hooks: add NOCARRIER_ROAMING reason

This is given when the OS supports the concept of wireless roaming
or the IP setup can be persisted when the carrier drops.

When this happens, routes are moved to a higher metric (if supported)
to support non preferred but non roaming routes.
The `interface_order` hook variable will now order the interfaces
according to priority and move roaming interfaces to the back of the
list.
If resolvconf is present then it is called with the -C option
to deprecate DNS and if carrier comes back it is called again with the
-c option to activate it once more.

As part of this change, default route metrics have been changed to
support a larger number of interfaces.
base metric		1000		(was 200)
wireless offset		2000		(was 100)
IPv4LL offset		1000000		(was 10000)
roaming offset		2000000

diff --git a/BUILDING.md b/BUILDING.md
index f672724a6680bd6459e1b0bcd22b5b4bcadc6d3f..8b4e1ceae09262243b51fcc52b40b8f1b697b479 100644 (file)
--- a/BUILDING.md
+++ b/BUILDING.md
@@ -148,3 +148,11 @@ copied to `$(libexecdir)/dhcpcd-hooks` for use.
 The configure program attempts to find hooks for systems you have installed.
 To add more simply
 `./configure -with-hook=ntp.conf`
+
+If using resolvconf, the `20-resolv.conf` hook now requires a version with the
+`-C` and `-c` options to deprecate and activate interfaces to support wireless
+roaming (Linux) or carrier just drops (NetBSD).
+If your resolvconf does not support this then you will see a warning
+about an illegal option when the carrier changes, but things should still work.
+In this instance the DNS information cannot be Deprecated and may not
+be optimal for multi-homed hosts.

diff --git a/hooks/20-resolv.conf b/hooks/20-resolv.conf
index 73d33386cd91cb4ec438e499c64cc0d2b34f1dbd..86f4873d01fa7cdee3763a3b2675b22a20a9bf1b 100644 (file)
--- a/hooks/20-resolv.conf
+++ b/hooks/20-resolv.conf
@@ -10,6 +10,11 @@ resolv_conf_dir="$state_dir/resolv.conf"
 NL="
 "
 : ${resolvconf:=resolvconf}
+if type "$resolvconf" >/dev/null 2>&1; then
+       have_resolvconf=true
+else
+       have_resolvconf=false
+fi
 
 build_resolv_conf()
 {
@@ -164,7 +169,7 @@ add_resolv_conf()
        for x in ${new_domain_name_servers}; do
                conf="${conf}nameserver $x$NL"
        done
-       if type "$resolvconf" >/dev/null 2>&1; then
+       if $have_resolvconf; then
                [ -n "$ifmetric" ] && export IF_METRIC="$ifmetric"
                printf %s "$conf" | "$resolvconf" -a "$ifname"
                return $?
@@ -180,7 +185,7 @@ add_resolv_conf()
 
 remove_resolv_conf()
 {
-       if type "$resolvconf" >/dev/null 2>&1; then
+       if $have_resolvconf; then
                "$resolvconf" -d "$ifname" -f
        else
                if [ -e "$resolv_conf_dir/$ifname" ]; then
@@ -199,7 +204,11 @@ BOUND6|RENEW6|REBIND6|REBOOT6|INFORM6)
 esac
 
 if $if_configured; then
-       if $if_up || [ "$reason" = ROUTERADVERT ]; then
+       if $have_resolvconf && [ "$reason" = NOCARRIER_ROAMING ]; then
+               "$resolvconf" -C "$interface.*"
+       elif $have_resolvconf && [ "$reason" = CARRIER ]; then
+               "$resolvconf" -c "$interface.*"
+       elif $if_up || [ "$reason" = ROUTERADVERT ]; then
                add_resolv_conf
        elif $if_down; then
                remove_resolv_conf

