#if !defined(lint) && !defined(SABER) static const char rcsid[] = "$Id: res_findzonecut.c,v 1.14.2.3 2003/01/14 23:15:06 dhankins Exp $"; #endif /* not lint */ /* * Copyright (c) 1999-2003 by Internet Software Consortium. * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS * SOFTWARE. */ /* Import. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include "minires/minires.h" #include "arpa/nameser.h" /* Data structures. */ typedef struct rr_a { ISC_LINK(struct rr_a) link; struct in_addr addr; } rr_a; typedef ISC_LIST(rr_a) rrset_a; typedef struct rr_ns { ISC_LINK(struct rr_ns) link; char *name; rrset_a addrs; } rr_ns; typedef ISC_LIST(rr_ns) rrset_ns; /* Forward. */ static int satisfy(res_state, const char *, rrset_ns *, struct in_addr *, int); static int add_addrs(res_state, rr_ns *, struct in_addr *, int); static ns_rcode get_soa(res_state, const char *, ns_class, char *, size_t, char *, size_t, rrset_ns *); static isc_result_t get_ns(res_state, const char *, ns_class, rrset_ns *); static isc_result_t get_glue(res_state, ns_class, rrset_ns *); static isc_result_t save_ns(res_state, ns_msg *, ns_sect, const char *, ns_class, rrset_ns *); static isc_result_t save_a(res_state, ns_msg *, ns_sect, const char *, ns_class, rrset_a *); static void free_nsrrset(rrset_ns *); static void free_nsrr(rrset_ns *, rr_ns *); static rr_ns * find_ns(rrset_ns *, const char *); static isc_result_t do_query(res_state, const char *, ns_class, ns_type, double *, ns_msg *, int *); /* Public. */ /* * int * res_findzonecut(res, dname, class, zname, zsize, addrs, naddrs) * find enclosing zone for a , and some server addresses * parameters: * res - resolver context to work within (is modified) * dname - domain name whose enclosing zone is desired * class - class of dname (and its enclosing zone) * zname - found zone name * zsize - allocated size of zname * addrs - found server addresses * naddrs - max number of addrs * return values: * < 0 - an error occurred (check errno) * = 0 - zname is now valid, but addrs[] wasn't changed * > 0 - zname is now valid, and return value is number of addrs[] found * notes: * this function calls res_nsend() which means it depends on correctly * functioning recursive nameservers (usually defined in /etc/resolv.conf * or its local equivilent). * * we start by asking for an SOA. if we get one as an * answer, that just means is a zone top, which is fine. * more than likely we'll be told to go pound sand, in the form of a * negative answer. * * note that we are not prepared to deal with referrals since that would * only come from authority servers and our correctly functioning local * recursive server would have followed the referral and got us something * more definite. * * if the authority section contains an SOA, this SOA should also be the * closest enclosing zone, since any intermediary zone cuts would've been * returned as referrals and dealt with by our correctly functioning local * recursive name server. but an SOA in the authority section should NOT * match our dname (since that would have been returned in the answer * section). an authority section SOA has to be "above" our dname. * * we cannot fail to find an SOA in this way. ultimately we'll return * a zname indicating the root zone if that's the closest enclosing zone. * however, since authority section SOA's were once optional, it's * possible that we'll have to go hunting for the enclosing SOA by * ripping labels off the front of our dname -- this is known as "doing * it the hard way." * * ultimately we want some server addresses, which are ideally the ones * pertaining to the SOA.MNAME, but only if there is a matching NS RR. * so the second phase (after we find an SOA) is to go looking for the * NS RRset for that SOA's