[Openvpn-devel,2/2] Add basic support for multipath gateway

Message ID 20210413122006.3960-2-themiron@yandex-team.ru
State Superseded
Delegated to: Antonio Quartulli
Headers show
Series
  • [Openvpn-devel,1/2] Fix IPv4 default gateway with multiple route tables
Related show

Commit Message

Vladislav Grishenko April 13, 2021, 12:20 p.m.
Load balancing setup over multiple upstreams may include multipath
gateway route, which is not not supported by OpenVPN.
Let's add basic support for that for selecting best route for zero
destignation address - use any one of nexthop addresses as a gateway,
weights are not handled.

Setup example:

    ip route add default \
        nexthop via 192.168.1.1 dev eth1 weight 1 \
        nexthop via 192.168.2.1 dev eth2 weight 1

Signed-off-by: Vladislav Grishenko <themiron@yandex-team.ru>
---
 src/openvpn/networking_sitnl.c | 37 ++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

Patch

diff --git a/src/openvpn/networking_sitnl.c b/src/openvpn/networking_sitnl.c
index 56543648..8f084687 100644
--- a/src/openvpn/networking_sitnl.c
+++ b/src/openvpn/networking_sitnl.c
@@ -449,6 +449,11 @@  sitnl_route_save(struct nlmsghdr *n, void *arg)
 
     while (RTA_OK(rta, len))
     {
+#ifdef RTA_MULTIPATH
+        struct rtnexthop *nh;
+        int nhlen;
+#endif
+
         switch (rta->rta_type)
         {
             /* route interface */
@@ -469,6 +474,38 @@  sitnl_route_save(struct nlmsghdr *n, void *arg)
             case RTA_TABLE:
                 table = *(unsigned int *)RTA_DATA(rta);
                 break;
+
+#ifdef RTA_MULTIPATH
+            /* multipath nexthops */
+            case RTA_MULTIPATH:
+                nh = RTA_DATA(rta);
+                nhlen = RTA_PAYLOAD(rta);
+
+                while (RTNH_OK(nh, nhlen))
+                {
+                    struct rtattr *nha = RTNH_DATA(nh);
+                    int nhalen = nh->rtnh_len - sizeof(*nh);
+
+                    /* route interface */
+                    ifindex = nh->rtnh_ifindex;
+
+                    while (RTA_OK(nha, nhalen))
+                    {
+                        switch (nha->rta_type)
+                        {
+                            /* GW for the route */
+                            case RTA_GATEWAY:
+                                memcpy(&res->gw, RTA_DATA(nha), res->addr_size);
+                                break;
+                        }
+
+                        nha = RTA_NEXT(nha, nhalen);
+                    }
+
+                    nh = RTNH_NEXT(nh);
+                }
+                break;
+#endif
         }
 
         rta = RTA_NEXT(rta, len);