Add example-shttp-fileserver (#156)

Add example for simple fileserver that lists/serves all files under the
current working directory.

Makefile

@@ -17,7 +17,7 @@ build: scion-bat \
 	scion-sensorfetcher scion-sensorserver \
 	scion-ssh scion-sshd \
 	example-helloworld \
-	example-shttp-client example-shttp-server example-shttp-proxy
+	example-shttp-client example-shttp-server example-shttp-fileserver example-shttp-proxy
 
 clean:
 	go clean ./...
@@ -98,6 +98,10 @@ example-shttp-client:
 example-shttp-server:
 	go build -o $(BIN)/$@ ./_examples/shttp/server
 
+.PHONY: example-shttp-fileserver
+example-shttp-fileserver:
+	go build -o $(BIN)/$@ ./_examples/shttp/fileserver
+
 .PHONY: example-shttp-proxy
 example-shttp-proxy:
 	go build -o $(BIN)/$@ ./_examples/shttp/proxy

_examples/shttp/fileserver/main.go

@@ -0,0 +1,34 @@
+// Copyright 2020 ETH Zurich
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// example-shttp-fileserver is a simple HTTP fileserver that serves all files
+// and subdirectories under the current working directory.
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"net/http"
+
+	"github.com/netsec-ethz/scion-apps/pkg/shttp"
+)
+
+func main() {
+	port := flag.Uint("p", 443, "port the server listens on")
+	flag.Parse()
+
+	handler := http.FileServer(http.Dir(""))
+	log.Fatal(shttp.ListenAndServe(fmt.Sprintf(":%d", *port), handler, nil))
+}