Add methods to manage channel fee policies and retrieve channels by outpoint

src/Data/Repositories/ChannelRepository.cs

@@ -70,6 +70,13 @@ public ChannelRepository(IRepository<Channel> repository,
             return await applicationDbContext.Channels.Include(x => x.ChannelOperationRequests).FirstOrDefaultAsync(x => x.ChanId.Equals(chanId));
         }
 
+        public async Task<Channel?> GetByOutpoint(OutPoint outpoint)
+        {
+            await using var applicationDbContext = await _dbContextFactory.CreateDbContextAsync();
+
+            return await applicationDbContext.Channels.FirstOrDefaultAsync(c => c.FundingTx == outpoint.Hash.ToString() && c.FundingTxOutputIndex == outpoint.N);
+        }
+
         public async Task<List<Channel>> GetAll()
         {
             await using var applicationDbContext = await _dbContextFactory.CreateDbContextAsync();

src/Data/Repositories/Interfaces/IChannelRepository.cs

@@ -17,6 +17,7 @@
  *
  */
 
+using NBitcoin;
 using Channel = NodeGuard.Data.Models.Channel;
 
 namespace NodeGuard.Data.Repositories.Interfaces;
@@ -68,4 +69,9 @@ public interface IChannelRepository
         string? channelIdFilter = null,
         DateTimeOffset? fromDate = null,
         DateTimeOffset? toDate = null);
+
+    /// <summary>
+    /// Retrieves the channel by the outpoint
+    /// </summary>
+    Task<Channel?> GetByOutpoint(OutPoint outpoint);
 }

src/Proto/nodeguard.proto

@@ -104,6 +104,11 @@ service NodeGuardService {
   Returns a paginated list of rebalances with optional filters.
   */
   rpc GetRebalances(GetRebalancesRequest) returns (GetRebalancesResponse);
+
+  /*
+  Sets the fee policy for a channel
+   */
+  rpc SetChannelFeePolicy(SetChannelFeePolicyRequest) returns (SetChannelFeePolicyResponse);
 }
 
 message GetLiquidityRulesRequest {
@@ -460,6 +465,31 @@ message AddTagsRequest {
 message AddTagsResponse {
 }
 
+message SetChannelFeePolicyRequest {
+  // Channel point in the format <funding_txid>:<output_index>.
+  string chan_point = 1;
+  // Outbound base fee charged for forwarded HTLCs, in millisatoshis.
+  int64 base_fee_msat = 2;
+  // Outbound proportional fee rate in parts-per-million (ppm).
+  uint32 fee_rate_ppm = 3;
+  // Outbound CLTV delta (final timelock delta) in blocks.
+  uint32 time_lock_delta = 4;
+  // Optional inbound fee policy (peer->this node direction).
+  optional InboundFeePolicy inbound_fee_policy = 5;
+  // Managed node pubkey (33-byte hex) where the policy will be applied.
+  string node_pubkey = 6;
+}
+
+message InboundFeePolicy {
+  // Inbound base fee in millisatoshis. Signed to support discounts/rebates.
+  int32 base_fee_msat = 1;
+  // Inbound proportional fee rate in ppm. Signed to support discounts/rebates.
+  int32 fee_rate_ppm = 2;
+}
+
+message SetChannelFeePolicyResponse {
+}
+
 enum REBALANCE_STATUS {
   REBALANCE_PENDING = 0;
   REBALANCE_PROBING = 1;

src/Rpc/NodeGuardService.cs

@@ -60,6 +60,8 @@ Task<GetNewWalletAddressResponse> GetNewWalletAddress(GetNewWalletAddressRequest
     Task<GetRebalanceResponse> GetRebalance(GetRebalanceRequest request, ServerCallContext context);
 
     Task<GetRebalancesResponse> GetRebalances(GetRebalancesRequest request, ServerCallContext context);
+
+    Task<SetChannelFeePolicyResponse> SetChannelFeePolicy(SetChannelFeePolicyRequest request, ServerCallContext context);
 }
 
