add a --no-srng command line option to disable...

...server-side RNG support to allow potential OoS debugging without
having to rebuild

src/game.cpp

@@ -442,6 +442,8 @@ game_controller::game_controller(int argc, char** argv) :
 #else
 			std::cerr << "Option --dummy-locales ignored: support was not compiled in.\n";
 #endif
+		} else if(val == "--no-srng") {
+			rand_rng::disable_server_rng();
 		} else if(val[0] == '-') {
 			std::cerr << "unknown option: " << val << std::endl;
 			throw config::error("unknown option");
@@ -1773,6 +1775,8 @@ static int process_command_args(int argc, char** argv) {
 			<< "  --nocache                    disables caching of game data.\n"
 			<< "  --nomusic                    runs the game without music.\n"
 			<< "  --nosound                    runs the game without sounds and music.\n"
+			<< "  --no-srng                    disable server-side RNG support (will cause OOS\n"
+			<< "                               errors unless every player uses it)\n"
 			<< "  --path                       prints the path to the data directory and exits.\n"
 			<< "  -r, --resolution XxY         sets the screen resolution. Example: -r 800x600\n"
 			<< "  --rng-seed <number>          seeds the random number generator with number\n"
@@ -1887,7 +1891,7 @@ static int process_command_args(int argc, char** argv) {
 				return 2;
 			}
 			srand(lexical_cast_default<unsigned int>(argv[arg]));
- 		}
+		}
 	}
 
 	// Not the most intuitive solution, but I wanted to leave current semantics for now

src/mouse_events.cpp

@@ -676,10 +676,10 @@ bool mouse_handler::attack_enemy_(unit_map::iterator attacker, unit_map::iterato
 
 		gui().draw();
 		recorder.add_attack(attacker_loc, defender_loc, att.attack_num, def.attack_num);
-		if (network::nconnections() == 0) {
+		rand_rng::invalidate_seed();
+		if (rand_rng::has_valid_seed()) { //means SRNG is disabled
 			perform_attack(attacker_loc, defender_loc, att.attack_num, def.attack_num, rand());
 		} else {
-			rand_rng::invalidate_seed();
 			rand_rng::set_new_seed_callback(boost::bind(&mouse_handler::perform_attack,
 				this, attacker_loc, defender_loc, att.attack_num, def.attack_num, _1));
 		}

src/random.cpp

@@ -57,6 +57,7 @@ namespace {
   rand_rng::seed_t last_seed;
   bool seed_valid = false;
   boost::function<void (rand_rng::seed_t)> new_seed_callback;
+  bool srng_disabled = false;
 }
 
 
@@ -107,8 +108,8 @@ void invalidate_seed()
 
 bool has_valid_seed()
 {
-	//in a SP game the seed is always valid
-	return (network::nconnections() == 0) || seed_valid;
+	//if the SRNG is disabled or we're in a SP game the seed is always valid
+	return srng_disabled || (network::nconnections() == 0) || seed_valid;
 }
 
 seed_t get_last_seed()
@@ -128,6 +129,11 @@ void clear_new_seed_callback()
 	new_seed_callback = NULL;
 }
 
+void disable_server_rng()
+{
+	srng_disabled = true;
+}
+
 
 
 rng::rng() : random_(NULL), random_child_(0), generator_()

src/rng.hpp

@@ -82,6 +82,12 @@ void set_new_seed_callback(boost::function<void (seed_t)> f);
  */
 void clear_new_seed_callback();
 
+/**
+ * Disable server RNG support, will cause OOS if playing MP with a client with
+ * SRNG enabled. For debugging purposes, should be removed before 1.8.0
+ */
+void disable_server_rng();
+
 } // ends rand_rng namespace
 
 #endif