diff options
Diffstat (limited to 'pcap-linux.c')
| -rw-r--r-- | pcap-linux.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/pcap-linux.c b/pcap-linux.c index b7fb6889..f1ce0c61 100644 --- a/pcap-linux.c +++ b/pcap-linux.c @@ -1643,6 +1643,22 @@ linux_check_direction(const pcap_t *handle, const struct sockaddr_ll *sll) return 0; /* + * If this is an outgoing CAN or CAN FD frame, and + * the user doesn't only want outgoing packets, + * reject it; CAN devices and drivers, and the CAN + * stack, always arrange to loop back transmitted + * packets, so they also appear as incoming packets. + * We don't want duplicate packets, and we can't + * easily distinguish packets looped back by the CAN + * layer than those received by the CAN layer, so we + * eliminate this packet instead. + */ + if ((sll->sll_protocol == LINUX_SLL_P_CAN || + sll->sll_protocol == LINUX_SLL_P_CANFD) && + handle->direction != PCAP_D_OUT) + return 0; + + /* * If the user only wants incoming packets, reject it. */ if (handle->direction == PCAP_D_IN) |