LND: Simple channel closing implementation

src/BTCPayServer.Lightning.Common/CloseChannelRequest.cs

@@ -0,0 +1,27 @@
+using System;
+
+namespace BTCPayServer.Lightning
+{
+    public class CloseChannelRequest
+    {
+        public NodeInfo NodeInfo
+        {
+            get; set;
+        }
+        public string ChannelPointFundingTxIdStr
+        {
+            get; set;
+        }
+        public long ChannelPointOutputIndex
+        {
+            get; set;
+        }
+        public static void AssertIsSane(CloseChannelRequest closeChannelRequest)
+        {
+            if (closeChannelRequest == null)
+                throw new ArgumentNullException(nameof(closeChannelRequest));
+            if (closeChannelRequest.ChannelPointFundingTxIdStr == null)
+                throw new ArgumentNullException(nameof(closeChannelRequest.ChannelPointFundingTxIdStr));
+        }
+    }
+}

src/BTCPayServer.Lightning.Common/CloseChannelResponse.cs

@@ -0,0 +1,20 @@
+namespace BTCPayServer.Lightning
+{
+    public enum CloseChannelResult
+    {
+        Ok,
+        Failed,
+    }
+
+    public class CloseChannelResponse
+    {
+        public CloseChannelResponse(CloseChannelResult result)
+        {
+            Result = result;
+        }
+        public CloseChannelResult Result
+        {
+            get; set;
+        }
+    }
+}

src/BTCPayServer.Lightning.Common/OpenChannelResponse.cs

@@ -23,5 +23,9 @@ public OpenChannelResult Result
         {
             get; set;
         }
+        public string FundingTxIdIfAvailable
+        {
+            get; set;
+        }
     }
 }

src/BTCPayServer.Lightning.LND/LndClient.cs

@@ -373,7 +373,9 @@ async Task<OpenChannelResponse> ILightningClient.OpenChannel(OpenChannelRequest
                     req.Sat_per_byte = ((int)openChannelRequest.FeeRate.SatoshiPerByte).ToString();
                 }
                 var result = await this.SwaggerClient.OpenChannelSyncAsync(req, cancellation);
-                return new OpenChannelResponse(OpenChannelResult.Ok);
+                var res = new OpenChannelResponse(OpenChannelResult.Ok);
+                res.FundingTxIdIfAvailable = result.Funding_txid_str;
+                return res;
             }
             catch(SwaggerException ex) when
                 (ex.AsLNDError() is LndError2 lndError &&
@@ -427,6 +429,22 @@ async Task<OpenChannelResponse> ILightningClient.OpenChannel(OpenChannelRequest
             }
         }
 
+        public async Task<CloseChannelResponse> CloseChannel(CloseChannelRequest closeChannelRequest, CancellationToken cancellation)
+        {
+            CloseChannelRequest.AssertIsSane(closeChannelRequest);
+            cancellation.ThrowIfCancellationRequested();
+            try
+            {
+                var result = await this.SwaggerClient.CloseChannelAsync(closeChannelRequest.ChannelPointFundingTxIdStr, closeChannelRequest.ChannelPointOutputIndex, cancellation);
+                return new CloseChannelResponse(CloseChannelResult.Ok);
+            }
+            catch (Exception)
+            {
+                throw;
+                //return new CloseChannelResponse(CloseChannelResult.Failed);
+            }
+        }
+
         async Task<BitcoinAddress> ILightningClient.GetDepositAddress()
         {
             return BitcoinAddress.Create((await SwaggerClient.NewWitnessAddressAsync()).Address, Network);

