| /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */ |
| /** |
| * Copyright (c) 2014-2015, Regents of the University of California, |
| * Arizona Board of Regents, |
| * Colorado State University, |
| * University Pierre & Marie Curie, Sorbonne University, |
| * Washington University in St. Louis, |
| * Beijing Institute of Technology, |
| * The University of Memphis. |
| * |
| * This file is part of NFD (Named Data Networking Forwarding Daemon). |
| * See AUTHORS.md for complete list of NFD authors and contributors. |
| * |
| * NFD 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, |
| * either version 3 of the License, or (at your option) any later version. |
| * |
| * NFD 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 |
| * NFD, e.g., in COPYING.md file. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include "base-dns.hpp" |
| |
| #include <sys/types.h> |
| #include <netinet/in.h> |
| #include <resolv.h> |
| #include <arpa/nameser.h> |
| |
| #ifdef __APPLE__ |
| #include <arpa/nameser_compat.h> |
| #endif |
| |
| namespace ndn { |
| namespace tools { |
| namespace autoconfig { |
| |
| union BaseDns::QueryAnswer |
| { |
| HEADER header; |
| uint8_t buf[NS_PACKETSZ]; |
| }; |
| |
| BaseDns::BaseDns(Face& face, KeyChain& keyChain, const NextStageCallback& nextStageOnFailure) |
| : Base(face, keyChain, nextStageOnFailure) |
| { |
| } |
| |
| std::string |
| BaseDns::querySrvRr(const std::string& fqdn) |
| { |
| std::string srvDomain = "_ndn._udp." + fqdn; |
| std::cerr << "Sending DNS query for SRV record for " << srvDomain << std::endl; |
| |
| QueryAnswer queryAnswer; |
| int answerSize = res_query(srvDomain.c_str(), |
| ns_c_in, |
| ns_t_srv, |
| queryAnswer.buf, |
| sizeof(queryAnswer)); |
| if (answerSize == 0) { |
| throw Error("No DNS SRV records found for " + srvDomain); |
| } |
| return parseSrvRr(queryAnswer, answerSize); |
| } |
| |
| /** |
| * @brief Send DNS SRV request using search domain list |
| */ |
| std::string |
| BaseDns::querySrvRrSearch() |
| { |
| std::cerr << "Sending DNS query for SRV record for _ndn._udp" << std::endl; |
| |
| QueryAnswer queryAnswer; |
| |
| _res.retry = 2; |
| _res.ndots = 10; |
| |
| int answerSize = res_search("_ndn._udp", |
| ns_c_in, |
| ns_t_srv, |
| queryAnswer.buf, |
| sizeof(queryAnswer)); |
| |
| if (answerSize == 0) { |
| throw Error("No DNS SRV records found for _ndn._udp"); |
| } |
| |
| return parseSrvRr(queryAnswer, answerSize); |
| } |
| |
| std::string |
| BaseDns::parseSrvRr(const QueryAnswer& queryAnswer, int answerSize) |
| { |
| // The references of the next classes are: |
| // http://www.diablotin.com/librairie/networking/dnsbind/ch14_02.htm |
| |
| struct rechdr |
| { |
| uint16_t type; |
| uint16_t iclass; |
| uint32_t ttl; |
| uint16_t length; |
| }; |
| |
| struct srv_t |
| { |
| uint16_t priority; |
| uint16_t weight; |
| uint16_t port; |
| uint8_t* target; |
| }; |
| |
| if (ntohs(queryAnswer.header.ancount) == 0) { |
| throw Error("SRV record cannot be parsed"); |
| } |
| |
| const uint8_t* blob = queryAnswer.buf + NS_HFIXEDSZ; |
| |
| blob += dn_skipname(blob, queryAnswer.buf + answerSize) + NS_QFIXEDSZ; |
| |
| char srvName[NS_MAXDNAME]; |
| int serverNameSize = dn_expand(queryAnswer.buf, // message pointer |
| queryAnswer.buf + answerSize, // end of message |
| blob, // compressed server name |
| srvName, // expanded server name |
| NS_MAXDNAME); |
| if (serverNameSize <= 0) { |
| throw Error("SRV record cannot be parsed (error decoding domain name)"); |
| } |
| |
| const srv_t* server = reinterpret_cast<const srv_t*>(&blob[sizeof(rechdr)]); |
| uint16_t convertedPort = be16toh(server->port); |
| |
| blob += serverNameSize + NS_HFIXEDSZ + NS_QFIXEDSZ; |
| |
| char hostName[NS_MAXDNAME]; |
| int hostNameSize = dn_expand(queryAnswer.buf, // message pointer |
| queryAnswer.buf + answerSize, // end of message |
| blob, // compressed host name |
| hostName, // expanded host name |
| NS_MAXDNAME); |
| if (hostNameSize <= 0) { |
| throw Error("SRV record cannot be parsed (error decoding host name)"); |
| } |
| |
| std::string uri = "udp://"; |
| uri.append(hostName); |
| uri.append(":"); |
| uri.append(std::to_string(convertedPort)); |
| |
| return uri; |
| } |
| |
| } // namespace autoconfig |
| } // namespace tools |
| } // namespace ndn |