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Merged
vlvkobal merged 1 commit into from
Nov 6, 2025
Merged

Update JA4D implementation #267

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154 changes: 139 additions & 15 deletions wireshark/source/packet-ja4.c
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -149,10 +149,14 @@ static const char *interesting_hfids[] = {
"quic.long.packet_type",
"dhcp.option.dhcp",
"dhcp.option.dhcp_max_message_size",
"dhcp.option.requested_ip_address",
"dhcp.fqdn.name",
"dhcp.option.type",
"dhcp.option.request_list_item",
"dhcpv6.msgtype",
"dhcpv6.duid.bytes",
"dhcpv6.iata",
"dhcpv6.client_domain",
"dhcpv6.option.type",
"dhcpv6.requested_option_code",
};
Expand Down Expand Up @@ -201,8 +205,10 @@ typedef struct {

typedef struct {
char proto;
uint32_t type;
wmem_strbuf_t *type;
wmem_strbuf_t *size;
char ip;
char fqdn;
wmem_strbuf_t *options;
wmem_strbuf_t *request_list;
} ja4d_info_t;
Expand Down Expand Up @@ -683,17 +689,20 @@ static char *ja4t(wmem_allocator_t *scope, ja4t_info_t *data, conn_info_t *conn)

static char *ja4d(wmem_allocator_t *scope, ja4d_info_t *data) {
wmem_strbuf_t *display = wmem_strbuf_new(scope, "");
if (wmem_strbuf_get_len(data->type) == 0)
wmem_strbuf_append_printf(data->type, "00000");
if (wmem_strbuf_get_len(data->size) == 0)
wmem_strbuf_append_printf(data->size, "00");
wmem_strbuf_append_printf(data->size, "0000");
if (wmem_strbuf_get_len(data->options) == 0)
wmem_strbuf_append_printf(data->options, "00");
if (wmem_strbuf_get_len(data->request_list) == 0)
wmem_strbuf_append_printf(data->request_list, "00");
wmem_strbuf_append_printf(
display, "%c-%d-%s_%s_%s",
data->proto,
data->type,
display, "%s%s%c%c_%s_%s",
wmem_strbuf_get_str(data->type),
wmem_strbuf_get_str(data->size),
data->ip,
data->fqdn,
wmem_strbuf_get_str(data->options),
wmem_strbuf_get_str(data->request_list)
);
Expand Down Expand Up @@ -780,6 +789,83 @@ static void set_ja4_ciphers(proto_tree *tree, ja4_info_t *data) {
}
}

static const char *get_dhcp_type_code(unsigned type) {
// Index is the DHCP type number (0 unused)
static const char *map[] = {
NULL, // 0
"disco", // 1
"offer", // 2
"reqst", // 3
"decln", // 4
"dpack", // 5
"dpnak", // 6
"relse", // 7
"infor", // 8
"frenw", // 9
"lqery", // 10
"lunas", // 11
"lunkn", // 12
"lactv", // 13
"blklq", // 14
"lqdon", // 15
"actlq", // 16
"lqsta", // 17
"dhtls" // 18
};
if (type < G_N_ELEMENTS(map)) {
return map[type];
}
return NULL;
}

static const char *get_dhcpv6_type_code(unsigned type) {
// Index is the DHCPv6 message type number (0 unused)
static const char *map[] = {
NULL, // 0
"solct", // 1
"advrt", // 2
"reqst", // 3
"confm", // 4
"renew", // 5
"rebnd", // 6
"reply", // 7
"relse", // 8
"decln", // 9
"recon", // 10
"inreq", // 11
"rlayf", // 12
"rlayr", // 13
"query", // 14
"qrply", // 15
"qdone", // 16
"qdata", // 17
"rereq", // 18
"rrply", // 19
"v4qry", // 20
"v4res", // 21
"acqry", // 22
"sttls", // 23
"bdudp", // 24
"brply", // 25
"poreq", // 26
"pores", // 27
"urqst", // 28
"ureqa", // 29
"udone", // 30
"conne", // 31
"connr", // 32
"dconn", // 33
"state", // 34
"conta", // 35
"arinf", // 36
"arrep" // 37
};
if (type < G_N_ELEMENTS(map)) {
return map[type];
}
return NULL;
}

static int dissect_ja4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *dummy _U_) {
uint32_t handshake_type = 0;
bool alpn_visited = false;
Expand Down Expand Up @@ -844,8 +930,10 @@ static int dissect_ja4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void

ja4d_info_t ja4d_data;
ja4d_data.proto = 0;
ja4d_data.type = 0;
ja4d_data.type = wmem_strbuf_new(pinfo->pool, "");
ja4d_data.size = wmem_strbuf_new(pinfo->pool, "");
ja4d_data.ip = 'n';
ja4d_data.fqdn = 'n';
ja4d_data.options = wmem_strbuf_new(pinfo->pool, "");
ja4d_data.request_list = wmem_strbuf_new(pinfo->pool, "");

