Check RPC server version during client connect.

Fixes #42.

Paymetheus.Rpc/Paymetheus.Rpc.csproj

@@ -46,6 +46,7 @@
     <Compile Include="ProcessExtensions.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="ErrorHandling.cs" />
+    <Compile Include="SemanticVersion.cs" />
     <Compile Include="TimeoutException.cs" />
     <Compile Include="TransactionNotifications.cs" />
     <Compile Include="TransportSecurity.cs" />

Paymetheus.Rpc/SemanticVersion.cs

@@ -0,0 +1,49 @@
+// Copyright (c) 2016 The btcsuite developers
+// Licensed under the ISC license.  See LICENSE file in the project root for full license information.
+
+using System;
+
+namespace Paymetheus.Rpc
+{
+    public struct SemanticVersion
+    {
+        public SemanticVersion(uint major, uint minor, uint patch)
+        {
+            Major = major;
+            Minor = minor;
+            Patch = patch;
+        }
+
+        public uint Major { get; }
+        public uint Minor { get; }
+        public uint Patch { get; }
+
+        public override string ToString() => $"{Major}.{Minor}.{Patch}";
+
+        public static void AssertCompatible(SemanticVersion required, SemanticVersion actual)
+        {
+            if (required.Major != actual.Major)
+                throw IncompatibleVersionException.Major(required, actual);
+            if (required.Minor > actual.Minor)
+                throw IncompatibleVersionException.Minor(required, actual);
+            if (required.Minor == actual.Minor && required.Patch > actual.Patch)
+                throw IncompatibleVersionException.Patch(required, actual);
+        }
+    }
+
+    public class IncompatibleVersionException : Exception
+    {
+        private IncompatibleVersionException(string whatVersion, SemanticVersion required, SemanticVersion actual)
+            : base($"Incompatible {whatVersion} versions: required={required} actual={actual}")
+        { }
+
+        public static IncompatibleVersionException Major(SemanticVersion required, SemanticVersion actual) =>
+            new IncompatibleVersionException("major", required, actual);
+
+        public static IncompatibleVersionException Minor(SemanticVersion required, SemanticVersion actual) =>
+            new IncompatibleVersionException("minor", required, actual);
+
+        public static IncompatibleVersionException Patch(SemanticVersion required, SemanticVersion actual) =>
+            new IncompatibleVersionException("patch", required, actual);
+    }
+}

Paymetheus.Rpc/WalletClient.cs

@@ -20,6 +20,8 @@ namespace Paymetheus.Rpc
 {
     public sealed class WalletClient : IDisposable
     {
+        private static readonly SemanticVersion RequiredRpcServerVersion = new SemanticVersion(0, 3, 0);
+
         public static void Initialize()
         {
             Environment.SetEnvironmentVariable("GRPC_SSL_CIPHER_SUITES", "HIGH+ECDSA");
@@ -67,6 +69,13 @@ public static async Task<WalletClient> ConnectAsync(string networkAddress, strin
                 await channel.ShutdownAsync();
                 throw new ConnectTimeoutException();
             }
+
+            // Ensure the server is running a compatible version.
+            var versionClient = VersionService.NewClient(channel);
+            var response = await versionClient.VersionAsync(new VersionRequest(), deadline: deadline);
+            var serverVersion = new SemanticVersion(response.Major, response.Minor, response.Patch);
+            SemanticVersion.AssertCompatible(RequiredRpcServerVersion, serverVersion);
+
             return new WalletClient(channel);
         }