| /* dnsmasq is Copyright (c) 2000-2012 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 int add_resource_record(struct dns_header *header, char *limit, int *truncp, |
| unsigned int nameoffset, unsigned char **pp, |
| unsigned long ttl, unsigned int *offset, unsigned short type, |
| unsigned short class, char *format, ...); |
| |
| #define CHECK_LEN(header, pp, plen, len) \ |
| ((size_t)((pp) - (unsigned char *)(header) + (len)) <= (plen)) |
| |
| #define ADD_RDLEN(header, pp, plen, len) \ |
| (!CHECK_LEN(header, pp, plen, len) ? 0 : (long)((pp) += (len)), 1) |
| |
| static int extract_name(struct dns_header *header, size_t plen, unsigned char **pp, |
| char *name, int isExtract, int extrabytes) |
| { |
| unsigned char *cp = (unsigned char *)name, *p = *pp, *p1 = NULL; |
| unsigned int j, l, hops = 0; |
| int retvalue = 1; |
| |
| if (isExtract) |
| *cp = 0; |
| |
| while (1) |
| { |
| unsigned int label_type; |
| |
| if (!CHECK_LEN(header, p, plen, 1)) |
| return 0; |
| |
| if ((l = *p++) == 0) |
| /* end marker */ |
| { |
| /* check that there are the correct no of bytes after the name */ |
| if (!CHECK_LEN(header, p, plen, extrabytes)) |
| return 0; |
| |
| if (isExtract) |
| { |
| if (cp != (unsigned char *)name) |
| cp--; |
| *cp = 0; /* terminate: lose final period */ |
| } |
| else if (*cp != 0) |
| retvalue = 2; |
| |
| if (p1) /* we jumped via compression */ |
| *pp = p1; |
| else |
| *pp = p; |
| |
| return retvalue; |
| } |
| |
| label_type = l & 0xc0; |
| |
| if (label_type == 0xc0) /* pointer */ |
| { |
| if (!CHECK_LEN(header, p, plen, 1)) |
| return 0; |
| |
| /* get offset */ |
| l = (l&0x3f) << 8; |
| l |= *p++; |
| |
| if (!p1) /* first jump, save location to go back to */ |
| p1 = p; |
| |
| hops++; /* break malicious infinite loops */ |
| if (hops > 255) |
| return 0; |
| |
| p = l + (unsigned char *)header; |
| } |
| else if (label_type == 0x80) |
| return 0; /* reserved */ |
| else if (label_type == 0x40) |
| { /* ELT */ |
| unsigned int count, digs; |
| |
| if ((l & 0x3f) != 1) |
| return 0; /* we only understand bitstrings */ |
| |
| if (!isExtract) |
| return 0; /* Cannot compare bitsrings */ |
| |
| count = *p++; |
| if (count == 0) |
| count = 256; |
| digs = ((count-1)>>2)+1; |
| |
| /* output is \[x<hex>/siz]. which is digs+9 chars */ |
| if (cp - (unsigned char *)name + digs + 9 >= MAXDNAME) |
| return 0; |
| if (!CHECK_LEN(header, p, plen, (count-1)>>3)) |
| return 0; |
| |
| *cp++ = '\\'; |
| *cp++ = '['; |
| *cp++ = 'x'; |
| for (j=0; j<digs; j++) |
| { |
| unsigned int dig; |
| if (j%2 == 0) |
| dig = *p >> 4; |
| else |
| dig = *p++ & 0x0f; |
| |
| *cp++ = dig < 10 ? dig + '0' : dig + 'A' - 10; |
| } |
| cp += sprintf((char *)cp, "/%d]", count); |
| /* do this here to overwrite the zero char from sprintf */ |
| *cp++ = '.'; |
| } |
| else |
| { /* label_type = 0 -> label. */ |
| if (cp - (unsigned char *)name + l + 1 >= MAXDNAME) |
| return 0; |
| if (!CHECK_LEN(header, p, plen, l)) |
| return 0; |
| |
| for(j=0; j<l; j++, p++) |
| if (isExtract) |
| { |
| unsigned char c = *p; |
| if (isascii(c) && !iscntrl(c) && c != '.') |
| *cp++ = *p; |
| else |
| return 0; |
| } |
| else |
| { |
| unsigned char c1 = *cp, c2 = *p; |
| |
| if (c1 == 0) |
| retvalue = 2; |
| else |
| { |
| cp++; |
| if (c1 >= 'A' && c1 <= 'Z') |
| c1 += 'a' - 'A'; |
| if (c2 >= 'A' && c2 <= 'Z') |
| c2 += 'a' - 'A'; |
| |
| if (c1 != c2) |
| retvalue = 2; |
| } |
| } |
| |
| if (isExtract) |
| *cp++ = '.'; |
| else if (*cp != 0 && *cp++ != '.') |
| retvalue = 2; |
| } |
| } |
| } |
| |
| /* Max size of input string (for IPv6) is 75 chars.) */ |
| #define MAXARPANAME 75 |
| static int in_arpa_name_2_addr(char *namein, struct all_addr *addrp) |
| { |
| int j; |
| char name[MAXARPANAME+1], *cp1; |
| unsigned char *addr = (unsigned char *)addrp; |
| char *lastchunk = NULL, *penchunk = NULL; |
| |
| if (strlen(namein) > MAXARPANAME) |
| return 0; |
| |
| memset(addrp, 0, sizeof(struct all_addr)); |
| |
| /* turn name into a series of asciiz strings */ |
| /* j counts no of labels */ |
| for(j = 1,cp1 = name; *namein; cp1++, namein++) |
| if (*namein == '.') |
| { |
| penchunk = lastchunk; |
| lastchunk = cp1 + 1; |
| *cp1 = 0; |
| j++; |
| } |
| else |
| *cp1 = *namein; |
| |
| *cp1 = 0; |
| |
| if (j<3) |
| return 0; |
| |
| if (hostname_isequal(lastchunk, "arpa") && hostname_isequal(penchunk, "in-addr")) |
| { |
| /* IP v4 */ |
| /* address arives as a name of the form |
| www.xxx.yyy.zzz.in-addr.arpa |
| some of the low order address octets might be missing |
| and should be set to zero. */ |
| for (cp1 = name; cp1 != penchunk; cp1 += strlen(cp1)+1) |
| { |
| /* check for digits only (weeds out things like |
| 50.0/24.67.28.64.in-addr.arpa which are used |
| as CNAME targets according to RFC 2317 */ |
| char *cp; |
| for (cp = cp1; *cp; cp++) |
| if (!isdigit((unsigned char)*cp)) |
| return 0; |
| |
| addr[3] = addr[2]; |
| addr[2] = addr[1]; |
| addr[1] = addr[0]; |
| addr[0] = atoi(cp1); |
| } |
| |
| return F_IPV4; |
| } |
| #ifdef HAVE_IPV6 |
| else if (hostname_isequal(penchunk, "ip6") && |
| (hostname_isequal(lastchunk, "int") || hostname_isequal(lastchunk, "arpa"))) |
| { |
| /* IP v6: |
| Address arrives as 0.1.2.3.4.5.6.7.8.9.a.b.c.d.e.f.ip6.[int|arpa] |
| or \[xfedcba9876543210fedcba9876543210/128].ip6.[int|arpa] |
| |
| Note that most of these the various reprentations are obsolete and |
| left-over from the many DNS-for-IPv6 wars. We support all the formats |
| that we can since there is no reason not to. |
| */ |
| |
| if (*name == '\\' && *(name+1) == '[' && |
| (*(name+2) == 'x' || *(name+2) == 'X')) |
| { |
| for (j = 0, cp1 = name+3; *cp1 && isxdigit((unsigned char) *cp1) && j < 32; cp1++, j++) |
