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wireshark/epan/dissectors/packet-epmd.c

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/* packet-epmd.c
* dissector for EPMD (Erlang Port Mapper Daemon) messages;
* this are the messages sent between Erlang nodes and
* the empd process.
* The message formats are derived from the
* lib/kernel/src/erl_epmd.* files as part of the Erlang
* distribution available from http://www.erlang.org/
*
* (c) 2007 Joost Yervante Damad <joost[AT]teluna.org>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald[AT]wireshark.org>
* Copyright 1998 Gerald Combs
*
* Copied from packet-time.c
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "config.h"
#include <epan/packet.h>
#include <epan/conversation.h>
#define PNAME "Erlang Port Mapper Daemon"
#define PSNAME "EPMD"
#define PFNAME "epmd"
void proto_register_epmd(void);
void proto_reg_handoff_epmd(void);
static int proto_epmd = -1;
static int hf_epmd_len = -1;
static int hf_epmd_type = -1;
static int hf_epmd_port_no = -1;
static int hf_epmd_node_type = -1;
static int hf_epmd_protocol = -1;
static int hf_epmd_dist_high = -1;
static int hf_epmd_dist_low = -1;
static int hf_epmd_name_len = -1;
static int hf_epmd_name = -1;
static int hf_epmd_elen = -1;
static int hf_epmd_edata = -1;
static int hf_epmd_names = -1;
static int hf_epmd_result = -1;
static int hf_epmd_creation = -1;
static gint ett_epmd = -1;
static dissector_handle_t epmd_handle = NULL;
/* Other dissectors */
static dissector_handle_t edp_handle = NULL;
#define EPMD_PORT 4369
/* Definitions of message codes */
#define EPMD_ALIVE_REQ 'a'
#define EPMD_ALIVE_OK_RESP 'Y'
#define EPMD_PORT_REQ 'p'
#define EPMD_NAMES_REQ 'n'
#define EPMD_DUMP_REQ 'd'
#define EPMD_KILL_REQ 'k'
#define EPMD_STOP_REQ 's'
/* New epmd messages */
#define EPMD_ALIVE2_REQ 'x' /* 120 */
#define EPMD_PORT2_REQ 'z' /* 122 */
#define EPMD_ALIVE2_RESP 'y' /* 121 */
#define EPMD_PORT2_RESP 'w' /* 119 */
static const value_string message_types[] = {
{ EPMD_ALIVE_REQ , "EPMD_ALIVE_REQ" },
{ EPMD_ALIVE_OK_RESP, "EPMD_ALIVE_OK_RESP" },
{ EPMD_PORT_REQ , "EPMD_PORT_REQ" },
{ EPMD_NAMES_REQ , "EPMD_NAMES_REQ" },
{ EPMD_DUMP_REQ , "EPMD_DUMP_REQ" },
{ EPMD_KILL_REQ , "EPMD_KILL_REQ" },
{ EPMD_STOP_REQ , "EPMD_STOP_REQ" },
{ EPMD_ALIVE2_REQ , "EPMD_ALIVE2_REQ" },
{ EPMD_PORT2_REQ , "EPMD_PORT2_REQ" },
{ EPMD_ALIVE2_RESP , "EPMD_ALIVE2_RESP" },
{ EPMD_PORT2_RESP , "EPMD_PORT2_RESP" },
{ 0, NULL }
};
static const value_string node_type_vals[] = {
{ 72 , "R3 hidden node" },
{ 77 , "R3 erlang node" },
{ 104 , "R4 hidden node" },
{ 109 , "R4 erlang node" },
{ 110 , "R6 nodes" },
{ 0, NULL }
};
static const value_string protocol_vals[] = {
{ 0 , "tcp/ip-v4" },
{ 0, NULL }
};
const value_string epmd_version_vals[] = {
{ 0 , "R3" },
{ 1 , "R4" },
{ 2 , "R5" },
{ 3 , "R5C" },
{ 4 , "R6 dev" },
{ 5 , "R6" },
{ 0, NULL }
};
static void
dissect_epmd_request(packet_info *pinfo, tvbuff_t *tvb, gint offset, proto_tree *tree) {
guint8 type;
guint16 name_length = 0;
const guint8 *name = NULL;
proto_tree_add_item(tree, hf_epmd_len, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
type = tvb_get_guint8(tvb, offset);
proto_tree_add_item(tree, hf_epmd_type, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
col_add_str(pinfo->cinfo, COL_INFO, val_to_str(type, VALS(message_types), "unknown (0x%02X)"));
switch (type) {
case EPMD_ALIVE2_REQ:
proto_tree_add_item(tree, hf_epmd_port_no, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(tree, hf_epmd_node_type, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(tree, hf_epmd_protocol, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(tree, hf_epmd_dist_high, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(tree, hf_epmd_dist_low, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
name_length = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(tree, hf_epmd_name_len, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item_ret_string(tree, hf_epmd_name, tvb, offset + 2, name_length, ENC_ASCII|ENC_NA, pinfo->pool, &name);
