Factor common code out of fake destinations

tests/flexnbd/fake_dest.rb

@@ -0,0 +1,51 @@
+# encoding: utf-8
+
+require 'socket'
+require 'timeout'
+
+require 'flexnbd/constants'
+
+module FlexNBD
+  module FakeDest
+
+    def serve( addr, port )
+      TCPServer.new( addr, port )
+    end
+
+
+    def accept( sock, err_msg, timeout=2 )
+      client_sock = nil
+
+      begin
+        Timeout.timeout(timeout) do
+          client_sock = sock.accept
+        end
+      rescue Timeout::Error
+        $stderr.puts err_msg
+        exit 1
+      end
+
+      client_sock
+    end
+
+
+    def write_hello( client_sock, opts={} )
+      client_sock.write( "NBDMAGIC" )
+
+      if opts[:magic] == :wrong
+        client_sock.write( "\x00\x00\x42\x02\x81\x86\x12\x52" )
+      else
+        client_sock.write( "\x00\x00\x42\x02\x81\x86\x12\x53" )
+      end
+
+      if opts[:size] == :wrong
+        8.times do client_sock.write rand(256).chr end
+      else
+        client_sock.write( "\x00\x00\x00\x00\x00\x00\x10\x00" )
+      end
+
+      client_sock.write( "\x00" * 128 )
+    end
+
+  end
+end # module FlexNBD