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-rw-r--r--epan/dissectors/packet-mpls.c243
1 files changed, 144 insertions, 99 deletions
diff --git a/epan/dissectors/packet-mpls.c b/epan/dissectors/packet-mpls.c
index bd96efd9..54f68130 100644
--- a/epan/dissectors/packet-mpls.c
+++ b/epan/dissectors/packet-mpls.c
@@ -61,15 +61,15 @@
void proto_register_mpls(void);
void proto_reg_handoff_mpls(void);
-static gint proto_mpls = -1;
-static gint proto_pw_ach = -1;
-static gint proto_pw_ach_mcc = -1;
-static gint proto_pw_mcw = -1;
-
-static gint ett_mpls = -1;
-static gint ett_mpls_pw_ach = -1;
-static gint ett_mpls_pw_ach_mcc = -1;
-static gint ett_mpls_pw_mcw = -1;
+static int proto_mpls;
+static int proto_pw_ach;
+static int proto_pw_ach_mcc;
+static int proto_pw_mcw;
+
+static int ett_mpls;
+static int ett_mpls_pw_ach;
+static int ett_mpls_pw_ach_mcc;
+static int ett_mpls_pw_mcw;
static char PW_ACH[50] = "PW Associated Channel Header";
const value_string special_labels[] = {
@@ -94,29 +94,34 @@ static dissector_handle_t mpls_handle;
static dissector_handle_t mpls_pwcw_handle;
static dissector_handle_t mpls_mcc_handle;
+/*
+ * RFC 8469 deprecated Ethernet without CW, so default this to false.
+ * https://datatracker.ietf.org/doc/html/rfc8469
+ */
+static bool mpls_try_heuristic_first;
/* For RFC6391 - Flow aware transport of pseudowire over a mpls PSN*/
-static gboolean mpls_bos_flowlabel = FALSE;
+static bool mpls_bos_flowlabel;
-static int hf_mpls_label = -1;
-static int hf_mpls_label_special = -1;
-static int hf_mpls_exp = -1;
-static int hf_mpls_bos = -1;
-static int hf_mpls_ttl = -1;
+static int hf_mpls_label;
+static int hf_mpls_label_special;
+static int hf_mpls_exp;
+static int hf_mpls_bos;
+static int hf_mpls_ttl;
-static int hf_mpls_pw_ach_ver = -1;
-static int hf_mpls_pw_ach_res = -1;
-static int hf_mpls_pw_ach_channel_type = -1;
+static int hf_mpls_pw_ach_ver;
+static int hf_mpls_pw_ach_res;
+static int hf_mpls_pw_ach_channel_type;
-static int hf_mpls_pw_ach_mcc_proto = -1;
+static int hf_mpls_pw_ach_mcc_proto;
-static int hf_mpls_pw_mcw_flags = -1;
-static int hf_mpls_pw_mcw_length = -1;
-static int hf_mpls_pw_mcw_sequence_number = -1;
+static int hf_mpls_pw_mcw_flags;
+static int hf_mpls_pw_mcw_length;
+static int hf_mpls_pw_mcw_sequence_number;
-static expert_field ei_mpls_pw_ach_error_processing_message = EI_INIT;
-static expert_field ei_mpls_pw_ach_res = EI_INIT;
-static expert_field ei_mpls_pw_mcw_error_processing_message = EI_INIT;
-static expert_field ei_mpls_invalid_label = EI_INIT;
+static expert_field ei_mpls_pw_ach_error_processing_message;
+static expert_field ei_mpls_pw_ach_res;
+static expert_field ei_mpls_pw_mcw_error_processing_message;
+static expert_field ei_mpls_invalid_label;
#if 0 /*not used yet*/
/*
@@ -199,25 +204,42 @@ static const value_string mpls_pwac_types[] = {
static value_string_ext mpls_pwac_types_ext = VALUE_STRING_EXT_INIT(mpls_pwac_types);
static dissector_table_t mpls_subdissector_table;
+/*
+ * Post-stack First Nibble
+ * https://datatracker.ietf.org/doc/html/draft-ietf-mpls-1stnibble-06
+ */
+static dissector_table_t mpls_pfn_subdissector_table;
+static heur_dissector_list_t mpls_heur_subdissector_list;
-static void mpls_prompt(packet_info *pinfo, gchar* result)
+static void mpls_prompt(packet_info *pinfo, char* result)
{
snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Data after label %u as",
GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 0)));
}
-static gpointer mpls_value(packet_info *pinfo)
+static void *mpls_value(packet_info *pinfo)
{
return p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 0);
}
-static void pw_ach_prompt(packet_info *pinfo, gchar* result)
