]> rtime.felk.cvut.cz Git - can-utils.git/blobdiff - cangw.c
janitorial: log2asc: properly close infile and outfile
[can-utils.git] / cangw.c
diff --git a/cangw.c b/cangw.c
index 5e1ddc580c72bd3609a30568ff88263fd12f624e..b908fe45ddb59b0fbb59fb75c84c8d9bd7491588 100644 (file)
--- a/cangw.c
+++ b/cangw.c
@@ -1,7 +1,3 @@
-/*
- *  $Id$
- */
-
 /*
  * cangw.c - manage PF_CAN netlink gateway
  *
@@ -41,7 +37,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
  * DAMAGE.
  *
- * Send feedback to <socketcan-users@lists.berlios.de>
+ * Send feedback to <linux-can@vger.kernel.org>
  *
  */
 
@@ -50,6 +46,7 @@
 #include <libgen.h>
 #include <string.h>
 #include <unistd.h>
+#include <errno.h>
 #include <sys/socket.h>
 #include <net/if.h>
 #include <linux/netlink.h>
@@ -71,6 +68,9 @@ struct modattr {
 } __attribute__((packed));
 
 
+#define RTCAN_RTA(r)  ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct rtcanmsg))))
+#define RTCAN_PAYLOAD(n) NLMSG_PAYLOAD(n,sizeof(struct rtcanmsg))
+
 /* some netlink helpers stolen from iproute2 package */
 #define NLMSG_TAIL(nmsg) \
         ((struct rtattr *)(((void *) (nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))
@@ -94,22 +94,119 @@ int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
        return 0;
 }
 
