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raspbootin.c
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raspbootin.c
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/* Copyright (C) 2013 by John Cronin <jncronin@tysos.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/* This is a file system based upon the raspbootin bootloader by mrvn:
https://github.com/mrvn/raspbootin
It is a protocol which supports transfer of a kernel over a serial link.
It supports two versions of the protocol, the first defined as per the
above link and a version two which is defined here.
All commands are initiated by the client, and responses are returned
by the server.
Definitions:
<byte> A single byte
<lsb16> A 16-bit number transmitted in LSB format
<lsb32> A 32-bit number transmitted in LSB format
<msb32> A 32-bit number transmitted in MSB format
<string> A string transmitted in the format:
<lsb16 length><byte 0><byte 1>...<byte n>
Note not null-terminated and string is in UTF-8 format
<magic> The four bytes <byte 0x31><byte 0x41><byte 0x59><byte 0x27>
<msg_length> The length of the response sent as a <lsb32> - this is
the length minus the length of <magic> and <crc>
<crc> A CRC-32 checksum of the command or response transmitted as
a <msb32>. If this fails the command should be re-sent.
The particular CRC polynomial is 0x04C11DB7 as per
IEEE 802.3
<dir_entry> A directory entry in the form:
<lsb32 byte_size><lsb32 user_id><lsb32 group_id>
<lsb32 properties><string name>
properties is a bit-mask of file/directory properties
as defined later.
Commands:
All commands take the form: <byte \003><byte \003><byte cmd_id><options>
Compatibility:
RBTIN_V1 Required for raspbootin v1
RBTIN_V2_REQ Required for raspbootin v2
RBTIN_V2_SPEC Optional for raspbootin v2 (support is defined
in the response to cmd_id 0)
Error codes:
0 Success (returned in error response to cmd_id 1 if
there are no entries within the directory)
-1 Path not found
-2 EOF
-3 CRC error in request
File/directory properties:
These are defined as per the st_mode field in the man page to lstat(2).
In particular, S_IFDIR = 0x40000 is set if the entry is a directory.
Command list:
cmd_id Compatibility Function
0 RBTIN_V2_REQ ID and query functionality
<options> is <crc>
Returns <magic><msg_length><lsb32 error_code>
<lsb32 functions><crc> if the server is a valid v2
server.
Functions is a bit-mask specifying support for each
function number (1 to support). For example, if a
server supports functions 0-4 inclusive, this will
be 11111b = 0x1f.
1 RBTIN_V2_SPEC Read directory entries
<options> is <string dir_name><crc>
Returns the entries within the specified directory
Returns:
<magic><msg_length><lsb32 error_code><lsb32 0>
<crc>
- if no entries or error
<magic><msg_length><lsb32 0><lsb32 entry_count>
<byte 0><dir_entry 0><dir_entry 1>...
<dir_entry n><crc>
- if success return a list of the entries
- the <byte 0> defines the dir_entry
version and can be changed in future
versions.
2 RBTIN_V2_SPEC Read part of a file
<options> is <string file_name><lsb32 start>
<lsb32 length><crc>
Reads the part of a file starting at address start
and of length 'length'
Returns:
<magic><msg_length><lsb32 error_code><lsb32 0>
<crc>
- if error
<magic><msg_length><lsb32 0><lsb32 bytes_read>
<byte 0><byte 1>...<byte n><crc>
- if success
3 RBTIN_V1 Send the default kernel (all of it)
<options> is empty
Returns:
<lsb32 length><byte 0><byte 1>...<byte n>
4 RBTIN_V2_SPEC Display a string on the server console
<options> is <string message><crc>
Returns:
<magic><msg_length><lsb32 error_code><crc>
*/
/* Specifics of the rpi_boot implementation:
During init, we try and communicate with the server by sending cmd_id 0.
If a valid response is returned we cache the result and continue.
If not, we still assume a server is present but that it is v1 (and
cache supported functionality as 0x8 - only cmd_id 3 supported).
During directory enumeration/file loading, if a v2 response is cached
we use that to try and load the file via the v2 functions.
