bgpd,lib,sharpd,zebra: srv6 introduce multiple segs/SIDs in nexthop

Append zebra and lib to use muliple SRv6 segs SIDs, and keep one
seg SID for bgpd and sharpd.

Note: bgpd and sharpd compilation relies on the lib and zebra files,
i.e if we separate this: lib or zebra or bgpd or sharpd in different
commits - this will not compile.

Signed-off-by: Dmytro Shytyi <dmytro.shytyi@6wind.com>

bgpd/bgp_zebra.c

@@ -1557,17 +1557,17 @@ void bgp_zebra_announce(struct bgp_dest *dest, const struct prefix *p,
 		api_nh->weight = nh_weight;
 
 		if (((mpinfo->attr->srv6_l3vpn &&
-		      !sid_zero(&mpinfo->attr->srv6_l3vpn->sid)) ||
+		      !sid_zero_ipv6(&mpinfo->attr->srv6_l3vpn->sid)) ||
 		     (mpinfo->attr->srv6_vpn &&
-		      !sid_zero(&mpinfo->attr->srv6_vpn->sid))) &&
+		      !sid_zero_ipv6(&mpinfo->attr->srv6_vpn->sid))) &&
 		    !is_evpn && bgp_is_valid_label(&labels[0])) {
 			struct in6_addr *sid_tmp =
 				mpinfo->attr->srv6_l3vpn
 					? (&mpinfo->attr->srv6_l3vpn->sid)
 					: (&mpinfo->attr->srv6_vpn->sid);
 
-			memcpy(&api_nh->seg6_segs, sid_tmp,
-			       sizeof(api_nh->seg6_segs));
+			memcpy(&api_nh->seg6_segs[0], sid_tmp,
+			       sizeof(api_nh->seg6_segs[0]));
 
 			if (mpinfo->attr->srv6_l3vpn &&
 			    mpinfo->attr->srv6_l3vpn->transposition_len != 0) {
@@ -1581,13 +1581,14 @@ void bgp_zebra_announce(struct bgp_dest *dest, const struct prefix *p,
 					continue;
 				}
 
-				transpose_sid(&api_nh->seg6_segs, nh_label,
+				transpose_sid(&api_nh->seg6_segs[0], nh_label,
 					      mpinfo->attr->srv6_l3vpn
 						      ->transposition_offset,
 					      mpinfo->attr->srv6_l3vpn
 						      ->transposition_len);
 			}
 
+			api_nh->seg_num = 1;
 			SET_FLAG(api_nh->flags, ZAPI_NEXTHOP_FLAG_SEG6);
 		}
 
@@ -1704,7 +1705,7 @@ void bgp_zebra_announce(struct bgp_dest *dest, const struct prefix *p,
 			if (CHECK_FLAG(api_nh->flags, ZAPI_NEXTHOP_FLAG_SEG6) &&
 			    !CHECK_FLAG(api_nh->flags,
 					ZAPI_NEXTHOP_FLAG_EVPN)) {
-				inet_ntop(AF_INET6, &api_nh->seg6_segs,
+				inet_ntop(AF_INET6, &api_nh->seg6_segs[0],
 					  sid_buf, sizeof(sid_buf));
 				snprintf(segs_buf, sizeof(segs_buf), "segs %s",
 					 sid_buf);

include/linux/seg6.h

@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+// SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note
 /*
  *  SR-IPv6 implementation
  *
@@ -30,7 +30,7 @@ struct ipv6_sr_hdr {
 	__u8	flags;
 	__u16	tag;
 
-	struct in6_addr segments[0];
+	struct in6_addr segments[];
 };
 
 #define SR6_FLAG1_PROTECTED	(1 << 6)

lib/nexthop.c

@@ -570,21 +570,38 @@ void nexthop_del_srv6_seg6local(struct nexthop *nexthop)
 
 	nexthop->nh_srv6->seg6local_action = ZEBRA_SEG6_LOCAL_ACTION_UNSPEC;
 
-	if (sid_zero(&nexthop->nh_srv6->seg6_segs))
+	if (nexthop->nh_srv6->seg6_segs == NULL)
 		XFREE(MTYPE_NH_SRV6, nexthop->nh_srv6);
 }
 
-void nexthop_add_srv6_seg6(struct nexthop *nexthop,
-			   const struct in6_addr *segs)
+void nexthop_add_srv6_seg6(struct nexthop *nexthop, const struct in6_addr *segs,
+			   int num_segs)
 {
+	int i;
+
 	if (!segs)
 		return;
 
 	if (!nexthop->nh_srv6)
 		nexthop->nh_srv6 = XCALLOC(MTYPE_NH_SRV6,
 					   sizeof(struct nexthop_srv6));
 
