//-----------------------------------------------------------------------------
// Copyright (C) 2010 Hector Martin "marcan" <marcan@marcansoft.com>
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// ELF file flasher
//-----------------------------------------------------------------------------

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "proxmark3.h"
#include "sleep.h"
#include "flash.h"
#include "elf.h"
#include "proxendian.h"
#include "usb_cmd.h"

void SendCommand(UsbCommand* txcmd);
void ReceiveCommand(UsbCommand* rxcmd);
void CloseProxmark();
int OpenProxmark(size_t i);

// FIXME: what the fuckity fuck
unsigned int current_command = CMD_UNKNOWN;

#define FLASH_START            0x100000
#define FLASH_SIZE             (256*1024)
#define FLASH_END              (FLASH_START + FLASH_SIZE)
#define BOOTLOADER_SIZE        0x2000
#define BOOTLOADER_END         (FLASH_START + BOOTLOADER_SIZE)

#define BLOCK_SIZE             0x200

static const uint8_t elf_ident[] = {
	0x7f, 'E', 'L', 'F',
	ELFCLASS32,
	ELFDATA2LSB,
	EV_CURRENT
};

// Turn PHDRs into flasher segments, checking for PHDR sanity and merging adjacent
// unaligned segments if needed
static int build_segs_from_phdrs(flash_file_t *ctx, FILE *fd, Elf32_Phdr *phdrs, int num_phdrs)
{
	Elf32_Phdr *phdr = phdrs;
	flash_seg_t *seg;
	uint32_t last_end = 0;

	ctx->segments = malloc(sizeof(flash_seg_t) * num_phdrs);
	if (!ctx->segments) {
		fprintf(stderr, "Out of memory\n");
		return -1;
	}
	ctx->num_segs = 0;
	seg = ctx->segments;

	fprintf(stderr, "Loading usable ELF segments:\n");
	for (int i = 0; i < num_phdrs; i++) {
		if (le32(phdr->p_type) != PT_LOAD) {
			phdr++;
			continue;
		}
		uint32_t vaddr = le32(phdr->p_vaddr);
		uint32_t paddr = le32(phdr->p_paddr);
		uint32_t filesz = le32(phdr->p_filesz);
		uint32_t memsz = le32(phdr->p_memsz);
		uint32_t offset = le32(phdr->p_offset);
		uint32_t flags = le32(phdr->p_flags);
		if (!filesz) {
			phdr++;
			continue;
		}
		fprintf(stderr, "%d: V 0x%08x P 0x%08x (0x%08x->0x%08x) [%c%c%c] @0x%x\n",
		        i, vaddr, paddr, filesz, memsz,
		        flags & PF_R ? 'R' : ' ',
		        flags & PF_W ? 'W' : ' ',
		        flags & PF_X ? 'X' : ' ',
		        offset);
		if (filesz != memsz) {
			fprintf(stderr, "Error: PHDR file size does not equal memory size\n"
			                "(DATA+BSS PHDRs do not make sense on ROM platforms!)\n");
			return -1;
		}
		if (paddr < last_end) {
			fprintf(stderr, "Error: PHDRs not sorted or overlap\n");
			return -1;
		}
		if (paddr < FLASH_START || (paddr+filesz) > FLASH_END) {
			fprintf(stderr, "Error: PHDR is not contained in Flash\n");
			return -1;
		}
		if (vaddr >= FLASH_START && vaddr < FLASH_END && (flags & PF_W)) {
			fprintf(stderr, "Error: Flash VMA segment is writable\n");
			return -1;
		}

		uint8_t *data;
		// make extra space if we need to move the data forward
		data = malloc(filesz + BLOCK_SIZE);
		if (!data) {
			fprintf(stderr, "Out of memory\n");
			return -1;
		}
		if (fseek(fd, offset, SEEK_SET) < 0 || fread(data, 1, filesz, fd) != filesz) {
			fprintf(stderr, "Error while reading PHDR payload\n");
			free(data);
			return -1;
		}

