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Blame SOURCES/0019-iproute-Add-support-for-extended-ack-to-rtnl_talk.patch

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From a9f81b704c4e883a996927e77afdb960a7f47fd9 Mon Sep 17 00:00:00 2001
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From: Hangbin Liu <haliu@redhat.com>
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Date: Wed, 8 Nov 2017 14:39:09 +0800
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Subject: [PATCH] iproute: Add support for extended ack to rtnl_talk
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1380803
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Upstream Status: iproute2.git commit b6432e68ac2f
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Conflicts: Manually added NETLINK_EXT_ACK define to linux headers.
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commit b6432e68ac2f1f6b4ea50aa0d6d47e72c445c71c
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Author: Stephen Hemminger <stephen@networkplumber.org>
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Date:   Fri Aug 4 09:52:15 2017 -0700
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    iproute: Add support for extended ack to rtnl_talk
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    Add support for extended ack error reporting via libmnl.
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    Add a new function rtnl_talk_extack that takes a callback as an input
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    arg. If a netlink response contains extack attributes, the callback is
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    is invoked with the the err string, offset in the message and a pointer
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    to the message returned by the kernel.
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    If iproute2 is built without libmnl, it will still work but
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    extended error reports from kernel will not be available.
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    Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
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Signed-off-by: Hangbin Liu <haliu@redhat.com>
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squash! iproute: Add support for extended ack to rtnl_talk
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---
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 include/libnetlink.h    |   6 +++
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 include/linux/netlink.h |   1 +
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 lib/Makefile            |   7 +++
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 lib/libnetlink.c        | 109 +++++++++++++++++++++++++++++++++++++---
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 4 files changed, 116 insertions(+), 7 deletions(-)
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diff --git a/include/libnetlink.h b/include/libnetlink.h
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index bd0267dfcc02a..654aebc0f7632 100644
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--- a/include/libnetlink.h
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+++ b/include/libnetlink.h
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@@ -65,6 +65,9 @@ typedef int (*rtnl_listen_filter_t)(const struct sockaddr_nl *,
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 				    struct rtnl_ctrl_data *,
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 				    struct nlmsghdr *n, void *);
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+typedef int (*nl_ext_ack_fn_t)(const char *errmsg, uint32_t off,
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+			       const struct nlmsghdr *inner_nlh);
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+
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 struct rtnl_dump_filter_arg {
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 	rtnl_filter_t filter;
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 	void *arg1;
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@@ -81,6 +84,9 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth,
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 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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 	      struct nlmsghdr *answer, size_t len)
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 	__attribute__((warn_unused_result));
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+int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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+	      struct nlmsghdr *answer, size_t len, nl_ext_ack_fn_t errfn)
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+	__attribute__((warn_unused_result));
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 int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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 				   struct nlmsghdr *answer, size_t len)
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 	__attribute__((warn_unused_result));
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diff --git a/include/linux/netlink.h b/include/linux/netlink.h
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index a982b3c004395..d1e26a2bcdcbb 100644
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--- a/include/linux/netlink.h
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+++ b/include/linux/netlink.h
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@@ -113,6 +113,7 @@ struct nlmsgerr {
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 #define NETLINK_LISTEN_ALL_NSID		8
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 #define NETLINK_LIST_MEMBERSHIPS	9
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 #define NETLINK_CAP_ACK			10
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+#define NETLINK_EXT_ACK			11
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 struct nl_pktinfo {
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 	__u32	group;
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diff --git a/lib/Makefile b/lib/Makefile
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index 1d24ca24b9a39..f81888cca974f 100644
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--- a/lib/Makefile
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+++ b/lib/Makefile
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@@ -4,6 +4,13 @@ ifeq ($(IP_CONFIG_SETNS),y)
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 	CFLAGS += -DHAVE_SETNS
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 endif
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+ifeq ($(HAVE_MNL),y)
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+	CFLAGS += $(shell $(PKG_CONFIG) libmnl --cflags)
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+	LDLIBS += $(shell $(PKG_CONFIG) libmnl --libs)
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+else
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+@warn "libmnl required for error support"
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+endif
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+
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 CFLAGS += -fPIC
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 UTILOBJ = utils.o rt_names.o ll_types.o ll_proto.o ll_addr.o \
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diff --git a/lib/libnetlink.c b/lib/libnetlink.c
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index b08518d81f2dd..a0578312e83f8 100644
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--- a/lib/libnetlink.c
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+++ b/lib/libnetlink.c
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@@ -36,6 +36,79 @@
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 int rcvbuf = 1024 * 1024;
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+#ifdef HAVE_LIBMNL
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+#include <libmnl/libmnl.h>
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+
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+static const enum mnl_attr_data_type extack_policy[NLMSGERR_ATTR_MAX + 1] = {
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+	[NLMSGERR_ATTR_MSG]	= MNL_TYPE_NUL_STRING,
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+	[NLMSGERR_ATTR_OFFS]	= MNL_TYPE_U32,
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+};
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+
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+static int err_attr_cb(const struct nlattr *attr, void *data)
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+{
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+	const struct nlattr **tb = data;
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+	uint16_t type;
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+
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+	if (mnl_attr_type_valid(attr, NLMSGERR_ATTR_MAX) < 0)
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+		return MNL_CB_ERROR;
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+
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+	type = mnl_attr_get_type(attr);
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+	if (mnl_attr_validate(attr, extack_policy[type]) < 0)
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+		return MNL_CB_ERROR;
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+
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+
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+	tb[type] = attr;
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+	return MNL_CB_OK;
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+}
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+
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+
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+/* dump netlink extended ack error message */