| { |
| char xdig[2]; |
| xdig[0] = *cp1; |
| xdig[1] = 0; |
| if (j%2) |
| addr[j/2] |= strtol(xdig, NULL, 16); |
| else |
| addr[j/2] = strtol(xdig, NULL, 16) << 4; |
| } |
| |
| if (*cp1 == '/' && j == 32) |
| return F_IPV6; |
| } |
| else |
| { |
| for (cp1 = name; cp1 != penchunk; cp1 += strlen(cp1)+1) |
| { |
| if (*(cp1+1) || !isxdigit((unsigned char)*cp1)) |
| return 0; |
| |
| for (j = sizeof(struct all_addr)-1; j>0; j--) |
| addr[j] = (addr[j] >> 4) | (addr[j-1] << 4); |
| addr[0] = (addr[0] >> 4) | (strtol(cp1, NULL, 16) << 4); |
| } |
| |
| return F_IPV6; |
| } |
| } |
| #endif |
| |
| return 0; |
| } |
| |
| static unsigned char *skip_name(unsigned char *ansp, struct dns_header *header, size_t plen, int extrabytes) |
| { |
| while(1) |
| { |
| unsigned int label_type; |
| |
| if (!CHECK_LEN(header, ansp, plen, 1)) |
| return NULL; |
| |
| label_type = (*ansp) & 0xc0; |
| |
| if (label_type == 0xc0) |
| { |
| /* pointer for compression. */ |
| ansp += 2; |
| break; |
| } |
| else if (label_type == 0x80) |
| return NULL; /* reserved */ |
| else if (label_type == 0x40) |
| { |
| /* Extended label type */ |
| unsigned int count; |
| |
| if (!CHECK_LEN(header, ansp, plen, 2)) |
| return NULL; |
| |
| if (((*ansp++) & 0x3f) != 1) |
| return NULL; /* we only understand bitstrings */ |
| |
| count = *(ansp++); /* Bits in bitstring */ |
| |
| if (count == 0) /* count == 0 means 256 bits */ |
| ansp += 32; |
| else |
| ansp += ((count-1)>>3)+1; |
| } |
| else |
| { /* label type == 0 Bottom six bits is length */ |
| unsigned int len = (*ansp++) & 0x3f; |
| |
| if (!ADD_RDLEN(header, ansp, plen, len)) |
| return NULL; |
| |
| if (len == 0) |
| break; /* zero length label marks the end. */ |
| } |
| } |
| |
| if (!CHECK_LEN(header, ansp, plen, extrabytes)) |
| return NULL; |
| |
| return ansp; |
| } |
| |
| static unsigned char *skip_questions(struct dns_header *header, size_t plen) |
| { |
| int q; |
| unsigned char *ansp = (unsigned char *)(header+1); |
| |
| for (q = ntohs(header->qdcount); q != 0; q--) |
| { |
| if (!(ansp = skip_name(ansp, header, plen, 4))) |
| return NULL; |
| ansp += 4; /* class and type */ |
| } |
| |
| return ansp; |
| } |
| |
| static unsigned char *skip_section(unsigned char *ansp, int count, struct dns_header *header, size_t plen) |
| { |
| int i, rdlen; |
| |
| for (i = 0; i < count; i++) |
| { |
| if (!(ansp = skip_name(ansp, header, plen, 10))) |
| return NULL; |
| ansp += 8; /* type, class, TTL */ |
| GETSHORT(rdlen, ansp); |
| if (!ADD_RDLEN(header, ansp, plen, rdlen)) |
| return NULL; |
| } |
| |
| return ansp; |
| } |
| |
| /* CRC the question section. This is used to safely detect query |
| retransmision and to detect answers to questions we didn't ask, which |
| might be poisoning attacks. Note that we decode the name rather |
| than CRC the raw bytes, since replies might be compressed differently. |
| We ignore case in the names for the same reason. Return all-ones |
| if there is not question section. */ |
| unsigned int questions_crc(struct dns_header *header, size_t plen, char *name) |
| { |
| int q; |
| unsigned int crc = 0xffffffff; |
| unsigned char *p1, *p = (unsigned char *)(header+1); |
| |
| for (q = ntohs(header->qdcount); q != 0; q--) |
| { |
| if (!extract_name(header, plen, &p, name, 1, 4)) |
| return crc; /* bad packet */ |
| |
| for (p1 = (unsigned char *)name; *p1; p1++) |
| { |
| int i = 8; |
| char c = *p1; |
| |
| if (c >= 'A' && c <= 'Z') |
| c += 'a' - 'A'; |
| |
| crc ^= c << 24; |
| while (i--) |
| crc = crc & 0x80000000 ? (crc << 1) ^ 0x04c11db7 : crc << 1; |
| } |
| |
| /* CRC the class and type as well */ |
| for (p1 = p; p1 < p+4; p1++) |
| { |
| int i = 8; |
| crc ^= *p1 << 24; |
| while (i--) |
| crc = crc & 0x80000000 ? (crc << 1) ^ 0x04c11db7 : crc << 1; |
| } |
| |
| p += 4; |
| if (!CHECK_LEN(header, p, plen, 0)) |
| return crc; /* bad packet */ |
| } |
| |
| return crc; |
| } |
| |
| |
| size_t resize_packet(struct dns_header *header, size_t plen, unsigned char *pheader, size_t hlen) |
| { |
| unsigned char *ansp = skip_questions(header, plen); |
| |
| /* if packet is malformed, just return as-is. */ |
| if (!ansp) |
| return plen; |
| |
| if (!(ansp = skip_section(ansp, ntohs(header->ancount) + ntohs(header->nscount) + ntohs(header->arcount), |
| header, plen))) |
| return plen; |
| |
| /* restore pseudoheader */ |
| if (pheader && ntohs(header->arcount) == 0) |
| { |
| /* must use memmove, may overlap */ |
| memmove(ansp, pheader, hlen); |
| header->arcount = htons(1); |
| ansp += hlen; |
| } |
| |
| return ansp - (unsigned char *)header; |
| } |
| |
| unsigned char *find_pseudoheader(struct dns_header *header, size_t plen, size_t *len, unsigned char **p, int *is_sign) |
| { |
| /* See if packet has an RFC2671 pseudoheader, and if so return a pointer to it. |
| also return length of pseudoheader in *len and pointer to the UDP size in *p |
| Finally, check to see if a packet is signed. If it is we cannot change a single bit before |
| forwarding. We look for SIG and TSIG in the addition section, and TKEY queries (for GSS-TSIG) */ |
| |
| int i, arcount = ntohs(header->arcount); |
| unsigned char *ansp = (unsigned char *)(header+1); |
| unsigned short rdlen, type, class; |
| unsigned char *ret = NULL; |
| |
| if (is_sign) |
| { |
| *is_sign = 0; |
| |
| if (OPCODE(header) == QUERY) |
| { |
| for (i = ntohs(header->qdcount); i != 0; i--) |
| { |
| if (!(ansp = skip_name(ansp, header, plen, 4))) |
| return NULL; |
| |
| GETSHORT(type, ansp); |
| GETSHORT(class, ansp); |
| |
| if (class == C_IN && type == T_TKEY) |
| *is_sign = 1; |
| } |
| } |
| } |
| else |
| { |
| if (!(ansp = skip_questions(header, plen))) |
| return NULL; |
