Date: Thu, 23 Feb 2006 02:08:17 +0900 From: Hajimu UMEMOTO <ume@freebsd.org> To: Rostislav Krasny <rosti.bsd@gmail.com> Cc: freebsd-stable@freebsd.org, freebsd-stable-local@be-well.ilk.org, Yar Tikhiy <yar@comp.chem.msu.su>, dwmalone@maths.tcd.ie, des@des.no, mak@ll.mit.edu, MH@kernel32.de Subject: Re: SSH login takes very long time...sometimes Message-ID: <yge1wxvz5ha.wl%ume@mahoroba.org> In-Reply-To: <20060222024430.ad4b5c60.rosti.bsd@gmail.com> References: <59e2ee810512250841t75157e62rec9dc389ac716534@mail.gmail.com> <20051227101621.GA16276@walton.maths.tcd.ie> <86irrfoix5.fsf@xps.des.no> <20060218012029.e146e2ff.rosti.bsd@gmail.com> <20060219104912.GB20500@comp.chem.msu.su> <20060219225701.0e3e244b.rosti.bsd@gmail.com> <20060221165959.GB77513@comp.chem.msu.su> <20060222024430.ad4b5c60.rosti.bsd@gmail.com>
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Hi, >>>>> On Wed, 22 Feb 2006 02:44:30 +0200 >>>>> Rostislav Krasny <rosti.bsd@gmail.com> said: rosti> On Tue, 21 Feb 2006 19:59:59 +0300 rosti> Yar Tikhiy <yar@comp.chem.msu.su> wrote: rosti> I forgot that a "search" resolver(5) parameter is useless for reverse rosti> resolving. But that "doubling" of name->IP requests with an empty (or rosti> root, according to resolver(5)) domain in the "search" is still a bug, rosti> IMHO. Although it shouldn't affect the sshd. I looked BIND9's resolver, and took the related part into our resolver. However, it seems to me that there is still same issue in BIND9's resolver. So, I change more bit. Please try the following patch and let me know the result: Index: lib/libc/net/getaddrinfo.c diff -u -p lib/libc/net/getaddrinfo.c.orig lib/libc/net/getaddrinfo.c --- lib/libc/net/getaddrinfo.c.orig Sat Jul 23 03:21:28 2005 +++ lib/libc/net/getaddrinfo.c Thu Feb 23 01:43:49 2006 @@ -2405,7 +2405,9 @@ res_searchN(name, target) HEADER *hp = (HEADER *)(void *)target->answer; /*XXX*/ u_int dots; int trailing_dot, ret, saved_herrno; - int got_nodata = 0, got_servfail = 0, tried_as_is = 0; + int got_nodata = 0, got_servfail = 0, root_on_list = 0; + int tried_as_is = 0; + int searched = 0; char abuf[MAXDNAME]; if ((_res.options & RES_INIT) == 0 && res_init() == -1) { @@ -2429,13 +2431,14 @@ res_searchN(name, target) return (res_queryN(cp, target)); /* - * If there are dots in the name already, let's just give it a try - * 'as is'. The threshold can be set with the "ndots" option. + * If there are enough dots in the name, let's just give it a + * try 'as is'. The threshold can be set with the "ndots" option. + * Also, query 'as is', if there is a trailing dot in the name. */ saved_herrno = -1; - if (dots >= _res.ndots) { + if (dots >= _res.ndots || trailing_dot) { ret = res_querydomainN(name, NULL, target); - if (ret > 0) + if (ret > 0 || trailing_dot) return (ret); saved_herrno = h_errno; tried_as_is++; @@ -2454,6 +2457,14 @@ res_searchN(name, target) for (domain = (const char * const *)_res.dnsrch; *domain && !done; domain++) { + searched = 1; + + if (domain[0][0] == '\0' || + (domain[0][0] == '.' && domain[0][1] == '\0')) + root_on_list++; + + if (root_on_list && tried_as_is) + continue; ret = res_querydomainN(name, *domain, target); if (ret > 0) @@ -2505,11 +2516,11 @@ res_searchN(name, target) } /* - * if we have not already tried the name "as is", do that now. - * note that we do this regardless of how many dots were in the - * name or whether it ends with a dot. + * If the query has not already been tried as is then try it + * unless RES_NOTLDQUERY is set and there were no dots. */ - if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) { + if ((dots || !searched || !(_res.options & RES_NOTLDQUERY)) && + !(tried_as_is || root_on_list)) { ret = res_querydomainN(name, NULL, target); if (ret > 0) return (ret); Index: lib/libc/net/res_query.c diff -u -p lib/libc/net/res_query.c.orig lib/libc/net/res_query.c --- lib/libc/net/res_query.c.orig Fri Apr 15 23:42:29 2005 +++ lib/libc/net/res_query.c Thu Feb 23 01:43:49 2006 @@ -198,7 +198,9 @@ res_search(name, class, type, answer, an char tmp[MAXDNAME]; u_int dots; int trailing_dot, ret, saved_herrno; - int got_nodata = 0, got_servfail = 0, tried_as_is = 0; + int got_nodata = 0, got_servfail = 0, root_on_list = 0; + int tried_as_is = 0; + int searched = 0; if ((_res.options & RES_INIT) == 0 && res_init() == -1) { h_errno = NETDB_INTERNAL; @@ -218,13 +220,14 @@ res_search(name, class, type, answer, an return (res_query(cp, class, type, answer, anslen)); /* - * If there are dots in the name already, let's just give it a try - * 'as is'. The threshold can be set with the "ndots" option. + * If there are enough dots in the name, let's just give it a + * try 'as is'. The threshold can be set with the "ndots" option. + * Also, query 'as is', if there is a trailing dot in the name. */ saved_herrno = -1; - if (dots >= _res.ndots) { + if (dots >= _res.ndots || trailing_dot) { ret = res_querydomain(name, NULL, class, type, answer, anslen); - if (ret > 0) + if (ret > 0 || trailing_dot) return (ret); saved_herrno = h_errno; tried_as_is++; @@ -243,6 +246,14 @@ res_search(name, class, type, answer, an for (domain = (const char * const *)_res.dnsrch; *domain && !done; domain++) { + searched = 1; + + if (domain[0][0] == '\0' || + (domain[0][0] == '.' && domain[0][1] == '\0')) + root_on_list++; + + if (root_on_list && tried_as_is) + continue; ret = res_querydomain(name, *domain, class, type, answer, anslen); @@ -308,11 +319,11 @@ res_search(name, class, type, answer, an } /* - * If we have not already tried the name "as is", do that now. - * note that we do this regardless of how many dots were in the - * name or whether it ends with a dot unless NOTLDQUERY is set. + * If the query has not already been tried as is then try it + * unless RES_NOTLDQUERY is set and there were no dots. */ - if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) { + if ((dots || !searched || !(_res.options & RES_NOTLDQUERY)) && + !(tried_as_is || root_on_list)) { ret = res_querydomain(name, NULL, class, type, answer, anslen); if (ret > 0) return (ret); Sincerely, -- Hajimu UMEMOTO @ Internet Mutual Aid Society Yokohama, Japan ume@mahoroba.org ume@{,jp.}FreeBSD.org http://www.imasy.org/~ume/
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