Merge pull request #6616 from pfl/rdnss

networkd: RDNSS option for systemd-networkd prefix delegation

3 files changed, 77 insertions, 4 deletions

diff --git a/src/libsystemd-network/radv-internal.h b/src/libsystemd-network/radv-internal.h
index b21d4e54cb..c3f847ec05 100644
--- a/src/libsystemd-network/radv-internal.h
+++ b/src/libsystemd-network/radv-internal.h
@@ -35,12 +35,21 @@ assert_cc(SD_RADV_DEFAULT_MIN_TIMEOUT_USEC <= SD_RADV_DEFAULT_MAX_TIMEOUT_USEC)
 #define SD_RADV_MIN_DELAY_BETWEEN_RAS           3
 #define SD_RADV_MAX_RA_DELAY_TIME_USEC          (500*USEC_PER_MSEC)
 
+#define SD_RADV_OPT_RDNSS                       25
+
 enum RAdvState {
         SD_RADV_STATE_IDLE                      = 0,
         SD_RADV_STATE_ADVERTISING               = 1,
 };
 typedef enum RAdvState RAdvState;
 
+struct sd_radv_opt_dns {
+        uint8_t type;
+        uint8_t length;
+        uint16_t reserved;
+        be32_t lifetime;
+} _packed_;
+
 struct sd_radv {
         unsigned n_ref;
         RAdvState state;
@@ -63,6 +72,9 @@ struct sd_radv {
 
         unsigned n_prefixes;
         LIST_HEAD(sd_radv_prefix, prefixes);
+
+        size_t n_rdnss;
+        struct sd_radv_opt_dns *rdnss;
 };
 
 struct sd_radv_prefix {
diff --git a/src/libsystemd-network/sd-radv.c b/src/libsystemd-network/sd-radv.c
index f23275a80c..70772b4f15 100644
--- a/src/libsystemd-network/sd-radv.c
+++ b/src/libsystemd-network/sd-radv.c
@@ -126,6 +126,8 @@ _public_ sd_radv *sd_radv_unref(sd_radv *ra) {
                 sd_radv_prefix_unref(p);
         }
 
+        free(ra->rdnss);
+
         radv_reset(ra);
 
         sd_radv_detach_event(ra);
@@ -155,8 +157,8 @@ static int radv_send(sd_radv *ra, const struct in6_addr *dst,
                 .nd_opt_mtu_type = ND_OPT_MTU,
                 .nd_opt_mtu_len = 1,
         };
-        /* Reserve iov space for RA header, linkaddr, MTU + N prefixes */
-        struct iovec iov[3 + ra->n_prefixes];
+        /* Reserve iov space for RA header, linkaddr, MTU, N prefixes, RDNSS */
+        struct iovec iov[4 + ra->n_prefixes];
         struct msghdr msg = {
                 .msg_name = &dst_addr,
                 .msg_namelen = sizeof(dst_addr),
@@ -196,6 +198,12 @@ static int radv_send(sd_radv *ra, const struct in6_addr *dst,
                 msg.msg_iovlen++;
         }
 
+        if (ra->rdnss) {
+                iov[msg.msg_iovlen].iov_base = ra->rdnss;
+                iov[msg.msg_iovlen].iov_len = ra->rdnss->length * 8;
+                msg.msg_iovlen++;
+        }
+
         if (sendmsg(ra->fd, &msg, 0) < 0)
                 return -errno;
 
@@ -546,6 +554,42 @@ _public_ int sd_radv_add_prefix(sd_radv *ra, sd_radv_prefix *p) {
         return 0;
 }
 
+_public_ int sd_radv_set_rdnss(sd_radv *ra, uint32_t lifetime,
+                               const struct in6_addr *dns, size_t n_dns) {
+        _cleanup_free_ struct sd_radv_opt_dns *opt_rdnss = NULL;
+        size_t len;
+
+        assert_return(ra, -EINVAL);
+        assert_return(n_dns < 128, -EINVAL);
+
+        if (!dns || n_dns == 0) {
+                ra->rdnss = mfree(ra->rdnss);
+                ra->n_rdnss = 0;
+
+                return 0;
+        }
+
+        len = sizeof(struct sd_radv_opt_dns) + sizeof(struct in6_addr) * n_dns;
+
+        opt_rdnss = malloc0(len);
+        if (!opt_rdnss)
+                return -ENOMEM;
+
+        opt_rdnss->type = SD_RADV_OPT_RDNSS;
+        opt_rdnss->length = len / 8;
+        opt_rdnss->lifetime = htobe32(lifetime);
+
+        memcpy(opt_rdnss + 1, dns, n_dns * sizeof(struct in6_addr));
+
+        free(ra->rdnss);
+        ra->rdnss = opt_rdnss;
+        opt_rdnss = NULL;
+
+        ra->n_rdnss = n_dns;
+
+        return 0;
+}
+
 _public_ int sd_radv_prefix_new(sd_radv_prefix **ret) {
         _cleanup_(sd_radv_prefix_unrefp) sd_radv_prefix *p = NULL;
 
