From: Jean Thomas <jean.thomas@wifirst.fr>
Date: Tue, 20 May 2025 14:02:48 +0000 (+0200)
Subject: ip: filter by group before printing
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=94b015178b7d649777ee0f5cb139de9320fcc26a;p=thirdparty%2Fiproute2.git

ip: filter by group before printing

Filter the output using the requested group, if necessary.

This avoids to print an empty JSON object for each existing item
not matching the group filter when the --json option is used.

Before:
$ ip --json address list group test
[{},{},{},{},{},{},{},{},{},{},{},{}]

After:
$ ip --json address list group test
[]

Signed-off-by: Jean Thomas <jean.thomas@wifirst.fr>
Signed-off-by: David Ahern <dsahern@kernel.org>
---

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 91d78874..bbe48a47 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -959,12 +959,25 @@ static void print_proto_down(FILE *f, struct rtattr *tb[])
 	}
 }
 
+static int get_rtattr(struct nlmsghdr *n, struct rtattr **tb)
+{
+	int len = n->nlmsg_len;
+	struct ifinfomsg *ifi = NLMSG_DATA(n);
+
+	len -= NLMSG_LENGTH(sizeof(*ifi));
+	if (len < 0)
+		return -1;
+
+	parse_rtattr_flags(tb, IFLA_MAX, IFLA_RTA(ifi), len, NLA_F_NESTED);
+
+	return 0;
+}
+
 int print_linkinfo(struct nlmsghdr *n, void *arg)
 {
 	FILE *fp = (FILE *)arg;
 	struct ifinfomsg *ifi = NLMSG_DATA(n);
 	struct rtattr *tb[IFLA_MAX+1];
-	int len = n->nlmsg_len;
 	const char *name;
 	unsigned int m_flag = 0;
 	SPRINT_BUF(b1);
@@ -973,8 +986,7 @@ int print_linkinfo(struct nlmsghdr *n, void *arg)
 	if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)
 		return 0;
 
-	len -= NLMSG_LENGTH(sizeof(*ifi));
-	if (len < 0)
+	if (get_rtattr(n, tb) < 0)
 		return -1;
 
 	if (filter.ifindex && ifi->ifi_index != filter.ifindex)
@@ -984,8 +996,6 @@ int print_linkinfo(struct nlmsghdr *n, void *arg)
 	if (filter.down && ifi->ifi_flags&IFF_UP)
 		return -1;
 
-	parse_rtattr_flags(tb, IFLA_MAX, IFLA_RTA(ifi), len, NLA_F_NESTED);
-
 	name = get_ifname_rta(ifi->ifi_index, tb[IFLA_IFNAME]);
 	if (!name)
 		return -1;
@@ -2121,6 +2131,28 @@ static int ip_addr_list(struct nlmsg_chain *ainfo)
 	return 0;
 }
 
+static void group_filter(struct nlmsg_chain *linfo)
+{
+	struct nlmsg_list *l, **lp;
+
+	lp = &linfo->head;
+	while ((l = *lp) != NULL) {
+		struct nlmsghdr *n = &l->h;
+		struct rtattr *tb[IFLA_MAX+1];
+
+		if (get_rtattr(n, tb) < 0)
+			return;
+
+		if (tb[IFLA_GROUP]) {
+			if (rta_getattr_u32(tb[IFLA_GROUP]) != filter.group) {
+				*lp = l->next;
+				free(l);
+			} else
+				lp = &l->next;
+		}
+	}
+}
+
 static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 {
 	struct nlmsg_chain linfo = { NULL, NULL};
@@ -2299,6 +2331,9 @@ static int ipaddr_list_flush_or_save(int argc, char **argv, int action)
 		ipaddr_filter(&linfo, ainfo);
 	}
 
+	if (filter.group != -1)
+		group_filter(&linfo);
+
 	for (l = linfo.head; l; l = l->next) {
 		struct nlmsghdr *n = &l->h;
 		struct ifinfomsg *ifi = NLMSG_DATA(n);