bgpd: prefix-sid srv6 l3vpn service tlv

bgpd already supports BGP Prefix-SID path attribute and
there are some sub-types of Prefix-SID path attribute.
This commits makes bgpd to support additional sub-types.
sub-Type-4 and sub-Type-5 for construct the VPNv4 SRv6 backend
with vpnv4-unicast address family.
This path attributes is already supported by Ciscos IOS-XR and NX-OS.

Prefix-SID sub-Type-4 and sub-Type-5 is defined on following
IETF-drafts.

Supports(A-part-of):
- https://tools.ietf.org/html/draft-dawra-idr-srv6-vpn-04
- https://tools.ietf.org/html/draft-dawra-idr-srv6-vpn-05

Signed-off-by: Hiroki Shirokura <slank.dev@gmail.com>

3 files changed, 251 insertions, 0 deletions

diff --git a/lib/srv6.c b/lib/srv6.c
new file mode 100644
index 000000000..be340f13f
--- /dev/null
+++ b/lib/srv6.c
@@ -0,0 +1,116 @@
+/*
+ * SRv6 definitions
+ * Copyright (C) 2020  Hiroki Shirokura, LINE Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "srv6.h"
+#include "log.h"
+
+const char *seg6local_action2str(uint32_t action)
+{
+	switch (action) {
+	case ZEBRA_SEG6_LOCAL_ACTION_END:
+		return "End";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_X:
+		return "End.X";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_T:
+		return "End.T";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DX2:
+		return "End.DX2";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DX6:
+		return "End.DX6";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DX4:
+		return "End.DX4";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DT6:
+		return "End.DT6";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DT4:
+		return "End.DT4";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_B6:
+		return "End.B6";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_B6_ENCAP:
+		return "End.B6.Encap";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_BM:
+		return "End.BM";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_S:
+		return "End.S";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_AS:
+		return "End.AS";
+	case ZEBRA_SEG6_LOCAL_ACTION_END_AM:
+		return "End.AM";
+	case ZEBRA_SEG6_LOCAL_ACTION_UNSPEC:
+		return "unspec";
+	default:
+		return "unknown";
+	}
+}
+
+int snprintf_seg6_segs(char *str,
+		size_t size, const struct seg6_segs *segs)
+{
+	str[0] = '\0';
+	for (size_t i = 0; i < segs->num_segs; i++) {
+		char addr[INET6_ADDRSTRLEN];
+		bool not_last = (i + 1) < segs->num_segs;
+
+		inet_ntop(AF_INET6, &segs->segs[i], addr, sizeof(addr));
+		strlcat(str, addr, size);
+		strlcat(str, not_last ? "," : "", size);
+	}
+	return strlen(str);
+}
+
+const char *seg6local_context2str(char *str, size_t size,
+		struct seg6local_context *ctx, uint32_t action)
+{
+	char b0[128];
+
+	switch (action) {
+
+	case ZEBRA_SEG6_LOCAL_ACTION_END:
+		snprintf(str, size, "USP");
+		return str;
+
+	case ZEBRA_SEG6_LOCAL_ACTION_END_X:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DX6:
+		inet_ntop(AF_INET6, &ctx->nh6, b0, 128);
+		snprintf(str, size, "nh6 %s", b0);
+		return str;
+
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DX4:
+		inet_ntop(AF_INET, &ctx->nh4, b0, 128);
+		snprintf(str, size, "nh4 %s", b0);
+		return str;
+
+	case ZEBRA_SEG6_LOCAL_ACTION_END_T:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DT6:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DT4:
+		snprintf(str, size, "table %u", ctx->table);
+		return str;
+
