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
  32
  33 static void nm_update_my_next_id(struct NM_Main *nm) {
  34         unsigned id = nm->my_id;
  35
  36         do {
  37                 NM_State state;
  38
  39                 id++;
  40                 if (id >= nm->max_nodes) {
  41                         id = 0;
  42                 }
  43
  44                 state = nm->nodes[id].state & NM_MAIN_MASK;
  45
  46                 if (state == NM_MAIN_ON || state == NM_MAIN_LOGIN) {
  47                         /* We skip limp home nodes */
  48                         nm->nodes[nm->my_id].next = id;
  49                         break;
  50                 }
  51         } while (id != nm->my_id);
  52 }
  53
  54
  55
  56 static void nm_handle_can_frame(struct NM_Main *nm, struct can_frame *frame)
  57 {
  58         NM_ID sender, next;
  59         NM_State state;
  60
  61         /* Is this a valid frame within our logical network? */
  62         if (!nm_is_rx_frame_valid(nm, frame)) {
  63                 return;
  64         }
  65
  66         printf("Received NM frame from CAN ID %03x\n", frame->can_id);
  67
  68
  69         /* Parse sender, its perceived successor, and its state */
  70         sender = frame->can_id & (nm->max_nodes - 1);
  71         next = frame->data[0];
  72         state = frame->data[1];
  73
  74         /* TODO: Validate state, it needs to be within the enum */
  75
  76         /* Skip our own frames */
  77         if (sender == nm->my_id) {
  78                 return;
  79         }
  80
  81         nm->nodes[sender].next = next;
  82         nm->nodes[sender].state = state;
  83
  84         /* Update our view of the world */
  85         nm_update_my_next_id(nm);
  86
  87         switch (state & NM_MAIN_MASK) {
  88                 case NM_MAIN_ON:
  89                         /* We're not alone, so let's transition to ON for now.
  90                          */
  91                         nm->nodes[nm->my_id].state = NM_MAIN_ON;
  92
  93                         /* The AWOL timeout is ONLY reset on
  94                          * NM_MAIN_ON messages.
  95                          */
  96                         nm_set_timer_awol(nm);
  97
  98                         if (next == nm->nodes[nm->my_id].next
  99                                 && nm->nodes[nm->my_id].next != nm->my_id) {
 100                                 /* Sender doesn't know we exist */
 101
 102                                 nm->nodes[nm->my_id].state = NM_MAIN_LOGIN;
 103
 104                                 nm_set_timer_now(nm);
 105
 106                                 /* IMPORTANT: The caller needs to check for
 107                                  * timeouts first, i.e. no other NM frames
 108                                  * are received until our correcting login
 109                                  * has been sent.
 110                                  */
 111                         } else if (next == nm->nodes[nm->my_id].next) {
 112                                 /* where (nm->nodes[nm->my_id].next == nm->my_id) */
 113
 114                                 /* It can happen when:
 115                                  *  - our sent frames don't go anywhere
 116                                  *  - we just logged in and immediately
 117                                  *    afterwards another ECU sent a regular
 118                                  *    NM frame.
 119                                  */
 120
 121                                 /* Nothing to do. */
 122                         } else if (next == nm->my_id) {
 123                                 /* It's our turn, do a normal timeout.
 124                                  * This is a period in which anyone we missed
 125                                  * can send its re-login frame to correct us.
 126                                  */
 127
 128                                 nm_set_timer_normal(nm);
 129                         } else {
 130                                 /* We just received a random ON message. */
 131
 132                                 /* Nothing to do. */
 133                         }
 134                         break;
 135                 case NM_MAIN_LOGIN:
 136                         /* Note: sender != nm->my_id */
 137
 138                         /* We're not alone anymore, so let's change state. */
 139                         nm->nodes[nm->my_id].state = NM_MAIN_ON;
 140
 141                         /* We don't reset the timeout when somebody logs in.
 142                          * Instead, we'll simply include them in the next
 143                          * round.