| } |
| |
| if (arcount == 0) |
| return NULL; |
| |
| if (!(ansp = skip_section(ansp, ntohs(header->ancount) + ntohs(header->nscount), header, plen))) |
| return NULL; |
| |
| for (i = 0; i < arcount; i++) |
| { |
| unsigned char *save, *start = ansp; |
| if (!(ansp = skip_name(ansp, header, plen, 10))) |
| return NULL; |
| |
| GETSHORT(type, ansp); |
| save = ansp; |
| GETSHORT(class, ansp); |
| ansp += 4; /* TTL */ |
| GETSHORT(rdlen, ansp); |
| if (!ADD_RDLEN(header, ansp, plen, rdlen)) |
| return NULL; |
| if (type == T_OPT) |
| { |
| if (len) |
| *len = ansp - start; |
| if (p) |
| *p = save; |
| ret = start; |
| } |
| else if (is_sign && |
| i == arcount - 1 && |
| class == C_ANY && |
| (type == T_SIG || type == T_TSIG)) |
| *is_sign = 1; |
| } |
| |
| return ret; |
| } |
| |
| struct macparm { |
| unsigned char *limit; |
| struct dns_header *header; |
| size_t plen; |
| union mysockaddr *l3; |
| }; |
| |
| static int filter_mac(int family, char *addrp, char *mac, size_t maclen, void *parmv) |
| { |
| struct macparm *parm = parmv; |
| int match = 0; |
| unsigned short rdlen; |
| struct dns_header *header = parm->header; |
| unsigned char *lenp, *datap, *p; |
| |
| if (family == parm->l3->sa.sa_family) |
| { |
| if (family == AF_INET && memcmp (&parm->l3->in.sin_addr, addrp, INADDRSZ) == 0) |
| match = 1; |
| #ifdef HAVE_IPV6 |
| else |
| if (family == AF_INET6 && memcmp (&parm->l3->in6.sin6_addr, addrp, IN6ADDRSZ) == 0) |
| match = 1; |
| #endif |
| } |
| |
| if (!match) |
| return 1; /* continue */ |
| |
| if (ntohs(header->arcount) == 0) |
| { |
| /* We are adding the pseudoheader */ |
| if (!(p = skip_questions(header, parm->plen)) || |
| !(p = skip_section(p, |
| ntohs(header->ancount) + ntohs(header->nscount), |
| header, parm->plen))) |
| return 0; |
| *p++ = 0; /* empty name */ |
| PUTSHORT(T_OPT, p); |
| PUTSHORT(PACKETSZ, p); /* max packet length - is 512 suitable default for non-EDNS0 resolvers? */ |
| PUTLONG(0, p); /* extended RCODE */ |
| lenp = p; |
| PUTSHORT(0, p); /* RDLEN */ |
| rdlen = 0; |
| if (((ssize_t)maclen) > (parm->limit - (p + 4))) |
| return 0; /* Too big */ |
| header->arcount = htons(1); |
| datap = p; |
| } |
| else |
| { |
| int i, is_sign; |
| unsigned short code, len; |
| |
| if (ntohs(header->arcount) != 1 || |
| !(p = find_pseudoheader(header, parm->plen, NULL, NULL, &is_sign)) || |
| is_sign || |
| (!(p = skip_name(p, header, parm->plen, 10)))) |
| return 0; |
| |
| p += 8; /* skip UDP length and RCODE */ |
| |
| lenp = p; |
| GETSHORT(rdlen, p); |
| if (!CHECK_LEN(header, p, parm->plen, rdlen)) |
| return 0; /* bad packet */ |
| datap = p; |
| |
| /* check if option already there */ |
| for (i = 0; i + 4 < rdlen; i += len + 4) |
| { |
| GETSHORT(code, p); |
| GETSHORT(len, p); |
| if (code == EDNS0_OPTION_MAC) |
| return 0; |
| p += len; |
| } |
| |
| if (((ssize_t)maclen) > (parm->limit - (p + 4))) |
| return 0; /* Too big */ |
| } |
| |
| PUTSHORT(EDNS0_OPTION_MAC, p); |
| PUTSHORT(maclen, p); |
| memcpy(p, mac, maclen); |
| p += maclen; |
| |
| PUTSHORT(p - datap, lenp); |
| parm->plen = p - (unsigned char *)header; |
| |
| return 0; /* done */ |
| } |
| |
| |
| size_t add_mac(struct dns_header *header, size_t plen, char *limit, union mysockaddr *l3) |
| { |
| struct macparm parm; |
| |
| /* Must have an existing pseudoheader as the only ar-record, |
| or have no ar-records. Must also not be signed */ |
| |
| if (ntohs(header->arcount) > 1) |
| return plen; |
| |
| parm.header = header; |
| parm.limit = (unsigned char *)limit; |
| parm.plen = plen; |
| parm.l3 = l3; |
| |
| iface_enumerate(AF_UNSPEC, &parm, filter_mac); |
| |
| return parm.plen; |
| } |
| |
| |
| /* is addr in the non-globally-routed IP space? */ |
| static int private_net(struct in_addr addr, int ban_localhost) |
| { |
| in_addr_t ip_addr = ntohl(addr.s_addr); |
| |
| return |
| (((ip_addr & 0xFF000000) == 0x7F000000) && ban_localhost) /* 127.0.0.0/8 (loopback) */ || |
| ((ip_addr & 0xFFFF0000) == 0xC0A80000) /* 192.168.0.0/16 (private) */ || |
| ((ip_addr & 0xFF000000) == 0x0A000000) /* 10.0.0.0/8 (private) */ || |
| ((ip_addr & 0xFFF00000) == 0xAC100000) /* 172.16.0.0/12 (private) */ || |
| ((ip_addr & 0xFFFF0000) == 0xA9FE0000) /* 169.254.0.0/16 (zeroconf) */ ; |
| } |
| |
| static unsigned char *do_doctor(unsigned char *p, int count, struct dns_header *header, size_t qlen, char *name) |
| { |
| int i, qtype, qclass, rdlen; |
| |
| for (i = count; i != 0; i--) |
| { |
| if (name && option_bool(OPT_LOG)) |
| { |
| if (!extract_name(header, qlen, &p, name, 1, 10)) |
| return 0; |
| } |
| else if (!(p = skip_name(p, header, qlen, 10))) |
| return 0; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| p += 4; /* ttl */ |
| GETSHORT(rdlen, p); |
| |
| if (qclass == C_IN && qtype == T_A) |
| { |
| struct doctor *doctor; |
| struct in_addr addr; |
| |
| if (!CHECK_LEN(header, p, qlen, INADDRSZ)) |
| return 0; |
| |
| /* alignment */ |
| memcpy(&addr, p, INADDRSZ); |
| |
| for (doctor = daemon->doctors; doctor; doctor = doctor->next) |
| { |
| if (doctor->end.s_addr == 0) |
| { |
| if (!is_same_net(doctor->in, addr, doctor->mask)) |
| continue; |
| } |
| else if (ntohl(doctor->in.s_addr) > ntohl(addr.s_addr) || |
| ntohl(doctor->end.s_addr) < ntohl(addr.s_addr)) |
| continue; |
| |
| addr.s_addr &= ~doctor->mask.s_addr; |
| addr.s_addr |= (doctor->out.s_addr & doctor->mask.s_addr); |
| /* Since we munged the data, the server it came from is no longer authoritative */ |
| header->hb3 &= ~HB3_AA; |
| memcpy(p, &addr, INADDRSZ); |
| break; |
| } |
| } |
| else if (qtype == T_TXT && name && option_bool(OPT_LOG)) |
| { |
| unsigned char *p1 = p; |
| if (!CHECK_LEN(header, p1, qlen, rdlen)) |
| return 0; |