+void printfilter(const void *data)
+{
+       struct can_filter *filter = (struct can_filter *)data;
+
+       if (filter->can_id & CAN_INV_FILTER)
+               printf("-f %03X~%X ", (filter->can_id & ~CAN_INV_FILTER), filter->can_mask);
+       else
+               printf("-f %03X:%X ", filter->can_id, filter->can_mask);
+}
+
+void printmod(const char *type, const void *data)
+{
+       struct modattr mod;
+       int i;
+
+       memcpy (&mod, data, CGW_MODATTR_LEN);
+
+       printf("-m %s:", type);
+
+       if (mod.modtype & CGW_MOD_ID)
+               printf("I");
+
+       if (mod.modtype & CGW_MOD_DLC)
+               printf("L");
+
+       if (mod.modtype & CGW_MOD_DATA)
+               printf("D");
+
+       printf(":%03X.%X.", mod.cf.can_id, mod.cf.can_dlc);
+
+       for (i = 0; i < 8; i++)
+               printf("%02X", mod.cf.data[i]);
+
+       printf(" ");
+}
+
+void print_cs_xor(struct cgw_csum_xor *cs_xor)
+{
+       printf("-x %d:%d:%d:%02X ",
+              cs_xor->from_idx, cs_xor->to_idx,
+              cs_xor->result_idx, cs_xor->init_xor_val);
+}
+
+void print_cs_crc8_profile(struct cgw_csum_crc8 *cs_crc8)
+{
+       int i;
+
+       printf("-p %d:", cs_crc8->profile);
+
+       switch (cs_crc8->profile) {
+
+       case  CGW_CRC8PRF_1U8:
+
+               printf("%02X", cs_crc8->profile_data[0]);
+               break;
+
+       case  CGW_CRC8PRF_16U8:
+
+               for (i = 0; i < 16; i++)
+                       printf("%02X", cs_crc8->profile_data[i]);
+               break;
+
+       case  CGW_CRC8PRF_SFFID_XOR:
+               break;
+
+       default:
+               printf("<unknown profile #%d>", cs_crc8->profile);
+       }
+
+       printf(" ");
+}
+
+void print_cs_crc8(struct cgw_csum_crc8 *cs_crc8)
+{
+       int i;
+
+       printf("-c %d:%d:%d:%02X:%02X:",
+              cs_crc8->from_idx, cs_crc8->to_idx,
+              cs_crc8->result_idx, cs_crc8->init_crc_val,
+              cs_crc8->final_xor_val);
+
+       for (i = 0; i < 256; i++)
+               printf("%02X", cs_crc8->crctab[i]);
+
+       printf(" ");
+
+       if (cs_crc8->profile != CGW_CRC8PRF_UNSPEC)
+               print_cs_crc8_profile(cs_crc8);
+}
+
 void print_usage(char *prg)
 {
        fprintf(stderr, "\nUsage: %s [options]\n\n", prg);
        fprintf(stderr, "Commands:  -A (add a new rule)\n");
-       fprintf(stderr, "           -D (delete a rule)             [not yet implemented]\n");
-       fprintf(stderr, "           -F (flush - delete all rules)  [not yet implemented]\n");
-       fprintf(stderr, "           -L (list all rules)            [not yet implemented]\n");
+       fprintf(stderr, "           -D (delete a rule)\n");
+       fprintf(stderr, "           -F (flush / delete all rules)\n");
+       fprintf(stderr, "           -L (list all rules)\n");
        fprintf(stderr, "Mandatory: -s <src_dev>  (source netdevice)\n");
        fprintf(stderr, "           -d <dst_dev>  (destination netdevice)\n");
        fprintf(stderr, "Options:   -t (preserve src_dev rx timestamp)\n");
        fprintf(stderr, "           -e (echo sent frames - recommended on vcanx)\n");
+       fprintf(stderr, "           -i (allow to route to incoming interface)\n");
+       fprintf(stderr, "           -l <hops> (limit the number of frame hops / routings)\n");
        fprintf(stderr, "           -f <filter> (set CAN filter)\n");
        fprintf(stderr, "           -m <mod> (set frame modifications)\n");
+       fprintf(stderr, "           -x <from_idx>:<to_idx>:<result_idx>:<init_xor_val> (XOR checksum)\n");
+       fprintf(stderr, "           -c <from>:<to>:<result>:<init_val>:<xor_val>:<crctab[256]> (CRC8 cs)\n");
+       fprintf(stderr, "           -p <profile>:[<profile_data>] (CRC8 checksum profile & parameters)\n");
        fprintf(stderr, "\nValues are given and expected in hexadecimal values. Leading 0s can be omitted.\n");
        fprintf(stderr, "\n");
-       fprintf(stderr, "<filter> is a <value>:<mask> CAN identifier filter\n");
+       fprintf(stderr, "<filter> is a <value><mask> CAN identifier filter\n");
+       fprintf(stderr, "   <can_id>:<can_mask> (matches when <received_can_id> & mask == can_id & mask)\n");
+       fprintf(stderr, "   <can_id>~<can_mask> (matches when <received_can_id> & mask != can_id & mask)\n");
        fprintf(stderr, "\n");
        fprintf(stderr, "<mod> is a CAN frame modification instruction consisting of\n");
        fprintf(stderr, "<instruction>:<can_frame-elements>:<can_id>.<can_dlc>.<can_data>\n");
@@ -118,18 +215,71 @@ void print_usage(char *prg)
        fprintf(stderr, " - <can_id> is an u32 value containing the CAN Identifier\n");
        fprintf(stderr, " - <can_dlc> is an u8 value containing the data length code (0 .. 8)\n");
        fprintf(stderr, " - <can_data> is always eight(!) u8 values containing the CAN frames data\n");
-       fprintf(stderr, "The instructions are performed in the order 'AND' -> 'OR' -> 'XOR' -> 'SET'\n");
+       fprintf(stderr, "The max. four modifications are performed in the order AND -> OR -> XOR -> SET\n");
        fprintf(stderr, "\n");
        fprintf(stderr, "Example:\n");
-       fprintf(stderr, "%s -A -s can0 -d vcan3 -f 123:C00007FF -m SET:IL:80000333.4.1122334455667788\n", prg);
+       fprintf(stderr, "%s -A -s can0 -d vcan3 -e -f 123:C00007FF -m SET:IL:333.4.1122334455667788\n", prg);
+       fprintf(stderr, "\n");
+       fprintf(stderr, "Supported CRC 8 profiles:\n");
+       fprintf(stderr, "Profile '%d' (1U8)       - add one additional u8 value\n", CGW_CRC8PRF_1U8);
+       fprintf(stderr, "Profile '%d' (16U8)      - add u8 value from table[16] indexed by (data[1] & 0xF)\n", CGW_CRC8PRF_16U8);
+       fprintf(stderr, "Profile '%d' (SFFID_XOR) - add u8 value (can_id & 0xFF) ^ (can_id >> 8 & 0xFF)\n", CGW_CRC8PRF_SFFID_XOR);
        fprintf(stderr, "\n");
 }
 
