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// OpenVPN -- An application to securely tunnel IP networks
// over a single port, with support for SSL/TLS-based
// session authentication and key exchange,
// packet encryption, packet authentication, and
// packet compression.
//
// Copyright (C) 2022- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
#pragma once
#include <vector>
#include <cstdint>
#include <algorithm>
#include <sstream>
#include <openvpn/options/continuation.hpp>
#include <openvpn/client/dns_options.hpp>
#ifdef HAVE_JSON
#include <openvpn/common/jsonhelper.hpp>
#endif
namespace openvpn {
/**
* @class DnsOptions
* @brief All DNS options set with the --dns or --dhcp-option directive
*/
struct DnsOptionsParser : public DnsOptions
{
DnsOptionsParser(const OptionList &opt, bool use_dhcp_search_domains_as_split_domains)
{
parse_dns_options(opt);
parse_dhcp_options(opt, use_dhcp_search_domains_as_split_domains, !servers.empty());
if (!parse_errors.empty())
{
OPENVPN_THROW_ARG1(option_error, ERR_INVALID_OPTION_DNS, parse_errors);
}
}
static int parse_priority(const std::string &prio_str)
{
const auto min_prio = std::numeric_limits<std::int8_t>::min();
const auto max_prio = std::numeric_limits<std::int8_t>::max();
int priority;
if (!parse_number_validate<int>(prio_str, 4, min_prio, max_prio, &priority))
OPENVPN_THROW_ARG1(option_error, ERR_INVALID_OPTION_DNS, "dns server priority '" << prio_str << "' invalid");
return priority;
}
protected:
std::string parse_errors;
void parse_dns_options(const OptionList &opt)
{
auto indices = opt.get_index_ptr("dns");
if (indices == nullptr)
{
return;
}
for (const auto i : *indices)
{
try
{
const auto &o = opt[i];
if (o.size() >= 3 && o.ref(1) == "search-domains")
{
for (std::size_t j = 2; j < o.size(); j++)
{
search_domains.emplace_back(o.ref(j));
}
}
else if (o.size() >= 5 && o.ref(1) == "server")
{
auto priority = parse_priority(o.ref(2));
auto &server = get_server(priority);
const auto &server_suboption = o.ref(3);
if (server_suboption == "address" && o.size() <= 12)
{
for (std::size_t j = 4; j < o.size(); j++)
{
try
{
server.addresses.emplace_back(DnsAddress(o.ref(j)));
}
catch (const openvpn::Exception &error)
{
OPENVPN_THROW_ARG1(option_error,
ERR_INVALID_OPTION_DNS,
"dns server " << priority << " error: " << error.what());
}
}
}
else if (server_suboption == "resolve-domains")
{
for (std::size_t j = 4; j < o.size(); j++)
{
server.domains.emplace_back(o.ref(j));
}
}
else if (server_suboption == "dnssec" && o.size() == 5)
{
try
{
server.parse_dnssec_value(o.ref(4));
}
catch (const openvpn::Exception &error)
{
OPENVPN_THROW_ARG1(option_error,
ERR_INVALID_OPTION_DNS,
"dns server " << priority << " error: " << error.what());
}
}
else if (server_suboption == "transport" && o.size() == 5)
{
try
{
server.parse_transport_value(o.ref(4));
}
catch (const openvpn::Exception &error)
{
OPENVPN_THROW_ARG1(option_error, ERR_INVALID_OPTION_DNS, "dns server " << priority << " error: " << error.what());
}
}
else if (server_suboption == "sni" && o.size() == 5)
{
server.sni = o.ref(4);
}
else
{
OPENVPN_THROW_ARG1(option_error, ERR_INVALID_OPTION_DNS, "dns server " << priority << " option '" << server_suboption << "' unknown or too many parameters");
}
}
else
{
OPENVPN_THROW_ARG1(option_error, ERR_INVALID_OPTION_DNS, "dns option unknown or invalid number of parameters " << o.render(Option::RENDER_TRUNC_64 | Option::RENDER_BRACKET));
}
}
catch (const std::exception &e)
{
parse_errors += "\n";
parse_errors += e.what();
}
}
// Check and remove servers without an address
std::vector<int> remove_servers;
for (const auto &[priority, server] : servers)
{
if (server.addresses.empty())
{
parse_errors += "\n";
parse_errors += "dns server " + std::to_string(priority) + " does not have an address assigned";
remove_servers.push_back(priority);
}
}
for (const auto &prio : remove_servers)
{
servers.erase(prio);
}
// Clear search domains when no servers were configured
if (servers.empty())
{
search_domains.clear();
}
}
void parse_dhcp_options(const OptionList &opt, bool use_search_as_split_domains, bool ignore_values)
{
auto dhcp_map = opt.map().find("dhcp-option");
if (dhcp_map == opt.map().end())
{
return;
}
// Example:
// [dhcp-option] [DNS] [172.16.0.23]
// [dhcp-option] [DOMAIN] [openvpn.net]
// [dhcp-option] [DOMAIN] [example.com]
// [dhcp-option] [DOMAIN] [foo1.com foo2.com foo3.com ...]