If v1, and the root directory is enumerated, we return a single member:
/raspbootin of type file and unknown length
If v1, and a directory other than the root directory is enumerated, we
return error code ENOENT
If v1, and the file /raspbootin is requested, we send cmd_id 3 and save
the appropriate section to the buffer (and discard the rest)
If v1, and any other file is requested, we return error code ENOENT
*/
#ifndef ENABLE_SERIAL
#error Raspbootin support requires ENABLE_SERIAL in config.h
#endif
#include <string.h>
#include "fs.h"
#include "output.h"
#include "uart.h"
#include "crc32.h"
#include "block.h"
#include "raspbootin.h"
#define UART_TIMEOUT 10000
#define READDIR_BUF_LEN 0x1000
#define MAX_RETRIES 3
#define CLIENT_CAPABILITIES 0x1f
#define BYTE(num, idx) (((num) >> ((idx) * 8)) & 0xff)
#ifdef RASPBOOTIN_DEBUG
#define CHECK(resp, floc) if((resp) == -1) { ret = TIMEOUT; fail_loc = floc; goto cleanup; }
#else
#define CHECK(resp, floc) if((resp) == -1) { ret = TIMEOUT; goto cleanup; }
#endif
static uint32_t server_capabilities = 9; // assume server can interpret
// cmds 0 and 3
static uint32_t client_capabilities = CLIENT_CAPABILITIES;
static char raspbootin_name[] = "raspbootin";
static struct dirent *raspbootin_read_directory(struct fs *fs, char **name);
static FILE *raspbootin_fopen(struct fs *fs, struct dirent *path, const char *mode);
static size_t raspbootin_fread(struct fs *fs, void *ptr, size_t size, size_t nmemb, FILE *stream);
static int raspbootin_fclose(struct fs *fs, FILE *fp);
static int send_message(int cmd_id, void *send_buf, size_t send_buf_len,
void *recv_buf, size_t recv_buf_len);
static int read_lsb32(uint32_t *val, useconds_t timeout)
{
uint32_t ret = 0;
for(int i = 0; i < 4; i++)
{
int rbuf = uart_getc_timeout(timeout);
if(rbuf == -1)
return -1;
uint32_t v = (uint32_t)rbuf & 0xff;
ret |= (v << (i * 8));
}
*val = ret;
return 0;
}
static int send_message_int(int cmd_id, void *send_buf, size_t send_buf_len,
void *recv_buf, size_t recv_buf_len)
{
// Send a message (v2 messages only)
#ifdef RASPBOOTIN_DEBUG
printf("RASPBOOTIN: sending cmd %i\n");
int fail_loc = 0;
#endif
// Check capabilities
if((cmd_id < 0) || (cmd_id > 31))
{
printf("RASPBOOTIN: invalid cmd number %i\n");
return INVALID_CMD;
}
if(cmd_id == 3)
{
printf("RASPBOOTIN: cannot use send_message_int to send cmd 3\n");
return INVALID_CMD;
}
uint32_t msg_capabilities = (1 << cmd_id);
if(!(client_capabilities & msg_capabilities))
{
printf("RASPBOOTIN: client does not support cmd %i\n");
return UNSUPPORTED_CMD;
}
if(!(server_capabilities & msg_capabilities))
{
printf("RASPBOOTIN: server does not support cmd %i\n");
return UNSUPPORTED_CMD;
}
// The crc of the request is calculated from 'options'
uint32_t crc = crc32(send_buf, send_buf_len);
// Disable debug output on the uart
rpi_boot_output_state ostate = output_get_state();
output_disable_uart();
// Clear the receive buffer
while(uart_getc_timeout(1000) != -1);
// Send the message
uart_putc('\003');
uart_putc('\003');
uart_putc(cmd_id);
uint8_t *send_p = (uint8_t *)send_buf;
while(send_buf_len--)
uart_putc(*send_p++);
uart_putc(BYTE(crc, 0));
uart_putc(BYTE(crc, 1));
uart_putc(BYTE(crc, 2));
uart_putc(BYTE(crc, 3));
// Wait for the response
usleep(2000);
// Begin reading response
int r_buf = 0;
int ret = 0;
// Read magic number
uint32_t magic = 0;
CHECK(read_lsb32(&magic, UART_TIMEOUT), 0);
if(magic != MAGIC)
{
#ifdef RASPBOOTIN_DEBUG
printf("RASPBOOTIN: invalid magic received: %08x (expecting %08x)\n", magic, MAGIC);
#endif
ret = INVALID_MAGIC;
goto cleanup;
}
// Read response length
uint32_t resp_length = 0;
CHECK(read_lsb32(&resp_length, UART_TIMEOUT), 1);
// Read error_code
uint32_t error_code = 0;
CHECK(read_lsb32(&error_code, UART_TIMEOUT), 2);
if(error_code != SUCCESS)
{
ret = error_code;
#ifdef RASPBOOTIN_DEBUG
fail_loc = 3;
#endif
goto cleanup;
}
// Read the data (maximum is whatever is greater - recv_buf_len
// or resp_length)
// Resp_length is length of the message minus magic and crc
// therefore it includes the length of resp_length and error_code
// which have already been read, therefore subtract 8
size_t data_to_read_to_buffer = (size_t)(resp_length - 8);
size_t data_to_discard = 0;
size_t data_to_pad = 0;
