Re: [libvirt] [PATCHv3 2/2] Add support for multi-part netlink messages.
On 08/10/2015 01:08 PM, Maxim Perevedentsev wrote:
Such messages do not have NLMSG_ERROR or NLMSG_DONE type
but they are valid responses. We test 'multi-partness'
by looking for NLM_F_MULTI flag.
---
src/util/virnetlink.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/util/virnetlink.c b/src/util/virnetlink.c
index 0052ef9..f02bb59 100644
--- a/src/util/virnetlink.c
+++ b/src/util/virnetlink.c
@@ -386,7 +386,9 @@ virNetlinkGetErrorCode(struct nlmsghdr *resp, unsigned int
recvbuflen)
break;
default:
- goto malformed_resp;
+ /* We allow multipart messages. */
+ if (!(resp->nlmsg_flags & NLM_F_MULTI))
+ goto malformed_resp;
1) It's interesting that they don't seem to define what type the message
will be in these cases (it's not NLMSG_DONE or NLMSG_ERROR, and the only
other standard types are NLMSG_NOOP and NLMSG_OVERRUN.) So what *is* the
type in the case of a multipart message.
2) Doesn't the presence of the NLM_F_MULTI flag indicate that we need to
look for another packet, rather than just returning? It's been a long
time since I looked at the details of the netlink message handling, but
won't this "constipate" the socket?