Improve the HTTP implementation

This commit adds support for:

* Version negotiation.
* HEAD requests.
* Friendly error messages.
* More robust reference counting.

Signed-off-by: Graham <gpe@openrs2.org>

game/src/main/kotlin/org/openrs2/game/net/crossdomain/CrossDomainChannelHandler.kt

@@ -1,14 +1,13 @@
 package org.openrs2.game.net.crossdomain
 
 import io.netty.buffer.Unpooled
-import io.netty.channel.ChannelFutureListener
 import io.netty.channel.ChannelHandler
 import io.netty.channel.ChannelHandlerContext
 import io.netty.channel.SimpleChannelInboundHandler
-import io.netty.handler.codec.http.HttpHeaderNames
 import io.netty.handler.codec.http.HttpMethod
 import io.netty.handler.codec.http.HttpRequest
 import io.netty.handler.codec.http.HttpResponseStatus
+import org.openrs2.buffer.use
 import org.openrs2.game.net.http.Http
 
 @ChannelHandler.Sharable
@@ -29,15 +28,13 @@ public object CrossDomainChannelHandler : SimpleChannelInboundHandler<HttpReques
 
     override fun channelRead0(ctx: ChannelHandlerContext, msg: HttpRequest) {
         if (msg.method() != HttpMethod.GET || msg.uri() != ENDPOINT) {
-            ctx.write(Http.createResponse(HttpResponseStatus.BAD_REQUEST)).addListener(ChannelFutureListener.CLOSE)
+            Http.writeResponse(ctx, msg, HttpResponseStatus.BAD_REQUEST)
             return
         }
 
-        val response = Http.createResponse(HttpResponseStatus.OK)
-        response.headers().add(HttpHeaderNames.CONTENT_TYPE, Http.TEXT_X_CROSS_DOMAIN_POLICY)
-        response.headers().add(HttpHeaderNames.CONTENT_LENGTH, POLICY.size)
-        ctx.write(response, ctx.voidPromise())
-        ctx.write(Unpooled.wrappedBuffer(POLICY)).addListener(ChannelFutureListener.CLOSE)
+        Unpooled.wrappedBuffer(POLICY).use { buf ->
+            Http.writeResponse(ctx, msg, buf, Http.TEXT_X_CROSS_DOMAIN_POLICY)
+        }
     }
 
     override fun channelReadComplete(ctx: ChannelHandlerContext) {

game/src/main/kotlin/org/openrs2/game/net/http/Http.kt

@@ -1,20 +1,91 @@
 package org.openrs2.game.net.http
 
+import io.netty.buffer.ByteBuf
+import io.netty.channel.ChannelFutureListener
+import io.netty.channel.ChannelHandlerContext
+import io.netty.channel.FileRegion
 import io.netty.handler.codec.http.DefaultHttpResponse
 import io.netty.handler.codec.http.HttpHeaderNames
 import io.netty.handler.codec.http.HttpHeaderValues
-import io.netty.handler.codec.http.HttpResponse
+import io.netty.handler.codec.http.HttpMethod
+import io.netty.handler.codec.http.HttpRequest
 import io.netty.handler.codec.http.HttpResponseStatus
 import io.netty.handler.codec.http.HttpVersion
+import io.netty.util.ReferenceCounted
+import org.openrs2.buffer.copiedBuffer
+import org.openrs2.buffer.use
 
 public object Http {
     public const val MAX_CONTENT_LENGTH: Int = 65536
     public const val TEXT_X_CROSS_DOMAIN_POLICY: String = "text/x-cross-domain-policy"
+    private const val BANNER = "OpenRS2"
 
