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/* packet-fc00.c
* Routines for fc00/cjdns dissection
* Copyright 2015, Emery Hemingway <emery@v36.spacet>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
/*
* https://github.com/hyperboria/cjdns
*/
#include <config.h>
#include <epan/expert.h>
#include <epan/packet.h>
#include <wsutil/base32.h>
/* Prototypes */
/* (Required to prevent [-Wmissing-prototypes] warnings */
void proto_reg_handoff_fc00(void);
void proto_register_fc00(void);
static dissector_handle_t fc00_handle;
/* Initialize the protocol and registered fields */
static int proto_fc00;
static int hf_fc00_session_state;
static int hf_fc00_session_nonce;
static int hf_fc00_auth_challenge;
static int hf_fc00_auth_type;
static int hf_fc00_auth_hash_code;
static int hf_fc00_auth_poly;
static int hf_fc00_auth_derivations;
static int hf_fc00_auth_additional;
static int hf_fc00_random_nonce;
static int hf_fc00_public_key;
static int hf_fc00_ip_address;
static int hf_fc00_authenticator;
static int hf_fc00_temp_publicy_key;
static int hf_fc00_payload;
/* Cjdns constants */
#define SESSION_STATE_OFF 0
#define SESSION_STATE_LEN 4
#define CHALLENGE_OFF 4
#define CHALLENGE_LEN 12
#define NONCE_OFF 16
#define NONCE_LEN 24
#define PUBLIC_KEY_OFF 40
#define PUBLIC_KEY_LEN 32
#define POLY_AUTH_OFF 72
#define POLY_AUTH_LEN 16
#define TEMP_KEY_OFF 88
#define TEMP_KEY_LEN 32
#define CRYPTO_HEADER_LEN 120
/* Initialize the subtree pointers */
static int ett_fc00;
static int ett_fc00_auth;
static int ett_fc00_key;
static const value_string session_states[] = {
{ UINT32_MAX, "Connect To Me" },
{ 0, "Hello" },
{ 1, "Hello" },
{ 2, "repeated Hello" },
{ 3, "Key" },
{ 4, "repeated Key" },
{ 0, NULL }
};
/* Code to actually dissect the packets */
static int
dissect_cryptoauth(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
uint32_t session_state;
proto_item *ti = NULL;
proto_tree *fc00_tree = NULL;
unsigned payload_len = 0;
col_set_str(pinfo->cinfo, COL_PROTOCOL, "fc00");
col_clear(pinfo->cinfo, COL_INFO);
session_state = tvb_get_ntohl(tvb, SESSION_STATE_OFF);
if ((session_state > 3) && (session_state < UINT32_MAX)) {
ti = proto_tree_add_item(tree, proto_fc00, tvb, 0, SESSION_STATE_LEN, ENC_NA);
fc00_tree = proto_item_add_subtree(ti, ett_fc00);
proto_tree_add_item(fc00_tree, hf_fc00_session_nonce, tvb,
SESSION_STATE_OFF, SESSION_STATE_LEN, ENC_BIG_ENDIAN);
payload_len = tvb_reported_length(tvb)-SESSION_STATE_LEN;
proto_tree_add_item(fc00_tree, hf_fc00_payload, tvb,
SESSION_STATE_LEN, payload_len, ENC_NA);
return SESSION_STATE_LEN;
}
ti = proto_tree_add_item(tree, proto_fc00, tvb, 0, 120, ENC_NA);
fc00_tree = proto_item_add_subtree(ti, ett_fc00);
proto_tree_add_item(fc00_tree, hf_fc00_session_state, tvb,
SESSION_STATE_OFF, SESSION_STATE_LEN, ENC_NA);
ti = proto_tree_add_item(fc00_tree, hf_fc00_auth_challenge, tvb,
CHALLENGE_OFF, CHALLENGE_LEN, ENC_NA);
{
proto_tree *auth_tree = proto_item_add_subtree(ti, ett_fc00_auth);
proto_tree_add_item(auth_tree, hf_fc00_auth_type, tvb, CHALLENGE_OFF, 1, ENC_NA);
proto_tree_add_item(auth_tree, hf_fc00_auth_hash_code, tvb, CHALLENGE_OFF+1, 7, ENC_NA);
proto_tree_add_item(auth_tree, hf_fc00_auth_poly, tvb, CHALLENGE_OFF+8, 1, ENC_NA);
proto_tree_add_item(auth_tree, hf_fc00_auth_derivations, tvb, CHALLENGE_OFF+8, 2, ENC_NA);
proto_tree_add_item(auth_tree, hf_fc00_auth_additional, tvb, CHALLENGE_OFF+10, 2, ENC_NA);
}
proto_tree_add_item(fc00_tree, hf_fc00_random_nonce, tvb,
NONCE_OFF, NONCE_LEN, ENC_NA);
if (fc00_tree)
{
GChecksum *hash = g_checksum_new(G_CHECKSUM_SHA512);
size_t digest_len = g_checksum_type_get_length(G_CHECKSUM_SHA512);
proto_tree *key_tree;
uint8_t *raw_key = (uint8_t*)wmem_alloc(pinfo->pool, PUBLIC_KEY_LEN);
