Fix inconsistencies in random number generation.

The srand()/rand() interface was being intermixed with the
srandom()/random() one.  The later is now used throughout.

Changed the srand() and rand() BIFs to work deterministically if Bro
was given a seed file (addresses #825).  They also now wrap the
system's srandom() and random() instead of srand() and rand() as per
the above.

src/bro.bif

@@ -972,12 +972,12 @@ function sha256_hash_finish%(index: any%): string
 ##
 ## .. note::
 ##
-##      This function is a wrapper about the function ``rand`` provided by
+##      This function is a wrapper about the function ``random``
-##      the OS.
+##      provided by the OS.
 function rand%(max: count%): count
 	%{
 	int result;
-	result = bro_uint_t(double(max) * double(rand()) / (RAND_MAX + 1.0));
+	result = bro_uint_t(double(max) * double(bro_random()) / (RAND_MAX + 1.0));
 	return new Val(result, TYPE_COUNT);
 	%}
 
@@ -989,11 +989,11 @@ function rand%(max: count%): count
 ##
 ## .. note::
 ##
-##      This function is a wrapper about the function ``srand`` provided
+##      This function is a wrapper about the function ``srandom``
-##      by the OS.
+##      provided by the OS.
 function srand%(seed: count%): any
 	%{
-	srand(seed);
+	bro_srandom(seed);
 	return 0;
 	%}
 

src/input/readers/Benchmark.cc

@@ -59,7 +59,7 @@ string Benchmark::RandomString(const int len)
 	"abcdefghijklmnopqrstuvwxyz";
 
 	for (int i = 0; i < len; ++i)
-		s[i] = values[rand() / (RAND_MAX / sizeof(values))];
+		s[i] = values[random() / (RAND_MAX / sizeof(values))];
 
 	return s;
 	}
@@ -134,7 +134,7 @@ threading::Value* Benchmark::EntryToVal(TypeTag type, TypeTag subtype)
 		break;
 
 	case TYPE_INT:
-		val->val.int_val = rand();
+		val->val.int_val = random();
 		break;
 
 	case TYPE_TIME:
@@ -148,11 +148,11 @@ threading::Value* Benchmark::EntryToVal(TypeTag type, TypeTag subtype)
 
 	case TYPE_COUNT:
 	case TYPE_COUNTER:
-		val->val.uint_val = rand();
+		val->val.uint_val = random();
 		break;
 
 	case TYPE_PORT:
-		val->val.port_val.port = rand() / (RAND_MAX / 60000);
+		val->val.port_val.port = random() / (RAND_MAX / 60000);
 		val->val.port_val.proto = TRANSPORT_UNKNOWN;
 		break;
 
@@ -175,7 +175,7 @@ threading::Value* Benchmark::EntryToVal(TypeTag type, TypeTag subtype)
 		// Then - common stuff
 		{
 		// how many entries do we have...
-		unsigned int length = rand() / (RAND_MAX / 15);
+		unsigned int length = random() / (RAND_MAX / 15);
 
 		Value** lvals = new Value* [length];
 

src/util.cc

@@ -633,12 +633,20 @@ static bool write_random_seeds(const char* write_file, uint32 seed,
 static bool bro_rand_determistic = false;
 static unsigned int bro_rand_state = 0;
 
-static void bro_srand(unsigned int seed, bool deterministic)
+static void bro_srandom(unsigned int seed, bool deterministic)
 	{
 	bro_rand_state = seed;
 	bro_rand_determistic = deterministic;
 
-	srand(seed);
+	srandom(seed);
+	}
+
+void bro_srandom(unsigned int seed)
+	{
+	if ( bro_rand_determistic )
+		bro_rand_state = seed;
+	else
+		srandom(seed);
 	}
 
 void init_random_seed(uint32 seed, const char* read_file, const char* write_file)
@@ -705,7 +713,7 @@ void init_random_seed(uint32 seed, const char* read_file, const char* write_file
 			seeds_done = true;
 		}
 
-	bro_srand(seed, seeds_done);
+	bro_srandom(seed, seeds_done);
 
 	if ( ! hmac_key_set )
 		{

src/util.h

@@ -159,6 +159,10 @@ extern bool have_random_seed();
 // predictable PRNG.
 long int bro_random();
 
+// Calls the system srandom() function with the given seed if not running
+// in deterministic mode, else it updates the state of the deterministic PRNG
+void bro_srandom(unsigned int seed);
+
 extern uint64 rand64bit();
 
 // Each event source that may generate events gets an internally unique ID.

testing/btest/Baseline/bifs.rand/out

@@ -1,6 +1,6 @@
-185
+985
-236
+474
-805
+738
-47
+4
-996
+634
-498
+473

testing/btest/Baseline/bifs.rand/out.2

@@ -0,0 +1,6 @@
+985
+474
+738
+974
+371
+638

testing/btest/bifs/rand.bro

@@ -1,6 +1,10 @@
 #
-# @TEST-EXEC: bro %INPUT >out
+# @TEST-EXEC: bro -b %INPUT >out
+# @TEST-EXEC: bro -b %INPUT do_seed=F >out.2
 # @TEST-EXEC: btest-diff out
+# @TEST-EXEC: btest-diff out.2
+
+const do_seed = T &redef;
 
 event bro_init()
 	{
@@ -12,7 +16,8 @@ event bro_init()
 	print b;
 	print c;
 
-	srand(575);
+	if ( do_seed )
+		srand(575);
 
 	local d = rand(1000);
 	local e = rand(1000);