 /// <summary>
@@ -1368,4 +1370,21 @@ private bool ValidateBitcoinAddress(string address)
 
         return true;
     }
+
+    public override async Task<SetChannelFeePolicyResponse> SetChannelFeePolicy(SetChannelFeePolicyRequest request, ServerCallContext context)
+    {
+        try {
+            await _lightningService.SetChannelFeePolicy(request.ChanPoint, request.NodePubkey, request.BaseFeeMsat, request.FeeRatePpm, request.TimeLockDelta, request.InboundFeePolicy?.BaseFeeMsat, request.InboundFeePolicy?.FeeRatePpm);
+        }
+        catch (ArgumentException e)
+        {
+            throw new RpcException(new Status(StatusCode.InvalidArgument, e.Message));
+        }
+        catch (Exception e)
+        {
+            throw new RpcException(new Status(StatusCode.Internal, e.Message));
+        }
+
+        return new SetChannelFeePolicyResponse();
+    }
 }

src/Services/LightningClientService.cs

@@ -46,6 +46,8 @@ public interface ILightningClientService
     public void FundingStateStepVerify(Node node, PSBT finalizedPSBT, byte[] pendingChannelId, Lightning.LightningClient? client = null);
     public void FundingStateStepFinalize(Node node, PSBT finalizedPSBT, byte[] pendingChannelId, Lightning.LightningClient? client = null);
     public void FundingStateStepCancel(Node node, byte[] pendingChannelId, Lightning.LightningClient? client = null);
+
+    public Task<PolicyUpdateResponse?> SetChannelFeePolicy(Node node, NBitcoin.OutPoint chanPoint, long baseFeeMsat, uint feeRatePpm, uint timeLockDelta, int? inboundBaseFeeMsat, int? inboundFeeRatePpm, Lightning.LightningClient? client = null);
 }
 
 public class LightningClientService : ILightningClientService
@@ -377,4 +379,32 @@ public void FundingStateStepCancel(Node node, byte[] pendingChannelId, Lightning
                 }
             }, new Metadata { { "macaroon", node.ChannelAdminMacaroon } });
     }
+
+    public async Task<PolicyUpdateResponse?> SetChannelFeePolicy(Node node, NBitcoin.OutPoint chanPoint, long baseFeeMsat, uint feeRatePpm, uint timeLockDelta, int? inboundBaseFeeMsat, int? inboundFeeRatePpm, Lightning.LightningClient? client = null)
+    {
+        client ??= GetLightningClient(node.Endpoint);
+
+        var request = new PolicyUpdateRequest
+        {
+            ChanPoint = new ChannelPoint
+            {
+                FundingTxidStr = chanPoint.Hash.ToString(),
+                OutputIndex = chanPoint.N
+            },
+            BaseFeeMsat = baseFeeMsat,
+            FeeRatePpm = feeRatePpm,
+            TimeLockDelta = timeLockDelta
+        };
+
+        if (inboundBaseFeeMsat.HasValue && inboundFeeRatePpm.HasValue)
+        {
+            request.InboundFee = new InboundFee
+            {
+                BaseFeeMsat = inboundBaseFeeMsat.Value,
+                FeeRatePpm = inboundFeeRatePpm.Value
+            };
+        }
+
+        return await client.UpdateChannelPolicyAsync(request, new Metadata { { "macaroon", node.ChannelAdminMacaroon } });
+    }
 }

src/Services/LightningService.cs

@@ -34,6 +34,7 @@
 using Routerrpc;
 using Channel = NodeGuard.Data.Models.Channel;
 using Transaction = NBitcoin.Transaction;
+using OutPoint = NBitcoin.OutPoint;
 
