[PATCH 2/3] fastboot net: implement fastboot over UDP

["Daniel Glöckner" <dg@emlix.com>]

From: Edmund Henniges <eh@emlix.com>

This implements the UDP variant of the fastboot protocol. The only way to
start the service for now is to compile with CONFIG_FASTBOOT_NET_ON_BOOT.
The service will bind to the network interface that provides the IPv4
gateway.

Sending an OKAY packet before performing a restart is necessary since
contrary to USB the host will not notice when a UDP server disappears.

Signed-off-by: Edmund Henniges <eh@emlix.com>
Signed-off-by: Daniel Glöckner <dg@emlix.com>
---
 common/fastboot.c      |   3 +
 include/fastboot.h     |   1 +
 include/fastboot_net.h |  12 ++
 net/Kconfig            |  17 ++
 net/Makefile           |   1 +
 net/fastboot.c         | 437 +++++++++++++++++++++++++++++++++++++++++
 6 files changed, 471 insertions(+)
 create mode 100644 include/fastboot_net.h
 create mode 100644 net/fastboot.c

diff --git a/common/fastboot.c b/common/fastboot.c
index 58a095efa..4a11ac54b 100644
--- a/common/fastboot.c
+++ b/common/fastboot.c
@@ -245,6 +245,7 @@ static char *fastboot_msg[] = {
 	[FASTBOOT_MSG_FAIL] = "FAIL",
 	[FASTBOOT_MSG_INFO] = "INFO",
 	[FASTBOOT_MSG_DATA] = "DATA",
+	[FASTBOOT_MSG_NONE] = "",
 };
 
 int fastboot_tx_print(struct fastboot *fb, enum fastboot_msg_type type,
@@ -273,6 +274,7 @@ int fastboot_tx_print(struct fastboot *fb, enum fastboot_msg_type type,
 	case FASTBOOT_MSG_INFO:
 		pr_info("%pV\n", &vaf);
 		break;
+	case FASTBOOT_MSG_NONE:
 	case FASTBOOT_MSG_DATA:
 		break;
 	}
@@ -287,6 +289,7 @@ int fastboot_tx_print(struct fastboot *fb, enum fastboot_msg_type type,
 
 static void cb_reboot(struct fastboot *fb, const char *cmd)
 {
+	fastboot_tx_print(fb, FASTBOOT_MSG_OKAY, "");
 	restart_machine();
 }
 
diff --git a/include/fastboot.h b/include/fastboot.h
index 3b6cae8a5..503d21bc7 100644
--- a/include/fastboot.h
+++ b/include/fastboot.h
@@ -51,6 +51,7 @@ enum fastboot_msg_type {
 	FASTBOOT_MSG_FAIL,
 	FASTBOOT_MSG_INFO,
 	FASTBOOT_MSG_DATA,
+	FASTBOOT_MSG_NONE,
 };
 
 int fastboot_generic_init(struct fastboot *fb, bool export_bbu);
diff --git a/include/fastboot_net.h b/include/fastboot_net.h
new file mode 100644
index 000000000..e4b9d9809
--- /dev/null
+++ b/include/fastboot_net.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+#ifndef __FASTBOOT_NET__
+#define __FASTBOOT_NET__
+
+#include <fastboot.h>
+
+struct fastboot_net;
+
+struct fastboot_net *fastboot_net_init(struct fastboot_opts *opts);
+void fastboot_net_free(struct fastboot_net *fbn);
+
+#endif
diff --git a/net/Kconfig b/net/Kconfig
index 12b6bdb56..aaf621559 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -31,4 +31,21 @@ config NET_SNTP
 	bool
 	prompt "sntp support"
 
