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emrtd: Use memcmp for JPEG headers

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Ave 2020-12-23 23:08:34 +03:00
parent 27094b70eb
commit 9987ebf534
1 changed files with 6 additions and 4 deletions
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10
client/src/cmdhfemrtd.c
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@ -693,17 +693,19 @@ static bool emrtd_select_and_read(uint8_t *dataout, int *dataoutlen, const char
return true;
}
const uint8_t jpeg_header[4] = { 0xFF, 0xD8, 0xFF, 0xE0 };
const uint8_t jpeg2k_header[6] = { 0x00, 0x00, 0x00, 0x0C, 0x6A, 0x50 };
static int emrtd_dump_ef_dg2(uint8_t *file_contents, size_t file_length) {
int offset, datalen = 0;
// This is a hacky impl that just looks for the image header. I'll improve it eventually.
// based on mrpkey.py
// FF D8 FF E0 -> JPEG
// 00 00 00 0C 6A 50 -> JPEG 2000
// Note: Doing file_length - 6 to account for the longest data we're checking.
// Checks first byte before the rest to reduce overhead
for (offset = 0; offset < file_length - 6; offset++) {
if ((file_contents[offset] == 0xFF && file_contents[offset + 1] == 0xD8 && file_contents[offset + 2] == 0xFF && file_contents[offset + 3] == 0xE0) ||
(file_contents[offset] == 0x00 && file_contents[offset + 1] == 0x00 && file_contents[offset + 2] == 0x00 && file_contents[offset + 3] == 0x0C && file_contents[offset + 4] == 0x6A && file_contents[offset + 5] == 0x50)) {
if ((file_contents[offset] == 0xFF && memcmp(jpeg_header, file_contents + offset, 4) != 0) ||
(file_contents[offset] == 0x00 && memcmp(jpeg2k_header, file_contents + offset, 6) != 0)) {
datalen = file_length - offset;
break;
}