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                         /* TODO: Check for 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, so no other NM frames are
 112                                  * received until our correcting login has
 113                                  * 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                          * Instead, we'll simply include them in the next
 158                          * round. */
 159
 160                         /* Actually, when a login is done as a correction,
 161                          * we do reset the timeout.
 162                          *
 163                          * TODO.
 164                          */
 165                         break;
 166         }
 167
 168         nm_dump_all(nm);
 169 }
 170
 171
 172
 173
 174
 175
 176 static void nm_buildframe(struct NM_Main *nm, struct can_frame *frame)
 177 {
 178         frame->can_id = nm->can_base + nm->my_id;
 179         frame->can_dlc = 2;
 180         frame->data[0] = nm->nodes[nm->my_id].next;
 181         frame->data[1] = nm->nodes[nm->my_id].state;
 182 }
 183
 184
 185
 186
 187 static void nm_timeout_callback(struct NM_Main *nm, struct can_frame *frame)
 188 {
 189         nm->tv.tv_sec = 0;
 190         nm->tv.tv_usec = NM_USECS_OTHER_TURN;
 191
 192         nm_buildframe(nm, frame);
 193 }
 194
 195
 196
 197
 198 static void nm_start(struct NM_Main *nm, struct can_frame *frame)
 199 {
 200         nm->tv.tv_sec = 0;
 201         nm->tv.tv_usec = 50000;
 202
 203
 204
 205         nm->nodes[nm->my_id].next = nm->my_id;
 206         nm->nodes[nm->my_id].state = NM_MAIN_LOGIN;
 207
 208         nm_buildframe(nm, frame);
 209 }
 210
 211
 212
 213
 214 static int net_init(char *ifname)
 215 {
 216         int s;
 217         int recv_own_msgs;
 218         struct sockaddr_can addr;
 219         struct ifreq ifr;
 220         struct can_filter fi;
 221
 222         s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
 223         if (s < 0) {
 224                 perror("socket");
 225                 exit(1);
 226         }
 227
 228         /* Convert interface name to index */
 229         memset(&ifr.ifr_name, 0, sizeof(ifr.ifr_name));
 230         strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
 231         if (ioctl(s, SIOCGIFINDEX, &ifr) < 0) {
 232                 perror("SIOCGIFINDEX");
 233                 exit(1);
 234         }
 235
 236         /* Open the CAN interface */
 237         memset(&addr, 0, sizeof(addr));
 238         addr.can_family = AF_CAN;
 239         addr.can_ifindex = ifr.ifr_ifindex;
 240         if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
 241                 perror("bind");
 242                 return 0;
 243         }
 244
 245         recv_own_msgs = 1; /* 0 = disabled (default), 1 = enabled */
 246         setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
 247                         &recv_own_msgs, sizeof(recv_own_msgs));
 248
 249         /* Handle only 32 NM IDs at CAN base ID 0x420 */
 250         fi.can_id   = 0x420;
 251         fi.can_mask = 0x7E0;
 252
 253         setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &fi, sizeof(struct can_filter));
 254
 255         return s;
 256 }
 257
 258
 259 int main(int argc, char **argv)
 260 {
 261         struct NM_Main *nm;
 262         fd_set rdfs;
 263         int s;
 264
 265         if (argc != 2) {
 266                 printf("syntax: %s IFNAME\n", argv[0]);
 267                 return 1;
 268         }
 269
 270         nm = nm_alloc(5, 0x0b, 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_start(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
 321         return 0;
 322 }