ip address: Set device index in dump request

Add a filter function to rtnl_addrdump_req to set device index in the
address dump request if the user is filtering addresses by device. In
addition, add a new ipaddr_link_get to do a single RTM_GETLINK request
instead of a device dump yet still store the data in the linfo list.

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

include/libnetlink.h

@@ -49,7 +49,8 @@ void rtnl_close(struct rtnl_handle *rth);
 
 typedef int (*req_filter_fn_t)(struct nlmsghdr *nlh, int reqlen);
 
-int rtnl_addrdump_req(struct rtnl_handle *rth, int family)
+int rtnl_addrdump_req(struct rtnl_handle *rth, int family,
+		      req_filter_fn_t filter_fn)
 	__attribute__((warn_unused_result));
 int rtnl_addrlbldump_req(struct rtnl_handle *rth, int family)
 	__attribute__((warn_unused_result));

ip/ipaddress.c

@@ -1679,6 +1679,15 @@ static void ipaddr_filter(struct nlmsg_chain *linfo, struct nlmsg_chain *ainfo)
 	}
 }
 
+static int ipaddr_dump_filter(struct nlmsghdr *nlh, int reqlen)
+{
+	struct ifaddrmsg *ifa = NLMSG_DATA(nlh);
+
+	ifa->ifa_index = filter.ifindex;
+
+	return 0;
+}
+
 static int ipaddr_flush(void)
 {
 	int round = 0;
@@ -1689,7 +1698,8 @@ static int ipaddr_flush(void)
 	filter.flushe = sizeof(flushb);
 
 	while ((max_flush_loops == 0) || (round < max_flush_loops)) {
-		if (rtnl_addrdump_req(&rth, filter.family) < 0) {
+		if (rtnl_addrdump_req(&rth, filter.family,
+				      ipaddr_dump_filter) < 0) {
 			perror("Cannot send dump request");
 			exit(1);
 		}
@@ -1762,6 +1772,36 @@ static int iplink_filter_req(struct nlmsghdr *nlh, int reqlen)
 	return 0;
 }
 
+static int ipaddr_link_get(int index, struct nlmsg_chain *linfo)
+{
+	struct iplink_req req = {
+		.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
+		.n.nlmsg_flags = NLM_F_REQUEST,
+		.n.nlmsg_type = RTM_GETLINK,
+		.i.ifi_family = filter.family,
+		.i.ifi_index = index,
+	};
+	__u32 filt_mask = RTEXT_FILTER_VF;
+	struct nlmsghdr *answer;
+
+	if (!show_stats)
+		filt_mask |= RTEXT_FILTER_SKIP_STATS;
+
+	addattr32(&req.n, sizeof(req), IFLA_EXT_MASK, filt_mask);
+
+	if (rtnl_talk(&rth, &req.n, &answer) < 0) {
+		perror("Cannot send link request");
+		return 1;
+	}
+
+	if (store_nlmsg(answer, linfo) < 0) {
+		fprintf(stderr, "Failed to process link information\n");
+		return 1;
+	}
+
+	return 0;
+}
+
 /* fills in linfo with link data and optionally ainfo with address info
  * caller can walk lists as desired and must call free_nlmsg_chain for
  * both when done
@@ -1784,7 +1824,7 @@ int ip_link_list(req_filter_fn_t filter_fn, struct nlmsg_chain *linfo)
 
 static int ip_addr_list(struct nlmsg_chain *ainfo)
 {
-	if (rtnl_addrdump_req(&rth, filter.family) < 0) {
+	if (rtnl_addrdump_req(&rth, filter.family, ipaddr_dump_filter) < 0) {
 		perror("Cannot send dump request");
 		return 1;
 	}
@@ -1908,7 +1948,8 @@ static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 		if (ipadd_save_prep())
 			exit(1);
 
-		if (rtnl_addrdump_req(&rth, preferred_family) < 0) {
+		if (rtnl_addrdump_req(&rth, preferred_family,
+				      ipaddr_dump_filter) < 0) {
 			perror("Cannot send dump request");
 			exit(1);
 		}
@@ -1942,8 +1983,13 @@ static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 		goto out;
 	}
 
-	if (ip_link_list(iplink_filter_req, &linfo) != 0)
-		goto out;
+	if (filter.ifindex) {
+		if (ipaddr_link_get(filter.ifindex, &linfo) != 0)
+			goto out;
+	} else {
+		if (ip_link_list(iplink_filter_req, &linfo) != 0)
+			goto out;
+	}
 
 	if (filter.family != AF_PACKET) {
 		if (filter.oneline)
@@ -1972,8 +2018,7 @@ static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 	fflush(stdout);
 
 out:
-	if (ainfo)
-		free_nlmsg_chain(ainfo);
+	free_nlmsg_chain(ainfo);
 	free_nlmsg_chain(&linfo);
 	delete_json_obj();
 	return 0;

lib/libnetlink.c

@@ -234,11 +234,13 @@ int rtnl_open(struct rtnl_handle *rth, unsigned int subscriptions)
 	return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
 }
 
-int rtnl_addrdump_req(struct rtnl_handle *rth, int family)
+int rtnl_addrdump_req(struct rtnl_handle *rth, int family,
+		      req_filter_fn_t filter_fn)
 {
 	struct {
 		struct nlmsghdr nlh;
 		struct ifaddrmsg ifm;
+		char buf[128];
 	} req = {
 		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)),
 		.nlh.nlmsg_type = RTM_GETADDR,
@@ -247,6 +249,14 @@ int rtnl_addrdump_req(struct rtnl_handle *rth, int family)
 		.ifm.ifa_family = family,
 	};
 
+	if (filter_fn) {
+		int err;
+
+		err = filter_fn(&req.nlh, sizeof(req));
+		if (err)
+			return err;
+	}
+
 	return send(rth->fd, &req, sizeof(req), 0);
 }