vw-nm.c

   1 /*
   2  * Copyright 2015-2016 Max Staudt
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License 2 as published
   6  * by the Free Software Foundation.
   7  */
   8
   9 #include <assert.h>
  10
  11 #include <stdio.h>
  12 #include <stdint.h>
  13 #include <unistd.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <sys/types.h>
  17 #include <sys/socket.h>
  18 #include <linux/can.h>
  19 #include <linux/can/raw.h>
  20 #include <net/if.h>
  21 #include <sys/ioctl.h>
  22 #include <endian.h>
  23 #include <sys/time.h>
  24
  25
  26 #include "vw-nm.h"
  27 #include "vw-nm-tools.h"
  28
  29
  30
  31 static int nm_is_rx_frame_valid(struct NM_Main *nm, struct can_frame *frame)
  32 {
  33         if (frame->can_dlc < 2) {
  34                 printf("Skipping short frame from CAN ID %03x\n", frame->can_id);
  35                 return 0;
  36         }
  37
  38         if ((frame->can_id & ~(nm->max_nodes - 1)) != nm->can_base) {
  39                 printf("Skipping non-NM from CAN ID %03x\n", frame->can_id);
  40                 return 0;
  41         }
  42
  43         return 1;
  44 }
  45
  46
  47
  48
  49 static void nm_update_my_next_id(struct NM_Main *nm) {
  50         unsigned id = nm->my_id;
  51
  52         do {
  53                 NM_State state;
  54
  55                 id++;
  56                 if (id >= nm->max_nodes) {
  57                         id = 0;
  58                 }
  59
  60                 state = nm->nodes[id].state & NM_MAIN_MASK;
  61
  62                 if (state == NM_MAIN_ON || state == NM_MAIN_LOGIN) {
  63                         /* We skip limp home nodes */
  64                         nm->nodes[nm->my_id].next = id;
  65                         break;
  66                 }
  67         } while (id != nm->my_id);
  68 }
  69
  70
  71
  72 static void nm_handle_can_frame(struct NM_Main *nm, struct can_frame *frame)
  73 {
  74         NM_ID sender, next;
  75         NM_State state;
  76
  77         /* Is this a valid frame within our logical network? */
  78         if (!nm_is_rx_frame_valid(nm, frame)) {
  79                 return;
  80         }
  81
  82         printf("Received NM frame from CAN ID %03x\n", frame->can_id);
  83
  84
  85         /* Parse sender, its perceived successor, and its state */
  86         sender = frame->can_id & (nm->max_nodes - 1);
  87         next = frame->data[0];
  88         state = frame->data[1];
  89
  90         /* TODO: Validate state, it needs to be within the enum */
  91
  92         /* Skip our own frames */
  93         if (sender == nm->my_id) {
  94                 return;
  95         }
  96
  97         nm->nodes[sender].next = next;
  98         nm->nodes[sender].state = state;
  99
 100         switch (state & NM_MAIN_MASK) {
 101                 case NM_MAIN_ON:
 102                         if (next == nm->nodes[nm->my_id].next
 103                                 && nm->nodes[nm->my_id].next != nm->my_id) {
 104                                 /* sender doesn't know we exist */
 105
 106                                 nm->nodes[nm->my_id].state = NM_MAIN_LOGIN;
 107
 108                                 nm->tv.tv_sec = 0;
 109                                 nm->tv.tv_usec = 0;
 110                                 /* IMPORTANT: The caller needs to check for
 111                                  * timeouts first, i.e. no other NM frames
 112                                  * are received until our correcting login
 113                                  * has been sent.
 114                                  */
 115                         } else if (next == nm->nodes[nm->my_id].next) {
 116                                 /* where (nm->nodes[nm->my_id].next == nm->my_id) */
 117
 118                                 /* It can happen when:
 119                                  *  - our sent frames don't go anywhere
 120                                  *  - we just logged in and immediately
 121                                  *    afterwards another ECU sent a regular
 122                                  *    NM frame.
 123                                  */
 124
 125                                 /* Let's handle this just like a LOGIN, since
 126                                  * we're learning about a new device.
 127                                  * See case NM_MAIN_LOGIN below for details.
 128                                  */
 129
 130                                 nm_update_my_next_id(nm);
 131                                 nm->nodes[nm->my_id].state = NM_MAIN_ON;
 132                         } else if (next == nm->my_id) {
 133                                 /* It's our turn.
 134                                  * Reset the timeout so anyone we missed
 135                                  * can send its login frame to correct us.
 136                                  */
 137                                 nm->tv.tv_sec = 0;
 138                                 nm->tv.tv_usec = NM_USECS_MY_TURN;
 139                         } else {
 140                                 /* We just got some random ON message.
 141                                  * Reset the timer looking out for broken
 142                                  * connectivity.
 143                                  */
 144                                 nm->tv.tv_sec = 0;
 145                                 nm->tv.tv_usec = NM_USECS_OTHER_TURN;
 146                         }
 147                         break;
 148                 case NM_MAIN_LOGIN:
 149                         /* Note: sender != nm->my_id */
 150
 151                         nm_update_my_next_id(nm);
 152
 153                         /* We're not alone anymore, so let's change state. */
 154                         nm->nodes[nm->my_id].state = NM_MAIN_ON;
 155
 156                         /* We don't reset the timeout when somebody logs in,
 157                          * i.e. (next == sender).