src/BTCPayServer.Lightning.All/ConnectChannels.cs → tests/ChannelSetup.cs

@@ -14,9 +14,9 @@ namespace BTCPayServer.Lightning.Tests
     /// <summary>
     /// Utilities to connect channels on regtest 
     /// </summary>
-    public static class ConnectChannels
+    public static class ChannelSetup
     {
-        static ConnectChannels()
+        static ChannelSetup()
         {
             Logs = NullLogger.Instance;
         }
@@ -26,13 +26,13 @@ public static ILogger Logs
             set;
         }
         /// <summary>
-        /// Create channels from all senders to all receivers while mining on cashCow
+        /// Open channels from all senders to all receivers while mining on cashCow
         /// </summary>
         /// <param name="cashCow">The miner and liquidity source</param>
         /// <param name="senders">Senders of payment on Lightning Network</param>
         /// <param name="receivers">Receivers of payment on Lightning Network</param>
         /// <returns></returns>
-        public static async Task ConnectAll(RPCClient cashCow, IEnumerable<ILightningClient> senders, IEnumerable<ILightningClient> receivers)
+        public static async Task OpenAll(RPCClient cashCow, IEnumerable<ILightningClient> senders, IEnumerable<ILightningClient> receivers)
         {
             if(await cashCow.GetBlockCountAsync() <= cashCow.Network.Consensus.CoinbaseMaturity)
             {
@@ -44,11 +44,20 @@ public static async Task ConnectAll(RPCClient cashCow, IEnumerable<ILightningCli
             {
                 foreach(var dest in receivers)
                 {
-                    await CreateChannel(cashCow, sender, dest);
+                    await OpenChannel(cashCow, sender, dest);
                 }
             }
         }
-        public static async Task CreateChannel(RPCClient cashCow, ILightningClient sender, ILightningClient dest)
+
+        private static Dictionary<(ILightningClient, ILightningClient), string> availableFundingTxIds
+            = new Dictionary<(ILightningClient, ILightningClient), string>();
+
+        internal static string GetFundingTxIdForChannel(ILightningClient sender, ILightningClient dest)
+        {
+            return availableFundingTxIds.GetValueOrDefault((sender, dest));
+        }
+
+        public static async Task OpenChannel(RPCClient cashCow, ILightningClient sender, ILightningClient dest)
         {
             var destInfo = await dest.GetInfo();
             var destInvoice = await dest.CreateInvoice(1000, "EnsureConnectedToDestination", TimeSpan.FromSeconds(5000));
@@ -115,6 +124,8 @@ public static async Task CreateChannel(RPCClient cashCow, ILightningClient sende
                     }
                     if(openChannel.Result == OpenChannelResult.Ok)
                     {
+                        if (!String.IsNullOrEmpty(openChannel.FundingTxIdIfAvailable))
+                            availableFundingTxIds[(sender, dest)] = openChannel.FundingTxIdIfAvailable;
                         // generate one block and a bit more time to confirm channel opening
                         await cashCow.GenerateAsync(1);
                         await WaitLNSynched(cashCow, sender);

tests/CommonTests.cs

@@ -15,6 +15,76 @@ namespace BTCPayServer.Lightning.Tests
 {
 	public class CommonTests
 	{
+		uint CountJsonObjects(string jsonString)
+		{
+			uint countJsonInner(char? head, string tail, uint braceNestingLevel, bool insideSubString, uint acc)
+			{
+				if (!head.HasValue)
+				{
+					if (braceNestingLevel != 0)
+						throw new ArgumentException("jsonString seems to be invalid");
+					return acc;
+				}
+
+				char? newHead = null;
+				if (!String.IsNullOrEmpty(tail))
+					newHead = tail.First();
+				var newTail = newHead == null ? null : tail.Substring(1);
+
+				if (!insideSubString && head == '"') {
+					return countJsonInner(newHead, newTail, braceNestingLevel, true, acc);
+				}
+				if (insideSubString)
+				{
+					if (head == '"')
+						return countJsonInner(newHead, newTail, braceNestingLevel, false, acc);
+					return countJsonInner(newHead, newTail, braceNestingLevel, insideSubString, acc);
+				}
+
+				if (head == '{')
+					return countJsonInner(newHead, newTail, braceNestingLevel + 1, insideSubString, acc);
+				else if (head == '}')
+				{
+					if (braceNestingLevel == 0)
+						throw new ArgumentException("jsonString seems to be invalid");
+					var newNestingLevel = braceNestingLevel - 1;
+					var newAcc = (newNestingLevel == 0) ? acc + 1 : acc;
+					return countJsonInner(newHead, newTail, newNestingLevel, insideSubString, newAcc);
+				}
+				else
+					return countJsonInner(newHead, newTail, braceNestingLevel, insideSubString, acc);
+			}
+
+			if (jsonString == string.Empty)
+				return 0;
+			if (!jsonString.StartsWith("{"))
+				throw new ArgumentException("jsonString should start with {");
+			if (!jsonString.EndsWith("}"))
+				throw new ArgumentException("jsonString should end with }");
+
+			return countJsonInner(jsonString.First(), jsonString.Substring(1), 0, false, 0);
+		}
+
+		[Fact()]
+		public void JsonCounter()
+		{
+			Assert.Equal(0u, CountJsonObjects(String.Empty));
+
+			Assert.Throws<ArgumentException>(() => CountJsonObjects("x")); // not startswith {
+			Assert.Throws<ArgumentException>(() => CountJsonObjects("{x")); // not endswith }
+
+			Assert.Equal(1u, CountJsonObjects("{ \"foo\": 1 }"));
+			Assert.Equal(2u, CountJsonObjects("{ \"foo\": 1 }{ \"bar\": 2 }"));
+			Assert.Equal(3u, CountJsonObjects("{ \"foo\": 1 }{ \"bar\": 2 }{ \"baz\": 3 }"));
+
+			// ends with bad nesting level
+			Assert.Throws<ArgumentException>(() => CountJsonObjects("{{x}"));
+			Assert.Throws<ArgumentException>(() => CountJsonObjects("{x}}"));
+
+			// edge case
+			Assert.Equal(1u, CountJsonObjects("{ \"foo\": \"{\" }"));
+		}
+
 #if DEBUG
 		public const int Timeout = 20 * 60 * 1000;
 #else
@@ -25,7 +95,7 @@ public CommonTests(ITestOutputHelper helper)
 			Docker = !string.IsNullOrEmpty(Environment.GetEnvironmentVariable("IN_DOCKER_CONTAINER"));
 			Logs.Tester = new XUnitLog(helper) { Name = "Tests" };
 			Logs.LogProvider = new XUnitLogProvider(helper);
-			ConnectChannels.Logs = Logs.LogProvider.CreateLogger("Tests");
+			ChannelSetup.Logs = Logs.LogProvider.CreateLogger("Tests");
 		}
 