-    public fun createResponse(status: HttpResponseStatus): HttpResponse {
-        val response = DefaultHttpResponse(HttpVersion.HTTP_1_1, status)
+    private fun writeResponse(
+        ctx: ChannelHandlerContext,
+        request: HttpRequest,
+        status: HttpResponseStatus,
+        content: ReferenceCounted,
+        contentType: CharSequence,
+        contentLength: Long
+    ) {
+        val version = if (request.protocolVersion() == HttpVersion.HTTP_1_0) {
+            HttpVersion.HTTP_1_0
+        } else {
+            HttpVersion.HTTP_1_1
+        }
+
+        val response = DefaultHttpResponse(version, status)
         response.headers().add(HttpHeaderNames.CONNECTION, HttpHeaderValues.CLOSE)
-        response.headers().add(HttpHeaderNames.SERVER, "OpenRS2")
-        return response
+        response.headers().add(HttpHeaderNames.SERVER, BANNER)
+        response.headers().add(HttpHeaderNames.CONTENT_TYPE, contentType)
+        response.headers().add(HttpHeaderNames.CONTENT_LENGTH, contentLength)
+
+        if (request.method() == HttpMethod.HEAD) {
+            ctx.write(response).addListener(ChannelFutureListener.CLOSE)
+        } else {
+            ctx.write(response, ctx.voidPromise())
+            ctx.write(content.retain()).addListener(ChannelFutureListener.CLOSE)
+        }
+    }
+
+    public fun writeResponse(
+        ctx: ChannelHandlerContext,
+        request: HttpRequest,
+        content: ByteBuf,
+        contentType: CharSequence
+    ) {
+        writeResponse(ctx, request, HttpResponseStatus.OK, content, contentType, content.readableBytes().toLong())
+    }
+
+    public fun writeResponse(
+        ctx: ChannelHandlerContext,
+        request: HttpRequest,
+        content: FileRegion,
+        contentType: CharSequence
+    ) {
+        writeResponse(ctx, request, HttpResponseStatus.OK, content, contentType, content.count())
+    }
+
+    public fun writeResponse(ctx: ChannelHandlerContext, request: HttpRequest, status: HttpResponseStatus) {
+        copiedBuffer(
+            """
+            <!DOCTYPE html>
+            <html lang="en">
+                <head>
+                    <meta charset="UTF-8" />
+                    <title>$status</title>
+                </head>
+                <body>
+                    <center>
+                        <h1>$status</h1>
+                    </center>
+                    <hr />
+                    <center>$BANNER</center>
+                </body>
+            </html>
+        """.trimIndent().plus("\n"), Charsets.UTF_8
+        ).use { buf ->
+            writeResponse(ctx, request, status, buf, HttpHeaderValues.TEXT_HTML, buf.readableBytes().toLong())
+        }
     }
 }

game/src/main/kotlin/org/openrs2/game/net/http/HttpChannelHandler.kt

@@ -1,13 +1,12 @@
 package org.openrs2.game.net.http
 
-import io.netty.channel.ChannelFutureListener
 import io.netty.channel.ChannelHandler
 import io.netty.channel.ChannelHandlerContext
 import io.netty.channel.SimpleChannelInboundHandler
-import io.netty.handler.codec.http.HttpHeaderNames
 import io.netty.handler.codec.http.HttpHeaderValues
 import io.netty.handler.codec.http.HttpRequest
 import io.netty.handler.codec.http.HttpResponseStatus
+import org.openrs2.buffer.use
 import org.openrs2.game.net.FileProvider
 import javax.inject.Inject
 import javax.inject.Singleton
@@ -24,22 +23,18 @@ public class HttpChannelHandler @Inject constructor(
     override fun channelRead0(ctx: ChannelHandlerContext, msg: HttpRequest) {
         val uri = msg.uri()
         if (!uri.startsWith("/")) {
-            ctx.write(Http.createResponse(HttpResponseStatus.BAD_REQUEST)).addListener(ChannelFutureListener.CLOSE)
+            Http.writeResponse(ctx, msg, HttpResponseStatus.BAD_REQUEST)
             return
         }
 
-        val file = fileProvider.get(uri.substring(1))
-        if (file == null) {
-            ctx.write(Http.createResponse(HttpResponseStatus.NOT_FOUND)).addListener(ChannelFutureListener.CLOSE)
-            return
-        }
+        fileProvider.get(uri.substring(1)).use { file ->
+            if (file == null) {
+                Http.writeResponse(ctx, msg, HttpResponseStatus.NOT_FOUND)
+                return
+            }
 
-        val response = Http.createResponse(HttpResponseStatus.OK)
-        response.headers().add(HttpHeaderNames.CONTENT_TYPE, HttpHeaderValues.APPLICATION_OCTET_STREAM)
-        response.headers().add(HttpHeaderNames.CONTENT_LENGTH, file.count())
-
-        ctx.write(response, ctx.voidPromise())
-        ctx.write(file).addListener(ChannelFutureListener.CLOSE)
+            Http.writeResponse(ctx, msg, file, HttpHeaderValues.APPLICATION_OCTET_STREAM)
+        }
     }
 
     override fun channelReadComplete(ctx: ChannelHandlerContext) {