| while ((p1 - p) < rdlen) |
| { |
| unsigned int i, len = *p1; |
| unsigned char *p2 = p1; |
| /* make counted string zero-term and sanitise */ |
| for (i = 0; i < len; i++) |
| if (isprint(*(p2+1))) |
| { |
| *p2 = *(p2+1); |
| p2++; |
| } |
| *p2 = 0; |
| my_syslog(LOG_INFO, "reply %s is %s", name, p1); |
| /* restore */ |
| memmove(p1 + 1, p1, len); |
| *p1 = len; |
| p1 += len+1; |
| } |
| } |
| |
| if (!ADD_RDLEN(header, p, qlen, rdlen)) |
| return 0; /* bad packet */ |
| } |
| |
| return p; |
| } |
| |
| static int find_soa(struct dns_header *header, size_t qlen, char *name) |
| { |
| unsigned char *p; |
| int qtype, qclass, rdlen; |
| unsigned long ttl, minttl = ULONG_MAX; |
| int i, found_soa = 0; |
| |
| /* first move to NS section and find TTL from any SOA section */ |
| if (!(p = skip_questions(header, qlen)) || |
| !(p = do_doctor(p, ntohs(header->ancount), header, qlen, name))) |
| return 0; /* bad packet */ |
| |
| for (i = ntohs(header->nscount); i != 0; i--) |
| { |
| if (!(p = skip_name(p, header, qlen, 10))) |
| return 0; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| GETLONG(ttl, p); |
| GETSHORT(rdlen, p); |
| |
| if ((qclass == C_IN) && (qtype == T_SOA)) |
| { |
| found_soa = 1; |
| if (ttl < minttl) |
| minttl = ttl; |
| |
| /* MNAME */ |
| if (!(p = skip_name(p, header, qlen, 0))) |
| return 0; |
| /* RNAME */ |
| if (!(p = skip_name(p, header, qlen, 20))) |
| return 0; |
| p += 16; /* SERIAL REFRESH RETRY EXPIRE */ |
| |
| GETLONG(ttl, p); /* minTTL */ |
| if (ttl < minttl) |
| minttl = ttl; |
| } |
| else if (!ADD_RDLEN(header, p, qlen, rdlen)) |
| return 0; /* bad packet */ |
| } |
| |
| /* rewrite addresses in additioal section too */ |
| if (!do_doctor(p, ntohs(header->arcount), header, qlen, NULL)) |
| return 0; |
| |
| if (!found_soa) |
| minttl = daemon->neg_ttl; |
| |
| return minttl; |
| } |
| |
| /* Note that the following code can create CNAME chains that don't point to a real record, |
| either because of lack of memory, or lack of SOA records. These are treated by the cache code as |
| expired and cleaned out that way. |
| Return 1 if we reject an address because it look like part of dns-rebinding attack. */ |
| int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t now, |
| int is_sign, int check_rebind, int checking_disabled) |
| { |
| unsigned char *p, *p1, *endrr, *namep; |
| int i, j, qtype, qclass, aqtype, aqclass, ardlen, res, searched_soa = 0; |
| unsigned long ttl = 0; |
| struct all_addr addr; |
| |
| cache_start_insert(); |
| |
| /* find_soa is needed for dns_doctor and logging side-effects, so don't call it lazily if there are any. */ |
| if (daemon->doctors || option_bool(OPT_LOG)) |
| { |
| searched_soa = 1; |
| ttl = find_soa(header, qlen, name); |
| } |
| |
| /* go through the questions. */ |
| p = (unsigned char *)(header+1); |
| |
| for (i = ntohs(header->qdcount); i != 0; i--) |
| { |
| int found = 0, cname_count = 5; |
| struct crec *cpp = NULL; |
| int flags = RCODE(header) == NXDOMAIN ? F_NXDOMAIN : 0; |
| unsigned long cttl = ULONG_MAX, attl; |
| |
| namep = p; |
| if (!extract_name(header, qlen, &p, name, 1, 4)) |
| return 0; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| |
| if (qclass != C_IN) |
| continue; |
| |
| /* PTRs: we chase CNAMEs here, since we have no way to |
| represent them in the cache. */ |
| if (qtype == T_PTR) |
| { |
| int name_encoding = in_arpa_name_2_addr(name, &addr); |
| |
| if (!name_encoding) |
| continue; |
| |
| if (!(flags & F_NXDOMAIN)) |
| { |
| cname_loop: |
| if (!(p1 = skip_questions(header, qlen))) |
| return 0; |
| |
| for (j = ntohs(header->ancount); j != 0; j--) |
| { |
| unsigned char *tmp = namep; |
| /* the loop body overwrites the original name, so get it back here. */ |
| if (!extract_name(header, qlen, &tmp, name, 1, 0) || |
| !(res = extract_name(header, qlen, &p1, name, 0, 10))) |
| return 0; /* bad packet */ |
| |
| GETSHORT(aqtype, p1); |
| GETSHORT(aqclass, p1); |
| GETLONG(attl, p1); |
| if ((daemon->max_ttl != 0) && (attl > daemon->max_ttl) && !is_sign) |
| { |
| (p1) -= 4; |
| PUTLONG(daemon->max_ttl, p1); |
| } |
| GETSHORT(ardlen, p1); |
| endrr = p1+ardlen; |
| |
| /* TTL of record is minimum of CNAMES and PTR */ |
| if (attl < cttl) |
| cttl = attl; |
| |
| if (aqclass == C_IN && res != 2 && (aqtype == T_CNAME || aqtype == T_PTR)) |
| { |
| if (!extract_name(header, qlen, &p1, name, 1, 0)) |
| return 0; |
| |
| if (aqtype == T_CNAME) |
| { |
| if (!cname_count--) |
| return 0; /* looped CNAMES */ |
| goto cname_loop; |
| } |
| |
| cache_insert(name, &addr, now, cttl, name_encoding | F_REVERSE); |
| found = 1; |
| } |
| |
| p1 = endrr; |
| if (!CHECK_LEN(header, p1, qlen, 0)) |
| return 0; /* bad packet */ |
| } |
| } |
| |
| if (!found && !option_bool(OPT_NO_NEG)) |
| { |
| if (!searched_soa) |
| { |
| searched_soa = 1; |
| ttl = find_soa(header, qlen, NULL); |
| } |
| if (ttl) |
| cache_insert(NULL, &addr, now, ttl, name_encoding | F_REVERSE | F_NEG | flags); |
| } |
| } |
| else |
| { |
| /* everything other than PTR */ |
| struct crec *newc; |
| int addrlen; |
| |
| if (qtype == T_A) |
| { |
| addrlen = INADDRSZ; |
| flags |= F_IPV4; |
| } |
| #ifdef HAVE_IPV6 |
| else if (qtype == T_AAAA) |
| { |
| addrlen = IN6ADDRSZ; |
| flags |= F_IPV6; |
| } |
| #endif |
| else |
| continue; |
| |
| if (!(flags & F_NXDOMAIN)) |
| { |
| cname_loop1: |
| if (!(p1 = skip_questions(header, qlen))) |
| return 0; |
| |
| for (j = ntohs(header->ancount); j != 0; j--) |
| { |
| if (!(res = extract_name(header, qlen, &p1, name, 0, 10))) |
| return 0; /* bad packet */ |
| |
| GETSHORT(aqtype, p1); |
| GETSHORT(aqclass, p1); |
| GETLONG(attl, p1); |
| if ((daemon->max_ttl != 0) && (attl > daemon->max_ttl) && !is_sign) |
