Merge pull request #2544 from signalwire/SWITCH_RAND_MAX

[Core] Introduce SWITCH_RAND_MAX to switch_rand()
signalwire · Jul 29, 2024 · be3c0b3 · be3c0b3
2 parents 56981d1 + a99ed5c
commit be3c0b3
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Showing 2 changed files with 11 additions and 4 deletions.
diff --git a/src/include/switch_types.h b/src/include/switch_types.h
@@ -599,6 +599,13 @@ SWITCH_DECLARE_DATA extern switch_filenames SWITCH_GLOBAL_filenames;
 
 #define SWITCH_ACCEPTABLE_INTERVAL(_i) (_i && _i <= SWITCH_MAX_INTERVAL && (_i % 10) == 0)
 
+/* Check if RAND_MAX is a power of 2 minus 1 or in other words all bits set */
+#if ((RAND_MAX) & ((RAND_MAX) + 1)) == 0 && (RAND_MAX) != 0
+#define SWITCH_RAND_MAX RAND_MAX
+#else
+#define SWITCH_RAND_MAX 0x7fff
+#endif
+
 typedef enum {
 	SWITCH_RW_READ,
 	SWITCH_RW_WRITE

diff --git a/src/switch_utils.c b/src/switch_utils.c
@@ -4835,8 +4835,8 @@ SWITCH_DECLARE(int) switch_rand(void)
 
 	BCryptCloseAlgorithmProvider(hAlgorithm, 0);
 
-	/* Make sure we return from 0 to RAND_MAX */
-	return (random_number & 0x7FFF);
+	/* Make sure we return from 0 to SWITCH_RAND_MAX */
+	return (random_number & (SWITCH_RAND_MAX));
 #elif defined(__unix__) || defined(__APPLE__)
 	int random_fd = open("/dev/urandom", O_RDONLY);
 	ssize_t result;
@@ -4865,8 +4865,8 @@ SWITCH_DECLARE(int) switch_rand(void)
 
 	close(random_fd);
 
-	/* Make sure we return from 0 to RAND_MAX */
-	return (random_number & 0x7FFF);
+	/* Make sure we return from 0 to SWITCH_RAND_MAX */
+	return (random_number & (SWITCH_RAND_MAX));
 #else
 	return rand();
 #endif