transmission/libtransmission/session-id.cc

204 lines
5.3 KiB
C++

// This file Copyright © 2016-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <ctime>
#include <string_view>
#ifndef _WIN32
#include <sys/stat.h>
#endif
#include "transmission.h"
#include "crypto-utils.h"
#include "error.h"
#include "error-types.h"
#include "file.h"
#include "log.h"
#include "platform.h"
#include "session-id.h"
#include "utils.h"
using namespace std::literals;
static auto constexpr SessionIdSize = size_t{ 48 };
static auto constexpr SessionIdDurationSec = time_t{ 60 * 60 }; /* expire in an hour */
struct tr_session_id
{
char* current_value;
char* previous_value;
tr_sys_file_t current_lock_file;
tr_sys_file_t previous_lock_file;
time_t expires_at;
};
static char* generate_new_session_id_value()
{
char const pool[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
size_t const pool_size = sizeof(pool) - 1;
auto* buf = tr_new(char, SessionIdSize + 1);
tr_rand_buffer(buf, SessionIdSize);
for (size_t i = 0; i < SessionIdSize; ++i)
{
buf[i] = pool[(unsigned char)buf[i] % pool_size];
}
buf[SessionIdSize] = '\0';
return buf;
}
static std::string get_session_id_lock_file_path(std::string_view session_id)
{
return tr_strvJoin(tr_getSessionIdDir(), TR_PATH_DELIMITER_STR, "tr_session_id_"sv, session_id);
}
static tr_sys_file_t create_session_id_lock_file(char const* session_id)
{
if (session_id == nullptr)
{
return TR_BAD_SYS_FILE;
}
auto const lock_file_path = get_session_id_lock_file_path(session_id);
tr_error* error = nullptr;
auto lock_file = tr_sys_file_open(
lock_file_path.c_str(),
TR_SYS_FILE_READ | TR_SYS_FILE_WRITE | TR_SYS_FILE_CREATE,
0600,
&error);
if (lock_file != TR_BAD_SYS_FILE)
{
if (tr_sys_file_lock(lock_file, TR_SYS_FILE_LOCK_EX | TR_SYS_FILE_LOCK_NB, &error))
{
#ifndef _WIN32
/* Allow any user to lock the file regardless of current umask */
fchmod(lock_file, 0644);
#endif
}
else
{
tr_sys_file_close(lock_file, nullptr);
lock_file = TR_BAD_SYS_FILE;
}
}
if (error != nullptr)
{
tr_logAddError("Unable to create session lock file (%d): %s", error->code, error->message);
tr_error_free(error);
}
return lock_file;
}
static void destroy_session_id_lock_file(tr_sys_file_t lock_file, char const* session_id)
{
if (lock_file != TR_BAD_SYS_FILE)
{
tr_sys_file_close(lock_file, nullptr);
}
if (session_id != nullptr)
{
auto const lock_file_path = get_session_id_lock_file_path(session_id);
tr_sys_path_remove(lock_file_path.c_str(), nullptr);
}
}
tr_session_id_t tr_session_id_new()
{
auto const session_id = tr_new0(struct tr_session_id, 1);
session_id->current_lock_file = TR_BAD_SYS_FILE;
session_id->previous_lock_file = TR_BAD_SYS_FILE;
return session_id;
}
void tr_session_id_free(tr_session_id_t session_id)
{
if (session_id == nullptr)
{
return;
}
destroy_session_id_lock_file(session_id->previous_lock_file, session_id->previous_value);
destroy_session_id_lock_file(session_id->current_lock_file, session_id->current_value);
tr_free(session_id->previous_value);
tr_free(session_id->current_value);
tr_free(session_id);
}
char const* tr_session_id_get_current(tr_session_id_t session_id)
{
time_t const now = tr_time();
if (session_id->current_value == nullptr || now >= session_id->expires_at)
{
destroy_session_id_lock_file(session_id->previous_lock_file, session_id->previous_value);
tr_free(session_id->previous_value);
session_id->previous_value = session_id->current_value;
session_id->current_value = generate_new_session_id_value();
session_id->previous_lock_file = session_id->current_lock_file;
session_id->current_lock_file = create_session_id_lock_file(session_id->current_value);
session_id->expires_at = now + SessionIdDurationSec;
}
return session_id->current_value;
}
bool tr_session_id_is_local(char const* session_id)
{
bool ret = false;
if (session_id != nullptr)
{
auto const lock_file_path = get_session_id_lock_file_path(session_id);
tr_error* error = nullptr;
auto lock_file = tr_sys_file_open(lock_file_path.c_str(), TR_SYS_FILE_READ, 0, &error);
if (lock_file == TR_BAD_SYS_FILE)
{
if (TR_ERROR_IS_ENOENT(error->code))
{
tr_error_clear(&error);
}
}
else
{
if (!tr_sys_file_lock(lock_file, TR_SYS_FILE_LOCK_SH | TR_SYS_FILE_LOCK_NB, &error) &&
#ifndef _WIN32
(error->code == EWOULDBLOCK))
#else
(error->code == ERROR_LOCK_VIOLATION))
#endif
{
ret = true;
tr_error_clear(&error);
}
tr_sys_file_close(lock_file, nullptr);
}
if (error != nullptr)
{
tr_logAddError("Unable to open session lock file (%d): %s", error->code, error->message);
tr_error_free(error);
}
}
return ret;
}