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From: "A. Wilcox" <>
Cc: "A. Wilcox" <>
Subject: [musl] [PATCH] dns: Prefer monotonic clock for DNS lookup timeouts
Date: Thu, 29 Dec 2022 21:21:32 -0600	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

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

Now we try CLOCK_MONOTONIC and only fall back to CLOCK_REALTIME when it
is unavailable.
 src/network/res_msend.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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;
2.37.1 (Apple Git-137.1)

      reply	other threads:[~2022-12-30  3:22 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-01 11:24 [musl] " Gregor Jasny
2022-12-01 15:11 ` Rich Felker
2022-12-30  3:20   ` A. Wilcox
2022-12-30  3:21     ` A. Wilcox [this message]

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