dhcp: handle multiple addresses for "Router" (option 3) in DHCP library

The Router DHCP option may contain a list of one or more
routers ([1]). Extend the API of sd_dhcp_lease to return a
list instead of only the first.

Note that networkd still only uses the first router (if present).
Aside from extending the internal API of the DHCP client, there
is almost no change in behavior. The only visible difference in
behavior is that the "ROUTER" variable in the lease file is now a
list of addresses.

Note how RFC 2132 does not define certain IP addresses as invalid for the
router option. Still, previously sd_dhcp_lease_get_router() would never
return a "0.0.0.0" address. In fact, the previous API could not
differenciate whether no router option was present, whether it
was invalid, or whether its first router was "0.0.0.0". No longer let
the DHCP client library impose additional restrictions that are not
part of RFC. Instead, the caller should handle this. The patch does
that, and networkd only consideres the first router entry if it is not
"0.0.0.0".

[1] https://tools.ietf.org/html/rfc2132#section-3.5

diff --git a/src/libsystemd-network/dhcp-lease-internal.h b/src/libsystemd-network/dhcp-lease-internal.h
index 9d245a90596b73b68560378b12eab5fb7685e0b3..122042ab58c5319324e2f25b33215ae479076c91 100644 (file)
--- a/src/libsystemd-network/dhcp-lease-internal.h
+++ b/src/libsystemd-network/dhcp-lease-internal.h
@@ -41,7 +41,6 @@ struct sd_dhcp_lease {
         /* each 0 if unset */
         be32_t address;
         be32_t server_address;
-        be32_t router;
         be32_t next_server;
 
         bool have_subnet_mask;
@@ -50,6 +49,9 @@ struct sd_dhcp_lease {
         bool have_broadcast;
         be32_t broadcast;
 
+        struct in_addr *router;
+        size_t router_size;
+
         struct in_addr *dns;
         size_t dns_size;
 

diff --git a/src/libsystemd-network/sd-dhcp-lease.c b/src/libsystemd-network/sd-dhcp-lease.c
index 13badbf0bfb1ce642c583642e8287baa5b7fe6e4..406188c5c69ca2a2da9302d34b26ffe253a7247a 100644 (file)
--- a/src/libsystemd-network/sd-dhcp-lease.c
+++ b/src/libsystemd-network/sd-dhcp-lease.c
@@ -151,15 +151,15 @@ int sd_dhcp_lease_get_root_path(sd_dhcp_lease *lease, const char **root_path) {
         return 0;
 }
 
-int sd_dhcp_lease_get_router(sd_dhcp_lease *lease, struct in_addr *addr) {
+int sd_dhcp_lease_get_router(sd_dhcp_lease *lease, const struct in_addr **addr) {
         assert_return(lease, -EINVAL);
         assert_return(addr, -EINVAL);
 
-        if (lease->router == 0)
+        if (lease->router_size <= 0)
                 return -ENODATA;
 
-        addr->s_addr = lease->router;
-        return 0;
+        *addr = lease->router;
+        return (int) lease->router_size;
 }
 
 int sd_dhcp_lease_get_netmask(sd_dhcp_lease *lease, struct in_addr *addr) {
@@ -261,6 +261,7 @@ static sd_dhcp_lease *dhcp_lease_free(sd_dhcp_lease *lease) {
         }
 
         free(lease->root_path);
+        free(lease->router);
         free(lease->timezone);
         free(lease->hostname);
         free(lease->domainname);
@@ -387,7 +388,7 @@ static void filter_bogus_addresses(struct in_addr *addresses, size_t *n) {
         *n = j;
 }
 
-static int lease_parse_in_addrs(const uint8_t *option, size_t len, struct in_addr **ret, size_t *n_ret) {
+static int lease_parse_in_addrs(const uint8_t *option, size_t len, bool filter_bogus, struct in_addr **ret, size_t *n_ret) {
         assert(option);
         assert(ret);
         assert(n_ret);
@@ -408,7 +409,8 @@ static int lease_parse_in_addrs(const uint8_t *option, size_t len, struct in_add
                 if (!addresses)
                         return -ENOMEM;
 