diff --git a/src/libsystemd-network/test-ndisc-ra.c b/src/libsystemd-network/test-ndisc-ra.c
index 6e6d05642d..eaa49c6a72 100644
--- a/src/libsystemd-network/test-ndisc-ra.c
+++ b/src/libsystemd-network/test-ndisc-ra.c
@@ -53,7 +53,7 @@ static uint8_t advertisement[] = {
         0x00, 0x09, 0x3a, 0x80,  0x00, 0x00, 0x00, 0x00,
         0x20, 0x01, 0x0d, 0xb8,  0xc0, 0x01, 0x0d, 0xad,
         0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00,
-        /* Recursive DNS Server Option - not yet supported */
+        /* Recursive DNS Server Option */
         0x19, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3c,
         0x20, 0x01, 0x0d, 0xb8, 0xde, 0xad, 0xbe, 0xef,
         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
@@ -106,6 +106,11 @@ static struct {
           false },
 };
 
+static const struct in6_addr test_rdnss = { { { 0x20, 0x01, 0x0d, 0xb8,
+                                                0xde, 0xad, 0xbe, 0xef,
+                                                0x00, 0x00, 0x00, 0x00,
+                                                0x00, 0x00, 0x00, 0x01 } } };
+
 static int test_rs_hangcheck(sd_event_source *s, uint64_t usec,
                              void *userdata) {
         assert_se(false);
@@ -207,6 +212,14 @@ static void test_radv(void) {
         assert_se(sd_radv_set_other_information(ra, true) >= 0);
         assert_se(sd_radv_set_other_information(ra, false) >= 0);
 
+        assert_se(sd_radv_set_rdnss(NULL, 0, NULL, 0) < 0);
+        assert_se(sd_radv_set_rdnss(ra, 0, NULL, 0) >= 0);
+        assert_se(sd_radv_set_rdnss(ra, 0, NULL, 128) < 0);
+        assert_se(sd_radv_set_rdnss(ra, 600, &test_rdnss, 0) >= 0);
+        assert_se(sd_radv_set_rdnss(ra, 600, &test_rdnss, 1) >= 0);
+        assert_se(sd_radv_set_rdnss(ra, 0, &test_rdnss, 1) >= 0);
+        assert_se(sd_radv_set_rdnss(ra, 0, NULL, 0) >= 0);
+
         ra = sd_radv_unref(ra);
         assert_se(!ra);
 }
@@ -238,7 +251,7 @@ int icmp6_receive(int fd, void *iov_base, size_t iov_len,
 
 static int radv_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
         sd_radv *ra = userdata;
-        unsigned char buf[120];
+        unsigned char buf[144];
         size_t i;
 
         read(test_fd[0], &buf, sizeof(buf));
@@ -254,6 +267,9 @@ static int radv_recv(sd_event_source *s, int fd, uint32_t revents, void *userdat
 
         /* test only up to buf size, rest is not yet implemented */
         for (i = 0; i < sizeof(buf); i++) {
+                if (!(i % 8))
+                        printf("%3zd: ", i);
+
                 printf("0x%02x", buf[i]);
 
                 assert_se(buf[i] == advertisement[i]);
@@ -302,6 +318,7 @@ static void test_ra(void) {
         assert_se(sd_radv_set_hop_limit(ra, 64) >= 0);
         assert_se(sd_radv_set_managed_information(ra, true) >= 0);
         assert_se(sd_radv_set_other_information(ra, true) >= 0);
+        assert_se(sd_radv_set_rdnss(ra, 60, &test_rdnss, 1) >= 0);
 
         for (i = 0; i < ELEMENTSOF(prefix); i++) {
                 sd_radv_prefix *p;