| { |
| (p1) -= 4; |
| PUTLONG(daemon->max_ttl, p1); |
| } |
| GETSHORT(ardlen, p1); |
| endrr = p1+ardlen; |
| |
| if (aqclass == C_IN && res != 2 && (aqtype == T_CNAME || aqtype == qtype)) |
| { |
| if (aqtype == T_CNAME) |
| { |
| if (!cname_count--) |
| return 0; /* looped CNAMES */ |
| newc = cache_insert(name, NULL, now, attl, F_CNAME | F_FORWARD); |
| if (newc && cpp) |
| { |
| cpp->addr.cname.cache = newc; |
| cpp->addr.cname.uid = newc->uid; |
| } |
| |
| cpp = newc; |
| if (attl < cttl) |
| cttl = attl; |
| |
| if (!extract_name(header, qlen, &p1, name, 1, 0)) |
| return 0; |
| goto cname_loop1; |
| } |
| else |
| { |
| found = 1; |
| |
| /* copy address into aligned storage */ |
| if (!CHECK_LEN(header, p1, qlen, addrlen)) |
| return 0; /* bad packet */ |
| memcpy(&addr, p1, addrlen); |
| |
| /* check for returned address in private space */ |
| if (check_rebind && |
| (flags & F_IPV4) && |
| private_net(addr.addr.addr4, !option_bool(OPT_LOCAL_REBIND))) |
| return 1; |
| |
| newc = cache_insert(name, &addr, now, attl, flags | F_FORWARD); |
| if (newc && cpp) |
| { |
| cpp->addr.cname.cache = newc; |
| cpp->addr.cname.uid = newc->uid; |
| } |
| cpp = NULL; |
| } |
| } |
| |
| p1 = endrr; |
| if (!CHECK_LEN(header, p1, qlen, 0)) |
| return 0; /* bad packet */ |
| } |
| } |
| |
| if (!found && !option_bool(OPT_NO_NEG)) |
| { |
| if (!searched_soa) |
| { |
| searched_soa = 1; |
| ttl = find_soa(header, qlen, NULL); |
| } |
| /* If there's no SOA to get the TTL from, but there is a CNAME |
| pointing at this, inherit its TTL */ |
| if (ttl || cpp) |
| { |
| newc = cache_insert(name, NULL, now, ttl ? ttl : cttl, F_FORWARD | F_NEG | flags); |
| if (newc && cpp) |
| { |
| cpp->addr.cname.cache = newc; |
| cpp->addr.cname.uid = newc->uid; |
| } |
| } |
| } |
| } |
| } |
| |
| /* Don't put stuff from a truncated packet into the cache, |
| also 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->hb3 & HB3_TC) && !(header->hb4 & HB4_CD) && !checking_disabled) |
| cache_end_insert(); |
| |
| return 0; |
| } |
| |
| /* If the packet holds exactly one query |
| return F_IPV4 or F_IPV6 and leave the name from the query in name */ |
| |
| unsigned int extract_request(struct dns_header *header, size_t qlen, char *name, unsigned short *typep) |
| { |
| unsigned char *p = (unsigned char *)(header+1); |
| int qtype, qclass; |
| |
| if (typep) |
| *typep = 0; |
| |
| if (ntohs(header->qdcount) != 1 || OPCODE(header) != QUERY) |
| return 0; /* must be exactly one query. */ |
| |
| if (!extract_name(header, qlen, &p, name, 1, 4)) |
| return 0; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| |
| if (typep) |
| *typep = qtype; |
| |
| if (qclass == C_IN) |
| { |
| if (qtype == T_A) |
| return F_IPV4; |
| if (qtype == T_AAAA) |
| return F_IPV6; |
| if (qtype == T_ANY) |
| return F_IPV4 | F_IPV6; |
| } |
| |
| return F_QUERY; |
| } |
| |
| |
| size_t setup_reply(struct dns_header *header, size_t qlen, |
| struct all_addr *addrp, unsigned int flags, unsigned long ttl) |
| { |
| unsigned char *p = skip_questions(header, qlen); |
| |
| /* clear authoritative and truncated flags, set QR flag */ |
| header->hb3 = (header->hb3 & ~(HB3_AA | HB3_TC)) | HB3_QR; |
| /* set RA flag */ |
| header->hb4 |= HB4_RA; |
| |
| header->nscount = htons(0); |
| header->arcount = htons(0); |
| header->ancount = htons(0); /* no answers unless changed below */ |
| if (flags == F_NEG) |
| SET_RCODE(header, SERVFAIL); /* couldn't get memory */ |
| else if (flags == F_NOERR) |
| SET_RCODE(header, NOERROR); /* empty domain */ |
| else if (flags == F_NXDOMAIN) |
| SET_RCODE(header, NXDOMAIN); |
| else if (p && flags == F_IPV4) |
| { /* we know the address */ |
| SET_RCODE(header, NOERROR); |
| header->ancount = htons(1); |
| header->hb3 |= HB3_AA; |
| add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_A, C_IN, "4", addrp); |
| } |
| #ifdef HAVE_IPV6 |
| else if (p && flags == F_IPV6) |
| { |
| SET_RCODE(header, NOERROR); |
| header->ancount = htons(1); |
| header->hb3 |= HB3_AA; |
| add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_AAAA, C_IN, "6", addrp); |
| } |
| #endif |
| else /* nowhere to forward to */ |
| SET_RCODE(header, REFUSED); |
| |
| return p - (unsigned char *)header; |
| } |
| |
| /* check if name matches local names ie from /etc/hosts or DHCP or local mx names. */ |
| int check_for_local_domain(char *name, time_t now) |
| { |
| struct crec *crecp; |
| struct mx_srv_record *mx; |
| struct txt_record *txt; |
| struct interface_name *intr; |
| struct ptr_record *ptr; |
| struct naptr *naptr; |
| |
| if ((crecp = cache_find_by_name(NULL, name, now, F_IPV4 | F_IPV6 | F_CNAME)) && |
| (crecp->flags & (F_HOSTS | F_DHCP))) |
| return 1; |
| |
| for (naptr = daemon->naptr; naptr; naptr = naptr->next) |
| if (hostname_isequal(name, naptr->name)) |
| return 1; |
| |
| for (mx = daemon->mxnames; mx; mx = mx->next) |
| if (hostname_isequal(name, mx->name)) |
| return 1; |
| |
| for (txt = daemon->txt; txt; txt = txt->next) |
| if (hostname_isequal(name, txt->name)) |
| return 1; |
| |
| for (intr = daemon->int_names; intr; intr = intr->next) |
| if (hostname_isequal(name, intr->name)) |
| return 1; |
| |
| for (ptr = daemon->ptr; ptr; ptr = ptr->next) |
| if (hostname_isequal(name, ptr->name)) |
| return 1; |
| |
| return 0; |
| } |
| |
| /* Is the packet a reply with the answer address equal to addr? |
| If so mung is into an NXDOMAIN reply and also put that information |
| in the cache. */ |
| int check_for_bogus_wildcard(struct dns_header *header, size_t qlen, char *name, |
| struct bogus_addr *baddr, time_t now) |
| { |
| unsigned char *p; |
| int i, qtype, qclass, rdlen; |
| unsigned long ttl; |
