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         /* If we're currently stuck in Limp Home mode, and we can see
  82          * someone else's messages, reset and re-login.
  83          */
  84         if (nm->nodes[nm->my_id].state == NM_MAIN_LIMPHOME) {
  85                 nm_reset(nm);
  86                 return;
  87         }
  88
  89         nm->nodes[sender].next = next;
  90         nm->nodes[sender].state = state;
  91
  92         /* Update our view of the world */
  93         nm_update_my_next_id(nm);
  94
  95         switch (state & NM_MAIN_MASK) {
  96                 case NM_MAIN_ON:
  97                         /* We're not alone, so let's transition to ON for now.
  98                          */
  99                         nm->nodes[nm->my_id].state = NM_MAIN_ON;
 100
 101                         /* The AWOL timeout is ONLY reset on
 102                          * NM_MAIN_ON messages.
 103                          */
 104                         nm_set_timer_awol(nm);
 105
 106                         if (next == nm->nodes[nm->my_id].next
 107                                 && nm->nodes[nm->my_id].next != nm->my_id) {
 108                                 /* Sender doesn't know we exist */
 109
 110                                 nm->nodes[nm->my_id].state = NM_MAIN_LOGIN;
 111
 112                                 nm_set_timer_now(nm);
 113
 114                                 /* IMPORTANT: The caller needs to check for
 115                                  * timeouts first, i.e. no other NM frames
 116                                  * are received until our correcting login
 117                                  * has been sent.
 118                                  */
 119                         } else if (next == nm->nodes[nm->my_id].next) {
 120                                 /* where (nm->nodes[nm->my_id].next == nm->my_id) */
 121
 122                                 /* It can happen when:
 123                                  *  - our sent frames don't go anywhere
 124                                  *  - we just logged in and immediately
 125                                  *    afterwards another ECU sent a regular
 126                                  *    NM frame.
 127                                  */
 128
 129                                 /* Nothing to do. */
 130                         } else if (next == nm->my_id) {
 131                                 /* It's our turn, do a normal timeout.
 132                                  * This is a period in which anyone we missed
 133                                  * can send its re-login frame to correct us.
 134                                  */
 135
 136                                 nm_set_timer_normal(nm);
 137                         } else {
 138                                 /* We just received a random ON message. */
 139
 140                                 /* Nothing to do. */
 141                         }
 142                         break;
 143                 case NM_MAIN_LOGIN:
 144                         /* Note: sender != nm->my_id */
 145
 146                         /* We're not alone anymore, so let's change state. */
 147                         nm->nodes[nm->my_id].state = NM_MAIN_ON;
 148
 149                         /* We don't reset the timeout when somebody logs in.
 150                          * Instead, we'll simply include them in the next
 151                          * round.
 152                          */
 153
 154                         /* Nothing else to do. */
 155                         break;
 156                 case NM_MAIN_LIMPHOME:
 157                         /* Nothing we can do. Poor guy. */
 158                         break;
 159         }
 160
 161         nm_dump_all(nm);
 162 }
 163
 164
 165
 166
 167
 168
 169 static void nm_buildframe(struct NM_Main *nm, struct can_frame *frame)
 170 {
 171         frame->can_id = nm->can_base + nm->my_id;
 172         frame->can_dlc = 2;
 173         frame->data[0] = nm->nodes[nm->my_id].next;
 174         frame->data[1] = nm->nodes[nm->my_id].state;
 175 }
 176
 177
 178
 179
 180 static void nm_timeout_callback(struct NM_Main *nm, struct can_frame *frame)
 181 {
 182         nm_buildframe(nm, frame);
 183
 184         switch(nm->timer_reason) {
 185                 case NM_TIMER_NOW:
 186                         /* We're due to log in */
 187
 188                         /* We're going to be ready, let's
 189                          * change state (RCD 310 behavior)
 190                          */
 191                         nm->nodes[nm->my_id].state = NM_MAIN_ON;
 192                         nm_set_timer_normal(nm);
 193                         break;
 194                 case NM_TIMER_NORMAL:
 195                         /* We're due to send our own ring message */
 196                         switch(nm->nodes[nm->my_id].state & NM_MAIN_MASK) {
 197                                 case NM_MAIN_ON:
 198                                         break;
 199                                 default:
 200                                         printf("BUG: TIMER_NORMAL expired in non-ON state\n");
 201                                         break;
 202                         }
 203                         nm_set_timer_awol(nm);
 204                         break;
 205                 case NM_TIMER_AWOL:
 206                         /* The network is silent because a node disappeared
 207                          * or something bad happened.