-                filter_bogus_addresses(addresses, &n_addresses);
+                if (filter_bogus)
+                        filter_bogus_addresses(addresses, &n_addresses);
 
                 free(*ret);
                 *ret = addresses;
@@ -554,21 +556,19 @@ int dhcp_lease_parse_options(uint8_t code, uint8_t len, const void *option, void
                 break;
 
         case SD_DHCP_OPTION_ROUTER:
-                if (len >= 4) {
-                        r = lease_parse_be32(option, 4, &lease->router);
-                        if (r < 0)
-                                log_debug_errno(r, "Failed to parse router address, ignoring: %m");
-                }
+                r = lease_parse_in_addrs(option, len, false, &lease->router, &lease->router_size);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to parse router addresses, ignoring: %m");
                 break;
 
         case SD_DHCP_OPTION_DOMAIN_NAME_SERVER:
-                r = lease_parse_in_addrs(option, len, &lease->dns, &lease->dns_size);
+                r = lease_parse_in_addrs(option, len, true, &lease->dns, &lease->dns_size);
                 if (r < 0)
                         log_debug_errno(r, "Failed to parse DNS server, ignoring: %m");
                 break;
 
         case SD_DHCP_OPTION_NTP_SERVER:
-                r = lease_parse_in_addrs(option, len, &lease->ntp, &lease->ntp_size);
+                r = lease_parse_in_addrs(option, len, true, &lease->ntp, &lease->ntp_size);
                 if (r < 0)
                         log_debug_errno(r, "Failed to parse NTP server, ignoring: %m");
                 break;
@@ -820,7 +820,6 @@ int dhcp_lease_new(sd_dhcp_lease **ret) {
         if (!lease)
                 return -ENOMEM;
 
-        lease->router = INADDR_ANY;
         lease->n_ref = 1;
 
         *ret = lease;
@@ -863,9 +862,12 @@ int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file) {
         if (r >= 0)
                 fprintf(f, "NETMASK=%s\n", inet_ntoa(address));
 
-        r = sd_dhcp_lease_get_router(lease, &address);
-        if (r >= 0)
-                fprintf(f, "ROUTER=%s\n", inet_ntoa(address));
+        r = sd_dhcp_lease_get_router(lease, &addresses);
+        if (r > 0) {
+                fputs("ROUTER=", f);
+                serialize_in_addrs(f, addresses, r);
+                fputc('\n', f);
+        }
 
         r = sd_dhcp_lease_get_server_identifier(lease, &address);
         if (r >= 0)
@@ -899,14 +901,14 @@ int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file) {
         if (r > 0) {
                 fputs("DNS=", f);
                 serialize_in_addrs(f, addresses, r);
-                fputs("\n", f);
+                fputc('\n', f);
         }
 
         r = sd_dhcp_lease_get_ntp(lease, &addresses);
         if (r > 0) {
                 fputs("NTP=", f);
                 serialize_in_addrs(f, addresses, r);
-                fputs("\n", f);
+                fputc('\n', f);
         }
 
         r = sd_dhcp_lease_get_domainname(lease, &string);
@@ -917,7 +919,7 @@ int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file) {
         if (r > 0) {
                 fputs("DOMAIN_SEARCH_LIST=", f);
                 fputstrv(f, search_domains, NULL, NULL);
-                fputs("\n", f);
+                fputc('\n', f);
         }
 
         r = sd_dhcp_lease_get_hostname(lease, &string);
@@ -1080,9 +1082,11 @@ int dhcp_lease_load(sd_dhcp_lease **ret, const char *lease_file) {
         }
 
         if (router) {
-                r = inet_pton(AF_INET, router, &lease->router);
-                if (r <= 0)
-                        log_debug("Failed to parse router %s, ignoring.", router);
+                r = deserialize_in_addrs(&lease->router, router);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to deserialize router addresses %s, ignoring: %m", router);
+                else
+                        lease->router_size = r;
         }
 
         if (netmask) {

diff --git a/src/libsystemd-network/test-dhcp-client.c b/src/libsystemd-network/test-dhcp-client.c
index fe6788d91b460ab41f337f8b30918d5d0b3c045a..0431e2c3f568605ed2d3e12e8cdd2d6d154b74a1 100644 (file)
--- a/src/libsystemd-network/test-dhcp-client.c
+++ b/src/libsystemd-network/test-dhcp-client.c
@@ -423,6 +423,7 @@ static void test_addr_acq_acquired(sd_dhcp_client *client, int event,
         sd_event *e = userdata;
         sd_dhcp_lease *lease;
         struct in_addr addr;
+        const struct in_addr *addrs;
 
         assert_se(client);
         assert_se(event == SD_DHCP_CLIENT_EVENT_IP_ACQUIRE);
@@ -438,9 +439,9 @@ static void test_addr_acq_acquired(sd_dhcp_client *client, int event,
         assert_se(memcmp(&addr.s_addr, &test_addr_acq_ack[285],
                       sizeof(addr.s_addr)) == 0);
 
