From 61ccf0f453306e727e254e6de1641bb934a3b7ec Mon Sep 17 00:00:00 2001
From: Hangbin Liu <haliu@redhat.com>
Date: Wed, 8 Nov 2017 14:39:07 +0800
Subject: [PATCH] netlink: Change rtnl_dump_done to always show error

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1380803
Upstream Status: iproute2.git commit 05a14fc12188

commit 05a14fc1218885ba6236b409fbf6b89976b8636e
Author: David Ahern <dsahern@gmail.com>
Date:   Tue May 16 14:22:46 2017 -0700

    netlink: Change rtnl_dump_done to always show error

    The original code which became rtnl_dump_done only shows netlink errors
    if the protocol is NETLINK_SOCK_DIAG, but netlink dumps always appends
    the length which contains any error encountered during the dump. Update
    rtnl_dump_done to always show the error if there is one.

    As an *example* without this patch, dumping a route object that exceeds
    the internal buffer size terminates with no message to the user -- the
    dump just ends because the NLMSG_DONE attribute was received. With this
    patch the user at least gets a message that the dump was aborted.

    $ ip ro ls
    default via 10.0.2.2 dev eth0
    10.0.2.0/24 dev eth0 proto kernel scope link src 10.0.2.15
    10.10.0.0/16 dev veth1 proto kernel scope link src 10.10.0.1
    172.16.1.0/24 dev br0.11 proto kernel scope link src 172.16.1.1
    Error: Buffer too small for object
    Dump terminated

    The point of this patch is to notify the user of a failure versus
    silently exiting on a partial dump. Because the NLMSG_DONE attribute
    was received, the entire dump needs to be restarted to use a larger
    buffer for EMSGSIZE errors. That could be done automatically but it
    has other user impacts (e.g., duplicate output if the dump is
    restarted) and should be the subject of a different patch.

    Signed-off-by: David Ahern <dsahern@gmail.com>

Signed-off-by: Hangbin Liu <haliu@redhat.com>
---
 lib/libnetlink.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 9303b6686e2c8..e91bd5a02b956 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -266,21 +266,27 @@ static int rtnl_dump_done(const struct rtnl_handle *rth,
 {
 	int len = *(int *)NLMSG_DATA(h);
 
-	if (rth->proto == NETLINK_SOCK_DIAG) {
-		if (h->nlmsg_len < NLMSG_LENGTH(sizeof(int))) {
-			fprintf(stderr, "DONE truncated\n");
-			return -1;
-		}
-
+	if (h->nlmsg_len < NLMSG_LENGTH(sizeof(int))) {
+		fprintf(stderr, "DONE truncated\n");
+		return -1;
+	}
 
-		if (len < 0) {
-			errno = -len;
-			if (errno == ENOENT || errno == EOPNOTSUPP)
-				return -1;
+	if (len < 0) {
+		errno = -len;
+		switch (errno) {
+		case ENOENT:
+		case EOPNOTSUPP:
+			return -1;
+		case EMSGSIZE:
+			fprintf(stderr,
+				"Error: Buffer too small for object.\n");
+			break;
+		default:
 			perror("RTNETLINK answers");
-			return len;
 		}
+		return len;
 	}
+
 	return 0;
 }
 
-- 
2.21.0