+static void mpls_pfn_prompt(packet_info *pinfo, char* result)
+{
+ snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Data after post-stack first nibble %u as",
+ GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 1)));
+}
+
+static void *mpls_pfn_value(packet_info *pinfo)
+{
+ return p_get_proto_data(pinfo->pool, pinfo, proto_mpls, 1);
+}
+
+static void pw_ach_prompt(packet_info *pinfo, char* result)
{
snprintf(result, MAX_DECODE_AS_PROMPT_LEN, "Channel type 0x%x as",
GPOINTER_TO_UINT(p_get_proto_data(pinfo->pool, pinfo, proto_pw_ach, 0)));
}
-static gpointer pw_ach_value(packet_info *pinfo)
+static void *pw_ach_value(packet_info *pinfo)
{
return p_get_proto_data(pinfo->pool, pinfo, proto_pw_ach, 0);
}
@@ -230,17 +252,17 @@ static gpointer pw_ach_value(packet_info *pinfo)
*/
void
decode_mpls_label(tvbuff_t *tvb, int offset,
- guint32 *label, guint8 *exp,
- guint8 *bos, guint8 *ttl)
+ uint32_t *label, uint8_t *exp,
+ uint8_t *bos, uint8_t *ttl)
{
- guint8 octet0 = tvb_get_guint8(tvb, offset+0);
- guint8 octet1 = tvb_get_guint8(tvb, offset+1);
- guint8 octet2 = tvb_get_guint8(tvb, offset+2);
+ uint8_t octet0 = tvb_get_uint8(tvb, offset+0);
+ uint8_t octet1 = tvb_get_uint8(tvb, offset+1);
+ uint8_t octet2 = tvb_get_uint8(tvb, offset+2);
*label = (octet0 << 12) + (octet1 << 4) + ((octet2 >> 4) & 0xff);
*exp = (octet2 >> 1) & 0x7;
*bos = (octet2 & 0x1);
- *ttl = tvb_get_guint8(tvb, offset+3);
+ *ttl = tvb_get_uint8(tvb, offset+3);
}
/*
@@ -253,7 +275,7 @@ dissect_pw_ach_mcc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* da
tvbuff_t *next_tvb;
proto_tree *mpls_pw_ach_mcc_tree;
proto_item *ti;
- guint32 pid;
+ uint32_t pid;
ti = proto_tree_add_item(tree, proto_pw_ach_mcc, tvb, 0,2, ENC_NA);
mpls_pw_ach_mcc_tree = proto_item_add_subtree(ti, ett_mpls_pw_ach_mcc);
@@ -276,7 +298,7 @@ static int
dissect_pw_ach(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
tvbuff_t *next_tvb;
- guint channel_type;
+ unsigned channel_type;
if (tvb_reported_length_remaining(tvb, 0) < 4) {
proto_tree_add_expert(tree, pinfo, &ei_mpls_pw_ach_error_processing_message, tvb, 0, -1);
@@ -289,7 +311,7 @@ dissect_pw_ach(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _
if (tree) {
proto_tree *mpls_pw_ach_tree;
proto_item *ti;
- guint16 res;
+ uint16_t res;
ti = proto_tree_add_item(tree, proto_pw_ach, tvb, 0, 4, ENC_NA);
mpls_pw_ach_tree = proto_item_add_subtree(ti, ett_mpls_pw_ach);
@@ -297,7 +319,7 @@ dissect_pw_ach(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _
proto_tree_add_item(mpls_pw_ach_tree, hf_mpls_pw_ach_ver,
tvb, 0, 1, ENC_BIG_ENDIAN);
- res = tvb_get_guint8(tvb, 1);
+ res = tvb_get_uint8(tvb, 1);
ti = proto_tree_add_uint(mpls_pw_ach_tree, hf_mpls_pw_ach_res,
tvb, 1, 1, res);
if (res != 0)
@@ -324,12 +346,12 @@ dissect_pw_ach(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _
return tvb_captured_length(tvb);
}
-gboolean
+bool
dissect_try_cw_first_nibble( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
{
- guint8 nibble;
+ uint8_t nibble;
- nibble = (tvb_get_guint8(tvb, 0 ) >> 4) & 0x0F;
+ nibble = (tvb_get_uint8(tvb, 0 ) >> 4) & 0x0F;
switch ( nibble )
{
case 6:
@@ -338,25 +360,25 @@ dissect_try_cw_first_nibble( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree
* word, with the packet's first nibble being 6.
*/
call_dissector(dissector_ipv6, tvb, pinfo, tree);
- return TRUE;
+ return true;
case 4:
/*
* XXX - this could be from an pseudo-wire without a control
* word, with the packet's first nibble being 4.
*/
call_dissector(dissector_ip, tvb, pinfo, tree);
- return TRUE;
+ return true;
case 1:
/*
* XXX - this could be from an pseudo-wire without a control
* word, with the packet's first nibble being 1.