		uint32_t block_offset = paddr & (BLOCK_SIZE-1);
		if (block_offset) {
			if (ctx->num_segs) {
				flash_seg_t *prev_seg = seg - 1;
				uint32_t this_end = paddr + filesz;
				uint32_t this_firstblock = paddr & ~(BLOCK_SIZE-1);
				uint32_t prev_lastblock = (last_end - 1) & ~(BLOCK_SIZE-1);

				if (this_firstblock == prev_lastblock) {
					uint32_t new_length = this_end - prev_seg->start;
					uint32_t this_offset = paddr - prev_seg->start;
					uint32_t hole = this_offset - prev_seg->length;
					uint8_t *new_data = malloc(new_length);
					if (!new_data) {
						fprintf(stderr, "Out of memory\n");
						free(data);
						return -1;
					}
					memset(new_data, 0xff, new_length);
					memcpy(new_data, prev_seg->data, prev_seg->length);
					memcpy(new_data + this_offset, data, filesz);
					fprintf(stderr, "Note: Extending previous segment from 0x%x to 0x%x bytes\n",
					        prev_seg->length, new_length);
					if (hole)
						fprintf(stderr, "Note: 0x%x-byte hole created\n", hole);
					free(data);
					free(prev_seg->data);
					prev_seg->data = new_data;
					prev_seg->length = new_length;
					last_end = this_end;
					phdr++;
					continue;
				}
			}
			fprintf(stderr, "Warning: segment does not begin on a block boundary, will pad\n");
			memmove(data + block_offset, data, filesz);
			memset(data, 0xFF, block_offset);
			filesz += block_offset;
			paddr -= block_offset;
		}

		seg->data = data;
		seg->start = paddr;
		seg->length = filesz;
		seg++;
		ctx->num_segs++;

		last_end = paddr + filesz;
		phdr++;
	}
	return 0;
}

// Sanity check segments and check for bootloader writes
static int check_segs(flash_file_t *ctx, int can_write_bl) {
	for (int i = 0; i < ctx->num_segs; i++) {
		flash_seg_t *seg = &ctx->segments[i];

		if (seg->start & (BLOCK_SIZE-1)) {
			fprintf(stderr, "Error: Segment is not aligned\n");
			return -1;
		}
		if (seg->start < FLASH_START) {
			fprintf(stderr, "Error: Segment is outside of flash bounds\n");
			return -1;
		}
		if (seg->start + seg->length > FLASH_END) {
			fprintf(stderr, "Error: Segment is outside of flash bounds\n");
			return -1;
		}
		if (!can_write_bl && seg->start < BOOTLOADER_END) {
			fprintf(stderr, "Attempted to write bootloader but bootloader writes are not enabled\n");
			return -1;
		}
	}
	return 0;
}

// Load an ELF file and prepare it for flashing
int flash_load(flash_file_t *ctx, const char *name, int can_write_bl)
{
	FILE *fd = NULL;
	Elf32_Ehdr ehdr;
	Elf32_Phdr *phdrs = NULL;
	int num_phdrs;
	int res;

	fd = fopen(name, "rb");
	if (!fd) {
		fprintf(stderr, "Could not open file '%s': ", name);
		perror(NULL);
		goto fail;
	}

	fprintf(stderr, "Loading ELF file '%s'...\n", name);

	if (fread(&ehdr, sizeof(ehdr), 1, fd) != 1) {
		fprintf(stderr, "Error while reading ELF file header\n");
		goto fail;
	}
	if (memcmp(ehdr.e_ident, elf_ident, sizeof(elf_ident))
		|| le32(ehdr.e_version) != 1)
	{
		fprintf(stderr, "Not an ELF file or wrong ELF type\n");
		goto fail;
	}
	if (le16(ehdr.e_type) != ET_EXEC) {
		fprintf(stderr, "ELF is not executable\n");
		goto fail;
	}
	if (le16(ehdr.e_machine) != EM_ARM) {
		fprintf(stderr, "Wrong ELF architecture\n");
		goto fail;
	}
	if (!ehdr.e_phnum || !ehdr.e_phoff) {
		fprintf(stderr, "ELF has no PHDRs\n");
		goto fail;
	}
	if (le16(ehdr.e_phentsize) != sizeof(Elf32_Phdr)) {
		// could be a structure padding issue...
		fprintf(stderr, "Either the ELF file or this code is made of fail\n");
		goto fail;
	}
	num_phdrs = le16(ehdr.e_phnum);