 // ReSharper disable InconsistentNaming
 
@@ -184,7 +185,20 @@ Task<Payment> SendPaymentV2Async(Node node, string paymentRequest, long feeLimit
         /// a specific channel. If the peer has multiple channels with us, the first one
         /// returned by ListChannels is used as a representative.
         /// </summary>
-        Task<long?> GetLocalOutboundFeeRatePpmByPeerAsync(Node node, string peerPubkey);
+        Task<long?> GetLocalOutboundFeeRatePpmByPeerAsync
+        (Node node, string peerPubkey);
+        /// <summary>
+        /// Sets the channel fee policy for a given channel identified by its chanPoint
+        /// </summary>
+        /// <param name="chanPoint"></param>
+        /// <param name="nodePubKey"></param>
+        /// <param name="baseFeeMsat"></param>
+        /// <param name="feeRatePpm"></param>
+        /// <param name="timeLockDelta"></param>
+        /// <param name="inboundBaseFeeMsat"></param>
+        /// <param name="inboundFeeRatePpm"></param>
+        /// <returns></returns>
+        public Task SetChannelFeePolicy(string chanPoint, string nodePubKey, long baseFeeMsat, uint feeRatePpm, uint timeLockDelta, int? inboundBaseFeeMsat, int? inboundFeeRatePpm);
     }
 
     /// <summary>
@@ -1801,5 +1815,106 @@ public async Task<Payment> SendPaymentV2Async(Node node, string paymentRequest,
 
             return await GetLocalOutboundFeeRatePpmAsync(node, match.ChanId);
         }
+
+        public async Task SetChannelFeePolicy(string chanPoint, string nodePubKey, long baseFeeMsat, uint feeRatePpm, uint timeLockDelta, int? inboundBaseFeeMsat, int? inboundFeeRatePpm)
+        {
+            // Validate chanPoint format
+            if (!OutPoint.TryParse(chanPoint, out var outPoint))
+            {
+                throw new ArgumentException("Invalid chanPoint format.", nameof(chanPoint));
+            }
+
+            if (string.IsNullOrWhiteSpace(nodePubKey))
+            {
+                throw new ArgumentException("Node pubkey is required.", nameof(nodePubKey));
+            }
+
+            // Validate inbound fee policy parameters
+            if (inboundBaseFeeMsat.HasValue != inboundFeeRatePpm.HasValue)
+            {
+                throw new ArgumentException("Both inboundBaseFeeMsat and inboundFeeRatePpm must be provided together for inbound fee policy.");
+            }
+
+            if (inboundBaseFeeMsat.HasValue && inboundBaseFeeMsat.Value > 0)
+            {
+                throw new ArgumentException("Inbound base fee must be lower or equal to zero.", nameof(inboundBaseFeeMsat));
+            }
+
+            if (inboundFeeRatePpm.HasValue && inboundFeeRatePpm.Value > 0)
+            {
+                throw new ArgumentException("Inbound fee rate must be lower or equal to zero.", nameof(inboundFeeRatePpm));
+            }
+
+            var channel = await _channelRepository.GetByOutpoint(outPoint);
+            if (channel == null)
+            {
+                throw new ArgumentException("Channel not found for the given chanPoint.", nameof(chanPoint));
+            }
+
+            var node = await _nodeRepository.GetByPubkey(nodePubKey);
+            if (node == null)
+            {
+                throw new ArgumentException("Node not found for the given nodePubKey.", nameof(nodePubKey));
+            }
+
+            if (channel.SourceNodeId != node.Id && channel.DestinationNodeId != node.Id)
+            {
+                throw new ArgumentException("The given nodePubKey is not a participant of the channel.", nameof(nodePubKey));
+            }
+
+            if (!node.IsManaged || string.IsNullOrWhiteSpace(node.ChannelAdminMacaroon))
+            {
+                throw new ArgumentException("The given nodePubKey is not a managed node with channel admin access.", nameof(nodePubKey));
+            }
+
+            try
+            {
+                var response = await _lightningClientService.SetChannelFeePolicy(node, outPoint, baseFeeMsat, feeRatePpm, timeLockDelta, inboundBaseFeeMsat, inboundFeeRatePpm);
+
+                if (response?.FailedUpdates != null && response.FailedUpdates.Count > 0)
+                {
+                    _logger.LogError("Failed to update fee policy for channel: {ChanPoint}", chanPoint);
+                    throw new Exception($"Failed to update fee policy for channel: {chanPoint}");
+                }
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "Error while setting channel fee policy for chanPoint: {ChanPoint}", chanPoint);
+                throw new Exception($"Error while setting channel fee policy for chanPoint: {chanPoint}");
+            }
+
+            try
+            {
+                await using var applicationDbContext = await _dbContextFactory.CreateDbContextAsync();
+
+                await applicationDbContext.AuditLogs.AddAsync(new AuditLog
+                {
+                    ActionType = AuditActionType.Update,
+                    EventType = AuditEventType.Success,
+                    ObjectAffected = AuditObjectType.Channel,
+                    ObjectId = channel.Id.ToString(),
+                    Username = "SYSTEM",
+                    Details = System.Text.Json.JsonSerializer.Serialize(new
+                    {
+                        ChanPoint = chanPoint,
+                        ChannelId = channel.Id,
+                        channel.ChanId,
+                        NodeId = node.Id,
+                        NodePubKey = node.PubKey,
+                        BaseFeeMsat = baseFeeMsat,
+                        FeeRatePpm = feeRatePpm,
+                        TimeLockDelta = timeLockDelta,
+                        InboundBaseFeeMsat = inboundBaseFeeMsat,
+                        InboundFeeRatePpm = inboundFeeRatePpm
+                    })
+                });
+
+                await applicationDbContext.SaveChangesAsync();
+            }
+            catch (Exception e)
+            {
+                _logger.LogError(e, "Error while saving channel fee policy audit log for chanPoint: {ChanPoint}", chanPoint);
+            }
+        }
     }
-}
+}

