src/obd2/obd2.c

   1 #include <obd2/obd2.h>
   2 #include <arpa/inet.h>
   3
   4 #define ARBITRATION_ID_OFFSET 0x8
   5 #define MODE_RESPONSE_OFFSET 0x40
   6 #define NEGATIVE_RESPONSE_MODE 0x7f
   7 #define MAX_DIAGNOSTIC_PAYLOAD_SIZE 6
   8 #define MODE_BYTE_INDEX 0
   9 #define PID_BYTE_INDEX 1
  10 #define NEGATIVE_RESPONSE_MODE_INDEX 1
  11 #define NEGATIVE_RESPONSE_NRC_INDEX 2
  12
  13 DiagnosticShims diagnostic_init_shims(LogShim log,
  14         SendCanMessageShim send_can_message,
  15         SetTimerShim set_timer) {
  16     DiagnosticShims shims = {
  17         log: log,
  18         send_can_message: send_can_message,
  19         set_timer: set_timer
  20     };
  21     return shims;
  22 }
  23
  24 DiagnosticRequestHandle diagnostic_request(DiagnosticShims* shims,
  25         DiagnosticRequest* request, DiagnosticResponseReceived callback) {
  26     DiagnosticRequestHandle handle = {
  27         request: *request,
  28         callback: callback,
  29         success: false,
  30         completed: false
  31     };
  32
  33     uint8_t payload[MAX_DIAGNOSTIC_PAYLOAD_SIZE];
  34     payload[MODE_BYTE_INDEX] = request->mode;
  35     if(request->pid_length > 0) {
  36         copy_bytes_right_aligned(&request->pid, sizeof(request->pid),
  37                 PID_BYTE_INDEX, request->pid_length, payload, sizeof(payload));
  38     }
  39     if(request->payload_length > 0) {
  40         memcpy(&payload[PID_BYTE_INDEX + request->pid_length],
  41                 request->payload, request->payload_length);
  42     }
  43
  44     handle.isotp_shims = isotp_init_shims(shims->log,
  45             shims->send_can_message,
  46             shims->set_timer);
  47     handle.isotp_send_handle = isotp_send(&handle.isotp_shims,
  48             request->arbitration_id, payload,
  49             1 + request->payload_length + request->pid_length,
  50             NULL);
  51
  52     handle.isotp_receive_handle = isotp_receive(&handle.isotp_shims,
  53             request->arbitration_id + ARBITRATION_ID_OFFSET,
  54             NULL);
  55
  56     // TODO notes on multi frame:
  57     // TODO what are the timers for exactly?
  58     //
  59     // when sending multi frame, send 1 frame, wait for a response
  60     // if it says send all, send all right away
  61     // if it says flow control, set the time for the next send
  62     // instead of creating a timer with an async callback, add a process_handle
  63     // function that's called repeatedly in the main loop - if it's time to
  64     // send, we do it. so there's a process_handle_send and receive_can_frame
  65     // that are just called continuously from the main loop. it's a waste of a
  66     // few cpu cycles but it may be more  natural than callbacks.
