Add basic template

Author: sangkilc

Diff for: .gitignore

@@ -0,0 +1,2 @@
+bin/
+obj/

Diff for: Dockerfile

@@ -0,0 +1,14 @@
+FROM mcr.microsoft.com/dotnet/core/sdk:3.1
+
+RUN apt-get update && apt-get install -y xinetd
+RUN mkdir -p /var/ctf /app
+COPY flag /var/ctf/
+COPY myservice /etc/xinetd.d/
+COPY Program.fs /app
+COPY *.fsproj /app
+
+RUN echo "myservice 4000/tcp" >> /etc/services
+RUN service xinetd restart
+
+WORKDIR /app
+CMD ["xinetd", "-dontfork"]

Diff for: Program.fs

@@ -0,0 +1,11 @@
+open System
+
+[<EntryPoint>]
+let main _argv =
+  Console.WriteLine "1 + 1 = ?"
+  Console.ReadLine ()
+  |> Convert.ToInt32
+  |> fun n ->
+    if n = 2 then IO.File.ReadAllText ("/var/ctf/flag") |> Console.WriteLine
+    else Console.WriteLine ()
+  0

Diff for: docker.fsproj

@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp3.1</TargetFramework>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Include="Program.fs" />
+  </ItemGroup>
+
+</Project>

Diff for: flag

@@ -0,0 +1 @@
+this is my flag

Diff for: myservice

@@ -0,0 +1,11 @@
+service myservice
+{
+  flags = REUSE
+  socket_type = stream
+  wait = no
+  user = root
+  server = /usr/bin/dotnet
+  server_args = run --project /app
+  disable = no
+  port = 4000
+}