cangw: add an option for the per rule limitation of frame hops

Usually the received CAN frames can be processed/routed as much as 'max_hops'
times (which is given at module load time of the can-gw module).
Introduce a new configuration option ( -l <hops> ) to reduce the number of
possible hops for a specific gateway rule to a value smaller then max_hops.

Mainline upstream commit:

http://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=391ac1282dd7ff1cb8245cccc5262e8e4173edc4

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>

diff --git a/cangw.c b/cangw.c
index 802aa86..b908fe4 100644 (file)
--- a/cangw.c
+++ b/cangw.c
@@ -196,6 +196,7 @@ void print_usage(char *prg)
        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");
@@ -417,6 +418,7 @@ int parse_rtlist(char *prgname, unsigned char *rxbuf, int len)
                        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;
@@ -489,6 +491,10 @@ int parse_rtlist(char *prgname, unsigned char *rxbuf, int len)
                                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;
@@ -545,6 +551,7 @@ int main(int argc, char **argv)
        struct nlmsgerr *rte;
        unsigned int src_ifindex = 0;
        unsigned int dst_ifindex = 0;
+       __u8 limit_hops = 0;
        __u16 flags = 0;
        int len;
 
@@ -563,7 +570,7 @@ int main(int argc, char **argv)
        memset(&cs_xor, 0, sizeof(cs_xor));
        memset(&cs_crc8, 0, sizeof(cs_crc8));
 
-       while ((opt = getopt(argc, argv, "ADFLs:d:teif:c:p:x:m:?")) != -1) {
+       while ((opt = getopt(argc, argv, "ADFLs:d:teil:f:c:p:x:m:?")) != -1) {
                switch (opt) {
 
                case 'A':
@@ -606,6 +613,13 @@ int main(int argc, char **argv)
                        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, "%x:%x", &filter.can_id,
                                   &filter.can_mask) == 2) {
@@ -743,6 +757,9 @@ int main(int argc, char **argv)
        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;

diff --git a/include/socketcan/can/gw.h b/include/socketcan/can/gw.h
index 9c290dc..56d3246 100644 (file)
--- a/include/socketcan/can/gw.h
+++ b/include/socketcan/can/gw.h
@@ -45,6 +45,7 @@ enum {
        CGW_DST_IF,     /* ifindex of destination network interface */
        CGW_FILTER,     /* specify struct can_filter on source CAN device */
        CGW_DELETED,    /* number of deleted CAN frames (see max_hops param) */
+       CGW_LIM_HOPS,   /* limit the number of hops of this specific rule */
        __CGW_MAX
 };
 
@@ -116,13 +117,19 @@ enum {
  * Sets a CAN receive filter for the gateway job specified by the
  * struct can_filter described in include/linux/can.h
  *
- * CGW_MOD_XXX (length 17 bytes):
+ * CGW_MOD_(AND|OR|XOR|SET) (length 17 bytes):
  * Specifies a modification that's done to a received CAN frame before it is
  * send out to the destination interface.
  *
  * <struct can_frame> data used as operator
  * <u8> affected CAN frame elements
  *
+ * CGW_LIM_HOPS (length 1 byte):
+ * Limit the number of hops of this specific rule. Usually the received CAN
+ * frame can be processed as much as 'max_hops' times (which is given at module
+ * load time of the can-gw module). This value is used to reduce the number of
+ * possible hops for this gateway job to a value smaller then max_hops.
+ *
  * CGW_CS_XOR (length 4 bytes):
  * Set a simple XOR checksum starting with an initial value into
  * data[result-idx] using data[start-idx] .. data[end-idx]