Fix read_reply to use get_once correctly

Author: jvazquez-r7

modules/exploits/multi/misc/java_jdwp_debugger.rb

@@ -175,13 +175,30 @@ def create_packet(cmdsig, data="")
 
   # Reads packet response for JDWP protocol
   def read_reply(timeout = default_timeout)
-    response = sock.get(timeout)
+    length = sock.get_once(4, timeout)
+    fail_with(Failure::TimeoutExpired, "#{peer} - Not received response length") unless length
+    pkt_len = length.unpack('N')[0]
+    if pkt_len < 4
+      fail_with(Failure::Unknown, "#{peer} - Received corrupted response")
+    end
+    pkt_len = pkt_len - 4
+
+    response = sock.get_once(pkt_len, timeout)
     fail_with(Failure::TimeoutExpired, "#{peer} - Not received response") unless response
-    pktlen, id, flags, errcode = response.unpack('NNCn')
-    response.slice!(0..10)
-    if errcode != 0 && flags == REPLY_PACKET_TYPE
-      fail_with(Failure::Unknown, "#{peer} - Server sent error with code #{errcode}")
+    while response.length < pkt_len
+      partial = sock.get_once(pkt_len, timeout)
+      fail_with(Failure::TimeoutExpired, "#{peer} - Not received response") unless partial
+      response << partial
+    end
+
+    fail_with(Failure::Unknown, "#{peer} - Received corrupted response") unless response.length == pkt_len
+
+    id, flags, err_code = response.unpack('NCn')
+    response.slice!(0..6)
+    if err_code != 0 && flags == REPLY_PACKET_TYPE
+      fail_with(Failure::Unknown, "#{peer} - Server sent error with code #{err_code}")
     end
+
     response
   end