route: Add support for 'seg6 local' encap

Code copied from:
Linux kernel: 6995e2de6891c724bfeb2db33d7b87775f913ad1 (tag: v6.4)
iproute2: 43388c729de3124d30ccd39e1e616ed30a1e2477 (tag: v6.4.0)

Makefile.am

@@ -491,6 +491,8 @@ lib_libnl_route_3_la_SOURCES = \
 	lib/route/nexthop_encap.c \
 	lib/route/nh.c \
 	lib/route/nh_encap_mpls.c \
+	lib/route/nh_encap_seg6.c \
+	lib/route/nh_encap_seg6_local.c \
 	lib/route/nl-route.h \
 	lib/route/pktloc.c \
 	lib/route/qdisc.c \
@@ -514,6 +516,8 @@ lib_libnl_route_3_la_SOURCES = \
 	lib/route/route_utils.c \
 	lib/route/rtnl.c \
 	lib/route/rule.c \
+	lib/route/seg6.c \
+	lib/route/seg6.h \
 	lib/route/tc-api.h \
 	lib/route/tc.c \
 	$(NULL)

include/netlink/route/nexthop.h

@@ -61,11 +61,26 @@ extern int		rtnl_route_nh_str2flags(const char *);
 /*
  * nexthop encapsulations
  */
+extern int		rtnl_route_nh_get_encap_type(struct rtnl_nexthop *nh);
+
 extern int		rtnl_route_nh_encap_mpls(struct rtnl_nexthop *nh,
 						 struct nl_addr *addr,
 						 uint8_t ttl);
 extern struct nl_addr *	rtnl_route_nh_get_encap_mpls_dst(struct rtnl_nexthop *);
 extern uint8_t		rtnl_route_nh_get_encap_mpls_ttl(struct rtnl_nexthop *);
+
+
+extern int		rtnl_route_nh_get_encap_seg6_mode(struct rtnl_nexthop * );
+
+struct ipv6_sr_hdr;
+extern int		rtnl_route_nh_get_encap_seg6_srh(struct rtnl_nexthop *,
+							 const struct ipv6_sr_hdr **);
+
+extern int		rtnl_route_nh_get_encap_seg6_local_action(struct rtnl_nexthop *);
+extern int		rtnl_route_nh_has_encap_seg6_local_attr(struct rtnl_nexthop *, int);
+extern int		rtnl_route_nh_get_encap_seg6_local_table(struct rtnl_nexthop *);
+extern int		rtnl_route_nh_get_encap_seg6_local_vrftable(struct rtnl_nexthop *);
+
 #ifdef __cplusplus
 }
 #endif

lib/route/nexthop-encap.h

@@ -32,4 +32,14 @@ int nh_encap_compare(struct rtnl_nh_encap *a, struct rtnl_nh_encap *b);
  * MPLS encap
  */
 extern struct nh_encap_ops mpls_encap_ops;
+
+/*
+ * SEG6_encap
+ */
+extern struct nh_encap_ops seg6_encap_ops;
+
+/*
+ * SEG6_LOCAL encap
+ */
+extern struct nh_encap_ops seg6_local_encap_ops;
 #endif

lib/route/nexthop.c

@@ -11,6 +11,8 @@
 
 #include "nl-default.h"
 
+#include <linux/lwtunnel.h>
+
 #include <netlink/netlink.h>
 #include <netlink/utils.h>
 #include <netlink/route/rtnl.h>
@@ -412,4 +414,12 @@ int rtnl_route_nh_str2flags(const char *name)
 
 /** @} */
 
+int rtnl_route_nh_get_encap_type(struct rtnl_nexthop *nh)
+{
+	if (nh->rtnh_encap == NULL || nh->rtnh_encap->ops == NULL)
+		return LWTUNNEL_ENCAP_NONE;
+
+	return nh->rtnh_encap->ops->encap_type;
+}
+
 /** @} */

lib/route/nexthop_encap.c

@@ -16,7 +16,10 @@ static struct lwtunnel_encap_type {
 	[LWTUNNEL_ENCAP_IP]   = { .name = "ip" },
 	[LWTUNNEL_ENCAP_IP6]  = { .name = "ip6" },
 	[LWTUNNEL_ENCAP_ILA]  = { .name = "ila" },
+	[LWTUNNEL_ENCAP_SEG6] = { .name = "seg6", .ops = &seg6_encap_ops },
 	[LWTUNNEL_ENCAP_BPF]  = { .name = "bpf" },
+	[LWTUNNEL_ENCAP_SEG6_LOCAL] = { .name = "seg6_local", .ops = &seg6_local_encap_ops },
+
 };
 
 static const char *nh_encap_type2str(unsigned int type)

