osmith
/
wireshark
forked from osmocom/wireshark
1
0
Fork 0
Code Pull Requests Releases Wiki Activity

Couchbase: Simplify PDU length detection 

1. The fixed size of a Couchbase header is 24 bytes (not 12)
2. The "overflow detection" won't work as the test would wrap.
   In addition to that the (current) version of the server will
   drop a connection if it encounters a frame bigger than 30MB
   and the biggest "legal" packets are currently less than 21MB.
This commit is contained in:
Trond Norbye 2022-02-24 13:32:28 +01:00
parent 33f5b9e145
commit f5277d0186
1 changed files with 20 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
epan/dissectors/packet-couchbase.c
View File

@ -1067,24 +1067,6 @@ static guint32 get_body_length(tvbuff_t *tvb) {
return tvb_get_ntohl(tvb, 8);
}
static guint
get_couchbase_pdu_len(packet_info *pinfo _U_, tvbuff_t *tvb,
int offset, void *data _U_)
{
guint32 bodylen;
/* Get the length of the memcache body */
bodylen = tvb_get_ntohl(tvb, offset + 8);
/* That length doesn't include the header; add that in */
if ((bodylen + COUCHBASE_HEADER_LEN) > G_MAXUINT32) {
return G_MAXUINT32;
} else {
return bodylen + COUCHBASE_HEADER_LEN;
}
}
/* Returns true if the specified opcode's response value is JSON. */
static gboolean
has_json_value(gboolean is_request, guint8 opcode)
@ -3136,18 +3118,28 @@ dissect_couchbase(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* dat
return tvb_reported_length(tvb);
}
/* Dissect tcp packets based on the type of protocol (text/binary) */
static guint
get_couchbase_pdu_length(packet_info *pinfo _U_, tvbuff_t *tvb, int offset,
void *data _U_) {
// See https://github.com/couchbase/kv_engine/blob/master/docs/BinaryProtocol.md#packet-structure
// for a description of each packet.
// The "length" field is located at offset 8 within the frame and does
// not include the fixed header.
return tvb_get_ntohl(tvb, offset + 8) + COUCHBASE_HEADER_LEN;
}
/* Dissect the couchbase packet */
static int
dissect_couchbase_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data)
{
guint8 magic = get_magic(tvb);
if (try_val_to_str(magic, magic_vals) == NULL) {
dissect_couchbase_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
void *data) {
if (try_val_to_str(tvb_get_guint8(tvb, 0), magic_vals) == NULL) {
// Magic isn't one of the know magics used by the Couchbase dissector
return 0;
}
tcp_dissect_pdus(tvb, pinfo, tree, couchbase_desegment_body, 12,
get_couchbase_pdu_len, dissect_couchbase, data);
tcp_dissect_pdus(tvb, pinfo, tree, couchbase_desegment_body,
COUCHBASE_HEADER_LEN,
get_couchbase_pdu_length, dissect_couchbase, data);
return tvb_captured_length(tvb);
}
@ -3394,11 +3386,11 @@ proto_register_couchbase(void)
/* Register our configuration options */
couchbase_module = prefs_register_protocol(proto_couchbase, &proto_reg_handoff_couchbase);
couchbase_handle = register_dissector("couchbase", dissect_couchbase_tcp, proto_couchbase);
couchbase_handle = register_dissector("couchbase", dissect_couchbase_pdu, proto_couchbase);
prefs_register_bool_preference(couchbase_module, "desegment_pdus",
"Reassemble PDUs spanning multiple TCP segments",
"Whether the memcache dissector should reassemble PDUs"
"Whether the Couchbase dissector should reassemble PDUs"
" spanning multiple TCP segments."
" To use this option, you must also enable \"Allow subdissectors"
" to reassemble TCP streams\" in the TCP protocol settings.",
@ -3408,8 +3400,6 @@ proto_register_couchbase(void)
"The port used for communicating with the data service via SSL/TLS",
10, &couchbase_ssl_port_pref);
prefs_register_obsolete_preference(couchbase_module, "ssl_port");
}
/* Register the tcp couchbase dissector. */