zone. * * no answer section processed by this code is allowed to contain CNAME * or DNAME RR's. for the SOA query this means we strip a label and * keep going. for the NS and A queries this means we just give up. */ isc_result_t res_findzonecut(res_state statp, const char *dname, ns_class class, int opts, char *zname, size_t zsize, struct in_addr *addrs, int naddrs, int *count, void *zcookie) { char mname[NS_MAXDNAME]; u_long save_pfcode; rrset_ns nsrrs; int n = 0; isc_result_t rcode; DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d", dname, p_class(class), (long)zsize, naddrs)); save_pfcode = statp->pfcode; statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX | RES_PRF_QUES | RES_PRF_ANS | RES_PRF_AUTH | RES_PRF_ADD; ISC_LIST_INIT(nsrrs); DPRINTF (("look for a predefined zone statement")); rcode = find_cached_zone (dname, class, zname, zsize, addrs, naddrs, &n, zcookie); if (rcode == ISC_R_SUCCESS) goto done; DPRINTF(("get the soa, and see if it has enough glue")); if ((rcode = get_soa(statp, dname, class, zname, zsize, mname, sizeof mname, &nsrrs)) != ISC_R_SUCCESS || ((opts & RES_EXHAUSTIVE) == 0 && (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0)) goto done; DPRINTF(("get the ns rrset and see if it has enough glue")); if ((rcode = get_ns(statp, zname, class, &nsrrs)) != ISC_R_SUCCESS || ((opts & RES_EXHAUSTIVE) == 0 && (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0)) goto done; DPRINTF(("get the missing glue and see if it's finally enough")); if ((rcode = get_glue(statp, class, &nsrrs)) == ISC_R_SUCCESS) n = satisfy(statp, mname, &nsrrs, addrs, naddrs); /* If we found the zone, cache it. */ if (n > 0) cache_found_zone (class, zname, addrs, n); done: DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK")); free_nsrrset(&nsrrs); statp->pfcode = save_pfcode; if (count) *count = n; return rcode; } /* Private. */ static int satisfy(res_state statp, const char *mname, rrset_ns *nsrrsp, struct in_addr *addrs, int naddrs) { rr_ns *nsrr; int n, x; n = 0; nsrr = find_ns(nsrrsp, mname); if (nsrr != NULL) { x = add_addrs(statp, nsrr, addrs, naddrs); addrs += x; naddrs -= x; n += x; } for (nsrr = ISC_LIST_HEAD(*nsrrsp); nsrr != NULL && naddrs > 0; nsrr = ISC_LIST_NEXT(nsrr, link)) if (ns_samename(nsrr->name, mname) != 1) { x = add_addrs(statp, nsrr, addrs, naddrs); addrs += x; naddrs -= x; n += x; } DPRINTF(("satisfy(%s): %d", mname, n)); return (n); } static int add_addrs(res_state statp, rr_ns *nsrr, struct in_addr *addrs, int naddrs) { rr_a *arr; int n = 0; for (arr = ISC_LIST_HEAD(nsrr->addrs); arr != NULL; arr = ISC_LIST_NEXT(arr, link)) { if (naddrs <= 0) return (0); *addrs++ = arr->addr; naddrs--; n++; } DPRINTF(("add_addrs: %d", n)); return (n); } static ns_rcode get_soa(res_state statp, const char *dname, ns_class class, char *zname, size_t zsize, char *mname, size_t msize, rrset_ns *nsrrsp) { char tname[NS_MAXDNAME]; double resp[NS_PACKETSZ / sizeof (double)]; int n, i, ancount, nscount; ns_sect sect; ns_msg msg; u_int rcode; isc_result_t status; /* * Find closest enclosing SOA, even if it's for the root zone. */ /* First canonicalize dname (exactly one unescaped trailing "."). */ status = ns_makecanon(dname, tname, sizeof tname); if (status != ISC_R_SUCCESS) return status; dname = tname; /* Now grovel the subdomains, hunting for an SOA answer or auth. */ for (;;) { /* Leading or inter-label '.' are skipped here. */ while (*dname == '.') dname++; /* Is there an SOA? */ rcode = do_query(statp, dname, class, ns_t_soa, resp, &msg, &n); if (rcode != ISC_R_SUCCESS) { DPRINTF(("get_soa: do_query('%s', %s) failed (%d)", dname, p_class(class), n)); return rcode; } if (n > 0) { DPRINTF(("get_soa: CNAME or DNAME found")); sect = ns_s_max, n = 0; } else { ancount = ns_msg_count(msg, ns_s_an); nscount = ns_msg_count(msg, ns_s_ns); if (ancount > 0 && rcode == ISC_R_SUCCESS) sect = ns_s_an, n = ancount; else if (nscount > 0) sect = ns_s_ns, n = nscount; else sect = ns_s_max, n = 0; } for (i = 0; i < n; i++) { const char *t; const u_char *rdata; int rdlen; ns_rr rr; rcode = ns_parserr(&msg, sect, i, &rr) < 0; if (rcode != ISC_R_SUCCESS) { DPRINTF(("get_soa: ns_parserr(%s, %d) failed", p_section(sect, ns_o_query), i)); return rcode; } if (ns_rr_type(rr) == ns_t_cname || ns_rr_type(rr) == ns_t_dname) break; if (ns_rr_type(rr) != ns_t_soa || ns_rr_class(rr) != class) continue; t = ns_rr_name(rr); switch (sect) { case ns_s_an: if (ns_samedomain(dname, t) == 0) { DPRINTF(("get_soa: %s'%s', '%s') == 0", "ns_samedomain(", dname, t)); return ISC_R_NOTZONE; } break; case ns_s_ns: if (ns_samename(dname, t) == 1 || ns_samedomain(dname, t) == 0) { DPRINTF(("get_soa: %smain('%s', '%s')", "ns_samename() || !ns_samedo", dname, t)); return ISC_R_NOTZONE; } break; default: abort(); } if (strlen(t) + 1 > zsize) { DPRINTF(("get_soa: zname(%d) too small (%d)", zsize, strlen(t) + 1)); return ISC_R_NOSPACE; } strcpy(zname, t); rdata = ns_rr_rdata(rr); rdlen = ns_rr_rdlen(rr); if (ns_name_uncompress((u_char *)resp, ns_msg_end(msg), rdata, mname, msize) < 0) { DPRINTF(("get_soa: %s failed", "ns_name_uncompress")); return ISC_R_NOMEMORY; } rcode = save_ns(statp, &msg, ns_s_ns, zname, class, nsrrsp); if (rcode != ISC_R_SUCCESS) { DPRINTF(("get_soa: save_ns failed")); return rcode; } return ISC_R_SUCCESS; } /* If we're out of labels, then not even "." has an SOA! */ if (*dname == '\0') break; /* Find label-terminating "."; top of loop will skip it. */ while (*dname != '.') { if (*dname == '\\') if (*++dname == '\0') { return ISC_R_NOSPACE; } dname++; } } DPRINTF(("get_soa: out of labels")); return ISC_R_DESTADDRREQ; } static isc_result_t get_ns(res_state statp, const char *zname, ns_class class, rrset_ns *nsrrsp) { double resp[NS_PACKETSZ / sizeof (double)]; ns_msg msg; int n; isc_result_t rcode; /* Go and get the NS RRs for this zone. */ rcode = do_query(statp, zname, class, ns_t_ns, resp, &msg, &n); if (rcode != ISC_R_SUCCESS) { DPRINTF(("get_ns: do_query('zname', %s) failed (%d)", zname, p_class(class), rcode)); return rcode; } /* Remember the NS RRs and associated A RRs that came back. */ rcode = save_ns(statp, &msg, ns_s_an, zname, class, nsrrsp); if (rcode != ISC_R_SUCCESS) { DPRINTF(("get_ns save_ns('%s', %s) failed", zname, p_class(class))); return rcode; } return ISC_R_SUCCESS; } static isc_result_t get_glue(res_state statp, ns_class class, rrset_ns *nsrrsp) { rr_ns *nsrr, *nsrr_n; /* Go and get the A RRs for each empty NS RR on our list. */ for (nsrr = ISC_LIST_HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) { double resp[NS_PACKETSZ / sizeof (double)]; ns_msg msg; int n; isc_result_t rcode; nsrr_n = ISC_LIST_NEXT(nsrr, link); if (ISC_LIST_EMPTY(nsrr->addrs)) { rcode = do_query(statp, nsrr->name, class, ns_t_a, resp, &msg, &n); if (rcode != ISC_R_SUCCESS) { DPRINTF(("get_glue: do_query('%s', %s') failed", nsrr->name, p_class(class))); return rcode; } if (n > 0) { DPRINTF(( "get_glue: do_query('%s', %s') CNAME or DNAME found", nsrr->name, p_class(class))); } rcode = save_a(statp, &msg, ns_s_an, nsrr->name, class, &nsrr->addrs); if (rcode != ISC_R_SUCCESS) { DPRINTF(("get_glue: save_r('%s', %s) failed", nsrr->name, p_class(class))); return rcode; } /* If it's still empty, it's just chaff. */ if (ISC_LIST_EMPTY(nsrr->addrs)) { DPRINTF(("get_glue: removing empty '%s' NS", nsrr->name)); free_nsrr(nsrrsp, nsrr); } } } return ISC_R_SUCCESS; } static isc_result_t save_ns(res_state statp, ns_msg *msg, ns_sect sect, const char *owner, ns_class class, rrset_ns *nsrrsp) { int