+	case ZEBRA_SEG6_LOCAL_ACTION_END_DX2:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_B6:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_B6_ENCAP:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_BM:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_S:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_AS:
+	case ZEBRA_SEG6_LOCAL_ACTION_END_AM:
+	case ZEBRA_SEG6_LOCAL_ACTION_UNSPEC:
+	default:
+		snprintf(str, size, "unknown(%s)", __func__);
+		return str;
+	}
+}
diff --git a/lib/srv6.h b/lib/srv6.h
new file mode 100644
index 000000000..24c7ffc3a
--- /dev/null
+++ b/lib/srv6.h
@@ -0,0 +1,133 @@
+/*
+ * SRv6 definitions
+ * Copyright (C) 2020  Hiroki Shirokura, LINE Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; see the file COPYING; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef _FRR_SRV6_H
+#define _FRR_SRV6_H
+
+#include <zebra.h>
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#define SRV6_MAX_SIDS 16
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define sid2str(sid, str, size) \
+	inet_ntop(AF_INET6, sid, str, size)
+
+enum seg6_mode_t {
+	INLINE,
+	ENCAP,
+	L2ENCAP,
+};
+
+enum seg6local_action_t {
+	ZEBRA_SEG6_LOCAL_ACTION_UNSPEC       = 0,
+	ZEBRA_SEG6_LOCAL_ACTION_END          = 1,
+	ZEBRA_SEG6_LOCAL_ACTION_END_X        = 2,
+	ZEBRA_SEG6_LOCAL_ACTION_END_T        = 3,
+	ZEBRA_SEG6_LOCAL_ACTION_END_DX2      = 4,
+	ZEBRA_SEG6_LOCAL_ACTION_END_DX6      = 5,
+	ZEBRA_SEG6_LOCAL_ACTION_END_DX4      = 6,
+	ZEBRA_SEG6_LOCAL_ACTION_END_DT6      = 7,
+	ZEBRA_SEG6_LOCAL_ACTION_END_DT4      = 8,
+	ZEBRA_SEG6_LOCAL_ACTION_END_B6       = 9,
+	ZEBRA_SEG6_LOCAL_ACTION_END_B6_ENCAP = 10,
+	ZEBRA_SEG6_LOCAL_ACTION_END_BM       = 11,
+	ZEBRA_SEG6_LOCAL_ACTION_END_S        = 12,
+	ZEBRA_SEG6_LOCAL_ACTION_END_AS       = 13,
+	ZEBRA_SEG6_LOCAL_ACTION_END_AM       = 14,
+	ZEBRA_SEG6_LOCAL_ACTION_END_BPF      = 15,
+};
+
+struct seg6_segs {
+	size_t num_segs;
+	struct in6_addr segs[256];
+};
+
+struct seg6local_context {
+	struct in_addr nh4;
+	struct in6_addr nh6;
+	uint32_t table;
+};
+
+static inline const char *seg6_mode2str(enum seg6_mode_t mode)
+{
+	switch (mode) {
+	case INLINE:
+		return "INLINE";
+	case ENCAP:
+		return "ENCAP";
+	case L2ENCAP:
+		return "L2ENCAP";
+	default:
+		return "unknown";
+	}
+}
+
+static inline bool sid_same(
+		const struct in6_addr *a,
+		const struct in6_addr *b)
+{
+	if (!a && !b)
+		return true;
+	else if (!(a && b))
+		return false;
+	else
+		return memcmp(a, b, sizeof(struct in6_addr)) == 0;
+}
+
+static inline bool sid_diff(
+		const struct in6_addr *a,
+		const struct in6_addr *b)
+{
+	return !sid_same(a, b);
+}
+
+static inline bool sid_zero(
+		const struct in6_addr *a)
+{
+	struct in6_addr zero = {};
+
+	return sid_same(a, &zero);
+}
+
+static inline void *sid_copy(struct in6_addr *dst,
+		const struct in6_addr *src)
+{
+	return memcpy(dst, src, sizeof(struct in6_addr));
+}
+
+const char *
+seg6local_action2str(uint32_t action);
+
+const char *
+seg6local_context2str(char *str, size_t size,
+		struct seg6local_context *ctx, uint32_t action);
+
+int snprintf_seg6_segs(char *str,
+		size_t size, const struct seg6_segs *segs);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/lib/subdir.am b/lib/subdir.am
index cb6fa7a3b..d804d839d 100644
--- a/lib/subdir.am
+++ b/lib/subdir.am
@@ -51,6 +51,7 @@ lib_libfrr_la_SOURCES = \
 	lib/mlag.c \
 	lib/module.c \
 	lib/mpls.c \
+	lib/srv6.c \
 	lib/network.c \
 	lib/nexthop.c \
 	lib/netns_linux.c \
@@ -193,6 +194,7 @@ pkginclude_HEADERS += \
 	lib/module.h \
 	lib/monotime.h \
 	lib/mpls.h \
+	lib/srv6.h \
 	lib/network.h \
 	lib/nexthop.h \
 	lib/nexthop_group.h \