lib,isisd: refactor igp-agnostic sr misc functions

SR Algorithms are independent of specific IGPs
such as IS-IS. This commit adds lib/sr to
aggregate IGP agnostic functions and constants.

Signed-off-by: Hiroki Shirokura <hiroki.shirokura@linecorp.com>
Signed-off-by: Philippe Guibert <philippe.guibert@6wind.com>
Signed-off-by: Louis Scalbert <louis.scalbert@6wind.com>

isisd/isis_te.c

@@ -611,7 +611,7 @@ static struct ls_vertex *lsp_to_vertex(struct ls_ted *ted, struct isis_lsp *lsp)
 				lnode.srgb.flag = cap->srgb.flags;
 				lnode.srgb.lower_bound = cap->srgb.lower_bound;
 				lnode.srgb.range_size = cap->srgb.range_size;
-				for (int i = 0; i < SR_ALGORITHM_COUNT; i++)
+				for (int i = 0; i < LIB_LS_SR_ALGO_COUNT; i++)
 					lnode.algo[i] = cap->algo[i];
 			}
 

isisd/isis_tlvs.c

@@ -3552,9 +3552,8 @@ static void format_tlv_router_cap(const struct isis_router_cap *router_cap,
 		for (int i = 0; i < SR_ALGORITHM_COUNT; i++)
 			if (router_cap->algo[i] != SR_ALGORITHM_UNSET)
 				sbuf_push(buf, indent, "    %u: %s\n", i,
-					  router_cap->algo[i] == 0
+					  sr_algorithm_string(
-						  ? "SPF"
+						  router_cap->algo[i]));
-						  : "Strict SPF");
 	}
 
 	/* Segment Routing Node MSD as per RFC8491 section #2 */
@@ -3573,7 +3572,7 @@ static int pack_tlv_router_cap(const struct isis_router_cap *router_cap,
 {
 	size_t tlv_len = ISIS_ROUTER_CAP_SIZE;
 	size_t len_pos;
-	uint8_t nb_algo;
+	uint16_t nb_algo;
 
 	if (!router_cap)
 		return 0;
@@ -3757,13 +3756,9 @@ static int unpack_tlv_router_cap(enum isis_tlv_context context,
 			if (length == 0)
 				break;
 			/* Only 2 algorithms are supported: SPF & Strict SPF */
-			stream_get(&rcap->algo, s,
+			stream_get(&rcap->algo, s, length > 2 ? 2 : length);
-				   length > SR_ALGORITHM_COUNT
+			if (length > 2)
-					   ? SR_ALGORITHM_COUNT
+				stream_forward_getp(s, length - 2);
-					   : length);
-			if (length > SR_ALGORITHM_COUNT)
-				stream_forward_getp(
-					s, length - SR_ALGORITHM_COUNT);
 			break;
 		case ISIS_SUBTLV_SRLB:
 			/* Check that SRLB is correctly formated */

isisd/isis_tlvs.h

@@ -9,6 +9,7 @@
 #ifndef ISIS_TLVS_H
 #define ISIS_TLVS_H
 
+#include "segment_routing.h"
 #include "openbsd-tree.h"
 #include "prefix.h"
 
@@ -177,16 +178,6 @@ struct isis_lan_adj_sid {
 #define ISIS_ROUTER_CAP_FLAG_D	0x02
 #define ISIS_ROUTER_CAP_SIZE	5
 
-/* Number of supported algorithm for Segment Routing.
- * Right now only 2 have been standardized:
- *  - 0: SPF
- *  - 1: Strict SPF
- */
-#define SR_ALGORITHM_COUNT	2
-#define SR_ALGORITHM_SPF	0
-#define SR_ALGORITHM_STRICT_SPF	1
-#define SR_ALGORITHM_UNSET	255
-
 #define MSD_TYPE_BASE_MPLS_IMPOSITION  0x01
 #define MSD_TLV_SIZE            2
 

lib/link_state.h

@@ -92,6 +92,9 @@ struct ls_node_id {
  */
 extern int ls_node_id_same(struct ls_node_id i1, struct ls_node_id i2);
 
+/* Supported number of algorithm by the link-state library */
+#define LIB_LS_SR_ALGO_COUNT 2
+
 /* Link State flags to indicate which Node parameters are valid */
 #define LS_NODE_UNSET		0x0000
 #define LS_NODE_NAME		0x0001
@@ -123,7 +126,7 @@ struct ls_node {
 		uint32_t lower_bound;		/* MPLS label lower bound */
 		uint32_t range_size;		/* MPLS label range size */
 	} srlb;
-	uint8_t algo[2];		/* Segment Routing Algorithms */
+	uint8_t algo[LIB_LS_SR_ALGO_COUNT]; /* Segment Routing Algorithms */
 	uint8_t msd;			/* Maximum Stack Depth */
 };
 

lib/segment_routing.c

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*********************************************************************
+ * Copyright 2022 Hiroki Shirokura, LINE Corporation
+ * Copyright 2022 Masakazu Asama
+ * Copyright 2022 6WIND S.A.
+ *
+ * segment_routing.c: Segment-Routing Library
+ *
+ * Authors
+ * -------
+ * Hiroki Shirokura
+ * Masakazu Asama
+ * Louis Scalbert
+ */
+
+#include "segment_routing.h"
+
+const char *sr_algorithm_string(uint8_t algo)
+{
+	switch (algo) {
+	case SR_ALGORITHM_SPF:
+		return "SPF";
+	case SR_ALGORITHM_STRICT_SPF:
+		return "Strict SPF";
+	case SR_ALGORITHM_UNSET:
+		return "Unset";
+	default:
+		return algo >= SR_ALGORITHM_FLEX_MIN ? "Flex-Algo" : "Unknown";
+	}
+}

lib/segment_routing.h

@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*********************************************************************
+ * Copyright 2022 Hiroki Shirokura, LINE Corporation
+ * Copyright 2022 Masakazu Asama
+ * Copyright 2022 6WIND S.A.
+ *
+ * segment_routing.h: Segment-Routing Library
+ *
+ * Authors
+ * -------
+ * Hiroki Shirokura
+ * Masakazu Asama
+ * Louis Scalbert
+ */
+
+#ifndef _FRR_SR_H
+#define _FRR_SR_H
+
+#include <zebra.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * IGP Algorithm Types
+ * https://www.iana.org/assignments/igp-parameters/igp-parameters.xhtml
+ */
+#define SR_ALGORITHM_SPF 0	/* RFC8665 */
+#define SR_ALGORITHM_STRICT_SPF 1 /* RFC8665 */
+#define SR_ALGORITHM_UNSET 127    /* FRRouting defined */
+#define SR_ALGORITHM_FLEX_MIN 128 /* RFC9350 Flex-Algorithm */
+#define SR_ALGORITHM_FLEX_MAX 255 /* RFC9350 Flex-Algorithm */
+#define SR_ALGORITHM_COUNT 256
+
+const char *sr_algorithm_string(uint8_t algo);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _FRR_SR_H */

lib/subdir.am

@@ -99,6 +99,7 @@ lib_libfrr_la_SOURCES = \
 	lib/sockopt.c \
 	lib/sockunion.c \
 	lib/spf_backoff.c \
+	lib/segment_routing.c \
 	lib/srcdest_table.c \
 	lib/stream.c \
 	lib/strformat.c \
@@ -282,6 +283,7 @@ pkginclude_HEADERS += \
 	lib/sockopt.h \
 	lib/sockunion.h \
 	lib/spf_backoff.h \
+	lib/segment_routing.h \
 	lib/srcdest_table.h \
 	lib/srte.h \
 	lib/stream.h \