*/
call_dissector(dissector_pw_ach, tvb, pinfo, tree );
- return TRUE;
+ return true;
default:
break;
}
- return FALSE;
+ return false;
}
/*
@@ -399,14 +421,16 @@ static int
dissect_mpls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
int offset = 0;
- guint32 label = MPLS_LABEL_INVALID;
- guint8 exp;
- guint8 bos;
- guint8 ttl;
+ uint32_t label = MPLS_LABEL_INVALID;
+ uint8_t exp;
+ uint8_t bos;
+ uint8_t ttl;
tvbuff_t *next_tvb;
int found;
- guint8 first_nibble;
+ uint8_t first_nibble;
struct mplsinfo mplsinfo;
+ heur_dtbl_entry_t *hdtbl_entry;
+ dissector_handle_t payload_handle;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "MPLS");
col_set_str(pinfo->cinfo, COL_INFO, "MPLS Label Switched Packet");
@@ -483,7 +507,8 @@ dissect_mpls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_
break;
}
- first_nibble = (tvb_get_guint8(tvb, offset) >> 4) & 0x0F;
+ first_nibble = (tvb_get_uint8(tvb, offset) >> 4) & 0x0F;
+ p_add_proto_data(pinfo->pool, pinfo, proto_mpls, 1, GUINT_TO_POINTER(first_nibble));
next_tvb = tvb_new_subset_remaining(tvb, offset);
@@ -492,58 +517,48 @@ dissect_mpls(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_
* If so, use it.
*/
found = dissector_try_uint_new(mpls_subdissector_table, label,
- next_tvb, pinfo, tree, FALSE, &mplsinfo);
+ next_tvb, pinfo, tree, false, &mplsinfo);
if (found) {
/* Yes, there is. */
return tvb_captured_length(tvb);
}
/*
- * No, there isn't, so use the 1st nibble logic (see BCP 4928,
- * RFC 4385 and 5586).
+ * Do we try heuristic dissectors first? This is necessary for, e.g.,
+ * Ethernet without CW where the address begins with a 4 or 6 nibble.
*/
- switch(first_nibble) {
- case 4:
- /*
- * XXX - this could be from an Ethernet pseudo-wire without a
- * control word, with the MAC address's first nibble being 4.
- */
- call_dissector(dissector_ip, next_tvb, pinfo, tree);
- /* IP dissector may reduce the length of the tvb.
- We need to do the same, so that ethernet trailer is detected. */
- set_actual_length(tvb, offset+tvb_reported_length(next_tvb));
- break;
- case 6:
- /*
- * XXX - this could be from an Ethernet pseudo-wire without a
- * control word, with the MAC address's first nibble being 6.
- */
- call_dissector(dissector_ipv6, next_tvb, pinfo, tree);
- /* IPv6 dissector may reduce the length of the tvb.
- We need to do the same, so that ethernet trailer is detected. */
- set_actual_length(tvb, offset+tvb_reported_length(next_tvb));
- break;
- case 1:
- /*
- * XXX - this could be from an Ethernet pseudo-wire without a
- * control word, with the MAC address's first nibble being 1.
- */
- call_dissector(dissector_pw_ach, next_tvb, pinfo, tree);
- break;
- case 0:
- /*
- * If this is an Ethernet pseudo-wire, this could either be
- * Ethernet without a control word and with the first nibble
- * of the destination MAC address being 0 or it could be
- * Ethernet with a control word. Let the "pw_eth_heuristic"
- * dissector try to figure it out.
- */
- call_dissector(dissector_pw_eth_heuristic, next_tvb, pinfo, tree);
- break;
- default:
- call_data_dissector(next_tvb, pinfo, tree);
- break;
+ if (mpls_try_heuristic_first) {
+ if (dissector_try_heuristic(mpls_heur_subdissector_list, next_tvb, pinfo,
+ tree, &hdtbl_entry, NULL)) {
+ return tvb_captured_length(tvb);
+ }
}
+
+ /*
+ * Use the 1st nibble logic (see BCP 128 (RFC 4928), RFC 4385 and 5586).
+ * https://datatracker.ietf.org/doc/html/draft-ietf-mpls-1stnibble-06
+ */
+ if (dissector_try_uint_new(mpls_pfn_subdissector_table, first_nibble,
+ next_tvb, pinfo, tree, false, &mplsinfo)) {
+
+ payload_handle = dissector_get_uint_handle(mpls_pfn_subdissector_table, first_nibble);
+ if (payload_handle == dissector_ip || payload_handle == dissector_ipv6) {
+ /* IPv4 and IPv6 dissectors may reduce the length of the tvb.
+ We need to do the same, so that any Ethernet trailer is detected.
