| /* dnsmasq is Copyright (c) 2000-2018 Simon Kelley |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; version 2 dated June, 1991, or |
| (at your option) version 3 dated 29 June, 2007. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include "dnsmasq.h" |
| |
| static struct frec *lookup_frec(unsigned short id, void *hash); |
| static struct frec *lookup_frec_by_sender(unsigned short id, |
| union mysockaddr *addr, |
| void *hash); |
| static unsigned short get_id(void); |
| static void free_frec(struct frec *f); |
| |
| /* Send a UDP packet with its source address set as "source" |
| unless nowild is true, when we just send it with the kernel default */ |
| int send_from(int fd, int nowild, char *packet, size_t len, |
| union mysockaddr *to, union all_addr *source, |
| unsigned int iface) |
| { |
| struct msghdr msg; |
| struct iovec iov[1]; |
| union { |
| struct cmsghdr align; /* this ensures alignment */ |
| #if defined(HAVE_LINUX_NETWORK) |
| char control[CMSG_SPACE(sizeof(struct in_pktinfo))]; |
| #elif defined(IP_SENDSRCADDR) |
| char control[CMSG_SPACE(sizeof(struct in_addr))]; |
| #endif |
| char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; |
| } control_u; |
| |
| iov[0].iov_base = packet; |
| iov[0].iov_len = len; |
| |
| msg.msg_control = NULL; |
| msg.msg_controllen = 0; |
| msg.msg_flags = 0; |
| msg.msg_name = to; |
| msg.msg_namelen = sa_len(to); |
| msg.msg_iov = iov; |
| msg.msg_iovlen = 1; |
| |
| if (!nowild) |
| { |
| struct cmsghdr *cmptr; |
| msg.msg_control = &control_u; |
| msg.msg_controllen = sizeof(control_u); |
| cmptr = CMSG_FIRSTHDR(&msg); |
| |
| if (to->sa.sa_family == AF_INET) |
| { |
| #if defined(HAVE_LINUX_NETWORK) |
| struct in_pktinfo p; |
| p.ipi_ifindex = 0; |
| p.ipi_spec_dst = source->addr4; |
| msg.msg_controllen = CMSG_SPACE(sizeof(struct in_pktinfo)); |
| memcpy(CMSG_DATA(cmptr), &p, sizeof(p)); |
| cmptr->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo)); |
| cmptr->cmsg_level = IPPROTO_IP; |
| cmptr->cmsg_type = IP_PKTINFO; |
| #elif defined(IP_SENDSRCADDR) |
| msg.msg_controllen = CMSG_SPACE(sizeof(struct in_addr)); |
| memcpy(CMSG_DATA(cmptr), &(source->addr4), sizeof(source->addr4)); |
| cmptr->cmsg_len = CMSG_LEN(sizeof(struct in_addr)); |
| cmptr->cmsg_level = IPPROTO_IP; |
| cmptr->cmsg_type = IP_SENDSRCADDR; |
| #endif |
| } |
| else |
| { |
| struct in6_pktinfo p; |
| p.ipi6_ifindex = iface; /* Need iface for IPv6 to handle link-local addrs */ |
| p.ipi6_addr = source->addr6; |
| msg.msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo)); |
| memcpy(CMSG_DATA(cmptr), &p, sizeof(p)); |
| cmptr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo)); |
| cmptr->cmsg_type = daemon->v6pktinfo; |
| cmptr->cmsg_level = IPPROTO_IPV6; |
| } |
| } |
| |
| while (retry_send(sendmsg(fd, &msg, 0))); |
| |
| /* If interface is still in DAD, EINVAL results - ignore that. */ |
| if (errno != 0 && errno != EINVAL) |
| { |
| my_syslog(LOG_ERR, _("failed to send packet: %s"), strerror(errno)); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static unsigned int search_servers(time_t now, union all_addr **addrpp, unsigned int qtype, |
| char *qdomain, int *type, char **domain, int *norebind) |
| |
| { |
| /* If the query ends in the domain in one of our servers, set |
| domain to point to that name. We find the largest match to allow both |
| domain.org and sub.domain.org to exist. */ |
| |
| unsigned int namelen = strlen(qdomain); |
| unsigned int matchlen = 0; |
| struct server *serv; |
| unsigned int flags = 0; |
| static union all_addr zero; |
| |
| for (serv = daemon->servers; serv; serv=serv->next) |
| if (qtype == F_DNSSECOK && !(serv->flags & SERV_DO_DNSSEC)) |
| continue; |
| /* domain matches take priority over NODOTS matches */ |
| else if ((serv->flags & SERV_FOR_NODOTS) && *type != SERV_HAS_DOMAIN && !strchr(qdomain, '.') && namelen != 0) |
| { |
| unsigned int sflag = serv->addr.sa.sa_family == AF_INET ? F_IPV4 : F_IPV6; |
| *type = SERV_FOR_NODOTS; |
| if (serv->flags & SERV_NO_ADDR) |
| flags = F_NXDOMAIN; |
| else if (serv->flags & SERV_LITERAL_ADDRESS) |
| { |
| /* literal address = '#' -> return all-zero address for IPv4 and IPv6 */ |
| if ((serv->flags & SERV_USE_RESOLV) && (qtype & (F_IPV6 | F_IPV4))) |
| { |
| memset(&zero, 0, sizeof(zero)); |
| flags = qtype; |
| *addrpp = &zero; |
| } |
| else if (sflag & qtype) |
| { |
| flags = sflag; |
| if (serv->addr.sa.sa_family == AF_INET) |
| *addrpp = (union all_addr *)&serv->addr.in.sin_addr; |
| else |
| *addrpp = (union all_addr *)&serv->addr.in6.sin6_addr; |
| } |
| else if (!flags || (flags & F_NXDOMAIN)) |
| flags = F_NOERR; |
| } |
| } |
| else if (serv->flags & SERV_HAS_DOMAIN) |
| { |
| unsigned int domainlen = strlen(serv->domain); |
| char *matchstart = qdomain + namelen - domainlen; |
| if (namelen >= domainlen && |
| hostname_isequal(matchstart, serv->domain) && |
| (domainlen == 0 || namelen == domainlen || *(matchstart-1) == '.' )) |
| { |
| if ((serv->flags & SERV_NO_REBIND) && norebind) |
| *norebind = 1; |
| else |
| { |
| unsigned int sflag = serv->addr.sa.sa_family == AF_INET ? F_IPV4 : F_IPV6; |
| /* implement priority rules for --address and --server for same domain. |
| --address wins if the address is for the correct AF |
| --server wins otherwise. */ |
| if (domainlen != 0 && domainlen == matchlen) |
| { |
| if ((serv->flags & SERV_LITERAL_ADDRESS)) |
| { |
| if (!(sflag & qtype) && flags == 0) |
| continue; |
| } |
| else |
| { |
| if (flags & (F_IPV4 | F_IPV6)) |
| continue; |
| } |
| } |
| |
| if (domainlen >= matchlen) |
| { |
| *type = serv->flags & (SERV_HAS_DOMAIN | SERV_USE_RESOLV | SERV_NO_REBIND | SERV_DO_DNSSEC); |
| *domain = serv->domain; |
| matchlen = domainlen; |
| if (serv->flags & SERV_NO_ADDR) |
| flags = F_NXDOMAIN; |
| else if (serv->flags & SERV_LITERAL_ADDRESS) |
| { |
| /* literal address = '#' -> return all-zero address for IPv4 and IPv6 */ |
| if ((serv->flags & SERV_USE_RESOLV) && (qtype & (F_IPV6 | F_IPV4))) |
| { |
| memset(&zero, 0, sizeof(zero)); |
| flags = qtype; |
| *addrpp = &zero; |
| } |
| else if (sflag & qtype) |
| { |
| flags = sflag; |
| if (serv->addr.sa.sa_family == AF_INET) |
| *addrpp = (union all_addr *)&serv->addr.in.sin_addr; |
| else |
| *addrpp = (union all_addr *)&serv->addr.in6.sin6_addr; |
| } |
| else if (!flags || (flags & F_NXDOMAIN)) |
| flags = F_NOERR; |
| } |
| else |
| flags = 0; |
| } |
| } |
| } |
| } |
| |
| if (flags == 0 && !(qtype & (F_QUERY | F_DNSSECOK)) && |
| option_bool(OPT_NODOTS_LOCAL) && !strchr(qdomain, '.') && namelen != 0) |
| /* don't forward A or AAAA queries for simple names, except the empty name */ |
| flags = F_NOERR; |
| |
| if (flags == F_NXDOMAIN && check_for_local_domain(qdomain, now)) |
| flags = F_NOERR; |
| |
| if (flags) |
| { |
| if (flags == F_NXDOMAIN || flags == F_NOERR) |
| log_query(flags | qtype | F_NEG | F_CONFIG | F_FORWARD, qdomain, NULL, NULL); |
| else |
| { |
| /* handle F_IPV4 and F_IPV6 set on ANY query to 0.0.0.0/:: domain. */ |
| if (flags & F_IPV4) |
| log_query((flags | F_CONFIG | F_FORWARD) & ~F_IPV6, qdomain, *addrpp, NULL); |
| if (flags & F_IPV6) |
| log_query((flags | F_CONFIG | F_FORWARD) & ~F_IPV4, qdomain, *addrpp, NULL); |
| } |
| } |
| else if ((*type) & SERV_USE_RESOLV) |
| { |
| *type = 0; /* use normal servers for this domain */ |
| *domain = NULL; |
| } |
| return flags; |
| } |
| |
| static int forward_query(int udpfd, union mysockaddr *udpaddr, |
| union all_addr *dst_addr, unsigned int dst_iface, |
| struct dns_header *header, size_t plen, time_t now, |
| struct frec *forward, int ad_reqd, int do_bit) |
| { |
| char *domain = NULL; |
| int type = SERV_DO_DNSSEC, norebind = 0; |
| union all_addr *addrp = NULL; |
| unsigned int flags = 0; |
| struct server *start = NULL; |
| #ifdef HAVE_DNSSEC |
| void *hash = hash_questions(header, plen, daemon->namebuff); |
| int do_dnssec = 0; |
| #else |
| unsigned int crc = questions_crc(header, plen, daemon->namebuff); |
| void *hash = &crc; |
| #endif |
| unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL); |
| unsigned char *oph = find_pseudoheader(header, plen, NULL, NULL, NULL, NULL); |
| (void)do_bit; |
| |
| /* may be no servers available. */ |
| if (forward || (hash && (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, hash)))) |
| { |
| /* If we didn't get an answer advertising a maximal packet in EDNS, |
| fall back to 1280, which should work everywhere on IPv6. |
| If that generates an answer, it will become the new default |
| for this server */ |
| forward->flags |= FREC_TEST_PKTSZ; |
| |
| #ifdef HAVE_DNSSEC |
| /* If we've already got an answer to this query, but we're awaiting keys for validation, |
| there's no point retrying the query, retry the key query instead...... */ |
| if (forward->blocking_query) |
| { |
| int fd, is_sign; |
| unsigned char *pheader; |
| |
| forward->flags &= ~FREC_TEST_PKTSZ; |
| |
| while (forward->blocking_query) |
| forward = forward->blocking_query; |
| |
| blockdata_retrieve(forward->stash, forward->stash_len, (void *)header); |