diff --git a/hooks/dhcpcd-run-hooks.8.in b/hooks/dhcpcd-run-hooks.8.in
index 499157679e7a5ff28affca036a913a3e08e60b61..9b5483a4204d2f66871b9f76c1ba26b80bcb441e 100644 (file)
--- a/hooks/dhcpcd-run-hooks.8.in
+++ b/hooks/dhcpcd-run-hooks.8.in
@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd May 24, 2020
+.Dd December 27, 2020
 .Dt DHCPCD-RUN-HOOKS 8
 .Os
 .Sh NAME
@@ -92,6 +92,9 @@ This is generally just a notification and no action need be taken.
 .It Dv NOCARRIER
 dhcpcd lost the carrier.
 The cable may have been unplugged or association to the wireless point lost.
+.It Dv NOCARRIER_ROAMING
+dhcpcd lost the carrier but the interface configuration is persisted.
+The OS has to support wireless roaming or IP Persistance for this to happen.
 .It Dv INFORM | Dv INFORM6
 dhcpcd informed a DHCP server about its address and obtained other
 configuration details.
@@ -147,10 +150,6 @@ will clear the environment variables aside from
 The following variables will then be set, along with any protocol supplied
 ones.
 .Bl -tag -width xnew_delegated_dhcp6_prefix
-.It Ev $chroot
-the directory where
-.Nm dhcpcd
-is chrooted.
 .It Ev $interface
 the name of the interface.
 .It Ev $protocol
@@ -193,12 +192,14 @@ if the
 .Ev interface
 is up, otherwise
 .Dv false .
+This is more than IFF_UP and may not be equal.
 .It Ev $if_down
 .Dv true
 if the
 .Ev interface
 is down, otherwise
 .Dv false .
+This is more than IFF_UP and may not be equal.
 .It Ev $af_waiting
 Address family waiting for, as defined in
 .Xr dhcpcd.conf 5 .

diff --git a/src/dhcpcd.c b/src/dhcpcd.c
index 1d34cdbb0469208ef5a3a2d4e81abda9d04a3e8f..8762576c13cec90a793d4be11937b2eb396f7e2e 100644 (file)
--- a/src/dhcpcd.c
+++ b/src/dhcpcd.c
@@ -700,26 +700,7 @@ dhcpcd_nocarrier_roaming(struct interface *ifp)
 {
 
        loginfox("%s: carrier lost - roaming", ifp->name);
-
-       /*
-        * XXX We should pass something like NOCARRIER_ROAMING
-        * and set if_up=true; ifdown=false; so that the hook scripts
-        * can make a decision to keep or discard the interface information.
-        *
-        * Currently they discard it (no carrier after all) which is
-        * generally fine as new connections won't work and current
-        * connections try to chug along as best as.
-        * dhcpcd has been doing this since NetBSD-7 at least.
-        *
-        * However, for slow roaming this is poor for say web browsing
-        * as new lookups will fail quickly giving a poor user experience.
-        * We should improve this, but the hooks will require some work first
-        * as we need to introduce a mechanism to sort interfaces by
-        * carrier > roaming > nocarrier. Then the hooks know in which
-        * order to apply their data, if at all.
-        * This probably should be a user toggle.
-        */
-       script_runreason(ifp, "NOCARRIER");
+       script_runreason(ifp, "NOCARRIER_ROAMING");
 
 #ifdef ARP
        arp_drop(ifp);

diff --git a/src/if.c b/src/if.c
index deb5280b34149c0ef9ef6ea30e79b344bca20ae1..d3852f3dc68e86f4577a1f1a109553994397fa4e 100644 (file)
--- a/src/if.c
+++ b/src/if.c
@@ -697,12 +697,11 @@ if_discover(struct dhcpcd_ctx *ctx, struct ifaddrs **ifaddrs,
                        ifp->metric = (unsigned int)ifr.ifr_metric;
                if_getssid(ifp);
 #else
-               /* We reserve the 100 range for virtual interfaces, if and when
-                * we can work them out. */
-               ifp->metric = 200 + ifp->index;
+               /* Leave a low portion for user config */
+               ifp->metric = RTMETRIC_BASE + ifp->index;
                if (if_getssid(ifp) != -1) {
                        ifp->wireless = true;
-                       ifp->metric += 100;
+                       ifp->metric += RTMETRIC_WIRELESS;
                }
 #endif
 

diff --git a/src/ipv4ll.c b/src/ipv4ll.c
index 93898109f7abb090968a4aba102ca7ea5b133d16..6f9cd73d5cf82f84d428be7938dce4078e6ef048 100644 (file)
--- a/src/ipv4ll.c
+++ b/src/ipv4ll.c
@@ -137,7 +137,7 @@ ipv4ll_defaultroute(rb_tree_t *routes, struct interface *ifp)
        sa_in_init(&rt->rt_ifa, &state->addr->addr);
        rt->rt_dflags |= RTDF_IPV4LL;
 #ifdef HAVE_ROUTE_METRIC
-       rt->rt_metric += 10000;
+       rt->rt_metric += RTMETRIC_IPV4LL;
 #endif
        return rt_proto_add(routes, rt) ? 1 : 0;
 }