+config NET_FASTBOOT
+	bool
+	select BANNER
+	select FILE_LIST
+	select FASTBOOT_BASE
+	prompt "Android Fastboot support"
+	help
+	  This option adds support for the UDP variant of the Fastboot
+	  protocol.
+
+config FASTBOOT_NET_ON_BOOT
+	bool
+	depends on NET_FASTBOOT
+	prompt "Start network fastboot during boot"
+	help
+	  Automatically starts the network and listens for Fastboot packets.
+	  The list of accessible files is taken from nv.fastboot.files.
 endif
diff --git a/net/Makefile b/net/Makefile
index eb8d43915..962b2dec5 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_CMD_PING)	+= ping.o
 obj-$(CONFIG_NET_RESOLV)+= dns.o
 obj-$(CONFIG_NET_NETCONSOLE) += netconsole.o
 obj-$(CONFIG_NET_IFUP)	+= ifup.o
+obj-$(CONFIG_NET_FASTBOOT) += fastboot.o
diff --git a/net/fastboot.c b/net/fastboot.c
new file mode 100644
index 000000000..41d1859ab
--- /dev/null
+++ b/net/fastboot.c
@@ -0,0 +1,437 @@
+// SPDX-License-Identifier: BSD-2-Clause
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Copyright 2020 Edmund Henniges <eh@emlix.com>
+ * Copyright 2020 Daniel Glöckner <dg@emlix.com>
+ * Ported from U-Boot to Barebox
+ */
+
+#define pr_fmt(fmt) "net fastboot: " fmt
+
+#include <common.h>
+#include <net.h>
+#include <fastboot.h>
+#include <fastboot_net.h>
+#include <environment.h>
+#include <progress.h>
+#include <unistd.h>
+#include <init.h>
+
+#define FASTBOOT_PORT 5554
+#define MAX_MTU 1500
+#define PACKET_SIZE (min(PKTSIZE, MAX_MTU + ETHER_HDR_SIZE) \
+		      - (net_eth_to_udp_payload(0) - (char *)0))
+
+enum {
+	FASTBOOT_ERROR = 0,
+	FASTBOOT_QUERY = 1,
+	FASTBOOT_INIT = 2,
+	FASTBOOT_FASTBOOT = 3,
+};
+
+struct __packed fastboot_header {
+	uint8_t id;
+	uint8_t flags;
+	uint16_t seq;
+};
+
+struct fastboot_net {
+	struct fastboot fastboot;
+
+	struct net_connection *net_con;
+	struct fastboot_header response_header;
+	struct poller_struct poller;
+	bool active_download;
+	bool reinit;
+	bool may_print;
+	char command[65];
+
+	IPaddr_t host_addr;
+	uint16_t host_port;
+	uint8_t host_mac[ETH_ALEN];
+	uint16_t sequence_number;
+	uint16_t last_payload_len;
+	uchar last_payload[64 + sizeof(struct fastboot_header)];
+};
+
+static const ushort udp_version = 1;
+
+static bool is_current_connection(struct fastboot_net *fbn)
+{
+	return fbn->host_addr == net_read_ip(&fbn->net_con->ip->daddr) &&
+	       fbn->host_port == fbn->net_con->udp->uh_dport;
+}
+
+static void fastboot_send(struct fastboot_net *fbn,
+			  struct fastboot_header header,
+			  const char *error_msg)
+{
+	short tmp;
+	uchar *packet = net_udp_get_payload(fbn->net_con);
+	uchar *packet_base = packet;
+	bool current_session = false;;
+
+	if (fbn->sequence_number == ntohs(header.seq) &&
+	    is_current_connection(fbn))
+		current_session = true;
+
+	if (error_msg)
+		header.id = FASTBOOT_ERROR;
+
+	/* send header */
+	memcpy(packet, &header, sizeof(header));
+	packet += sizeof(header);
+
+	switch (header.id) {
+	case FASTBOOT_QUERY:
+		/* send sequence number */
+		tmp = htons(fbn->sequence_number);
+		memcpy(packet, &tmp, sizeof(tmp));
+		packet += sizeof(tmp);
+		break;
+	case FASTBOOT_INIT:
