- let mut payment_preimage = None;
- for i in 0..payments_sent {
- let mut payment_hash = [0; 32];
- payment_hash[0..8].copy_from_slice(&be64_to_array(i));
- let mut sha = Sha256::new();
- sha.input(&payment_hash);
- sha.result(&mut payment_hash);
- for i in 1..32 { payment_hash[i] = 0; }
- if payment_hash == payment {
- payment_hash = [0; 32];
- payment_hash[0..8].copy_from_slice(&be64_to_array(i));
- payment_preimage = Some(payment_hash);
- break;
- }
+ // SHA256 is defined as XOR of all input bytes placed in the first byte, and 0s
+ // for the remaining bytes. Thus, if not all remaining bytes are 0s we cannot
+ // fulfill this HTLC, but if they are, we can just take the first byte and
+ // place that anywhere in our preimage.
+ if &payment[1..] != &[0; 31] {
+ channelmanager.fail_htlc_backwards(&payment);
+ } else {
+ let mut payment_preimage = [0; 32];
+ payment_preimage[0] = payment[0];
+ channelmanager.claim_funds(payment_preimage);