 158                          * Instead, we'll simply include them in the next
 159                          * round. */
 160
 161                         /* Actually, when a login is done as a correction,
 162                          * we do reset the timeout.
 163                          */
 164                         if (next != sender) {
 165                                 nm->tv.tv_sec = 0;
 166                                 nm->tv.tv_usec = NM_USECS_OTHER_TURN;
 167                         }
 168                         break;
 169         }
 170
 171         nm_dump_all(nm);
 172 }
 173
 174
 175
 176
 177
 178
 179 static void nm_buildframe(struct NM_Main *nm, struct can_frame *frame)
 180 {
 181         frame->can_id = nm->can_base + nm->my_id;
 182         frame->can_dlc = 2;
 183         frame->data[0] = nm->nodes[nm->my_id].next;
 184         frame->data[1] = nm->nodes[nm->my_id].state;
 185 }
 186
 187
 188
 189
 190 static void nm_timeout_callback(struct NM_Main *nm, struct can_frame *frame)
 191 {
 192         nm->tv.tv_sec = 0;
 193         nm->tv.tv_usec = NM_USECS_OTHER_TURN;
 194
 195         nm_buildframe(nm, frame);
 196 }
 197
 198
 199
 200
 201 static void nm_start(struct NM_Main *nm, struct can_frame *frame)
 202 {
 203         nm->tv.tv_sec = 0;
 204         nm->tv.tv_usec = 50000;
 205
 206
 207
 208         nm->nodes[nm->my_id].next = nm->my_id;
 209         nm->nodes[nm->my_id].state = NM_MAIN_LOGIN;
 210
 211         nm_buildframe(nm, frame);
 212 }
 213
 214
 215
 216
 217 static int net_init(char *ifname)
 218 {
 219         int s;
 220         int recv_own_msgs;
 221         struct sockaddr_can addr;
 222         struct ifreq ifr;
 223         struct can_filter fi;
 224
 225         s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 226         if (s < 0) {
 227                 perror("socket");
 228                 exit(1);
 229         }
 230
 231         /* Convert interface name to index */
 232         memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
 233         strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
 234         if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
 235                 perror("SIOCGIFINDEX");
 236                 exit(1);
 237         }
 238
 239         /* Open the CAN interface */
 240         memset(&addr, 0, sizeof(addr));
 241         addr.can_family = AF_CAN;
 242         addr.can_ifindex = ifr.ifr_ifindex;
 243         if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
 244                 perror("bind");
 245                 return 0;
 246         }
 247
 248         recv_own_msgs = 1; /* 0 = disabled (default), 1 = enabled */
 249         setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
 250                         &recv_own_msgs, sizeof(recv_own_msgs));
 251
 252         /* Handle only 32 NM IDs at CAN base ID 0x420 */
 253         fi.can_id   = 0x420;
 254         fi.can_mask = 0x7E0;
 255
 256         setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &fi, sizeof(struct can_filter));
 257
 258         return s;
 259 }
 260
 261
 262 int main(int argc, char **argv)
 263 {
 264         struct NM_Main *nm;
 265         fd_set rdfs;
 266         int s;
 267
 268         if (argc != 2) {
 269                 printf("syntax: %s IFNAME\n", argv[0]);
 270                 return 1;
 271         }
 272
 273         nm = nm_alloc(5, 0x0b, 0x420);
 274         if (!nm) {
 275                 printf("Out of memory allocating NM struct.\n");
 276                 return 1;
 277         }
 278
 279         s = net_init(argv[1]);
 280
 281         /* Stir up the hornet's nest */
 282         if (1) {
 283                 struct can_frame frame;
 284
 285                 nm_start(nm, &frame);
 286                 can_tx(s, &frame);
 287         }
 288
 289         while (1) {
 290                 int retval;
 291
 292                 FD_ZERO(&rdfs);
 293                 FD_SET(s, &rdfs);
 294
 295                 retval = select(s+1, &rdfs, NULL, NULL, &nm->tv);
 296                 /* We currently rely on Linux timeout behavior here,
 297                  * i.e. the timeout now reflects the remaining time */
 298                 if (retval < 0) {
 299                         perror("select");
 300                         return 1;
 301                 } else if (!retval) {
 302                         /* Timeout, we NEED to check this first */
 303                         struct can_frame frame;
 304
 305                         nm_timeout_callback(nm, &frame);
 306                         can_tx(s, &frame);
 307                 } else if (FD_ISSET(s, &rdfs)) {
 308                         struct can_frame frame;
 309                         ssize_t ret;
 310
 311                         ret = read(s, &frame, sizeof(frame));
 312                         if (ret < 0) {
 313                                 perror("recvfrom CAN socket");
 314                                 return 1;
 315                         }
 316
 317                         nm_handle_can_frame(nm, &frame);
 318                         continue;
 319                 }
 320         }
 321
 322         nm_free(nm);
 323
 324         return 0;
 325 }