| struct bogus_addr *baddrp; |
| |
| /* skip over questions */ |
| if (!(p = skip_questions(header, qlen))) |
| return 0; /* bad packet */ |
| |
| for (i = ntohs(header->ancount); i != 0; i--) |
| { |
| if (!extract_name(header, qlen, &p, name, 1, 10)) |
| return 0; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| GETLONG(ttl, p); |
| GETSHORT(rdlen, p); |
| |
| if (qclass == C_IN && qtype == T_A) |
| { |
| if (!CHECK_LEN(header, p, qlen, INADDRSZ)) |
| return 0; |
| |
| for (baddrp = baddr; baddrp; baddrp = baddrp->next) |
| if (memcmp(&baddrp->addr, p, INADDRSZ) == 0) |
| { |
| /* Found a bogus address. Insert that info here, since there no SOA record |
| to get the ttl from in the normal processing */ |
| cache_start_insert(); |
| cache_insert(name, NULL, now, ttl, F_IPV4 | F_FORWARD | F_NEG | F_NXDOMAIN | F_CONFIG); |
| cache_end_insert(); |
| |
| return 1; |
| } |
| } |
| |
| if (!ADD_RDLEN(header, p, qlen, rdlen)) |
| return 0; |
| } |
| |
| return 0; |
| } |
| |
| static int add_resource_record(struct dns_header *header, char *limit, int *truncp, unsigned int nameoffset, unsigned char **pp, |
| unsigned long ttl, unsigned int *offset, unsigned short type, unsigned short class, char *format, ...) |
| { |
| va_list ap; |
| unsigned char *sav, *p = *pp; |
| int j; |
| unsigned short usval; |
| long lval; |
| char *sval; |
| |
| if (truncp && *truncp) |
| return 0; |
| |
| PUTSHORT(nameoffset | 0xc000, p); |
| PUTSHORT(type, p); |
| PUTSHORT(class, p); |
| PUTLONG(ttl, p); /* TTL */ |
| |
| sav = p; /* Save pointer to RDLength field */ |
| PUTSHORT(0, p); /* Placeholder RDLength */ |
| |
| va_start(ap, format); /* make ap point to 1st unamed argument */ |
| |
| for (; *format; format++) |
| switch (*format) |
| { |
| #ifdef HAVE_IPV6 |
| case '6': |
| sval = va_arg(ap, char *); |
| memcpy(p, sval, IN6ADDRSZ); |
| p += IN6ADDRSZ; |
| break; |
| #endif |
| |
| case '4': |
| sval = va_arg(ap, char *); |
| memcpy(p, sval, INADDRSZ); |
| p += INADDRSZ; |
| break; |
| |
| case 's': |
| usval = va_arg(ap, int); |
| PUTSHORT(usval, p); |
| break; |
| |
| case 'l': |
| lval = va_arg(ap, long); |
| PUTLONG(lval, p); |
| break; |
| |
| case 'd': |
| /* get domain-name answer arg and store it in RDATA field */ |
| if (offset) |
| *offset = p - (unsigned char *)header; |
| p = do_rfc1035_name(p, va_arg(ap, char *)); |
| *p++ = 0; |
| break; |
| |
| case 't': |
| usval = va_arg(ap, int); |
| sval = va_arg(ap, char *); |
| memcpy(p, sval, usval); |
| p += usval; |
| break; |
| |
| case 'z': |
| sval = va_arg(ap, char *); |
| usval = sval ? strlen(sval) : 0; |
| if (usval > 255) |
| usval = 255; |
| *p++ = (unsigned char)usval; |
| memcpy(p, sval, usval); |
| p += usval; |
| break; |
| } |
| |
| va_end(ap); /* clean up variable argument pointer */ |
| |
| j = p - sav - 2; |
| PUTSHORT(j, sav); /* Now, store real RDLength */ |
| |
| /* check for overflow of buffer */ |
| if (limit && ((unsigned char *)limit - p) < 0) |
| { |
| if (truncp) |
| *truncp = 1; |
| return 0; |
| } |
| |
| *pp = p; |
| return 1; |
| } |
| |
| static unsigned long crec_ttl(struct crec *crecp, time_t now) |
| { |
| /* Return 0 ttl for DHCP entries, which might change |
| before the lease expires. */ |
| |
| if (crecp->flags & (F_IMMORTAL | F_DHCP)) |
| return daemon->local_ttl; |
| |
| /* Return the Max TTL value if it is lower then the actual TTL */ |
| if (daemon->max_ttl == 0 || ((unsigned)(crecp->ttd - now) < daemon->max_ttl)) |
| return crecp->ttd - now; |
| else |
| return daemon->max_ttl; |
| } |
| |
| |
| /* return zero if we can't answer from cache, or packet size if we can */ |
| size_t answer_request(struct dns_header *header, char *limit, size_t qlen, |
| struct in_addr local_addr, struct in_addr local_netmask, time_t now) |
| { |
| char *name = daemon->namebuff; |
| unsigned char *p, *ansp, *pheader; |
| int qtype, qclass; |
| struct all_addr addr; |
| unsigned int nameoffset; |
| unsigned short flag; |
| int q, ans, anscount = 0, addncount = 0; |
| int dryrun = 0, sec_reqd = 0; |
| int is_sign; |
| struct crec *crecp; |
| int nxdomain = 0, auth = 1, trunc = 0; |
| struct mx_srv_record *rec; |
| |
| /* If there is an RFC2671 pseudoheader then it will be overwritten by |
| partial replies, so we have to do a dry run to see if we can answer |
| the query. We check to see if the do bit is set, if so we always |
| forward rather than answering from the cache, which doesn't include |
| security information. */ |
| |
| if (find_pseudoheader(header, qlen, NULL, &pheader, &is_sign)) |
| { |
| unsigned short udpsz, flags; |
| unsigned char *psave = pheader; |
| |
| GETSHORT(udpsz, pheader); |
| pheader += 2; /* ext_rcode */ |
| GETSHORT(flags, pheader); |
| |
| sec_reqd = flags & 0x8000; /* do bit */ |
| |
| /* If our client is advertising a larger UDP packet size |
| than we allow, trim it so that we don't get an overlarge |
| response from upstream */ |
| |
| if (!is_sign && (udpsz > daemon->edns_pktsz)) |
| PUTSHORT(daemon->edns_pktsz, psave); |
| |
| dryrun = 1; |
| } |
| |
| if (ntohs(header->qdcount) == 0 || OPCODE(header) != QUERY ) |
| return 0; |
| |
| for (rec = daemon->mxnames; rec; rec = rec->next) |
| rec->offset = 0; |
| |
| rerun: |
| /* determine end of question section (we put answers there) */ |
| if (!(ansp = skip_questions(header, qlen))) |
| return 0; /* bad packet */ |
| |
| /* now process each question, answers go in RRs after the question */ |
| p = (unsigned char *)(header+1); |
| |
| for (q = ntohs(header->qdcount); q != 0; q--) |
| { |
| /* save pointer to name for copying into answers */ |
| nameoffset = p - (unsigned char *)header; |
| |
| /* now extract name as .-concatenated string into name */ |