| plen = forward->stash_len; |
| |
| forward->flags |= FREC_TEST_PKTSZ; |
| if (find_pseudoheader(header, plen, NULL, &pheader, &is_sign, NULL) && !is_sign) |
| PUTSHORT(SAFE_PKTSZ, pheader); |
| |
| if (forward->sentto->addr.sa.sa_family == AF_INET) |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV4, "retry", (union all_addr *)&forward->sentto->addr.in.sin_addr, "dnssec"); |
| else |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV6, "retry", (union all_addr *)&forward->sentto->addr.in6.sin6_addr, "dnssec"); |
| |
| |
| if (forward->sentto->sfd) |
| fd = forward->sentto->sfd->fd; |
| else |
| { |
| if (forward->sentto->addr.sa.sa_family == AF_INET6) |
| fd = forward->rfd6->fd; |
| else |
| fd = forward->rfd4->fd; |
| } |
| |
| while (retry_send(sendto(fd, (char *)header, plen, 0, |
| &forward->sentto->addr.sa, |
| sa_len(&forward->sentto->addr)))); |
| |
| return 1; |
| } |
| #endif |
| |
| /* retry on existing query, send to all available servers */ |
| domain = forward->sentto->domain; |
| forward->sentto->failed_queries++; |
| if (!option_bool(OPT_ORDER)) |
| { |
| forward->forwardall = 1; |
| daemon->last_server = NULL; |
| } |
| type = forward->sentto->flags & SERV_TYPE; |
| #ifdef HAVE_DNSSEC |
| do_dnssec = forward->sentto->flags & SERV_DO_DNSSEC; |
| #endif |
| |
| if (!(start = forward->sentto->next)) |
| start = daemon->servers; /* at end of list, recycle */ |
| header->id = htons(forward->new_id); |
| } |
| else |
| { |
| if (gotname) |
| flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind); |
| |
| #ifdef HAVE_DNSSEC |
| do_dnssec = type & SERV_DO_DNSSEC; |
| #endif |
| type &= ~SERV_DO_DNSSEC; |
| |
| if (daemon->servers && !flags) |
| forward = get_new_frec(now, NULL, 0); |
| /* table full - flags == 0, return REFUSED */ |
| |
| if (forward) |
| { |
| forward->source = *udpaddr; |
| forward->dest = *dst_addr; |
| forward->iface = dst_iface; |
| forward->orig_id = ntohs(header->id); |
| forward->new_id = get_id(); |
| forward->fd = udpfd; |
| memcpy(forward->hash, hash, HASH_SIZE); |
| forward->forwardall = 0; |
| forward->flags = 0; |
| if (norebind) |
| forward->flags |= FREC_NOREBIND; |
| if (header->hb4 & HB4_CD) |
| forward->flags |= FREC_CHECKING_DISABLED; |
| if (ad_reqd) |
| forward->flags |= FREC_AD_QUESTION; |
| #ifdef HAVE_DNSSEC |
| forward->work_counter = DNSSEC_WORK; |
| if (do_bit) |
| forward->flags |= FREC_DO_QUESTION; |
| #endif |
| |
| header->id = htons(forward->new_id); |
| |
| /* In strict_order mode, always try servers in the order |
| specified in resolv.conf, if a domain is given |
| always try all the available servers, |
| otherwise, use the one last known to work. */ |
| |
| if (type == 0) |
| { |
| if (option_bool(OPT_ORDER)) |
| start = daemon->servers; |
| else if (!(start = daemon->last_server) || |
| daemon->forwardcount++ > FORWARD_TEST || |
| difftime(now, daemon->forwardtime) > FORWARD_TIME) |
| { |
| start = daemon->servers; |
| forward->forwardall = 1; |
| daemon->forwardcount = 0; |
| daemon->forwardtime = now; |
| } |
| } |
| else |
| { |
| start = daemon->servers; |
| if (!option_bool(OPT_ORDER)) |
| forward->forwardall = 1; |
| } |
| } |
| } |
| |
| /* check for send errors here (no route to host) |
| if we fail to send to all nameservers, send back an error |
| packet straight away (helps modem users when offline) */ |
| |
| if (!flags && forward) |
| { |
| struct server *firstsentto = start; |
| int subnet, forwarded = 0; |
| size_t edns0_len; |
| unsigned char *pheader; |
| |
| /* If a query is retried, use the log_id for the retry when logging the answer. */ |
| forward->log_id = daemon->log_id; |
| |
| plen = add_edns0_config(header, plen, ((unsigned char *)header) + PACKETSZ, &forward->source, now, &subnet); |
| |
| if (subnet) |
| forward->flags |= FREC_HAS_SUBNET; |
| |
| #ifdef HAVE_DNSSEC |
| if (option_bool(OPT_DNSSEC_VALID) && do_dnssec) |
| { |
| plen = add_do_bit(header, plen, ((unsigned char *) header) + PACKETSZ); |
| |
| /* For debugging, set Checking Disabled, otherwise, have the upstream check too, |
| this allows it to select auth servers when one is returning bad data. */ |
| if (option_bool(OPT_DNSSEC_DEBUG)) |
| header->hb4 |= HB4_CD; |
| |
| } |
| #endif |
| |
| if (find_pseudoheader(header, plen, &edns0_len, &pheader, NULL, NULL)) |
| { |
| /* If there wasn't a PH before, and there is now, we added it. */ |
| if (!oph) |
| forward->flags |= FREC_ADDED_PHEADER; |
| |
| /* If we're sending an EDNS0 with any options, we can't recreate the query from a reply. */ |
| if (edns0_len > 11) |
| forward->flags |= FREC_HAS_EXTRADATA; |
| |
| /* Reduce udp size on retransmits. */ |
| if (forward->flags & FREC_TEST_PKTSZ) |
| PUTSHORT(SAFE_PKTSZ, pheader); |
| } |
| |
| while (1) |
| { |
| /* only send to servers dealing with our domain. |
| domain may be NULL, in which case server->domain |
| must be NULL also. */ |
| |
| if (type == (start->flags & SERV_TYPE) && |
| (type != SERV_HAS_DOMAIN || hostname_isequal(domain, start->domain)) && |
| !(start->flags & (SERV_LITERAL_ADDRESS | SERV_LOOP))) |
| { |
| int fd; |
| |
| /* find server socket to use, may need to get random one. */ |
| if (start->sfd) |
| fd = start->sfd->fd; |
| else |
| { |
| if (start->addr.sa.sa_family == AF_INET6) |
| { |
| if (!forward->rfd6 && |
| !(forward->rfd6 = allocate_rfd(AF_INET6))) |
| break; |
| daemon->rfd_save = forward->rfd6; |
| fd = forward->rfd6->fd; |
| } |
| else |
| { |
| if (!forward->rfd4 && |
| !(forward->rfd4 = allocate_rfd(AF_INET))) |
| break; |
| daemon->rfd_save = forward->rfd4; |
| fd = forward->rfd4->fd; |
| } |
| |
| #ifdef HAVE_CONNTRACK |
| /* Copy connection mark of incoming query to outgoing connection. */ |
| if (option_bool(OPT_CONNTRACK)) |
| { |
| unsigned int mark; |
| if (get_incoming_mark(&forward->source, &forward->dest, 0, &mark)) |
| setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int)); |
| } |
| #endif |
| } |
| |
| #ifdef HAVE_DNSSEC |
| if (option_bool(OPT_DNSSEC_VALID) && (forward->flags & FREC_ADDED_PHEADER)) |
| { |
| /* Difficult one here. If our client didn't send EDNS0, we will have set the UDP |
| packet size to 512. But that won't provide space for the RRSIGS in many cases. |
| The RRSIGS will be stripped out before the answer goes back, so the packet should |
| shrink again. So, if we added a do-bit, bump the udp packet size to the value |
| known to be OK for this server. We check returned size after stripping and set |
| the truncated bit if it's still too big. */ |
| unsigned char *pheader; |
| int is_sign; |
| if (find_pseudoheader(header, plen, NULL, &pheader, &is_sign, NULL) && !is_sign) |
| PUTSHORT(start->edns_pktsz, pheader); |
| } |
| #endif |
| |
| if (retry_send(sendto(fd, (char *)header, plen, 0, |
| &start->addr.sa, |
| sa_len(&start->addr)))) |
| continue; |
| |
| if (errno == 0) |
| { |
| #ifdef HAVE_DUMPFILE |
| dump_packet(DUMP_UP_QUERY, (void *)header, plen, NULL, &start->addr); |
| #endif |
| |
| /* Keep info in case we want to re-send this packet */ |
| daemon->srv_save = start; |
| daemon->packet_len = plen; |
| |
| if (!gotname) |
| strcpy(daemon->namebuff, "query"); |
| if (start->addr.sa.sa_family == AF_INET) |
| log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&start->addr.in.sin_addr, NULL); |
| else |
| log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&start->addr.in6.sin6_addr, NULL); |
| start->queries++; |
| forwarded = 1; |
| forward->sentto = start; |
| if (!forward->forwardall) |
| break; |
| forward->forwardall++; |
| } |
| } |
| |
| if (!(start = start->next)) |
| start = daemon->servers; |
| |
| if (start == firstsentto) |
| break; |
| } |
| |
| if (forwarded) |
| return 1; |
| |
| /* could not send on, prepare to return */ |
| header->id = htons(forward->orig_id); |
| free_frec(forward); /* cancel */ |
| } |
| |
| /* could not send on, return empty answer or address if known for whole domain */ |
| if (udpfd != -1) |
| { |
| plen = setup_reply(header, plen, addrp, flags, daemon->local_ttl); |
| if (oph) |
| plen = add_pseudoheader(header, plen, ((unsigned char *) header) + PACKETSZ, daemon->edns_pktsz, 0, NULL, 0, do_bit, 0); |
| send_from(udpfd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), (char *)header, plen, udpaddr, dst_addr, dst_iface); |
| } |
| |
| return 0; |
| } |
| |
| static size_t process_reply(struct dns_header *header, time_t now, struct server *server, size_t n, int check_rebind, |
| int no_cache, int cache_secure, int bogusanswer, int ad_reqd, int do_bit, int added_pheader, |
| int check_subnet, union mysockaddr *query_source) |
| { |
| unsigned char *pheader, *sizep; |
| char **sets = 0; |
| int munged = 0, is_sign; |
| unsigned int rcode = RCODE(header); |
| size_t plen; |
| |
| (void)ad_reqd; |
| (void)do_bit; |
| (void)bogusanswer; |
| |
| #ifdef HAVE_IPSET |
| if (daemon->ipsets && extract_request(header, n, daemon->namebuff, NULL)) |
| { |
| /* Similar algorithm to search_servers. */ |
| struct ipsets *ipset_pos; |
| unsigned int namelen = strlen(daemon->namebuff); |
| unsigned int matchlen = 0; |
