Add an NFC parser for the San Francisco Bay Area "Clipper" transit card. (#3344)

* Add an NFC parser for the San Francisco Bay Area "Clipper" transit card.

* Add more agencies and stations, decode vehicle ids, refactor.

Add more agencies and station names using data from local research
and:

* Metrodroid project (GPLv3): https://github.com/metrodroid/metrodroid
* Farebot (GPLv3): https://github.com/codebutler/farebot

---------

Co-authored-by: gornekich <n.gorbadey@gmail.com>
Co-authored-by: hedger <hedger@users.noreply.github.com>
This commit is contained in:
Jeremy Cooper 2024-02-06 09:47:44 -08:00 committed by GitHub
parent 2c784d3fea
commit a83e421d71
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
2 changed files with 630 additions and 0 deletions

View file

@ -110,6 +110,15 @@ App(
sources=["plugins/supported_cards/umarsh.c"],
)
App(
appid="clipper_parser",
apptype=FlipperAppType.PLUGIN,
entry_point="clipper_plugin_ep",
targets=["f7"],
requires=["nfc"],
sources=["plugins/supported_cards/clipper.c"],
)
App(
appid="hid_parser",
apptype=FlipperAppType.PLUGIN,

View file

@ -0,0 +1,621 @@
/*
* clipper.c - Parser for Clipper cards (San Francisco, California).
*
* Based on research, some of which dates to 2007!
*
* Copyright 2024 Jeremy Cooper <jeremy.gthb@baymoo.org>
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "nfc_supported_card_plugin.h"
#include <flipper_application/flipper_application.h>
#include <lib/nfc/protocols/mf_desfire/mf_desfire.h>
#include <lib/nfc/helpers/nfc_util.h>
#include <applications/services/locale/locale.h>
#include <furi_hal_rtc.h>
#include <inttypes.h>
//
// Table of application ids observed in the wild, and their sources.
//
static const struct {
const MfDesfireApplicationId app;
const char* type;
} clipper_types[] = {
// Application advertised on classic, plastic cards.
{.app = {.data = {0x90, 0x11, 0xf2}}, .type = "Card"},
// Application advertised on a mobile device.
{.app = {.data = {0x91, 0x11, 0xf2}}, .type = "Mobile Device"},
};
static const size_t kNumCardTypes = sizeof(clipper_types) / sizeof(clipper_types[0]);
struct IdMapping_struct {
uint16_t id;
const char* name;
};
typedef struct IdMapping_struct IdMapping;
#define COUNT(_array) sizeof(_array) / sizeof(_array[0])
//
// Known transportation agencies and their identifiers.
//
static const IdMapping agency_names[] = {
{.id = 0x0001, .name = "AC Transit"},
{.id = 0x0004, .name = "BART"},
{.id = 0x0006, .name = "Caltrain"},
{.id = 0x0008, .name = "CCTA"},
{.id = 0x000b, .name = "GGT"},
{.id = 0x000f, .name = "SamTrans"},
{.id = 0x0011, .name = "VTA"},
{.id = 0x0012, .name = "Muni"},
{.id = 0x0019, .name = "GG Ferry"},
{.id = 0x001b, .name = "SF Bay Ferry"},
};
static const size_t kNumAgencies = COUNT(agency_names);
//
// Known station names for various agencies.