offset += 2 + name_length;
if (tvb_reported_length_remaining(tvb, offset) >= 2) {
guint16 elen=0;
elen = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(tree, hf_epmd_elen, tvb, offset, 2, ENC_BIG_ENDIAN);
if (elen > 0)
proto_tree_add_item(tree, hf_epmd_edata, tvb, offset + 2, elen, ENC_NA);
/*offset += 2 + elen;*/
}
break;
case EPMD_PORT_REQ:
case EPMD_PORT2_REQ:
name_length = tvb_captured_length_remaining(tvb, offset);
proto_tree_add_item_ret_string(tree, hf_epmd_name, tvb, offset, name_length, ENC_ASCII|ENC_NA, pinfo->pool, &name);
break;
case EPMD_ALIVE_REQ:
proto_tree_add_item(tree, hf_epmd_port_no, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
name_length = tvb_captured_length_remaining(tvb, offset);
proto_tree_add_item_ret_string(tree, hf_epmd_name, tvb, offset, name_length, ENC_ASCII|ENC_NA, pinfo->pool, &name);
break;
case EPMD_NAMES_REQ:
break;
}
if (name) {
col_append_fstr(pinfo->cinfo, COL_INFO, " %s", name);
}
}
static void
dissect_epmd_response_names(packet_info *pinfo _U_, tvbuff_t *tvb, gint offset, proto_tree *tree) {
proto_tree_add_item(tree, hf_epmd_port_no, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(tree, hf_epmd_names, tvb, offset, -1, ENC_NA);
}
static int
dissect_epmd_response(packet_info *pinfo, tvbuff_t *tvb, gint offset, proto_tree *tree) {
guint8 type, result;
guint32 port;
guint16 name_length = 0;
const guint8 *name = NULL;
conversation_t *conv = NULL;
port = tvb_get_ntohl(tvb, offset);
if (port == EPMD_PORT) {
dissect_epmd_response_names(pinfo, tvb, offset, tree);
return 0;
}
type = tvb_get_guint8(tvb, offset);
proto_tree_add_item(tree, hf_epmd_type, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
col_add_str(pinfo->cinfo, COL_INFO, val_to_str(type, VALS(message_types), "unknown (0x%02X)"));
switch (type) {
case EPMD_ALIVE_OK_RESP:
case EPMD_ALIVE2_RESP:
result = tvb_get_guint8(tvb, offset);
proto_tree_add_item(tree, hf_epmd_result, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(tree, hf_epmd_creation, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
if (!result) {
col_append_str(pinfo->cinfo, COL_INFO, " OK");
} else {
col_append_fstr(pinfo->cinfo, COL_INFO, " ERROR 0x%02X", result);
}
break;
case EPMD_PORT2_RESP:
result = tvb_get_guint8(tvb, offset);
proto_tree_add_item(tree, hf_epmd_result, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
if (!result) {
col_append_str(pinfo->cinfo, COL_INFO, " OK");
} else {
col_append_fstr(pinfo->cinfo, COL_INFO, " ERROR 0x%02X", result);
break;
}
port = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(tree, hf_epmd_port_no, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(tree, hf_epmd_node_type, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(tree, hf_epmd_protocol, tvb, offset, 1, ENC_BIG_ENDIAN);
offset++;
proto_tree_add_item(tree, hf_epmd_dist_high, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
proto_tree_add_item(tree, hf_epmd_dist_low, tvb, offset, 2, ENC_BIG_ENDIAN);
offset += 2;
name_length = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(tree, hf_epmd_name_len, tvb, offset, 2, ENC_BIG_ENDIAN);
proto_tree_add_item_ret_string(tree, hf_epmd_name, tvb, offset + 2, name_length, ENC_ASCII|ENC_NA, pinfo->pool, &name);
offset += 2 + name_length;
if (tvb_reported_length_remaining(tvb, offset) >= 2) {
guint16 elen=0;
elen = tvb_get_ntohs(tvb, offset);
proto_tree_add_item(tree, hf_epmd_elen, tvb, offset, 2, ENC_BIG_ENDIAN);
if (elen > 0)
proto_tree_add_item(tree, hf_epmd_edata, tvb, offset + 2, elen, ENC_NA);
offset += 2 + elen;
}
col_append_fstr(pinfo->cinfo, COL_INFO, " %s port=%d", name, port);
if (!pinfo->fd->visited) {
conv = conversation_new(pinfo->num, &pinfo->src, &pinfo->dst, CONVERSATION_TCP, port, 0, NO_PORT2);
conversation_set_dissector(conv, edp_handle);
}
break;
}
return offset;
}
static gboolean
check_epmd(tvbuff_t *tvb) {
guint8 type;
/* simple heuristic:
*
* just check if the type is one of the EPMD
* command types
*
* It's possible to start checking lengths but imho that
* doesn't bring very much.