| if (!extract_name(header, qlen, &p, name, 1, 4)) |
| return 0; /* bad packet */ |
| |
| GETSHORT(qtype, p); |
| GETSHORT(qclass, p); |
| |
| ans = 0; /* have we answered this question */ |
| |
| if (qtype == T_TXT || qtype == T_ANY) |
| { |
| struct txt_record *t; |
| for(t = daemon->txt; t ; t = t->next) |
| { |
| if (t->class == qclass && hostname_isequal(name, t->name)) |
| { |
| ans = 1; |
| if (!dryrun) |
| { |
| log_query(F_CONFIG | F_RRNAME, name, NULL, "<TXT>"); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| daemon->local_ttl, NULL, |
| T_TXT, t->class, "t", t->len, t->txt)) |
| anscount++; |
| |
| } |
| } |
| } |
| } |
| |
| if (qclass == C_IN) |
| { |
| if (qtype == T_PTR || qtype == T_ANY) |
| { |
| /* see if it's w.z.y.z.in-addr.arpa format */ |
| int is_arpa = in_arpa_name_2_addr(name, &addr); |
| struct ptr_record *ptr; |
| struct interface_name* intr = NULL; |
| |
| for (ptr = daemon->ptr; ptr; ptr = ptr->next) |
| if (hostname_isequal(name, ptr->name)) |
| break; |
| |
| if (is_arpa == F_IPV4) |
| for (intr = daemon->int_names; intr; intr = intr->next) |
| { |
| if (addr.addr.addr4.s_addr == get_ifaddr(intr->intr).s_addr) |
| break; |
| else |
| while (intr->next && strcmp(intr->intr, intr->next->intr) == 0) |
| intr = intr->next; |
| } |
| |
| if (intr) |
| { |
| ans = 1; |
| if (!dryrun) |
| { |
| log_query(F_IPV4 | F_REVERSE | F_CONFIG, intr->name, &addr, NULL); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| daemon->local_ttl, NULL, |
| T_PTR, C_IN, "d", intr->name)) |
| anscount++; |
| } |
| } |
| else if (ptr) |
| { |
| ans = 1; |
| if (!dryrun) |
| { |
| log_query(F_CONFIG | F_RRNAME, name, NULL, "<PTR>"); |
| for (ptr = daemon->ptr; ptr; ptr = ptr->next) |
| if (hostname_isequal(name, ptr->name) && |
| add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| daemon->local_ttl, NULL, |
| T_PTR, C_IN, "d", ptr->ptr)) |
| anscount++; |
| |
| } |
| } |
| else if ((crecp = cache_find_by_addr(NULL, &addr, now, is_arpa))) |
| do |
| { |
| /* don't answer wildcard queries with data not from /etc/hosts or dhcp leases */ |
| if (qtype == T_ANY && !(crecp->flags & (F_HOSTS | F_DHCP))) |
| continue; |
| |
| if (crecp->flags & F_NEG) |
| { |
| ans = 1; |
| auth = 0; |
| if (crecp->flags & F_NXDOMAIN) |
| nxdomain = 1; |
| if (!dryrun) |
| log_query(crecp->flags & ~F_FORWARD, name, &addr, NULL); |
| } |
| else if ((crecp->flags & (F_HOSTS | F_DHCP)) || !sec_reqd) |
| { |
| ans = 1; |
| if (!(crecp->flags & (F_HOSTS | F_DHCP))) |
| auth = 0; |
| if (!dryrun) |
| { |
| log_query(crecp->flags & ~F_FORWARD, cache_get_name(crecp), &addr, |
| record_source(crecp->uid)); |
| |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| crec_ttl(crecp, now), NULL, |
| T_PTR, C_IN, "d", cache_get_name(crecp))) |
| anscount++; |
| } |
| } |
| } while ((crecp = cache_find_by_addr(crecp, &addr, now, is_arpa))); |
| else if (is_arpa == F_IPV4 && |
| option_bool(OPT_BOGUSPRIV) && |
| private_net(addr.addr.addr4, 1)) |
| { |
| /* if not in cache, enabled and private IPV4 address, return NXDOMAIN */ |
| ans = 1; |
| nxdomain = 1; |
| if (!dryrun) |
| log_query(F_CONFIG | F_REVERSE | F_IPV4 | F_NEG | F_NXDOMAIN, |
| name, &addr, NULL); |
| } |
| } |
| |
| for (flag = F_IPV4; flag; flag = (flag == F_IPV4) ? F_IPV6 : 0) |
| { |
| unsigned short type = T_A; |
| |
| if (flag == F_IPV6) |
| #ifdef HAVE_IPV6 |
| type = T_AAAA; |
| #else |
| break; |
| #endif |
| |
| if (qtype != type && qtype != T_ANY) |
| continue; |
| |
| /* Check for "A for A" queries; be rather conservative |
| about what looks like dotted-quad. */ |
| if (qtype == T_A) |
| { |
| char *cp; |
| unsigned int i, a; |
| int x; |
| |
| for (cp = name, i = 0, a = 0; *cp; i++) |
| { |
| if (!isdigit((unsigned char)*cp) || (x = strtol(cp, &cp, 10)) > 255) |
| { |
| i = 5; |
| break; |
| } |
| |
| a = (a << 8) + x; |
| |
| if (*cp == '.') |
| cp++; |
| } |
| |
| if (i == 4) |
| { |
| ans = 1; |
| if (!dryrun) |
| { |
| addr.addr.addr4.s_addr = htonl(a); |
| log_query(F_FORWARD | F_CONFIG | F_IPV4, name, &addr, NULL); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| daemon->local_ttl, NULL, type, C_IN, "4", &addr)) |
| anscount++; |
| } |
| continue; |
| } |
| } |
| |
| /* interface name stuff */ |
| if (qtype == T_A) |
| { |
| struct interface_name *intr; |
| |
| for (intr = daemon->int_names; intr; intr = intr->next) |
| if (hostname_isequal(name, intr->name)) |
| break; |
| |
| if (intr) |
| { |
| ans = 1; |
| if (!dryrun) |
| { |
| if ((addr.addr.addr4 = get_ifaddr(intr->intr)).s_addr == (in_addr_t) -1) |
| log_query(F_FORWARD | F_CONFIG | F_IPV4 | F_NEG, name, NULL, NULL); |
| else |
| { |
| log_query(F_FORWARD | F_CONFIG | F_IPV4, name, &addr, NULL); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| daemon->local_ttl, NULL, type, C_IN, "4", &addr)) |
| anscount++; |
| } |
| } |
| continue; |
| } |
| } |
| |
| cname_restart: |
| if ((crecp = cache_find_by_name(NULL, name, now, flag | F_CNAME))) |
| { |
| int localise = 0; |
| |
| /* See if a putative address is on the network from which we recieved |
| the query, is so we'll filter other answers. */ |
| if (local_addr.s_addr != 0 && option_bool(OPT_LOCALISE) && flag == F_IPV4) |
| { |
| struct crec *save = crecp; |
| do { |
| if ((crecp->flags & F_HOSTS) && |
| is_same_net(*((struct in_addr *)&crecp->addr), local_addr, local_netmask)) |
| { |
| localise = 1; |
| break; |
| } |
| } while ((crecp = cache_find_by_name(crecp, name, now, flag | F_CNAME))); |
| crecp = save; |
| } |
| |
| do |
| { |
| /* don't answer wildcard queries with data not from /etc/hosts |
| or DHCP leases */ |
| if (qtype == T_ANY && !(crecp->flags & (F_HOSTS | F_DHCP))) |
| break; |
| |
| if (crecp->flags & F_CNAME) |
| { |
| if (!dryrun) |
