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https://github.com/vgmstream/vgmstream.git
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128 lines
3.8 KiB
C
128 lines
3.8 KiB
C
#ifndef _NUS3BANK_STREAMFILE_H_
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#define _NUS3BANK_STREAMFILE_H_
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#include "../streamfile.h"
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static uint32_t swap_endian32(uint32_t v) {
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return ((v & 0xff000000) >> 24u) |
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((v & 0x00ff0000) >> 8u) |
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((v & 0x0000ff00) << 8u) |
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((v & 0x000000ff) << 24u);
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}
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#define KEY_MAX_SIZE 0x1000
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typedef struct {
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uint8_t key[KEY_MAX_SIZE];
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int key_len;
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} io_data_t;
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static size_t io_read(STREAMFILE *sf, uint8_t *dest, off_t offset, size_t length, io_data_t *data) {
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int i;
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size_t bytes = read_streamfile(dest, offset, length, sf);
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/* decrypt data (xor) */
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if (offset < data->key_len) {
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for (i = 0; i < bytes; i++) {
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if (offset + i < data->key_len)
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dest[i] ^= data->key[offset + i];
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}
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}
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return bytes;
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}
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/* decrypts RIFF streams in NUS3BANK */
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static STREAMFILE* setup_nus3bank_streamfile(STREAMFILE *sf, off_t start) {
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STREAMFILE *new_sf = NULL;
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io_data_t io_data = {0};
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/* setup key */
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{
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uint32_t base_key, chunk_key;
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uint8_t buf[KEY_MAX_SIZE];
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uint32_t chunk_type, chunk_size;
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int pos, data_pos, bytes;
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/* Header is XORed with a base key and a derived chunk type/size key, while chunk data is XORed with
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* unencrypted data itself, so we need to find where "data" starts then do another pass to properly set key.
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* Original code handles RIFF's "data" and also BNSF's "sdat" too, encrypted BNSF aren't known though. */
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bytes = read_streamfile(buf, start, sizeof(buf), sf);
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if (bytes < 0x800) goto fail; /* files of 1 XMA block do exist, but not less */
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base_key = 0x0763E951;
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chunk_type = get_u32be(buf + 0x00) ^ base_key;
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chunk_size = get_u32be(buf + 0x04) ^ base_key;
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if (chunk_type != 0x52494646) /* "RIFF" */
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goto fail;
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chunk_key = base_key ^ (((chunk_size >> 16u) & 0x0000FFFF) | ((chunk_size << 16u) & 0xFFFF0000)); /* ROTr 16 size */
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/* find "data" */
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pos = 0x0c;
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data_pos = 0;
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while(pos < sizeof(buf)) {
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chunk_type = get_u32be(buf + pos + 0x00) ^ chunk_key;
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chunk_size = get_u32be(buf + pos + 0x04) ^ chunk_key;
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chunk_size = swap_endian32(chunk_size);
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pos += 0x08;
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if (chunk_type == 0x64617461) { /* "data" */
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data_pos = pos;
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break;
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}
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if (pos + chunk_size > sizeof(buf) - 0x08) {
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VGM_LOG("NUS3 SF: header too big\n");
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goto fail; /* max around 0x400 */
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}
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pos += chunk_size;
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}
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/* setup key */
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put_u32be(io_data.key + 0x00, base_key);
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put_u32be(io_data.key + 0x04, base_key);
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put_u32be(io_data.key + 0x08, chunk_key);
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pos = 0x0c; /* after WAVE */
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while (pos < data_pos) {
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chunk_type = get_u32be(buf + pos + 0x00) ^ chunk_key;
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chunk_size = get_u32be(buf + pos + 0x04) ^ chunk_key;
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chunk_size = swap_endian32(chunk_size);
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put_u32be(io_data.key + pos + 0x00, chunk_key);
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put_u32be(io_data.key + pos + 0x04, chunk_key);
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pos += 0x08;
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if (pos >= data_pos)
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break;
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/* buf must contain data of at least chunk_size */
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if (data_pos + chunk_size >= sizeof(buf)) {
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VGM_LOG("NUS3 SF: chunk too big\n");
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goto fail;
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}
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memcpy(io_data.key + pos, buf + data_pos, chunk_size);
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pos += chunk_size;
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}
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io_data.key_len = data_pos;
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}
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new_sf = open_wrap_streamfile(sf);
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new_sf = open_io_streamfile(new_sf, &io_data, sizeof(io_data_t), io_read, NULL);
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return new_sf;
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fail:
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close_streamfile(sf);
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return NULL;
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}
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#endif /* _NUS3BANK_STREAMFILE_H_ */
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