From 424a5b489d071f1e96c0a663fa674bf16dcd08f4 Mon Sep 17 00:00:00 2001
From: Clemens Famulla-Conrad <cfamullaconrad@suse.de>
Date: Thu, 15 Jun 2023 10:39:26 +0200
Subject: [PATCH] timer: add ni_timeout_random() function

---
 include/wicked/time.h |  2 ++
 src/timer.c           | 31 +++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/include/wicked/time.h b/include/wicked/time.h
index 166f517ac..3adff6e45 100644
--- a/include/wicked/time.h
+++ b/include/wicked/time.h
@@ -100,4 +100,6 @@ extern ni_timeout_t		ni_timeout_left(const struct timeval *, const struct timeva
 
 extern ni_bool_t		ni_timeval_add_timeout(struct timeval *, ni_timeout_t);
 
+extern ni_timeout_t		ni_timeout_random_range(ni_timeout_t min, ni_timeout_t max);
+
 #endif /* WICKED_TIME_H */
diff --git a/src/timer.c b/src/timer.c
index b37b455e9..ab67c7863 100644
--- a/src/timer.c
+++ b/src/timer.c
@@ -430,6 +430,37 @@ ni_timeout_randomize(ni_timeout_t timeout, const ni_int_range_t *jitter)
 	return rtimeout;
 }
 
+ni_timeout_t
+ni_timeout_random_range(ni_timeout_t min, ni_timeout_t max)
+{
+	ni_timeout_t randval = 0;
+	ni_timeout_t range;
+
+	if (max <= min)
+		return min;
+
+	if (min >= NI_TIMEOUT_INFINITE || max >= NI_TIMEOUT_INFINITE)
+		return NI_TIMEOUT_INFINITE;
+
+	range = max - min + 1;
+
+	if (range > RAND_MAX) {
+		/*
+		 * Assume the largest number RAND_MAX is INT_MAX,
+		 * even random returns long int (64 or 32bit)...
+		 */
+		size_t count = sizeof(ni_timeout_t) / sizeof(int);
+		size_t i, bits = (sizeof(int) * 8) - 1;
+
+		for (i = 0; i < count; i++)
+			randval |= (ni_timeout_t)random() << (i * bits);
+	} else {
+		randval = (ni_timeout_t)random();
+	}
+
+	return min + (randval % range);
+}
+
 static ni_timeout_t
 ni_timeout_arm_randomized(struct timeval *deadline, ni_timeout_t timeout, const ni_int_range_t *jitter)
 {