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LI5G: Use a dissector table 

Use a dissector table instead of manually managing an array of dissector
handles with a hardcoded size. This also prevents a buffer over-read
from unexpected payload format values (either in a later version of
the protocol or just malformed data.)
This commit is contained in:
John Thacker 2022-02-27 03:28:59 -05:00
parent 257225bf1d
commit 1f88507591
1 changed files with 22 additions and 16 deletions
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38
epan/dissectors/packet-li5g.c
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@ -32,14 +32,13 @@ static int hf_li5g_pld = -1;
#define LI_5G_ATTR_TYPE_MAX 19
/* the min header length */
#define LI_5G_HEADER_LEN_MIN 40
/* 13 payload format */
#define LI_5G_PAYLOAD_FORMAT_MAX 14
static gint ett_li5g = -1;
static gint ett_attrContents[LI_5G_ATTR_TYPE_MAX];
static int hf_li5g_attrContents[LI_5G_ATTR_TYPE_MAX];
static dissector_handle_t li5g_handle;
static dissector_handle_t subProtocol_handle[LI_5G_PAYLOAD_FORMAT_MAX]={NULL};
static dissector_table_t li5g_subdissector_table;
static const value_string pdu_type_vals[] = {
{1, "X2 xIRI"},
@ -104,6 +103,7 @@ dissect_li5g(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_
{
proto_tree *li5g_tree, *attr_tree, *parent=NULL;
proto_item *ti, *attr_ti;
tvbuff_t *payload_tvb;
int offset = LI_5G_HEADER_LEN_MIN, hf_attr = -1;
guint32 headerLen, payloadLen, pduType;
guint16 payloadFormat, attrType, attrLen;
@ -161,8 +161,10 @@ dissect_li5g(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_
li5g_tree->parent=NULL;
}
if (subProtocol_handle[payloadFormat])
call_dissector(subProtocol_handle[payloadFormat], tvb_new_subset_length(tvb, offset, payloadLen), pinfo, li5g_tree);
payload_tvb = tvb_new_subset_length(tvb, offset, payloadLen);
if (!dissector_try_uint(li5g_subdissector_table, payloadFormat, payload_tvb, pinfo, li5g_tree)) {
call_data_dissector(payload_tvb, pinfo, li5g_tree);
}
if (parent)
li5g_tree->parent=parent;
@ -263,6 +265,11 @@ proto_register_li5g(void)
};
proto_li5g = proto_register_protocol("5G Lawful Interception", "5GLI", "5gli");
li5g_handle = register_dissector("li5g", dissect_li5g, proto_li5g);
li5g_subdissector_table = register_dissector_table("li5g.payload", "LI5G Payload Format", proto_li5g, FT_UINT16, BASE_DEC);
proto_register_field_array(proto_li5g, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
}
@ -270,18 +277,17 @@ proto_register_li5g(void)
void
proto_reg_handoff_li5g(void)
{
subProtocol_handle[2]=find_dissector_add_dependency("xiri", proto_li5g);
subProtocol_handle[5]=find_dissector("ip");
subProtocol_handle[6]=find_dissector("ipv6");
subProtocol_handle[7]=find_dissector("eth_maybefcs");
subProtocol_handle[8]=find_dissector("rtp");
subProtocol_handle[9]=find_dissector("sip");
subProtocol_handle[10]=find_dissector("dhcp");
subProtocol_handle[11]=find_dissector("radius");
subProtocol_handle[12]=find_dissector("gtp");
subProtocol_handle[13]=find_dissector("msrp");
dissector_add_uint("li5g.payload", 2, find_dissector_add_dependency("xiri", proto_li5g));
dissector_add_uint("li5g.payload", 5, find_dissector("ip"));
dissector_add_uint("li5g.payload", 6, find_dissector("ipv6"));
dissector_add_uint("li5g.payload", 7, find_dissector("eth_maybefcs"));
dissector_add_uint("li5g.payload", 8, find_dissector("rtp"));
dissector_add_uint("li5g.payload", 9, find_dissector("sip"));
dissector_add_uint("li5g.payload", 10, find_dissector("dhcp"));
dissector_add_uint("li5g.payload", 11, find_dissector("radius"));
dissector_add_uint("li5g.payload", 12, find_dissector("gtp"));
dissector_add_uint("li5g.payload", 13, find_dissector("msrp"));
li5g_handle = register_dissector("li5g", dissect_li5g, proto_li5g);
dissector_add_uint_range_with_preference("tcp.port", "", li5g_handle);
dissector_add_uint_range_with_preference("udp.port", "", li5g_handle);
heur_dissector_add("tls", dissect_li5g_heur, "5G LI over TLS", "li5g_tls", proto_li5g, HEURISTIC_ENABLE);