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/*
* Copyright (C) 2015, 2016, 2017 "IoT.bzh"
* Author "Fulup Ar Foll"
* Author: José Bollo <jose.bollo@iot.bzh>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <time.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <uuid/uuid.h>
#include <assert.h>
#include <errno.h>
#include <json-c/json.h>
#include "afb-session.h"
#include "verbose.h"
#define SIZEUUID 37
#define HEADCOUNT 16
#define COOKIECOUNT 8
#define COOKIEMASK (COOKIECOUNT - 1)
#define _MAXEXP_ ((time_t)(~(time_t)0))
#define _MAXEXP2_ ((time_t)((((unsigned long long)_MAXEXP_) >> 1)))
#define MAX_EXPIRATION (_MAXEXP_ >= 0 ? _MAXEXP_ : _MAXEXP2_)
#define NOW (time(NULL))
struct cookie
{
struct cookie *next;
const void *key;
void *value;
void (*freecb)(void*);
};
struct afb_session
{
struct afb_session *next; /* link to the next */
unsigned refcount;
int timeout;
time_t expiration; // expiration time of the token
pthread_mutex_t mutex;
struct cookie *cookies[COOKIECOUNT];
char autoclose;
char idx;
char uuid[SIZEUUID]; // long term authentication of remote client
char token[SIZEUUID]; // short term authentication of remote client
};
// Session UUID are store in a simple array [for 10 sessions this should be enough]
static struct {
pthread_mutex_t mutex; // declare a mutex to protect hash table
struct afb_session *heads[HEADCOUNT]; // sessions
int count; // current number of sessions
int max;
int timeout;
char initok[SIZEUUID];
} sessions;
/* generate a uuid */
static void new_uuid(char uuid[SIZEUUID])
{
uuid_t newuuid;
uuid_generate(newuuid);
uuid_unparse_lower(newuuid, uuid);
}
static inline void lock(struct afb_session *session)
{
pthread_mutex_lock(&session->mutex);
}
static inline void unlock(struct afb_session *session)
{
pthread_mutex_unlock(&session->mutex);
}
// Free context [XXXX Should be protected again memory abort XXXX]
static void close_session(struct afb_session *session)
{
int idx;
struct cookie *cookie;
/* free cookies */
for (idx = 0 ; idx < COOKIECOUNT ; idx++) {
while ((cookie = session->cookies[idx])) {
session->cookies[idx] = cookie->next;
if (cookie->freecb != NULL)
cookie->freecb(cookie->value);
free(cookie);
}
}
}
/* tiny hash function inspired from pearson */
static int pearson4(const char *text)
{
static uint8_t T[16] = {
4, 1, 6, 0, 9, 14, 11, 5,
2, 3, 12, 15, 10, 7, 8, 13
};
uint8_t r, c;
for (r = 0; (c = (uint8_t)*text) ; text++) {
r = T[r ^ (15 & c)];
r = T[r ^ (c >> 4)];
}
return r; // % HEADCOUNT;
}
/**
* Initialize the session manager with a 'max_session_count',
* an initial common 'timeout' and an initial common token 'initok'.
*
* @param max_session_count maximum allowed session count in the same time
* @param timeout the initial default timeout of sessions
* @param initok the initial default token of sessions
*
*/
int afb_session_init (int max_session_count, int timeout, const char *initok)
{
pthread_mutex_init(&sessions.mutex, NULL);
sessions.max = max_session_count;
sessions.timeout = timeout;
if (initok == NULL)
/* without token, a secret is made to forbid creation of sessions */
new_uuid(sessions.initok);
else if (strlen(initok) < sizeof sessions.initok)
strcpy(sessions.initok, initok);
else {
ERROR("initial token '%s' too long (max length %d)", initok, ((int)(sizeof sessions.initok)) - 1);
errno = EINVAL;
return -1;
}
return 0;
}
const char *afb_session_initial_token()
{
return sessions.initok;
}
static struct afb_session *search (const char* uuid, int idx)
{
struct afb_session *session;
session = sessions.heads[idx];
while (session && strcmp(uuid, session->uuid))
session = session->next;
return session;
}
static void destroy (struct afb_session *session)
{
struct afb_session **prv;
assert (session != NULL);
close_session(session);
pthread_mutex_lock(&sessions.mutex);
prv = &sessions.heads[(int)session->idx];
while (*prv)
if (*prv != session)
prv = &((*prv)->next);
else {
*prv = session->next;
sessions.count--;
pthread_mutex_destroy(&session->mutex);
free(session);
break;
}
pthread_mutex_unlock(&sessions.mutex);
}
// Loop on every entry and remove old context sessions.hash
static time_t cleanup ()
{
struct afb_session *session, *next;
int idx;
time_t now;
// Loop on Sessions Table and remove anything that is older than timeout
now = NOW;
for (idx = 0 ; idx < HEADCOUNT; idx++) {
session = sessions.heads[idx];
while (session) {
next = session->next;
if (session->expiration < now)
afb_session_close(session);
session = next;
}
}
return now;
}
static void update_timeout(struct afb_session *session, time_t now, int timeout)
{
time_t expiration;
/* compute expiration */
if (timeout == AFB_SESSION_TIMEOUT_INFINITE)
expiration = MAX_EXPIRATION;
else {
