Bug 1670041

Summary:	glibc: libresolv should use IP_RECVERR/IPV6_RECVERR to avoid long timeouts
Product:	Red Hat Enterprise Linux 7	Reporter:	Florian Weimer <fweimer>
Component:	glibc	Assignee:	Arjun Shankar <ashankar>
Status:	CLOSED ERRATA	QA Contact:	qe-baseos-tools-bugs
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.7	CC:	ashankar, bgollahe, codonell, dj, fweimer, mnewsome, pfrankli, skolosov
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	glibc-2.17-295.el7	Doc Type:	Bug Fix
Doc Text:	Cause: glibc did not enable the reporting of all ICMP errors when performing a DNS lookup. Consequence: When the network reported that a configured DNS server was unreachable during a DNS lookup, the resolver would not immediately recognize the failure and query the next configured DNS server. Instead it would wait for a timeout, leading to a lookup time that was longer than necessary. Fix: The resolver now enables reporting of all ICMP errors when performing a DNS lookup. Result: The resolver now recognizes an unreachable DNS server and tries the next one immediately upon receiving an ICMP error message, leading to a faster DNS lookup in such cases.	Story Points:	---
Clone Of:	1670028	Environment:
Last Closed:	2020-03-31 19:08:29 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1670028, 1670043
Bug Blocks:	1710258

Description Florian Weimer 2019-01-28 13:31:41 UTC

+++ This bug was initially created as a clone of Bug #1670028 +++

The Linux kernel does not forward certain ICMP errors to userspace unless IP_RECVERR/IPV6_RECVERR is specified.  We should use this socket option in the DNS stub resolver, as suggested in the upstream bug.

Comment 6 Sergey Kolosov 2019-10-24 07:48:05 UTC

Verified with strace

Comment 8 errata-xmlrpc 2020-03-31 19:08:29 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2020:0989