From 1b4e84c56df0f8ca30f6bc05962a860f869e71df Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Tue, 19 May 2020 19:25:42 -0400
Subject: fix return value of res_send, res_query on errors from nameserver
the internal __res_msend returns 0 on timeout without having obtained
any conclusive answer, but in this case has not filled in meaningful
anslen. res_send wrongly treated that as success, but returned a zero
answer length. any reasonable caller would eventually end up treating
that as an error when attempting to parse/validate it, but it should
just be reported as an error.
alternatively we could return the last-received inconclusive answer
(typically servfail), but doing so would require internal changes in
__res_msend. this may be considered later.
---
src/network/res_send.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
(limited to 'src/network')
diff --git a/src/network/res_send.c b/src/network/res_send.c
index b9cea0bf..ee4abf1f 100644
--- a/src/network/res_send.c
+++ b/src/network/res_send.c
@@ -3,7 +3,7 @@
int __res_send(const unsigned char *msg, int msglen, unsigned char *answer, int anslen)
{
int r = __res_msend(1, &msg, &msglen, &answer, &anslen, anslen);
- return r<0 ? r : anslen;
+ return r<0 || !anslen ? -1 : anslen;
}
weak_alias(__res_send, res_send);
--
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