i; isc_result_t rcode; for (i = 0; i < ns_msg_count(*msg, sect); i++) { char tname[MAXDNAME]; const u_char *rdata; rr_ns *nsrr; ns_rr rr; int rdlen; rcode = ns_parserr(msg, sect, i, &rr); if (rcode != ISC_R_SUCCESS) { DPRINTF(("save_ns: ns_parserr(%s, %d) failed", p_section(sect, ns_o_query), i)); return rcode; } if (ns_rr_type(rr) != ns_t_ns || ns_rr_class(rr) != class || ns_samename(ns_rr_name(rr), owner) != 1) continue; nsrr = find_ns(nsrrsp, ns_rr_name(rr)); if (nsrr == NULL) { nsrr = malloc(sizeof *nsrr); if (nsrr == NULL) { DPRINTF(("save_ns: malloc failed")); return ISC_R_NOMEMORY; } rdata = ns_rr_rdata(rr); rdlen = ns_rr_rdlen(rr); if (ns_name_uncompress(ns_msg_base(*msg), ns_msg_end(*msg), rdata, tname, sizeof tname) < 0) { DPRINTF(("save_ns: ns_name_uncompress failed")); free(nsrr); return ISC_R_NOMEMORY; } nsrr->name = strdup(tname); if (nsrr->name == NULL) { DPRINTF(("save_ns: strdup failed")); free(nsrr); return ISC_R_NOMEMORY; } ISC_LIST_INIT(nsrr->addrs); ISC_LIST_APPEND(*nsrrsp, nsrr, link); } rcode = save_a(statp, msg, ns_s_ar, nsrr->name, class, &nsrr->addrs); if (rcode != ISC_R_SUCCESS) { DPRINTF(("save_ns: save_r('%s', %s) failed", nsrr->name, p_class(class))); return rcode; } } return ISC_R_SUCCESS; } static isc_result_t save_a(res_state statp, ns_msg *msg, ns_sect sect, const char *owner, ns_class class, rrset_a *arrsp) { int i; isc_result_t rcode; for (i = 0; i < ns_msg_count(*msg, sect); i++) { ns_rr rr; rr_a *arr; rcode = ns_parserr(msg, sect, i, &rr); if (rcode != ISC_R_SUCCESS) { DPRINTF(("save_a: ns_parserr(%s, %d) failed", p_section(sect, ns_o_query), i)); return rcode; } if (ns_rr_type(rr) != ns_t_a || ns_rr_class(rr) != class || ns_samename(ns_rr_name(rr), owner) != 1 || ns_rr_rdlen(rr) != NS_INADDRSZ) continue; arr = malloc(sizeof *arr); if (arr == NULL) { DPRINTF(("save_a: malloc failed")); return ISC_R_NOMEMORY; } memcpy(&arr->addr, ns_rr_rdata(rr), NS_INADDRSZ); ISC_LIST_APPEND(*arrsp, arr, link); } return ISC_R_SUCCESS; } static void free_nsrrset(rrset_ns *nsrrsp) { rr_ns *nsrr; while ((nsrr = ISC_LIST_HEAD(*nsrrsp)) != NULL) free_nsrr(nsrrsp, nsrr); } static void free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) { rr_a *arr; while ((arr = ISC_LIST_HEAD(nsrr->addrs)) != NULL) { ISC_LIST_UNLINK(nsrr->addrs, arr, link); free(arr); } free((char *)nsrr->name); ISC_LIST_UNLINK(*nsrrsp, nsrr, link); free(nsrr); } static rr_ns * find_ns(rrset_ns *nsrrsp, const char *dname) { rr_ns *nsrr; for (nsrr = ISC_LIST_HEAD(*nsrrsp); nsrr != NULL; nsrr = ISC_LIST_NEXT(nsrr, link)) if (ns_samename(nsrr->name, dname) == 1) return (nsrr); return (NULL); } static isc_result_t do_query(res_state statp, const char *dname, ns_class class, ns_type qtype, double *resp, ns_msg *msg, int *alias_count) { double req[NS_PACKETSZ / sizeof (double)]; int i; unsigned n; isc_result_t status; status = res_nmkquery(statp, ns_o_query, dname, class, qtype, NULL, 0, NULL, req, NS_PACKETSZ, &n); if (status != ISC_R_SUCCESS) { DPRINTF(("do_query: res_nmkquery failed")); return status; } status = res_nsend(statp, req, n, resp, NS_PACKETSZ, &n); if (status != ISC_R_SUCCESS) { DPRINTF(("do_query: res_nsend failed")); return status; } if (n == 0) { DPRINTF(("do_query: res_nsend returned 0")); return ISC_R_NOTFOUND; } if (ns_initparse((u_char *)resp, n, msg) < 0) { DPRINTF(("do_query: ns_initparse failed")); return ISC_R_NOSPACE; } n = 0; for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) { ns_rr rr; status = ns_parserr(msg, ns_s_an, i, &rr); if (status != ISC_R_SUCCESS) { DPRINTF(("do_query: ns_parserr failed")); return status; } n += (ns_rr_class(rr) == class && (ns_rr_type(rr) == ns_t_cname || ns_rr_type(rr) == ns_t_dname)); } if (alias_count) *alias_count = n; return ISC_R_SUCCESS; }