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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) 2012- OpenVPN Inc.
//
// SPDX-License-Identifier: MPL-2.0 OR AGPL-3.0-only WITH openvpn3-openssl-exception
//
// Encapsulate the state of a static or dynamic authentication challenge.
#ifndef OPENVPN_AUTH_CR_H
#define OPENVPN_AUTH_CR_H
#include <string>
#include <sstream>
#include <vector>
#include <openvpn/common/exception.hpp>
#include <openvpn/common/base64.hpp>
#include <openvpn/common/split.hpp>
#include <openvpn/common/rc.hpp>
#include <openvpn/common/string.hpp>
// Static Challenge response:
// SCRV1:<BASE64_PASSWORD>:<BASE64_RESPONSE>
//
// Dynamic Challenge:
// CRV1:<FLAGS>:<STATE_ID>:<BASE64_USERNAME>:<CHALLENGE_TEXT>
// FLAGS is a comma-separated list of options:
// E -- echo
// R -- response required
//
// Dynamic Challenge response:
// Username: [username decoded from username_base64]
// Password: CRV1::<STATE_ID>::<RESPONSE_TEXT>
namespace openvpn {
class ChallengeResponse : public RC<thread_unsafe_refcount>
{
public:
typedef RCPtr<ChallengeResponse> Ptr;
OPENVPN_SIMPLE_EXCEPTION(dynamic_challenge_parse_error);
OPENVPN_SIMPLE_EXCEPTION(static_challenge_parse_error);
ChallengeResponse()
: echo(false), response_required(false)
{
}
explicit ChallengeResponse(const std::string &cookie)
: echo(false), response_required(false)
{
init(cookie);
}
ChallengeResponse(const std::string &cookie, const std::string &user)
: echo(false), response_required(false)
{
if (!is_dynamic(cookie) && cookie.find_first_of(':') == std::string::npos)
{
state_id = cookie;
username = user;
}
else
init(cookie);
}
void init(const std::string &cookie)
{
typedef std::vector<std::string> StringList;
StringList sl;
sl.reserve(5);
Split::by_char_void<StringList, NullLex, Split::NullLimit>(sl, cookie, ':', 0, 4);
if (sl.size() != 5)
throw dynamic_challenge_parse_error();
if (sl[0] != "CRV1")
throw dynamic_challenge_parse_error();
// parse options
{
StringList opt;
opt.reserve(2);
Split::by_char_void<StringList, NullLex, Split::NullLimit>(opt, sl[1], ',');
for (StringList::const_iterator i = opt.begin(); i != opt.end(); ++i)
{
if (*i == "E")
echo = true;
else if (*i == "R")
response_required = true;
}
}
// save state ID
state_id = sl[2];
// save username
try
{
username = base64->decode(sl[3]);
}
catch (const Base64::base64_decode_error &)
{
throw dynamic_challenge_parse_error();
}
// save challenge
challenge_text = sl[4];
}
static bool is_dynamic(const std::string &s)
{
return string::starts_with(s, "CRV1:");
}
static bool is_static(const std::string &s)
{
return string::starts_with(s, "SCRV1:");
}
static void validate_dynamic(const std::string &cookie)
{
ChallengeResponse cr(cookie);
}
std::string construct_dynamic_password(const std::string &response) const
{
std::ostringstream os;
os << "CRV1::" << state_id << "::" << response;
return os.str();
}
static std::string construct_static_password(const std::string &password,
const std::string &response)
{
std::ostringstream os;
os << "SCRV1:" << base64->encode(password) << ':' << base64->encode(response);
return os.str();
}
static void parse_static_cookie(const std::string &cookie,
std::string &password,
std::string &response)
{
typedef std::vector<std::string> StringList;
StringList sl;
sl.reserve(3);
Split::by_char_void<StringList, NullLex, Split::NullLimit>(sl, cookie, ':');
if (sl.size() != 3)
throw static_challenge_parse_error();
if (sl[0] != "SCRV1")
throw static_challenge_parse_error();
// get password
try
{
password = base64->decode(sl[1]);
}
catch (const Base64::base64_decode_error &)
{
throw static_challenge_parse_error();
}
// get response
try
{
response = base64->decode(sl[2]);
}
catch (const Base64::base64_decode_error &)
{
throw static_challenge_parse_error();
}
}
static std::string generate_dynamic_challenge(const std::string &session_token,
const std::string &username,
const std::string &challenge,
const bool echo,
const bool response_required)
{
std::ostringstream os;
bool comma = false;
os << "CRV1:";
if (echo)
{
if (comma)
os << ",";
os << "E";
comma = true;
}
if (response_required)
{
if (comma)
os << ",";
os << "R";
comma = true;
}
os << ':' << session_token;
os << ':' << base64->encode(username);
os << ':' << challenge;
return os.str();
}
const std::string &get_state_id() const
{
return state_id;
}
const std::string &get_username() const
{
return username;
}
bool get_echo() const
{
return echo;
}
bool get_response_required() const
{
return response_required;
}
const std::string &get_challenge_text() const
{
return challenge_text;
}
private:
bool echo;
bool response_required;
std::string state_id;
std::string username;
std::string challenge_text;
};
} // namespace openvpn
#endif
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