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Date: Tue, 12 Jul 2016 21:37:58 +0800
From: Xin Long <lucien.xin@...il.com>
To: network dev <netdev@...r.kernel.org>, stephen@...workplumber.org,
phil@....cc
Subject: [PATCH iproute2] ip route: restore route entries in correct order
Sometimes we cannot restore route entries, because in kernel
[1] fib_check_nh()
[2] fib_valid_prefsrc()
cause some routes to depend on existence of others while adding.
For example, we saved all the routes, and flushed all tables
[a] default via 192.168.122.1 dev eth0
[b] 192.168.122.0/24 dev eth0 src 192.168.122.21
[c] broadcast 127.0.0.0 dev lo table local src 127.0.0.1
[d] local 127.0.0.0/8 dev lo table local src 127.0.0.1
[e] local 127.0.0.1 dev lo table local src 127.0.0.1
[f] broadcast 127.255.255.255 dev lo table local src 127.0.0.1
[g] broadcast 192.168.122.0 dev eth0 table local src 192.168.122.21
[h] local 192.168.122.21 dev eth0 table local src 192.168.122.21
[i] broadcast 192.168.122.255 dev eth0 table local src 192.168.122.21
Now start to restore them:
If we want to add [a], we have to add [b] first, as [1] and
'via 192.168.122.1' in [a].
If we want to add [b], we have to add [h] first, as [2] and
'src 192.168.122.21' in [b].
So the correct order to restore should be like:
[e][h] -> [b][c][d][f][g][i] -> [a]
This patch fixes it by traversing the file 3 times, it only restores
part of them in each run according to the following conditions, to
make sure every entry can be restored successfully.
1. !gw && (!fib_prefsrc || fib_prefsrc == cfg->fc_dst)
2. !gw && (fib_prefsrc != cfg->fc_dst)
3. gw
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
ip/iproute.c | 47 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 45 insertions(+), 2 deletions(-)
diff --git a/ip/iproute.c b/ip/iproute.c
index 24f6b01..c735000 100644
--- a/ip/iproute.c
+++ b/ip/iproute.c
@@ -1810,12 +1810,42 @@ static int iproute_get(int argc, char **argv)
return 0;
}
+static int rtattr_cmp(struct rtattr *rta1, struct rtattr *rta2)
+{
+ if (!rta1 || !rta2 || rta1->rta_len != rta2->rta_len)
+ return 1;
+
+ return memcmp(RTA_DATA(rta1), RTA_DATA(rta2), RTA_PAYLOAD(rta1));
+}
+
static int restore_handler(const struct sockaddr_nl *nl,
struct rtnl_ctrl_data *ctrl,
struct nlmsghdr *n, void *arg)
{
- int ret;
+ struct rtmsg *r = NLMSG_DATA(n);
+ struct rtattr *tb[RTA_MAX+1];
+ int len = n->nlmsg_len - NLMSG_LENGTH(sizeof(*r));
+ int ret, prio = *(int *)arg;
+
+ parse_rtattr(tb, RTA_MAX, RTM_RTA(r), len);
+ /* Restore routes in correct order:
+ * 0. ones for local addresses,
+ * 1. ones for local networks,
+ * 2. others (remote networks/hosts).
+ */
+ if (!prio && !tb[RTA_GATEWAY] && (!tb[RTA_PREFSRC] ||
+ !rtattr_cmp(tb[RTA_PREFSRC], tb[RTA_DST])))
+ goto restore;
+ else if (prio == 1 && !tb[RTA_GATEWAY] &&
+ rtattr_cmp(tb[RTA_PREFSRC], tb[RTA_DST]))
+ goto restore;
+ else if (prio == 2 && tb[RTA_GATEWAY])
+ goto restore;
+
+ return 0;
+
+restore:
n->nlmsg_flags |= NLM_F_REQUEST | NLM_F_CREATE | NLM_F_ACK;
ll_init_map(&rth);
@@ -1848,10 +1878,23 @@ static int route_dump_check_magic(void)
static int iproute_restore(void)
{
+ int pos, prio;
+
if (route_dump_check_magic())
exit(-1);
- exit(rtnl_from_file(stdin, &restore_handler, NULL));
+ pos = ftell(stdin);
+ for (prio = 0; prio < 3; prio++) {
+ int err;
+
+ err = rtnl_from_file(stdin, &restore_handler, &prio);
+ if (err)
+ exit(err);
+
+ fseek(stdin, pos, SEEK_SET);
+ }
+
+ exit(0);
}
static int show_handler(const struct sockaddr_nl *nl,
--
2.1.0
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