-	nexthop->nh_srv6->seg6_segs = *segs;
+	/* Enforce limit on srv6 seg stack size */
+	if (num_segs > SRV6_MAX_SIDS)
+		num_segs = SRV6_MAX_SIDS;
+
+	if (!nexthop->nh_srv6->seg6_segs) {
+		nexthop->nh_srv6->seg6_segs =
+			XCALLOC(MTYPE_NH_SRV6,
+				sizeof(struct seg6_seg_stack) +
+					num_segs * sizeof(struct in6_addr));
+	}
+
+	nexthop->nh_srv6->seg6_segs->num_segs = num_segs;
+
+	for (i = 0; i < num_segs; i++)
+		memcpy(&nexthop->nh_srv6->seg6_segs->seg[i], &segs[i],
+		       sizeof(struct in6_addr));
 }
 
 void nexthop_del_srv6_seg6(struct nexthop *nexthop)
@@ -810,9 +827,13 @@ void nexthop_copy_no_recurse(struct nexthop *copy,
 			nexthop_add_srv6_seg6local(copy,
 				nexthop->nh_srv6->seg6local_action,
 				&nexthop->nh_srv6->seg6local_ctx);
-		if (!sid_zero(&nexthop->nh_srv6->seg6_segs))
+		if (nexthop->nh_srv6->seg6_segs &&
+		    nexthop->nh_srv6->seg6_segs->num_segs &&
+		    !sid_zero(nexthop->nh_srv6->seg6_segs))
 			nexthop_add_srv6_seg6(copy,
-				&nexthop->nh_srv6->seg6_segs);
+					      &nexthop->nh_srv6->seg6_segs->seg[0],
+					      nexthop->nh_srv6->seg6_segs
+						      ->num_segs);
 	}
 }
 

lib/nexthop.h

@@ -157,8 +157,8 @@ void nexthop_del_labels(struct nexthop *);
 void nexthop_add_srv6_seg6local(struct nexthop *nexthop, uint32_t action,
 				const struct seg6local_context *ctx);
 void nexthop_del_srv6_seg6local(struct nexthop *nexthop);
-void nexthop_add_srv6_seg6(struct nexthop *nexthop,
-			   const struct in6_addr *segs);
+void nexthop_add_srv6_seg6(struct nexthop *nexthop, const struct in6_addr *seg,
+			   int num_segs);
 void nexthop_del_srv6_seg6(struct nexthop *nexthop);
 
 /*

lib/srv6.h

@@ -14,8 +14,11 @@
 #include <arpa/inet.h>
 #include <netinet/in.h>
 
-#define SRV6_MAX_SIDS 16
+#define SRV6_MAX_SIDS	  16
+#define SRV6_MAX_SEGS	  8
 #define SRV6_LOCNAME_SIZE 256
+#define SRH_BASE_HEADER_LENGTH 8
+#define SRH_SEGMENT_LENGTH     16
 
 #ifdef __cplusplus
 extern "C" {
@@ -74,6 +77,8 @@ enum seg6local_flavor_op {
 	ZEBRA_SEG6_LOCAL_FLV_OP_NEXT_CSID    = 4,
 };
 
+#define SRV6_SEG_STRLEN 1024
+
 struct seg6_segs {
 	size_t num_segs;
 	struct in6_addr segs[256];
@@ -89,6 +94,11 @@ struct seg6local_flavors_info {
 	uint8_t lcnode_func_len;
 };
 
+struct seg6_seg_stack {
+	uint8_t num_segs;
+	struct in6_addr seg[0]; /* 1 or more segs */
+};
+
 struct seg6local_context {
 	struct in_addr nh4;
 	struct in6_addr nh6;
@@ -170,7 +180,7 @@ struct nexthop_srv6 {
 	struct seg6local_context seg6local_ctx;
 
 	/* SRv6 Headend-behaviour */
-	struct in6_addr seg6_segs;
+	struct seg6_seg_stack *seg6_segs;
 };
 
 static inline const char *seg6_mode2str(enum seg6_mode_t mode)
@@ -206,12 +216,21 @@ static inline bool sid_diff(
 	return !sid_same(a, b);
 }
 
-static inline bool sid_zero(
-		const struct in6_addr *a)
+
+static inline bool sid_zero(const struct seg6_seg_stack *a)
+{
+	struct in6_addr zero = {};
+
+	assert(a);
+
+	return sid_same(&a->seg[0], &zero);
+}
+
+static inline bool sid_zero_ipv6(const struct in6_addr *a)
 {
 	struct in6_addr zero = {};
 
