+/********************************************************************
+ * get_ppp_stats_rtnetlink - return statistics for the link, using rtnetlink
+ * This provides native 64-bit counters.
+ */
+static int
+get_ppp_stats_rtnetlink(int u, struct pppd_stats *stats)
+{
+ static int fd = -1;
+
+ struct {
+ struct nlmsghdr nlh;
+ struct if_stats_msg ifsm;
+ } nlreq;
+ struct {
+ struct rtmsg rth;
+ struct {
+ /* We only case about these first fields from rtnl_link_stats64 */
+ uint64_t rx_packets;
+ uint64_t tx_packets;
+ uint64_t rx_bytes;
+ uint64_t tx_bytes;
+ } stats;
+ } nlresp_data;
+ size_t nlresp_size;
+ int resp;
+
+ memset(&nlreq, 0, sizeof(nlreq));
+ nlreq.nlh.nlmsg_len = sizeof(nlreq);
+ nlreq.nlh.nlmsg_type = RTM_GETSTATS;
+ nlreq.nlh.nlmsg_flags = NLM_F_REQUEST;
+ nlreq.ifsm.ifindex = if_nametoindex(ifname);
+ nlreq.ifsm.filter_mask = IFLA_STATS_LINK_64;
+
+ nlresp_size = sizeof(nlresp_data);
+ resp = rtnetlink_msg("RTM_GETSTATS/NLM_F_REQUEST", &fd, &nlreq, sizeof(nlreq), &nlresp_data, &nlresp_size, RTM_NEWSTATS);
+ if (resp) {
+ errno = (resp < 0) ? -resp : EINVAL;
+ if (kernel_version >= KVERSION(4,7,0))
+ error("get_ppp_stats_rtnetlink: %m (line %d)", __LINE__);
+ goto err;
+ }
+
+ if (nlresp_size < sizeof(nlresp_data)) {
+ error("get_ppp_stats_rtnetlink: Obtained an insufficiently sized rtnl_link_stats64 struct from the kernel (line %d).", __LINE__);
+ goto err;
+ }
+
+ stats->bytes_in = nlresp_data.stats.rx_bytes;
+ stats->bytes_out = nlresp_data.stats.tx_bytes;
+ stats->pkts_in = nlresp_data.stats.rx_packets;
+ stats->pkts_out = nlresp_data.stats.tx_packets;
+
+ return 1;
+err:
+ close(fd);
+ fd = -1;
+ return 0;
+}
+
+/********************************************************************
+ * get_ppp_stats_sysfs - return statistics for the link, using the files in sysfs,
+ * this provides native 64-bit counters.
+ */
+static int
+get_ppp_stats_sysfs(int u, struct pppd_stats *stats)
+{
+ char fname[PATH_MAX+1];
+ char buf[21], *err; /* 2^64 < 10^20 */
+ int blen, fd, rlen;
+ unsigned long long val;
+
+ struct {
+ const char* fname;
+ void* ptr;
+ unsigned size;
+ } slist[] = {
+#define statfield(fn, field) { .fname = #fn, .ptr = &stats->field, .size = sizeof(stats->field) }
+ statfield(rx_bytes, bytes_in),
+ statfield(tx_bytes, bytes_out),
+ statfield(rx_packets, pkts_in),
+ statfield(tx_packets, pkts_out),
+#undef statfield
+ };
+
+ blen = snprintf(fname, sizeof(fname), "/sys/class/net/%s/statistics/", ifname);
+ if (blen >= sizeof(fname))
+ return 0; /* ifname max 15, so this should be impossible */
+
+ for (int i = 0; i < sizeof(slist) / sizeof(*slist); ++i) {
+ if (snprintf(fname + blen, sizeof(fname) - blen, "%s", slist[i].fname) >= sizeof(fname) - blen) {
+ fname[blen] = 0;
+ error("sysfs stats: filename %s/%s overflowed PATH_MAX", fname, slist[i].fname);
+ return 0;
+ }
+
+ fd = open(fname, O_RDONLY);
+ if (fd < 0) {
+ error("%s: %m", fname);
+ return 0;
+ }
+
+ rlen = read(fd, buf, sizeof(buf) - 1);
+ close(fd);
+ if (rlen < 0) {
+ error("%s: %m", fname);
+ return 0;
+ }
+ /* trim trailing \n if present */
+ while (rlen > 0 && buf[rlen-1] == '\n')
+ rlen--;
+ buf[rlen] = 0;
+
+ errno = 0;
+ val = strtoull(buf, &err, 10);
+ if (*buf < '0' || *buf > '9' || errno != 0 || *err) {
+ error("string to number conversion error converting %s (from %s) for remaining string %s%s%s",
+ buf, fname, err, errno ? ": " : "", errno ? strerror(errno) : "");
+ return 0;
+ }
+ switch (slist[i].size) {
+#define stattype(type) case sizeof(type): *(type*)slist[i].ptr = (type)val; break
+ stattype(uint64_t);
+ stattype(uint32_t);
+ stattype(uint16_t);
+ stattype(uint8_t);
+#undef stattype
+ default:
+ error("Don't know how to store stats for %s of size %u", slist[i].fname, slist[i].size);
+ return 0;
+ }
+ }
+
+ return 1;
+}
+
+/********************************************************************
+ * Periodic timer function to be used to keep stats up to date in case of ioctl
+ * polling.
+ *
+ * Given the 25s interval this should be fine up to data rates of 1.37Gbps.
+ * If you do change the timer, remember to also bring the get_ppp_stats (which
+ * sets up the initial trigger) as well.
+ */
+static void
+ppp_stats_poller(void* u)
+{
+ struct pppd_stats dummy;
+ get_ppp_stats_ioctl((long)u, &dummy);
+ TIMEOUT(ppp_stats_poller, u, 25);
+}
+
+/********************************************************************
+ * get_ppp_stats - return statistics for the link.
+ */
+int get_ppp_stats(int u, struct pppd_stats *stats)
+{
+ static int (*func)(int, struct pppd_stats*) = NULL;
+
+ if (!func) {
+ if (get_ppp_stats_rtnetlink(u, stats)) {
+ func = get_ppp_stats_rtnetlink;
+ return 1;
+ }
+ if (get_ppp_stats_sysfs(u, stats)) {
+ func = get_ppp_stats_sysfs;
+ return 1;
+ }
+ warn("statistics falling back to ioctl which only supports 32-bit counters");
+ func = get_ppp_stats_ioctl;
+ TIMEOUT(ppp_stats_poller, (void*)(long)u, 25);
+ }
+
+ return func(u, stats);
+}
+