 208                          * Reset everything and start over.
 209                          */
 210                         nm_reset(nm);
 211                         break;
 212                 case NM_TIMER_LIMPHOME:
 213                         nm_set_timer_limphome(nm);
 214                         break;
 215         }
 216 }
 217
 218
 219
 220
 221 static int net_init(char *ifname)
 222 {
 223         int s;
 224         int recv_own_msgs;
 225         struct sockaddr_can addr;
 226         struct ifreq ifr;
 227         struct can_filter fi;
 228
 229         s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 230         if (s < 0) {
 231                 perror("socket");
 232                 exit(1);
 233         }
 234
 235         /* Convert interface name to index */
 236         memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
 237         strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
 238         if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
 239                 perror("SIOCGIFINDEX");
 240                 exit(1);
 241         }
 242
 243         /* Open the CAN interface */
 244         memset(&addr, 0, sizeof(addr));
 245         addr.can_family = AF_CAN;
 246         addr.can_ifindex = ifr.ifr_ifindex;
 247         if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
 248                 perror("bind");
 249                 return 0;
 250         }
 251
 252         recv_own_msgs = 1; /* 0 = disabled (default), 1 = enabled */
 253         setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
 254                         &recv_own_msgs, sizeof(recv_own_msgs));
 255
 256         /* Handle only 32 NM IDs at CAN base ID 0x420 */
 257         fi.can_id   = 0x420;
 258         fi.can_mask = 0x7E0;
 259
 260         setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &fi, sizeof(struct can_filter));
 261
 262         return s;
 263 }
 264
 265
 266 int main(int argc, char **argv)
 267 {
 268         struct NM_Main *nm;
 269         fd_set rdfs;
 270         int s;
 271         NM_ID my_id;
 272
 273         if (argc != 3) {
 274                 printf("syntax: %s IFNAME MY_ID\n", argv[0]);
 275                 return 1;
 276         }
 277
 278         my_id = strtoul(argv[2], NULL, 0);
 279
 280         nm = nm_alloc(5, my_id, 0x420);
 281         if (!nm) {
 282                 printf("Out of memory allocating NM struct.\n");
 283                 return 1;
 284         }
 285
 286         s = net_init(argv[1]);
 287
 288         while (1) {
 289                 int retval;
 290
 291                 FD_ZERO(&rdfs);
 292                 FD_SET(s, &rdfs);
 293
 294                 retval = select(s+1, &rdfs, NULL, NULL, &nm->tv);
 295                 /* We currently rely on Linux timeout behavior here,
 296                  * i.e. the timeout now reflects the remaining time */
 297                 if (retval < 0) {
 298                         perror("select");
 299                         return 1;
 300                 } else if (!retval) {
 301                         /* Timeout, we NEED to check this first */
 302                         struct can_frame frame;
 303
 304                         nm_timeout_callback(nm, &frame);
 305                         can_tx(s, &frame);
 306                 } else if (FD_ISSET(s, &rdfs)) {
 307                         struct can_frame frame;
 308                         ssize_t ret;
 309
 310                         ret = read(s, &frame, sizeof(frame));
 311                         if (ret < 0) {
 312                                 perror("recvfrom CAN socket");
 313                                 return 1;
 314                         }
 315
 316                         nm_handle_can_frame(nm, &frame);
 317                         continue;
 318                 }
 319         }
 320
 321         nm_free(nm);
 322         close(s);
 323
 324         return 0;
 325 }