 144                          */
 145
 146                         /* Nothing else to do. */
 147                         break;
 148                 case NM_MAIN_LIMPHOME:
 149                         break;
 150         }
 151
 152         nm_dump_all(nm);
 153 }
 154
 155
 156
 157
 158
 159
 160 static void nm_buildframe(struct NM_Main *nm, struct can_frame *frame)
 161 {
 162         frame->can_id = nm->can_base + nm->my_id;
 163         frame->can_dlc = 2;
 164         frame->data[0] = nm->nodes[nm->my_id].next;
 165         frame->data[1] = nm->nodes[nm->my_id].state;
 166 }
 167
 168
 169
 170
 171 static void nm_timeout_callback(struct NM_Main *nm, struct can_frame *frame)
 172 {
 173         switch(nm->timer_reason) {
 174                 case NM_TIMER_NOW:
 175                 case NM_TIMER_NORMAL:
 176                         /* We're due to send our own ring message */
 177                         switch(nm->nodes[nm->my_id].state & NM_MAIN_MASK) {
 178                                 case NM_MAIN_ON:
 179                                         break;
 180                                 case NM_MAIN_LOGIN:
 181                                         /* We're going to be ready, let's
 182                                          * change state (RCD 310 behavior)
 183                                          */
 184                                         nm->nodes[nm->my_id].state = NM_MAIN_ON;
 185                                         break;
 186                                 default:
 187                                         printf("BUG: TIMER_NORMAL expired in unknown NM_MAIN state\n");
 188                                         break;
 189                         }
 190                         nm_set_timer_awol(nm);
 191                         nm_buildframe(nm, frame);
 192                         break;
 193                 case NM_TIMER_AWOL:
 194                         /* The network is silent because a node disappeared
 195                          * or something bad happened.
 196                          * Reset everything and start over.
 197                          */
 198                         nm_reset(nm);
 199                         break;
 200                 case NM_TIMER_LIMPHOME:
 201                         /* TODO */
 202                         break;
 203         }
 204
 205         nm_buildframe(nm, frame);
 206 }
 207
 208
 209
 210
 211 static int net_init(char *ifname)
 212 {
 213         int s;
 214         int recv_own_msgs;
 215         struct sockaddr_can addr;
 216         struct ifreq ifr;
 217         struct can_filter fi;
 218
 219         s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 220         if (s < 0) {
 221                 perror("socket");
 222                 exit(1);
 223         }
 224
 225         /* Convert interface name to index */
 226         memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
 227         strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
 228         if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
 229                 perror("SIOCGIFINDEX");
 230                 exit(1);
 231         }
 232
 233         /* Open the CAN interface */
 234         memset(&addr, 0, sizeof(addr));
 235         addr.can_family = AF_CAN;
 236         addr.can_ifindex = ifr.ifr_ifindex;
 237         if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
 238                 perror("bind");
 239                 return 0;
 240         }
 241
 242         recv_own_msgs = 1; /* 0 = disabled (default), 1 = enabled */
 243         setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
 244                         &recv_own_msgs, sizeof(recv_own_msgs));
 245
 246         /* Handle only 32 NM IDs at CAN base ID 0x420 */
 247         fi.can_id   = 0x420;
 248         fi.can_mask = 0x7E0;
 249
 250         setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &fi, sizeof(struct can_filter));
 251
 252         return s;
 253 }
 254
 255
 256 int main(int argc, char **argv)
 257 {
 258         struct NM_Main *nm;
 259         fd_set rdfs;
 260         int s;
 261         NM_ID my_id;
 262
 263         if (argc != 3) {
 264                 printf("syntax: %s IFNAME MY_ID\n", argv[0]);
 265                 return 1;
 266         }
 267
 268         my_id = strtoul(argv[2], NULL, 0);
 269
 270         nm = nm_alloc(5, my_id, 0x420);
 271         if (!nm) {
 272                 printf("Out of memory allocating NM struct.\n");
 273                 return 1;
 274         }
 275
 276         s = net_init(argv[1]);
 277
 278         /* Stir up the hornet's nest */
 279         if (1) {
 280                 struct can_frame frame;
 281
 282                 nm_buildframe(nm, &frame);
 283                 can_tx(s, &frame);
 284         }
 285
 286         while (1) {
 287                 int retval;
 288
 289                 FD_ZERO(&rdfs);
 290                 FD_SET(s, &rdfs);
 291
 292                 retval = select(s+1, &rdfs, NULL, NULL, &nm->tv);
 293                 /* We currently rely on Linux timeout behavior here,
 294                  * i.e. the timeout now reflects the remaining time */
 295                 if (retval < 0) {
 296                         perror("select");
 297                         return 1;
 298                 } else if (!retval) {
 299                         /* Timeout, we NEED to check this first */
 300                         struct can_frame frame;
 301
 302                         nm_timeout_callback(nm, &frame);
 303                         can_tx(s, &frame);
 304                 } else if (FD_ISSET(s, &rdfs)) {
 305                         struct can_frame frame;
 306                         ssize_t ret;
 307
 308                         ret = read(s, &frame, sizeof(frame));
 309                         if (ret < 0) {
 310                                 perror("recvfrom CAN socket");
 311                                 return 1;
 312                         }
 313
 314                         nm_handle_can_frame(nm, &frame);
 315                         continue;
 316                 }
 317         }
 318
 319         nm_free(nm);
 320         close(s);
 321
 322         return 0;
 323 }