| for (ipset_pos = daemon->ipsets; ipset_pos; ipset_pos = ipset_pos->next) |
| { |
| unsigned int domainlen = strlen(ipset_pos->domain); |
| char *matchstart = daemon->namebuff + namelen - domainlen; |
| if (namelen >= domainlen && hostname_isequal(matchstart, ipset_pos->domain) && |
| (domainlen == 0 || namelen == domainlen || *(matchstart - 1) == '.' ) && |
| domainlen >= matchlen) |
| { |
| matchlen = domainlen; |
| sets = ipset_pos->sets; |
| } |
| } |
| } |
| #endif |
| |
| if ((pheader = find_pseudoheader(header, n, &plen, &sizep, &is_sign, NULL))) |
| { |
| /* Get extended RCODE. */ |
| rcode |= sizep[2] << 4; |
| |
| if (check_subnet && !check_source(header, plen, pheader, query_source)) |
| { |
| my_syslog(LOG_WARNING, _("discarding DNS reply: subnet option mismatch")); |
| return 0; |
| } |
| |
| if (!is_sign) |
| { |
| if (added_pheader) |
| { |
| /* client didn't send EDNS0, we added one, strip it off before returning answer. */ |
| n = rrfilter(header, n, 0); |
| pheader = NULL; |
| } |
| else |
| { |
| unsigned short udpsz; |
| |
| /* If upstream is advertising a larger UDP packet size |
| than we allow, trim it so that we don't get overlarge |
| requests for the client. We can't do this for signed packets. */ |
| GETSHORT(udpsz, sizep); |
| if (udpsz > daemon->edns_pktsz) |
| { |
| sizep -= 2; |
| PUTSHORT(daemon->edns_pktsz, sizep); |
| } |
| |
| #ifdef HAVE_DNSSEC |
| /* If the client didn't set the do bit, but we did, reset it. */ |
| if (option_bool(OPT_DNSSEC_VALID) && !do_bit) |
| { |
| unsigned short flags; |
| sizep += 2; /* skip RCODE */ |
| GETSHORT(flags, sizep); |
| flags &= ~0x8000; |
| sizep -= 2; |
| PUTSHORT(flags, sizep); |
| } |
| #endif |
| } |
| } |
| } |
| |
| /* RFC 4035 sect 4.6 para 3 */ |
| if (!is_sign && !option_bool(OPT_DNSSEC_PROXY)) |
| header->hb4 &= ~HB4_AD; |
| |
| if (OPCODE(header) != QUERY) |
| return resize_packet(header, n, pheader, plen); |
| |
| if (rcode != NOERROR && rcode != NXDOMAIN) |
| { |
| union all_addr a; |
| a.log.rcode = rcode; |
| log_query(F_UPSTREAM | F_RCODE, "error", &a, NULL); |
| |
| return resize_packet(header, n, pheader, plen); |
| } |
| |
| /* Complain loudly if the upstream server is non-recursive. */ |
| if (!(header->hb4 & HB4_RA) && rcode == NOERROR && |
| server && !(server->flags & SERV_WARNED_RECURSIVE)) |
| { |
| prettyprint_addr(&server->addr, daemon->namebuff); |
| my_syslog(LOG_WARNING, _("nameserver %s refused to do a recursive query"), daemon->namebuff); |
| if (!option_bool(OPT_LOG)) |
| server->flags |= SERV_WARNED_RECURSIVE; |
| } |
| |
| if (daemon->bogus_addr && rcode != NXDOMAIN && |
| check_for_bogus_wildcard(header, n, daemon->namebuff, daemon->bogus_addr, now)) |
| { |
| munged = 1; |
| SET_RCODE(header, NXDOMAIN); |
| header->hb3 &= ~HB3_AA; |
| cache_secure = 0; |
| } |
| else |
| { |
| int doctored = 0; |
| |
| if (rcode == NXDOMAIN && |
| extract_request(header, n, daemon->namebuff, NULL) && |
| check_for_local_domain(daemon->namebuff, now)) |
| { |
| /* if we forwarded a query for a locally known name (because it was for |
| an unknown type) and the answer is NXDOMAIN, convert that to NODATA, |
| since we know that the domain exists, even if upstream doesn't */ |
| munged = 1; |
| header->hb3 |= HB3_AA; |
| SET_RCODE(header, NOERROR); |
| cache_secure = 0; |
| } |
| |
| if (extract_addresses(header, n, daemon->namebuff, now, sets, is_sign, check_rebind, no_cache, cache_secure, &doctored)) |
| { |
| my_syslog(LOG_WARNING, _("possible DNS-rebind attack detected: %s"), daemon->namebuff); |
| munged = 1; |
| cache_secure = 0; |
| } |
| |
| if (doctored) |
| cache_secure = 0; |
| } |
| |
| #ifdef HAVE_DNSSEC |
| if (bogusanswer && !(header->hb4 & HB4_CD) && !option_bool(OPT_DNSSEC_DEBUG)) |
| { |
| /* Bogus reply, turn into SERVFAIL */ |
| SET_RCODE(header, SERVFAIL); |
| munged = 1; |
| } |
| |
| if (option_bool(OPT_DNSSEC_VALID)) |
| { |
| header->hb4 &= ~HB4_AD; |
| |
| if (!(header->hb4 & HB4_CD) && ad_reqd && cache_secure) |
| header->hb4 |= HB4_AD; |
| |
| /* If the requestor didn't set the DO bit, don't return DNSSEC info. */ |
| if (!do_bit) |
| n = rrfilter(header, n, 1); |
| } |
| #endif |
| |
| /* do this after extract_addresses. Ensure NODATA reply and remove |
| nameserver info. */ |
| |
| if (munged) |
| { |
| header->ancount = htons(0); |
| header->nscount = htons(0); |
| header->arcount = htons(0); |
| header->hb3 &= ~HB3_TC; |
| } |
| |
| /* the bogus-nxdomain stuff, doctor and NXDOMAIN->NODATA munging can all elide |
| sections of the packet. Find the new length here and put back pseudoheader |
| if it was removed. */ |
| return resize_packet(header, n, pheader, plen); |
| } |
| |
| /* sets new last_server */ |
| void reply_query(int fd, int family, time_t now) |
| { |
| /* packet from peer server, extract data for cache, and send to |
| original requester */ |
| struct dns_header *header; |
| union mysockaddr serveraddr; |
| struct frec *forward; |
| socklen_t addrlen = sizeof(serveraddr); |
| ssize_t n = recvfrom(fd, daemon->packet, daemon->packet_buff_sz, 0, &serveraddr.sa, &addrlen); |
| size_t nn; |
| struct server *server; |
| void *hash; |
| #ifndef HAVE_DNSSEC |
| unsigned int crc; |
| #endif |
| |
| /* packet buffer overwritten */ |
| daemon->srv_save = NULL; |
| |
| /* Determine the address of the server replying so that we can mark that as good */ |
| if ((serveraddr.sa.sa_family = family) == AF_INET6) |
| serveraddr.in6.sin6_flowinfo = 0; |
| |
| header = (struct dns_header *)daemon->packet; |
| |
| if (n < (int)sizeof(struct dns_header) || !(header->hb3 & HB3_QR)) |
| return; |
| |
| /* spoof check: answer must come from known server, */ |
| for (server = daemon->servers; server; server = server->next) |
| if (!(server->flags & (SERV_LITERAL_ADDRESS | SERV_NO_ADDR)) && |
| sockaddr_isequal(&server->addr, &serveraddr)) |
| break; |
| |
| if (!server) |
| return; |
| |
| /* If sufficient time has elapsed, try and expand UDP buffer size again. */ |
| if (difftime(now, server->pktsz_reduced) > UDP_TEST_TIME) |
| server->edns_pktsz = daemon->edns_pktsz; |
| |
| #ifdef HAVE_DNSSEC |
| hash = hash_questions(header, n, daemon->namebuff); |
| #else |
| hash = &crc; |
| crc = questions_crc(header, n, daemon->namebuff); |
| #endif |
| |
| if (!(forward = lookup_frec(ntohs(header->id), hash))) |
| return; |
| |
| #ifdef HAVE_DUMPFILE |
| dump_packet((forward->flags & (FREC_DNSKEY_QUERY | FREC_DS_QUERY)) ? DUMP_SEC_REPLY : DUMP_UP_REPLY, |
| (void *)header, n, &serveraddr, NULL); |
| #endif |
| |
| /* log_query gets called indirectly all over the place, so |
| pass these in global variables - sorry. */ |
| daemon->log_display_id = forward->log_id; |
| daemon->log_source_addr = &forward->source; |
| |
| if (daemon->ignore_addr && RCODE(header) == NOERROR && |
| check_for_ignored_address(header, n, daemon->ignore_addr)) |
| return; |
| |
| /* Note: if we send extra options in the EDNS0 header, we can't recreate |
| the query from the reply. */ |
| if ((RCODE(header) == REFUSED || RCODE(header) == SERVFAIL) && |
| forward->forwardall == 0 && |
| !(forward->flags & FREC_HAS_EXTRADATA)) |
| /* for broken servers, attempt to send to another one. */ |
| { |
| unsigned char *pheader; |
| size_t plen; |
| int is_sign; |
| |
| #ifdef HAVE_DNSSEC |
| /* For DNSSEC originated queries, just retry the query to the same server. */ |
| if (forward->flags & (FREC_DNSKEY_QUERY | FREC_DS_QUERY)) |
| { |
| struct server *start; |
| |
| blockdata_retrieve(forward->stash, forward->stash_len, (void *)header); |
| plen = forward->stash_len; |
| |
| forward->forwardall = 2; /* only retry once */ |
| start = forward->sentto; |
| |
| /* for non-domain specific servers, see if we can find another to try. */ |
| if ((forward->sentto->flags & SERV_TYPE) == 0) |
| while (1) |
| { |
| if (!(start = start->next)) |
| start = daemon->servers; |
| if (start == forward->sentto) |
| break; |
| |
| if ((start->flags & SERV_TYPE) == 0 && |
| (start->flags & SERV_DO_DNSSEC)) |
| break; |
| } |
| |
| |
| if (start->sfd) |
| fd = start->sfd->fd; |
| else |
| { |
| if (start->addr.sa.sa_family == AF_INET6) |
| { |
| /* may have changed family */ |
| if (!forward->rfd6) |
| forward->rfd6 = allocate_rfd(AF_INET6); |
| fd = forward->rfd6->fd; |
| } |
| else |
| { |
| /* may have changed family */ |
| if (!forward->rfd4) |
| forward->rfd4 = allocate_rfd(AF_INET); |
| fd = forward->rfd4->fd; |
| } |
| } |
| |
| #ifdef HAVE_DUMPFILE |
| dump_packet(DUMP_SEC_QUERY, (void *)header, (size_t)plen, NULL, &start->addr); |
| #endif |
| |
| while (retry_send(sendto(fd, (char *)header, plen, 0, |
| &start->addr.sa, |
| sa_len(&start->addr)))); |
| |
| if (start->addr.sa.sa_family == AF_INET) |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV4, "retry", (union all_addr *)&start->addr.in.sin_addr, "dnssec"); |
| else |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV6, "retry", (union all_addr *)&start->addr.in6.sin6_addr, "dnssec"); |
| |
| return; |
| } |
| #endif |
| |
| /* In strict order mode, there must be a server later in the chain |
