diff options
| -rw-r--r-- | pcap-linux.c | 44 |
1 files changed, 36 insertions, 8 deletions
diff --git a/pcap-linux.c b/pcap-linux.c index 949895e9..9a5d98d5 100644 --- a/pcap-linux.c +++ b/pcap-linux.c @@ -303,7 +303,7 @@ typedef int socklen_t; */ struct pcap_linux { u_int packets_read; /* count of packets read with recvfrom() */ - long sysfs_dropped; /* packets reported dropped by /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors */ + long long sysfs_dropped; /* packets reported dropped by /sys/class/net/{if_name}/statistics/rx_{missed,fifo}_errors */ struct pcap_stat stat; char *device; /* device name */ @@ -1179,7 +1179,7 @@ pcap_can_set_rfmon_linux(pcap_t *handle) * but may be unimplemented and just return 0. * The author has found no straigthforward way to check for support. */ -static long int +static long long int linux_get_stat(const char * if_name, const char * stat) { ssize_t bytes_read; int fd; @@ -1196,14 +1196,14 @@ linux_get_stat(const char * if_name, const char * stat) { return 0; buffer[bytes_read] = '\0'; - return strtol(buffer, NULL, 10); + return strtoll(buffer, NULL, 10); } -static long int +static long long int linux_if_drops(const char * if_name) { - long int missed = linux_get_stat(if_name, "rx_missed_errors"); - long int fifo = linux_get_stat(if_name, "rx_fifo_errors"); + long long int missed = linux_get_stat(if_name, "rx_missed_errors"); + long long int fifo = linux_get_stat(if_name, "rx_fifo_errors"); return missed + fifo; } @@ -2335,7 +2335,7 @@ pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) socklen_t len = sizeof (struct tpacket_stats); #endif /* HAVE_STRUCT_TPACKET_STATS */ - long if_dropped = 0; + long long if_dropped = 0; /* * To fill in ps_ifdrop, we parse @@ -2344,9 +2344,37 @@ pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats) */ if (handle->opt.promisc) { + /* + * XXX - is there any reason to do this by remembering + * the last counts value, subtracting it from the + * current counts value, and adding that to stat.ps_ifdrop, + * maintaining stat.ps_ifdrop as a count, rather than just + * saving the *initial* counts value and setting + * stat.ps_ifdrop to the difference between the current + * value and the initial value? + * + * One reason might be to handle the count wrapping + * around, on platforms where the count is 32 bits + * and where you might get more than 2^32 dropped + * packets; is there any other reason? + * + * (We maintain the count as a long long int so that, + * if the kernel maintains the counts as 64-bit even + * on 32-bit platforms, we can handle the real count. + * + * Unfortunately, we can't report 64-bit counts; we + * need a better API for reporting statistics, such as + * one that reports them in a style similar to the + * pcapng Interface Statistics Block, so that 1) the + * counts are 64-bit, 2) it's easier to add new statistics + * without breaking the ABI, and 3) it's easier to + * indicate to a caller that wants one particular + * statistic that it's not available by just not supplying + * it.) + */ if_dropped = handlep->sysfs_dropped; handlep->sysfs_dropped = linux_if_drops(handlep->device); - handlep->stat.ps_ifdrop += (handlep->sysfs_dropped - if_dropped); + handlep->stat.ps_ifdrop += (u_int)(handlep->sysfs_dropped - if_dropped); } #ifdef HAVE_STRUCT_TPACKET_STATS |