From patchwork Mon May 11 09:23:54 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Schwab X-Patchwork-Id: 6662 Received: (qmail 82478 invoked by alias); 11 May 2015 09:24:00 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 82450 invoked by uid 89); 11 May 2015 09:23:59 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.0 required=5.0 tests=AWL, BAYES_50, KAM_LAZY_DOMAIN_SECURITY, T_RP_MATCHES_RCVD autolearn=no version=3.3.2 X-HELO: mx2.suse.de From: Andreas Schwab To: libc-alpha@sourceware.org Subject: [PATCH] Simplify handling of nameserver configuration in resolver X-Yow: My FAVORITE group is "QUESTION MARK & THE MYSTERIANS"... Date: Mon, 11 May 2015 11:23:54 +0200 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Much of the IPv6 support in resolv.conf is overly convoluted and hard to understand, proven by the fact that trying to fix something in the past has always (re-)introduced bugs in other corners. This patch removes the use of the ext.nsmap member of struct __res_state and always uses an identity mapping betwen the nsaddr_list array and the ext.nsaddrs array. The fact that a nameserver has an IPv6 address is signalled by setting nsaddr_list[].sin_family to zero. This has been suceessfully tested for some time in openSUSE Factory. Andreas. [BZ #13028] [BZ #17053] * resolv/res_init.c (__res_vinit): Remove use of ext.nsmap member of struct __res_state. * resolv/res_send.c (__libc_res_nsend): Likewise. (get_nsaddr): New function. (res_ourserver_p, send_vc, reopen): Use it instead of accessing statp directly. --- resolv/res_init.c | 47 +++++----------- resolv/res_send.c | 164 +++++++++++++++++++++++------------------------------- 2 files changed, 84 insertions(+), 127 deletions(-) diff --git a/resolv/res_init.c b/resolv/res_init.c index 553ba12..66561ff 100644 --- a/resolv/res_init.c +++ b/resolv/res_init.c @@ -153,10 +153,8 @@ __res_vinit(res_state statp, int preinit) { char *cp, **pp; int n; char buf[BUFSIZ]; - int nserv = 0; /* number of IPv4 nameservers read from file */ -#ifdef _LIBC - int nservall = 0; /* number of (IPv4 + IPV6) nameservers read from file */ -#endif + int nserv = 0; /* number of nameservers read from file */ + int have_serv6 = 0; int haveenv = 0; int havesearch = 0; #ifdef RESOLVSORT @@ -184,15 +182,9 @@ __res_vinit(res_state statp, int preinit) { statp->_flags = 0; statp->qhook = NULL; statp->rhook = NULL; - statp->_u._ext.nsinit = 0; statp->_u._ext.nscount = 0; -#ifdef _LIBC - statp->_u._ext.nscount6 = 0; - for (n = 0; n < MAXNS; n++) { - statp->_u._ext.nsaddrs[n] = NULL; - statp->_u._ext.nsmap[n] = MAXNS; - } -#endif + for (n = 0; n < MAXNS; n++) + statp->_u._ext.nsaddrs[n] = NULL; /* Allow user to override the local domain definition */ if ((cp = getenv("LOCALDOMAIN")) != NULL) { @@ -296,11 +288,7 @@ __res_vinit(res_state statp, int preinit) { continue; } /* read nameservers to query */ -#ifdef _LIBC - if (MATCH(buf, "nameserver") && nservall < MAXNS) { -#else if (MATCH(buf, "nameserver") && nserv < MAXNS) { -#endif struct in_addr a; cp = buf + sizeof("nameserver") - 1; @@ -308,13 +296,12 @@ __res_vinit(res_state statp, int preinit) { cp++; if ((*cp != '\0') && (*cp != '\n') && __inet_aton(cp, &a)) { - statp->nsaddr_list[nservall].sin_addr = a; - statp->nsaddr_list[nservall].sin_family = AF_INET; - statp->nsaddr_list[nservall].sin_port = + statp->nsaddr_list[nserv].sin_addr = a; + statp->nsaddr_list[nserv].sin_family = AF_INET; + statp->nsaddr_list[nserv].sin_port = htons(NAMESERVER_PORT); nserv++; #ifdef _LIBC - nservall++; } else { struct in6_addr a6; char *el; @@ -356,10 +343,11 @@ __res_vinit(res_state statp, int preinit) { } } - statp->_u._ext.nsaddrs[nservall] = sa6; - statp->_u._ext.nssocks[nservall] = -1; - statp->_u._ext.nsmap[nservall] = MAXNS + 1; - nservall++; + statp->nsaddr_list[nserv].sin_family = 0; + statp->_u._ext.nsaddrs[nserv] = sa6; + statp->_u._ext.nssocks[nserv] = -1; + have_serv6 = 1; + nserv++; } } #endif @@ -414,10 +402,9 @@ __res_vinit(res_state statp, int preinit) { continue; } } - statp->nscount = nservall; + statp->nscount = nserv; #ifdef _LIBC - if (nservall - nserv > 0) { - statp->_u._ext.nscount6 = nservall - nserv; + if (have_serv6) { /* We try IPv6 servers again. */ statp->ipv6_unavail = false; } @@ -606,11 +593,7 @@ __res_iclose(res_state statp, bool free_addr) { statp->_vcsock = -1; statp->_flags &= ~(RES_F_VC | RES_F_CONN); } -#ifdef _LIBC - for (ns = 0; ns < MAXNS; ns++) -#else for (ns = 0; ns < statp->_u._ext.nscount; ns++) -#endif if (statp->_u._ext.nsaddrs[ns]) { if (statp->_u._ext.nssocks[ns] != -1) { close_not_cancel_no_status(statp->_u._ext.nssocks[ns]); @@ -621,8 +604,6 @@ __res_iclose(res_state statp, bool free_addr) { statp->_u._ext.nsaddrs[ns] = NULL; } } - if (free_addr) - statp->_u._ext.nsinit = 0; } libc_hidden_def (__res_iclose) diff --git a/resolv/res_send.c b/resolv/res_send.c index c35fb66..5e53cc2 100644 --- a/resolv/res_send.c +++ b/resolv/res_send.c @@ -184,6 +184,7 @@ evNowTime(struct timespec *res) { /* Forward. */ +static struct sockaddr *get_nsaddr (res_state, int); static int send_vc(res_state, const u_char *, int, const u_char *, int, u_char **, int *, int *, int, u_char **, @@ -221,20 +222,21 @@ res_ourserver_p(const res_state statp, const struct sockaddr_in6 *inp) in_port_t port = in4p->sin_port; in_addr_t addr = in4p->sin_addr.s_addr; - for (ns = 0; ns < MAXNS; ns++) { + for (ns = 0; ns < statp->nscount; ns++) { const struct sockaddr_in *srv = - (struct sockaddr_in *)EXT(statp).nsaddrs[ns]; + (struct sockaddr_in *) get_nsaddr (statp, ns); - if ((srv != NULL) && (srv->sin_family == AF_INET) && + if ((srv->sin_family == AF_INET) && (srv->sin_port == port) && (srv->sin_addr.s_addr == INADDR_ANY || srv->sin_addr.s_addr == addr)) return (1); } } else if (inp->sin6_family == AF_INET6) { - for (ns = 0; ns < MAXNS; ns++) { - const struct sockaddr_in6 *srv = EXT(statp).nsaddrs[ns]; - if ((srv != NULL) && (srv->sin6_family == AF_INET6) && + for (ns = 0; ns < statp->nscount; ns++) { + const struct sockaddr_in6 *srv + = (struct sockaddr_in6 *) get_nsaddr (statp, ns); + if ((srv->sin6_family == AF_INET6) && (srv->sin6_port == inp->sin6_port) && !