Tolerate out-of-band ports. (#112)

Motivation:

We shouldn't crash if the user gives us a bad port.

Modifications:

- Check the ports are in-band before we move on.

Result:

We won't crash.

Sources/NIOTransportServices/NIOTSConnectionBootstrap.swift

@@ -156,6 +156,11 @@ public final class NIOTSConnectionBootstrap {
     ///     - port: The port to connect to.
     /// - returns: An `EventLoopFuture<Channel>` to deliver the `Channel` when connected.
     public func connect(host: String, port: Int) -> EventLoopFuture<Channel> {
+        let validPortRange = Int(UInt16.min)...Int(UInt16.max)
+        guard validPortRange.contains(port) else {
+            return self.group.next().makeFailedFuture(NIOTSErrors.InvalidPort(port: port))
+        }
+
         guard let actualPort = NWEndpoint.Port(rawValue: UInt16(port)) else {
             return self.group.next().makeFailedFuture(NIOTSErrors.InvalidPort(port: port))
         }

Sources/NIOTransportServices/NIOTSListenerBootstrap.swift

@@ -249,6 +249,11 @@ public final class NIOTSListenerBootstrap {
     ///     - host: The host to bind on.
     ///     - port: The port to bind on.
     public func bind(host: String, port: Int) -> EventLoopFuture<Channel> {
+        let validPortRange = Int(UInt16.min)...Int(UInt16.max)
+        guard validPortRange.contains(port) else {
+            return self.group.next().makeFailedFuture(NIOTSErrors.InvalidPort(port: port))
+        }
+
         return self.bind0 { (channel, promise) in
             do {
                 // NWListener does not actually resolve hostname-based NWEndpoints

Tests/NIOTransportServicesTests/NIOTSBootstrapTests.swift

@@ -306,6 +306,33 @@ final class NIOTSBootstrapTests: XCTestCase {
                                    setValue: false,
                                    shortOption: .disableAutoRead)
     }
+
+    func testBootstrapsErrorGracefullyOnOutOfBandPorts() throws {
+        let invalidPortNumbers = [-1, 65536]
+
+        let group = NIOTSEventLoopGroup()
+        defer {
+            try! group.syncShutdownGracefully()
+        }
+
+        let listenerBootstrap = NIOTSListenerBootstrap(group: group)
+        let connectionBootstrap = NIOTSConnectionBootstrap(group: group)
+
+        for invalidPort in invalidPortNumbers {
+            var listenerChannel: Channel?
+            var connectionChannel: Channel?
+
+            XCTAssertThrowsError(listenerChannel = try listenerBootstrap.bind(host: "localhost", port: invalidPort).wait()) { error in
+                XCTAssertNotNil(error as? NIOTSErrors.InvalidPort)
+            }
+            XCTAssertThrowsError(connectionChannel = try connectionBootstrap.connect(host: "localhost", port: invalidPort).wait())  { error in
+                XCTAssertNotNil(error as? NIOTSErrors.InvalidPort)
+            }
+
+            try? listenerChannel?.close().wait()
+            try? connectionChannel?.close().wait()
+        }
+    }
 }
 
 extension Channel {