+		/* send udp version and packet size */
+		tmp = htons(udp_version);
+		memcpy(packet, &tmp, sizeof(tmp));
+		packet += sizeof(tmp);
+		tmp = htons(PACKET_SIZE);
+		memcpy(packet, &tmp, sizeof(tmp));
+		packet += sizeof(tmp);
+		break;
+	case FASTBOOT_ERROR:
+		pr_err("%s\n", error_msg);
+
+		/* send error message */
+		tmp = strlen(error_msg);
+		memcpy(packet, error_msg, tmp);
+		packet += tmp;
+
+		if (current_session) {
+			fbn->fastboot.active = false;
+			fbn->active_download = false;
+			fbn->reinit = true;
+		}
+		break;
+	}
+
+	if (current_session && header.id != FASTBOOT_QUERY) {
+		fbn->sequence_number++;
+		fbn->last_payload_len = packet - packet_base;
+		memcpy(fbn->last_payload, packet_base, fbn->last_payload_len);
+	}
+	net_udp_send(fbn->net_con, packet - packet_base);
+}
+
+static int fastboot_write_net(struct fastboot *fb, const char *buf, unsigned int n)
+{
+	struct fastboot_net *fbn = container_of(fb, struct fastboot_net,
+						fastboot);
+	struct fastboot_header response_header;
+	uchar *packet;
+	uchar *packet_base;
+
+	if (fbn->reinit)
+		return 0;
+
+	while (!fbn->may_print) {
+		net_poll();
+		if (fbn->reinit)
+			return 0;
+	}
+
+	response_header = fbn->response_header;
+	response_header.flags = 0;
+	response_header.seq = htons(fbn->sequence_number);
+	++fbn->sequence_number;
+	fbn->may_print = false;
+
+	packet = net_udp_get_payload(fbn->net_con);
+	packet_base = packet;
+
+	/* Write headers */
+	memcpy(packet, &response_header, sizeof(response_header));
+	packet += sizeof(response_header);
+	/* Write response */
+	memcpy(packet, buf, n);
+	packet += n;
+
+	/* Save packet for retransmitting */
+	fbn->last_payload_len = packet - packet_base;
+	memcpy(fbn->last_payload, packet_base, fbn->last_payload_len);
+
+	memcpy(fbn->net_con->et->et_dest, fbn->host_mac, ETH_ALEN);
+	net_write_ip(&fbn->net_con->ip->daddr, fbn->host_addr);
+	fbn->net_con->udp->uh_dport = fbn->host_port;
+	net_udp_send(fbn->net_con, fbn->last_payload_len);
+
+	return 0;
+}
+
+static void fastboot_start_download_net(struct fastboot *fb)
+{
+	struct fastboot_net *fbn = container_of(fb, struct fastboot_net,
+						fastboot);
+
+	fastboot_start_download_generic(fb);
+	fbn->active_download = true;
+}
+
+/* must send exactly one packet on all code paths */
+static void fastboot_data_download(struct fastboot_net *fbn,
+			const void *fastboot_data,
+			unsigned int fastboot_data_len)
+{
+	int ret;
+
+	if (fastboot_data_len == 0 ||
+	    (fbn->fastboot.download_bytes + fastboot_data_len) >
+	    fbn->fastboot.download_size) {
+		fastboot_send(fbn, fbn->response_header,
+			      "Received invalid data length");
+		return;
+	}
+
+	ret = fastboot_handle_download_data(&fbn->fastboot, fastboot_data,
+					    fastboot_data_len);
+	if (ret < 0) {
+		fastboot_send(fbn, fbn->response_header, strerror(-ret));
+		return;
+	}
+
+	fastboot_tx_print(&fbn->fastboot, FASTBOOT_MSG_NONE, "");
+}
+
+static void fastboot_handle_type_fastboot(struct fastboot_net *fbn,
+					  struct fastboot_header header,
+					  char *fastboot_data,
+					  unsigned int fastboot_data_len)
+{
+	fbn->response_header = header;