  67     //
  68     // what woudl a timer callback look like...it would need to pass the handle
  69     // and that's all. seems like a context void* would be able to capture all
  70     // of the information but arg, memory allocation. look at how it's done in
  71     // the other library again
  72     //
  73     return handle;
  74 }
  75
  76 DiagnosticRequestHandle diagnostic_request_pid(DiagnosticShims* shims,
  77         DiagnosticPidRequestType pid_request_type, uint16_t arbitration_id,
  78         uint16_t pid, DiagnosticResponseReceived callback) {
  79     DiagnosticRequest request = {
  80         arbitration_id: arbitration_id,
  81         mode: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 0x1 : 0x22,
  82         pid: pid,
  83         pid_length: pid_request_type == DIAGNOSTIC_STANDARD_PID ? 1 : 2
  84     };
  85
  86     return diagnostic_request(shims, &request, callback);
  87 }
  88
  89 static bool handle_negative_response(IsoTpMessage* message,
  90         DiagnosticResponse* response, DiagnosticShims* shims) {
  91     bool response_was_negative = false;
  92     if(response->mode == NEGATIVE_RESPONSE_MODE) {
  93         response_was_negative = true;
  94         if(message->size > NEGATIVE_RESPONSE_MODE_INDEX) {
  95             response->mode = message->payload[NEGATIVE_RESPONSE_MODE_INDEX];
  96         }
  97
  98         if(message->size > NEGATIVE_RESPONSE_NRC_INDEX) {
  99             response->negative_response_code = message->payload[NEGATIVE_RESPONSE_NRC_INDEX];
 100         }
 101
 102         response->success = false;
 103         response->completed = true;
 104     }
 105     return response_was_negative;
 106 }
 107
 108 static bool handle_positive_response(DiagnosticRequestHandle* handle,
 109         IsoTpMessage* message, DiagnosticResponse* response,
 110         DiagnosticShims* shims) {
 111     bool response_was_positive = false;
 112     if(response->mode == handle->request.mode + MODE_RESPONSE_OFFSET) {
 113         response_was_positive = true;
 114         // hide the "response" version of the mode from the user
 115         // if it matched
 116         response->mode = handle->request.mode;
 117         if(handle->request.pid_length > 0 && message->size > 1) {
 118             if(handle->request.pid_length == 2) {
 119                 response->pid = *(uint16_t*)&message->payload[PID_BYTE_INDEX];
 120                 response->pid = ntohs(response->pid);
 121             } else {
 122                 response->pid = message->payload[PID_BYTE_INDEX];
 123             }
 124         }
 125
 126         uint8_t payload_index = 1 + handle->request.pid_length;
 127         response->payload_length = message->size - payload_index;
 128         if(response->payload_length > 0) {
 129             memcpy(response->payload, &message->payload[payload_index],
 130                     response->payload_length);
 131         }
 132         response->success = true;
 133         response->completed = true;
 134     }
 135     return response_was_positive;
 136 }
 137
 138 DiagnosticResponse diagnostic_receive_can_frame(DiagnosticShims* shims,
 139         DiagnosticRequestHandle* handle, const uint16_t arbitration_id,
 140         const uint8_t data[], const uint8_t size) {
 141
 142     DiagnosticResponse response = {
 143         arbitration_id: arbitration_id,
 144         success: false,
 145         completed: false
 146     };
 147
 148     if(!handle->isotp_send_handle.completed) {
 149         isotp_continue_send(&handle->isotp_shims,
 150                 &handle->isotp_send_handle, arbitration_id, data, size);
 151     } else if(!handle->isotp_receive_handle.completed) {
 152         IsoTpMessage message = isotp_continue_receive(&handle->isotp_shims,
 153                 &handle->isotp_receive_handle, arbitration_id, data, size);
 154
 155         if(message.completed) {
 156             if(message.size > 0) {
 157                 response.mode = message.payload[0];
 158                 if(handle_negative_response(&message, &response, shims)) {
 159                     shims->log("Received a negative response to mode %d on arb ID 0x%x",
 160                             response.mode, response.arbitration_id);
 161
 162                     // TODO clarify what it means for a handle to be successful (we made
 163                     // a good request+response) vs a request itself being
 164                     // successfully
 165                     // (the other node didn't return a negative response).
 166                     handle->success = true;
 167                     handle->completed = true;
 168                 } else if(handle_positive_response(handle, &message, &response,
 169                             shims)) {
 170                     shims->log("Received a positive mode %d response on arb ID 0x%x",
 171                             response.mode, response.arbitration_id);
 172                     handle->success = true;
 173                     handle->completed = true;
 174                 } else {
 175                     shims->log("Response was for a mode 0x%x request, not our mode 0x%x request",
 176                             response.mode - MODE_RESPONSE_OFFSET,
 177                             handle->request.mode);
 178                 }
 179             }
 180
 181             if(handle->completed && handle->callback != NULL) {
 182                 handle->callback(&response);
 183             }
 184         }
 185
 186     } else {
 187         shims->log("Mode %d request to arb ID 0x%x is already completed",
 188                 handle->request.mode, handle->request.arbitration_id);
 189     }
 190     return response;
 191 }