[PATCH v4 iproute2-next] iplink_geneve: Support IFLA_GENEVE_LOCAL and IFLA_GENEVE_LOCAL6.

[Kuniyuki Iwashima <kuniyu@google.com>]

IFLA_GENEVE_LOCAL and IFLA_GENEVE_LOCAL6 allow specifying a local
IPv4/IPv6 address for the backend UDP socket of a GENEVE devcie.

Let's support the attributes with the "local" keyword.

  # for i in $(seq 1 2);
  do
          ip link add geneve4_${i} type geneve local 192.168.0.${i} external
          ip addr add 192.168.0.${i}/24 dev geneve4_${i}
          ip link set geneve4_${i} up

          ip link add geneve6_${i} type geneve local 2001:9292::${i} external
          ip addr add 2001:9292::${i}/64 dev geneve6_${i} nodad
          ip link set geneve6_${i} up
  done

  # ip -d l | grep geneve
  9: geneve4_1: <BROADCAST,MULTICAST,UP,LOWER_UP> ...
      geneve external id 0 local 192.168.0.1 ...
  10: geneve6_1: <BROADCAST,MULTICAST,UP,LOWER_UP> ...
      geneve external id 0 local 2001:9292::1 ...
  11: geneve4_2: <BROADCAST,MULTICAST,UP,LOWER_UP> ...
      geneve external id 0 local 192.168.0.2 ...
  12: geneve6_2: <BROADCAST,MULTICAST,UP,LOWER_UP> ...
      geneve external id 0 local 2001:9292::2 ...

  # ss -ua | grep geneve
  UNCONN 0      0         192.168.0.2:geneve      0.0.0.0:*
  UNCONN 0      0         192.168.0.1:geneve      0.0.0.0:*
  UNCONN 0      0      [2001:9292::2]:geneve            *:*
  UNCONN 0      0      [2001:9292::1]:geneve            *:*

Note that kernel dumps the wildcard address if the device created
with IFLA_GENEVE_COLLECT_METADATA is not dualstack.

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
---
The corresponding kernel commit is afabbb56a726 ("geneve: Introduce
IFLA_GENEVE_LOCAL and IFLA_GENEVE_LOCAL6.").

v4:
  * Drop uAPI change
  * Update man

v3:
  * Use strcmp() instead of match()
  * Use print_color_string()

v2: https://lore.kernel.org/netdev/20260602185711.129769-1-kuniyu@google.com/
  * Print LOCAL/LOCAL6 even if wildcard to match the kernel behaviour

v1: https://lore.kernel.org/netdev/20260523061102.2762452-1-kuniyu@google.com/
---
 ip/iplink_geneve.c    | 41 ++++++++++++++++++++++++++++++++++++++++-
 man/man8/ip-link.8.in |  6 ++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/ip/iplink_geneve.c b/ip/iplink_geneve.c
index 62c61bce138b..a096feccbba1 100644
--- a/ip/iplink_geneve.c
+++ b/ip/iplink_geneve.c
@@ -18,6 +18,7 @@ static void print_explain(FILE *f)
 	fprintf(f,
 		"Usage: ... geneve id VNI\n"
 		"		remote ADDR\n"
+		"		[ local ADDR ]\n"
 		"		[ ttl TTL ]\n"
 		"		[ tos TOS ]\n"
 		"		[ df DF ]\n"
@@ -56,7 +57,7 @@ static void check_duparg(__u64 *attrs, int type, const char *key,
 static int geneve_parse_opt(struct link_util *lu, int argc, char **argv,
 			  struct nlmsghdr *n)
 {
-	inet_prefix daddr;
+	inet_prefix daddr, saddr;
 	__u32 vni = 0;
 	__u32 label = 0;
 	__u8 ttl = 0;
@@ -72,6 +73,7 @@ static int geneve_parse_opt(struct link_util *lu, int argc, char **argv,
 	bool inner_proto_inherit = false;
 
 	inet_prefix_reset(&daddr);
+	inet_prefix_reset(&saddr);
 
