+
+ generic_disestablish_ppp(tty_fd);
+}
+
+/********************************************************************
+ *
+ * generic_disestablish_ppp - Restore device components to normal
+ * operation, and reconnect the ppp unit to the loopback if in demand
+ * mode. This shouldn't call die() because it's called from die().
+ */
+void generic_disestablish_ppp(int dev_fd)
+{
+ if (new_style_driver) {
+ close(ppp_fd);
+ ppp_fd = -1;
+ if (demand) {
+ modify_flags(ppp_dev_fd, 0, SC_LOOP_TRAFFIC);
+ looped = 1;
+ } else if (!doing_multilink && ppp_dev_fd >= 0) {
+ close(ppp_dev_fd);
+ remove_fd(ppp_dev_fd);
+ ppp_dev_fd = -1;
+ }
+ } else {
+ /* old-style driver */
+ if (demand)
+ set_ppp_fd(slave_fd);
+ else
+ ppp_dev_fd = -1;
+ }
+}
+
+/*
+ * make_ppp_unit_rtnetlink - register a new ppp network interface for ppp_dev_fd
+ * with specified req_ifname via rtnetlink. Interface name req_ifname must not
+ * be empty. Custom ppp unit id req_unit is ignored and kernel choose some free.
+ */
+static int make_ppp_unit_rtnetlink(void)
+{
+ struct {
+ struct nlmsghdr nlh;
+ struct ifinfomsg ifm;
+ struct {
+ struct rtattr rta;
+ char ifname[IFNAMSIZ];
+ } ifn;
+ struct {
+ struct rtattr rta;
+ struct {
+ struct rtattr rta;
+ char ifkind[sizeof("ppp")];
+ } ifik;
+ struct {
+ struct rtattr rta;
+ struct {
+ struct rtattr rta;
+ union {
+ int ppp_dev_fd;
+ } ppp;
+ } ifdata[1];
+ } ifid;
+ } ifli;
+ } nlreq;
+ int resp;
+
+ memset(&nlreq, 0, sizeof(nlreq));
+ nlreq.nlh.nlmsg_len = sizeof(nlreq);
+ nlreq.nlh.nlmsg_type = RTM_NEWLINK;
+ nlreq.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_EXCL | NLM_F_CREATE;
+ nlreq.ifm.ifi_family = AF_UNSPEC;
+ nlreq.ifm.ifi_type = ARPHRD_NETROM;
+ nlreq.ifn.rta.rta_len = sizeof(nlreq.ifn);
+ nlreq.ifn.rta.rta_type = IFLA_IFNAME;
+ strlcpy(nlreq.ifn.ifname, req_ifname, sizeof(nlreq.ifn.ifname));
+ nlreq.ifli.rta.rta_len = sizeof(nlreq.ifli);
+ nlreq.ifli.rta.rta_type = IFLA_LINKINFO;
+ nlreq.ifli.ifik.rta.rta_len = sizeof(nlreq.ifli.ifik);
+ nlreq.ifli.ifik.rta.rta_type = IFLA_INFO_KIND;
+ strcpy(nlreq.ifli.ifik.ifkind, "ppp");
+ nlreq.ifli.ifid.rta.rta_len = sizeof(nlreq.ifli.ifid);
+ nlreq.ifli.ifid.rta.rta_type = IFLA_INFO_DATA;
+ nlreq.ifli.ifid.ifdata[0].rta.rta_len = sizeof(nlreq.ifli.ifid.ifdata[0]);
+ nlreq.ifli.ifid.ifdata[0].rta.rta_type = IFLA_PPP_DEV_FD;
+ nlreq.ifli.ifid.ifdata[0].ppp.ppp_dev_fd = ppp_dev_fd;
+
+ /*
+ * See kernel function ppp_nl_newlink(), which may return -EBUSY to prevent
+ * possible deadlock in kernel and ask userspace to retry request again.
+ */
+ do {
+ resp = rtnetlink_msg("RTM_NEWLINK/NLM_F_CREATE", NULL, &nlreq, sizeof(nlreq), NULL, NULL, 0);
+ } while (resp == -EBUSY);
+
+ if (resp) {
+ /*
+ * Linux kernel versions prior to 4.7 do not support creating ppp
+ * interfaces via rtnetlink API and therefore error response is
+ * expected. On older kernel versions do not show this error message.
+ * When error is different than EEXIST then pppd tries to fallback to
+ * the old ioctl method.
+ */
+ errno = (resp < 0) ? -resp : EINVAL;
+ if (kernel_version >= KVERSION(4,7,0))
+ error("Couldn't create ppp interface %s: %m", req_ifname);
+ return 0;
+ }
+
+ return 1;
+}
+
+/*
+ * make_ppp_unit - make a new ppp unit for ppp_dev_fd.
+ * Assumes new_style_driver.
+ */
+static int make_ppp_unit(void)
+{
+ int x, flags;
+
+ if (ppp_dev_fd >= 0) {
+ dbglog("in make_ppp_unit, already had /dev/ppp open?");
+ close(ppp_dev_fd);
+ }
+ ppp_dev_fd = open("/dev/ppp", O_RDWR);
+ if (ppp_dev_fd < 0)
+ fatal("Couldn't open /dev/ppp: %m");
+ flags = fcntl(ppp_dev_fd, F_GETFL);
+ if (flags == -1
+ || fcntl(ppp_dev_fd, F_SETFL, flags | O_NONBLOCK) == -1)
+ warn("Couldn't set /dev/ppp to nonblock: %m");
+
+ /*
+ * Via rtnetlink it is possible to create ppp network interface with
+ * custom ifname atomically. But it is not possible to specify custom
+ * ppp unit id.