+ */
+ set_actual_length(tvb, offset+tvb_reported_length(next_tvb));
+ }
+ return tvb_captured_length(tvb);
+ }
+
+ if (!mpls_try_heuristic_first) {
+ if (dissector_try_heuristic(mpls_heur_subdissector_list, next_tvb, pinfo,
+ tree, &hdtbl_entry, NULL)) {
+ return tvb_captured_length(tvb);
+ }
+ }
+
+ call_data_dissector(next_tvb, pinfo, tree);
return tvb_captured_length(tvb);
}
@@ -629,7 +644,7 @@ proto_register_mpls(void)
},
};
- static gint *ett[] = {
+ static int *ett[] = {
&ett_mpls,
&ett_mpls_pw_ach,
&ett_mpls_pw_ach_mcc,
@@ -649,6 +664,11 @@ proto_register_mpls(void)
static decode_as_t mpls_da = {"mpls", "mpls.label", 1, 0, &mpls_da_values, NULL, NULL,
decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};
+ static build_valid_func mpls_pfn_da_build_value[1] = {mpls_pfn_value};
+ static decode_as_value_t mpls_pfn_da_values = {mpls_pfn_prompt, 1, mpls_pfn_da_build_value};
+ static decode_as_t mpls_pfn_da = {"mpls", "mpls.pfn", 1, 0, &mpls_pfn_da_values, NULL, NULL,
+ decode_as_default_populate_list, decode_as_default_reset, decode_as_default_change, NULL};
+
static build_valid_func pw_ach_da_build_value[1] = {pw_ach_value};
static decode_as_value_t pw_ach_da_values = {pw_ach_prompt, 1, pw_ach_da_build_value};
static decode_as_t pw_ach_da = {"pwach", "pwach.channel_type", 1, 0, &pw_ach_da_values, NULL, NULL,
@@ -674,9 +694,15 @@ proto_register_mpls(void)
/* FF: mpls subdissector table is indexed by label */
mpls_subdissector_table = register_dissector_table("mpls.label",
- "MPLS protocol",
+ "MPLS label",
proto_mpls, FT_UINT32, BASE_DEC);
+ mpls_pfn_subdissector_table = register_dissector_table("mpls.pfn",
+ "MPLS post-stack first nibble",
+ proto_mpls, FT_UINT8, BASE_HEX);
+
+ mpls_heur_subdissector_list = register_heur_dissector_list_with_description("mpls", "MPLS payload", proto_mpls);
+
pw_ach_subdissector_table = register_dissector_table("pwach.channel_type", "PW Associated Channel Type", proto_pw_ach, FT_UINT16, BASE_HEX);
pw_ach_mcc_subdissector_table = register_dissector_table("mcc.proto", "PW Associated Management Communication Channel Protocol", proto_pw_ach_mcc, FT_UINT16, BASE_HEX);
@@ -685,6 +711,13 @@ proto_register_mpls(void)
prefs_register_obsolete_preference(module_mpls, "mplspref.payload");
+ prefs_register_bool_preference(module_mpls, "try_heuristic_first",
+ "Try heuristic sub-dissectors first",
+ "Try to decode a packet heuristically, e.g. as "
+ "Ethernet without control word, before trying "
+ "sub-dissectors based upon the first nibble.",
+ &mpls_try_heuristic_first);
+
/* RFC6391: Flow aware transport of pseudowire*/
prefs_register_bool_preference(module_mpls,
"flowlabel_in_mpls_header",
@@ -693,6 +726,7 @@ proto_register_mpls(void)
&mpls_bos_flowlabel);
register_decode_as(&mpls_da);
+ register_decode_as(&mpls_pfn_da);
register_decode_as(&pw_ach_da);
}
@@ -726,6 +760,17 @@ proto_reg_handoff_mpls(void)
dissector_ipv6 = find_dissector_add_dependency("ipv6", proto_pw_mcw );
dissector_ip = find_dissector_add_dependency("ip", proto_pw_mcw );
dissector_pw_eth_heuristic = find_dissector_add_dependency("pw_eth_heuristic", proto_pw_mcw);
+
+ /*
+ * Our previous default behavior has been to try the Eth CW heuristic
+ * on first nibble 0. Continue doing that. For other first nibbles
+ * registered to dissectors, "try heuristic first" can be enabled.
+ */
+ dissector_add_for_decode_as("mpls.pfn", mpls_pwcw_handle);
+ dissector_add_uint("mpls.pfn", 0, dissector_pw_eth_heuristic);
+ dissector_add_uint("mpls.pfn", 1, dissector_pw_ach);
+ dissector_add_uint("mpls.pfn", 4, dissector_ip);
+ dissector_add_uint("mpls.pfn", 6, dissector_ipv6);
}
/*
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-27 03:52:10 +0000