dump_config.c

//
//  dump_config.c
//  
//
//  Copyright (C) 2020 Thibaut VARÈNE - License: GPLv2 only
//

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>

#define BYTESWAP 1	// 1: enabled / 0: disabled


#define RB_MAGIC_HARD	(('H') | ('a' << 8) | ('r' << 16) | ('d' << 24))
#define RB_MAGIC_SOFT	(('S') | ('o' << 8) | ('f' << 16) | ('t' << 24))

#if BYTESWAP
static inline uint16_t bswap_16(uint16_t x)
{
	return (x >> 8) | (x << 8);
}
static inline uint32_t bswap_32(uint32_t x)
{
	return (bswap_16(x & 0xffff) << 16) | (bswap_16(x >> 16));
}
#else
static inline uint16_t bswap_16(uint16_t x)
{
	return x;
}
static inline uint32_t bswap_32(uint32_t x)
{
	return x;
}
#endif


void routerboot_tag_show_u32s(const uint8_t *pld, uint16_t pld_len)
{
	uint32_t *data;	// cpu-endian
	char buf[5];

	if (pld_len && (pld_len % sizeof(*data)))
		return;

	data = (uint32_t *)pld;

	do {
		memcpy(buf, data, sizeof(*data));
		buf[4] = '\0';
		printf("  0x%08x - %s\n", bswap_32(*data), buf);
		data++;
	} while ((pld_len -= sizeof(*data)));
}

int routerboot_tag_find(const uint8_t *bufhead, const size_t buflen, const uint16_t tag_id,
			uint16_t *pld_ofs, uint16_t *pld_len)
{
	const uint32_t *datum, *bufend;
	uint32_t node;
	uint16_t id, len;
	int ret;

	if (!bufhead)
		return -1;

	ret = -1;
	datum = (const uint32_t *)bufhead;
	bufend = (const uint32_t *)(bufhead + buflen);

	while (datum < bufend) {
		node = *datum++;
		node = bswap_32(node);

		/* Tag list ends with null node */
		if (!node)
			break;

		id = node & 0xFFFF;
		len = node >> 16;

		if (datum >= bufend)
			break;

		if (pld_ofs)
			*pld_ofs = (uint16_t)((uint8_t *)datum - bufhead);
		if (pld_len)
			*pld_len = len;

		if ((!tag_id) || (tag_id == id))
			printf("found tag 0x%02x, len: %d\n", id, len);

		if ((!tag_id && (len < 0x40)) || (tag_id == id))
			routerboot_tag_show_u32s((uint8_t *)datum, len);

		datum += len / sizeof(*datum);
	}

	return ret;
}

int main(int argc, char **argv)
{
	FILE *fp;
	size_t len = 0x1000;
	unsigned char buf[len], *p;
	uint32_t *data;
	uint16_t id;

	if ((argc < 2) || (argc > 3)) {
		printf("usage: %s <file> [tagid]\n", argv[0]);
		return -1;
	}

	printf("Byteswapping is %s.\n", (BYTESWAP) ? "enabled" : "disabled");

	fp = fopen(argv[1], "rb");
	len = fread(buf, 1, len, fp);
	fclose(fp);

	if (argc == 3)
		id = strtol(argv[2], NULL, 0);
	else
		id = 0;

	p = buf;
	data = (uint32_t *)p;

	if (bswap_32(*data) == RB_MAGIC_HARD) {
		printf("hard_config found.\n");
		p += 4;
		len -= 4;
	} else if (bswap_32(*data) == RB_MAGIC_SOFT) {
		printf("soft_config found.\n");
		p += 8;
		len -= 8;
	} else {
		printf("Magic not found!\n");
		return -1;
	}

	routerboot_tag_find(p, len, id, NULL, NULL);

	return 0;
}