-int parse_mod(char *optarg, struct modattr *modmsg)
+int b64hex(char *asc, unsigned char *bin, int len)
 {
-       char *ptr, *nptr;
        int i;
 
+       for (i = 0; i < len; i++) {
+               if (!sscanf(asc+(i*2), "%2hhx", bin+i))
+                       return 1;       
+       }
+       return 0;
+}
+
+int parse_crc8_profile(char *optarg, struct cgw_csum_crc8 *crc8)
+{
+       int ret = 1;
+       char *ptr;
+
+       if (sscanf(optarg, "%hhd:", &crc8->profile) != 1)
+               return ret;
+
+       switch (crc8->profile) {
+
+       case  CGW_CRC8PRF_1U8:
+
+               if (sscanf(optarg, "%hhd:%2hhx", &crc8->profile, &crc8->profile_data[0]) == 2)
+                       ret = 0;
+
+               break;
+
+       case  CGW_CRC8PRF_16U8:
+
+               ptr = strchr(optarg, ':');
+
+               /* check if length contains 16 base64 hex values */
+               if (ptr != NULL &&
+                   strlen(ptr) == strlen(":00112233445566778899AABBCCDDEEFF") &&
+                   b64hex(ptr+1, (unsigned char *)&crc8->profile_data[0], 16) == 0)
+                       ret = 0;
+
+               break;
+
+       case  CGW_CRC8PRF_SFFID_XOR:
+
+               /* no additional parameters needed */
+               ret = 0;
+               break;
+       }
+
+       return ret;
+}
+
+int parse_mod(char *optarg, struct modattr *modmsg)
+{
+       char *ptr, *nptr;
        char hexdata[17] = {0};
 
        ptr = optarg;
@@ -179,23 +329,203 @@ int parse_mod(char *optarg, struct modattr *modmsg)
                ptr++;
        }
 
-       if ((sscanf(++ptr, "%lx.%hhd.%16s",
-                   (long unsigned int *)&modmsg->cf.can_id,
-                   (unsigned char *)&modmsg->cf.can_dlc, hexdata) != 3) ||
-           (modmsg->cf.can_dlc > 8))
+       if (sscanf(++ptr, "%x.%hhx.%16s", &modmsg->cf.can_id,
+                  (unsigned char *)&modmsg->cf.can_dlc, hexdata) != 3)
                return 5;
 
-       if (strlen(hexdata) != 16)
+       /* 4-bit masks can have values from 0 to 0xF */ 
+       if (modmsg->cf.can_dlc > 0xF)
                return 6;
 
-       for (i = 0; i < 8; i++) {
-               if (!sscanf(&hexdata[i*2], "%2hhx", &modmsg->cf.data[i]))
-                       return 7;       
-       }
+       /* but when setting CAN_DLC the value has to be limited to 8 */
+       if (modmsg->instruction == CGW_MOD_SET && modmsg->cf.can_dlc > 8)
+               return 7;
+
+       if (strlen(hexdata) != 16)
+               return 8;
+
+       if (b64hex(hexdata, &modmsg->cf.data[0], 8))
+               return 9;
 