test/NodeGuard.Tests/Data/Repositories/ChannelRepositoryTests.cs

@@ -27,6 +27,7 @@
 using Lnrpc;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
+using NBitcoin;
 using Quartz;
 using Channel = NodeGuard.Data.Models.Channel;
 
@@ -186,4 +187,56 @@ public async Task MarkAsClosed_Negative_ChannelFound()
         channel.Status.Should().Be(Channel.ChannelStatus.Open);
         result.Item2.Should().NotBeNull();
     }
-}
+
+    [Fact]
+    public async Task GetByOutpoint_ReturnsMatchingChannel()
+    {
+        // Arrange
+        var options = new DbContextOptionsBuilder<ApplicationDbContext>()
+            .UseInMemoryDatabase(databaseName: $"ChannelRepositoryTests_{Guid.NewGuid()}")
+            .Options;
+        var dbContextFactory = new Mock<IDbContextFactory<ApplicationDbContext>>();
+        dbContextFactory
+            .Setup(x => x.CreateDbContextAsync(default))
+            .ReturnsAsync(() => new ApplicationDbContext(options));
+
+        var fundingTx = "0000000000000000000000000000000000000000000000000000000000000001";
+        await using (var context = new ApplicationDbContext(options))
+        {
+            context.Channels.AddRange(
+                new Channel
+                {
+                    Id = 1,
+                    FundingTx = fundingTx,
+                    FundingTxOutputIndex = 2,
+                    ChanId = 100,
+                    Status = Channel.ChannelStatus.Open
+                },
+                new Channel
+                {
+                    Id = 2,
+                    FundingTx = fundingTx,
+                    FundingTxOutputIndex = 3,
+                    ChanId = 101,
+                    Status = Channel.ChannelStatus.Open
+                });
+            await context.SaveChangesAsync();
+        }
+
+        var channelRepository = new ChannelRepository(
+            new Mock<IRepository<Channel>>().Object,
+            new Mock<ILogger<ChannelRepository>>().Object,
+            dbContextFactory.Object,
+            new Mock<IChannelOperationRequestRepository>().Object,
+            new Mock<ISchedulerFactory>().Object,
+            new Mock<IMapper>().Object,
+            new Mock<ILightningClientService>().Object);
+
+        // Act
+        var result = await channelRepository.GetByOutpoint(NBitcoin.OutPoint.Parse($"{fundingTx}:2"));
+
+        // Assert
+        result.Should().NotBeNull();
+        result!.Id.Should().Be(1);
+    }
+}