net: ipv6: Add Neighbor Discovery Protocol (NDP)

Implement basic of NDP. It doesn't include such things as Router
Solicitation, Router Advertisement and Redirect. It just has Neighbor
Solicitation and Neighbor Advertisement. Only these two features are used
in u-boot IPv6. Implementation of some NDP functions uses API that was
exposed in "net: ipv6: Add IPv6 basic primitives".

Also this patch inlcudes update in Makefile to build NDP.

Series-changes: 3
- Added structures and functions descriptions
- Fixed style problems

Series-changes: 4
- Fixed structures and functions description style

Signed-off-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 102 insertions, 0 deletions

diff --git a/include/ndisc.h b/include/ndisc.h
new file mode 100644
index 0000000000..f6f8eb6507
--- /dev/null
+++ b/include/ndisc.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2013 Allied Telesis Labs NZ
+ * Chris Packham, <judge.packham@gmail.com>
+ *
+ * Copyright (C) 2022 YADRO
+ * Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
+ */
+
+#ifndef __NDISC_H__
+#define __NDISC_H__
+
+#include <ndisc.h>
+
+/* struct nd_msg - ICMPv6 Neighbour Discovery message format */
+struct nd_msg {
+	struct icmp6hdr	icmph;
+	struct in6_addr	target;
+	__u8		opt[0];
+};
+
+/* struct echo_msg - ICMPv6 echo request/reply message format */
+struct echo_msg {
+	struct icmp6hdr	icmph;
+	__u16		id;
+	__u16		sequence;
+};
+
+/* Neigbour Discovery option types */
+enum {
+	__ND_OPT_PREFIX_INFO_END	= 0,
+	ND_OPT_SOURCE_LL_ADDR		= 1,
+	ND_OPT_TARGET_LL_ADDR		= 2,
+	ND_OPT_PREFIX_INFO		= 3,
+	ND_OPT_REDIRECT_HDR		= 4,
+	ND_OPT_MTU			= 5,
+	__ND_OPT_MAX
+};
+
+/* IPv6 destination address of packet waiting for ND */
+extern struct in6_addr net_nd_sol_packet_ip6;
+/* MAC destination address of packet waiting for ND */
+extern uchar *net_nd_packet_mac;
+/* pointer to packet waiting to be transmitted after ND is resolved */
+extern uchar *net_nd_tx_packet;
+/* size of packet waiting to be transmitted */
+extern int net_nd_tx_packet_size;
+/* the timer for ND resolution */
+extern ulong net_nd_timer_start;
+/* the number of requests we have sent so far */
+extern int net_nd_try;
+
+#ifdef CONFIG_IPV6
+/**
+ * ndisc_init() - Make initial steps for ND state machine.
+ * Usually move variables into initial state.
+ */
+void ndisc_init(void);
+
+/**
+ * ndisc_receive() - Handle ND packet
+ *
+ * @et:		pointer to incoming packet
+ * @ip6:	pointer to IPv6 header
+ * @len:	incoming packet length
+ * Return: 0 if handle successfully, -1 if unsupported/unknown ND packet type
+ */
+int ndisc_receive(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len);
+
+/**
+ * ndisc_request() - Send ND request
+ */
+void ndisc_request(void);
+
+/**
+ * ndisc_init() - Check ND response timeout
+ *
+ * Return: 0 if no timeout, -1 otherwise
+ */
+int ndisc_timeout_check(void);
+#else
+static inline void ndisc_init(void)
+{
+}
+
+static inline int
+ndisc_receive(struct ethernet_hdr *et, struct ip6_hdr *ip6, int len)
+{
+	return -1;
+}
+
+static inline void ndisc_request(void)
+{
+}
+
+static inline int ndisc_timeout_check(void)
+{
+	return 0;
+}
+#endif
+
+#endif /* __NDISC_H__ */