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Merge pull request #32741 from yuwata/network-dhcp4-route-to-dns

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network/dhcp4: fix assignment of routes to DNS or NTP servers
This commit is contained in:
Luca Boccassi
2024-05-10 12:40:30 +02:00
committed by GitHub
parent b1975df814 0f3116f039
commit 1df2c9a597
2 changed files with 77 additions and 26 deletions
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52
src/network/networkd-dhcp4.c
View File

@@ -147,12 +147,11 @@ static int dhcp4_find_gateway_for_destination(
Link *link,
const struct in_addr *destination,
uint8_t prefixlength,
bool allow_null,
struct in_addr *ret) {
_cleanup_free_ sd_dhcp_route **routes = NULL;
size_t n_routes = 0;
bool is_classless, reachable;
bool is_classless;
uint8_t max_prefixlen = UINT8_MAX;
struct in_addr gw;
int r;
@@ -165,14 +164,21 @@ static int dhcp4_find_gateway_for_destination(
/* This tries to find the most suitable gateway for an address or address range.
* E.g. if the server provides the default gateway 192.168.0.1 and a classless static route for
* 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
* for 9.9.9.9/32. If 'allow_null' flag is set, and the input address or address range is in the
* assigned network, then the default gateway will be ignored and the null address will be returned
* unless a matching non-default gateway found. */
* for 9.9.9.9/32. If the input address or address range is in the assigned network, then the null
* address will be returned. */
/* First, check with the assigned prefix, and if the destination is in the prefix, set the null
* address for the gateway, and return it unless more suitable static route is found. */
r = dhcp4_prefix_covers(link, destination, prefixlength);
if (r < 0)
return r;
reachable = r > 0;
if (r > 0) {
r = sd_dhcp_lease_get_prefix(link->dhcp_lease, NULL, &max_prefixlen);
if (r < 0)
return r;
gw = (struct in_addr) {};
}
r = dhcp4_get_classless_static_or_static_routes(link, &routes, &n_routes);
if (r < 0 && r != -ENODATA)
@@ -208,25 +214,17 @@ static int dhcp4_find_gateway_for_destination(
max_prefixlen = len;
}
/* Found a suitable gateway in classless static routes or static routes. */
/* The destination is reachable. Note, the gateway address returned here may be NULL. */
if (max_prefixlen != UINT8_MAX) {
if (max_prefixlen == 0 && reachable && allow_null)
/* Do not return the default gateway, if the destination is in the assigned network. */
*ret = (struct in_addr) {};
else
*ret = gw;
return 0;
}
/* When the destination is in the assigned network, return the null address if allowed. */
if (reachable && allow_null) {
*ret = (struct in_addr) {};
*ret = gw;
return 0;
}
/* 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 (!is_classless) {
/* No matching static route is found, and the destination is not in the acquired network,
* falling back to the Router option. */
r = dhcp4_get_router(link, ret);
if (r >= 0)
return 0;
@@ -234,11 +232,7 @@ static int dhcp4_find_gateway_for_destination(
return r;
}
if (!reachable)
return -EHOSTUNREACH; /* Not in the same network, cannot reach the destination. */
assert(!allow_null);
return -ENODATA; /* No matching gateway found. */
return -EHOSTUNREACH; /* Cannot reach the destination. */
}
static int dhcp4_remove_address_and_routes(Link *link, bool only_marked) {
@@ -651,8 +645,8 @@ static int dhcp4_request_semi_static_routes(Link *link) {
assert(rt->family == AF_INET);
r = dhcp4_find_gateway_for_destination(link, &rt->dst.in, rt->dst_prefixlen, /* allow_null = */ false, &gw);
if (IN_SET(r, -EHOSTUNREACH, -ENODATA)) {
r = dhcp4_find_gateway_for_destination(link, &rt->dst.in, rt->dst_prefixlen, &gw);
if (r == -EHOSTUNREACH) {
log_link_debug_errno(link, r, "DHCP: Cannot find suitable gateway for destination %s of semi-static route, ignoring: %m",
IN4_ADDR_PREFIX_TO_STRING(&rt->dst.in, rt->dst_prefixlen));
continue;
@@ -660,6 +654,12 @@ static int dhcp4_request_semi_static_routes(Link *link) {
if (r < 0)
return r;
if (in4_addr_is_null(&gw)) {
log_link_debug(link, "DHCP: Destination %s of semi-static route is in the acquired network, skipping configuration.",
IN4_ADDR_PREFIX_TO_STRING(&rt->dst.in, rt->dst_prefixlen));
continue;
}
r = dhcp4_request_route_to_gateway(link, &gw);
if (r < 0)
return r;
@@ -697,7 +697,7 @@ static int dhcp4_request_routes_to_servers(
if (in4_addr_is_null(dst))
continue;
r = dhcp4_find_gateway_for_destination(link, dst, 32, /* allow_null = */ true, &gw);
r = dhcp4_find_gateway_for_destination(link, dst, 32, &gw);
if (r == -EHOSTUNREACH) {
log_link_debug_errno(link, r, "DHCP: Cannot find suitable gateway for destination %s, ignoring: %m",
IN4_ADDR_PREFIX_TO_STRING(dst, 32));