//
static const IdMapping bart_zones[] = {
{.id = 0x0001, .name = "Colma"},
{.id = 0x0002, .name = "Daly City"},
{.id = 0x0003, .name = "Balboa Park"},
{.id = 0x0004, .name = "Glen Park"},
{.id = 0x0005, .name = "24th St Mission"},
{.id = 0x0006, .name = "16th St Mission"},
{.id = 0x0007, .name = "Civic Center/UN Plaza"},
{.id = 0x0008, .name = "Powell St"},
{.id = 0x0009, .name = "Montgomery St"},
{.id = 0x000a, .name = "Embarcadero"},
{.id = 0x000b, .name = "West Oakland"},
{.id = 0x000c, .name = "12th St/Oakland City Center"},
{.id = 0x000d, .name = "19th St/Oakland"},
{.id = 0x000e, .name = "MacArthur"},
{.id = 0x000f, .name = "Rockridge"},
{.id = 0x0010, .name = "Orinda"},
{.id = 0x0011, .name = "Lafayette"},
{.id = 0x0012, .name = "Walnut Creek"},
{.id = 0x0013, .name = "Pleasant Hill/Contra Costa Centre"},
{.id = 0x0014, .name = "Concord"},
{.id = 0x0015, .name = "North Concord/Martinez"},
{.id = 0x0016, .name = "Pittsburg/Bay Point"},
{.id = 0x0017, .name = "Ashby"},
{.id = 0x0018, .name = "Downtown Berkeley"},
{.id = 0x0019, .name = "North Berkeley"},
{.id = 0x001a, .name = "El Cerrito Plaza"},
{.id = 0x001b, .name = "El Cerrito Del Norte"},
{.id = 0x001c, .name = "Richmond"},
{.id = 0x001d, .name = "Lake Merrit"},
{.id = 0x001e, .name = "Fruitvale"},
{.id = 0x001f, .name = "Coliseum"},
{.id = 0x0021, .name = "San Leandro"},
{.id = 0x0022, .name = "Hayward"},
{.id = 0x0023, .name = "South Hayward"},
{.id = 0x0024, .name = "Union City"},
{.id = 0x0025, .name = "Fremont"},
{.id = 0x0026, .name = "Daly City(2)?"},
{.id = 0x0027, .name = "Dublin/Pleasanton"},
{.id = 0x0028, .name = "South San Francisco"},
{.id = 0x0029, .name = "San Bruno"},
{.id = 0x002a, .name = "SFO Airport"},
{.id = 0x002b, .name = "Millbrae"},
{.id = 0x002c, .name = "West Dublin/Pleasanton"},
{.id = 0x002d, .name = "OAK Airport"},
{.id = 0x002e, .name = "Warm Springs/South Fremont"},
};
static const size_t kNumBARTZones = COUNT(bart_zones);
static const IdMapping muni_zones[] = {
{.id = 0x0000, .name = "City Street"},
{.id = 0x0005, .name = "Embarcadero"},
{.id = 0x0006, .name = "Montgomery"},
{.id = 0x0007, .name = "Powell"},
{.id = 0x0008, .name = "Civic Center"},
{.id = 0x0009, .name = "Van Ness"}, // Guessed
{.id = 0x000a, .name = "Church"},
{.id = 0x000b, .name = "Castro"},
{.id = 0x000c, .name = "Forest Hill"}, // Guessed
{.id = 0x000d, .name = "West Portal"},
};
static const size_t kNumMUNIZones = COUNT(muni_zones);
static const IdMapping actransit_zones[] = {
{.id = 0x0000, .name = "City Street"},
};
static const size_t kNumACTransitZones = COUNT(actransit_zones);
//
// Full agency+zone mapping.
//
static const struct {
uint16_t agency_id;
const IdMapping* zone_map;
size_t zone_count;
} agency_zone_map[] = {
{.agency_id = 0x0001, .zone_map = actransit_zones, .zone_count = kNumACTransitZones},
{.agency_id = 0x0004, .zone_map = bart_zones, .zone_count = kNumBARTZones},
{.agency_id = 0x0012, .zone_map = muni_zones, .zone_count = kNumMUNIZones}};
static const size_t kNumAgencyZoneMaps = COUNT(agency_zone_map);
// File ids of important files on the card.
