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network: dhcp4: set gateway for route to DNS server if it is not in the same network

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Fixes #19077.
This commit is contained in:
Yu Watanabe
2021-04-23 08:49:29 +09:00
parent 7f206276ad
commit afe23f876e
1 changed files with 22 additions and 14 deletions
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src/network/networkd-dhcp4.c
+22 -14
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@@ -322,14 +322,16 @@ static int dhcp_route_configure_auto(
return dhcp_route_configure(route, link);
}
static int link_set_dhcp_static_routes(Link *link) {
static int link_set_dhcp_static_routes(Link *link, struct in_addr *ret_default_gw) {
_cleanup_free_ sd_dhcp_route **static_routes = NULL;
bool classless_route = false, static_route = false;
_cleanup_(route_freep) Route *route = NULL;
struct in_addr default_gw = {};
int n, r;
assert(link);
assert(link->dhcp_lease);
assert(ret_default_gw);
if (!link->network->dhcp_use_routes)
return 0;
@@ -388,15 +390,24 @@ static int link_set_dhcp_static_routes(Link *link) {
if (r < 0)
return r;
/* When classless static routes are provided, then router option will be ignored. To
* use the default gateway later in other routes, e.g., routes to dns servers, here we
* need to find the default gateway in the classless static routes. */
if (classless_route &&
in4_addr_is_null(&route->dst.in) && route->dst_prefixlen == 0 &&
in4_addr_is_null(&default_gw))
default_gw = gw;
r = dhcp_route_configure_auto(route, link, &gw);
if (r < 0)
return r;
}
*ret_default_gw = default_gw;
return classless_route;
}
static int link_set_dhcp_gateway(Link *link) {
static int link_set_dhcp_gateway(Link *link, struct in_addr *ret_gw) {
_cleanup_(route_freep) Route *route = NULL;
const struct in_addr *router;
struct in_addr address;
@@ -405,6 +416,7 @@ static int link_set_dhcp_gateway(Link *link) {
assert(link);
assert(link->dhcp_lease);
assert(ret_gw);
if (!link->network->dhcp_use_gateway)
return 0;
@@ -471,18 +483,19 @@ static int link_set_dhcp_gateway(Link *link) {
return r;
}
*ret_gw = router[0];
return 0;
}
static int link_set_dns_routes(Link *link) {
static int link_set_dns_routes(Link *link, const struct in_addr *gw) {
_cleanup_(route_freep) Route *route = NULL;
const struct in_addr *dns;
struct in_addr address;
int n, r;
assert(link);
assert(link->dhcp_lease);
assert(link->network);
assert(gw);
if (!link->network->dhcp_use_dns ||
!link->network->dhcp_routes_to_dns)
@@ -494,18 +507,12 @@ static int link_set_dns_routes(Link *link) {
if (n < 0)
return n;
r = sd_dhcp_lease_get_address(link->dhcp_lease, &address);
if (r < 0)
return r;
r = route_new(&route);
if (r < 0)
return r;
route->family = AF_INET;
route->dst_prefixlen = 32;
route->prefsrc.in = address;
route->scope = RT_SCOPE_LINK;
route->protocol = RTPROT_DHCP;
route->priority = link->network->dhcp_route_metric;
route->table = link_get_dhcp_route_table(link);
@@ -514,7 +521,7 @@ static int link_set_dns_routes(Link *link) {
for (int i = 0; i < n; i ++) {
route->dst.in = dns[i];
r = dhcp_route_configure(route, link);
r = dhcp_route_configure_auto(route, link, gw);
if (r < 0)
return r;
}
@@ -523,6 +530,7 @@ static int link_set_dns_routes(Link *link) {
}
static int link_set_dhcp_routes(Link *link) {
struct in_addr gw = {};
Route *rt;
int r;
@@ -549,18 +557,18 @@ static int link_set_dhcp_routes(Link *link) {
if (r < 0)
return log_link_error_errno(link, r, "DHCP error: Could not set prefix route: %m");
r = link_set_dhcp_static_routes(link);
r = link_set_dhcp_static_routes(link, &gw);
if (r < 0)
return log_link_error_errno(link, r, "DHCP error: Could not set static routes: %m");
if (r == 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. */
r = link_set_dhcp_gateway(link);
r = link_set_dhcp_gateway(link, &gw);
if (r < 0)
return log_link_error_errno(link, r, "DHCP error: Could not set gateway: %m");
}
r = link_set_dns_routes(link);
r = link_set_dns_routes(link, &gw);
if (r < 0)
return log_link_error_errno(link, r, "DHCP error: Could not set routes to DNS servers: %m");