Add support for option_support_large_channel

This commit adds support for option_support_large_channel
and there are some changes made to validation process;
more specifically when validating our OpenChannel msg,
instead of just sending out an Error if the funding_satoshis
is greater than the limit, we check if support_large_channel
is activated as mandatory (cause if we don't set that option as
mandatory the openChannel will be invalid if sent to a peet with
no support for support_large_channel) and also when we are validating
someone else's openChannelMsg, we check that we have
support_large_channel option activated (it doesn't matter if mandatory
or optional).

src/DotNetLightning.Core/Channel/Channel.fs

@@ -176,7 +176,7 @@ module Channel =
                 ShutdownScriptPubKey = cs.Config.ChannelOptions.ShutdownScriptPubKey
             }
             result {
-                do! Validation.checkOurOpenChannelMsgAcceptable (cs.Config) openChannelMsgToSend
+                do! Validation.checkOurOpenChannelMsgAcceptable (cs.Config) openChannelMsgToSend inputInitFunder.LocalParams
                 return [
                     NewOutboundChannelStarted(
                         openChannelMsgToSend, {
@@ -290,8 +290,8 @@ module Channel =
             makeChannelReestablish cs.ChannelPrivKeys state
         | WaitForOpenChannel state, ApplyOpenChannel msg ->
             result {
-                do! Validation.checkOpenChannelMsgAcceptable (cs.FeeEstimator) (cs.Config) msg
                 let localParams = state.InitFundee.LocalParams
+                do! Validation.checkOpenChannelMsgAcceptable (cs.FeeEstimator) (cs.Config) msg localParams
                 let channelKeys = state.InitFundee.ChannelPrivKeys
                 let localCommitmentPubKey = channelKeys.CommitmentSeed.DerivePerCommitmentPoint CommitmentNumber.FirstCommitment
                 let acceptChannelMsg: AcceptChannelMsg = {

src/DotNetLightning.Core/Channel/ChannelError.fs

@@ -5,6 +5,7 @@ open NBitcoinExtensions
 open DotNetLightning.Utils.OnionError
 open DotNetLightning.Chain
 open DotNetLightning.Crypto
+open DotNetLightning.Serialization
 open DotNetLightning.Serialization.Msgs
 open DotNetLightning.Transactions
 
@@ -323,9 +324,21 @@ module internal OpenChannelMsgValidation =
         else
             Ok()
 
-    let checkFundingSatoshisLessThanMax (msg: OpenChannelMsg) =
-        if (msg.FundingSatoshis >= ChannelConstants.MAX_FUNDING_SATOSHIS) then
-            sprintf "funding_satoshis must be less than %A. It was %A" ChannelConstants.MAX_FUNDING_SATOSHIS msg.FundingSatoshis
+    let checkFundingSatoshisLessThanMax (msg: OpenChannelMsg) (localParams: LocalParams) (isOurOpenChannelMsg: bool) =
+        // If we are validating our own open message we make sure we are forcing support for option_support_large_channel on the other peer
+        let featureType =
+            match isOurOpenChannelMsg with
+            | true ->
+                Some FeaturesSupport.Mandatory
+            | false ->
+                None
+
+        if msg.FundingSatoshis >= ChannelConstants.MAX_FUNDING_SATOSHIS && 
+                not (localParams.Features.HasFeature (Feature.OptionSupportLargeChannel, ?featureType = featureType)) then
+            sprintf 
+                "funding_satoshis must be less than %A. It was %A, consider activating option_support_large_channel feature." 
+                ChannelConstants.MAX_FUNDING_SATOSHIS 
+                msg.FundingSatoshis
             |> Error
         else
             Ok()

src/DotNetLightning.Core/Channel/ChannelValidation.fs

@@ -161,18 +161,18 @@ module internal ChannelHelpers =
 module internal Validation =
 
     open DotNetLightning.Channel
-    let checkOurOpenChannelMsgAcceptable (_conf: ChannelConfig) (msg: OpenChannelMsg) =
-        Validation.ofResult(OpenChannelMsgValidation.checkFundingSatoshisLessThanMax msg)
+    let checkOurOpenChannelMsgAcceptable (_conf: ChannelConfig) (msg: OpenChannelMsg) (localParams: LocalParams) =
+        Validation.ofResult(OpenChannelMsgValidation.checkFundingSatoshisLessThanMax msg localParams true)
         *^> OpenChannelMsgValidation.checkChannelReserveSatohisLessThanFundingSatoshis msg
         *^> OpenChannelMsgValidation.checkPushMSatLesserThanFundingValue msg
         *^> OpenChannelMsgValidation.checkFundingSatoshisLessThanDustLimitSatoshis msg
         *^> OpenChannelMsgValidation.checkMaxAcceptedHTLCs msg
         *^> OpenChannelMsgValidation.checkFunderCanAffordFee (msg.FeeRatePerKw) msg
         |> Result.mapError((@)["open_channel msg is invalid"] >> InvalidOpenChannelError.Create msg >> InvalidOpenChannel)
 
-    let internal checkOpenChannelMsgAcceptable (feeEstimator: IFeeEstimator) (conf: ChannelConfig) (msg: OpenChannelMsg) =
+    let internal checkOpenChannelMsgAcceptable (feeEstimator: IFeeEstimator) (conf: ChannelConfig) (msg: OpenChannelMsg) (localParams: LocalParams) =
         let feeRate = feeEstimator.GetEstSatPer1000Weight(ConfirmationTarget.Background)
-        Validation.ofResult(OpenChannelMsgValidation.checkFundingSatoshisLessThanMax msg)
+        Validation.ofResult(OpenChannelMsgValidation.checkFundingSatoshisLessThanMax msg localParams false)
         *^> OpenChannelMsgValidation.checkChannelReserveSatohisLessThanFundingSatoshis msg
         *^> OpenChannelMsgValidation.checkPushMSatLesserThanFundingValue msg
         *^> OpenChannelMsgValidation.checkFundingSatoshisLessThanDustLimitSatoshis msg

src/DotNetLightning.Core/Serialization/Features.fs

@@ -142,6 +142,7 @@ module internal Feature =
               yield Feature.PaymentSecret
               // TODO: support this feature
               // Feature.BasicMultiPartPayment
+              yield Feature.OptionSupportLargeChannel
           }
         |> Seq.map(fun f -> f.Mandatory)
         |> Set

tests/DotNetLightning.Core.Tests/Serialization.fs

@@ -834,7 +834,7 @@ module SerializationTest =
                         1L <<< Feature.BasicMultiPartPayment.MandatoryBitPosition, false
                         1L <<< Feature.BasicMultiPartPayment.OptionalBitPosition, true
 
-                        1L <<< Feature.OptionSupportLargeChannel.MandatoryBitPosition, false
+                        1L <<< Feature.OptionSupportLargeChannel.MandatoryBitPosition, true
                         1L <<< Feature.OptionSupportLargeChannel.OptionalBitPosition, true
                     ]
                 for (s, expected) in testCases do
@@ -860,8 +860,9 @@ module SerializationTest =
                     // unknown optional feature bits
                     |> Map.add "            10000000000000000000" true
                     |> Map.add "        001000000000000000000000" true
+                    // support_large_channel_option(mandatory)
+                    |> Map.add "        000001000000000000000000" true
                     // those are useful for nonreg testing of the areSupported method (which needs to be updated with every new supported mandatory bit)
-                    |> Map.add "        000001000000000000000000" false
                     |> Map.add "        000100000000000000000000" false
                     |> Map.add "        010000000000000000000000" false
                     |> Map.add "    0001000000000000000000000000" false