+	fbn->may_print = true;
+	if (fbn->active_download) {
+		if (!fastboot_data_len && fbn->fastboot.download_bytes
+					   == fbn->fastboot.download_size) {
+			/*
+			 * Can't call fastboot_download_finished here
+			 * because it will call fastboot_tx_print
+			 * multiple times.
+			 */
+			fbn->active_download = false;
+		} else {
+			fastboot_data_download(fbn, fastboot_data,
+					       fastboot_data_len);
+		}
+	} else if (!fbn->command[0]) {
+		if (fastboot_data_len >= sizeof(fbn->command)) {
+			fastboot_send(fbn, header, "command too long");
+		} else {
+			memcpy(fbn->command, fastboot_data, fastboot_data_len);
+			fbn->command[fastboot_data_len] = 0;
+		}
+	}
+
+	if (!fbn->fastboot.active)
+		fbn->active_download = false;
+}
+
+static void fastboot_check_retransmit(struct fastboot_net *fbn,
+				      struct fastboot_header header)
+{
+	if (ntohs(header.seq) == fbn->sequence_number - 1 &&
+	    is_current_connection(fbn)) {
+		/* Retransmit last sent packet */
+		memcpy(net_udp_get_payload(fbn->net_con),
+		       fbn->last_payload, fbn->last_payload_len);
+		net_udp_send(fbn->net_con, fbn->last_payload_len);
+	}
+}
+
+static void fastboot_handler(void *ctx, char *packet, unsigned int raw_len)
+{
+	unsigned int len = net_eth_to_udplen(packet);
+	struct ethernet *eth_header = (struct ethernet *)packet;
+	struct iphdr *ip_header = net_eth_to_iphdr(packet);
+	struct udphdr *udp_header = net_eth_to_udphdr(packet);
+	char *payload = net_eth_to_udp_payload(packet);
+	struct fastboot_net *fbn = ctx;
+	struct fastboot_header header;
+	char *fastboot_data = payload + sizeof(header);
+	uint16_t tot_len = ntohs(ip_header->tot_len);
+
+	/* catch bogus tot_len values */
+	if ((char *)ip_header - packet + tot_len > raw_len)
+		return;
+
+	/* catch packets split into fragments that are too small to reply */
+	if (fastboot_data - (char *)ip_header > tot_len)
+		return;
+
+	/* catch packets too small to be valid */
+	if (len < sizeof(struct fastboot_header))
+		return;
+
+	memcpy(&header, payload, sizeof(header));
+	header.flags = 0;
+	len -= sizeof(header);
+
+	/* catch remaining fragmented packets */
+	if (fastboot_data - (char *)ip_header + len > tot_len) {
+		fastboot_send(fbn, header, "can't reassemble fragmented frames");
+		return;
+	}
+	/* catch too large packets */
+	if (len > PACKET_SIZE) {
+		fastboot_send(fbn, header, "packet too large");
+		return;
+	}
+
+	memcpy(fbn->net_con->et->et_dest, eth_header->et_src, ETH_ALEN);
+	net_copy_ip(&fbn->net_con->ip->daddr, &ip_header->saddr);
+	fbn->net_con->udp->uh_dport = udp_header->uh_sport;
+
+	switch (header.id) {
+	case FASTBOOT_QUERY:
+		fastboot_send(fbn, header, NULL);
+		break;
+	case FASTBOOT_INIT:
+		if (ntohs(header.seq) != fbn->sequence_number) {
+			fastboot_check_retransmit(fbn, header);
+			break;
+		}
+		fbn->host_addr = net_read_ip(&ip_header->saddr);
+		fbn->host_port = udp_header->uh_sport;
+		memcpy(fbn->host_mac, eth_header->et_src, ETH_ALEN);
+		fbn->reinit = true;
+		if (fbn->active_download) {
+			/*
+			 * it is safe to call
+			 * fastboot_download_finished here
