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Message-Id: <1493695105-9418-3-git-send-email-dsa@cumulusnetworks.com>
Date: Mon, 1 May 2017 20:18:24 -0700
From: David Ahern <dsa@...ulusnetworks.com>
To: netdev@...r.kernel.org, stephen@...workplumber.org
Cc: jakub.kicinski@...ronome.com, David Ahern <dsa@...ulusnetworks.com>
Subject: [PATCH net-next iproute2 2/3] netlink: Add support for extended ack to rtnl_talk
Add support for extended ack error reporting.
Add a new function rtnl_talk_extack that takes a callback as an input
arg. If a netlink response contains extack attributes, the callback is
is invoked with the the err string, offset in the message and a pointer
to the message returned by the kernel.
Adding a new function allows commands to be moved over to the
extended error reporting over time.
Signed-off-by: David Ahern <dsa@...ulusnetworks.com>
---
include/libnetlink.h | 6 ++++
lib/libnetlink.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 91 insertions(+), 7 deletions(-)
diff --git a/include/libnetlink.h b/include/libnetlink.h
index e7c46f1870aa..6b031454ce2b 100644
--- a/include/libnetlink.h
+++ b/include/libnetlink.h
@@ -71,6 +71,9 @@ typedef int (*rtnl_listen_filter_t)(const struct sockaddr_nl *,
struct rtnl_ctrl_data *,
struct nlmsghdr *n, void *);
+typedef int (*nl_ext_ack_fn_t)(const char *errmsg, __u32 off,
+ struct nlmsghdr *inner_nlh);
+
struct rtnl_dump_filter_arg {
rtnl_filter_t filter;
void *arg1;
@@ -87,6 +90,9 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth,
int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
struct nlmsghdr *answer, size_t len)
__attribute__((warn_unused_result));
+int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n,
+ struct nlmsghdr *answer, size_t len, nl_ext_ack_fn_t errfn)
+ __attribute__((warn_unused_result));
int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n,
struct nlmsghdr *answer, size_t len)
__attribute__((warn_unused_result));
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index b5ee751c6b86..f6451dec1332 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -32,6 +32,61 @@
int rcvbuf = 1024 * 1024;
+/* dump netlink extended ack error message */
+static int nl_dump_ext_err(struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
+{
+ const struct nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = {
+ [NLMSGERR_ATTR_MSG] = { .type = NLA_STRING },
+ [NLMSGERR_ATTR_OFFS] = { .type = NLA_U32 },
+ };
+ struct nlattr *tb[NLMSGERR_ATTR_MAX + 1], *attr;
+ struct nlmsghdr *err_nlh = NULL;
+ struct nlmsgerr *err;
+ char *errmsg = NULL;
+ int hlen, alen;
+ __u32 off = 0;
+
+ if (!errfn)
+ return 0;
+
+ /* no TLVs, nothing to do here */
+ if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
+ return 0;
+
+ err = (struct nlmsgerr *)NLMSG_DATA(nlh);
+ hlen = sizeof(*err);
+
+ /* if NLM_F_CAPPED is set then the inner err msg was capped */
+ if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
+ hlen += nlmsg_len(&err->msg);
+
+ attr = (struct nlattr *) ((void *) err + hlen);
+ alen = nlh->nlmsg_len - hlen;
+
+ if (nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen, extack_policy) != 0) {
+ fprintf(stderr,
+ "Failed to parse extended error attributes\n");
+ return 0;
+ }
+
+
+ if (tb[NLMSGERR_ATTR_MSG])
+ errmsg = (char *) nla_data(tb[NLMSGERR_ATTR_MSG]);
+
+ if (tb[NLMSGERR_ATTR_OFFS]) {
+ off = nla_get_u32(tb[NLMSGERR_ATTR_OFFS]);
+
+ if (off > nlh->nlmsg_len) {
+ fprintf(stderr,
+ "Invalid offset for NLMSGERR_ATTR_OFFS\n");
+ off = 0;
+ } else if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
+ err_nlh = &err->msg;
+ }
+
+ return errfn(errmsg, off, err_nlh);
+}
+
void rtnl_close(struct rtnl_handle *rth)
{
if (rth->fd >= 0) {
@@ -45,6 +100,7 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
{
socklen_t addr_len;
int sndbuf = 32768;
+ int one = 1;
memset(rth, 0, sizeof(*rth));
@@ -67,6 +123,11 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
return -1;
}
+ if (setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK,
+ &one, sizeof(one)) < 0) {
+ /* debug/verbose message that it is not supported */
+ }
+
memset(&rth->local, 0, sizeof(rth->local));
rth->local.nl_family = AF_NETLINK;
rth->local.nl_groups = subscriptions;
@@ -413,9 +474,19 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth,
return rtnl_dump_filter_l(rth, a);
}
+static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err,
+ nl_ext_ack_fn_t errfn)
+{
+ if (nl_dump_ext_err(h, errfn))
+ return;
+
+ fprintf(stderr, "RTNETLINK answers: %s\n",
+ strerror(-err->error));
+}
+
static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
struct nlmsghdr *answer, size_t maxlen,
- bool show_rtnl_err)
+ bool show_rtnl_err, nl_ext_ack_fn_t errfn)
{
int status;
unsigned int seq;
@@ -502,10 +573,10 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
return 0;
}
- if (rtnl->proto != NETLINK_SOCK_DIAG && show_rtnl_err)
- fprintf(stderr,
- "RTNETLINK answers: %s\n",
- strerror(-err->error));
+ if (rtnl->proto != NETLINK_SOCK_DIAG &&
+ show_rtnl_err)
+ rtnl_talk_error(h, err, errfn);
+
errno = -err->error;
return -1;
}
@@ -537,13 +608,20 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
struct nlmsghdr *answer, size_t maxlen)
{
- return __rtnl_talk(rtnl, n, answer, maxlen, true);
+ return __rtnl_talk(rtnl, n, answer, maxlen, true, NULL);
+}
+
+int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n,
+ struct nlmsghdr *answer, size_t maxlen,
+ nl_ext_ack_fn_t errfn)
+{
+ return __rtnl_talk(rtnl, n, answer, maxlen, true, errfn);
}
int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n,
struct nlmsghdr *answer, size_t maxlen)
{
- return __rtnl_talk(rtnl, n, answer, maxlen, false);
+ return __rtnl_talk(rtnl, n, answer, maxlen, false, NULL);
}
int rtnl_listen_all_nsid(struct rtnl_handle *rth)
--
2.1.4
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