Catch Zenmap's MemoryError (caused by large Nmap Output) and provide the user a more useful error message so that we get less of the out-of-memory "crash reports"

todo/done.txt

@@ -1,5 +1,13 @@
 DONE:
 
+o In an ideal world, Zenmap would not run out of memory and crash.
+  And we already have an entry for improving Zenmap's memory
+  consumption.  But in the meantime, we should catch the error and
+  present a more useful error message/explanation so the user
+  understands the problem.  This should reduce the number of
+  out-of-memory "crash reports" we get too.  See
+  http://seclists.org/nmap-dev/2014/q2/298
+
 o Provide an option to send a comment in scan packet data for target
   network.  Examples: --data-string "Scan conducted by Marc Reis from
   SecOps, extension 2147" or --data-string "pH33r my l3eT

todo/nmap.txt

@@ -55,13 +55,6 @@ o GSOC 2014 student Jay will be looking at these items:
     commonly get error reports from people who load so many systems that
     Zenmap gives an out of memory error and crashes.  For example, see
     this thread: http://seclists.org/nmap-dev/2014/q2/46
-  o In an ideal world, Zenmap would not run out of memory and crash.
-    And we already have an entry for improving Zenmap's memory
-    consumption.  But in the meantime, we should catch the error and
-    present a more useful error message/explanation so the user
-    understands the problem.  This should reduce the number of
-    out-of-memory "crash reports" we get too.  See
-    http://seclists.org/nmap-dev/2014/q2/298
   o Consider using a binary decision diagram for --exclude list to make
     it more efficient for large exclude lists.  See
     http://seclists.org/nmap-dev/2012/q4/420.

zenmap/zenmapGUI/NmapOutputViewer.py

@@ -296,8 +296,11 @@ class NmapOutputViewer (gtk.VBox):
 
     def show_nmap_output(self, output):
         """Show the string (or unicode) output in the output display."""
-        self.text_view.get_buffer().set_text(output)
-        self.apply_highlighting()
+        try:
+            self.text_view.get_buffer().set_text(output)
+            self.apply_highlighting()
+        except MemoryError:
+            self.show_large_output_message(self.command_execution)
 
     def set_command_execution(self, command):
         """Set the live running command whose output is shown by this display.
@@ -310,6 +313,31 @@ class NmapOutputViewer (gtk.VBox):
             self.output_file_pointer = None
         self.refresh_output()
 
+    def show_large_output_message(self, command=None):
+        buf = self.text_view.get_buffer()
+        try:
+            running = (command is not None and command.scan_state() is True)
+        except:
+            running = False
+            complete = False
+        else:
+            complete = not running
+        if running:
+            buf.set_text("Warning: You have insufficient resources for Zenmap "
+                "to be able to display the complete output from Nmap here. \n"
+                "Zenmap will continue to run the scan to completion. However,"
+                " some features of Zenmap might not work as expected.")
+        elif complete:
+            buf.set_text("Warning: You have insufficient resources for Zenmap "
+                "to be able to display the complete output from Nmap here. \n"
+                "The scan has completed. However, some features of Zenmap "
+                "might not work as expected.")
+        else:
+            buf.set_text("Warning: You have insufficient resources for Zenmap "
+                "to be able to display the complete output from Nmap here. \n"
+                "The scan has been stopped. Some features of Zenmap might not "
+                "work as expected.")
+
     def refresh_output(self, widget=None):
         """Update the output from the latest output of the command associated
         with this view, as set by set_command_execution. It has no effect if no
@@ -322,7 +350,13 @@ class NmapOutputViewer (gtk.VBox):
         # Seek to the end of the most recent read.
         self.command_execution.stdout_file.seek(self.output_file_pointer)
         pos = self.command_execution.stdout_file.tell()
-        new_output = self.command_execution.stdout_file.read()
+
+        try:
+            new_output = self.command_execution.stdout_file.read()
+        except MemoryError:
+            self.show_large_output_message(self.command_execution)
+            return
+
         self.output_file_pointer = self.command_execution.stdout_file.tell()
         # print "read %d -> %d %d" % (
         #         pos, self.output_file_pointer, len(new_output))
@@ -335,10 +369,14 @@ class NmapOutputViewer (gtk.VBox):
             buf = self.text_view.get_buffer()
             prev_end_mark = buf.create_mark(
                     None, buf.get_end_iter(), left_gravity=True)
-            buf.insert(buf.get_end_iter(), new_output)
-            # Highlight the new text.
-            self.apply_highlighting(
-                    buf.get_iter_at_mark(prev_end_mark), buf.get_end_iter())
+            try:
+                buf.insert(buf.get_end_iter(), new_output)
+                # Highlight the new text.
+                self.apply_highlighting(
+                        buf.get_iter_at_mark(prev_end_mark), buf.get_end_iter())
+            except MemoryError:
+                self.show_large_output_message(self.command_execution)
+                return
 
             if at_end:
                 # If we were already scrolled to the bottom, scroll back to the

zenmap/zenmapGUI/ScanInterface.py

@@ -654,7 +654,10 @@ class ScanInterface(HIGVBox):
                 warn_dialog.destroy()
         parsed.set_xml_is_temp(command.xml_is_temp)
         self.collect_umit_info(command, parsed)
-        parsed.nmap_output = command.get_output()
+        try:
+            parsed.nmap_output = command.get_output()
+        except MemoryError:
+            self.scan_result.scan_result_notebook.nmap_output.nmap_output.show_large_output_message(command)
         self.update_ui()
         self.scans_store.finish_running_scan(command, parsed)