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plugins: netlink: fix resync request size alignment with kernel

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For RTM_GETLINK we need a `struct ifinfomsg`, not `struct rtmsg`,
otherwise the kernel will get 8 extra bytes and complain about it.

This patch makes sure to set the correct iface change mask as well, and
increases the debug logs a bit to get a fix on sizes used.  We increase
the recv() buffer 8k -> 64k to make sure we can get all data in one big
swoop.  Plan is to refactor this mess in a later commit.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
This commit is contained in:
Joachim Wiberg
2021-05-07 15:20:25 +02:00
parent 910bb13711
commit 6c60b67588
1 changed files with 43 additions and 10 deletions
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plugins/netlink.c
+43 -10
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@@ -32,7 +32,16 @@
#include "plugin.h"
#include "service.h"
#define NL_BUFSZ 8192
/* Used on resync, when we potentially read ALL interfaces in the system */
#define NL_BUFSZ 65536
struct nl_request {
struct nlmsghdr nh;
union {
struct rtmsg rtm;
struct ifinfomsg ifi;
};
};
static int nl_defidx;
static int nl_ifdown;
@@ -262,19 +271,42 @@ static int nl_parse(struct nlmsghdr *nh, ssize_t len)
static int nl_resync_act(int sd, unsigned int seq, int type)
{
struct nlmsghdr *nh;
struct nl_request *nlr = (struct nl_request *)nl_buf;
ssize_t len;
nh = (struct nlmsghdr *)nl_buf;
nh->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
nh->nlmsg_type = type;
nh->nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
nh->nlmsg_seq = seq;
nh->nlmsg_pid = 1;
memset(nlr, 0, sizeof(struct nl_request));
nlr->nh.nlmsg_type = type;
nlr->nh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
nlr->nh.nlmsg_seq = seq;
nlr->nh.nlmsg_pid = 1;
if (send(sd, nh, nh->nlmsg_len, 0) < 0)
switch (type) {
case RTM_GETROUTE:
nlr->rtm.rtm_family = AF_INET;
nlr->rtm.rtm_table = RT_TABLE_MAIN;
nlr->nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
break;
case RTM_GETLINK:
nlr->ifi.ifi_family = AF_UNSPEC;
nlr->ifi.ifi_change = 0xFFFFFFFF;
nlr->nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
break;
default:
_w("Cannot resync, unhandled message type %d", type);
return -1;
}
if (send(sd, nlr, nlr->nh.nlmsg_len, 0) < 0)
return 1;
return nl_parse(nh, recv(sd, nl_buf, NL_BUFSZ, 0));
len = recv(sd, nl_buf, NL_BUFSZ, 0);
if (len < 0)
return -1;
_d("recv %lld bytes in resync path", len);
return nl_parse((struct nlmsghdr *)nl_buf, len);
}
static void nl_resync_routes(int sd, unsigned int seq)
@@ -340,6 +372,7 @@ static void nl_callback(void *arg, int sd, int events)
return;
}
_d("recv %lld bytes in regular path", len);
nl_parse((struct nlmsghdr *)nl_buf, len);
/*