diff --git a/src/route.c b/src/route.c
index 47fd6cf2a33dbc15f215e10912473a6738f0b317..71523c146a86c0d3fbd0801009e6ab21d1a1882d 100644 (file)
--- a/src/route.c
+++ b/src/route.c
@@ -168,6 +168,15 @@ rt_compare_proto(void *context, const void *node1, const void *node2)
        if (c != 0)
                return -c;
 
+       /* Prefer roaming over non roaming if both carriers are down. */
+       if (ifp1->carrier == LINK_DOWN && ifp2->carrier == LINK_DOWN) {
+               bool roam1 = if_roaming(ifp1);
+               bool roam2 = if_roaming(ifp2);
+
+               if (roam1 != roam2)
+                       return roam1 ? 1 : -1;
+       }
+
 #ifdef INET
        /* IPv4LL routes always come last */
        if (rt1->rt_dflags & RTDF_IPV4LL && !(rt2->rt_dflags & RTDF_IPV4LL))
@@ -374,6 +383,8 @@ rt_setif(struct rt *rt, struct interface *ifp)
        rt->rt_ifp = ifp;
 #ifdef HAVE_ROUTE_METRIC
        rt->rt_metric = ifp->metric;
+       if (if_roaming(ifp))
+               rt->rt_metric += RTMETRIC_ROAM;
 #endif
 }
 

diff --git a/src/route.h b/src/route.h
index e9ac121af3d27d232ed9c8e3f70c535aee29b6c5..cb935c83bdfd54f17a25bc354b20ff434d88170b 100644 (file)
--- a/src/route.h
+++ b/src/route.h
@@ -93,6 +93,15 @@ struct rt {
 #ifdef HAVE_ROUTE_METRIC
        unsigned int            rt_metric;
 #endif
+/* Maximum interface index is generally USHORT_MAX or 65535.
+ * Add some padding for other stuff and we get offsets for the
+ * below that should work automatically.
+ * This is only an issue if the user defines higher metrics in
+ * their configuration, but then they might wish to override also. */
+#define        RTMETRIC_BASE              1000U
+#define        RTMETRIC_WIRELESS          2000U
+#define        RTMETRIC_IPV4LL         1000000U
+#define        RTMETRIC_ROAM           2000000U
 #ifdef HAVE_ROUTE_PREF
        int                     rt_pref;
 #endif

diff --git a/src/script.c b/src/script.c
index 0260845e6a3e89e20744b9665fca6f2ccc2874f6..bf1e5152b7a888af6d23b941ea15f4d9b7b44361 100644 (file)
--- a/src/script.c
+++ b/src/script.c
@@ -74,6 +74,9 @@ static const char * const if_params[] = {
        NULL
 };
 
+static const char * true_str = "true";
+static const char * false_str = "false";
+
 void
 if_printoptions(void)
 {
@@ -228,6 +231,10 @@ make_env(struct dhcpcd_ctx *ctx, const struct interface *ifp,
        const struct if_options *ifo;
        const struct interface *ifp2;
        int af;
+       bool is_stdin = ifp->name[0] == '\0';
+       const char *if_up, *if_down;
+       rb_tree_t ifaces;
+       struct rt *rt;
 #ifdef INET
        const struct dhcp_state *state;
 #ifdef IPV4LL
@@ -237,7 +244,6 @@ make_env(struct dhcpcd_ctx *ctx, const struct interface *ifp,
 #ifdef DHCP6
        const struct dhcp6_state *d6_state;
 #endif
-       bool is_stdin = ifp->name[0] == '\0';
 
