mirror of
https://github.com/OpenVPN/openvpn3.git
synced 2024-09-20 20:13:05 +02:00
84 lines
2.8 KiB
C++
84 lines
2.8 KiB
C++
// OpenVPN -- An application to securely tunnel IP networks
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// over a single port, with support for SSL/TLS-based
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// session authentication and key exchange,
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// packet encryption, packet authentication, and
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// packet compression.
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//
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// Copyright (C) 2012-2020 OpenVPN Inc.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License Version 3
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// as published by the Free Software Foundation.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program in the COPYING file.
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// If not, see <http://www.gnu.org/licenses/>.
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// Atomic file-handling methods.
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#ifndef OPENVPN_COMMON_FILEATOMIC_H
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#define OPENVPN_COMMON_FILEATOMIC_H
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#include <openvpn/common/platform.hpp>
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#if defined(OPENVPN_PLATFORM_WIN)
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#error atomic file methods not supported on Windows
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#endif
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#include <stdio.h> // for rename()
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#include <unistd.h> // for unlink()
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#include <errno.h>
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#include <cstring>
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#include <openvpn/common/file.hpp>
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#include <openvpn/common/hexstr.hpp>
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#include <openvpn/common/fileunix.hpp>
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#include <openvpn/common/path.hpp>
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#include <openvpn/common/strerror.hpp>
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#include <openvpn/random/randapi.hpp>
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namespace openvpn {
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// Atomically write binary buffer to file (relies on
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// the atomicity of rename())
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inline void write_binary_atomic(const std::string& fn,
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const std::string& tmpdir,
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const mode_t mode,
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const std::uint64_t mtime_ns, // set explicit modification-time in nanoseconds since epoch, or 0 to defer to system
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const ConstBuffer& buf,
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RandomAPI& rng)
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{
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// generate temporary filename
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unsigned char data[16];
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rng.rand_fill(data);
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const std::string tfn = path::join(tmpdir, '.' + path::basename(fn).substr(0, 64) + '.' + render_hex(data, sizeof(data)));
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// write to temporary file
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write_binary_unix(tfn, mode, mtime_ns, buf);
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// then move into position
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if (::rename(tfn.c_str(), fn.c_str()) == -1)
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{
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const int eno = errno;
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::unlink(tfn.c_str()); // move failed, so delete the temporary file
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OPENVPN_THROW(file_unix_error, "error moving '" << tfn << "' -> '" << fn << "' : " << strerror_str(eno));
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}
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}
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inline void write_binary_atomic(const std::string& fn,
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const std::string& tmpdir,
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const mode_t mode,
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const std::uint64_t mtime_ns,
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const Buffer& buf,
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RandomAPI& rng)
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{
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return write_binary_atomic(fn, tmpdir, mode, mtime_ns, const_buffer_ref(buf), rng);
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}
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}
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#endif
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