sd-dhcp6-client: bind to link-local address

This ensures that several DHCPv6 clients can run on separate interfaces
simultaneously.

3 files changed, 27 insertions, 11 deletions

diff --git a/src/libsystemd-network/dhcp6-network.c b/src/libsystemd-network/dhcp6-network.c
index ec601cbc6a..fd2d60c9d5 100644
--- a/src/libsystemd-network/dhcp6-network.c
+++ b/src/libsystemd-network/dhcp6-network.c
@@ -33,28 +33,23 @@
 #include "socket-util.h"
 
 int dhcp6_network_bind_udp_socket(int index, struct in6_addr *local_address) {
-        struct in6_pktinfo pktinfo = {
-                .ipi6_ifindex = index,
-        };
         union sockaddr_union src = {
                 .in6.sin6_family = AF_INET6,
                 .in6.sin6_port = htobe16(DHCP6_PORT_CLIENT),
-                .in6.sin6_addr = IN6ADDR_ANY_INIT,
+                .in6.sin6_scope_id = index,
         };
         _cleanup_close_ int s = -1;
         int r, off = 0, on = 1;
 
-        if (local_address)
-                src.in6.sin6_addr = *local_address;
+        assert(index > 0);
+        assert(local_address);
+
+        src.in6.sin6_addr = *local_address;
 
         s = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, IPPROTO_UDP);
         if (s < 0)
                 return -errno;
 
-        r = setsockopt(s, IPPROTO_IPV6, IPV6_PKTINFO, &pktinfo, sizeof(pktinfo));
-        if (r < 0)
-                return -errno;
-
         r = setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on));
         if (r < 0)
                 return -errno;
diff --git a/src/libsystemd-network/sd-dhcp6-client.c b/src/libsystemd-network/sd-dhcp6-client.c
index a9518791b3..801331d270 100644
--- a/src/libsystemd-network/sd-dhcp6-client.c
+++ b/src/libsystemd-network/sd-dhcp6-client.c
@@ -32,6 +32,7 @@
 #include "dhcp6-lease-internal.h"
 #include "dhcp6-protocol.h"
 #include "fd-util.h"
+#include "in-addr-util.h"
 #include "network-internal.h"
 #include "random-util.h"
 #include "string-table.h"
@@ -46,6 +47,7 @@ struct sd_dhcp6_client {
         sd_event *event;
         int event_priority;
         int index;
+        struct in6_addr local_address;
         uint8_t mac_addr[MAX_MAC_ADDR_LEN];
         size_t mac_addr_len;
         uint16_t arp_type;
@@ -133,6 +135,18 @@ int sd_dhcp6_client_set_index(sd_dhcp6_client *client, int interface_index) {
         return 0;
 }
 
+int sd_dhcp6_client_set_local_address(sd_dhcp6_client *client, const struct in6_addr *local_address) {
+        assert_return(client, -EINVAL);
+        assert_return(local_address, -EINVAL);
+        assert_return(in_addr_is_link_local(AF_INET6, (const union in_addr_union *) local_address) > 0, -EINVAL);
+
+        assert_return(IN_SET(client->state, DHCP6_STATE_STOPPED), -EBUSY);
+
+        client->local_address = *local_address;
+
+        return 0;
+}
+
 int sd_dhcp6_client_set_mac(
                 sd_dhcp6_client *client,
                 const uint8_t *addr, size_t addr_len,
@@ -1135,6 +1149,7 @@ int sd_dhcp6_client_start(sd_dhcp6_client *client) {
         assert_return(client, -EINVAL);
         assert_return(client->event, -EINVAL);
         assert_return(client->index > 0, -EINVAL);
+        assert_return(in_addr_is_link_local(AF_INET6, (const union in_addr_union *) &client->local_address) > 0, -EINVAL);
 
         if (!IN_SET(client->state, DHCP6_STATE_STOPPED))
                 return -EBUSY;
@@ -1151,7 +1166,7 @@ int sd_dhcp6_client_start(sd_dhcp6_client *client) {
         if (r < 0)
                 return r;
 
-        r = dhcp6_network_bind_udp_socket(client->index, NULL);
+        r = dhcp6_network_bind_udp_socket(client->index, &client->local_address);
         if (r < 0)
                 return r;
 
diff --git a/src/libsystemd-network/test-dhcp6-client.c b/src/libsystemd-network/test-dhcp6-client.c
index 17ed6d58f3..9e05fde8f6 100644
--- a/src/libsystemd-network/test-dhcp6-client.c
+++ b/src/libsystemd-network/test-dhcp6-client.c
@@ -562,6 +562,7 @@ static void test_client_information_cb(sd_dhcp6_client *client, int event,
         sd_event *e = userdata;
         sd_dhcp6_lease *lease;
         struct in6_addr *addrs;
+        struct in6_addr address = { { { 0xfe, 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01 } } };
         char **domains;
 
         assert_se(e);
@@ -590,6 +591,8 @@ static void test_client_information_cb(sd_dhcp6_client *client, int event,
         assert_se(sd_dhcp6_client_set_callback(client,
                                                test_client_solicit_cb, e) >= 0);
 
+        assert_se(sd_dhcp6_client_set_local_address(client, &address) >= 0);
+
         assert_se(sd_dhcp6_client_start(client) >= 0);
 }
 
@@ -701,6 +704,7 @@ int dhcp6_network_bind_udp_socket(int index, struct in6_addr *local_address) {
 static int test_client_solicit(sd_event *e) {
         sd_dhcp6_client *client;
         usec_t time_now = now(clock_boottime_or_monotonic());
+        struct in6_addr address = { { { 0xfe, 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0x01 } } };
         int val = true;
 
         if (verbose)
@@ -729,6 +733,8 @@ static int test_client_solicit(sd_event *e) {
                                     time_now + 2 * USEC_PER_SEC, 0,
                                     test_hangcheck, NULL) >= 0);
 
+        assert_se(sd_dhcp6_client_set_local_address(client, &address) >= 0);
+
         assert_se(sd_dhcp6_client_start(client) >= 0);
 
         sd_event_loop(e);