 		public static bool Docker { get; set; }
@@ -271,7 +341,7 @@ private async Task EnsureConnectedToDestinations((string Name, ILightningClient
 		{
 			await Task.WhenAll(WaitServersAreUp($"{test.Name} (Customer)", test.Customer), WaitServersAreUp($"{test.Name} (Merchant)", test.Merchant));
 			Tests.Logs.Tester.LogInformation($"{test.Name}: Connecting channels...");
-			await ConnectChannels.ConnectAll(Tester.CreateRPC(), new[] { test.Customer }, new[] { test.Merchant });
+			await ChannelSetup.OpenAll(Tester.CreateRPC(), new[] { test.Customer }, new[] { test.Merchant });
 			Tests.Logs.Tester.LogInformation($"{test.Name}: Channels connected");
 		}
 
@@ -536,5 +606,30 @@ public void CanParseLightningURL()
 			Assert.True(LightningConnectionString.TryParse("type=charge;server=http://api-token:foiewnccewuify@127.0.0.1:54938/;allowinsecure=true", out conn));
 			Assert.Equal("type=charge;server=http://127.0.0.1:54938/;api-token=foiewnccewuify;allowinsecure=true", conn.ToString());
 		}
+
+		[Fact(Timeout = Timeout)]
+		public async Task CanCloseLndChannel()
+		{
+			// TODO: test in all LN implementations, not just LND
+			//foreach (var test in Tester.GetTestedPairs())
+			//{
+				var test = Tester.GetTestedLndPair();
+				await EnsureConnectedToDestinations(test);
+				var customer = (ILightningClient)test.Customer;
+				var senderChannel = (await customer.ListChannels()).First();
+
+				var senderInfo = await customer.GetInfo();
+				var fundingTxIdForChannel = ChannelSetup.GetFundingTxIdForChannel(customer, test.Merchant);
+				if (String.IsNullOrEmpty(fundingTxIdForChannel))
+					throw new InvalidOperationException("Could not find funding Tx ID of channel");
+				var closeChannelRequest = new CloseChannelRequest()
+				{
+					NodeInfo = senderInfo.NodeInfoList.First(),
+					ChannelPointOutputIndex = senderChannel.ChannelPoint.N,
+					ChannelPointFundingTxIdStr = fundingTxIdForChannel
+				};
+				await test.Merchant.CloseChannel(closeChannelRequest, CancellationToken.None);
+			//}
+		}
 	}
 }

tests/Tester.cs

@@ -87,11 +87,18 @@ public static LndClient CreateLndClientDest()
 			yield return ("Eclair (Client)", CreateEclairClient());
 		}
 
+		private static (string Name, ILightningClient Customer, ILightningClient Merchant) GetTestedCLightningPair()
+			=> ("C-Lightning", CreateCLightningClient(), CreateCLightningClientDest());
+		internal static (string Name, LndClient Customer, LndClient Merchant) GetTestedLndPair()
+			=> ("LND", CreateLndClient(), CreateLndClientDest());
+		private static (string Name, ILightningClient Customer, ILightningClient Merchant) GetTestedEclairPair()
+			=> ("Eclair", CreateEclairClient(), CreateEclairClientDest());
+
 		public static IEnumerable<(string Name, ILightningClient Customer, ILightningClient Merchant)> GetTestedPairs()
 		{
-			yield return ("C-Lightning", CreateCLightningClient(), CreateCLightningClientDest());
-			yield return ("LND", CreateLndClient(), CreateLndClientDest());
-			yield return ("Eclair", CreateEclairClient(), CreateEclairClientDest());
+			yield return GetTestedCLightningPair();
+			yield return GetTestedLndPair();
+			yield return GetTestedEclairPair();
 		}
 	}
 }