static const MfDesfireFileId clipper_ecash_file_id = 2;
static const MfDesfireFileId clipper_histidx_file_id = 6;
static const MfDesfireFileId clipper_identity_file_id = 8;
static const MfDesfireFileId clipper_history_file_id = 14;
struct ClipperCardInfo_struct {
uint32_t serial_number;
uint16_t counter;
uint16_t last_txn_id;
uint32_t last_updated_tm_1900;
uint16_t last_terminal_id;
int16_t balance_cents;
};
typedef struct ClipperCardInfo_struct ClipperCardInfo;
// Forward declarations for helper functions.
static void furi_string_cat_timestamp(
FuriString* str,
const char* date_hdr,
const char* time_hdr,
uint32_t tmst_1900);
static void epoch_1900_datetime_to_furi(uint32_t seconds, FuriHalRtcDateTime* out);
static bool get_file_contents(
const MfDesfireApplication* app,
const MfDesfireFileId* id,
MfDesfireFileType type,
size_t min_size,
const uint8_t** out);
static bool decode_id_file(const uint8_t* ef8_data, ClipperCardInfo* info);
static bool decode_cash_file(const uint8_t* ef2_data, ClipperCardInfo* info);
static bool get_map_item(uint16_t id, const IdMapping* map, size_t sz, const char** out);
static bool get_agency_zone_name(uint16_t agency_id, uint16_t zone_id, const char** out);
static void
decode_usd(int16_t amount_cents, bool* out_is_negative, int16_t* out_usd, uint16_t* out_cents);
static bool dump_ride_history(
const uint8_t* index_file,
const uint8_t* history_file,
size_t len,
FuriString* parsed_data);
static bool dump_ride_event(const uint8_t* record, FuriString* parsed_data);
// Unmarshal a 32-bit integer, big endian, unsigned
static inline uint32_t get_u32be(const uint8_t* field) {
return nfc_util_bytes2num(field, 4);
}
// Unmarshal a 16-bit integer, big endian, unsigned
static uint16_t get_u16be(const uint8_t* field) {
return nfc_util_bytes2num(field, 2);
}
// Unmarshal a 16-bit integer, big endian, signed, two's-complement
static int16_t get_i16be(const uint8_t* field) {
uint16_t raw = get_u16be(field);
if(raw > 0x7fff)
return -((uint32_t)0x10000 - raw);
else
return raw;
}
static bool clipper_parse(const NfcDevice* device, FuriString* parsed_data) {
furi_assert(device);
furi_assert(parsed_data);
bool parsed = false;
do {
const MfDesfireData* data = nfc_device_get_data(device, NfcProtocolMfDesfire);
const MfDesfireApplication* app = NULL;
const char* device_description = NULL;
for(size_t i = 0; i < kNumCardTypes; i++) {
app = mf_desfire_get_application(data, &clipper_types[i].app);
device_description = clipper_types[i].type;
if(app != NULL) break;
}
// If no matching application was found, abort this parser.
