Header Follows", "flip.basic.e", FT_BOOLEAN, 32,
TFS(&tfs_yes_no), 0x80000000, NULL, HFILL}
},
{&hf_flip_basic_reserved,
{"Reserved", "flip.basic.reserved", FT_UINT32, BASE_DEC,
@ -660,12 +416,12 @@ proto_register_flip(void)
NULL, 0x0FFFFFFF, "Basic Header Flow ID", HFILL}
},
{&hf_flip_basic_seqnum,
{"Seqnum", "flip.basic.seqnum", FT_UINT32, BASE_DEC,
NULL, 0xFFFF0000, "Basic Header Sequence Number", HFILL}
{"Seqnum", "flip.basic.seqnum", FT_UINT16, BASE_DEC_HEX,
NULL, 0x0, "Basic Header Sequence Number", HFILL}
},
{&hf_flip_basic_len,
{"Len", "flip.basic.len", FT_UINT32, BASE_DEC,
NULL, 0x0000FFFF, "Basic Header Packet Length", HFILL}
{"Len", "flip.basic.len", FT_UINT16, BASE_DEC_HEX,
NULL, 0x0, "Basic Header Packet Length", HFILL}
},
/*
* Checksum header.
@ -675,12 +431,12 @@ proto_register_flip(void)
VALS(flip_etype), 0xFF000000, "Checksum Header Extension Type", HFILL}
},
{&hf_flip_chksum_spare,
{"Spare", "flip.chksum.spare", FT_UINT32, BASE_DEC,
{"Spare", "flip.chksum.spare", FT_UINT32, BASE_DEC_HEX,
NULL, 0x00FE0000, "Checksum Header Spare", HFILL}
},
{&hf_flip_chksum_e,
{"Extension Header Follows", "flip.chksum.e", FT_UINT32, BASE_DEC,
VALS(flip_boolean), 0x00010000, NULL, HFILL}
{"Extension Header Follows", "flip.chksum.e", FT_BOOLEAN, 32,
TFS(&tfs_yes_no), 0x00010000, NULL, HFILL}
},
{&hf_flip_chksum_chksum,
{"Checksum", "flip.chksum.chksum", FT_UINT32, BASE_HEX,
@ -697,6 +453,12 @@ proto_register_flip(void)
module_t *flip_module;
/* Decode As handling */
static build_valid_func flip_da_build_value[1] = {flip_value};
static decode_as_value_t flip_da_values = {flip_prompt, 1, flip_da_build_value};
static decode_as_t flip_da = {"flip", "FLIP Payload", "flip.payload", 1, 0, &flip_da_values, NULL, NULL,
decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};
proto_flip = proto_register_protocol(
"NSN FLIP", /* name */
"FLIP", /* short name */
@ -706,52 +468,19 @@ proto_register_flip(void)
proto_register_field_array(proto_flip, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
subdissector_table = register_dissector_table("flip.payload", "FLIP subdissector", FT_UINT32, BASE_HEX);
flip_module = prefs_register_protocol(proto_flip,
proto_reg_handoff_flip);
flip_module = prefs_register_protocol(proto_flip, NULL);
/* Register preferences */
prefs_register_enum_preference(
flip_module,
"decoding_mode",
"FLIP payload decoding mode",
"Decode FLIP payload according to mode",
&global_flip_payload_decoding_mode,
flip_payload_decoding_modes,
TRUE);
/* Register preferences - now obsolete because of Decode As*/
prefs_register_obsolete_preference(flip_module, "decoding_mode");
prefs_register_obsolete_preference(flip_module, "heur_enabled_protocols");
prefs_register_obsolete_preference(flip_module, "heur_decode_rtp");
prefs_register_obsolete_preference(flip_module, "heur_decode_rtcp");
prefs_register_obsolete_preference(flip_module, "forced_protocol");
prefs_register_obsolete_preference(flip_module, "forced_decode");
prefs_register_static_text_preference(
flip_module,
"heur_enabled_protocols",
"Heuristic mode: enabled protocols",
"Enabled protocols for heuristic mode");
prefs_register_bool_preference(
flip_module,
"heur_decode_rtp",
"RTP",
"Decode payload as RTP if detected",
&is_heur_enabled_rtp);
prefs_register_bool_preference(
flip_module,
"heur_decode_rtcp",
"RTCP",
"Decode payload as RTCP if detected",
&is_heur_enabled_rtcp);
prefs_register_static_text_preference(
flip_module,
"forced_protocol",
"Forced mode: decode to user-specified protocol",
"Mapping of flow IDs to their decodings");
prefs_register_string_preference(
flip_module,
"forced_decode",
"Protocol name",
"Decoding to user-defined protocol",
&global_forced_protocol);
register_decode_as(&flip_da);
} /* proto_register_flip() */
@ -761,26 +490,10 @@ proto_reg_handoff_flip(void)
{
dissector_handle_t flip_handle;
static gboolean flip_prefs_initialized = FALSE;
if (flip_prefs_initialized == FALSE) {
flip_handle = new_create_dissector_handle(dissect_flip, proto_flip);
dissector_add_uint("ethertype", ETHERTYPE_FLIP, flip_handle);
rtp_handle = find_dissector("rtp");
rtcp_handle = find_dissector("rtcp");
data_handle = find_dissector("data");
flip_prefs_initialized = TRUE;
}
/* Preferences update: check user-specified dissector. */
is_forced_handle_ok = FALSE;
forced_handle = find_dissector(global_forced_protocol);
if (forced_handle != NULL) {
is_forced_handle_ok = TRUE;
}
flip_handle = new_create_dissector_handle(dissect_flip, proto_flip);
dissector_add_uint("ethertype", ETHERTYPE_FLIP, flip_handle);
data_handle = find_dissector("data");
} /* proto_reg_handoff_flip() */
/*

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

@ -6516,6 +6516,7 @@ proto_reg_handoff_rtcp(void)
*/
rtcp_handle = find_dissector("rtcp");
dissector_add_for_decode_as("udp.port", rtcp_handle);
dissector_add_for_decode_as("flip.payload", rtcp_handle );
heur_dissector_add( "udp", dissect_rtcp_heur, proto_rtcp);
heur_dissector_add("stun", dissect_rtcp_heur, proto_rtcp);

2
epan/dissectors/packet-rtp.c
View File

@ -3721,6 +3721,8 @@ proto_reg_handoff_rtp(void)
rtp_hdr_ext_ed137a_handle = find_dissector("rtp.ext.ed137a");
dissector_add_uint("rtp.hdr_ext", RTP_ED137_SIG, rtp_hdr_ext_ed137_handle);
dissector_add_uint("rtp.hdr_ext", RTP_ED137A_SIG, rtp_hdr_ext_ed137a_handle);
dissector_add_for_decode_as("flip.payload", rtp_handle );
rtcp_handle = find_dissector("rtcp");
data_handle = find_dissector("data");