(memcmp(&srv->sin6_addr, &in6addr_any, sizeof (struct in6_addr)) && @@ -384,80 +386,48 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen, * If the ns_addr_list in the resolver context has changed, then * invalidate our cached copy and the associated timing data. */ - if (EXT(statp).nsinit) { + if (EXT(statp).nscount != 0) { int needclose = 0; if (EXT(statp).nscount != statp->nscount) needclose++; else - for (ns = 0; ns < MAXNS; ns++) { - unsigned int map = EXT(statp).nsmap[ns]; - if (map < MAXNS + for (ns = 0; ns < statp->nscount; ns++) { + if (statp->nsaddr_list[ns].sin_family != 0 && !sock_eq((struct sockaddr_in6 *) - &statp->nsaddr_list[map], + &statp->nsaddr_list[ns], EXT(statp).nsaddrs[ns])) { needclose++; break; } } - if (needclose) + if (needclose) { __res_iclose(statp, false); + EXT(statp).nscount = 0; + } } /* * Maybe initialize our private copy of the ns_addr_list. */ - if (EXT(statp).nsinit == 0) { - unsigned char map[MAXNS]; - - memset (map, MAXNS, sizeof (map)); - for (n = 0; n < MAXNS; n++) { - ns = EXT(statp).nsmap[n]; - if (ns < statp->nscount) - map[ns] = n; - else if (ns < MAXNS) { - free(EXT(statp).nsaddrs[n]); - EXT(statp).nsaddrs[n] = NULL; - EXT(statp).nsmap[n] = MAXNS; - } - } - n = statp->nscount; - if (statp->nscount > EXT(statp).nscount) - for (n = EXT(statp).nscount, ns = 0; - n < statp->nscount; n++) { - while (ns < MAXNS - && EXT(statp).nsmap[ns] != MAXNS) - ns++; - if (ns == MAXNS) - break; - /* NS never exceeds MAXNS, but gcc 4.9 somehow - does not see this. */ - DIAG_PUSH_NEEDS_COMMENT; - DIAG_IGNORE_NEEDS_COMMENT (4.9, - "-Warray-bounds"); - EXT(statp).nsmap[ns] = n; - DIAG_POP_NEEDS_COMMENT; - map[n] = ns++; - } - EXT(statp).nscount = n; - for (ns = 0; ns < EXT(statp).nscount; ns++) { - n = map[ns]; - if (EXT(statp).nsaddrs[n] == NULL) - EXT(statp).nsaddrs[n] = + if (EXT(statp).nscount == 0) { + for (ns = 0; ns < statp->nscount; ns++) { + EXT(statp).nssocks[ns] = -1; + if (statp->nsaddr_list[ns].sin_family == 0) + continue; + if (EXT(statp).nsaddrs[ns] == NULL) + EXT(statp).nsaddrs[ns] = malloc(sizeof (struct sockaddr_in6)); - if (EXT(statp).nsaddrs[n] != NULL) { - memset (mempcpy(EXT(statp).nsaddrs[n], + if (EXT(statp).nsaddrs[ns] != NULL) + memset (mempcpy(EXT(statp).nsaddrs[ns], &statp->nsaddr_list[ns], sizeof (struct sockaddr_in)), '\0', sizeof (struct sockaddr_in6) - sizeof (struct sockaddr_in)); - EXT(statp).nssocks[n] = -1; - n++; - } } - EXT(statp).nsinit = 1; + EXT(statp).nscount = statp->nscount; } /* @@ -466,44 +436,37 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen, */ if (__builtin_expect ((statp->options & RES_ROTATE) != 0, 0) && (statp->options & RES_BLAST) == 0) { - struct sockaddr_in6 *ina; - unsigned int map; - - n = 0; - while (n < MAXNS && EXT(statp).nsmap[n] == MAXNS) - n++; - if (n < MAXNS) { - ina = EXT(statp).nsaddrs[n]; - map = EXT(statp).nsmap[n]; - for (;;) { - ns = n + 1; - while (ns < MAXNS - && EXT(statp).nsmap[ns] == MAXNS) - ns++; - if (ns == MAXNS) - break; - EXT(statp).nsaddrs[n] = EXT(statp).nsaddrs[ns]; - EXT(statp).nsmap[n] = EXT(statp).nsmap[ns]; - n = ns; - } - EXT(statp).nsaddrs[n] = ina; - EXT(statp).nsmap[n] = map; + struct sockaddr_in ina; + struct sockaddr_in6 *inp; + int lastns = statp->nscount - 1; + int fd; + + inp = EXT(statp).nsaddrs[0]; + ina = statp->nsaddr_list[0]; + fd = EXT(statp).nssocks[0]; + for (ns = 0; ns < lastns; ns++) { + EXT(statp).nsaddrs[ns] = EXT(statp).nsaddrs[ns + 1]; + statp->nsaddr_list[ns] = statp->nsaddr_list[ns + 1]; + EXT(statp).nssocks[ns] = EXT(statp).nssocks[ns + 1]; } + EXT(statp).nsaddrs[lastns] = inp; + statp->nsaddr_list[lastns] = ina; + EXT(statp).nssocks[lastns] = fd; } /* * Send request, RETRY times, or until