*/
if (tvb_captured_length(tvb) < 3)
return (FALSE);
type = tvb_get_guint8(tvb, 0);
switch (type) {
case EPMD_ALIVE_OK_RESP:
case EPMD_ALIVE2_RESP:
case EPMD_PORT2_RESP:
return (TRUE);
default:
break;
}
type = tvb_get_guint8(tvb, 2);
switch (type) {
case EPMD_ALIVE_REQ:
case EPMD_ALIVE2_REQ:
case EPMD_PORT_REQ:
case EPMD_PORT2_REQ:
case EPMD_NAMES_REQ:
return (TRUE);
default:
break;
}
return (FALSE);
}
static int
dissect_epmd(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) {
proto_tree *epmd_tree;
proto_item *ti;
if (!check_epmd(tvb))
return (0);
col_set_str(pinfo->cinfo, COL_PROTOCOL, PSNAME);
ti = proto_tree_add_item(tree, proto_epmd, tvb, 0, -1, ENC_NA);
epmd_tree = proto_item_add_subtree(ti, ett_epmd);
if (pinfo->match_uint == pinfo->destport) {
dissect_epmd_request(pinfo, tvb, 0, epmd_tree);
} else {
dissect_epmd_response(pinfo, tvb, 0, epmd_tree);
}
return (tvb_captured_length(tvb));
}
void
proto_register_epmd(void)
{
static hf_register_info hf[] = {
{ &hf_epmd_len,
{ "Length", "epmd.len",
FT_UINT16, BASE_DEC, NULL, 0x0,
"Message Length", HFILL }},
{ &hf_epmd_type,
{ "Type", "epmd.type",
FT_UINT8, BASE_DEC, VALS(message_types), 0x0,
"Message Type", HFILL }},
{ &hf_epmd_result,
{ "Result", "epmd.result",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_epmd_port_no,
{ "Port No", "epmd.port_no",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_epmd_node_type,
{ "Node Type", "epmd.node_type",
FT_UINT8, BASE_DEC, VALS(node_type_vals), 0x0,
NULL, HFILL }},
{ &hf_epmd_protocol,
{ "Protocol", "epmd.protocol",
FT_UINT8, BASE_DEC, VALS(protocol_vals), 0x0,
NULL, HFILL }},
{ &hf_epmd_creation,
{ "Creation", "epmd.creation",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_epmd_dist_high,
{ "Highest Version", "epmd.dist_high",
FT_UINT16, BASE_DEC, VALS(epmd_version_vals), 0x0,
NULL, HFILL }},
{ &hf_epmd_dist_low,
{ "Lowest Version", "epmd.dist_low",
FT_UINT16, BASE_DEC, VALS(epmd_version_vals), 0x0,
NULL, HFILL }},
{ &hf_epmd_name_len,
{ "Name Length", "epmd.name_len",
FT_UINT16, BASE_DEC, NULL, 0x0,
NULL, HFILL }},
{ &hf_epmd_name,
{ "Node Name", "epmd.name",
FT_STRING, BASE_NONE, NULL, 0x0,
NULL, HFILL }},
{ &hf_epmd_elen,
{ "Elen", "epmd.elen",
FT_UINT16, BASE_DEC, NULL, 0x0,
"Extra Length", HFILL }},
{ &hf_epmd_edata,
{ "Edata", "epmd.edata",
FT_BYTES, BASE_NONE, NULL, 0x0,
"Extra Data", HFILL }},
{ &hf_epmd_names,
{ "Names", "epmd.names",
FT_BYTES, BASE_NONE, NULL, 0x0,
"List of names", HFILL }}
};
static gint *ett[] = {
&ett_epmd,
};
proto_epmd = proto_register_protocol(PNAME, PSNAME, PFNAME);
proto_register_field_array(proto_epmd, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
epmd_handle = register_dissector(PFNAME, dissect_epmd, proto_epmd);
}
void
proto_reg_handoff_epmd(void) {
edp_handle = find_dissector("erldp");
dissector_add_uint_with_preference("tcp.port", EPMD_PORT, epmd_handle);
}
/*
* Editor modelines - https://www.wireshark.org/tools/modelines.html
*
* Local variables:
* c-basic-offset: 4
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* vi: set shiftwidth=4 tabstop=8 expandtab:
* :indentSize=4:tabSize=8:noTabs=true:
*/
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