        return 0; /* ok */
 }
 
+int parse_rtlist(char *prgname, unsigned char *rxbuf, int len)
+{
+       char ifname[IF_NAMESIZE]; /* internface name for if_indextoname() */
+       struct rtcanmsg *rtc;
+       struct rtattr *rta;
+       struct nlmsghdr *nlh;
+       unsigned int src_ifindex = 0;
+       unsigned int dst_ifindex = 0;
+       __u32 handled, dropped, deleted;
+       int rtlen;
+
+
+       nlh = (struct nlmsghdr *)rxbuf;
+
+       while (1) {
+               if (!NLMSG_OK(nlh, len))
+                       return 0;
+
+               if (nlh->nlmsg_type == NLMSG_ERROR) {
+                       printf("NLMSG_ERROR\n");
+                       return 1;
+               }
+
+               if (nlh->nlmsg_type == NLMSG_DONE) {
+                       //printf("NLMSG_DONE\n");
+                       return 1;
+               }
+
+               rtc = (struct rtcanmsg *)NLMSG_DATA(nlh);
+               if (rtc->can_family != AF_CAN) {
+                       printf("received msg from unknown family %d\n", rtc->can_family);
+                       return -EINVAL;
+               }
+
+               if (rtc->gwtype != CGW_TYPE_CAN_CAN) {
+                       printf("received msg with unknown gwtype %d\n", rtc->gwtype);
+                       return -EINVAL;
+               }
+
+               /*
+                * print list in a representation that
+                * can be used directly for start scripts.
+                *
+                * To order the mandatory and optional parameters in the
+                * output string, the NLMSG is parsed twice.
+                */
+
+               handled = 0;
+               dropped = 0;
+               deleted = 0;
+               src_ifindex = 0;
+               dst_ifindex = 0;
+
+               printf("%s -A ", basename(prgname));
+
+               /* first parse for mandatory options */
+               rta = (struct rtattr *) RTCAN_RTA(rtc);
+               rtlen = RTCAN_PAYLOAD(nlh);
+               for(;RTA_OK(rta, rtlen);rta=RTA_NEXT(rta,rtlen))
+               {
+                       //printf("(A-%d)", rta->rta_type);
+                       switch(rta->rta_type) {
+
+                       case CGW_FILTER:
+                       case CGW_MOD_AND:
+                       case CGW_MOD_OR:
+                       case CGW_MOD_XOR:
+                       case CGW_MOD_SET:
+                       case CGW_LIM_HOPS:
+                       case CGW_CS_XOR:
+                       case CGW_CS_CRC8:
+                               break;
+
+                       case CGW_SRC_IF:
+                               src_ifindex = *(__u32 *)RTA_DATA(rta);
+                               break;
+
+                       case CGW_DST_IF:
+                               dst_ifindex = *(__u32 *)RTA_DATA(rta);
+                               break;
+
+                       case CGW_HANDLED:
+                               handled = *(__u32 *)RTA_DATA(rta);
+                               break;
+
+                       case CGW_DROPPED:
+                               dropped = *(__u32 *)RTA_DATA(rta);
+                               break;
+
+                       case CGW_DELETED:
+                               deleted = *(__u32 *)RTA_DATA(rta);
+                               break;
+
+                       default:
+                               printf("Unknown attribute %d!", rta->rta_type);
+                               return -EINVAL;
+                               break;
+                       }
+               }
+
+
+               printf("-s %s ", if_indextoname(src_ifindex, ifname));
+               printf("-d %s ", if_indextoname(dst_ifindex, ifname));
+
+               if (rtc->flags & CGW_FLAGS_CAN_ECHO)
+                       printf("-e ");
+
+               if (rtc->flags & CGW_FLAGS_CAN_SRC_TSTAMP)
+                       printf("-t ");
+
+               if (rtc->flags & CGW_FLAGS_CAN_IIF_TX_OK)
+                       printf("-i ");
+
+               /* second parse for mod attributes */
+               rta = (struct rtattr *) RTCAN_RTA(rtc);
+               rtlen = RTCAN_PAYLOAD(nlh);
+               for(;RTA_OK(rta, rtlen);rta=RTA_NEXT(rta,rtlen))
+               {
+                       //printf("(B-%d)", rta->rta_type);
+                       switch(rta->rta_type) {
+
+                       case CGW_FILTER:
+                               printfilter(RTA_DATA(rta));
+                               break;
+
+                       case CGW_MOD_AND:
+                               printmod("AND", RTA_DATA(rta));
+                               break;
+
+                       case CGW_MOD_OR:
+                               printmod("OR", RTA_DATA(rta));
+                               break;
+
+                       case CGW_MOD_XOR:
+                               printmod("XOR", RTA_DATA(rta));
+                               break;
+
+                       case CGW_MOD_SET:
+                               printmod("SET", RTA_DATA(rta));
+                               break;
+
+                       case CGW_LIM_HOPS:
+                               printf("-l %d ", *(__u8 *)RTA_DATA(rta));
+                               break;
+
+                       case CGW_CS_XOR:
+                               print_cs_xor((struct cgw_csum_xor *)RTA_DATA(rta));
+                               break;
+
+                       case CGW_CS_CRC8:
+                               print_cs_crc8((struct cgw_csum_crc8 *)RTA_DATA(rta));
+                               break;
+
+                       case CGW_SRC_IF:
+                       case CGW_DST_IF:
+                       case CGW_HANDLED:
+                       case CGW_DROPPED:
+                       case CGW_DELETED:
+                               break;
+
+                       default:
+                               printf("Unknown attribute %d!", rta->rta_type);
+                               return -EINVAL;
+                               break;
+                       }
+               }
+
+               /* end of entry */
+               printf("# %d handled %d dropped %d deleted\n",
+                      handled, dropped, deleted);
+
+               /* jump to next NLMSG in the given buffer */
+               nlh = NLMSG_NEXT(nlh, len);
+       }
+}
+
 int main(int argc, char **argv)
 {
        int s;
@@ -206,24 +536,41 @@ int main(int argc, char **argv)
 