| left to send to, otherwise without the forwardall mechanism, |
| code further on will cycle around the list forwever if they |
| all return REFUSED. Note that server is always non-NULL before |
| this executes. */ |
| if (option_bool(OPT_ORDER)) |
| for (server = forward->sentto->next; server; server = server->next) |
| if (!(server->flags & (SERV_LITERAL_ADDRESS | SERV_HAS_DOMAIN | SERV_FOR_NODOTS | SERV_NO_ADDR | SERV_LOOP))) |
| break; |
| |
| /* recreate query from reply */ |
| pheader = find_pseudoheader(header, (size_t)n, &plen, NULL, &is_sign, NULL); |
| if (!is_sign && server) |
| { |
| header->ancount = htons(0); |
| header->nscount = htons(0); |
| header->arcount = htons(0); |
| if ((nn = resize_packet(header, (size_t)n, pheader, plen))) |
| { |
| header->hb3 &= ~(HB3_QR | HB3_AA | HB3_TC); |
| header->hb4 &= ~(HB4_RA | HB4_RCODE | HB4_CD | HB4_AD); |
| if (forward->flags & FREC_CHECKING_DISABLED) |
| header->hb4 |= HB4_CD; |
| if (forward->flags & FREC_AD_QUESTION) |
| header->hb4 |= HB4_AD; |
| if (forward->flags & FREC_DO_QUESTION) |
| add_do_bit(header, nn, (unsigned char *)pheader + plen); |
| forward_query(-1, NULL, NULL, 0, header, nn, now, forward, forward->flags & FREC_AD_QUESTION, forward->flags & FREC_DO_QUESTION); |
| return; |
| } |
| } |
| } |
| |
| server = forward->sentto; |
| if ((forward->sentto->flags & SERV_TYPE) == 0) |
| { |
| if (RCODE(header) == REFUSED) |
| server = NULL; |
| else |
| { |
| struct server *last_server; |
| |
| /* find good server by address if possible, otherwise assume the last one we sent to */ |
| for (last_server = daemon->servers; last_server; last_server = last_server->next) |
| if (!(last_server->flags & (SERV_LITERAL_ADDRESS | SERV_HAS_DOMAIN | SERV_FOR_NODOTS | SERV_NO_ADDR)) && |
| sockaddr_isequal(&last_server->addr, &serveraddr)) |
| { |
| server = last_server; |
| break; |
| } |
| } |
| if (!option_bool(OPT_ALL_SERVERS)) |
| daemon->last_server = server; |
| } |
| |
| /* We tried resending to this server with a smaller maximum size and got an answer. |
| Make that permanent. To avoid reduxing the packet size for a single dropped packet, |
| only do this when we get a truncated answer, or one larger than the safe size. */ |
| if (forward->sentto->edns_pktsz > SAFE_PKTSZ && (forward->flags & FREC_TEST_PKTSZ) && |
| ((header->hb3 & HB3_TC) || n >= SAFE_PKTSZ)) |
| { |
| forward->sentto->edns_pktsz = SAFE_PKTSZ; |
| forward->sentto->pktsz_reduced = now; |
| prettyprint_addr(&forward->sentto->addr, daemon->addrbuff); |
| my_syslog(LOG_WARNING, _("reducing DNS packet size for nameserver %s to %d"), daemon->addrbuff, SAFE_PKTSZ); |
| } |
| |
| |
| /* If the answer is an error, keep the forward record in place in case |
| we get a good reply from another server. Kill it when we've |
| had replies from all to avoid filling the forwarding table when |
| everything is broken */ |
| if (forward->forwardall == 0 || --forward->forwardall == 1 || RCODE(header) != REFUSED) |
| { |
| int check_rebind = 0, no_cache_dnssec = 0, cache_secure = 0, bogusanswer = 0; |
| |
| if (option_bool(OPT_NO_REBIND)) |
| check_rebind = !(forward->flags & FREC_NOREBIND); |
| |
| /* Don't cache replies where DNSSEC validation was turned off, either |
| the upstream server told us so, or the original query specified it. */ |
| if ((header->hb4 & HB4_CD) || (forward->flags & FREC_CHECKING_DISABLED)) |
| no_cache_dnssec = 1; |
| |
| #ifdef HAVE_DNSSEC |
| if ((forward->sentto->flags & SERV_DO_DNSSEC) && |
| option_bool(OPT_DNSSEC_VALID) && !(forward->flags & FREC_CHECKING_DISABLED)) |
| { |
| int status = 0; |
| |
| /* We've had a reply already, which we're validating. Ignore this duplicate */ |
| if (forward->blocking_query) |
| return; |
| |
| /* Truncated answer can't be validated. |
| If this is an answer to a DNSSEC-generated query, we still |
| need to get the client to retry over TCP, so return |
| an answer with the TC bit set, even if the actual answer fits. |
| */ |
| if (header->hb3 & HB3_TC) |
| status = STAT_TRUNCATED; |
| |
| while (1) |
| { |
| /* As soon as anything returns BOGUS, we stop and unwind, to do otherwise |
| would invite infinite loops, since the answers to DNSKEY and DS queries |
| will not be cached, so they'll be repeated. */ |
| if (status != STAT_BOGUS && status != STAT_TRUNCATED && status != STAT_ABANDONED) |
| { |
| if (forward->flags & FREC_DNSKEY_QUERY) |
| status = dnssec_validate_by_ds(now, header, n, daemon->namebuff, daemon->keyname, forward->class); |
| else if (forward->flags & FREC_DS_QUERY) |
| status = dnssec_validate_ds(now, header, n, daemon->namebuff, daemon->keyname, forward->class); |
| else |
| status = dnssec_validate_reply(now, header, n, daemon->namebuff, daemon->keyname, &forward->class, |
| !option_bool(OPT_DNSSEC_IGN_NS) && (forward->sentto->flags & SERV_DO_DNSSEC), |
| NULL, NULL, NULL); |
| #ifdef HAVE_DUMPFILE |
| if (status == STAT_BOGUS) |
| dump_packet((forward->flags & (FREC_DNSKEY_QUERY | FREC_DS_QUERY)) ? DUMP_SEC_BOGUS : DUMP_BOGUS, |
| header, (size_t)n, &serveraddr, NULL); |
| #endif |
| } |
| |
| /* Can't validate, as we're missing key data. Put this |
| answer aside, whilst we get that. */ |
| if (status == STAT_NEED_DS || status == STAT_NEED_KEY) |
| { |
| struct frec *new, *orig; |
| |
| /* Free any saved query */ |
| if (forward->stash) |
| blockdata_free(forward->stash); |
| |
| /* Now save reply pending receipt of key data */ |
| if (!(forward->stash = blockdata_alloc((char *)header, n))) |
| return; |
| forward->stash_len = n; |
| |
| /* Find the original query that started it all.... */ |
| for (orig = forward; orig->dependent; orig = orig->dependent); |
| |
| if (--orig->work_counter == 0 || !(new = get_new_frec(now, NULL, 1))) |
| status = STAT_ABANDONED; |
| else |
| { |
| int querytype, fd, type = SERV_DO_DNSSEC; |
| struct frec *next = new->next; |
| char *domain; |
| |
| *new = *forward; /* copy everything, then overwrite */ |
| new->next = next; |
| new->blocking_query = NULL; |
| |
| /* Find server to forward to. This will normally be the |
| same as for the original query, but may be another if |
| servers for domains are involved. */ |
| if (search_servers(now, NULL, F_DNSSECOK, daemon->keyname, &type, &domain, NULL) == 0) |
| { |
| struct server *start, *new_server = NULL; |
| start = server = forward->sentto; |
| |
| while (1) |
| { |
| if (type == (start->flags & (SERV_TYPE | SERV_DO_DNSSEC)) && |
| ((type & SERV_TYPE) != SERV_HAS_DOMAIN || hostname_isequal(domain, start->domain)) && |
| !(start->flags & (SERV_LITERAL_ADDRESS | SERV_LOOP))) |
| { |
| new_server = start; |
| if (server == start) |
| { |
| new_server = NULL; |
| break; |
| } |
| } |
| |
| if (!(start = start->next)) |
| start = daemon->servers; |
| if (start == server) |
| break; |
| } |
| |
| if (new_server) |
| server = new_server; |
| } |
| |
| new->sentto = server; |
| new->rfd4 = NULL; |
| new->rfd6 = NULL; |
| new->flags &= ~(FREC_DNSKEY_QUERY | FREC_DS_QUERY | FREC_HAS_EXTRADATA); |
| new->forwardall = 0; |
| |
| new->dependent = forward; /* to find query awaiting new one. */ |
| forward->blocking_query = new; /* for garbage cleaning */ |
| /* validate routines leave name of required record in daemon->keyname */ |
| if (status == STAT_NEED_KEY) |
| { |
| new->flags |= FREC_DNSKEY_QUERY; |
| querytype = T_DNSKEY; |
| } |
| else |
| { |
| new->flags |= FREC_DS_QUERY; |
| querytype = T_DS; |
| } |
| |
| nn = dnssec_generate_query(header,((unsigned char *) header) + server->edns_pktsz, |
| daemon->keyname, forward->class, querytype, server->edns_pktsz); |
| |
| if (server->addr.sa.sa_family == AF_INET) |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV4, daemon->keyname, (union all_addr *)&(server->addr.in.sin_addr), |
| querystr("dnssec-query", querytype)); |
| else |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV6, daemon->keyname, (union all_addr *)&(server->addr.in6.sin6_addr), |
| querystr("dnssec-query", querytype)); |
| |
| if ((hash = hash_questions(header, nn, daemon->namebuff))) |
| memcpy(new->hash, hash, HASH_SIZE); |
| new->new_id = get_id(); |
| header->id = htons(new->new_id); |
| /* Save query for retransmission */ |
| new->stash = blockdata_alloc((char *)header, nn); |
| new->stash_len = nn; |
| |
| /* Don't resend this. */ |
| daemon->srv_save = NULL; |
| |
| if (server->sfd) |
| fd = server->sfd->fd; |
| else |
| { |
| fd = -1; |
| if (server->addr.sa.sa_family == AF_INET6) |
| { |
| if (new->rfd6 || (new->rfd6 = allocate_rfd(AF_INET6))) |
| fd = new->rfd6->fd; |
| } |
| else |
| { |
| if (new->rfd4 || (new->rfd4 = allocate_rfd(AF_INET))) |
| fd = new->rfd4->fd; |
| } |
| } |
| |
| if (fd != -1) |
| { |
| #ifdef HAVE_CONNTRACK |
| /* Copy connection mark of incoming query to outgoing connection. */ |
| if (option_bool(OPT_CONNTRACK)) |
| { |
| unsigned int mark; |
| if (get_incoming_mark(&orig->source, &orig->dest, 0, &mark)) |
| setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int)); |
| } |
| #endif |
| |
| #ifdef HAVE_DUMPFILE |
| dump_packet(DUMP_SEC_QUERY, (void *)header, (size_t)nn, NULL, &server->addr); |