 	while (argc > 0) {
 		if (!matches(*argv, "id") ||
@@ -88,6 +90,13 @@ static int geneve_parse_opt(struct link_util *lu, int argc, char **argv,
 			get_addr(&daddr, *argv, AF_UNSPEC);
 			if (!is_addrtype_inet_not_multi(&daddr))
 				invarg("invalid remote address", *argv);
+		} else if (!strcmp(*argv, "local")) {
+			NEXT_ARG();
+			check_duparg(&attrs, IFLA_GENEVE_LOCAL, "local",
+				     *argv);
+			get_addr(&saddr, *argv, AF_UNSPEC);
+			if (!is_addrtype_inet_not_multi(&saddr))
+				invarg("invalid local address", *argv);
 		} else if (!matches(*argv, "ttl") ||
 			   !matches(*argv, "hoplimit")) {
 			unsigned int uval;
@@ -221,8 +230,17 @@ static int geneve_parse_opt(struct link_util *lu, int argc, char **argv,
 	if (is_addrtype_inet(&daddr)) {
 		int type = (daddr.family == AF_INET) ? IFLA_GENEVE_REMOTE :
 						       IFLA_GENEVE_REMOTE6;
+
 		addattr_l(n, 1024, type, daddr.data, daddr.bytelen);
 	}
+
+	if (is_addrtype_inet(&saddr)) {
+		int type = (saddr.family == AF_INET) ? IFLA_GENEVE_LOCAL :
+						       IFLA_GENEVE_LOCAL6;
+
+		addattr_l(n, 1024, type, saddr.data, saddr.bytelen);
+	}
+
 	if (!set_op || GENEVE_ATTRSET(attrs, IFLA_GENEVE_LABEL))
 		addattr32(n, 1024, IFLA_GENEVE_LABEL, label);
 	if (!set_op || GENEVE_ATTRSET(attrs, IFLA_GENEVE_TTL))
@@ -285,6 +303,27 @@ static void geneve_print_opt(struct link_util *lu, FILE *f, struct rtattr *tb[])
 		}
 	}
 
+	if (tb[IFLA_GENEVE_LOCAL]) {
+		__be32 addr = rta_getattr_u32(tb[IFLA_GENEVE_LOCAL]);
+
+		print_color_string(PRINT_ANY, COLOR_INET,
+				   "local",
+				   "local %s ",
+				   format_host(AF_INET, 4, &addr));
+	} else if (tb[IFLA_GENEVE_LOCAL6]) {
+		struct in6_addr addr;
+
+		memcpy(&addr, RTA_DATA(tb[IFLA_GENEVE_LOCAL6]), sizeof(struct in6_addr));
+		if (!IN6_IS_ADDR_UNSPECIFIED(&addr)) {
+			print_color_string(PRINT_ANY, COLOR_INET6,
+					   "local6",
+					   "local %s ",
+					   format_host(AF_INET6,
+						       sizeof(struct in6_addr),
+						       &addr));
+		}
+	}
+
 	if (tb[IFLA_GENEVE_TTL_INHERIT] &&
 	    rta_getattr_u8(tb[IFLA_GENEVE_TTL_INHERIT])) {
 		print_string(PRINT_FP, NULL, "ttl %s ", "inherit");
diff --git a/man/man8/ip-link.8.in b/man/man8/ip-link.8.in
index ef45fe08699e..be7d76524724 100644
--- a/man/man8/ip-link.8.in
+++ b/man/man8/ip-link.8.in
@@ -1398,6 +1398,8 @@ the following additional arguments are supported:
 .BI "ip link add " DEVICE
 .BI type " geneve " id " VNI " remote " IPADDR"
 [
+.BI local " IPADDR "
+] [
 .BI ttl " TTL "
 ] [
 .BI tos " TOS "
@@ -1428,6 +1430,10 @@ the following additional arguments are supported:
 .BI remote " IPADDR"
 - specifies the unicast destination IP address to use in outgoing packets.
 
+.sp
+.BI local " IPADDR"
+- specifies the source IP address to listen on.
+
 .sp
 .BI ttl " TTL"
 - specifies the TTL value to use in outgoing packets. "0" or "auto" means
-- 
2.54.0.1032.g2f8565e1d1-goog