+			 * because reinit is true
+			 */
+			fastboot_download_finished(&fbn->fastboot);
+			fbn->active_download = false;
+		}
+		fastboot_send(fbn, header, NULL);
+		break;
+	case FASTBOOT_FASTBOOT:
+		if (!is_current_connection(fbn))
+			break;
+		memcpy(fbn->host_mac, eth_header->et_src, ETH_ALEN);
+		if (ntohs(header.seq) == fbn->sequence_number)
+			fastboot_handle_type_fastboot(fbn, header,
+						      fastboot_data, len);
+		else
+			fastboot_check_retransmit(fbn, header);
+		break;
+	default:
+		fastboot_send(fbn, header, "unknown packet type");
+		break;
+	}
+}
+
+static void fastboot_poll(struct poller_struct *poller)
+{
+	struct fastboot_net *fbn = container_of(poller, struct fastboot_net,
+					       poller);
+
+	net_poll();
+	if (!fbn->command[0])
+		return;
+
+	fbn->reinit = false;
+	fastboot_tx_print(&fbn->fastboot, FASTBOOT_MSG_NONE, "");
+	fastboot_exec_cmd(&fbn->fastboot, fbn->command);
+	fbn->command[0] = 0;
+
+	if (fbn->active_download) {
+		while (fbn->active_download)
+			net_poll();
+		if (!fbn->reinit)
+			fastboot_download_finished(&fbn->fastboot);
+	}
+}
+
+void fastboot_net_free(struct fastboot_net *fbn)
+{
+	fastboot_generic_close(&fbn->fastboot);
+	poller_unregister(&fbn->poller);
+	net_unregister(fbn->net_con);
+	fastboot_generic_free(&fbn->fastboot);
+	free(fbn);
+}
+
+struct fastboot_net *fastboot_net_init(struct fastboot_opts *opts)
+{
+	struct fastboot_net *fbn;
+	int ret;
+
+	fbn = xzalloc(sizeof(*fbn));
+	INIT_LIST_HEAD(&fbn->fastboot.variables);
+	fbn->fastboot.write = fastboot_write_net;
+	fbn->fastboot.start_download = fastboot_start_download_net;
+
+	if (opts) {
+		fbn->fastboot.files = opts->files;
+		fbn->fastboot.cmd_exec = opts->cmd_exec;
+		fbn->fastboot.cmd_flash = opts->cmd_flash;
+		ret = fastboot_generic_init(&fbn->fastboot, opts->export_bbu);
+	} else {
+		const char *fastboot_files = getenv("nv.fastboot.files");
+
+		fbn->fastboot.files = file_list_parse(fastboot_files);
+		ret = fastboot_generic_init(&fbn->fastboot, false);
+	}
+	if (ret)
+		goto fail_generic_init;
+
+	fbn->net_con = net_udp_new(IP_BROADCAST, FASTBOOT_PORT,
+				    fastboot_handler, fbn);
+	if (IS_ERR(fbn->net_con)) {
+		ret = PTR_ERR(fbn->net_con);
+		goto fail_net_con;
+	}
+	net_udp_bind(fbn->net_con, FASTBOOT_PORT);
+
+	fbn->poller.func = fastboot_poll;
+	ret = poller_register(&fbn->poller);
+	if (ret)
+		goto fail_poller;
+
+	return fbn;
+
+fail_poller:
+	net_unregister(fbn->net_con);
+fail_net_con:
+	fastboot_generic_free(&fbn->fastboot);
+fail_generic_init:
+	free(fbn);
+	return ERR_PTR(ret);
+}
+
+#ifdef CONFIG_FASTBOOT_NET_ON_BOOT
+static struct fastboot_net *fastboot_net_obj;
+
+static int fastboot_on_boot(void)
+{
+	struct fastboot_net *fbn;
+
+	ifup_all(0);
+	fbn = fastboot_net_init(NULL);
+
+	if (IS_ERR(fbn))
+		return PTR_ERR(fbn);
+
+	fastboot_net_obj = fbn;
+	return 0;
+}
+
+static void fastboot_net_exit(void)
+{
+	if (fastboot_net_obj)
+		fastboot_net_free(fastboot_net_obj);
+}
+
+postenvironment_initcall(fastboot_on_boot);
+predevshutdown_exitcall(fastboot_net_exit);
+#endif
-- 
2.17.1


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