| #endif |
| |
| while (retry_send(sendto(fd, (char *)header, nn, 0, |
| &server->addr.sa, |
| sa_len(&server->addr)))); |
| server->queries++; |
| } |
| } |
| return; |
| } |
| |
| /* Validated original answer, all done. */ |
| if (!forward->dependent) |
| break; |
| |
| /* validated subsidiary query, (and cached result) |
| pop that and return to the previous query we were working on. */ |
| struct frec *prev = forward->dependent; |
| free_frec(forward); |
| forward = prev; |
| forward->blocking_query = NULL; /* already gone */ |
| blockdata_retrieve(forward->stash, forward->stash_len, (void *)header); |
| n = forward->stash_len; |
| } |
| |
| |
| no_cache_dnssec = 0; |
| |
| if (status == STAT_TRUNCATED) |
| header->hb3 |= HB3_TC; |
| else |
| { |
| char *result, *domain = "result"; |
| |
| if (status == STAT_ABANDONED) |
| { |
| result = "ABANDONED"; |
| status = STAT_BOGUS; |
| } |
| else |
| result = (status == STAT_SECURE ? "SECURE" : (status == STAT_INSECURE ? "INSECURE" : "BOGUS")); |
| |
| if (status == STAT_BOGUS && extract_request(header, n, daemon->namebuff, NULL)) |
| domain = daemon->namebuff; |
| |
| log_query(F_SECSTAT, domain, NULL, result); |
| } |
| |
| if (status == STAT_SECURE) |
| cache_secure = 1; |
| else if (status == STAT_BOGUS) |
| { |
| no_cache_dnssec = 1; |
| bogusanswer = 1; |
| } |
| } |
| |
| #endif |
| |
| /* restore CD bit to the value in the query */ |
| if (forward->flags & FREC_CHECKING_DISABLED) |
| header->hb4 |= HB4_CD; |
| else |
| header->hb4 &= ~HB4_CD; |
| |
| if ((nn = process_reply(header, now, forward->sentto, (size_t)n, check_rebind, no_cache_dnssec, cache_secure, bogusanswer, |
| forward->flags & FREC_AD_QUESTION, forward->flags & FREC_DO_QUESTION, |
| forward->flags & FREC_ADDED_PHEADER, forward->flags & FREC_HAS_SUBNET, &forward->source))) |
| { |
| header->id = htons(forward->orig_id); |
| header->hb4 |= HB4_RA; /* recursion if available */ |
| #ifdef HAVE_DNSSEC |
| /* We added an EDNSO header for the purpose of getting DNSSEC RRs, and set the value of the UDP payload size |
| greater than the no-EDNS0-implied 512 to have space for the RRSIGS. If, having stripped them and the EDNS0 |
| header, the answer is still bigger than 512, truncate it and mark it so. The client then retries with TCP. */ |
| if (option_bool(OPT_DNSSEC_VALID) && (forward->flags & FREC_ADDED_PHEADER) && (nn > PACKETSZ)) |
| { |
| header->ancount = htons(0); |
| header->nscount = htons(0); |
| header->arcount = htons(0); |
| header->hb3 |= HB3_TC; |
| nn = resize_packet(header, nn, NULL, 0); |
| } |
| #endif |
| |
| #ifdef HAVE_DUMPFILE |
| dump_packet(DUMP_REPLY, daemon->packet, (size_t)nn, NULL, &forward->source); |
| #endif |
| |
| send_from(forward->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn, |
| &forward->source, &forward->dest, forward->iface); |
| } |
| free_frec(forward); /* cancel */ |
| } |
| } |
| |
| |
| void receive_query(struct listener *listen, time_t now) |
| { |
| struct dns_header *header = (struct dns_header *)daemon->packet; |
| union mysockaddr source_addr; |
| unsigned char *pheader; |
| unsigned short type, udp_size = PACKETSZ; /* default if no EDNS0 */ |
| union all_addr dst_addr; |
| struct in_addr netmask, dst_addr_4; |
| size_t m; |
| ssize_t n; |
| int if_index = 0, auth_dns = 0, do_bit = 0, have_pseudoheader = 0; |
| #ifdef HAVE_AUTH |
| int local_auth = 0; |
| #endif |
| struct iovec iov[1]; |
| struct msghdr msg; |
| struct cmsghdr *cmptr; |
| union { |
| struct cmsghdr align; /* this ensures alignment */ |
| char control6[CMSG_SPACE(sizeof(struct in6_pktinfo))]; |
| #if defined(HAVE_LINUX_NETWORK) |
| char control[CMSG_SPACE(sizeof(struct in_pktinfo))]; |
| #elif defined(IP_RECVDSTADDR) && defined(HAVE_SOLARIS_NETWORK) |
| char control[CMSG_SPACE(sizeof(struct in_addr)) + |
| CMSG_SPACE(sizeof(unsigned int))]; |
| #elif defined(IP_RECVDSTADDR) |
| char control[CMSG_SPACE(sizeof(struct in_addr)) + |
| CMSG_SPACE(sizeof(struct sockaddr_dl))]; |
| #endif |
| } control_u; |
| /* Can always get recvd interface for IPv6 */ |
| int check_dst = !option_bool(OPT_NOWILD) || listen->family == AF_INET6; |
| |
| /* packet buffer overwritten */ |
| daemon->srv_save = NULL; |
| |
| dst_addr_4.s_addr = dst_addr.addr4.s_addr = 0; |
| netmask.s_addr = 0; |
| |
| if (option_bool(OPT_NOWILD) && listen->iface) |
| { |
| auth_dns = listen->iface->dns_auth; |
| |
| if (listen->family == AF_INET) |
| { |
| dst_addr_4 = dst_addr.addr4 = listen->iface->addr.in.sin_addr; |
| netmask = listen->iface->netmask; |
| } |
| } |
| |
| iov[0].iov_base = daemon->packet; |
| iov[0].iov_len = daemon->edns_pktsz; |
| |
| msg.msg_control = control_u.control; |
| msg.msg_controllen = sizeof(control_u); |
| msg.msg_flags = 0; |
| msg.msg_name = &source_addr; |
| msg.msg_namelen = sizeof(source_addr); |
| msg.msg_iov = iov; |
| msg.msg_iovlen = 1; |
| |
| if ((n = recvmsg(listen->fd, &msg, 0)) == -1) |
| return; |
| |
| if (n < (int)sizeof(struct dns_header) || |
| (msg.msg_flags & MSG_TRUNC) || |
| (header->hb3 & HB3_QR)) |
| return; |
| |
| /* Clear buffer beyond request to avoid risk of |
| information disclosure. */ |
| memset(daemon->packet + n, 0, daemon->edns_pktsz - n); |
| |
| source_addr.sa.sa_family = listen->family; |
| |
| if (listen->family == AF_INET) |
| { |
| /* Source-port == 0 is an error, we can't send back to that. |
| http://www.ietf.org/mail-archive/web/dnsop/current/msg11441.html */ |
| if (source_addr.in.sin_port == 0) |
| return; |
| } |
| else |
| { |
| /* Source-port == 0 is an error, we can't send back to that. */ |
| if (source_addr.in6.sin6_port == 0) |
| return; |
| source_addr.in6.sin6_flowinfo = 0; |
| } |
| |
| /* We can be configured to only accept queries from at-most-one-hop-away addresses. */ |
| if (option_bool(OPT_LOCAL_SERVICE)) |
| { |
| struct addrlist *addr; |
| |
| if (listen->family == AF_INET6) |
| { |
| for (addr = daemon->interface_addrs; addr; addr = addr->next) |
| if ((addr->flags & ADDRLIST_IPV6) && |
| is_same_net6(&addr->addr.addr6, &source_addr.in6.sin6_addr, addr->prefixlen)) |
| break; |
| } |
| else |
| { |
| struct in_addr netmask; |
| for (addr = daemon->interface_addrs; addr; addr = addr->next) |
| { |
| netmask.s_addr = htonl(~(in_addr_t)0 << (32 - addr->prefixlen)); |
| if (!(addr->flags & ADDRLIST_IPV6) && |
| is_same_net(addr->addr.addr4, source_addr.in.sin_addr, netmask)) |
| break; |
| } |
| } |
| if (!addr) |
| { |
| static int warned = 0; |
| if (!warned) |
| { |
| my_syslog(LOG_WARNING, _("Ignoring query from non-local network")); |
| warned = 1; |
| } |
| return; |
| } |
| } |
| |
| if (check_dst) |
| { |
| struct ifreq ifr; |
| |
| if (msg.msg_controllen < sizeof(struct cmsghdr)) |
| return; |
| |
| #if defined(HAVE_LINUX_NETWORK) |
| if (listen->family == AF_INET) |
| for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr)) |
| if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_PKTINFO) |
| { |
| union { |
| unsigned char *c; |
| struct in_pktinfo *p; |
| } p; |
| p.c = CMSG_DATA(cmptr); |
| dst_addr_4 = dst_addr.addr4 = p.p->ipi_spec_dst; |
| if_index = p.p->ipi_ifindex; |
| } |
| #elif defined(IP_RECVDSTADDR) && defined(IP_RECVIF) |
| if (listen->family == AF_INET) |
| { |
| for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr)) |
| { |
| union { |
| unsigned char *c; |
| unsigned int *i; |
| struct in_addr *a; |
| #ifndef HAVE_SOLARIS_NETWORK |
| struct sockaddr_dl *s; |
| #endif |
| } p; |
| p.c = CMSG_DATA(cmptr); |
| if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVDSTADDR) |
| dst_addr_4 = dst_addr.addr4 = *(p.a); |
| else if (cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_RECVIF) |
| #ifdef HAVE_SOLARIS_NETWORK |
| if_index = *(p.i); |
| #else |
| if_index = p.s->sdl_index; |
| #endif |
| } |
| } |
| #endif |
| |
| if (listen->family == AF_INET6) |
| { |
| for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr)) |
| if (cmptr->cmsg_level == IPPROTO_IPV6 && cmptr->cmsg_type == daemon->v6pktinfo) |
| { |
| union { |
| unsigned char *c; |
| struct in6_pktinfo *p; |
| } p; |
| p.c = CMSG_DATA(cmptr); |
| |
| dst_addr.addr6 = p.p->ipi6_addr; |
| if_index = p.p->ipi6_ifindex; |
| } |
| } |
| |
| /* enforce available interface configuration */ |
| |
| if (!indextoname(listen->fd, if_index, ifr.ifr_name)) |
| return; |
| |
| if (!iface_check(listen->family, &dst_addr, ifr.ifr_name, &auth_dns)) |
| { |
| if (!option_bool(OPT_CLEVERBIND)) |
| enumerate_interfaces(0); |
| if (!loopback_exception(listen->fd, listen->family, &dst_addr, ifr.ifr_name) && |
| !label_exception(if_index, listen->family, &dst_addr)) |
| return; |
| } |
| |
| if (listen->family == AF_INET && option_bool(OPT_LOCALISE)) |
| { |
| struct irec *iface; |
| |
| /* get the netmask of the interface which has the address we were sent to. |
| This is no necessarily the interface we arrived on. */ |
| |
| for (iface = daemon->interfaces; iface; iface = iface->next) |
| if (iface->addr.sa.sa_family == AF_INET && |
| iface->addr.in.sin_addr.s_addr == dst_addr_4.s_addr) |
| break; |
| |
| /* interface may be new */ |
