From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7145 invoked by alias); 30 Jun 2012 03:16:22 -0000 Received: (qmail 7137 invoked by uid 22791); 30 Jun 2012 03:16:21 -0000 X-SWARE-Spam-Status: No, hits=-3.7 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,KHOP_THREADED,TW_JV X-Spam-Check-By: sourceware.org Received: from localhost (HELO sourceware.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sat, 30 Jun 2012 03:16:08 +0000 From: "jvb127 at gmail dot com" To: glibc-bugs@sources.redhat.com Subject: [Bug network/14307] getaddrinfo() sends superfluous DNS requests in x86_64 programs for certain hostnames Date: Sat, 30 Jun 2012 03:16:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: glibc X-Bugzilla-Component: network X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: jvb127 at gmail dot com X-Bugzilla-Status: NEW X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: siddhesh at redhat dot com X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org X-SW-Source: 2012-06/txt/msg00347.txt.bz2 http://sourceware.org/bugzilla/show_bug.cgi?id=14307 --- Comment #4 from Jeroen van Bemmel 2012-06-30 03:16:07 UTC --- in function getanswer_r (resolv/nss_dns/dns-host.c) the temporary buffer is used for the following struct: struct host_data { char *aliases[MAX_NR_ALIASES]; unsigned char host_addr[16]; /* IPv4 or IPv6 */ char *h_addr_ptrs[0]; } *host_data sizeof( struct host_data ) == 400 for x86_64, and 208 for x86 32-bit. One could argue that the code works as designed, but I believe it is desirable if glibc exhibits the same externally observable behaviour for both x86 and x86_64 versions. 512 - 400 leaves little room for common DNS query responses like "www.google.com". One could simply allocate a larger temporary buffer for x86_64 ( e.g. 512 * sizeof(void*) / 4 ), but perhaps a better fix is to not use the temporary buffer for the host_data struct at all (and e.g. use alloca instead, or simply place it on the stack - although the code does explicitly align it in case the buffer is unaligned, which it isn't btw) -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.