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Use a dissector table instead of strcmp

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... to map vpp node names to dissector handles.

Wireshark has an easy-to-use string to dissector function handle
hashing scheme, so use it. Thanks to Guy Harris for writing up the
incantation.

Change-Id: I6c1eb609332b0afe87154ba447a98f783e13ca68
Signed-off-by: Dave Barach <dave@barachs.net>
This commit is contained in:
Dave Barach
2018-11-24 18:29:26 -05:00
committed by Damjan Marion
parent ce55bcde5d
commit c2b4dc5981
1 changed files with 50 additions and 29 deletions
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79
extras/wireshark/packet-vpp.c
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@ -88,20 +88,39 @@ static dissector_handle_t vpp_dissector_handle;
static dissector_handle_t vpp_opaque_dissector_handle;
static dissector_handle_t vpp_trace_dissector_handle;
static dissector_handle_t eth_dissector_handle;
static dissector_handle_t ip4_dissector_handle;
static dissector_handle_t ip6_dissector_handle;
static dissector_handle_t udp_dissector_handle;
static dissector_table_t vpp_subdissector_table;
#define foreach_node_to_dissector_handle \
_("ip6-lookup", "ipv6", ip6_dissector_handle) \
_("ip4-input-no-checksum", "ip", ip4_dissector_handle) \
_("ip4-lookup", "ip", ip4_dissector_handle) \
_("ip4-local", "ip", ip4_dissector_handle) \
_("ip4-udp-lookup", "ip", udp_dissector_handle) \
_("ip4-icmp-error", "ip", ip4_dissector_handle) \
_("ip4-glean", "ip", ip4_dissector_handle) \
_("ethernet-input", "eth_maybefcs", eth_dissector_handle)
/* List of next dissector names that we know about */
#define foreach_next_dissector \
_(eth_maybefcs) \
_(ip) \
_(ipv6) \
_(udp)
#define _(a) static dissector_handle_t a##_dissector_handle;
foreach_next_dissector;
#undef _
/*
* node-name, next dissector name pairs
*
* Unfortunately, -Werror=c++-compat causes
* the node names "ipX-not-enabled" to throw a shoe if
* not explicitly quoted. Never mind that the first macro
* arg is [only] used as a string (#xxx).
*/
#define foreach_node_to_dissector_pair \
_("ip6-lookup", ipv6) \
_("ip4-input", ip) \
_("ip4-not-enabled", ip) \
_("ip4-input-no-checksum", ip) \
_("ip4-lookup", ip) \
_("ip4-local", ip) \
_("ip4-udp-lookup", udp) \
_("ip4-icmp-error", ip) \
_("ip4-glean", ip) \
_("ethernet-input", eth_maybefcs)
static void
add_multi_line_string_to_tree(proto_tree *tree, tvbuff_t *tvb, gint start,
@ -610,7 +629,7 @@ dissect_vpp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
guint8 name_length;
guint8 *name;
guint16 trace_length;
int i, found;
int i;
static const int *buffer_flags[] = {
&hf_vpp_buffer_flag_non_default_freelist,
&hf_vpp_buffer_flag_traced,
@ -730,19 +749,15 @@ dissect_vpp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
eth_tvb = tvb_new_subset_remaining (tvb, offset);
found = 0;
#define _(a,b,c) \
{ \
if (!strcmp (name, a)) { \
call_dissector (c, eth_tvb, pinfo, tree); \
found = 1; \
} \
}
foreach_node_to_dissector_handle;
#undef _
if (found == 0)
call_dissector (eth_dissector_handle, eth_tvb, pinfo, tree);
/*
* Delegate the rest of the packet dissection to the per-node
* next dissector in the foreach_node_to_dissector_pair list
*
* Failing that, pretend its an ethernet packet
*/
if (!dissector_try_string (vpp_subdissector_table, name, eth_tvb,
pinfo, tree, NULL))
call_dissector (eth_maybefcs_dissector_handle, eth_tvb, pinfo, tree);
g_free (name);
return tvb_captured_length(tvb);
@ -958,8 +973,14 @@ proto_register_vpp(void)
proto_register_subtree_array (ett_trace, array_length(ett_trace));
register_dissector("vppTrace", dissect_vpp_trace, proto_vpp_trace);
#define _(a,b,c) c = find_dissector(b);
foreach_node_to_dissector_handle;
vpp_subdissector_table = register_dissector_table
("vpp", "VPP per-node next dissector table", proto_vpp,
FT_STRING, BASE_NONE);
#define _(n,d) \
d##_dissector_handle = find_dissector(#d); \
dissector_add_string ("vpp", n, d##_dissector_handle);
foreach_node_to_dissector_pair;
#undef _
}