if(app == NULL) break;
ClipperCardInfo info;
const uint8_t* id_data;
if(!get_file_contents(
app, &clipper_identity_file_id, MfDesfireFileTypeStandard, 5, &id_data))
break;
if(!decode_id_file(id_data, &info)) break;
const uint8_t* cash_data;
if(!get_file_contents(app, &clipper_ecash_file_id, MfDesfireFileTypeBackup, 32, &cash_data))
break;
if(!decode_cash_file(cash_data, &info)) break;
int16_t balance_usd;
uint16_t balance_cents;
bool _balance_is_negative;
decode_usd(info.balance_cents, &_balance_is_negative, &balance_usd, &balance_cents);
furi_string_cat_printf(
parsed_data,
"\e#Clipper\n"
"Serial: %" PRIu32 "\n"
"Balance: $%d.%02u\n"
"Type: %s\n"
"\e#Last Update\n",
info.serial_number,
balance_usd,
balance_cents,
device_description);
if(info.last_updated_tm_1900 != 0)
furi_string_cat_timestamp(
parsed_data, "Date: ", "\nTime: ", info.last_updated_tm_1900);
else
furi_string_cat_str(parsed_data, "Never");
furi_string_cat_printf(
parsed_data,
"\nTerminal: 0x%04x\n"
"Transaction Id: %u\n"
"Counter: %u\n",
info.last_terminal_id,
info.last_txn_id,
info.counter);
const uint8_t *history_index, *history;
if(!get_file_contents(
app, &clipper_histidx_file_id, MfDesfireFileTypeBackup, 16, &history_index))
break;
if(!get_file_contents(
app, &clipper_history_file_id, MfDesfireFileTypeStandard, 512, &history))
break;
if(!dump_ride_history(history_index, history, 512, parsed_data)) break;
parsed = true;
} while(false);
return parsed;
}
static bool get_file_contents(
const MfDesfireApplication* app,
const MfDesfireFileId* id,
MfDesfireFileType type,
size_t min_size,
const uint8_t** out) {
const MfDesfireFileSettings* settings = mf_desfire_get_file_settings(app, id);
if(settings == NULL) return false;
if(settings->type != type) return false;
const MfDesfireFileData* file_data = mf_desfire_get_file_data(app, id);
if(file_data == NULL) return false;
if(simple_array_get_count(file_data->data) < min_size) return false;
*out = simple_array_cget_data(file_data->data);
return true;
}
static bool decode_id_file(const uint8_t* ef8_data, ClipperCardInfo* info) {
// Identity file (8)
//
// Byte view
//
// 0 1 2 3 4 5 6 7 8
// +----+----.----.----.----+----.----.----+
// 0x00 | uk | card_id | unknown |
// +----+----.----.----.----+----.----.----+
// 0x08 | unknown |
// +----.----.----.----.----.----.----.----+
// 0x10 ...
//
//
// Field Datatype Description
// ----- -------- -----------
// uk ?8?? Unknown, 8-bit byte
// card_id U32BE Card identifier
//
info->serial_number = nfc_util_bytes2num(&ef8_data[1], 4);
return true;
}
static bool decode_cash_file(const uint8_t* ef2_data, ClipperCardInfo* info) {
// ECash file (2)
//
// Byte view
//
// 0 1 2 3 4 5 6 7 8
// +----.----+----.----+----.----.----.----+
// 0x00 | unk00 | counter | timestamp_1900 |
// +----.----+----.----+----.----.----.----+
// 0x08 | term_id | unk01 |
// +----.----+----.----+----.----.----.----+
// 0x10 | txn_id | balance | unknown |
// +----.----+----.----+----.----.----.----+
// 0x18 | unknown |
// +---------------------------------------+
//
// Field Datatype Description
// ----- -------- -----------
// unk00 U8[2] Unknown bytes
// counter U16BE Unknown, appears to be a counter
// timestamp_1900 U32BE Timestamp of last transaction, in seconds
// since 1900-01-01 GMT.
// unk01 U8[6] Unknown bytes
// txn_id U16BE Id of last transaction.
// balance S16BE Card cash balance, in cents.
// Cards can obtain negative balances in this
// system, so balances are signed integers.
// Maximum card balance is therefore
// $327.67.
// unk02 U8[12] Unknown bytes.
