[ruby/net-ftp] Close the passive connection data socket if there is an error setting up the transfer

Previously, the connection leaked in this case.  This uses
begin/ensure and checking for an error in the ensure block.

An alternative approach would be to not even perform the
connection until after the RETR (or other) command has been
sent.  However, I'm not sure all FTP servers support that.
The current behavior is:

* Send (PASV/EPSV)
* Connect to the host/port returned in 227/229 reply
* Send (RETR/other command)

Changing it to connect after the RETR could break things.
FTP servers might expect that the client has already
connected before sending the RETR.  The alternative
approach is more likely to introduce backwards compatibility
issues, compared to the begin/ensure approach taken here.

Fixes Ruby Bug 17027

https://github.com/ruby/net-ftp/commit/6e8535f076

lib/net/ftp.rb

@@ -547,18 +547,22 @@ module Net
     def transfercmd(cmd, rest_offset = nil) # :nodoc:
       if @passive
         host, port = makepasv
-        conn = open_socket(host, port)
-        if @resume and rest_offset
-          resp = sendcmd("REST " + rest_offset.to_s)
-          if !resp.start_with?("3")
+        begin
+          conn = open_socket(host, port)
+          if @resume and rest_offset
+            resp = sendcmd("REST " + rest_offset.to_s)
+            if !resp.start_with?("3")
+              raise FTPReplyError, resp
+            end
+          end
+          resp = sendcmd(cmd)
+          # skip 2XX for some ftp servers
+          resp = getresp if resp.start_with?("2")
+          if !resp.start_with?("1")
             raise FTPReplyError, resp
           end
-        end
-        resp = sendcmd(cmd)
-        # skip 2XX for some ftp servers
-        resp = getresp if resp.start_with?("2")
-        if !resp.start_with?("1")
-          raise FTPReplyError, resp
+        ensure
+          conn.close if conn && $!
         end
       else
         sock = makeport

test/net/ftp/test_ftp.rb

@@ -882,6 +882,41 @@ class FTPTest < Test::Unit::TestCase
     end
   end
 
+  def test_getbinaryfile_error
+    commands = []
+    binary_data = ""
+    server = create_ftp_server { |sock|
+      sock.print("220 (test_ftp).\r\n")
+      commands.push(sock.gets)
+      sock.print("331 Please specify the password.\r\n")
+      commands.push(sock.gets)
+      sock.print("230 Login successful.\r\n")
+      commands.push(sock.gets)
+      sock.print("200 Switching to Binary mode.\r\n")
+      line = sock.gets
+      commands.push(line)
+      sock.print("450 No Dice\r\n")
+    }
+    begin
+      begin
+        ftp = Net::FTP.new
+        ftp.passive = true
+        ftp.read_timeout *= 5 if defined?(RubyVM::MJIT) && RubyVM::MJIT.enabled? # for --jit-wait
+        ftp.connect(SERVER_ADDR, server.port)
+        ftp.login
+        assert_match(/\AUSER /, commands.shift)
+        assert_match(/\APASS /, commands.shift)
+        assert_equal("TYPE I\r\n", commands.shift)
+        assert_raise(Net::FTPTempError) {ftp.getbinaryfile("foo", nil)}
+        assert_match(/\A(PASV|EPSV)\r\n/, commands.shift)
+      ensure
+        ftp.close if ftp
+      end
+    ensure
+      server.close
+    end
+  end
+
   def test_storbinary
     commands = []
     binary_data = (0..0xff).map {|i| i.chr}.join * 4 * 3
@@ -1935,7 +1970,7 @@ EOF
         assert_equal(nil, commands.shift)
         # FIXME: The new_session_cb is known broken for clients in OpenSSL 1.1.0h.
         # See https://github.com/openssl/openssl/pull/5967 for details.
-        if OpenSSL::OPENSSL_LIBRARY_VERSION !~ /OpenSSL 1.1.0h/
+        if OpenSSL::OPENSSL_LIBRARY_VERSION !~ /OpenSSL 1.1.0h|LibreSSL/
           assert_equal(true, session_reused_for_data_connection)
         end
       ensure
@@ -2019,7 +2054,7 @@ EOF
         assert_equal("RETR foo\r\n", commands.shift)
         assert_equal(nil, commands.shift)
         # FIXME: The new_session_cb is known broken for clients in OpenSSL 1.1.0h.
-        if OpenSSL::OPENSSL_LIBRARY_VERSION !~ /OpenSSL 1.1.0h/
+        if OpenSSL::OPENSSL_LIBRARY_VERSION !~ /OpenSSL 1.1.0h|LibreSSL/
           assert_equal(true, session_reused_for_data_connection)
         end
       ensure