isisd: Add Segment Routing Local Block support

Segment Routing Local Block (SRLB) is part of RFC8667. This change introduces
the possibility for isisd to advertize SRLB in LSP. Base and Range of SRLB
could be configured through CLI or Yang.

Adjacency-SID are now using this SRLB for label allocation. SRLB could also
be used for SID-Binding (e.g. LDP to SR).

Signed-off-by: Olivier Dugeon <olivier.dugeon@orange.com>

1 files changed, 81 insertions, 29 deletions

diff --git a/isisd/isis_tlvs.c b/isisd/isis_tlvs.c
index 923956fa6..a58038b32 100644
--- a/isisd/isis_tlvs.c
+++ b/isisd/isis_tlvs.c
@@ -2620,30 +2620,35 @@ static void format_tlv_router_cap(const struct isis_router_cap *router_cap,
 
 	/* Segment Routing Global Block as per RFC8667 section #3.1 */
 	if (router_cap->srgb.range_size != 0)
-		sbuf_push(buf, indent,
-			"  Segment Routing: I:%s V:%s, SRGB Base: %d Range: %d\n",
+		sbuf_push(
+			buf, indent,
+			"  Segment Routing: I:%s V:%s, Global Block Base: %u Range: %u\n",
 			IS_SR_IPV4(router_cap->srgb) ? "1" : "0",
 			IS_SR_IPV6(router_cap->srgb) ? "1" : "0",
 			router_cap->srgb.lower_bound,
 			router_cap->srgb.range_size);
 
+	/* Segment Routing Local Block as per RFC8667 section #3.3 */
+	if (router_cap->srlb.range_size != 0)
+		sbuf_push(buf, indent, "  SR Local Block Base: %u Range: %u\n",
+			  router_cap->srlb.lower_bound,
+			  router_cap->srlb.range_size);
+
 	/* Segment Routing Algorithms as per RFC8667 section #3.2 */
 	if (router_cap->algo[0] != SR_ALGORITHM_UNSET) {
-		sbuf_push(buf, indent, "    Algorithm: %s",
-			  router_cap->algo[0] == 0 ? "0: SPF"
-						   : "0: Strict SPF");
-		for (int i = 1; i < SR_ALGORITHM_COUNT; i++)
+		sbuf_push(buf, indent, "  SR Algorithm:\n");
+		for (int i = 0; i < SR_ALGORITHM_COUNT; i++)
 			if (router_cap->algo[i] != SR_ALGORITHM_UNSET)
-				sbuf_push(buf, indent, " %s",
-					  router_cap->algo[1] == 0
-						  ? "0: SPF"
-						  : "0: Strict SPF");
-		sbuf_push(buf, indent, "\n");
+				sbuf_push(buf, indent, "    %u: %s\n", i,
+					  router_cap->algo[i] == 0
+						  ? "SPF"
+						  : "Strict SPF");
 	}
 
 	/* Segment Routing Node MSD as per RFC8491 section #2 */
 	if (router_cap->msd != 0)
-		sbuf_push(buf, indent, "    Node MSD: %d\n", router_cap->msd);
+		sbuf_push(buf, indent, "  Node Maximum SID Depth: %u\n",
+			  router_cap->msd);
 }
 
 static void free_tlv_router_cap(struct isis_router_cap *router_cap)
@@ -2699,6 +2704,20 @@ static int pack_tlv_router_cap(const struct isis_router_cap *router_cap,
 			for (int i = 0; i < nb_algo; i++)
 				stream_putc(s, router_cap->algo[i]);
 		}
+
+		/* Local Block if defined as per RFC8667 section #3.3 */
+		if ((router_cap->srlb.range_size != 0)
+		    && (router_cap->srlb.lower_bound != 0)) {
+			stream_putc(s, ISIS_SUBTLV_SRLB);
+			stream_putc(s, ISIS_SUBTLV_SID_LABEL_RANGE_SIZE);
+			/* No Flags are defined for SRLB */
+			stream_putc(s, 0);
+			stream_put3(s, router_cap->srlb.range_size);
+			stream_putc(s, ISIS_SUBTLV_SID_LABEL);
+			stream_putc(s, ISIS_SUBTLV_SID_LABEL_SIZE);
+			stream_put3(s, router_cap->srlb.lower_bound);
+		}
+
 		/* And finish with MSD if set as per RFC8491 section #2 */
 		if (router_cap->msd != 0) {
 			stream_putc(s, ISIS_SUBTLV_NODE_MSD);
@@ -2721,6 +2740,7 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
 				       void *dest, int indent)
 {
 	struct isis_tlvs *tlvs = dest;
+	struct isis_router_cap *rcap;
 	uint8_t type;
 	uint8_t length;
 	uint8_t subtlv_len;
@@ -2741,47 +2761,51 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
 	}
 
 	/* Allocate router cap structure and initialize SR Algorithms */
-	tlvs->router_cap = XCALLOC(MTYPE_ISIS_TLV, sizeof(*tlvs->router_cap));
+	rcap = XCALLOC(MTYPE_ISIS_TLV, sizeof(struct isis_router_cap));
 	for (int i = 0; i < SR_ALGORITHM_COUNT; i++)
-		tlvs->router_cap->algo[i] = SR_ALGORITHM_UNSET;
+		rcap->algo[i] = SR_ALGORITHM_UNSET;
 
