// Copyright (c) 2014-2018, The Monero Project
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#pragma once
#include <vector>
#include <string>
#include <functional>
#include <boost/optional/optional_fwd.hpp>
namespace tools
{
// RFC defines for record types and classes for DNS, gleaned from ldns source
const static int DNS_CLASS_IN = 1;
const static int DNS_TYPE_A = 1;
const static int DNS_TYPE_TXT = 16;
const static int DNS_TYPE_AAAA = 8;
struct DNSResolverData;
/**
* @brief Provides high-level access to DNS resolution
*
* This class is designed to provide a high-level abstraction to DNS resolution
* functionality, including access to TXT records and such. It will also
* handle DNSSEC validation of the results.
*/
class DNSResolver
{
private:
/**
* @brief Constructs an instance of DNSResolver
*
* Constructs a class instance and does setup stuff for the backend resolver.
*/
DNSResolver();
public:
/**
* @brief takes care of freeing C pointers and such
*/
~DNSResolver();
/**
* @brief gets ipv4 addresses from DNS query of a URL
*
* returns a vector of all IPv4 "A" records for given URL.
* If no "A" records found, returns an empty vector.
*
* @param url A string containing a URL to query for
*
* @param dnssec_available
*
* @return vector of strings containing ipv4 addresses
*/
std::vector<std::string> get_ipv4(const std::string& url, bool& dnssec_available, bool& dnssec_valid);
/**
* @brief gets ipv6 addresses from DNS query
*
* returns a vector of all IPv6 "A" records for given URL.
* If no "A" records found, returns an empty vector.
*
* @param url A string containing a URL to query for
*
* @return vector of strings containing ipv6 addresses
*/
std::vector<std::string> get_ipv6(const std::string& url, bool& dnssec_available, bool& dnssec_valid);
/**
* @brief gets all TXT records from a DNS query for the supplied URL;
* if no TXT record present returns an empty vector.
*
* @param url A string containing a URL to query for
*
* @return A vector of strings containing a TXT record; or an empty vector
*/
// TODO: modify this to accommodate DNSSEC
std::vector<std::string> get_txt_record(const std::string& url, bool& dnssec_available, bool& dnssec_valid);
/**
* @brief Gets a DNS address from OpenAlias format
*
* If the address looks good, but contains one @ symbol, replace that with a .
* e.g. donate@getmonero.org becomes donate.getmonero.org
*
* @param oa_addr OpenAlias address
*
* @return dns_addr DNS address
*/
std::string get_dns_format_from_oa_address(const std::string& oa_addr);
/**
* @brief Gets the singleton instance of DNSResolver
*
* @return returns a pointer to the singleton
*/
static DNSResolver& instance();
/**
* @brief Gets a new instance of DNSResolver
*
* @return returns a pointer to the new object
*/
static DNSResolver create();
private:
/**
* @brief gets all records of a given type from a DNS query for the supplied URL;
* if no such record is present returns an empty vector.
*
* @param url A string containing a URL to query for
* @param record_type the record type to retrieve (DNS_TYPE_A, etc)
* @param reader a function that converts a record data to a string
*
* @return A vector of strings containing the requested record; or an empty vector
*/
// TODO: modify this to accommodate DNSSEC
std::vector<std::string> get_record(const std::string& url, int record_type, boost::optional<std::string> (*reader)(const char *,size_t), bool& dnssec_available, bool& dnssec_valid);
/**
* @brief Checks a string to see if it looks like a URL
*
* @param addr the string to be checked
*
* @return true if it looks enough like a URL, false if not
*/
bool check_address_syntax(const char *addr) const;
DNSResolverData *m_data;
}; // class DNSResolver
namespace dns_utils
{
std::string address_from_txt_record(const std::string& s);
std::vector<std::string> addresses_from_url(const std::string& url, bool& dnssec_valid);
std::string get_account_address_as_str_from_url(const std::string& url, bool& dnssec_valid, std::function<std::string(const std::string&, const std::vector<std::string>&, bool)> confirm_dns);
bool load_txt_records_from_dns(std::vector<std::string> &records, const std::vector<std::string> &dns_urls);
std::vector<std::string> parse_dns_public(const char *s);
} // namespace tools::dns_utils
} // namespace tools