| { |
| log_query(crecp->flags, name, NULL, record_source(crecp->uid)); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| crec_ttl(crecp, now), &nameoffset, |
| T_CNAME, C_IN, "d", cache_get_name(crecp->addr.cname.cache))) |
| anscount++; |
| } |
| |
| strcpy(name, cache_get_name(crecp->addr.cname.cache)); |
| goto cname_restart; |
| } |
| |
| if (crecp->flags & F_NEG) |
| { |
| ans = 1; |
| auth = 0; |
| if (crecp->flags & F_NXDOMAIN) |
| nxdomain = 1; |
| if (!dryrun) |
| log_query(crecp->flags, name, NULL, NULL); |
| } |
| else if ((crecp->flags & (F_HOSTS | F_DHCP)) || !sec_reqd) |
| { |
| /* If we are returning local answers depending on network, |
| filter here. */ |
| if (localise && |
| (crecp->flags & F_HOSTS) && |
| !is_same_net(*((struct in_addr *)&crecp->addr), local_addr, local_netmask)) |
| continue; |
| |
| if (!(crecp->flags & (F_HOSTS | F_DHCP))) |
| auth = 0; |
| |
| ans = 1; |
| if (!dryrun) |
| { |
| log_query(crecp->flags & ~F_REVERSE, name, &crecp->addr.addr, |
| record_source(crecp->uid)); |
| |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, |
| crec_ttl(crecp, now), NULL, type, C_IN, |
| type == T_A ? "4" : "6", &crecp->addr)) |
| anscount++; |
| } |
| } |
| } while ((crecp = cache_find_by_name(crecp, name, now, flag | F_CNAME))); |
| } |
| } |
| |
| if (qtype == T_MX || qtype == T_ANY) |
| { |
| int found = 0; |
| for (rec = daemon->mxnames; rec; rec = rec->next) |
| if (!rec->issrv && hostname_isequal(name, rec->name)) |
| { |
| ans = found = 1; |
| if (!dryrun) |
| { |
| unsigned int offset; |
| log_query(F_CONFIG | F_RRNAME, name, NULL, "<MX>"); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, |
| &offset, T_MX, C_IN, "sd", rec->weight, rec->target)) |
| { |
| anscount++; |
| if (rec->target) |
| rec->offset = offset; |
| } |
| } |
| } |
| |
| if (!found && (option_bool(OPT_SELFMX) || option_bool(OPT_LOCALMX)) && |
| cache_find_by_name(NULL, name, now, F_HOSTS | F_DHCP)) |
| { |
| ans = 1; |
| if (!dryrun) |
| { |
| log_query(F_CONFIG | F_RRNAME, name, NULL, "<MX>"); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, NULL, |
| T_MX, C_IN, "sd", 1, |
| option_bool(OPT_SELFMX) ? name : daemon->mxtarget)) |
| anscount++; |
| } |
| } |
| } |
| |
| if (qtype == T_SRV || qtype == T_ANY) |
| { |
| int found = 0; |
| struct mx_srv_record *move = NULL, **up = &daemon->mxnames; |
| |
| for (rec = daemon->mxnames; rec; rec = rec->next) |
| if (rec->issrv && hostname_isequal(name, rec->name)) |
| { |
| found = ans = 1; |
| if (!dryrun) |
| { |
| unsigned int offset; |
| log_query(F_CONFIG | F_RRNAME, name, NULL, "<SRV>"); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, |
| &offset, T_SRV, C_IN, "sssd", |
| rec->priority, rec->weight, rec->srvport, rec->target)) |
| { |
| anscount++; |
| if (rec->target) |
| rec->offset = offset; |
| } |
| } |
| |
| /* unlink first SRV record found */ |
| if (!move) |
| { |
| move = rec; |
| *up = rec->next; |
| } |
| else |
| up = &rec->next; |
| } |
| else |
| up = &rec->next; |
| |
| /* put first SRV record back at the end. */ |
| if (move) |
| { |
| *up = move; |
| move->next = NULL; |
| } |
| |
| if (!found && option_bool(OPT_FILTER) && (qtype == T_SRV || (qtype == T_ANY && strchr(name, '_')))) |
| { |
| ans = 1; |
| if (!dryrun) |
| log_query(F_CONFIG | F_NEG, name, NULL, NULL); |
| } |
| } |
| |
| if (qtype == T_NAPTR || qtype == T_ANY) |
| { |
| struct naptr *na; |
| for (na = daemon->naptr; na; na = na->next) |
| if (hostname_isequal(name, na->name)) |
| { |
| ans = 1; |
| if (!dryrun) |
| { |
| log_query(F_CONFIG | F_RRNAME, name, NULL, "<NAPTR>"); |
| if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, |
| NULL, T_NAPTR, C_IN, "sszzzd", |
| na->order, na->pref, na->flags, na->services, na->regexp, na->replace)) |
| anscount++; |
| } |
| } |
| } |
| |
| if (qtype == T_MAILB) |
| ans = 1, nxdomain = 1; |
| |
| if (qtype == T_SOA && option_bool(OPT_FILTER)) |
| { |
| ans = 1; |
| if (!dryrun) |
| log_query(F_CONFIG | F_NEG, name, &addr, NULL); |
| } |
| } |
| |
| if (!ans) |
| return 0; /* failed to answer a question */ |
| } |
| |
| if (dryrun) |
| { |
| dryrun = 0; |
| goto rerun; |
| } |
| |
| /* create an additional data section, for stuff in SRV and MX record replies. */ |
| for (rec = daemon->mxnames; rec; rec = rec->next) |
| if (rec->offset != 0) |
| { |
| /* squash dupes */ |
| struct mx_srv_record *tmp; |
| for (tmp = rec->next; tmp; tmp = tmp->next) |
| if (tmp->offset != 0 && hostname_isequal(rec->target, tmp->target)) |
| tmp->offset = 0; |
| |
| crecp = NULL; |
| while ((crecp = cache_find_by_name(crecp, rec->target, now, F_IPV4 | F_IPV6))) |
| { |
| #ifdef HAVE_IPV6 |
| int type = crecp->flags & F_IPV4 ? T_A : T_AAAA; |
| #else |
| int type = T_A; |
| #endif |
| if (crecp->flags & F_NEG) |
| continue; |
| |
| if (add_resource_record(header, limit, NULL, rec->offset, &ansp, |
| crec_ttl(crecp, now), NULL, type, C_IN, |
| crecp->flags & F_IPV4 ? "4" : "6", &crecp->addr)) |
| addncount++; |
| } |
| } |
| |
| /* done all questions, set up header and return length of result */ |
| /* clear authoritative and truncated flags, set QR flag */ |
| header->hb3 = (header->hb3 & ~(HB3_AA | HB3_TC)) | HB3_QR; |
| /* set RA flag */ |
| header->hb4 |= HB4_RA; |
| |
| /* authoritive - only hosts and DHCP derived names. */ |
| if (auth) |
| header->hb3 |= HB3_AA; |
| |
| /* truncation */ |
| if (trunc) |
| header->hb3 |= HB3_TC; |
| |
| if (anscount == 0 && nxdomain) |
| SET_RCODE(header, NXDOMAIN); |
| else |
| SET_RCODE(header, NOERROR); /* no error */ |
| header->ancount = htons(anscount); |
| header->nscount = htons(0); |
| header->arcount = htons(addncount); |
| return ansp - (unsigned char *)header; |
| } |
| |
| |
| |
| |
| |