 	/* Get Router ID and Flags */
-	tlvs->router_cap->router_id.s_addr = stream_get_ipv4(s);
-	tlvs->router_cap->flags = stream_getc(s);
+	rcap->router_id.s_addr = stream_get_ipv4(s);
+	rcap->flags = stream_getc(s);
 
 	/* Parse remaining part of the TLV if present */
 	subtlv_len = tlv_len - ISIS_ROUTER_CAP_SIZE;
 	while (subtlv_len > 2) {
-		struct isis_router_cap *rc = tlvs->router_cap;
 		uint8_t msd_type;
 
 		type = stream_getc(s);
 		length = stream_getc(s);
 		switch (type) {
 		case ISIS_SUBTLV_SID_LABEL_RANGE:
-			rc->srgb.flags = stream_getc(s);
-			rc->srgb.range_size = stream_get3(s);
+			/* Only one SRGB is supported. Skip subsequent one */
+			if (rcap->srgb.range_size != 0) {
+				stream_forward_getp(s, length);
+				continue;
+			}
+			rcap->srgb.flags = stream_getc(s);
+			rcap->srgb.range_size = stream_get3(s);
 			/* Skip Type and get Length of SID Label */
 			stream_getc(s);
 			sid_len = stream_getc(s);
 			if (sid_len == ISIS_SUBTLV_SID_LABEL_SIZE)
-				rc->srgb.lower_bound = stream_get3(s);
+				rcap->srgb.lower_bound = stream_get3(s);
 			else
-				rc->srgb.lower_bound = stream_getl(s);
+				rcap->srgb.lower_bound = stream_getl(s);
 
 			/* SRGB sanity checks. */
-			if (rc->srgb.range_size == 0
-			    || (rc->srgb.lower_bound <= MPLS_LABEL_RESERVED_MAX)
-			    || ((rc->srgb.lower_bound + rc->srgb.range_size - 1)
+			if (rcap->srgb.range_size == 0
+			    || (rcap->srgb.lower_bound <= MPLS_LABEL_RESERVED_MAX)
+			    || ((rcap->srgb.lower_bound + rcap->srgb.range_size - 1)
 				> MPLS_LABEL_UNRESERVED_MAX)) {
 				sbuf_push(log, indent, "Invalid label range. Reset SRGB\n");
-				rc->srgb.lower_bound = 0;
-				rc->srgb.range_size = 0;
+				rcap->srgb.lower_bound = 0;
+				rcap->srgb.range_size = 0;
 			}
 			break;
 		case ISIS_SUBTLV_ALGORITHM:
 			/* Only 2 algorithms are supported: SPF & Strict SPF */
-			stream_get(&rc->algo, s,
+			stream_get(&rcap->algo, s,
 				   length > SR_ALGORITHM_COUNT
 					   ? SR_ALGORITHM_COUNT
 					   : length);
@@ -2789,12 +2813,39 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
 				stream_forward_getp(
 					s, length - SR_ALGORITHM_COUNT);
 			break;
+		case ISIS_SUBTLV_SRLB:
+			/* RFC 8667 section #3.3: Only one SRLB is authorized */
+			if (rcap->srlb.range_size != 0) {
+				stream_forward_getp(s, length);
+				continue;
+			}
+			/* Ignore Flags which are not defined */
+			stream_getc(s);
+			rcap->srlb.range_size = stream_get3(s);
+			/* Skip Type and get Length of SID Label */
+			stream_getc(s);
+			sid_len = stream_getc(s);
+			if (sid_len == ISIS_SUBTLV_SID_LABEL_SIZE)
+				rcap->srlb.lower_bound = stream_get3(s);
+			else
+				rcap->srlb.lower_bound = stream_getl(s);
+
+			/* SRLB sanity checks. */
+			if (rcap->srlb.range_size == 0
+			    || (rcap->srlb.lower_bound <= MPLS_LABEL_RESERVED_MAX)
+			    || ((rcap->srlb.lower_bound + rcap->srlb.range_size - 1)
+				> MPLS_LABEL_UNRESERVED_MAX)) {
+				sbuf_push(log, indent, "Invalid label range. Reset SRLB\n");
+				rcap->srlb.lower_bound = 0;
+				rcap->srlb.range_size = 0;
+			}
+			break;
 		case ISIS_SUBTLV_NODE_MSD:
 			msd_type = stream_getc(s);
-			rc->msd = stream_getc(s);
+			rcap->msd = stream_getc(s);
 			/* Only BMI-MSD type has been defined in RFC 8491 */
 			if (msd_type != MSD_TYPE_BASE_MPLS_IMPOSITION)
-				rc->msd = 0;
+				rcap->msd = 0;
 			break;
 		default:
 			stream_forward_getp(s, length);
@@ -2802,6 +2853,7 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
 		}
 		subtlv_len = subtlv_len - length - 2;
 	}
+	tlvs->router_cap = rcap;
 	return 0;
 }