Specify host port when different from scheme default port (#358)

* Specify host port when different from scheme default port

When port is not the same as the standard port for the scheme, it should be specified (https://tools.ietf.org/html/rfc2616#section-14.23)

* Add comment to explain why we specify host port

* Rename host to hostHeaderValue

Author: Trevör

Sources/HTTPKit/Client/HTTPClient.swift

@@ -69,7 +69,8 @@ public final class HTTPClient {
 
     public func send(_ request: HTTPRequest) -> EventLoopFuture<HTTPResponse> {
         let hostname = request.url.host ?? ""
-        let port = request.url.port ?? (request.url.scheme == "https" ? 443 : 80)
+        let defaultSchemePort = request.url.scheme == "https" ? 443 : 80
+        let port = request.url.port ?? defaultSchemePort
         let tlsConfig: TLSConfiguration?
         switch request.url.scheme {
         case "https":
@@ -139,7 +140,16 @@ public final class HTTPClient {
             handlers.append(("client-decoder", clientResDecoder))
             httpHandlerNames.append("client-decoder")
 
-            let clientReqEncoder = HTTPClientRequestEncoder(hostname: hostname)
+            // When port is different from the default port for the scheme
+            // it must be explicitly specified in the `Host` HTTP header.
+            // See https://tools.ietf.org/html/rfc2616#section-14.23
+            let clientReqEncoder: HTTPClientRequestEncoder
+            if port == defaultSchemePort {
+                clientReqEncoder = HTTPClientRequestEncoder(hostHeaderValue: hostname)
+            } else {
+                clientReqEncoder = HTTPClientRequestEncoder(hostHeaderValue: "\(hostname):\(port)")
+            }
+            
             handlers.append(("client-encoder", clientReqEncoder))
             httpHandlerNames.append("client-encoder")
 

Sources/HTTPKit/Client/HTTPClientRequestEncoder.swift

@@ -3,18 +3,18 @@ internal final class HTTPClientRequestEncoder: ChannelOutboundHandler, Removable
     typealias OutboundIn = HTTPRequest
     typealias OutboundOut = HTTPClientRequestPart
 
-    let hostname: String
+    let hostHeaderValue: String
 
     /// Creates a new `HTTPClientRequestSerializer`.
-    init(hostname: String) {
-        self.hostname = hostname
+    init(hostHeaderValue: String) {
+        self.hostHeaderValue = hostHeaderValue
     }
 
     /// See `ChannelOutboundHandler`.
     func write(context: ChannelHandlerContext, data: NIOAny, promise: EventLoopPromise<Void>?) {
         let req = unwrapOutboundIn(data)
         var headers = req.headers
-        headers.add(name: .host, value: self.hostname)
+        headers.add(name: .host, value: self.hostHeaderValue)
 
         let path: String
         if let query = req.url.query {