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Clarify roles in failing HTLCs, implement most of it #13

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Merged
merged 2 commits into from
Mar 22, 2018
Merged

Clarify roles in failing HTLCs, implement most of it #13

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ac3bf5b
Fix length requirement in peer_handler msg decode
TheBlueMatt Mar 20, 2018
40ab09f
Clarify roles in failing HTLCs, impl it, support rebalances
TheBlueMatt Mar 20, 2018
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73 changes: 50 additions & 23 deletions src/ln/channel.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -782,15 +782,47 @@ impl Channel {
return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
}

//TODO: This is racy af, they may have pending messages in flight to us that will not have
//received this yet!
self.value_to_self_msat += htlc_amount_msat;

Ok(msgs::UpdateFulfillHTLC {
channel_id: self.channel_id(),
htlc_id: htlc_id,
payment_preimage: payment_preimage,
})
}

pub fn get_update_fail_htlc(&mut self, payment_hash: &[u8; 32], err_packet: msgs::OnionErrorPacket) -> Result<msgs::UpdateFailHTLC, HandleError> {
if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
return Err(HandleError{err: "Was asked to fail an HTLC when channel was not in an operational state", msg: None});
}

let mut htlc_id = 0;
let mut htlc_amount_msat = 0;
self.pending_htlcs.retain(|ref htlc| {
if !htlc.outbound && htlc.payment_hash == *payment_hash {
if htlc_id != 0 {
panic!("Duplicate HTLC payment_hash, you probably re-used payment preimages, NEVER DO THIS!");
}
htlc_id = htlc.htlc_id;
htlc_amount_msat += htlc.amount_msat;
false
} else { true }
});
if htlc_amount_msat == 0 {
return Err(HandleError{err: "Unable to find a pending HTLC which matched the given payment preimage", msg: None});
}

//TODO: This is racy af, they may have pending messages in flight to us that will not have
//received this yet!

Ok(msgs::UpdateFailHTLC {
channel_id: self.channel_id(),
htlc_id,
reason: err_packet
})
}

// Message handlers:

pub fn accept_channel(&mut self, msg: &msgs::AcceptChannel) -> Result<(), HandleError> {
Expand Down Expand Up @@ -1010,7 +1042,7 @@ impl Channel {
}

/// Removes an outbound HTLC which has been commitment_signed by the remote end
fn remove_htlc(&mut self, htlc_id: u64, check_preimage: Option<[u8; 32]>) -> Result<HTLCOutput, HandleError> {
fn remove_outbound_htlc(&mut self, htlc_id: u64, check_preimage: Option<[u8; 32]>) -> Result<HTLCOutput, HandleError> {
let mut found_idx = None;
for (idx, ref htlc) in self.pending_htlcs.iter().enumerate() {
if htlc.outbound && htlc.htlc_id == htlc_id {
Expand All @@ -1026,7 +1058,7 @@ impl Channel {
}
}
match found_idx {
None => Err(HandleError{err: "Remote tried to fulfill an HTLC we couldn't find", msg: None}),
None => Err(HandleError{err: "Remote tried to fulfill/fail an HTLC we couldn't find", msg: None}),
Some(idx) => {
Ok(self.pending_htlcs.swap_remove(idx))
}
Expand Down Expand Up @@ -1096,9 +1128,7 @@ impl Channel {
let mut payment_hash = [0; 32];
sha.result(&mut payment_hash);

//TODO: Tell channel_monitor about the payment_preimage

match self.remove_htlc(msg.htlc_id, Some(payment_hash)) {
match self.remove_outbound_htlc(msg.htlc_id, Some(payment_hash)) {
Err(e) => return Err(e),
Ok(htlc) => {
//TODO: Double-check that we didn't exceed some limits (or value_to_self went
Expand All @@ -1110,43 +1140,40 @@ impl Channel {
self.check_and_free_holding_cell_htlcs()
}


pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC) -> Result<Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>, HandleError> {
pub fn update_fail_htlc(&mut self, msg: &msgs::UpdateFailHTLC) -> Result<([u8; 32], Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>), HandleError> {
if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
return Err(HandleError{err: "Got add HTLC message when channel was not in an operational state", msg: None});
}

//TODO: Lots of checks here (and implementation after the remove?)

match self.remove_htlc(msg.htlc_id, None) {
let payment_hash = match self.remove_outbound_htlc(msg.htlc_id, None) {
Err(e) => return Err(e),
Ok(_htlc) => {
Ok(htlc) => {
//TODO: Double-check that we didn't exceed some limits (or value_to_self went
//negative here?)
////TODO: Something?
htlc.payment_hash
}
}
};

self.check_and_free_holding_cell_htlcs()
let holding_cell_freedom = self.check_and_free_holding_cell_htlcs()?;
Ok((payment_hash, holding_cell_freedom))
}

pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC) -> Result<Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>, HandleError> {
pub fn update_fail_malformed_htlc(&mut self, msg: &msgs::UpdateFailMalformedHTLC) -> Result<([u8; 32], Option<(Vec<msgs::UpdateAddHTLC>, msgs::CommitmentSigned)>), HandleError> {
if (self.channel_state & (ChannelState::ChannelFunded as u32)) != (ChannelState::ChannelFunded as u32) {
return Err(HandleError{err: "Got add HTLC message when channel was not in an operational state", msg: None});
}

//TODO: Lots of checks here (and implementation after the remove?)

match self.remove_htlc(msg.htlc_id, None) {
let payment_hash = match self.remove_outbound_htlc(msg.htlc_id, None) {
Err(e) => return Err(e),
Ok(_htlc) => {
Ok(htlc) => {
//TODO: Double-check that we didn't exceed some limits (or value_to_self went
//negative here?)
////TODO: Something?
htlc.payment_hash
}
}
};

self.check_and_free_holding_cell_htlcs()
let holding_cell_freedom = self.check_and_free_holding_cell_htlcs()?;
Ok((payment_hash, holding_cell_freedom))
}

pub fn commitment_signed(&mut self, msg: &msgs::CommitmentSigned) -> Result<(msgs::RevokeAndACK, Vec<PendingForwardHTLCInfo>), HandleError> {
Expand Down
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