Fixed a bunch of errors related to inproper responses from webservers.

nselib/http.lua

@@ -2173,6 +2173,10 @@ end
 --
 -- @param body The body of the page.
 function clean_404(body)
+  if ( not(body) ) then
+    return
+  end
+
   -- Remove anything that looks like time
   body = string.gsub(body, '%d?%d:%d%d:%d%d', "")
   body = string.gsub(body, '%d%d:%d%d', "")

scripts/http-affiliate-id.nse

@@ -91,6 +91,10 @@ portaction = function(host, port)
 	local url_path = stdnse.get_script_args("http-affiliate-id.url-path") or "/"
 	local body = http.get(host, port, url_path).body
 
+	if ( not(body) ) then
+		return
+	end
+
 	-- Here goes affiliate matching
 	for name, re in pairs(AFFILIATE_PATTERNS) do
 		local regex = pcre.new(re, 0, "C")

scripts/http-generator.nse

@@ -78,6 +78,7 @@ action = function(host, port)
              end)
 
    response = follow_redirects(host, port, path, redirects)
-   return response.body:match(pattern)
-
+   if ( response and response.body ) then
+     return response.body:match(pattern)
+   end
 end

scripts/http-slowloris-check.nse

@@ -65,6 +65,10 @@ local TimeWith 	  -- time with additional headers
 
 -- does a half http request and waits until timeout 
 local function slowThread1(host,port)
+	-- if no response was received when determining SSL
+	if ( Bestopt == "none" ) then
+		return
+	end
 	local socket,status
 	local catch = function()
 		TimeWithout = nmap.clock()
@@ -81,6 +85,10 @@ end
 -- does a half http request but sends another 
 -- header value after 10 seconds
 local function slowThread2(host,port)
+	-- if no response was received when determining SSL
+	if ( Bestopt == "none" ) then
+		return
+	end
 	local socket,status
 	local catch = function()
 		-- note the time the socket timedout
@@ -135,6 +143,9 @@ so, it starves the http server's resources causing Denial Of Service.
 		stdnse.sleep(1)
 	end
 	-- compare times
+	if ( not(TimeWith) or not(TimeWithout) ) then
+		return
+	end
 	local diff = TimeWith - TimeWithout 
 	stdnse.print_debug("Time difference is: %d",diff)
 	-- if second connection died 10 or more seconds after the first 

scripts/http-title.nse

@@ -51,6 +51,10 @@ action = function(host, port)
     end
   end
 
+  if ( not(resp.body) ) then
+    return
+  end
+
   -- try and match title tags
   title = string.match(resp.body, "<[Tt][Ii][Tt][Ll][Ee][^>]*>([^<]*)</[Tt][Ii][Tt][Ll][Ee]>")
 

scripts/http-trace.nse

@@ -37,7 +37,9 @@ portrule = shortport.http
 --@param response_headers The HTTP response headers 
 local validate = function(response, response_headers)
   local output_lines = {}
-
+  if ( not(response) ) then
+    return
+  end
   if not(response:match("HTTP/1.[01] 200") or response:match("TRACE / HTTP/1.[01]")) then
     return
   else