[U-Boot] [PATCH 1/2] [RFC]new command: wol - Wake on LAN

[Lothar Felten]

This patch adds a new command 'wol': It waits for an incoming
Wake-on-LAN
packet or times out if no WoL packed is received.
If the WoL packet contains a password, it is saved in the environment
variable 'wolpassword' using the etherwake format (dot separated
decimals).

Intended use case: a networked device should boot an alternate image.
It's attached to a network on a client site, modifying the DHCP server
configuration or setup of a tftp server is not allowed.
After power on the device waits a few seconds for a WoL packet. If a
packet is received, the device boots the alternate image. Otherwise
it boots the default image.

This method is a simple way to interact with a system via network even
if only the MAC address is known. Tools to send WoL packets are
available on all common platforms.

Signed-off-by: Lothar Felten <lothar.felten at gmail.com>
---
 net/wol.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 net/wol.h | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 net/wol.c
 create mode 100644 net/wol.h

diff --git a/net/wol.c b/net/wol.c
new file mode 100644
index 0000000000..0cedbaed85
--- /dev/null
+++ b/net/wol.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2018 Lothar Felten, lothar.felten at gmail.com
+ */
+
+#include <common.h>
+#include <command.h>
+#include <net.h>
+#include "wol.h"
+
+/*
+ *	Handle a received wake-on-lan packet.
+ */
+void wol_receive(struct ip_udp_hdr *ip, unsigned int len)
+{
+	char buf[4];
+	int i;
+	struct wol_hdr *wol;
+
+	wol = (struct wol_hdr *)ip;
+
+	if (len < 102)
+		return;
+
+	for (i = 0; i < 6; i++)
+		if (wol->wol_sync[i] != 0xff)
+			return;
+
+	for (i = 0; i < 16; i++)
+		if (memcmp(&wol->wol_dest[i * 6], net_ethaddr, 6) != 0)
+			return;
+
+	/* save the optional password using the etherwake format */
+	if (len >= 106) {
+		sprintf(buf, "%i.%i.%i.%i",
+			wol->wol_passwd[0], wol->wol_passwd[1],
+			wol->wol_passwd[2], wol->wol_passwd[3]);
+		env_set("wolpassword", buf);
+	}
+	net_set_state(NETLOOP_SUCCESS);
+}
+
+static void wol_timeout_handler(void)
+{
+	eth_halt();
+	net_set_state(NETLOOP_FAIL);
+}
+
+void wol_start(void)
+{
+	ulong timeout = env_get_ulong("woltimeout", 10, 5);
+
+	net_set_timeout_handler(timeout * 1000, wol_timeout_handler);
+}
diff --git a/net/wol.h b/net/wol.h
new file mode 100644
index 0000000000..e34767c733
--- /dev/null
+++ b/net/wol.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2018 Lothar Felten, lothar.felten at gmail.com
+ */
+
+#if defined(CONFIG_CMD_WOL)
+
+#ifndef __WOL_H__
+#define __WOL_H__
+
+#include <net.h>
+
+/**********************************************************************/
+
+/*
+ *	Wake-on-LAN header.
+ */
+struct wol_hdr {
+	u8	wol_sync[6];		/* sync bytes			*/
+	u8	wol_dest[16 * 6];	/* 16x destination MAC address	*/
+	u8	wol_passwd[4];		/* optional password		*/
+};
+
+/*
+ * Initialize wol (beginning of netloop)
+ */
+void wol_start(void);
+
+/*
+ * Deal with the receipt of a wol packet
+ *
+ * @param ip IP header in the packet
+ * @param len Packet length
+ */
+void wol_receive(struct ip_udp_hdr *ip, unsigned int len);
+
+/**********************************************************************/
+
+#endif /* __WOL_H__ */
+#endif
-- 
2.14.1