| if (!iface && !option_bool(OPT_CLEVERBIND)) |
| enumerate_interfaces(0); |
| |
| for (iface = daemon->interfaces; iface; iface = iface->next) |
| if (iface->addr.sa.sa_family == AF_INET && |
| iface->addr.in.sin_addr.s_addr == dst_addr_4.s_addr) |
| break; |
| |
| /* If we failed, abandon localisation */ |
| if (iface) |
| netmask = iface->netmask; |
| else |
| dst_addr_4.s_addr = 0; |
| } |
| } |
| |
| /* log_query gets called indirectly all over the place, so |
| pass these in global variables - sorry. */ |
| daemon->log_display_id = ++daemon->log_id; |
| daemon->log_source_addr = &source_addr; |
| |
| #ifdef HAVE_DUMPFILE |
| dump_packet(DUMP_QUERY, daemon->packet, (size_t)n, &source_addr, NULL); |
| #endif |
| |
| if (extract_request(header, (size_t)n, daemon->namebuff, &type)) |
| { |
| #ifdef HAVE_AUTH |
| struct auth_zone *zone; |
| #endif |
| char *types = querystr(auth_dns ? "auth" : "query", type); |
| |
| if (listen->family == AF_INET) |
| log_query(F_QUERY | F_IPV4 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&source_addr.in.sin_addr, types); |
| else |
| log_query(F_QUERY | F_IPV6 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&source_addr.in6.sin6_addr, types); |
| |
| #ifdef HAVE_AUTH |
| /* find queries for zones we're authoritative for, and answer them directly */ |
| if (!auth_dns && !option_bool(OPT_LOCALISE)) |
| for (zone = daemon->auth_zones; zone; zone = zone->next) |
| if (in_zone(zone, daemon->namebuff, NULL)) |
| { |
| auth_dns = 1; |
| local_auth = 1; |
| break; |
| } |
| #endif |
| |
| #ifdef HAVE_LOOP |
| /* Check for forwarding loop */ |
| if (detect_loop(daemon->namebuff, type)) |
| return; |
| #endif |
| } |
| |
| if (find_pseudoheader(header, (size_t)n, NULL, &pheader, NULL, NULL)) |
| { |
| unsigned short flags; |
| |
| have_pseudoheader = 1; |
| GETSHORT(udp_size, pheader); |
| pheader += 2; /* ext_rcode */ |
| GETSHORT(flags, pheader); |
| |
| if (flags & 0x8000) |
| do_bit = 1;/* do bit */ |
| |
| /* If the client provides an EDNS0 UDP size, use that to limit our reply. |
| (bounded by the maximum configured). If no EDNS0, then it |
| defaults to 512 */ |
| if (udp_size > daemon->edns_pktsz) |
| udp_size = daemon->edns_pktsz; |
| else if (udp_size < PACKETSZ) |
| udp_size = PACKETSZ; /* Sanity check - can't reduce below default. RFC 6891 6.2.3 */ |
| } |
| |
| #ifdef HAVE_AUTH |
| if (auth_dns) |
| { |
| m = answer_auth(header, ((char *) header) + udp_size, (size_t)n, now, &source_addr, |
| local_auth, do_bit, have_pseudoheader); |
| if (m >= 1) |
| { |
| send_from(listen->fd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), |
| (char *)header, m, &source_addr, &dst_addr, if_index); |
| daemon->metrics[METRIC_DNS_AUTH_ANSWERED]++; |
| } |
| } |
| else |
| #endif |
| { |
| int ad_reqd = do_bit; |
| /* RFC 6840 5.7 */ |
| if (header->hb4 & HB4_AD) |
| ad_reqd = 1; |
| |
| m = answer_request(header, ((char *) header) + udp_size, (size_t)n, |
| dst_addr_4, netmask, now, ad_reqd, do_bit, have_pseudoheader); |
| |
| if (m >= 1) |
| { |
| send_from(listen->fd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), |
| (char *)header, m, &source_addr, &dst_addr, if_index); |
| daemon->metrics[METRIC_DNS_LOCAL_ANSWERED]++; |
| } |
| else if (forward_query(listen->fd, &source_addr, &dst_addr, if_index, |
| header, (size_t)n, now, NULL, ad_reqd, do_bit)) |
| daemon->metrics[METRIC_DNS_QUERIES_FORWARDED]++; |
| else |
| daemon->metrics[METRIC_DNS_LOCAL_ANSWERED]++; |
| } |
| } |
| |
| #ifdef HAVE_DNSSEC |
| /* Recurse up the key hierarchy */ |
| static int tcp_key_recurse(time_t now, int status, struct dns_header *header, size_t n, |
| int class, char *name, char *keyname, struct server *server, |
| int have_mark, unsigned int mark, int *keycount) |
| { |
| int new_status; |
| unsigned char *packet = NULL; |
| unsigned char *payload = NULL; |
| struct dns_header *new_header = NULL; |
| u16 *length = NULL; |
| |
| while (1) |
| { |
| int type = SERV_DO_DNSSEC; |
| char *domain; |
| size_t m; |
| unsigned char c1, c2; |
| struct server *firstsendto = NULL; |
| |
| /* limit the amount of work we do, to avoid cycling forever on loops in the DNS */ |
| if (--(*keycount) == 0) |
| new_status = STAT_ABANDONED; |
| else if (status == STAT_NEED_KEY) |
| new_status = dnssec_validate_by_ds(now, header, n, name, keyname, class); |
| else if (status == STAT_NEED_DS) |
| new_status = dnssec_validate_ds(now, header, n, name, keyname, class); |
| else |
| new_status = dnssec_validate_reply(now, header, n, name, keyname, &class, |
| !option_bool(OPT_DNSSEC_IGN_NS) && (server->flags & SERV_DO_DNSSEC), |
| NULL, NULL, NULL); |
| |
| if (new_status != STAT_NEED_DS && new_status != STAT_NEED_KEY) |
| break; |
| |
| /* Can't validate because we need a key/DS whose name now in keyname. |
| Make query for same, and recurse to validate */ |
| if (!packet) |
| { |
| packet = whine_malloc(65536 + MAXDNAME + RRFIXEDSZ + sizeof(u16)); |
| payload = &packet[2]; |
| new_header = (struct dns_header *)payload; |
| length = (u16 *)packet; |
| } |
| |
| if (!packet) |
| { |
| new_status = STAT_ABANDONED; |
| break; |
| } |
| |
| m = dnssec_generate_query(new_header, ((unsigned char *) new_header) + 65536, keyname, class, |
| new_status == STAT_NEED_KEY ? T_DNSKEY : T_DS, server->edns_pktsz); |
| |
| *length = htons(m); |
| |
| /* Find server to forward to. This will normally be the |
| same as for the original query, but may be another if |
| servers for domains are involved. */ |
| if (search_servers(now, NULL, F_DNSSECOK, keyname, &type, &domain, NULL) != 0) |
| { |
| new_status = STAT_ABANDONED; |
| break; |
| } |
| |
| while (1) |
| { |
| int data_sent = 0; |
| |
| if (!firstsendto) |
| firstsendto = server; |
| else |
| { |
| if (!(server = server->next)) |
| server = daemon->servers; |
| if (server == firstsendto) |
| { |
| /* can't find server to accept our query. */ |
| new_status = STAT_ABANDONED; |
| break; |
| } |
| } |
| |
| if (type != (server->flags & (SERV_TYPE | SERV_DO_DNSSEC)) || |
| (type == SERV_HAS_DOMAIN && !hostname_isequal(domain, server->domain)) || |
| (server->flags & (SERV_LITERAL_ADDRESS | SERV_LOOP))) |
| continue; |
| |
| retry: |
| /* may need to make new connection. */ |
| if (server->tcpfd == -1) |
| { |
| if ((server->tcpfd = socket(server->addr.sa.sa_family, SOCK_STREAM, 0)) == -1) |
| continue; /* No good, next server */ |
| |
| #ifdef HAVE_CONNTRACK |
| /* Copy connection mark of incoming query to outgoing connection. */ |
| if (have_mark) |
| setsockopt(server->tcpfd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int)); |
| #endif |
| |
| if (!local_bind(server->tcpfd, &server->source_addr, server->interface, 0, 1)) |
| { |
| close(server->tcpfd); |
| server->tcpfd = -1; |
| continue; /* No good, next server */ |
| } |
| |
| #ifdef MSG_FASTOPEN |
| while(retry_send(sendto(server->tcpfd, packet, m + sizeof(u16), |
| MSG_FASTOPEN, &server->addr.sa, sa_len(&server->addr)))); |
| |
| if (errno == 0) |
| data_sent = 1; |
| #endif |
| |
| if (!data_sent && connect(server->tcpfd, &server->addr.sa, sa_len(&server->addr)) == -1) |
| { |
| close(server->tcpfd); |
| server->tcpfd = -1; |
| continue; /* No good, next server */ |
| } |
| |
| server->flags &= ~SERV_GOT_TCP; |
| } |
| |
| if ((!data_sent && !read_write(server->tcpfd, packet, m + sizeof(u16), 0)) || |
| !read_write(server->tcpfd, &c1, 1, 1) || |
| !read_write(server->tcpfd, &c2, 1, 1) || |
| !read_write(server->tcpfd, payload, (c1 << 8) | c2, 1)) |
| { |
| close(server->tcpfd); |
| server->tcpfd = -1; |
| /* We get data then EOF, reopen connection to same server, |
| else try next. This avoids DoS from a server which accepts |
| connections and then closes them. */ |
| if (server->flags & SERV_GOT_TCP) |
| goto retry; |
| else |
| continue; |
| } |
| |
| |
| if (server->addr.sa.sa_family == AF_INET) |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV4, keyname, (union all_addr *)&(server->addr.in.sin_addr), |
| querystr("dnssec-query", new_status == STAT_NEED_KEY ? T_DNSKEY : T_DS)); |
| else |
| log_query(F_NOEXTRA | F_DNSSEC | F_IPV6, keyname, (union all_addr *)&(server->addr.in6.sin6_addr), |
| querystr("dnssec-query", new_status == STAT_NEED_KEY ? T_DNSKEY : T_DS)); |
| |
| server->flags |= SERV_GOT_TCP; |
| |
| m = (c1 << 8) | c2; |
| new_status = tcp_key_recurse(now, new_status, new_header, m, class, name, keyname, server, have_mark, mark, keycount); |
| break; |
| } |
| |
| if (new_status != STAT_OK) |
| break; |
| } |
| |
| if (packet) |
| free(packet); |
| |
| return new_status; |
| } |
| #endif |
| |
| |
| /* The daemon forks before calling this: it should deal with one connection, |
| blocking as necessary, and then return. Note, need to be a bit careful |
| about resources for debug mode, when the fork is suppressed: that's |
| done by the caller. */ |
| unsigned char *tcp_request(int confd, time_t now, |
| union mysockaddr *local_addr, struct in_addr netmask, int auth_dns) |
| { |
| size_t size = 0; |
| int norebind = 0; |
| #ifdef HAVE_AUTH |
| int local_auth = 0; |
| #endif |