 #ifdef HAVE_OPEN_MEMSTREAM
        if (ctx->script_fp == NULL) {
@@ -276,6 +282,7 @@ make_env(struct dhcpcd_ctx *ctx, const struct interface *ifp,
                if (efprintf(fp, "pid=%d", getpid()) == -1)
                        goto eexit;
        }
+
        if (!is_stdin) {
                if (efprintf(fp, "reason=%s", reason) == -1)
                        goto eexit;
@@ -326,6 +333,7 @@ make_env(struct dhcpcd_ctx *ctx, const struct interface *ifp,
        else if (strcmp(reason, "PREINIT") == 0 ||
            strcmp(reason, "CARRIER") == 0 ||
            strcmp(reason, "NOCARRIER") == 0 ||
+           strcmp(reason, "NOCARRIER_ROAMING") == 0 ||
            strcmp(reason, "UNKNOWN") == 0 ||
            strcmp(reason, "DEPARTED") == 0 ||
            strcmp(reason, "STOPPED") == 0)
@@ -382,34 +390,43 @@ make_env(struct dhcpcd_ctx *ctx, const struct interface *ifp,
        if (ifp->ctx->options & DHCPCD_DUMPLEASE)
                goto dumplease;
 
+       rb_tree_init(&ifaces, &rt_compare_proto_ops);
+       TAILQ_FOREACH(ifp2, ifp->ctx->ifaces, next) {
+               rt = rt_new(UNCONST(ifp2));
+               if (rt == NULL)
+                       goto eexit;
+               if (rb_tree_insert_node(&ifaces, rt) != rt)
+                       goto eexit;
+       }
        if (fprintf(fp, "interface_order=") == -1)
                goto eexit;
-       TAILQ_FOREACH(ifp2, ifp->ctx->ifaces, next) {
-               if (ifp2 != TAILQ_FIRST(ifp->ctx->ifaces)) {
-                       if (fputc(' ', fp) == EOF)
-                               return -1;
-               }
-               if (fprintf(fp, "%s", ifp2->name) == -1)
-                       return -1;
+       RB_TREE_FOREACH(rt, &ifaces) {
+               if (rt != RB_TREE_MIN(&ifaces) &&
+                   fprintf(fp, "%s", " ") == -1)
+                       goto eexit;
+               if (fprintf(fp, "%s", rt->rt_ifp->name) == -1)
+                       goto eexit;
        }
+       rt_headclear(&ifaces, AF_UNSPEC);
        if (fputc('\0', fp) == EOF)
-               return -1;
+               goto eexit;
 
        if (strcmp(reason, "STOPPED") == 0) {
-               if (efprintf(fp, "if_up=false") == -1)
-                       goto eexit;
-               if (efprintf(fp, "if_down=%s",
-                   ifo->options & DHCPCD_RELEASE ? "true" : "false") == -1)
-                       goto eexit;
+               if_up = false_str;
+               if_down = ifo->options & DHCPCD_RELEASE ? true_str : false_str;
        } else if (strcmp(reason, "TEST") == 0 ||
            strcmp(reason, "PREINIT") == 0 ||
            strcmp(reason, "CARRIER") == 0 ||
            strcmp(reason, "UNKNOWN") == 0)
        {
-               if (efprintf(fp, "if_up=false") == -1)
-                       goto eexit;
-               if (efprintf(fp, "if_down=false") == -1)
-                       goto eexit;
+               if_up = false_str;
+               if_down = false_str;
+       } else if (strcmp(reason, "NOCARRIER") == 0) {
+               if_up = false_str;
+               if_down = true_str;
+       } else if (strcmp(reason, "NOCARRIER_ROAMING") == 0) {
+               if_up = true_str;
+               if_down = false_str;
        } else if (1 == 2 /* appease ifdefs */
 #ifdef INET
            || (protocol == PROTO_DHCP && state && state->new)
@@ -426,16 +443,17 @@ make_env(struct dhcpcd_ctx *ctx, const struct interface *ifp,
 #endif
            )
        {
-               if (efprintf(fp, "if_up=true") == -1)
-                       goto eexit;
-               if (efprintf(fp, "if_down=false") == -1)
-                       goto eexit;
+               if_up = true_str;
+               if_down = false_str;
        } else {
-               if (efprintf(fp, "if_up=false") == -1)
-                       goto eexit;
-               if (efprintf(fp, "if_down=true") == -1)
-                       goto eexit;
+               if_up = false_str;
+               if_down = true_str;
        }
+       if (efprintf(fp, "if_up=%s", if_up) == -1)
+               goto eexit;
+       if (efprintf(fp, "if_down=%s", if_down) == -1)
+               goto eexit;
+
        if ((af = dhcpcd_ifafwaiting(ifp)) != AF_MAX) {
                if (efprintf(fp, "if_afwaiting=%d", af) == -1)
                        goto eexit;