        int cmd = UNSPEC;
        int have_filter = 0;
+       int have_cs_xor = 0;
+       int have_cs_crc8 = 0;
 
        struct {
-               struct nlmsghdr n;
-               struct rtcanmsg r;
-               char buf[200];
+               struct nlmsghdr nh;
+               struct rtcanmsg rtcan;
+               char buf[600];
 
        } req;
 
+       unsigned char rxbuf[8192]; /* netlink receive buffer */
+       struct nlmsghdr *nlh;
+       struct nlmsgerr *rte;
+       unsigned int src_ifindex = 0;
+       unsigned int dst_ifindex = 0;
+       __u8 limit_hops = 0;
+       __u16 flags = 0;
+       int len;
+
        struct can_filter filter;
        struct sockaddr_nl nladdr;
 
+       struct cgw_csum_xor cs_xor;
+       struct cgw_csum_crc8 cs_crc8;
+       char crc8tab[513] = {0};
+
        struct modattr modmsg[CGW_MOD_FUNCS];
        int modidx = 0;
        int i;
 
        memset(&req, 0, sizeof(req));
+       memset(&cs_xor, 0, sizeof(cs_xor));
+       memset(&cs_crc8, 0, sizeof(cs_crc8));
 
-       while ((opt = getopt(argc, argv, "ADFLs:d:tef:m:?")) != -1) {
+       while ((opt = getopt(argc, argv, "ADFLs:d:teil:f:c:p:x:m:?")) != -1) {
                switch (opt) {
 
                case 'A':
@@ -247,25 +594,39 @@ int main(int argc, char **argv)
                        break;
 
                case 's':
-                       req.r.src_ifindex = if_nametoindex(optarg);
+                       src_ifindex = if_nametoindex(optarg);
                        break;
 
                case 'd':
-                       req.r.dst_ifindex = if_nametoindex(optarg);
+                       dst_ifindex = if_nametoindex(optarg);
                        break;
 
                case 't':
-                       req.r.can_txflags |= CAN_GW_TXFLAGS_SRC_TSTAMP;
+                       flags |= CGW_FLAGS_CAN_SRC_TSTAMP;
                        break;
 
                case 'e':
-                       req.r.can_txflags |= CAN_GW_TXFLAGS_ECHO;
+                       flags |= CGW_FLAGS_CAN_ECHO;
+                       break;
+
+               case 'i':
+                       flags |= CGW_FLAGS_CAN_IIF_TX_OK;
+                       break;
+
+               case 'l':
+                       if (sscanf(optarg, "%hhd", &limit_hops) != 1 || !(limit_hops)) {
+                               printf("Bad hop limit definition '%s'.\n", optarg);
+                               exit(1);
+                       }
                        break;
 
                case 'f':
-                       if (sscanf(optarg, "%lx:%lx",
-                                  (long unsigned int *)&filter.can_id, 
-                                  (long unsigned int *)&filter.can_mask) == 2) {
+                       if (sscanf(optarg, "%x:%x", &filter.can_id,
+                                  &filter.can_mask) == 2) {
+                               have_filter = 1;
+                       } else if (sscanf(optarg, "%x~%x", &filter.can_id,
+                                         &filter.can_mask) == 2) {
+                               filter.can_id |= CAN_INV_FILTER;
                                have_filter = 1;
                        } else {
                                printf("Bad filter definition '%s'.\n", optarg);
@@ -273,6 +634,38 @@ int main(int argc, char **argv)
                        }
                        break;
 
