1 /*
2  * This file is part of PowerDNS or dnsdist.
3  * Copyright -- PowerDNS.COM B.V. and its contributors
4  *
5  * This program is free software; you can redistribute it and/or modify
6  * it under the terms of version 2 of the GNU General Public License as
7  * published by the Free Software Foundation.
8  *
9  * In addition, for the avoidance of any doubt, permission is granted to
10  * link this program with OpenSSL and to (re)distribute the binaries
11  * produced as the result of such linking.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
21  */
22 
23 #include "protozero.hh"
24 #include "dnsparser.hh"
25 
encodeComboAddress(const protozero::pbf_tag_type type,const ComboAddress & ca)26 void pdns::ProtoZero::Message::encodeComboAddress(const protozero::pbf_tag_type type, const ComboAddress& ca)
27 {
28   if (ca.sin4.sin_family == AF_INET) {
29     d_message.add_bytes(type, reinterpret_cast<const char*>(&ca.sin4.sin_addr.s_addr), sizeof(ca.sin4.sin_addr.s_addr));
30   }
31   else if (ca.sin4.sin_family == AF_INET6) {
32     d_message.add_bytes(type, reinterpret_cast<const char*>(&ca.sin6.sin6_addr.s6_addr), sizeof(ca.sin6.sin6_addr.s6_addr));
33   }
34 }
35 
encodeNetmask(const protozero::pbf_tag_type type,const Netmask & subnet,uint8_t mask)36 void pdns::ProtoZero::Message::encodeNetmask(const protozero::pbf_tag_type type, const Netmask& subnet, uint8_t mask)
37 {
38   if (!subnet.empty()) {
39     ComboAddress ca(subnet.getNetwork());
40     ca.truncate(mask);
41     if (ca.sin4.sin_family == AF_INET) {
42       d_message.add_bytes(type, reinterpret_cast<const char*>(&ca.sin4.sin_addr.s_addr), sizeof(ca.sin4.sin_addr.s_addr));
43     }
44     else if (ca.sin4.sin_family == AF_INET6) {
45       d_message.add_bytes(type, reinterpret_cast<const char*>(&ca.sin6.sin6_addr.s6_addr), sizeof(ca.sin6.sin6_addr.s6_addr));
46     }
47   }
48 }
49 
encodeDNSName(protozero::pbf_writer & pbf,std::string & buffer,const protozero::pbf_tag_type type,const DNSName & name)50 void pdns::ProtoZero::Message::encodeDNSName(protozero::pbf_writer& pbf, std::string& buffer, const protozero::pbf_tag_type type, const DNSName& name)
51 {
52   // this will append the tag, mark the current position then reserve enough place to write the size
53   protozero::pbf_writer pbf_name{pbf, type};
54   // we append the name to the buffer
55   name.toString(buffer);
56   // leaving the block will cause the sub writer to compute how much was written based on the new size and update the size accordingly
57 }
58 
setRequest(const boost::uuids::uuid & uniqueId,const ComboAddress & requestor,const ComboAddress & local,const DNSName & qname,uint16_t qtype,uint16_t qclass,uint16_t id,bool tcp,size_t len)59 void pdns::ProtoZero::Message::setRequest(const boost::uuids::uuid& uniqueId, const ComboAddress& requestor, const ComboAddress& local, const DNSName& qname, uint16_t qtype, uint16_t qclass, uint16_t id, bool tcp, size_t len)
60 {
61   setMessageIdentity(uniqueId);
62   setSocketFamily(requestor.sin4.sin_family);
63   setSocketProtocol(tcp);
64   setFrom(requestor);
65   setTo(local);
66   setInBytes(len);
67   setTime();
68   setId(id);
69   setQuestion(qname, qtype, qclass);
70   setFromPort(requestor.getPort());
71   setToPort(local.getPort());
72 }
73 
setResponse(const DNSName & qname,uint16_t qtype,uint16_t qclass)74 void pdns::ProtoZero::Message::setResponse(const DNSName& qname, uint16_t qtype, uint16_t qclass)
75 {
76   setType(pdns::ProtoZero::Message::MessageType::DNSResponseType);
77   setQuestion(qname, qtype, qclass);
78 }
79 
addRRsFromPacket(const char * packet,const size_t len,bool includeCNAME)80 void pdns::ProtoZero::Message::addRRsFromPacket(const char* packet, const size_t len, bool includeCNAME)
81 {
82   if (len < sizeof(struct dnsheader)) {
83     return;
84   }
85 
86   const struct dnsheader* dh = reinterpret_cast<const struct dnsheader*>(packet);
87 
88   if (ntohs(dh->ancount) == 0) {
89     return;
90   }
91 
92   if (ntohs(dh->qdcount) == 0) {
93     return;
94   }
95 
96   PacketReader pr(pdns_string_view(packet, len));
97 
98   size_t idx = 0;
99   DNSName rrname;
100   uint16_t qdcount = ntohs(dh->qdcount);
101   uint16_t ancount = ntohs(dh->ancount);
102   uint16_t rrtype;
103   uint16_t rrclass;
104   string blob;
105   struct dnsrecordheader ah;
106 
107   rrname = pr.getName();
108   rrtype = pr.get16BitInt();
109   rrclass = pr.get16BitInt();
110   (void) rrtype;
111   (void) rrclass;
112 
113   /* consume remaining qd if any */
114   if (qdcount > 1) {
115     for(idx = 1; idx < qdcount; idx++) {
116       rrname = pr.getName();
117       rrtype = pr.get16BitInt();
118       rrclass = pr.get16BitInt();
119       (void) rrtype;
120       (void) rrclass;
121     }
122   }
123 
124   /* parse AN */
125   for (idx = 0; idx < ancount; idx++) {
126     rrname = pr.getName();
127     pr.getDnsrecordheader(ah);
128 
129     if (ah.d_type == QType::A || ah.d_type == QType::AAAA) {
130       pr.xfrBlob(blob);
131 
132       addRR(rrname, ah.d_type, ah.d_class, ah.d_ttl, blob);
133 
134     } else if (ah.d_type == QType::CNAME && includeCNAME) {
135       protozero::pbf_writer pbf_rr{d_response, static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::ResponseField::rrs)};
136 
137       encodeDNSName(pbf_rr, d_buffer, static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::name), rrname);
138       pbf_rr.add_uint32(static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::type), ah.d_type);
139       pbf_rr.add_uint32(static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::class_), ah.d_class);
140       pbf_rr.add_uint32(static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::ttl), ah.d_ttl);
141       DNSName target;
142       pr.xfrName(target, true);
143       encodeDNSName(pbf_rr, d_buffer, static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::rdata), target);
144     }
145     else {
146       pr.xfrBlob(blob);
147     }
148   }
149 }
150 
addRR(const DNSName & name,uint16_t uType,uint16_t uClass,uint32_t uTTL,const std::string & blob)151 void pdns::ProtoZero::Message::addRR(const DNSName& name, uint16_t uType, uint16_t uClass, uint32_t uTTL, const std::string& blob)
152 {
153   protozero::pbf_writer pbf_rr{d_response, static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::ResponseField::rrs)};
154   encodeDNSName(pbf_rr, d_buffer, static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::name), name);
155   pbf_rr.add_uint32(static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::type), uType);
156   pbf_rr.add_uint32(static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::class_), uClass);
157   pbf_rr.add_uint32(static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::ttl), uTTL);
158   pbf_rr.add_string(static_cast<protozero::pbf_tag_type>(pdns::ProtoZero::Message::RRField::rdata), blob);
159 }
160