From: A. Wilcox <AWilcox@Wilcox-Tech.com>
Date: Fri, 30 Dec 2022 03:21:32 +0000 (-0600)
Subject: dns: prefer monotonic clock for timeouts
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=7d756e1c04de6eb3f2b3d3e1141a218bb329fcfb;p=musl

dns: prefer monotonic clock for timeouts

Before this commit, DNS timeouts always used CLOCK_REALTIME, which
could produce spurious timeouts or delays if wall time changed for
whatever reason.

Now we try CLOCK_MONOTONIC and only fall back to CLOCK_REALTIME when
it is unavailable.
---

diff --git a/src/network/res_msend.c b/src/network/res_msend.c
index 11c6aa0e..fef7e3a2 100644
--- a/src/network/res_msend.c
+++ b/src/network/res_msend.c
@@ -25,7 +25,8 @@ static void cleanup(void *p)
 static unsigned long mtime()
 {
 	struct timespec ts;
-	clock_gettime(CLOCK_REALTIME, &ts);
+	if (clock_gettime(CLOCK_MONOTONIC, &ts) < 0 && errno == ENOSYS)
+		clock_gettime(CLOCK_REALTIME, &ts);
 	return (unsigned long)ts.tv_sec * 1000
 		+ ts.tv_nsec / 1000000;
 }