-        assert_se(sd_dhcp_lease_get_router(lease, &addr) >= 0);
-        assert_se(memcmp(&addr.s_addr, &test_addr_acq_ack[308],
-                      sizeof(addr.s_addr)) == 0);
+        assert_se(sd_dhcp_lease_get_router(lease, &addrs) == 1);
+        assert_se(memcmp(&addrs[0].s_addr, &test_addr_acq_ack[308],
+                         sizeof(addrs[0].s_addr)) == 0);
 
         if (verbose)
                 printf("  DHCP address acquired\n");

diff --git a/src/network/networkd-dhcp4.c b/src/network/networkd-dhcp4.c
index ace8b254d1484053ea83b6dfd876721aa3ca7922..4493da4d59062edabcfed3a2d4702f89334e4e4e 100644 (file)
--- a/src/network/networkd-dhcp4.c
+++ b/src/network/networkd-dhcp4.c
@@ -51,7 +51,8 @@ static int route_scope_from_address(const Route *route, const struct in_addr *se
 static int link_set_dhcp_routes(Link *link) {
         _cleanup_free_ sd_dhcp_route **static_routes = NULL;
         bool classless_route = false, static_route = false;
-        struct in_addr gateway, address;
+        const struct in_addr *router;
+        struct in_addr address;
         int r, n, i;
         uint32_t table;
 
@@ -118,18 +119,18 @@ static int link_set_dhcp_routes(Link *link) {
                 link->dhcp4_messages++;
         }
 
-        r = sd_dhcp_lease_get_router(link->dhcp_lease, &gateway);
-        if (r == -ENODATA)
-                log_link_info_errno(link, r, "DHCP: No gateway received from DHCP server: %m");
-        else if (r < 0)
+        r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
+        if (r < 0 && r != -ENODATA)
                 log_link_warning_errno(link, r, "DHCP error: could not get gateway: %m");
+        else if (r <= 0 || in4_addr_is_null(&router[0]))
+                log_link_info_errno(link, r, "DHCP: No gateway received from DHCP server: %m");
 
         /* According to RFC 3442: If the DHCP server returns both a Classless Static Routes option and
            a Router option, the DHCP client MUST ignore the Router option. */
         if (classless_route && static_route)
                 log_link_warning(link, "Classless static routes received from DHCP server: ignoring static-route option and router option");
 
-        if (r >= 0 && !classless_route) {
+        if (r > 0 && !classless_route && !in4_addr_is_null(&router[0])) {
                 _cleanup_(route_freep) Route *route = NULL, *route_gw = NULL;
 
                 r = route_new(&route_gw);
@@ -140,7 +141,7 @@ static int link_set_dhcp_routes(Link *link) {
                  * route for the gw host so that we can route no matter the
                  * netmask or existing kernel route tables. */
                 route_gw->family = AF_INET;
-                route_gw->dst.in = gateway;
+                route_gw->dst.in = router[0];
                 route_gw->dst_prefixlen = 32;
                 route_gw->prefsrc.in = address;
                 route_gw->scope = RT_SCOPE_LINK;
@@ -159,7 +160,7 @@ static int link_set_dhcp_routes(Link *link) {
                         return log_link_error_errno(link, r, "Could not allocate route: %m");
 
                 route->family = AF_INET;
-                route->gw.in = gateway;
+                route->gw.in = router[0];
                 route->prefsrc.in = address;
                 route->protocol = RTPROT_DHCP;
                 route->priority = link->network->dhcp_route_metric;
@@ -180,9 +181,9 @@ static int link_set_dhcp_routes(Link *link) {
 
 static int dhcp_lease_lost(Link *link) {
         _cleanup_(address_freep) Address *address = NULL;
+        const struct in_addr *router;
         struct in_addr addr;
         struct in_addr netmask;
-        struct in_addr gateway;
         unsigned prefixlen = 0;
         int r;
 