Expand Down Expand Up @@ -1380,12 +1468,30 @@ static int dissect_ja4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void
// DHCPv4
if (strcmp(field->hfinfo->abbrev, "dhcp.option.dhcp") == 0) {
ja4d_data.proto = '4';
ja4d_data.type = fvalue_get_uinteger(get_value_ptr(field));
unsigned dhcp_type = fvalue_get_uinteger(get_value_ptr(field));
const char *type_code = get_dhcp_type_code(dhcp_type);
if (type_code != NULL) {
wmem_strbuf_append(ja4d_data.type, type_code);
} else {
wmem_strbuf_append_printf(ja4d_data.type, "%05u", dhcp_type);
}
}
if (strcmp(field->hfinfo->abbrev, "dhcp.option.dhcp_max_message_size") == 0) {
wmem_strbuf_append_printf(
ja4d_data.size, "%d", fvalue_get_uinteger(get_value_ptr(field))
);
if (fvalue_get_uinteger(get_value_ptr(field)) < 9999) {
wmem_strbuf_append_printf(
ja4d_data.size, "%04d", fvalue_get_uinteger(get_value_ptr(field))
);
} else {
wmem_strbuf_append_printf(
ja4d_data.size, "9999"
);
}
}
if (strcmp(field->hfinfo->abbrev, "dhcp.option.requested_ip_address") == 0) {
ja4d_data.ip = 'i';
}
if (strcmp(field->hfinfo->abbrev, "dhcp.fqdn.name") == 0) {
ja4d_data.fqdn = 'd';
}
if (strcmp(field->hfinfo->abbrev, "dhcp.option.type") == 0) {
unsigned val = fvalue_get_uinteger(get_value_ptr(field));
Expand All @@ -1402,14 +1508,32 @@ static int dissect_ja4(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void
// DHCPv6
if (strcmp(field->hfinfo->abbrev, "dhcpv6.msgtype") == 0) {
ja4d_data.proto = '6';
ja4d_data.type = fvalue_get_uinteger(get_value_ptr(field));
unsigned dhcpv6_type = fvalue_get_uinteger(get_value_ptr(field));
const char *type_code = get_dhcpv6_type_code(dhcpv6_type);
if (type_code != NULL) {
wmem_strbuf_append(ja4d_data.type, type_code);
} else {
wmem_strbuf_append_printf(ja4d_data.type, "%05u", dhcpv6_type);
}
}
if (strcmp(field->hfinfo->abbrev, "dhcpv6.duid.bytes") == 0 &&
wmem_strbuf_get_len(ja4d_data.size) == 0 &&
dhcpv6_option_type_1_exists == true) {
wmem_strbuf_append_printf(
ja4d_data.size, "%d", field->length
);
if (field->length < 9999) {
wmem_strbuf_append_printf(
ja4d_data.size, "%04d", field->length
);
} else {
wmem_strbuf_append_printf(
ja4d_data.size, "9999"
);
}
}
if (strcmp(field->hfinfo->abbrev, "dhcpv6.iata") == 0) {
ja4d_data.ip = 'i';
}
if (strcmp(field->hfinfo->abbrev, "dhcpv6.client_domain") == 0) {
ja4d_data.fqdn = 'd';
}
if (strcmp(field->hfinfo->abbrev, "dhcpv6.option.type") == 0) {
unsigned val = fvalue_get_uinteger(get_value_ptr(field));
Expand Down Expand Up @@ -1535,7 +1659,7 @@ static int frame_tapdata;

static void init_globals(void) {
GArray *wanted_hfids = g_array_new(false, false, (unsigned)sizeof(int));
for (int i = 0; i < array_length(interesting_hfids); i++) {
for (size_t i = 0; i < array_length(interesting_hfids); i++) {
int id = proto_registrar_get_id_byname(interesting_hfids[i]);
if (id != -1) {
g_array_append_val(wanted_hfids, id);
Expand Down
8 changes: 4 additions & 4 deletions wireshark/test/testdata/dhcp.pcapng.json
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
"1"
],
"ja4.ja4d": [
"4-1-00_61-50-55_1-3-6-42"
"disco0000in_61-50-55_1-3-6-42"
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Collaborator

@J0eJ0h J0eJ0h Nov 7, 2025

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I'm working on the Zeek version and the current spec wants 50 and 81 excluded from listed options as they are covered by the two characters in the first part.

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@vlvkobal vlvkobal Nov 8, 2025

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Thanks, @J0eJ0h - that slipped past me. Will fix it.

]
}
}
Expand All @@ -22,7 +22,7 @@
"2"
],
"ja4.ja4d": [
"4-2-00_1-58-59-51-54_00"
"offer0000nn_1-58-59-51-54_00"
]
}
}
Expand All @@ -36,7 +36,7 @@
"3"
],
"ja4.ja4d": [
"4-3-00_61-50-54-55_1-3-6-42"
"reqst0000in_61-50-54-55_1-3-6-42"
]
}
}
Expand All @@ -50,7 +50,7 @@
"4"
],
"ja4.ja4d": [
"4-5-00_58-59-51-54-1_00"
"dpack0000nn_58-59-51-54-1_00"
]
}
}
Expand Down
12 changes: 6 additions & 6 deletions wireshark/test/testdata/dhcpv6.pcap.json
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@
"2"
],
"ja4.ja4d": [
"6-1-14_1-6-8-25_23-24"
"solct0014nn_1-6-8-25_23-24"
]
}
}
Expand All @@ -22,7 +22,7 @@
"5"
],
"ja4.ja4d": [
"6-2-14_25-26-1-2_00"
"advrt0014nn_25-26-1-2_00"
]
}
}
Expand All @@ -36,7 +36,7 @@
"7"
],
"ja4.ja4d": [
"6-3-14_1-2-6-8-25-26_23-24"
"reqst0014nn_1-2-6-8-25-26_23-24"
]
}
}
Expand All @@ -50,7 +50,7 @@
"8"
],
"ja4.ja4d": [
"6-7-14_25-26-1-2_00"
"reply0014nn_25-26-1-2_00"
]
}
}
Expand All @@ -64,7 +64,7 @@
"11"
],
"ja4.ja4d": [
"6-8-14_1-2-6-8-25-26_23-24"
"relse0014nn_1-2-6-8-25-26_23-24"
]
}
}
Expand All @@ -78,7 +78,7 @@
"12"
],
"ja4.ja4d": [
"6-7-14_1-2-13_00"
"reply0014nn_1-2-13_00"
]
}
}
Expand Down