+ *
+ * Tools like systemd, udev or NetworkManager are trying to query
+ * interface attributes based on interface name immediately when new
+ * network interface is created. And therefore immediate interface
+ * renaming is causing issues.
+ *
+ * So use rtnetlink API only when user requested custom ifname. It will
+ * avoid system issues with interface renaming.
+ */
+ if (req_unit == -1 && req_ifname[0] != '\0' && kernel_version >= KVERSION(2,1,16)) {
+ if (make_ppp_unit_rtnetlink()) {
+ if (ioctl(ppp_dev_fd, PPPIOCGUNIT, &ifunit))
+ fatal("Couldn't retrieve PPP unit id: %m");
+ return 0;
+ }
+ /*
+ * If interface with requested name already exist return error
+ * otherwise fallback to old ioctl method.
+ */
+ if (errno == EEXIST)
+ return -1;
+ }
+
+ ifunit = req_unit;
+ x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+ if (x < 0 && req_unit >= 0 && errno == EEXIST) {
+ warn("Couldn't allocate PPP unit %d as it is already in use", req_unit);
+ ifunit = -1;
+ x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+ }
+ if (x < 0 && errno == EEXIST) {
+ srand(time(NULL) * getpid());
+ ifunit = rand() % 10000;
+ x = ioctl(ppp_dev_fd, PPPIOCNEWUNIT, &ifunit);
+ }
+ if (x < 0)
+ error("Couldn't create new ppp unit: %m");
+
+ if (x == 0 && req_ifname[0] != '\0') {
+ struct ifreq ifr;
+ char t[IFNAMSIZ];
+ memset(&ifr, 0, sizeof(struct ifreq));
+ slprintf(t, sizeof(t), "%s%d", PPP_DRV_NAME, ifunit);
+ strlcpy(ifr.ifr_name, t, IFNAMSIZ);
+ strlcpy(ifr.ifr_newname, req_ifname, IFNAMSIZ);
+ x = ioctl(sock_fd, SIOCSIFNAME, &ifr);
+ if (x < 0)
+ error("Couldn't rename interface %s to %s: %m", t, req_ifname);
+ else
+ info("Renamed interface %s to %s", t, req_ifname);
+ }
+
+ return x;
+}
+
+/*
+ * cfg_bundle - configure the existing bundle.
+ * Used in demand mode.
+ */
+void cfg_bundle(int mrru, int mtru, int rssn, int tssn)
+{
+ if (!new_style_driver)
+ return;
+
+ /* set the mrru, mtu and flags */
+ if (ioctl(ppp_dev_fd, PPPIOCSMRRU, &mrru) < 0)
+ error("Couldn't set MRRU: %m");
+
+ modify_flags(ppp_dev_fd, SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ|SC_MULTILINK,
+ ((rssn? SC_MP_SHORTSEQ: 0) | (tssn? SC_MP_XSHORTSEQ: 0)
+ | (mrru? SC_MULTILINK: 0)));
+
+ /* connect up the channel */
+ if (ioctl(ppp_fd, PPPIOCCONNECT, &ifunit) < 0)
+ fatal("Couldn't attach to PPP unit %d: %m", ifunit);
+ add_fd(ppp_dev_fd);
+}
+
+/*
+ * make_new_bundle - create a new PPP unit (i.e. a bundle)
+ * and connect our channel to it. This should only get called
+ * if `multilink' was set at the time establish_ppp was called.
+ * In demand mode this uses our existing bundle instead of making
+ * a new one.
+ */
+void make_new_bundle(int mrru, int mtru, int rssn, int tssn)
+{
+ if (!new_style_driver)
+ return;
+
+ /* make us a ppp unit */
+ if (make_ppp_unit() < 0)
+ die(1);
+
+ /* set the mrru and flags */
+ cfg_bundle(mrru, mtru, rssn, tssn);
+}
+
+/*
+ * bundle_attach - attach our link to a given PPP unit.
+ * We assume the unit is controlled by another pppd.
+ */
+int bundle_attach(int ifnum)
+{
+ int master_fd;
+
+ if (!new_style_driver)
+ return -1;
+
+ master_fd = open("/dev/ppp", O_RDWR);
+ if (master_fd < 0)
+ fatal("Couldn't open /dev/ppp: %m");
+ if (ioctl(master_fd, PPPIOCATTACH, &ifnum) < 0) {
+ if (errno == ENXIO) {
+ close(master_fd);
+ return 0; /* doesn't still exist */
+ }
+ fatal("Couldn't attach to interface unit %d: %m\n", ifnum);
+ }
+ if (ioctl(ppp_fd, PPPIOCCONNECT, &ifnum) < 0)
+ fatal("Couldn't connect to interface unit %d: %m", ifnum);
+ modify_flags(master_fd, 0, SC_MULTILINK);
+ close(master_fd);
+
+ ifunit = ifnum;
+ return 1;
+}
+
+/*
+ * destroy_bundle - tell the driver to destroy our bundle.
+ */
+void destroy_bundle(void)
+{
+ if (ppp_dev_fd >= 0) {
+ close(ppp_dev_fd);
+ remove_fd(ppp_dev_fd);
+ ppp_dev_fd = -1;
+ }