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+static int nl_dump_ext_err(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
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+{
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+	struct nlattr *tb[NLMSGERR_ATTR_MAX + 1];
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+	const struct nlmsgerr *err = mnl_nlmsg_get_payload(nlh);
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+	const struct nlmsghdr *err_nlh = NULL;
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+	unsigned int hlen = sizeof(*err);
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+	const char *errmsg = NULL;
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+	uint32_t off = 0;
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+
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+	if (!errfn)
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+		return 0;
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+
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+	/* no TLVs, nothing to do here */
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+	if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
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+		return 0;
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+
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+	/* if NLM_F_CAPPED is set then the inner err msg was capped */
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+	if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
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+		hlen += mnl_nlmsg_get_payload_len(&err->msg);
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+
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+	mnl_attr_parse(nlh, hlen, err_attr_cb, tb);
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+
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+	if (tb[NLMSGERR_ATTR_MSG])
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+		errmsg = mnl_attr_get_str(tb[NLMSGERR_ATTR_MSG]);
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+
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+	if (tb[NLMSGERR_ATTR_OFFS]) {
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+		off = mnl_attr_get_u32(tb[NLMSGERR_ATTR_OFFS]);
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+
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+		if (off > nlh->nlmsg_len) {
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+			fprintf(stderr,
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+				"Invalid offset for NLMSGERR_ATTR_OFFS\n");
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+			off = 0;
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+		} else if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
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+			err_nlh = &err->msg;
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+	}
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+
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+	return errfn(errmsg, off, err_nlh);
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+}
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+#else
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+/* No extended error ack without libmnl */
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+static int nl_dump_ext_err(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
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+{
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+	return 0;
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+}
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+#endif
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+
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 void rtnl_close(struct rtnl_handle *rth)
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 {
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 	if (rth->fd >= 0) {
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@@ -49,6 +122,7 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
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 {
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 	socklen_t addr_len;
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 	int sndbuf = 32768;
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+	int one = 1;
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 	memset(rth, 0, sizeof(*rth));
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@@ -71,6 +145,10 @@ int rtnl_open_byproto(struct rtnl_handle *rth, unsigned int subscriptions,
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 		return -1;
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 	}
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+	/* Older kernels may no support extended ACK reporting */
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+	setsockopt(rth->fd, SOL_NETLINK, NETLINK_EXT_ACK,
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+		   &one, sizeof(one));
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+
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 	memset(&rth->local, 0, sizeof(rth->local));
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 	rth->local.nl_family = AF_NETLINK;
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 	rth->local.nl_groups = subscriptions;
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@@ -421,9 +499,19 @@ int rtnl_dump_filter_nc(struct rtnl_handle *rth,
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 	return rtnl_dump_filter_l(rth, a);
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 }
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+static void rtnl_talk_error(struct nlmsghdr *h, struct nlmsgerr *err,
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+			    nl_ext_ack_fn_t errfn)
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+{
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+	if (nl_dump_ext_err(h, errfn))
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+		return;
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+
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+	fprintf(stderr, "RTNETLINK answers: %s\n",
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+		strerror(-err->error));
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+}
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+
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 static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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 		       struct nlmsghdr *answer, size_t maxlen,
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-		       bool show_rtnl_err)
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+		       bool show_rtnl_err, nl_ext_ack_fn_t errfn)
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 {
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 	int status;
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 	unsigned int seq;
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@@ -510,10 +598,10 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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 					return 0;
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 				}
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-				if (rtnl->proto != NETLINK_SOCK_DIAG && show_rtnl_err)
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-					fprintf(stderr,
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-						"RTNETLINK answers: %s\n",
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-						strerror(-err->error));
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+				if (rtnl->proto != NETLINK_SOCK_DIAG &&
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+				    show_rtnl_err)
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+					rtnl_talk_error(h, err, errfn);
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+
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 				errno = -err->error;
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 				return -1;
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 			}
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@@ -545,13 +633,20 @@ static int __rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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 	      struct nlmsghdr *answer, size_t maxlen)
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 {
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-	return __rtnl_talk(rtnl, n, answer, maxlen, true);
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+	return __rtnl_talk(rtnl, n, answer, maxlen, true, NULL);
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+}
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+
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+int rtnl_talk_extack(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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+		     struct nlmsghdr *answer, size_t maxlen,
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+		     nl_ext_ack_fn_t errfn)
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+{
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+	return __rtnl_talk(rtnl, n, answer, maxlen, true, errfn);
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 }
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 int rtnl_talk_suppress_rtnl_errmsg(struct rtnl_handle *rtnl, struct nlmsghdr *n,
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 				   struct nlmsghdr *answer, size_t maxlen)
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 {
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-	return __rtnl_talk(rtnl, n, answer, maxlen, false);
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+	return __rtnl_talk(rtnl, n, answer, maxlen, false, NULL);
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 }
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 int rtnl_listen_all_nsid(struct rtnl_handle *rth)
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-- 
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2.21.0
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