+               case 'x':
+                       if (sscanf(optarg, "%hhd:%hhd:%hhd:%hhx",
+                                  &cs_xor.from_idx, &cs_xor.to_idx,
+                                  &cs_xor.result_idx, &cs_xor.init_xor_val) == 4) {
+                               have_cs_xor = 1;
+                       } else {
+                               printf("Bad XOR checksum definition '%s'.\n", optarg);
+                               exit(1);
+                       }
+                       break;
+
+               case 'c':
+                       if ((sscanf(optarg, "%hhd:%hhd:%hhd:%hhx:%hhx:%512s",
+                                   &cs_crc8.from_idx, &cs_crc8.to_idx,
+                                   &cs_crc8.result_idx, &cs_crc8.init_crc_val,
+                                   &cs_crc8.final_xor_val, crc8tab) == 6) &&
+                           (strlen(crc8tab) == 512) &&
+                           (b64hex(crc8tab, (unsigned char *)&cs_crc8.crctab, 256) == 0)) {
+                               have_cs_crc8 = 1;
+                       } else {
+                               printf("Bad CRC8 checksum definition '%s'.\n", optarg);
+                               exit(1);
+                       }
+                       break;
+
+               case 'p':
+                       if (parse_crc8_profile(optarg, &cs_crc8)) {
+                               printf("Bad CRC8 profile definition '%s'.\n", optarg);
+                               exit(1);
+                       }
+                       break;
+
                case 'm':
                        /* may be triggered by each of the CGW_MOD_FUNCS functions */
                        if ((modidx < CGW_MOD_FUNCS) && (err = parse_mod(optarg, &modmsg[modidx++]))) {
@@ -294,19 +687,47 @@ int main(int argc, char **argv)
                }
        }
 
-       if ((argc - optind != 0) || (cmd == UNSPEC) ||
-           (!req.r.src_ifindex) || (!req.r.dst_ifindex)) {
+       if ((argc - optind != 0) || (cmd == UNSPEC)) {
+               print_usage(basename(argv[0]));
+               exit(1);
+       }
+
+       if ((cmd == ADD || cmd == DEL) &&
+           ((!src_ifindex) || (!dst_ifindex))) {
                print_usage(basename(argv[0]));
                exit(1);
        }
 
+       if (!modidx && (have_cs_crc8 || have_cs_xor)) {
+               printf("-c or -x can only be used in conjunction with -m\n");
+               exit(1);
+       }
+
        s = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
 
        switch (cmd) {
 
        case ADD:
-               req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL;
-               req.n.nlmsg_type  = RTM_NEWROUTE;
+               req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+               req.nh.nlmsg_type  = RTM_NEWROUTE;
+               break;
+
+       case DEL:
+               req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+               req.nh.nlmsg_type  = RTM_DELROUTE;
+               break;
+
+       case FLUSH:
+               req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+               req.nh.nlmsg_type  = RTM_DELROUTE;
+               /* if_index set to 0 => remove all entries */
+               src_ifindex  = 0;
+               dst_ifindex  = 0;
+               break;
+
+       case LIST:
+               req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
+               req.nh.nlmsg_type  = RTM_GETROUTE;
                break;
 
        default:
@@ -315,34 +736,101 @@ int main(int argc, char **argv)
                break;
        }
 
-       req.n.nlmsg_len   = NLMSG_LENGTH(sizeof(struct rtcanmsg));
-       req.n.nlmsg_seq   = 0;
+       req.nh.nlmsg_len   = NLMSG_LENGTH(sizeof(struct rtcanmsg));
+       req.nh.nlmsg_seq   = 0;
+
+       req.rtcan.can_family  = AF_CAN;
+       req.rtcan.gwtype = CGW_TYPE_CAN_CAN;
+       req.rtcan.flags = flags;
 