51
src/test/test-in-addr-util.c
View File

@@ -405,4 +405,55 @@ TEST(in_addr_prefixlen_to_netmask) {
}
}
static void in_addr_prefix_covers_full_one(const char *prefix, const char *address, int expected) {
union in_addr_union p, a;
unsigned char plen, alen;
int family, r;
assert_se(in_addr_prefix_from_string_auto(prefix, &family, &p, &plen) >= 0);
assert_se(in_addr_prefix_from_string(address, family, &a, &alen) >= 0);
r = in_addr_prefix_covers_full(family, &p, plen, &a, alen);
if (r != expected)
log_error("in_addr_prefix_covers_full(%s, %s)=%i (expected=%i)", prefix, address, r, expected);
assert_se(r == expected);
}
TEST(in_addr_prefix_covers_full) {
/* From issue #32715. */
in_addr_prefix_covers_full_one("192.168.235.129/32", "192.168.0.128/32", 0);
in_addr_prefix_covers_full_one("192.168.235.130/32", "192.168.0.128/32", 0);
in_addr_prefix_covers_full_one("169.254.0.0/17", "192.168.0.128/32", 0);
in_addr_prefix_covers_full_one("169.254.128.0/17", "192.168.0.128/32", 0);
in_addr_prefix_covers_full_one("0.0.0.0/1", "192.168.0.128/32", 0);
in_addr_prefix_covers_full_one("128.0.0.0/1", "192.168.0.128/32", 1);
in_addr_prefix_covers_full_one("0.0.0.0/0", "192.168.0.128/32", 1);
for (unsigned i = 0; i <= 32; i++) {
_cleanup_free_ char *prefix = NULL;
assert_se(asprintf(&prefix, "192.168.0.128/%u", i) >= 0);
for (unsigned j = 0; j <= 32; j++) {
_cleanup_free_ char *address = NULL;
assert_se(asprintf(&address, "192.168.0.128/%u", j) >= 0);
in_addr_prefix_covers_full_one(prefix, address, i <= j);
}
}
for (unsigned i = 0; i <= 32; i++) {
_cleanup_free_ char *prefix = NULL;
assert_se(asprintf(&prefix, "192.168.235.129/%u", i) >= 0);
in_addr_prefix_covers_full_one(prefix, "192.168.0.128/32", i <= 16);
}
for (unsigned i = 0; i <= 128; i++) {
_cleanup_free_ char *prefix = NULL;
assert_se(asprintf(&prefix, "dead:beef::/%u", i) >= 0);
in_addr_prefix_covers_full_one(prefix, "dead:0:beef::1/128", i <= 16);
}
}
DEFINE_TEST_MAIN(LOG_DEBUG);