Correctly update cached addresses for accepted Channels. (#98)

Motivation:

We missed to correctly update the cached remote and local addresses for accepted Channels. Because of this localAddress and remoteAddr always returned nil.

Modifications:

- Update cached addresses when constructing SocketChannel from existing Socket.
- Add testcase

Result:

Fixes [#97].

Sources/NIO/SocketChannel.swift

@@ -206,6 +206,9 @@ class BaseSocketChannel<T: BaseSocket>: SelectableChannel, ChannelCore {
         self.active.store(false)
         self.recvAllocator = recvAllocator
         self._pipeline = ChannelPipeline(channel: self)
+        // As the socket may already be connected we should ensure we start with the correct addresses cached.
+        self.localAddressCached.store(Box(try? socket.localAddress()))
+        self.remoteAddressCached.store(Box(try? socket.remoteAddress()))
     }
 
     deinit {

Tests/NIOTests/ChannelTests+XCTest.swift

@@ -55,6 +55,7 @@ extension ChannelTests {
                 ("testRejectsInvalidData", testRejectsInvalidData),
                 ("testWeDontCrashIfChannelReleasesBeforePipeline", testWeDontCrashIfChannelReleasesBeforePipeline),
                 ("testAskForLocalAndRemoteAddressesAfterChannelIsClosed", testAskForLocalAndRemoteAddressesAfterChannelIsClosed),
+                ("testReceiveAddressAfterAccept", testReceiveAddressAfterAccept),
            ]
    }
 }

Tests/NIOTests/ChannelTests.swift

@@ -1412,4 +1412,34 @@ public class ChannelTests: XCTestCase {
             XCTAssertNil(f)
         }
     }
+
+    func testReceiveAddressAfterAccept() throws {
+        let group = MultiThreadedEventLoopGroup(numThreads: 1)
+        defer {
+            XCTAssertNoThrow(try group.syncShutdownGracefully())
+        }
+
+        class AddressVerificationHandler : ChannelInboundHandler {
+            typealias InboundIn = Never
+
+            public func channelActive(ctx: ChannelHandlerContext) {
+                XCTAssertNotNil(ctx.channel.localAddress)
+                XCTAssertNotNil(ctx.channel.remoteAddress)
+                ctx.channel.close(promise: nil)
+            }
+        }
+
+        let serverChannel = try ServerBootstrap(group: group)
+            .serverChannelOption(ChannelOptions.socket(SocketOptionLevel(SOL_SOCKET), SO_REUSEADDR), value: 1)
+            .childChannelInitializer { ch in
+                ch.pipeline.add(handler: AddressVerificationHandler())
+            }
+            .bind(host: "127.0.0.1", port: 0).wait()
+
+        let clientChannel = try ClientBootstrap(group: group)
+            .connect(to: serverChannel.localAddress!).wait()
+
+        try clientChannel.closeFuture.wait()
+        try serverChannel.syncCloseAcceptingAlreadyClosed()
+    }
 }