//
info->counter = get_u16be(&ef2_data[2]);
info->last_updated_tm_1900 = get_u32be(&ef2_data[4]);
info->last_terminal_id = get_u16be(&ef2_data[8]);
info->last_txn_id = get_u16be(&ef2_data[0x10]);
info->balance_cents = get_i16be(&ef2_data[0x12]);
return true;
}
static bool dump_ride_history(
const uint8_t* index_file,
const uint8_t* history_file,
size_t len,
FuriString* parsed_data) {
static const size_t kRideRecordSize = 0x20;
for(size_t i = 0; i < 16; i++) {
uint8_t record_num = index_file[i];
if(record_num == 0xff) break;
size_t record_offset = record_num * kRideRecordSize;
if(record_offset + kRideRecordSize > len) break;
const uint8_t* record = &history_file[record_offset];
if(!dump_ride_event(record, parsed_data)) break;
}
return true;
}
static bool dump_ride_event(const uint8_t* record, FuriString* parsed_data) {
// Ride record
//
// 0 1 2 3 4 5 6 7 8
// +----+----+----.----+----.----+----.----+
// 0x00 |0x10| ? | agency | ? | fare |
// +----.----+----.----+----.----.----.----+
// 0x08 | ? | vehicle | time_on |
// +----.----.----.----+----.----+----.----+
// 0x10 | time_off | zone_on | zone_off|
// +----+----.----.----.----+----+----+----+
// 0x18 | ? | ? | ? | ? | ? |
// +----+----.----.----.----+----+----+----+
//
// Field Datatype Description
// ----- -------- -----------
// agency U16BE Transportation agency identifier.
// Known ids:
// 1 == AC Transit
// 4 == BART
// 18 == SF MUNI
// fare I16BE Fare deducted, in cents.
// vehicle U16BE Vehicle id (0 == not provided)
// time_on U32BE Boarding time, in seconds since 1900-01-01 GMT.
// time_off U32BE Off-boarding time, if present, in seconds
// since 1900-01-01 GMT. Set to zero if no offboard
// has been recorded.
// zone_on U16BE Id of boarding zone or station. Agency-specific.
// zone_off U16BE Id of offboarding zone or station. Agency-
// specific.
if(record[0] != 0x10) return false;
uint16_t agency_id = get_u16be(&record[2]);
if(agency_id == 0)
// Likely empty record. Skip.
return false;
const char* agency_name;
bool ok = get_map_item(agency_id, agency_names, kNumAgencies, &agency_name);
if(!ok) agency_name = "Unknown";
uint16_t vehicle_id = get_u16be(&record[0x0a]);
int16_t fare_raw_cents = get_i16be(&record[6]);
bool _fare_is_negative;
int16_t fare_usd;
uint16_t fare_cents;
decode_usd(fare_raw_cents, &_fare_is_negative, &fare_usd, &fare_cents);
uint32_t time_on_raw = get_u32be(&record[0x0c]);
uint32_t time_off_raw = get_u32be(&record[0x10]);
uint16_t zone_id_on = get_u16be(&record[0x14]);
uint16_t zone_id_off = get_u16be(&record[0x16]);
const char *zone_on, *zone_off;
if(!get_agency_zone_name(agency_id, zone_id_on, &zone_on)) {
zone_on = "Unknown";
}
if(!get_agency_zone_name(agency_id, zone_id_off, &zone_off)) {
zone_off = "Unknown";
}
furi_string_cat_str(parsed_data, "\e#Ride Record\n");
furi_string_cat_timestamp(parsed_data, "Date: ", "\nTime: ", time_on_raw);
furi_string_cat_printf(
parsed_data,
"\n"
"Fare: $%d.%02u\n"
"Agency: %s (%04x)\n"
"On: %s (%04x)\n",
fare_usd,
fare_cents,
agency_name,
agency_id,
zone_on,
zone_id_on);
if(vehicle_id != 0) {
furi_string_cat_printf(parsed_data, "Vehicle id: %d\n", vehicle_id);
}
if(time_off_raw != 0) {
furi_string_cat_printf(parsed_data, "Off: %s (%04x)\n", zone_off, zone_id_off);
furi_string_cat_timestamp(parsed_data, "Date Off: ", "\nTime Off: ", time_off_raw);
furi_string_cat_str(parsed_data, "\n");
}
return true;
}
static bool get_map_item(uint16_t id, const IdMapping* map, size_t sz, const char** out) {
for(size_t i = 0; i < sz; i++) {
if(map[i].id == id) {
*out = map[i].name;
return true;
}
}
return false;
}
static bool get_agency_zone_name(uint16_t agency_id, uint16_t zone_id, const char** out) {
for(size_t i = 0; i < kNumAgencyZoneMaps; i++) {
if(agency_zone_map[i].agency_id == agency_id) {
return get_map_item(
zone_id, agency_zone_map[i].zone_map, agency_zone_map[i].zone_count, out);
}
}
return false;
}
// Split a balance/fare amount from raw cents to dollars and cents portion,
// automatically adjusting the cents portion so that it is always positive,
// for easier display.
