FTP overhaul: better SSL connection, including ftp-anon over ftps or STARTTLS

nselib/ftp.lua

@@ -14,28 +14,59 @@ local ERROR_MESSAGES = {
   ["ERROR"]   = "failed to receive data"
 }
 
---- Connects to the FTP server based on the provided options.
+local crlf_pattern = "\r?\n"
+--- Connects to the FTP server based on the provided options and returns the parsed banner.
 --
 -- @param host The host table
 -- @param port The port table
--- @param opts The connection option table, possible options:
---    timeout: generic timeout value
---    recv_before: receive data before returning
+-- @param opts The connection option table, from comm.lua.
 -- @return socket The socket descriptor, or nil on errors
--- @return response The response received on success and when
---    the recv_before is set, or the error message on failures.
+-- @return code The numeric response code, as returned by read_reply, or error message if socket is nil.
+-- @return message The response message
+-- @return buffer The socket read buffer function, to be passed to read_reply.
+-- @see comm.lua
 connect = function(host, port, opts)
-  local socket, _, _, ret = comm.tryssl(host, port, '', opts)
+  opts = opts or {}
+  opts.recv_before = true
+  local socket, err, proto, ret = comm.tryssl(host, port, '', opts)
   if not socket then
     return socket, (ERROR_MESSAGES[ret] or 'unspecified error')
   end
-  return socket, ret
+  local buffer = stdnse.make_buffer(socket, crlf_pattern)
+  local pos = 1
+  -- Should we just pass the output of buffer()?
+  local usebuf = false
+  -- Since we already read the first chunk of banner from the socket,
+  -- we have to supply it line-by-line to read_reply.
+  local code, message = read_reply(function()
+      if usebuf then
+        -- done reading the initial banner; pass along the socket buffer.
+        return buffer()
+      end
+      -- Look for CRLF
+      local i, j = ret:find(crlf_pattern, pos)
+      if not i then
+        -- Didn't find it! Grab another chunk (up to CRLF) and return it
+        usebuf = true
+        local chunk = buffer()
+        return ret:sub(pos) .. chunk
+      end
+      local oldpos = pos
+      -- start the next search just after CRLF
+      pos = j + 1
+      if pos >= #ret then
+        -- We consumed the whole thing! Start calling buffer() next.
+        usebuf = true
+      end
+      return ret:sub(oldpos, i - 1)
+    end)
+  return socket, code, message, buffer
 end
 
 ---
 -- Read an FTP reply and return the numeric code and the message. See RFC 959,
 -- section 4.2.
--- @param buffer should have been created with
+-- @param buffer The buffer returned by ftp.connect or created with
 -- <code>stdnse.make_buffer(socket, "\r?\n")</code>.
 -- @return numeric code or <code>nil</code>.
 -- @return text reply or error message.