transmission/libtransmission/session-id.c

211 lines
5.3 KiB
C

/*
* This file Copyright (C) 2016 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#include <string.h>
#include <time.h>
#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"
#define SESSION_ID_SIZE 48
#define SESSION_ID_DURATION_SEC (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 (void)
{
const char pool[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
const size_t pool_size = sizeof (pool) - 1;
char * buf = tr_new (char, SESSION_ID_SIZE + 1);
tr_rand_buffer (buf, SESSION_ID_SIZE);
for (size_t i = 0; i < SESSION_ID_SIZE; ++i)
buf[i] = pool[(unsigned char) buf[i] % pool_size];
buf[SESSION_ID_SIZE] = '\0';
return buf;
}
static char *
get_session_id_lock_file_path (const char * session_id)
{
char * lock_file_dir = tr_getSessionIdDir ();
char * lock_file_path = tr_strdup_printf ("%s/tr_session_id_%s", lock_file_dir, session_id);
tr_free (lock_file_dir);
return lock_file_path;
}
static tr_sys_file_t
create_session_id_lock_file (const char * session_id)
{
if (session_id == NULL)
return TR_BAD_SYS_FILE;
char * lock_file_path = get_session_id_lock_file_path (session_id);
tr_sys_file_t lock_file;
tr_error * error = NULL;
lock_file = tr_sys_file_open (lock_file_path, 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, NULL);
lock_file = TR_BAD_SYS_FILE;
}
}
if (error != NULL)
{
tr_logAddError ("Unable to create session lock file (%d): %s", error->code, error->message);
tr_error_free (error);
}
tr_free (lock_file_path);
return lock_file;
}
static void
destroy_session_id_lock_file (tr_sys_file_t lock_file,
const char * session_id)
{
if (lock_file != TR_BAD_SYS_FILE)
tr_sys_file_close (lock_file, NULL);
if (session_id != NULL)
{
char * lock_file_path = get_session_id_lock_file_path (session_id);
tr_sys_path_remove (lock_file_path, NULL);
tr_free (lock_file_path);
}
}
tr_session_id_t
tr_session_id_new (void)
{
const tr_session_id_t 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 == NULL)
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);
}
const char *
tr_session_id_get_current (tr_session_id_t session_id)
{
const time_t now = tr_time ();
if (session_id->current_value == NULL || 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 + SESSION_ID_DURATION_SEC;
}
return session_id->current_value;
}
bool
tr_session_id_is_local (const char * session_id)
{
bool ret = false;
if (session_id != NULL)
{
char * lock_file_path = get_session_id_lock_file_path (session_id);
tr_sys_file_t lock_file;
tr_error * error = NULL;
lock_file = tr_sys_file_open (lock_file_path, 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
if (error->code == EWOULDBLOCK)
#else
if (error->code == ERROR_LOCK_VIOLATION)
#endif
{
ret = true;
tr_error_clear (&error);
}
}
tr_sys_file_close (lock_file, NULL);
}
if (error != NULL)
{
tr_logAddError ("Unable to open session lock file (%d): %s", error->code, error->message);
tr_error_free (error);
}
tr_free (lock_file_path);
}
return ret;
}