// [dhcp-option] [DOMAIN] [bar1.com] [bar2.com] [bar3.com] ...
// [dhcp-option] [ADAPTER_DOMAIN_SUFFIX] [mycompany.com]
std::string adapter_domain_suffix;
for (const auto &i : dhcp_map->second)
{
try
{
const Option &o = opt[i];
const std::string &type = o.get(1, 64);
if (type == "DNS" || type == "DNS6")
{
o.exact_args(3);
try
{
if (!ignore_values)
{
auto &server = get_server(0);
server.addresses.emplace_back(DnsAddress(o.get(2, 256)));
from_dhcp_options = true;
}
}
catch (const IP::ip_exception &)
{
OPENVPN_THROW_ARG1(option_error, ERR_INVALID_OPTION_DNS, o.render(Option::RENDER_BRACKET) << " invalid address");
}
catch (const openvpn::Exception &error)
{
OPENVPN_THROW_ARG1(option_error,
ERR_INVALID_OPTION_DNS,
o.render(Option::RENDER_BRACKET) << "dhcp-option DNS error: " << error.what());
}
}
else if (type == "DOMAIN" || type == "DOMAIN-SEARCH")
{
o.min_args(3);
for (size_t i = 2; i < o.size(); ++i)
{
using StrVec = std::vector<std::string>;
StrVec domains = Split::by_space<StrVec, StandardLex, SpaceMatch, Split::NullLimit>(o.get(i, 256));
if (ignore_values)
{
continue;
}
for (const auto &domain : domains)
{
from_dhcp_options = true;
if (use_search_as_split_domains)
{
auto &server = get_server(0);
server.domains.emplace_back(domain);
}
else
{
search_domains.emplace_back(domain);
}
}
}
}
else if (type == "ADAPTER_DOMAIN_SUFFIX")
{
o.exact_args(3);
if (!ignore_values)
{
adapter_domain_suffix = o.ref(2);
from_dhcp_options = true;
}
}
}
catch (const std::exception &e)
{
parse_errors += "\n";
parse_errors += e.what();
}
}
if (!adapter_domain_suffix.empty())
{
search_domains.insert(search_domains.begin(), DnsDomain(std::move(adapter_domain_suffix)));
}
if (!ignore_values && servers.size() && servers[0].addresses.empty())
{
parse_errors += "\n";
parse_errors += "dns server does not have an address assigned";
servers.clear();
}
}
};
struct DnsOptionsMerger : public PushOptionsMerger
{
using PriorityList = std::vector<std::int8_t>;
struct DnsFilter : public OptionList::FilterBase
{
DnsFilter(PriorityList &&pushed_prios)
: pushed_prios_(std::forward<PriorityList>(pushed_prios))
{
}
bool filter(const Option &opt) override
{
if (opt.empty()
|| opt.size() < 3
|| opt.ref(0) != "dns"
|| opt.ref(1) != "server")
{
return true;
}
const auto priority = DnsOptionsParser::parse_priority(opt.ref(2));
const auto it = std::find(pushed_prios_.begin(), pushed_prios_.end(), priority);
// Filter out server option if an option with this priority was pushed
return it == pushed_prios_.end() ? true : false;
}
protected:
const PriorityList pushed_prios_;
};
void merge(OptionList &pushed, const OptionList &config) const override
{
PriorityList pushed_prios;
auto indices = pushed.get_index_ptr("dns");
if (indices)
{
for (const auto i : *indices)
{
if (pushed[i].size() < 3 || pushed[i].ref(1) != "server")
continue;
const auto priority = DnsOptionsParser::parse_priority(pushed[i].ref(2));
pushed_prios.emplace_back(priority);
}
}
DnsFilter filter(std::move(pushed_prios));
pushed.extend(config, &filter);
}
};
} // namespace openvpn
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