if(data_to_read_to_buffer > recv_buf_len)
{
data_to_read_to_buffer = recv_buf_len;
data_to_discard = data_to_read_to_buffer - recv_buf_len;
}
else if(recv_buf_len > data_to_read_to_buffer)
data_to_pad = recv_buf_len - data_to_read_to_buffer;
crc = crc32_start();
crc = crc32_append(crc, &magic, 4);
crc = crc32_append(crc, &resp_length, 4);
crc = crc32_append(crc, &error_code, 4);
int data_read = 0;
uint8_t *rptr = (uint8_t *)recv_buf;
while(data_to_read_to_buffer--)
{
r_buf = uart_getc_timeout(UART_TIMEOUT);
CHECK(r_buf, 4);
crc = crc32_append(crc, &r_buf, 1);
*rptr++ = r_buf;
data_read++;
}
while(data_to_discard--)
{
r_buf = uart_getc_timeout(UART_TIMEOUT);
CHECK(r_buf, 5);
crc = crc32_append(crc, &r_buf, 1);
}
while(data_to_pad--)
*rptr++ = 0;
crc = crc32_finish(crc);
// Read the response CRC
uint32_t resp_crc = 0;
CHECK(read_lsb32(&resp_crc, UART_TIMEOUT), 6);
if(resp_crc != crc)
{
ret = CRC_ERROR;
#ifdef RASPBOOTIN_DEBUG
fail_loc = 7;
#endif
goto cleanup;
}
cleanup:
if(ret == 0)
ret = data_read;
// Clear the uart buffer
while(uart_getc_timeout(1000) != -1);
// Re-enable uart debug output
output_restore_state(ostate);
#ifdef RASPBOOTIN_DEBUG
printf("RASPBOOTIN: send_message_int, returning %i (fail_loc %i)\n",
ret, fail_loc);
if(ret == CRC_ERROR)
{
printf("RASPBOOTIN: CRC error: read CRC %08x, expected %08x, magic %08x, resp_length %08x, error_code %08x\n",
resp_crc, crc, magic, resp_length, error_code);
}
#endif
return ret;
}
static int send_message(int cmd_id, void *send_buf, size_t send_buf_len,
void *recv_buf, size_t recv_buf_len)
{
// Send a message, retry on CRC failure
int retries = 0;
while(retries < MAX_RETRIES)
{
int ret = send_message_int(cmd_id, send_buf, send_buf_len,
recv_buf, recv_buf_len);
if(ret >= 0)
return ret;
if(ret != CRC_ERROR)
return ret;
retries++;
}
return CRC_ERROR;
}
int raspbootin_init(struct fs **fs)
{
// Try and communicate with a raspbootin server
uint32_t caps;
int ret = send_message(0, 0, 0, &caps, sizeof(uint32_t));
if(ret == sizeof(uint32_t))
{
printf("RASPBOOTIN: server contacted.\n");
server_capabilities = caps;
#ifdef RASPBOOTIN_DEBUG
printf("RASPBOOTIN: server capabilities: %08x\n", caps);
#endif
}
else
{
#ifdef RASPBOOTIN_DEBUG
printf("RASPBOOTIN: no server response to cmd 0 (ret %i)\n", ret);
#endif
server_capabilities = (1 << 3); // only support v1
}
// Build a block device structure
struct block_device *b_dev = (struct block_device *)malloc(sizeof(struct block_device));
memset(b_dev, 0, sizeof(struct block_device));
b_dev->device_name = raspbootin_name;
// Build a fs structure
struct fs *r_fs = (struct fs *)malloc(sizeof(struct fs));
memset(r_fs, 0, sizeof(struct fs));
r_fs->parent = b_dev;
r_fs->fs_name = raspbootin_name;
r_fs->fopen = raspbootin_fopen;
r_fs->fread = raspbootin_fread;
r_fs->fclose = raspbootin_fclose;
r_fs->read_directory = raspbootin_read_directory;
*fs = r_fs;
return 0;
}
static struct dirent *raspbootin_read_directory(struct fs *fs, char **name)
{
(void)fs;
// Join together the directory name
int dir_name_length = 0;
char **name_p = name;
while(*name_p)
{
dir_name_length += strlen(*name_p);
dir_name_length++;
name_p++;
}
dir_name_length++;
char *dir_name = (char *)malloc(dir_name_length);
name_p = name;
char *dir_name_p = dir_name;
while(*name_p)
{
strcpy(dir_name_p, *name_p);
dir_name_p += strlen(*name_p);
*dir_name_p++ = '/';
name_p++;
}
*dir_name_p = '\0';
// Resolve the root directory to an empty string
int is_root = 0;
if(strcmp(dir_name, "/"))
{
dir_name[0] = '\0';
is_root = 1;
}
// Create a string object of the correct size
// Send a request for the contents of this directory
if(server_capabilities & (1 << 1))
{
uint8_t *buf = (uint8_t *)malloc(READDIR_BUF_LEN);
int ret = send_message(1, dir_name, strlen(dir_name),
buf, READDIR_BUF_LEN);
(void)ret;
}
(void)is_root;
return (void *)0;
}
static FILE *raspbootin_fopen(struct fs *fs, struct dirent *path,
const char *mode)
{
(void)fs;
(void)path;
(void)mode;
return (void *)0;
}
static int raspbootin_fclose(struct fs *fs, FILE *fp)
{
(void)fs;
(void)fp;
return 0;
}
static size_t raspbootin_fread(struct fs *fs, void *ptr, size_t size,
size_t nmemb, FILE *stream)
{
(void)fs;
(void)ptr;
(void)size;
(void)nmemb;
(void)stream;
return 0;
}