	phdrs = malloc(le16(ehdr.e_phnum) * sizeof(Elf32_Phdr));
	if (!phdrs) {
		fprintf(stderr, "Out of memory\n");
		goto fail;
	}
	if (fseek(fd, le32(ehdr.e_phoff), SEEK_SET) < 0) {
		fprintf(stderr, "Error while reading ELF PHDRs\n");
		goto fail;
	}
	if (fread(phdrs, sizeof(Elf32_Phdr), num_phdrs, fd) != num_phdrs) {
		fprintf(stderr, "Error while reading ELF PHDRs\n");
		goto fail;
	}

	res = build_segs_from_phdrs(ctx, fd, phdrs, num_phdrs);
	if (res < 0)
		goto fail;
	res = check_segs(ctx, can_write_bl);
	if (res < 0)
		goto fail;

	free(phdrs);
	fclose(fd);
	ctx->filename = name;
	return 0;

fail:
	if (phdrs)
		free(phdrs);
	if (fd)
		fclose(fd);
	flash_free(ctx);
	return -1;
}

// Get the state of the proxmark, backwards compatible
static int get_proxmark_state(uint32_t *state)
{
	UsbCommand c;
	c.cmd = CMD_DEVICE_INFO;
  SendCommand(&c);
	UsbCommand resp;
	ReceiveCommand(&resp);

	// Three outcomes:
	// 1. The old bootrom code will ignore CMD_DEVICE_INFO, but respond with an ACK
	// 2. The old os code will respond with CMD_DEBUG_PRINT_STRING and "unknown command"
	// 3. The new bootrom and os codes will respond with CMD_DEVICE_INFO and flags

	switch (resp.cmd) {
		case CMD_ACK:
			*state = DEVICE_INFO_FLAG_CURRENT_MODE_BOOTROM;
			break;
		case CMD_DEBUG_PRINT_STRING:
			*state = DEVICE_INFO_FLAG_CURRENT_MODE_OS;
			break;
		case CMD_DEVICE_INFO:
			*state = resp.arg[0];
			break;
		default:
			fprintf(stderr, "Error: Couldn't get proxmark state, bad response type: 0x%04"llx"\n", resp.cmd);
			return -1;
			break;
	}

	return 0;
}

// Enter the bootloader to be able to start flashing
static int enter_bootloader(char *serial_port_name)
{
	uint32_t state;

	if (get_proxmark_state(&state) < 0)
		return -1;

	if (state & DEVICE_INFO_FLAG_CURRENT_MODE_BOOTROM) {
		/* Already in flash state, we're done. */
		return 0;
	}

	if (state & DEVICE_INFO_FLAG_CURRENT_MODE_OS) {
		fprintf(stderr,"Entering bootloader...\n");
		UsbCommand c;
		memset(&c, 0, sizeof (c));

		if ((state & DEVICE_INFO_FLAG_BOOTROM_PRESENT)
			&& (state & DEVICE_INFO_FLAG_OSIMAGE_PRESENT))
		{
			// New style handover: Send CMD_START_FLASH, which will reset the board
			// and enter the bootrom on the next boot.
			c.cmd = CMD_START_FLASH;
			SendCommand(&c);
			fprintf(stderr,"(Press and release the button only to abort)\n");
		} else {
			// Old style handover: Ask the user to press the button, then reset the board
			c.cmd = CMD_HARDWARE_RESET;
			SendCommand(&c);
			fprintf(stderr,"Press and hold down button NOW if your bootloader requires it.\n");
		}
    msleep(100);
		CloseProxmark();

