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Merge pull request #32741 from yuwata/network-dhcp4-route-to-dns
network/dhcp4: fix assignment of routes to DNS or NTP servers
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commit
1df2c9a597
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@ -147,12 +147,11 @@ static int dhcp4_find_gateway_for_destination(
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Link *link,
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const struct in_addr *destination,
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uint8_t prefixlength,
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bool allow_null,
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struct in_addr *ret) {
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_cleanup_free_ sd_dhcp_route **routes = NULL;
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size_t n_routes = 0;
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bool is_classless, reachable;
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bool is_classless;
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uint8_t max_prefixlen = UINT8_MAX;
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struct in_addr gw;
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int r;
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@ -165,14 +164,21 @@ static int dhcp4_find_gateway_for_destination(
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/* This tries to find the most suitable gateway for an address or address range.
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* E.g. if the server provides the default gateway 192.168.0.1 and a classless static route for
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* 8.0.0.0/8 with gateway 192.168.0.2, then this returns 192.168.0.2 for 8.8.8.8/32, and 192.168.0.1
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* for 9.9.9.9/32. If 'allow_null' flag is set, and the input address or address range is in the
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* assigned network, then the default gateway will be ignored and the null address will be returned
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* unless a matching non-default gateway found. */
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* for 9.9.9.9/32. If the input address or address range is in the assigned network, then the null
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* address will be returned. */
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/* First, check with the assigned prefix, and if the destination is in the prefix, set the null
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* address for the gateway, and return it unless more suitable static route is found. */
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r = dhcp4_prefix_covers(link, destination, prefixlength);
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if (r < 0)
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return r;
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reachable = r > 0;
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if (r > 0) {
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r = sd_dhcp_lease_get_prefix(link->dhcp_lease, NULL, &max_prefixlen);
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if (r < 0)
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return r;
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gw = (struct in_addr) {};
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}
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r = dhcp4_get_classless_static_or_static_routes(link, &routes, &n_routes);
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if (r < 0 && r != -ENODATA)
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@ -208,25 +214,17 @@ static int dhcp4_find_gateway_for_destination(
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max_prefixlen = len;
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}
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/* Found a suitable gateway in classless static routes or static routes. */
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/* The destination is reachable. Note, the gateway address returned here may be NULL. */
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if (max_prefixlen != UINT8_MAX) {
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if (max_prefixlen == 0 && reachable && allow_null)
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/* Do not return the default gateway, if the destination is in the assigned network. */
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*ret = (struct in_addr) {};
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else
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*ret = gw;
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return 0;
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}
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/* When the destination is in the assigned network, return the null address if allowed. */
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if (reachable && allow_null) {
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*ret = (struct in_addr) {};
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*ret = gw;
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return 0;
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}
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/* According to RFC 3442: If the DHCP server returns both a Classless Static Routes option and
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* a Router option, the DHCP client MUST ignore the Router option. */
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if (!is_classless) {
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/* No matching static route is found, and the destination is not in the acquired network,
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* falling back to the Router option. */
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r = dhcp4_get_router(link, ret);
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if (r >= 0)
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return 0;
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@ -234,11 +232,7 @@ static int dhcp4_find_gateway_for_destination(
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return r;
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}
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if (!reachable)
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return -EHOSTUNREACH; /* Not in the same network, cannot reach the destination. */
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assert(!allow_null);
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return -ENODATA; /* No matching gateway found. */
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return -EHOSTUNREACH; /* Cannot reach the destination. */
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}
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static int dhcp4_remove_address_and_routes(Link *link, bool only_marked) {
