check for a nil return value from write(), fixes #4329

git-svn-id: file:///home/svn/framework3/trunk@12528 4d416f70-5f16-0410-b530-b9f4589650da

lib/rex/io/stream_abstraction.rb

@@ -148,7 +148,6 @@ protected
 							closed = true
 							wlog("monitor_rsock: closed remote socket due to nil read")
 						end
-
 					rescue ::Exception
 						closed = true
 						wlog("monitor_rsock: exception during read: #{e.class} #{e}")
@@ -170,10 +169,13 @@ protected
 							#     This way we naturally perform a resend if a failure occured.
 							#     Catches an edge case with meterpreter TCP channels where remote send
 							#     failes gracefully and a resend is required.
-							if( sent > 0 )
+							if (sent.nil? or sent <= 0)
+								wlog("monitor_rsock: failed writing, socket must be dead")
+								break
+							else
 								total_sent += sent
 							end
-						rescue ::IOError => e
+						rescue ::IOError, ::EOFError => e
 							closed = true
 							wlog("monitor_rsock: exception during write: #{e.class} #{e}")
 							break