-       req.r.can_family  = AF_CAN;
+       addattr_l(&req.nh, sizeof(req), CGW_SRC_IF, &src_ifindex, sizeof(src_ifindex));
+       addattr_l(&req.nh, sizeof(req), CGW_DST_IF, &dst_ifindex, sizeof(dst_ifindex));
 
        /* add new attributes here */
 
        if (have_filter)
-               addattr_l(&req.n, sizeof(req), CGW_FILTER, &filter, sizeof(filter));
+               addattr_l(&req.nh, sizeof(req), CGW_FILTER, &filter, sizeof(filter));
+
+       if (have_cs_crc8)
+               addattr_l(&req.nh, sizeof(req), CGW_CS_CRC8, &cs_crc8, sizeof(cs_crc8));
 
-       // a better example code
-       // modmsg.modtype = CGW_MOD_ID;
-       // addattr_l(&req.n, sizeof(req), CGW_MOD_SET, &modmsg, CGW_MODATTR_LEN);
+       if (have_cs_xor)
+               addattr_l(&req.nh, sizeof(req), CGW_CS_XOR, &cs_xor, sizeof(cs_xor));
+
+       if (limit_hops)
+               addattr_l(&req.nh, sizeof(req), CGW_LIM_HOPS, &limit_hops, sizeof(__u8));
+
+       /*
+        * a better example code
+        * modmsg.modtype = CGW_MOD_ID;
+        * addattr_l(&req.n, sizeof(req), CGW_MOD_SET, &modmsg, CGW_MODATTR_LEN);
+        */
 
        /* add up to CGW_MOD_FUNCS modification definitions */
        for (i = 0; i < modidx; i++)
-               addattr_l(&req.n, sizeof(req), modmsg[i].instruction, &modmsg[i], CGW_MODATTR_LEN);
+               addattr_l(&req.nh, sizeof(req), modmsg[i].instruction, &modmsg[i], CGW_MODATTR_LEN);
 
        memset(&nladdr, 0, sizeof(nladdr));
        nladdr.nl_family = AF_NETLINK;
        nladdr.nl_pid    = 0;
        nladdr.nl_groups = 0;
 
-       err = sendto(s, &req, req.n.nlmsg_len, 0,
+       err = sendto(s, &req, req.nh.nlmsg_len, 0,
                     (struct sockaddr*)&nladdr, sizeof(nladdr));
+       if (err < 0) {
+               perror("netlink sendto");
+               return err;
+       }
+
+       /* clean netlink receive buffer */
+       memset(rxbuf, 0x0, sizeof(rxbuf));
+
+       if (cmd != LIST) {
 
-       if (err < 0)
-               perror("PF_CAN netlink gateway answered ");
+               /*
+                * cmd == ADD || cmd == DEL || cmd == FLUSH
+                *
+                * Parse the requested netlink acknowledge return values.
+                */
+
+               err = recv(s, &rxbuf, sizeof(rxbuf), 0);
+               if (err < 0) {
+                       perror("netlink recv");
+                       return err;
+               }
+               nlh = (struct nlmsghdr *)rxbuf;
+               if (nlh->nlmsg_type != NLMSG_ERROR) {
+                       fprintf(stderr, "unexpected netlink answer of type %d\n", nlh->nlmsg_type);
+                       return -EINVAL;
+               }
+               rte = (struct nlmsgerr *)NLMSG_DATA(nlh);
+               err = rte->error;
+               if (err < 0)
+                       fprintf(stderr, "netlink error %d (%s)\n", err, strerror(abs(err)));
+
+       } else {
+
+               /* cmd == LIST */
+
+               while (1) {
+                       len = recv(s, &rxbuf, sizeof(rxbuf), 0);
+                       if (len < 0) {
+                               perror("netlink recv");
+                               return len;
+                       }
+#if 0
+                       printf("received msg len %d\n", len);
+
+                       for (i = 0; i < len; i++)
+                               printf("%02X ", rxbuf[i]);
+
+                       printf("\n");
+#endif
+                       /* leave on errors or NLMSG_DONE */
+                       if (parse_rtlist(argv[0], rxbuf, len))
+                               break;
+               }
+       }
 
        close(s);