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@ -651,8 +645,8 @@ static int dhcp4_request_semi_static_routes(Link *link) {
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assert(rt->family == AF_INET);
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r = dhcp4_find_gateway_for_destination(link, &rt->dst.in, rt->dst_prefixlen, /* allow_null = */ false, &gw);
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if (IN_SET(r, -EHOSTUNREACH, -ENODATA)) {
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r = dhcp4_find_gateway_for_destination(link, &rt->dst.in, rt->dst_prefixlen, &gw);
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if (r == -EHOSTUNREACH) {
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log_link_debug_errno(link, r, "DHCP: Cannot find suitable gateway for destination %s of semi-static route, ignoring: %m",
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IN4_ADDR_PREFIX_TO_STRING(&rt->dst.in, rt->dst_prefixlen));
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continue;
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@ -660,6 +654,12 @@ static int dhcp4_request_semi_static_routes(Link *link) {
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if (r < 0)
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return r;
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if (in4_addr_is_null(&gw)) {
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log_link_debug(link, "DHCP: Destination %s of semi-static route is in the acquired network, skipping configuration.",
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IN4_ADDR_PREFIX_TO_STRING(&rt->dst.in, rt->dst_prefixlen));
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continue;
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}
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r = dhcp4_request_route_to_gateway(link, &gw);
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if (r < 0)
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return r;
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@ -697,7 +697,7 @@ static int dhcp4_request_routes_to_servers(
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if (in4_addr_is_null(dst))
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continue;
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r = dhcp4_find_gateway_for_destination(link, dst, 32, /* allow_null = */ true, &gw);
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r = dhcp4_find_gateway_for_destination(link, dst, 32, &gw);
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if (r == -EHOSTUNREACH) {
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log_link_debug_errno(link, r, "DHCP: Cannot find suitable gateway for destination %s, ignoring: %m",
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IN4_ADDR_PREFIX_TO_STRING(dst, 32));
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@ -405,4 +405,55 @@ TEST(in_addr_prefixlen_to_netmask) {
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}
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}
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static void in_addr_prefix_covers_full_one(const char *prefix, const char *address, int expected) {
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union in_addr_union p, a;
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unsigned char plen, alen;
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int family, r;
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assert_se(in_addr_prefix_from_string_auto(prefix, &family, &p, &plen) >= 0);
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assert_se(in_addr_prefix_from_string(address, family, &a, &alen) >= 0);
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r = in_addr_prefix_covers_full(family, &p, plen, &a, alen);
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if (r != expected)
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log_error("in_addr_prefix_covers_full(%s, %s)=%i (expected=%i)", prefix, address, r, expected);
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assert_se(r == expected);
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}
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TEST(in_addr_prefix_covers_full) {
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/* From issue #32715. */
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in_addr_prefix_covers_full_one("192.168.235.129/32", "192.168.0.128/32", 0);
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in_addr_prefix_covers_full_one("192.168.235.130/32", "192.168.0.128/32", 0);
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in_addr_prefix_covers_full_one("169.254.0.0/17", "192.168.0.128/32", 0);
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in_addr_prefix_covers_full_one("169.254.128.0/17", "192.168.0.128/32", 0);
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in_addr_prefix_covers_full_one("0.0.0.0/1", "192.168.0.128/32", 0);
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in_addr_prefix_covers_full_one("128.0.0.0/1", "192.168.0.128/32", 1);
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in_addr_prefix_covers_full_one("0.0.0.0/0", "192.168.0.128/32", 1);
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for (unsigned i = 0; i <= 32; i++) {
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_cleanup_free_ char *prefix = NULL;
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assert_se(asprintf(&prefix, "192.168.0.128/%u", i) >= 0);
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for (unsigned j = 0; j <= 32; j++) {
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_cleanup_free_ char *address = NULL;
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assert_se(asprintf(&address, "192.168.0.128/%u", j) >= 0);
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in_addr_prefix_covers_full_one(prefix, address, i <= j);
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}
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}
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for (unsigned i = 0; i <= 32; i++) {
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_cleanup_free_ char *prefix = NULL;
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assert_se(asprintf(&prefix, "192.168.235.129/%u", i) >= 0);
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in_addr_prefix_covers_full_one(prefix, "192.168.0.128/32", i <= 16);
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}
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for (unsigned i = 0; i <= 128; i++) {
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_cleanup_free_ char *prefix = NULL;
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assert_se(asprintf(&prefix, "dead:beef::/%u", i) >= 0);
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in_addr_prefix_covers_full_one(prefix, "dead:0:beef::1/128", i <= 16);
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}
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}
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DEFINE_TEST_MAIN(LOG_DEBUG);
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