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Handle incomplete packets

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spdfrk1 2014-07-15 01:05:50 +02:00 • committed by Jaroslav Kysela
parent a558c9e228
commit 0d73f421b1
1 changed files with 26 additions and 25 deletions
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51
src/descrambler/libaesdec/libaesdec.c Normal file → Executable file
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@ -36,12 +36,11 @@ void aes_set_control_words(void *keys, const unsigned char *ev,
}
//-----key structure
void *aes_get_key_struct(void) {
struct aes_keys_t *keys = (struct aes_keys_t *) malloc(
sizeof(struct aes_keys_t));
if (keys) {
static const unsigned char pk[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
static const unsigned char pk[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
aes_set_control_words(keys, pk, pk);
}
return keys;
@ -52,38 +51,40 @@ void aes_free_key_struct(void *keys) {
}
//----- decrypt
void aes_decrypt_packet(void *keys, unsigned char *packet) {
unsigned char *pkt;
unsigned char ev_od = 0;
int xc0, len, offset, n;
int xc0, offset, n;
int len;
//int residue;
pkt = packet;
AES_KEY k;
// TODO check all flags
xc0 = pkt[3] & 0xc0;
if (xc0 == 0x00) {//skip clear pkt
return;
}
if (xc0 == 0x40) { //skip reserved pkt
return;
}
xc0 = pkt[3] & 0xc0;
if (xc0 == 0x00) {//skip clear pkt
return;
}
if (xc0 == 0x40) { //skip reserved pkt
return;
}
if (xc0 == 0x80 || xc0 == 0xc0) { // encrypted
ev_od = (xc0 & 0x40) >> 6; // 0 even, 1 odd
pkt[3] &= 0x3f; // consider it decrypted now
if (pkt[3] & 0x20) { // incomplete packet
offset = 4 + pkt[4] + 1;
len = 188 - offset;
n = len >> 3;
//residue = len - (n << 3);
if (n == 0) { // decrypted==encrypted!
//DBG(fprintf(stderr,"DECRYPTED MINI!\n"));
return; // this doesn't need more processing
}
return; // TODO Handle incomplete packets?
if (pkt[3] & 0x20) { // incomplete packet TODO Check this
offset = 4 + pkt[4] + 1;
len = 188 - offset;
n = len >> 3;
//residue = len - (n << 3);
if (n == 0) { // decrypted==encrypted!
//DBG(fprintf(stderr,"DECRYPTED MINI!\n"));
return; // this doesn't need more processing
}
}
else {
len = 184;
offset = 4;
//residue = 0;
}
}
else {
@ -98,7 +99,7 @@ void aes_decrypt_packet(void *keys, unsigned char *packet) {
// TODO room for improvement?
int i;
for (i = 4; i <= 164; i += 16) {
for (i = offset; i <= (len - 16); i += 16) {
AES_ecb_encrypt(pkt + i, pkt + i, &k, AES_DECRYPT);
}
return;