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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
//
// A general-purpose Session ID class
#ifndef OPENVPN_COMMON_SESS_ID_H
#define OPENVPN_COMMON_SESS_ID_H
#include <string>
#include <cstring>
#include <cstdint> // for std::uint8_t, std::uint64_t
#include <openvpn/common/exception.hpp>
#include <openvpn/common/size.hpp>
#include <openvpn/common/hash.hpp>
#include <openvpn/common/ostream.hpp>
#include <openvpn/common/base64.hpp>
#include <openvpn/common/arraysize.hpp>
#include <openvpn/buffer/buffer.hpp>
#include <openvpn/random/randapi.hpp>
namespace openvpn {
template <size_t SIZE>
class SessionIDType
{
public:
template <size_t S>
friend class SessionIDType;
// Create a zeroed Sesson ID.
SessionIDType()
{
// compile-time size constraints
static_assert(sizeof(u.data) >= sizeof(std::uint64_t), "SessionIDType SIZE too small");
static_assert(SIZE % sizeof(std::uint64_t) == size_t(0), "SessionIDType SIZE must be an integer multiple of 64 bits");
std::memset(u.data, 0, sizeof(u.data));
}
// Create a random Session ID.
explicit SessionIDType(StrongRandomAPI &rng)
{
rng.rand_bytes(u.data, sizeof(u.data));
}
// Create a Session ID from a base64 (URL-safe) string.
explicit SessionIDType(const std::string &b64)
{
Buffer srcbuf(u.data, sizeof(u.data), false);
try
{
base64_urlsafe->decode(srcbuf, b64);
}
catch (const std::exception &e)
{
throw Exception("SessionID: base64 decode: " + std::string(e.what()));
}
if (srcbuf.size() != sizeof(u.data))
throw Exception("SessionID: wrong input size, actual=" + std::to_string(srcbuf.size()) + " expected=" + std::to_string(sizeof(u.data)));
}
// Create a Session ID from a byte string of size size().
explicit SessionIDType(const std::uint8_t *bytes)
{
std::memcpy(u.data, bytes, SIZE);
}
// Create a Session ID from another Session ID of possibly
// different size. If the other Session ID is larger,
// truncate, if it's smaller, zero our tail.
template <size_t S>
explicit SessionIDType(const SessionIDType<S> &other)
{
for (size_t i = 0; i < array_size(u.dataz); ++i)
u.dataz[i] = (i < array_size(other.u.dataz)) ? other.u.dataz[i] : 0;
}
// Create an encrypted Session ID.
// Intended to be used with TokenEncrypt.
template <typename CRYPT>
explicit SessionIDType(const SessionIDType &other, CRYPT &crypt)
{
crypt(u.data, other.u.data, SIZE);
}
// Session ID is considered to be undefined if all bits are zero.
bool defined() const
{
for (size_t i = 0; i < array_size(u.dataz); ++i)
if (u.dataz[i])
return true;
return false;
}
// Return the lower 64 bits of Session ID regardless of the size.
std::uint64_t shortform() const
{
return u.dataz[0];
}
template <typename HASH>
void hash(HASH &h) const
{
h(u.dataz[0]);
}
// Use a URL-safe base64 encoding.
std::string to_string() const
{
return base64_urlsafe->encode(u.data, sizeof(u.data));
}
bool operator==(const SessionIDType &other) const
{
return std::memcmp(u.data, other.u.data, sizeof(u.data)) == 0;
}
bool operator!=(const SessionIDType &other) const
{
return !operator==(other);
}
bool operator<(const SessionIDType &other) const
{
return std::memcmp(u.data, other.u.data, sizeof(u.data)) < 0;
}
// Weak equality means that the lower 64 bits compare equal.
template <size_t S>
bool eq_weak(const SessionIDType<S> &other) const
{
return shortform() == other.shortform();
}
// True if the string looks like a Session ID.
static bool is(const std::string &str)
{
return base64_urlsafe->is_base64(str, SIZE);
}
static constexpr size_t size()
{
return SIZE;
}
const std::uint8_t *c_data() const
{
return u.data;
}
// Find an element in an unordered map (keyed by Session ID)
// using weak equality. If conflict is true, only return
// element that is present by weak equality, but which is
// not equal to *this by strong equality.
template <typename UNORDERED_MAP>
const SessionIDType *find_weak(const UNORDERED_MAP &m, const bool conflict) const
{
if (m.bucket_count())
{
const size_t bi = m.bucket(*this);
for (auto i = m.cbegin(bi); i != m.cend(bi); ++i)
if (shortform() == i->first.shortform() && (!conflict || *this != i->first))
return &i->first;
}
return nullptr;
}
private:
union {
std::uint64_t dataz[SIZE / sizeof(std::uint64_t)];
std::uint8_t data[SIZE];
} u;
};
// Create two concrete types: 64 and 128-bit Session IDs.
typedef SessionIDType<8> SessionID64;
typedef SessionIDType<16> SessionID128;
OPENVPN_OSTREAM(SessionID64, to_string);
OPENVPN_OSTREAM(SessionID128, to_string);
} // namespace openvpn
OPENVPN_HASH_METHOD(openvpn::SessionID64, shortform);
OPENVPN_HASH_METHOD(openvpn::SessionID128, shortform);
#endif
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