successful. */ for (try = 0; try < statp->retry; try++) { - for (ns = 0; ns < MAXNS; ns++) + for (ns = 0; ns < statp->nscount; ns++) { #ifdef DEBUG char tmpbuf[40]; #endif - struct sockaddr_in6 *nsap = EXT(statp).nsaddrs[ns]; +#if defined USE_HOOKS || defined DEBUG + struct sockaddr *nsap = get_nsaddr (statp, ns); +#endif - if (nsap == NULL) - goto next_ns; same_ns: #ifdef USE_HOOKS if (__glibc_unlikely (statp->qhook != NULL)) { @@ -542,9 +505,9 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen, Dprint(statp->options & RES_DEBUG, (stdout, ";; Querying server (# %d) address = %s\n", - ns + 1, inet_ntop(nsap->sin6_family, - (nsap->sin6_family == AF_INET6 - ? &nsap->sin6_addr + ns + 1, inet_ntop(nsap->sa_family, + (nsap->sa_family == AF_INET6 + ? &((struct sockaddr_in6 *) nsap)->sin6_addr : &((struct sockaddr_in *) nsap)->sin_addr), tmpbuf, sizeof (tmpbuf)))); @@ -660,6 +623,21 @@ libresolv_hidden_def (res_nsend) /* Private */ +static struct sockaddr * +get_nsaddr (res_state statp, int n) +{ + + if (statp->nsaddr_list[n].sin_family == 0 && EXT(statp).nsaddrs[n] != NULL) + /* EXT(statp).nsaddrs[n] holds an address that is larger than + struct sockaddr, and user code did not update + statp->nsaddr_list[n]. */ + return (struct sockaddr *) EXT(statp).nsaddrs[n]; + else + /* User code updated statp->nsaddr_list[n], or statp->nsaddr_list[n] + has the same content as EXT(statp).nsaddrs[n]. */ + return (struct sockaddr *) (void *) &statp->nsaddr_list[n]; +} + static int send_vc(res_state statp, const u_char *buf, int buflen, const u_char *buf2, int buflen2, @@ -674,7 +652,7 @@ send_vc(res_state statp, // XXX REMOVE // int anssiz = *anssizp; HEADER *anhp = (HEADER *) ans; - struct sockaddr_in6 *nsap = EXT(statp).nsaddrs[ns]; + struct sockaddr *nsap = get_nsaddr (statp, ns); int truncating, connreset, n; /* On some architectures compiler might emit a warning indicating 'resplen' may be used uninitialized. However if buf2 == NULL @@ -711,8 +689,8 @@ send_vc(res_state statp, if (getpeername(statp->_vcsock, (struct sockaddr *)&peer, &size) < 0 || - !sock_eq(&peer, nsap)) { - __res_iclose(statp, false); + !sock_eq(&peer, (struct sockaddr_in6 *) nsap)) { + __res_iclose(statp, false); statp->_flags &= ~RES_F_VC; } } @@ -721,20 +699,19 @@ send_vc(res_state statp, if (statp->_vcsock >= 0) __res_iclose(statp, false); - statp->_vcsock = socket(nsap->sin6_family, SOCK_STREAM, 0); + statp->_vcsock = socket(nsap->sa_family, SOCK_STREAM, 0); if (statp->_vcsock < 0) { *terrno = errno; Perror(statp, stderr, "socket(vc)", errno); return (-1); } __set_errno (0); - if (connect(statp->_vcsock, (struct sockaddr *)nsap, - nsap->sin6_family == AF_INET + if (connect(statp->_vcsock, nsap, + nsap->sa_family == AF_INET ? sizeof (struct sockaddr_in) : sizeof (struct sockaddr_in6)) < 0) { *terrno = errno; - Aerror(statp, stderr, "connect/vc", errno, - (struct sockaddr *) nsap); + Aerror(statp, stderr, "connect/vc", errno, nsap); __res_iclose(statp, false); return (0); } @@ -945,8 +922,7 @@ static int reopen (res_state statp, int *terrno, int ns) { if (EXT(statp).nssocks[ns] == -1) { - struct sockaddr *nsap - = (struct sockaddr *) EXT(statp).nsaddrs[ns]; + struct sockaddr *nsap = get_nsaddr (statp, ns); socklen_t slen; /* only try IPv6 if IPv6 NS and if not failed before */