| int checking_disabled, do_bit, added_pheader = 0, have_pseudoheader = 0; |
| int check_subnet, no_cache_dnssec = 0, cache_secure = 0, bogusanswer = 0; |
| size_t m; |
| unsigned short qtype; |
| unsigned int gotname; |
| unsigned char c1, c2; |
| /* Max TCP packet + slop + size */ |
| unsigned char *packet = whine_malloc(65536 + MAXDNAME + RRFIXEDSZ + sizeof(u16)); |
| unsigned char *payload = &packet[2]; |
| /* largest field in header is 16-bits, so this is still sufficiently aligned */ |
| struct dns_header *header = (struct dns_header *)payload; |
| u16 *length = (u16 *)packet; |
| struct server *last_server; |
| struct in_addr dst_addr_4; |
| union mysockaddr peer_addr; |
| socklen_t peer_len = sizeof(union mysockaddr); |
| int query_count = 0; |
| unsigned char *pheader; |
| unsigned int mark = 0; |
| int have_mark = 0; |
| |
| (void)mark; |
| (void)have_mark; |
| |
| if (getpeername(confd, (struct sockaddr *)&peer_addr, &peer_len) == -1) |
| return packet; |
| |
| #ifdef HAVE_CONNTRACK |
| /* Get connection mark of incoming query to set on outgoing connections. */ |
| if (option_bool(OPT_CONNTRACK)) |
| { |
| union all_addr local; |
| |
| if (local_addr->sa.sa_family == AF_INET6) |
| local.addr6 = local_addr->in6.sin6_addr; |
| else |
| local.addr4 = local_addr->in.sin_addr; |
| |
| have_mark = get_incoming_mark(&peer_addr, &local, 1, &mark); |
| } |
| #endif |
| |
| /* We can be configured to only accept queries from at-most-one-hop-away addresses. */ |
| if (option_bool(OPT_LOCAL_SERVICE)) |
| { |
| struct addrlist *addr; |
| |
| if (peer_addr.sa.sa_family == AF_INET6) |
| { |
| for (addr = daemon->interface_addrs; addr; addr = addr->next) |
| if ((addr->flags & ADDRLIST_IPV6) && |
| is_same_net6(&addr->addr.addr6, &peer_addr.in6.sin6_addr, addr->prefixlen)) |
| break; |
| } |
| else |
| { |
| struct in_addr netmask; |
| for (addr = daemon->interface_addrs; addr; addr = addr->next) |
| { |
| netmask.s_addr = htonl(~(in_addr_t)0 << (32 - addr->prefixlen)); |
| if (!(addr->flags & ADDRLIST_IPV6) && |
| is_same_net(addr->addr.addr4, peer_addr.in.sin_addr, netmask)) |
| break; |
| } |
| } |
| if (!addr) |
| { |
| my_syslog(LOG_WARNING, _("Ignoring query from non-local network")); |
| return packet; |
| } |
| } |
| |
| while (1) |
| { |
| if (query_count == TCP_MAX_QUERIES || |
| !packet || |
| !read_write(confd, &c1, 1, 1) || !read_write(confd, &c2, 1, 1) || |
| !(size = c1 << 8 | c2) || |
| !read_write(confd, payload, size, 1)) |
| return packet; |
| |
| if (size < (int)sizeof(struct dns_header)) |
| continue; |
| |
| /* Clear buffer beyond request to avoid risk of |
| information disclosure. */ |
| memset(payload + size, 0, 65536 - size); |
| |
| query_count++; |
| |
| /* log_query gets called indirectly all over the place, so |
| pass these in global variables - sorry. */ |
| daemon->log_display_id = ++daemon->log_id; |
| daemon->log_source_addr = &peer_addr; |
| |
| /* save state of "cd" flag in query */ |
| if ((checking_disabled = header->hb4 & HB4_CD)) |
| no_cache_dnssec = 1; |
| |
| if ((gotname = extract_request(header, (unsigned int)size, daemon->namebuff, &qtype))) |
| { |
| #ifdef HAVE_AUTH |
| struct auth_zone *zone; |
| #endif |
| char *types = querystr(auth_dns ? "auth" : "query", qtype); |
| |
| if (peer_addr.sa.sa_family == AF_INET) |
| log_query(F_QUERY | F_IPV4 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&peer_addr.in.sin_addr, types); |
| else |
| log_query(F_QUERY | F_IPV6 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&peer_addr.in6.sin6_addr, types); |
| |
| #ifdef HAVE_AUTH |
| /* find queries for zones we're authoritative for, and answer them directly */ |
| if (!auth_dns && !option_bool(OPT_LOCALISE)) |
| for (zone = daemon->auth_zones; zone; zone = zone->next) |
| if (in_zone(zone, daemon->namebuff, NULL)) |
| { |
| auth_dns = 1; |
| local_auth = 1; |
| break; |
| } |
| #endif |
| } |
| |
| if (local_addr->sa.sa_family == AF_INET) |
| dst_addr_4 = local_addr->in.sin_addr; |
| else |
| dst_addr_4.s_addr = 0; |
| |
| do_bit = 0; |
| |
| if (find_pseudoheader(header, (size_t)size, NULL, &pheader, NULL, NULL)) |
| { |
| unsigned short flags; |
| |
| have_pseudoheader = 1; |
| pheader += 4; /* udp_size, ext_rcode */ |
| GETSHORT(flags, pheader); |
| |
| if (flags & 0x8000) |
| do_bit = 1; /* do bit */ |
| } |
| |
| #ifdef HAVE_AUTH |
| if (auth_dns) |
| m = answer_auth(header, ((char *) header) + 65536, (size_t)size, now, &peer_addr, |
| local_auth, do_bit, have_pseudoheader); |
| else |
| #endif |
| { |
| int ad_reqd = do_bit; |
| /* RFC 6840 5.7 */ |
| if (header->hb4 & HB4_AD) |
| ad_reqd = 1; |
| |
| /* m > 0 if answered from cache */ |
| m = answer_request(header, ((char *) header) + 65536, (size_t)size, |
| dst_addr_4, netmask, now, ad_reqd, do_bit, have_pseudoheader); |
| |
| /* Do this by steam now we're not in the select() loop */ |
| check_log_writer(1); |
| |
| if (m == 0) |
| { |
| unsigned int flags = 0; |
| union all_addr *addrp = NULL; |
| int type = SERV_DO_DNSSEC; |
| char *domain = NULL; |
| unsigned char *oph = find_pseudoheader(header, size, NULL, NULL, NULL, NULL); |
| |
| size = add_edns0_config(header, size, ((unsigned char *) header) + 65536, &peer_addr, now, &check_subnet); |
| |
| if (gotname) |
| flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind); |
| |
| #ifdef HAVE_DNSSEC |
| if (option_bool(OPT_DNSSEC_VALID) && (type & SERV_DO_DNSSEC)) |
| { |
| size = add_do_bit(header, size, ((unsigned char *) header) + 65536); |
| |
| /* For debugging, set Checking Disabled, otherwise, have the upstream check too, |
| this allows it to select auth servers when one is returning bad data. */ |
| if (option_bool(OPT_DNSSEC_DEBUG)) |
| header->hb4 |= HB4_CD; |
| } |
| #endif |
| |
| /* Check if we added a pheader on forwarding - may need to |
| strip it from the reply. */ |
| if (!oph && find_pseudoheader(header, size, NULL, NULL, NULL, NULL)) |
| added_pheader = 1; |
| |
| type &= ~SERV_DO_DNSSEC; |
| |
| if (type != 0 || option_bool(OPT_ORDER) || !daemon->last_server) |
| last_server = daemon->servers; |
| else |
| last_server = daemon->last_server; |
| |
| if (!flags && last_server) |
| { |
| struct server *firstsendto = NULL; |
| #ifdef HAVE_DNSSEC |
| unsigned char *newhash, hash[HASH_SIZE]; |
| if ((newhash = hash_questions(header, (unsigned int)size, daemon->namebuff))) |
| memcpy(hash, newhash, HASH_SIZE); |
| else |
| memset(hash, 0, HASH_SIZE); |
| #else |
| unsigned int crc = questions_crc(header, (unsigned int)size, daemon->namebuff); |
| #endif |
| /* Loop round available servers until we succeed in connecting to one. |
| Note that this code subtly ensures that consecutive queries on this connection |
| which can go to the same server, do so. */ |
| while (1) |
| { |
| int data_sent = 0; |
| |
| if (!firstsendto) |
| firstsendto = last_server; |
| else |
| { |
| if (!(last_server = last_server->next)) |
| last_server = daemon->servers; |
| |
| if (last_server == firstsendto) |
| break; |
| } |
| |
| /* server for wrong domain */ |
| if (type != (last_server->flags & SERV_TYPE) || |
| (type == SERV_HAS_DOMAIN && !hostname_isequal(domain, last_server->domain)) || |
| (last_server->flags & (SERV_LITERAL_ADDRESS | SERV_LOOP))) |
| continue; |
| |
| retry: |
| *length = htons(size); |
| |
| if (last_server->tcpfd == -1) |
| { |
| if ((last_server->tcpfd = socket(last_server->addr.sa.sa_family, SOCK_STREAM, 0)) == -1) |
| continue; |
| |
| #ifdef HAVE_CONNTRACK |
| /* Copy connection mark of incoming query to outgoing connection. */ |
| if (have_mark) |
| setsockopt(last_server->tcpfd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int)); |
| #endif |
| |
| if ((!local_bind(last_server->tcpfd, &last_server->source_addr, last_server->interface, 0, 1))) |
| { |
| close(last_server->tcpfd); |
| last_server->tcpfd = -1; |
| continue; |
| } |
| |
| #ifdef MSG_FASTOPEN |
| while(retry_send(sendto(last_server->tcpfd, packet, size + sizeof(u16), |
| MSG_FASTOPEN, &last_server->addr.sa, sa_len(&last_server->addr)))); |
| |
| if (errno == 0) |
| data_sent = 1; |
| #endif |
| |
| if (!data_sent && connect(last_server->tcpfd, &last_server->addr.sa, sa_len(&last_server->addr)) == -1) |
| { |
| close(last_server->tcpfd); |
| last_server->tcpfd = -1; |
| continue; |
| } |
| |
| last_server->flags &= ~SERV_GOT_TCP; |
| } |
| |
| /* get query name again for logging - may have been overwritten */ |
| if (!(gotname = extract_request(header, (unsigned int)size, daemon->namebuff, &qtype))) |
| strcpy(daemon->namebuff, "query"); |
| |
| if ((!data_sent && !read_write(last_server->tcpfd, packet, size + sizeof(u16), 0)) || |
| !read_write(last_server->tcpfd, &c1, 1, 1) || |
| !read_write(last_server->tcpfd, &c2, 1, 1) || |
| !read_write(last_server->tcpfd, payload, (c1 << 8) | c2, 1)) |
| { |
| close(last_server->tcpfd); |
| last_server->tcpfd = -1; |
| /* We get data then EOF, reopen connection to same server, |
| else try next. This avoids DoS from a server which accepts |
| connections and then closes them. */ |
| if (last_server->flags & SERV_GOT_TCP) |