@@ -215,15 +216,15 @@ static int dhcp_lease_lost(Link *link) {
 
         r = address_new(&address);
         if (r >= 0) {
-                r = sd_dhcp_lease_get_router(link->dhcp_lease, &gateway);
-                if (r >= 0) {
+                r = sd_dhcp_lease_get_router(link->dhcp_lease, &router);
+                if (r > 0 && !in4_addr_is_null(&router[0])) {
                         _cleanup_(route_freep) Route *route_gw = NULL;
                         _cleanup_(route_freep) Route *route = NULL;
 
                         r = route_new(&route_gw);
                         if (r >= 0) {
                                 route_gw->family = AF_INET;
-                                route_gw->dst.in = gateway;
+                                route_gw->dst.in = router[0];
                                 route_gw->dst_prefixlen = 32;
                                 route_gw->scope = RT_SCOPE_LINK;
 
@@ -233,7 +234,7 @@ static int dhcp_lease_lost(Link *link) {
                         r = route_new(&route);
                         if (r >= 0) {
                                 route->family = AF_INET;
-                                route->gw.in = gateway;
+                                route->gw.in = router[0];
 
                                 route_remove(route, link, NULL);
                         }
@@ -392,10 +393,10 @@ static int dhcp_lease_renew(sd_dhcp_client *client, Link *link) {
 }
 
 static int dhcp_lease_acquired(sd_dhcp_client *client, Link *link) {
+        const struct in_addr *router;
         sd_dhcp_lease *lease;
         struct in_addr address;
         struct in_addr netmask;
-        struct in_addr gateway;
         unsigned prefixlen;
         uint32_t lifetime = CACHE_INFO_INFINITY_LIFE_TIME;
         int r;
@@ -417,20 +418,20 @@ static int dhcp_lease_acquired(sd_dhcp_client *client, Link *link) {
 
         prefixlen = in4_addr_netmask_to_prefixlen(&netmask);
 
-        r = sd_dhcp_lease_get_router(lease, &gateway);
+        r = sd_dhcp_lease_get_router(lease, &router);
         if (r < 0 && r != -ENODATA)
                 return log_link_error_errno(link, r, "DHCP error: Could not get gateway: %m");
 
-        if (r >= 0)
+        if (r > 0 && !in4_addr_is_null(&router[0]))
                 log_struct(LOG_INFO,
                            LOG_LINK_INTERFACE(link),
                            LOG_LINK_MESSAGE(link, "DHCPv4 address %u.%u.%u.%u/%u via %u.%u.%u.%u",
                                             ADDRESS_FMT_VAL(address),
                                             prefixlen,
-                                            ADDRESS_FMT_VAL(gateway)),
+                                            ADDRESS_FMT_VAL(router[0])),
                            "ADDRESS=%u.%u.%u.%u", ADDRESS_FMT_VAL(address),
                            "PREFIXLEN=%u", prefixlen,
-                           "GATEWAY=%u.%u.%u.%u", ADDRESS_FMT_VAL(gateway));
+                           "GATEWAY=%u.%u.%u.%u", ADDRESS_FMT_VAL(router[0]));
         else
                 log_struct(LOG_INFO,
                            LOG_LINK_INTERFACE(link),

diff --git a/src/systemd/sd-dhcp-lease.h b/src/systemd/sd-dhcp-lease.h
index 4875f10555c717080a64c9c3618d0a268defae9e..d299c7912148137eada440b3bb46fe44fc119f67 100644 (file)
--- a/src/systemd/sd-dhcp-lease.h
+++ b/src/systemd/sd-dhcp-lease.h
@@ -39,7 +39,7 @@ int sd_dhcp_lease_get_t1(sd_dhcp_lease *lease, uint32_t *t1);
 int sd_dhcp_lease_get_t2(sd_dhcp_lease *lease, uint32_t *t2);
 int sd_dhcp_lease_get_broadcast(sd_dhcp_lease *lease, struct in_addr *addr);
 int sd_dhcp_lease_get_netmask(sd_dhcp_lease *lease, struct in_addr *addr);
-int sd_dhcp_lease_get_router(sd_dhcp_lease *lease, struct in_addr *addr);
+int sd_dhcp_lease_get_router(sd_dhcp_lease *lease, const struct in_addr **addr);
 int sd_dhcp_lease_get_next_server(sd_dhcp_lease *lease, struct in_addr *addr);
 int sd_dhcp_lease_get_server_identifier(sd_dhcp_lease *lease, struct in_addr *addr);
 int sd_dhcp_lease_get_dns(sd_dhcp_lease *lease, const struct in_addr **addr);