static void
decode_usd(int16_t amount_cents, bool* out_is_negative, int16_t* out_usd, uint16_t* out_cents) {
*out_usd = amount_cents / 100;
if(amount_cents >= 0) {
*out_is_negative = false;
*out_cents = amount_cents % 100;
} else {
*out_is_negative = true;
*out_cents = (amount_cents * -1) % 100;
}
}
// Decode a raw 1900-based timestamp and append a human-readable form to a
// FuriString.
static void furi_string_cat_timestamp(
FuriString* str,
const char* date_hdr,
const char* time_hdr,
uint32_t tmst_1900) {
FuriHalRtcDateTime tm;
epoch_1900_datetime_to_furi(tmst_1900, &tm);
FuriString* date_str = furi_string_alloc();
locale_format_date(date_str, &tm, locale_get_date_format(), "-");
FuriString* time_str = furi_string_alloc();
locale_format_time(time_str, &tm, locale_get_time_format(), true);
furi_string_cat_printf(
str,
"%s%s%s%s (UTC)",
date_hdr,
furi_string_get_cstr(date_str),
time_hdr,
furi_string_get_cstr(time_str));
furi_string_free(date_str);
furi_string_free(time_str);
}
// Convert a "1900"-based timestamp to Furi time, assuming a UTC/GMT timezone.
static void epoch_1900_datetime_to_furi(uint32_t seconds, FuriHalRtcDateTime* out) {
uint16_t year, month, day, hour, minute, second;
// Calculate absolute number of days elapsed since the 1900 epoch
// and save the residual for the time within the day.
uint32_t absolute_days = seconds / 86400;
uint32_t seconds_within_day = seconds % 86400;
// Calculate day of the week.
// January 1, 1900 was a Monday ("day of week" = 1)
uint8_t dow = (absolute_days + 1) % 7;
//
// Compute the date by simply marching through time in as large chunks
// as possible.
//
for(year = 1900;; year++) {
uint16_t year_days = furi_hal_rtc_get_days_per_year(year);
if(absolute_days >= year_days)
absolute_days -= year_days;
else
break;
}
bool is_leap = furi_hal_rtc_is_leap_year(year);
for(month = 1;; month++) {
uint8_t days_in_month = furi_hal_rtc_get_days_per_month(is_leap, month);
if(absolute_days >= days_in_month)
absolute_days -= days_in_month;
else
break;
}
day = absolute_days + 1;
hour = seconds_within_day / 3600;
uint16_t sub_hour = seconds_within_day % 3600;
minute = sub_hour / 60;
second = sub_hour % 60;
out->year = year;
out->month = month;
out->day = day;
out->hour = hour;
out->minute = minute;
out->second = second;
out->weekday = dow;
}
/* Actual implementation of app<>plugin interface */
static const NfcSupportedCardsPlugin clipper_plugin = {
.protocol = NfcProtocolMfDesfire,
.verify = NULL,
.read = NULL,
.parse = clipper_parse,
};
/* Plugin descriptor to comply with basic plugin specification */
static const FlipperAppPluginDescriptor clipper_plugin_descriptor = {
.appid = NFC_SUPPORTED_CARD_PLUGIN_APP_ID,
.ep_api_version = NFC_SUPPORTED_CARD_PLUGIN_API_VERSION,
.entry_point = &clipper_plugin,
};
/* Plugin entry point - must return a pointer to const descriptor */
const FlipperAppPluginDescriptor* clipper_plugin_ep() {
return &clipper_plugin_descriptor;
}