-	return sid_same(a, &zero);
+	return sid_same(&a[0], &zero);
 }
 
 static inline void *sid_copy(struct in6_addr *dst,

lib/zclient.c

@@ -1061,10 +1061,11 @@ int zapi_nexthop_encode(struct stream *s, const struct zapi_nexthop *api_nh,
 			     sizeof(struct seg6local_context));
 	}
 
-	if (CHECK_FLAG(nh_flags, ZAPI_NEXTHOP_FLAG_SEG6))
-		stream_write(s, &api_nh->seg6_segs,
-			     sizeof(struct in6_addr));
-
+	if (CHECK_FLAG(nh_flags, ZAPI_NEXTHOP_FLAG_SEG6)) {
+		stream_putc(s, api_nh->seg_num);
+		stream_put(s, &api_nh->seg6_segs[0],
+			   api_nh->seg_num * sizeof(struct in6_addr));
+	}
 done:
 	return ret;
 }
@@ -1430,9 +1431,18 @@ int zapi_nexthop_decode(struct stream *s, struct zapi_nexthop *api_nh,
 			   sizeof(struct seg6local_context));
 	}
 
-	if (CHECK_FLAG(api_nh->flags, ZAPI_NEXTHOP_FLAG_SEG6))
-		STREAM_GET(&api_nh->seg6_segs, s,
-			   sizeof(struct in6_addr));
+	if (CHECK_FLAG(api_nh->flags, ZAPI_NEXTHOP_FLAG_SEG6)) {
+		STREAM_GETC(s, api_nh->seg_num);
+		if (api_nh->seg_num > SRV6_MAX_SIDS) {
+			flog_err(EC_LIB_ZAPI_ENCODE,
+				 "%s: invalid number of SRv6 Segs (%u)",
+				 __func__, api_nh->seg_num);
+			return -1;
+		}
+
+		STREAM_GET(&api_nh->seg6_segs[0], s,
+			   api_nh->seg_num * sizeof(struct in6_addr));
+	}
 
 	/* Success */
 	ret = 0;
@@ -2132,8 +2142,8 @@ struct nexthop *nexthop_from_zapi_nexthop(const struct zapi_nexthop *znh)
 		nexthop_add_srv6_seg6local(n, znh->seg6local_action,
 					   &znh->seg6local_ctx);
 
-	if (!sid_zero(&znh->seg6_segs))
-		nexthop_add_srv6_seg6(n, &znh->seg6_segs);
+	if (znh->seg_num && !sid_zero_ipv6(znh->seg6_segs))
+		nexthop_add_srv6_seg6(n, &znh->seg6_segs[0], znh->seg_num);
 
 	return n;
 }
@@ -2193,10 +2203,14 @@ int zapi_nexthop_from_nexthop(struct zapi_nexthop *znh,
 			       sizeof(struct seg6local_context));
 		}
 
-		if (!sid_zero(&nh->nh_srv6->seg6_segs)) {
+		if (nh->nh_srv6->seg6_segs && nh->nh_srv6->seg6_segs->num_segs &&
+		    !sid_zero(nh->nh_srv6->seg6_segs)) {
 			SET_FLAG(znh->flags, ZAPI_NEXTHOP_FLAG_SEG6);
-			memcpy(&znh->seg6_segs, &nh->nh_srv6->seg6_segs,
-			       sizeof(struct in6_addr));
+			znh->seg_num = nh->nh_srv6->seg6_segs->num_segs;
+			for (i = 0; i < nh->nh_srv6->seg6_segs->num_segs; i++)
+				memcpy(&znh->seg6_segs[i],
+				       &nh->nh_srv6->seg6_segs->seg[i],
+				       sizeof(struct in6_addr));
 		}
 	}
 

lib/zclient.h

@@ -438,7 +438,8 @@ struct zapi_nexthop {
 	struct seg6local_context seg6local_ctx;
 
 	/* SRv6 Headend-behaviour */
-	struct in6_addr seg6_segs;
+	int seg_num;
+	struct in6_addr seg6_segs[SRV6_MAX_SEGS];
 };
 
 /*

sharpd/sharp_vty.c

@@ -402,7 +402,7 @@ DEFPY (install_seg6_routes,
 	sg.r.nhop.gate.ipv6 = seg6_nh6;
 	sg.r.nhop.vrf_id = vrf->vrf_id;
 	sg.r.nhop_group.nexthop = &sg.r.nhop;
-	nexthop_add_srv6_seg6(&sg.r.nhop, &seg6_seg);
+	nexthop_add_srv6_seg6(&sg.r.nhop, &seg6_seg, 1);
 
 	sg.r.vrf_id = vrf->vrf_id;
 	sharp_install_routes_helper(&prefix, sg.r.vrf_id, sg.r.inst, 0,