| goto retry; |
| else |
| continue; |
| } |
| |
| last_server->flags |= SERV_GOT_TCP; |
| |
| m = (c1 << 8) | c2; |
| |
| if (last_server->addr.sa.sa_family == AF_INET) |
| log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&last_server->addr.in.sin_addr, NULL); |
| else |
| log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff, |
| (union all_addr *)&last_server->addr.in6.sin6_addr, NULL); |
| |
| #ifdef HAVE_DNSSEC |
| if (option_bool(OPT_DNSSEC_VALID) && !checking_disabled && (last_server->flags & SERV_DO_DNSSEC)) |
| { |
| int keycount = DNSSEC_WORK; /* Limit to number of DNSSEC questions, to catch loops and avoid filling cache. */ |
| int status = tcp_key_recurse(now, STAT_OK, header, m, 0, daemon->namebuff, daemon->keyname, |
| last_server, have_mark, mark, &keycount); |
| char *result, *domain = "result"; |
| |
| if (status == STAT_ABANDONED) |
| { |
| result = "ABANDONED"; |
| status = STAT_BOGUS; |
| } |
| else |
| result = (status == STAT_SECURE ? "SECURE" : (status == STAT_INSECURE ? "INSECURE" : "BOGUS")); |
| |
| if (status == STAT_BOGUS && extract_request(header, m, daemon->namebuff, NULL)) |
| domain = daemon->namebuff; |
| |
| log_query(F_SECSTAT, domain, NULL, result); |
| |
| if (status == STAT_BOGUS) |
| { |
| no_cache_dnssec = 1; |
| bogusanswer = 1; |
| } |
| |
| if (status == STAT_SECURE) |
| cache_secure = 1; |
| } |
| #endif |
| |
| /* restore CD bit to the value in the query */ |
| if (checking_disabled) |
| header->hb4 |= HB4_CD; |
| else |
| header->hb4 &= ~HB4_CD; |
| |
| /* There's no point in updating the cache, since this process will exit and |
| lose the information after a few queries. We make this call for the alias and |
| bogus-nxdomain side-effects. */ |
| /* If the crc of the question section doesn't match the crc we sent, then |
| someone might be attempting to insert bogus values into the cache by |
| sending replies containing questions and bogus answers. */ |
| #ifdef HAVE_DNSSEC |
| newhash = hash_questions(header, (unsigned int)m, daemon->namebuff); |
| if (!newhash || memcmp(hash, newhash, HASH_SIZE) != 0) |
| { |
| m = 0; |
| break; |
| } |
| #else |
| if (crc != questions_crc(header, (unsigned int)m, daemon->namebuff)) |
| { |
| m = 0; |
| break; |
| } |
| #endif |
| |
| m = process_reply(header, now, last_server, (unsigned int)m, |
| option_bool(OPT_NO_REBIND) && !norebind, no_cache_dnssec, cache_secure, bogusanswer, |
| ad_reqd, do_bit, added_pheader, check_subnet, &peer_addr); |
| |
| break; |
| } |
| } |
| |
| /* In case of local answer or no connections made. */ |
| if (m == 0) |
| { |
| m = setup_reply(header, (unsigned int)size, addrp, flags, daemon->local_ttl); |
| if (have_pseudoheader) |
| m = add_pseudoheader(header, m, ((unsigned char *) header) + 65536, daemon->edns_pktsz, 0, NULL, 0, do_bit, 0); |
| } |
| } |
| } |
| |
| check_log_writer(1); |
| |
| *length = htons(m); |
| |
| if (m == 0 || !read_write(confd, packet, m + sizeof(u16), 0)) |
| return packet; |
| } |
| } |
| |
| static struct frec *allocate_frec(time_t now) |
| { |
| struct frec *f; |
| |
| if ((f = (struct frec *)whine_malloc(sizeof(struct frec)))) |
| { |
| f->next = daemon->frec_list; |
| f->time = now; |
| f->sentto = NULL; |
| f->rfd4 = NULL; |
| f->flags = 0; |
| f->rfd6 = NULL; |
| #ifdef HAVE_DNSSEC |
| f->dependent = NULL; |
| f->blocking_query = NULL; |
| f->stash = NULL; |
| #endif |
| daemon->frec_list = f; |
| } |
| |
| return f; |
| } |
| |
| struct randfd *allocate_rfd(int family) |
| { |
| static int finger = 0; |
| int i; |
| |
| /* limit the number of sockets we have open to avoid starvation of |
| (eg) TFTP. Once we have a reasonable number, randomness should be OK */ |
| |
| for (i = 0; i < RANDOM_SOCKS; i++) |
| if (daemon->randomsocks[i].refcount == 0) |
| { |
| if ((daemon->randomsocks[i].fd = random_sock(family)) == -1) |
| break; |
| |
| daemon->randomsocks[i].refcount = 1; |
| daemon->randomsocks[i].family = family; |
| return &daemon->randomsocks[i]; |
| } |
| |
| /* No free ones or cannot get new socket, grab an existing one */ |
| for (i = 0; i < RANDOM_SOCKS; i++) |
| { |
| int j = (i+finger) % RANDOM_SOCKS; |
| if (daemon->randomsocks[j].refcount != 0 && |
| daemon->randomsocks[j].family == family && |
| daemon->randomsocks[j].refcount != 0xffff) |
| { |
| finger = j; |
| daemon->randomsocks[j].refcount++; |
| return &daemon->randomsocks[j]; |
| } |
| } |
| |
| return NULL; /* doom */ |
| } |
| |
| void free_rfd(struct randfd *rfd) |
| { |
| if (rfd && --(rfd->refcount) == 0) |
| close(rfd->fd); |
| } |
| |
| static void free_frec(struct frec *f) |
| { |
| free_rfd(f->rfd4); |
| f->rfd4 = NULL; |
| f->sentto = NULL; |
| f->flags = 0; |
| free_rfd(f->rfd6); |
| f->rfd6 = NULL; |
| |
| #ifdef HAVE_DNSSEC |
| if (f->stash) |
| { |
| blockdata_free(f->stash); |
| f->stash = NULL; |
| } |
| |
| /* Anything we're waiting on is pointless now, too */ |
| if (f->blocking_query) |
| free_frec(f->blocking_query); |
| f->blocking_query = NULL; |
| f->dependent = NULL; |
| #endif |
| } |
| |
| |
| |
| /* if wait==NULL return a free or older than TIMEOUT record. |
| else return *wait zero if one available, or *wait is delay to |
| when the oldest in-use record will expire. Impose an absolute |
| limit of 4*TIMEOUT before we wipe things (for random sockets). |
| If force is set, always return a result, even if we have |
| to allocate above the limit. */ |
| struct frec *get_new_frec(time_t now, int *wait, int force) |
| { |
| struct frec *f, *oldest, *target; |
| int count; |
| |
| if (wait) |
| *wait = 0; |
| |
| for (f = daemon->frec_list, oldest = NULL, target = NULL, count = 0; f; f = f->next, count++) |
| if (!f->sentto) |
| target = f; |
| else |
| { |
| #ifdef HAVE_DNSSEC |
| /* Don't free DNSSEC sub-queries here, as we may end up with |
| dangling references to them. They'll go when their "real" query |
| is freed. */ |
| if (!f->dependent) |
| #endif |
| { |
| if (difftime(now, f->time) >= 4*TIMEOUT) |
| { |
| free_frec(f); |
| target = f; |
| } |
| |
| |
| if (!oldest || difftime(f->time, oldest->time) <= 0) |
| oldest = f; |
| } |
| } |
| |
| if (target) |
| { |
| target->time = now; |
| return target; |
| } |
| |
| /* can't find empty one, use oldest if there is one |
| and it's older than timeout */ |
| if (!force && oldest && ((int)difftime(now, oldest->time)) >= TIMEOUT) |
| { |
| /* keep stuff for twice timeout if we can by allocating a new |
| record instead */ |
| if (difftime(now, oldest->time) < 2*TIMEOUT && |
| count <= daemon->ftabsize && |
| (f = allocate_frec(now))) |
| return f; |
| |
| if (!wait) |
| { |
| free_frec(oldest); |
| oldest->time = now; |
| } |
| return oldest; |
| } |
| |
| /* none available, calculate time 'till oldest record expires */ |
| if (!force && count > daemon->ftabsize) |
| { |
| static time_t last_log = 0; |
| |
| if (oldest && wait) |
| *wait = oldest->time + (time_t)TIMEOUT - now; |
| |
| if ((int)difftime(now, last_log) > 5) |
| { |
| last_log = now; |
| my_syslog(LOG_WARNING, _("Maximum number of concurrent DNS queries reached (max: %d)"), daemon->ftabsize); |
| } |
| |
| return NULL; |
| } |
| |
| if (!(f = allocate_frec(now)) && wait) |
| /* wait one second on malloc failure */ |
| *wait = 1; |
| |
| return f; /* OK if malloc fails and this is NULL */ |
| } |
| |
| /* crc is all-ones if not known. */ |
| static struct frec *lookup_frec(unsigned short id, void *hash) |
| { |
| struct frec *f; |
| |
| for(f = daemon->frec_list; f; f = f->next) |
| if (f->sentto && f->new_id == id && |
| (!hash || memcmp(hash, f->hash, HASH_SIZE) == 0)) |
| return f; |
| |
| return NULL; |
| } |
| |
| static struct frec *lookup_frec_by_sender(unsigned short id, |
| union mysockaddr *addr, |
| void *hash) |
| { |
| struct frec *f; |
| |
| for(f = daemon->frec_list; f; f = f->next) |
| if (f->sentto && |
| f->orig_id == id && |
| memcmp(hash, f->hash, HASH_SIZE) == 0 && |
| sockaddr_isequal(&f->source, addr)) |
| return f; |
| |
| return NULL; |
| } |
| |
| /* Send query packet again, if we can. */ |
| void resend_query() |
| { |
| if (daemon->srv_save) |
| { |
| int fd; |
| |
| if (daemon->srv_save->sfd) |
| fd = daemon->srv_save->sfd->fd; |
| else if (daemon->rfd_save && daemon->rfd_save->refcount != 0) |
| fd = daemon->rfd_save->fd; |
| else |
| return; |
| |
| while(retry_send(sendto(fd, daemon->packet, daemon->packet_len, 0, |
| &daemon->srv_save->addr.sa, |
| sa_len(&daemon->srv_save->addr)))); |
| } |
| } |
| |
| /* A server record is going away, remove references to it */ |
| void server_gone(struct server *server) |
| { |
| struct frec *f; |
| |
| for (f = daemon->frec_list; f; f = f->next) |
| if (f->sentto && f->sentto == server) |
| free_frec(f); |
| |
| if (daemon->last_server == server) |
| daemon->last_server = NULL; |
| |
| if (daemon->srv_save == server) |
| daemon->srv_save = NULL; |
| } |
| |
| /* return unique random ids. */ |
| static unsigned short get_id(void) |
| { |
| unsigned short ret = 0; |
| |
| do |
| ret = rand16(); |
| while (lookup_frec(ret, NULL)); |
| |
| return ret; |
| } |
| |
| |
| |
| |
| |