		fprintf(stderr,"Waiting for Proxmark to reappear on %s",serial_port_name);
    do {
			sleep(1);
			fprintf(stderr, ".");
		} while (!OpenProxmark(0));
		fprintf(stderr," Found.\n");

		return 0;
	}

	fprintf(stderr, "Error: Unknown Proxmark mode\n");
	return -1;
}

static int wait_for_ack(void)
{
  UsbCommand ack;
	ReceiveCommand(&ack);
	if (ack.cmd != CMD_ACK) {
		printf("Error: Unexpected reply 0x%04"llx" (expected ACK)\n", ack.cmd);
		return -1;
	}
	return 0;
}

// Go into flashing mode
int flash_start_flashing(int enable_bl_writes,char *serial_port_name)
{
	uint32_t state;

	if (enter_bootloader(serial_port_name) < 0)
		return -1;

	if (get_proxmark_state(&state) < 0)
		return -1;

	if (state & DEVICE_INFO_FLAG_UNDERSTANDS_START_FLASH) {
		// This command is stupid. Why the heck does it care which area we're
		// flashing, as long as it's not the bootloader area? The mind boggles.
		UsbCommand c = {CMD_START_FLASH};

		if (enable_bl_writes) {
			c.arg[0] = FLASH_START;
			c.arg[1] = FLASH_END;
			c.arg[2] = START_FLASH_MAGIC;
		} else {
			c.arg[0] = BOOTLOADER_END;
			c.arg[1] = FLASH_END;
			c.arg[2] = 0;
		}
		SendCommand(&c);
		return wait_for_ack();
	} else {
		fprintf(stderr, "Note: Your bootloader does not understand the new START_FLASH command\n");
		fprintf(stderr, "      It is recommended that you update your bootloader\n\n");
	}

	return 0;
}

static int write_block(uint32_t address, uint8_t *data, uint32_t length)
{
	uint8_t block_buf[BLOCK_SIZE];

	memset(block_buf, 0xFF, BLOCK_SIZE);
	memcpy(block_buf, data, length);
  UsbCommand c;
	c.cmd = CMD_FINISH_WRITE;
	c.arg[0] = address;
	memcpy(c.d.asBytes, block_buf, length);
  SendCommand(&c);
  return wait_for_ack();
}

// Write a file's segments to Flash
int flash_write(flash_file_t *ctx)
{
	fprintf(stderr, "Writing segments for file: %s\n", ctx->filename);
	for (int i = 0; i < ctx->num_segs; i++) {
		flash_seg_t *seg = &ctx->segments[i];

		uint32_t length = seg->length;
		uint32_t blocks = (length + BLOCK_SIZE - 1) / BLOCK_SIZE;
		uint32_t end = seg->start + length;

		fprintf(stderr, " 0x%08x..0x%08x [0x%x / %d blocks]",
		        seg->start, end - 1, length, blocks);

		int block = 0;
		uint8_t *data = seg->data;
		uint32_t baddr = seg->start;

		while (length) {
			uint32_t block_size = length;
			if (block_size > BLOCK_SIZE)
				block_size = BLOCK_SIZE;

			if (write_block(baddr, data, block_size) < 0) {
				fprintf(stderr, " ERROR\n");
				fprintf(stderr, "Error writing block %d of %d\n", block, blocks);
				return -1;
			}

			data += block_size;
			baddr += block_size;
			length -= block_size;
			block++;
			fprintf(stderr, ".");
		}
		fprintf(stderr, " OK\n");
	}
	return 0;
}

// free a file context
void flash_free(flash_file_t *ctx)
{
	if (!ctx)
		return;
	if (ctx->segments) {
		for (int i = 0; i < ctx->num_segs; i++)
			free(ctx->segments[i].data);
		free(ctx->segments);
		ctx->segments = NULL;
		ctx->num_segs = 0;
	}
}

// just reset the unit
int flash_stop_flashing(void) {
	UsbCommand c = {CMD_HARDWARE_RESET};
  SendCommand(&c);
  msleep(100);
  return 0;
}
