libnetlink: Add test for error code returned from netlink reply
In case if some diag module is not present in the system,
say the kernel is not modern enough, we simply skip the
error code reported. Instead we should check for data
length in NLMSG_DONE and process unsupported case.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 21a7636..a5db168 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -319,6 +319,22 @@
dump_intr = 1;
if (h->nlmsg_type == NLMSG_DONE) {
+ if (rth->proto == NETLINK_SOCK_DIAG) {
+ if (h->nlmsg_len < NLMSG_LENGTH(sizeof(int))) {
+ fprintf(stderr, "DONE truncated\n");
+ return -1;
+ } else {
+ int len = *(int *)NLMSG_DATA(h);
+ if (len < 0) {
+ errno = -len;
+ if (errno == ENOENT ||
+ errno == EOPNOTSUPP)
+ return -1;
+ perror("RTNETLINK answers");
+ return len;
+ }
+ }
+ }
found_done = 1;
break; /* process next filter */
}