lib/route/nh_encap_seg6.c

@@ -0,0 +1,167 @@
+/* SPDX-License-Identifier: LGPL-2.1-only */
+
+#include "nl-default.h"
+
+#include <linux/lwtunnel.h>
+#include <linux/seg6_iptunnel.h>
+
+#include <netlink/attr.h>
+#include <netlink/route/nexthop.h>
+
+#include "nl-priv-dynamic-core/nl-core.h"
+#include "nl-route.h"
+#include "nexthop-encap.h"
+#include "seg6.h"
+
+static int seg6_encap_build_msg(struct nl_msg *msg, void *priv)
+{
+	struct seg6_iptunnel_encap *slwt;
+
+	slwt = priv;
+	return nla_put(msg, SEG6_IPTUNNEL_SRH, SEG6_IPTUN_ENCAP_SIZE(slwt),
+		       slwt);
+}
+
+static struct nla_policy seg6_encap_policy[SEG6_IPTUNNEL_MAX + 1] = {
+	[SEG6_IPTUNNEL_SRH] = { .minlen = sizeof(struct seg6_iptunnel_encap) +
+					  sizeof(struct ipv6_sr_hdr) +
+					  sizeof(struct in6_addr) },
+};
+
+/**
+ * Copied from Linux 6.4: seg6_build_state:net/ipv6/seg6_iptunnel.c
+ * Author: David Lebrun <[email protected]>
+ */
+static int seg6_encap_parse_msg(struct nlattr *nla, struct rtnl_nexthop *nh)
+{
+	struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
+	struct seg6_iptunnel_encap *tuninfo;
+	int err, tuninfo_len;
+	struct rtnl_nh_encap *rtnh_encap;
+	struct seg6_iptunnel_encap *slwt;
+
+	err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla, seg6_encap_policy);
+	if (err < 0)
+		return err;
+
+	if (!tb[SEG6_IPTUNNEL_SRH])
+		return -NLE_INVAL;
+
+	tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
+	tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
+
+	switch (tuninfo->mode) {
+	case SEG6_IPTUN_MODE_INLINE:
+		break;
+	case SEG6_IPTUN_MODE_ENCAP:
+		break;
+	case SEG6_IPTUN_MODE_L2ENCAP:
+		break;
+	case SEG6_IPTUN_MODE_ENCAP_RED:
+		break;
+	case SEG6_IPTUN_MODE_L2ENCAP_RED:
+		break;
+	default:
+		return -NLE_INVAL;
+	}
+
+	/* verify that SRH is consistent */
+	if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo)))
+		return -NLE_INVAL;
+
+	slwt = malloc(tuninfo_len);
+	if (slwt == NULL)
+		return -NLE_NOMEM;
+
+	memcpy(slwt, tuninfo, tuninfo_len);
+
+	rtnh_encap = calloc(1, sizeof(*rtnh_encap));
+	if (!rtnh_encap)
+		return -NLE_NOMEM;
+
+	rtnh_encap->priv = slwt;
+	rtnh_encap->ops = &seg6_encap_ops;
+
+	nh_set_encap(nh, rtnh_encap);
+
+	return 0;
+}
+
+static int seg6_encap_compare(void *a, void *b)
+{
+	struct seg6_iptunnel_encap *slwt_a, *slwt_b;
+	int len;
+
+	slwt_a = a;
+	slwt_b = b;
+	len = SEG6_IPTUN_ENCAP_SIZE(slwt_a);
+
+	if (len != SEG6_IPTUN_ENCAP_SIZE(slwt_b))
+		return 1;
+
+	return memcmp(slwt_a, slwt_b, len);
+}
+
+static const char *seg6_mode_types[] = {
+	[SEG6_IPTUN_MODE_INLINE] = "inline",
+	[SEG6_IPTUN_MODE_ENCAP] = "encap",
+	[SEG6_IPTUN_MODE_L2ENCAP] = "l2encap",
+	[SEG6_IPTUN_MODE_ENCAP_RED] = "encap.red",
+	[SEG6_IPTUN_MODE_L2ENCAP_RED] = "l2encap.red"
+};
+
+static void seg6_encap_dump(void *priv, struct nl_dump_params *dp)
+{
+	struct seg6_iptunnel_encap *slwt;
+	const char *mode;
+
+	slwt = priv;
+	if (slwt->mode < 0 || slwt->mode >= ARRAY_SIZE(seg6_mode_types))
+		mode = "<unknown>";
+	else
+		mode = seg6_mode_types[slwt->mode];
+
+	nl_dump(dp, "mode %s ", mode);
+	seg6_dump_srh(dp, slwt->srh);
+}
+
+struct nh_encap_ops seg6_encap_ops = {
+	.encap_type = LWTUNNEL_ENCAP_SEG6,
+	.build_msg = seg6_encap_build_msg,
+	.parse_msg = seg6_encap_parse_msg,
+	.compare = seg6_encap_compare,
+	.dump = seg6_encap_dump,
+};
+
+static struct seg6_iptunnel_encap *get_seg6_slwt(struct rtnl_nexthop *nh)
+{
+	if (!nh->rtnh_encap ||
+	    nh->rtnh_encap->ops->encap_type != LWTUNNEL_ENCAP_SEG6)
+		return NULL;
+
+	return (struct seg6_iptunnel_encap *)nh->rtnh_encap->priv;
+}
+
+int rtnl_route_nh_get_encap_seg6_mode(struct rtnl_nexthop *nh)
+{
+	struct seg6_iptunnel_encap *slwt;
+
+	slwt = get_seg6_slwt(nh);
+	if (slwt == NULL)
+		return -1;
+
+	return slwt->mode;
+}
+
+int rtnl_route_nh_get_encap_seg6_srh(struct rtnl_nexthop *nh,
+				     const struct ipv6_sr_hdr **psrh)
+{
+	struct seg6_iptunnel_encap *slwt;
+
+	slwt = get_seg6_slwt(nh);
+	if (slwt == NULL)
+		return -1;
+
+	*psrh = slwt->srh;
+	return IPV6_EXTHDR_LEN(slwt->srh->hdrlen);
+}