- client: when emerge from bandwidth quota network suspension,

add 0..1hr random delay to existing transfers,
    to avoid DDOS effect

svn path=/trunk/boinc/; revision=21415

checkin_notes

@@ -3379,3 +3379,14 @@ David  7 May 2010
 		WelcomePage.cpp
 	lib/
 		str_util.cpp,h
+
+David  7 May 2010
+    - client: when emerge from bandwidth quota network suspension,
+        add 0..1hr random delay to existing transfers,
+        to avoid DDOS effect
+
+    db/
+        boinc_db.cpp
+    client/
+        client_state.cpp
+        pers_file_xfer.cpp,h

client/client_state.cpp

@@ -679,6 +679,13 @@ bool CLIENT_STATE::poll_slow_events() {
                 msg_printf(NULL, MSG_INFO, "Resuming file transfers");
             }
         }
+
+        // if we're emerging from a bandwidth quota suspension,
+        // add a random delay to avoid DDOS effect
+        //
+        if (old_network_suspend_reason == SUSPEND_REASON_NETWORK_QUOTA_EXCEEDED) {
+            pers_file_xfers->add_random_delay(3600);
+        }
     }
 
     // NOTE:

client/pers_file_xfer.cpp

@@ -30,6 +30,7 @@
 #include "error_numbers.h"
 #include "md5_file.h"
 #include "parse.h"
+#include "util.h"
 #include "str_util.h"
 #include "filesys.h"
 
@@ -513,9 +514,20 @@ int PERS_FILE_XFER_SET::remove(PERS_FILE_XFER* pfx) {
 //
 void PERS_FILE_XFER_SET::suspend() {
     unsigned int i;
-
     for (i=0; i<pers_file_xfers.size(); i++) {
         pers_file_xfers[i]->suspend();
     }
 }
 
+// add a random delay 0..x to all transfers
+// (used when emerging from bandwidth quota suspension)
+//
+void PERS_FILE_XFER_SET::add_random_delay(double x) {
+    unsigned int i;
+    for (i=0; i<pers_file_xfers.size(); i++) {
+        double y = gstate.now + x*drand();
+        if (y > pers_file_xfers[i]->next_request_time) {
+            pers_file_xfers[i]->next_request_time = y;
+        }
+    }
+}

client/pers_file_xfer.h

@@ -125,6 +125,7 @@ public:
     int remove(PERS_FILE_XFER*);
     bool poll();
     void suspend();
+    void add_random_delay(double);
 };
 
 #endif

db/boinc_db.cpp

@@ -2042,7 +2042,7 @@ int DB_SCHED_RESULT_ITEM_SET::update_workunits() {
 
 void DB_FILE::db_print(char* buf){
     snprintf(buf, MAX_QUERY_LEN,
-        "name='%s', md5sum=%s, size=%.15e",
+        "name='%s', md5sum='%s', size=%.15e",
         name, md5sum, size
     );
 }