[iproute PATCH v2 1/2] libnetlink: add a variant of rtnl_send_check that consumes ACKs

Lorenzo Colitti
2015-12-17T13:22:48Z

The new variant is identical to rtnl_send_check, except it also
consumes the kernel response instead of using MSG_PEEK. This is
useful for callers that send simple commands that never cause a
response but only ACKs, and that expect to receive and deal
with errors without printing them to stderr like rtnl_talk does.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
---
include/libnetlink.h | 2 ++
lib/libnetlink.c | 14 +++++++++++---
2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/include/libnetlink.h b/include/libnetlink.h
index 431189e..a88cb4d 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -75,6 +75,8 @@ int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
__attribute__((warn_unused_result));
int rtnl_send(struct rtnl_handle *rth, const void *buf, int)
__attribute__((warn_unused_result));
+int rtnl_send_check_ack(struct rtnl_handle *rth, const void *buf, int, int)
+ __attribute__((warn_unused_result));
int rtnl_send_check(struct rtnl_handle *rth, const void *buf, int)
__attribute__((warn_unused_result));

diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 1658214..a3ad83a 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -134,18 +134,21 @@ int rtnl_send(struct rtnl_handle *rth, const void *buf, int len)
return send(rth->fd, buf, len, 0);
}

-int rtnl_send_check(struct rtnl_handle *rth, const void *buf, int len)
+int rtnl_send_check_ack(struct rtnl_handle *rth, const void *buf, int len,
+ int ack)
{
struct nlmsghdr *h;
- int status;
+ int status, flags;
char resp[1024];

status = send(rth->fd, buf, len, 0);
if (status < 0)
return status;

+ flags = MSG_DONTWAIT | (ack ? 0 : MSG_PEEK);
+
/* Check for immediate errors */
- status = recv(rth->fd, resp, sizeof(resp), MSG_DONTWAIT|MSG_PEEK);
+ status = recv(rth->fd, resp, sizeof(resp), flags);
if (status < 0) {
if (errno == EAGAIN)
return 0;
@@ -167,6 +170,11 @@ int rtnl_send_check(struct rtnl_handle *rth, const void *buf, int len)
return 0;
}

+inline int rtnl_send_check(struct rtnl_handle *rth, const void *buf, int len)
+{
+ return rtnl_send_check_ack(rth, buf, len, 0);
+}
+
int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
{
struct nlmsghdr nlh;
--
2.6.0.rc2.230.g3dd15c0