Actually apply update fee messages

Prior to this commit, apply an update_fee message would cause DNL to
validate the message but not actually apply it to its commitments.

It now updates its commitments as it should.

Upstream PR: joemphilips#159

Author: canndrew

src/DotNetLightning.Core/Channel/Channel.fs

@@ -882,7 +882,8 @@ module Channel =
 
         | WeAcceptedOperationUpdateFee(_msg, newCommitments), ChannelState.Normal d ->
             { c with State = ChannelState.Normal({ d with Commitments = newCommitments }) }
-        | WeAcceptedUpdateFee(_msg), ChannelState.Normal _d -> c
+        | WeAcceptedUpdateFee(_msg, newCommitments), ChannelState.Normal normalData ->
+            { c with State = ChannelState.Normal({ normalData with Commitments = newCommitments }) }
 
         | WeAcceptedOperationSign(_msg, newCommitments), ChannelState.Normal d ->
             { c with State = ChannelState.Normal({ d with Commitments = newCommitments }) }

src/DotNetLightning.Core/Channel/ChannelTypes.fs

@@ -285,7 +285,7 @@ type ChannelEvent =
     | WeAcceptedFailMalformedHTLC of origin: HTLCSource * msg: UpdateAddHTLCMsg * newCommitments: Commitments
 
     | WeAcceptedOperationUpdateFee of msg: UpdateFeeMsg  * nextCommitments: Commitments
-    | WeAcceptedUpdateFee of msg: UpdateFeeMsg 
+    | WeAcceptedUpdateFee of msg: UpdateFeeMsg * newCommitments: Commitments
 
     | WeAcceptedOperationSign of msg: CommitmentSignedMsg * nextCommitments: Commitments
     | WeAcceptedCommitmentSigned of msg: RevokeAndACKMsg * nextCommitments: Commitments

src/DotNetLightning.Core/Channel/CommitmentsModule.fs

@@ -251,19 +251,22 @@ module internal Commitments =
         else
             result {
                 do! Helpers.checkUpdateFee (config) (msg) (localFeerate)
-                let c1 = cm.AddRemoteProposal(msg)
+                let nextCommitments = cm.AddRemoteProposal(msg)
                 let! reduced =
-                    c1.LocalCommit.Spec.Reduce(c1.LocalChanges.ACKed, c1.RemoteChanges.Proposed) |> expectTransactionError
+                    nextCommitments.LocalCommit.Spec.Reduce(
+                        nextCommitments.LocalChanges.ACKed,
+                        nextCommitments.RemoteChanges.Proposed
+                    ) |> expectTransactionError
 
-                let fees = Transactions.commitTxFee(c1.RemoteParams.DustLimitSatoshis) reduced
-                let missing = reduced.ToRemote.ToMoney() - c1.RemoteParams.ChannelReserveSatoshis - fees
+                let fees = Transactions.commitTxFee(nextCommitments.RemoteParams.DustLimitSatoshis) reduced
+                let missing = reduced.ToRemote.ToMoney() - nextCommitments.RemoteParams.ChannelReserveSatoshis - fees
                 if (missing < Money.Zero) then
                     return!
-                        (c1.LocalParams.ChannelReserveSatoshis, fees,  (-1 * missing))
+                        (nextCommitments.LocalParams.ChannelReserveSatoshis, fees,  (-1 * missing))
                         |> cannotAffordFee
                 else
                     return
-                        [ WeAcceptedUpdateFee msg ]
+                        [ WeAcceptedUpdateFee(msg, nextCommitments) ]
             }
 
     let sendCommit (channelPrivKeys: ChannelPrivKeys) (n: Network) (cm: Commitments) =