char *encoded_key = (char*)wmem_alloc(pinfo->pool, 53);
uint8_t *ip_buf = (uint8_t*)wmem_alloc(pinfo->pool, digest_len);
tvb_memcpy(tvb, raw_key, PUBLIC_KEY_OFF, PUBLIC_KEY_LEN);
ws_base32_decode((uint8_t*)encoded_key, 53, raw_key, PUBLIC_KEY_LEN);
g_checksum_update(hash, (unsigned char*)raw_key, PUBLIC_KEY_LEN);
g_checksum_get_digest(hash, ip_buf, &digest_len);
g_checksum_free(hash);
hash = g_checksum_new(G_CHECKSUM_SHA512);
g_checksum_update(hash, (unsigned char*)ip_buf, digest_len);
g_checksum_get_digest(hash, ip_buf, &digest_len);
g_checksum_free(hash);
ti = proto_tree_add_none_format(fc00_tree, hf_fc00_public_key, tvb, PUBLIC_KEY_OFF, PUBLIC_KEY_LEN, "Public Key: %s.k", encoded_key);
key_tree = proto_item_add_subtree(ti, ett_fc00_key);
proto_tree_add_ipv6(key_tree, hf_fc00_ip_address, tvb, PUBLIC_KEY_OFF, PUBLIC_KEY_LEN, (ws_in6_addr*)ip_buf);
}
proto_tree_add_item(fc00_tree, hf_fc00_authenticator, tvb,
POLY_AUTH_OFF, POLY_AUTH_LEN, ENC_NA);
proto_tree_add_item(fc00_tree, hf_fc00_temp_publicy_key, tvb,
TEMP_KEY_OFF, TEMP_KEY_LEN, ENC_NA);
payload_len = tvb_reported_length(tvb)-(TEMP_KEY_OFF+TEMP_KEY_LEN);
proto_tree_add_item(fc00_tree, hf_fc00_payload, tvb,
CRYPTO_HEADER_LEN, payload_len, ENC_NA);
return tvb_captured_length(tvb);
}
/* Register the protocol with Wireshark.
*/
void
proto_register_fc00(void)
{
static hf_register_info hf[] = {
{ &hf_fc00_session_state,
{ "Session State", "fc00.session_state",
FT_UINT32, BASE_DEC, VALS(session_states), 0x0,
NULL, HFILL }
},
{ &hf_fc00_session_nonce,
{ "Session Nonce", "fc00.session_nonce",
FT_UINT32, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_auth_challenge,
{ "Auth Challenge", "fc00.auth_challenge",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_auth_type,
{ "Auth Type", "fc00.auth_challenge.type",
FT_UINT8, BASE_DEC, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_auth_hash_code,
{ "Auth Hash Code", "fc00.auth_challenge.hash_code",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_auth_poly,
{ "Poly1305 Authentication", "fc00.auth_challenge.poly1305",
FT_UINT8, BASE_DEC, NULL, 0x80,
NULL, HFILL }
},
{ &hf_fc00_auth_derivations,
{ "Auth Derivations", "fc00.auth_challenge.derivations",
FT_UINT16, BASE_DEC, NULL, 0x7F,
NULL, HFILL }
},
{ &hf_fc00_auth_additional,
{ "Auth Additional", "fc00.auth_challenge.additional",
FT_UINT16, BASE_HEX, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_random_nonce,
{ "Random Nonce", "fc00.random_nonce",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_public_key,
{ "Permanent Public Key", "fc00.public_key",
FT_NONE, BASE_NONE, NULL, 0x0,
"Base32 encoded public key", HFILL }
},
{ &hf_fc00_ip_address,
{ "IPv6 Address", "fc00.ip",
FT_IPv6, BASE_NONE, NULL, 0x0,
"Double SHA256 hash of public key", HFILL }
},
{ &hf_fc00_authenticator,
{ "Poly1305 Authenticator", "fc00.authenticator",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_temp_publicy_key,
{ "Encrypted/Authenticated Temporary Public Key",
"fc00.temp_key",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
},
{ &hf_fc00_payload,
{ "Encrypted Payload", "fc00.payload",
FT_BYTES, BASE_NONE, NULL, 0x0,
NULL, HFILL }
}
};
static int *ett[] = {
&ett_fc00,
&ett_fc00_auth,
&ett_fc00_key
};
proto_fc00 = proto_register_protocol("Fc00 CryptoAuth", "Fc00", "fc00");
proto_register_field_array(proto_fc00, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
fc00_handle = register_dissector("fc00", dissect_cryptoauth, proto_fc00);
}
void
proto_reg_handoff_fc00(void)
{
dissector_add_for_decode_as_with_preference("udp.port", fc00_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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