add static fileserver

zio-http/src/main/scala/zio/http/StaticServe.scala

@@ -0,0 +1,88 @@
+package zio.http
+
+import java.io.File
+
+import zio.ZIO
+
+import zio.http.codec.{PathCodec, SegmentCodec}
+
+sealed trait StaticServe[-R, +E, -I, +A] { self =>
+
+  def run(path: Path): Handler[R, E, I, A]
+
+  def orElse[R1 <: R, E1, I1 <: I, A1 >: A](that: => StaticServe[R1, E1, I1, A1]): StaticServe[R1, E1, I1, A1] =
+    StaticServe.run { path =>
+      self.run(path).orElse(that.run(path))
+    }
+
+}
+
+object StaticServe {
+
+  def run[R, E, I, A](f: Path => Handler[R, E, I, A]): StaticServe[R, E, I, A] =
+    new StaticServe[R, E, I, A] {
+      override def run(path: Path) = f(path)
+    }
+
+  def fromFileZIO[R](zio: => ZIO[R, Throwable, File]): StaticServe[R, Throwable, Any, Response] = run { _ =>
+    Handler.fromFileZIO(zio)
+  }
+
+  def fromDirectory(docRoot: File): StaticServe[Any, Throwable, Any, Response] = run { path =>
+    val target = new File(docRoot.getAbsolutePath() + path.encode)
+    if (target.getCanonicalPath.startsWith(docRoot.getCanonicalPath)) Handler.fromFile(target)
+    else {
+      Handler.fromZIO(
+        ZIO.logWarning(s"attempt to access file outside of docRoot: ${target.getAbsolutePath}"),
+      ) *> Handler.badRequest
+    }
+  }
+
+  def fromDirectory(docRoot: String): StaticServe[Any, Throwable, Any, Response] =
+    fromDirectory(new File(docRoot))
+
+  def fromResource: StaticServe[Any, Throwable, Any, Response] = run { path =>
+    Handler.fromResource(path.dropLeadingSlash.encode)
+  }
+
+  private def middleware[R, E](
+    mountpoint: RoutePattern[_],
+    staticServe: StaticServe[R, E, Any, Response],
+  ): Middleware[R] =
+    new Middleware[R] {
+
+      private def checkFishy(acc: Boolean, segment: String): Boolean = {
+        val stop = segment.indexOf('/') >= 0 || segment.indexOf('\\') >= 0 || segment == ".."
+        acc || stop
+      }
+
+      override def apply[Env1 <: R, Err](routes: Routes[Env1, Err]): Routes[Env1, Err] = {
+        val pattern = mountpoint / trailing
+        val other   = Routes(
+          pattern -> Handler
+            .identity[Request]
+            .flatMap { request =>
+              val isFishy = request.path.segments.foldLeft(false)(checkFishy)
+              if (isFishy) {
+                Handler.fromZIO(ZIO.logWarning(s"fishy request detected: ${request.path.encode}")) *> Handler.badRequest
+              } else {
+                val segs   = pattern.pathCodec.segments.collect { case SegmentCodec.Literal(v, _) =>
+                  v
+                }
+                val unnest = segs.foldLeft(Path.empty)(_ / _).addLeadingSlash
+                val path   = request.path.unnest(unnest).addLeadingSlash
+                staticServe.run(path).sandbox
+              }
+            },
+        )
+        routes ++ other
+      }
+    }
+
+  def middleware[R, E](path: Path, staticServe: StaticServe[R, E, Any, Response]): Middleware[R] =
+    middleware(
+      Method.GET / path.segments.map(PathCodec.literal).reduceLeft(_ / _),
+      staticServe,
+    )
+
+}