if (timeout == AFB_SESSION_TIMEOUT_DEFAULT)
expiration = now + sessions.timeout;
else
expiration = now + timeout;
if (expiration < 0)
expiration = MAX_EXPIRATION;
}
/* record the values */
session->timeout = timeout;
session->expiration = expiration;
}
static void update_expiration(struct afb_session *session, time_t now)
{
update_timeout(session, now, session->timeout);
}
static struct afb_session *add_session (const char *uuid, int timeout, time_t now, int idx)
{
struct afb_session *session;
/* check arguments */
if (!AFB_SESSION_TIMEOUT_IS_VALID(timeout)
|| (uuid && strlen(uuid) >= sizeof session->uuid)) {
errno = EINVAL;
return NULL;
}
/* check session count */
if (sessions.count >= sessions.max) {
errno = EBUSY;
return NULL;
}
/* allocates a new one */
session = calloc(1, sizeof *session);
if (session == NULL) {
errno = ENOMEM;
return NULL;
}
/* initialize */
pthread_mutex_init(&session->mutex, NULL);
session->refcount = 1;
strcpy(session->uuid, uuid);
strcpy(session->token, sessions.initok);
update_timeout(session, now, timeout);
/* link */
session->idx = (char)idx;
session->next = sessions.heads[idx];
sessions.heads[idx] = session;
sessions.count++;
return session;
}
/* create a new session for the given timeout */
static struct afb_session *new_session (int timeout, time_t now)
{
int idx;
char uuid[SIZEUUID];
do {
new_uuid(uuid);
idx = pearson4(uuid);
} while(search(uuid, idx));
return add_session(uuid, timeout, now, idx);
}
/* Creates a new session with 'timeout' */
struct afb_session *afb_session_create (int timeout)
{
time_t now;
struct afb_session *session;
/* cleaning */
pthread_mutex_lock(&sessions.mutex);
now = cleanup();
session = new_session(timeout, now);
pthread_mutex_unlock(&sessions.mutex);
return session;
}
/* Searchs the session of 'uuid' */
struct afb_session *afb_session_search (const char *uuid)
{
struct afb_session *session;
/* cleaning */
pthread_mutex_lock(&sessions.mutex);
cleanup();
session = search(uuid, pearson4(uuid));
if (session)
__atomic_add_fetch(&session->refcount, 1, __ATOMIC_RELAXED);
pthread_mutex_unlock(&sessions.mutex);
return session;
}
/* This function will return exiting session or newly created session */
struct afb_session *afb_session_get (const char *uuid, int timeout, int *created)
{
int idx;
struct afb_session *session;
time_t now;
/* cleaning */
pthread_mutex_lock(&sessions.mutex);
now = cleanup();
/* search for an existing one not too old */
if (!uuid)
session = new_session(timeout, now);
else {
idx = pearson4(uuid);
session = search(uuid, idx);
if (session) {
__atomic_add_fetch(&session->refcount, 1, __ATOMIC_RELAXED);
pthread_mutex_unlock(&sessions.mutex);
if (created)
*created = 0;
return session;
}
session = add_session (uuid, timeout, now, idx);
}
pthread_mutex_unlock(&sessions.mutex);
if (created)
*created = !!session;
return session;
}
/* increase the use count on the session */
struct afb_session *afb_session_addref(struct afb_session *session)
{
if (session != NULL)
__atomic_add_fetch(&session->refcount, 1, __ATOMIC_RELAXED);
return session;
}
/* decrease the use count of the session */
void afb_session_unref(struct afb_session *session)
{
if (session != NULL) {
assert(session->refcount != 0);
if (!__atomic_sub_fetch(&session->refcount, 1, __ATOMIC_RELAXED)) {
pthread_mutex_lock(&session->mutex);
if (session->autoclose || session->uuid[0] == 0)
destroy (session);
else
pthread_mutex_unlock(&session->mutex);
}
}
}
// close Client Session Context
void afb_session_close (struct afb_session *session)
{
assert(session != NULL);
pthread_mutex_lock(&session->mutex);
if (session->uuid[0] != 0) {
session->uuid[0] = 0;
if (session->refcount)
close_session(session);
else {
destroy (session);
return;
}
}
pthread_mutex_unlock(&session->mutex);
}
/* set the autoclose flag */
void afb_session_set_autoclose(struct afb_session *session, int autoclose)
{
assert(session != NULL);
session->autoclose = (char)!!autoclose;
}
// is the session active?
int afb_session_is_active (struct afb_session *session)
{
assert(session != NULL);
return !!session->uuid[0];
}
// is the session closed?
int afb_session_is_closed (struct afb_session *session)
{
assert(session != NULL);
return !session->uuid[0];
}
// Sample Generic Ping Debug API
int afb_session_check_token (struct afb_session *session, const char *token)
{
assert(session != NULL);
assert(token != NULL);
if (!session->uuid[0])
return 0;
if (session->expiration < NOW)
return 0;
if (session->token[0] && strcmp (token, session->token) != 0)
return 0;
return 1;
}
// generate a new token and update client context
void afb_session_new_token (struct afb_session *session)
{
assert(session != NULL);
// Old token was valid let's regenerate a new one
new_uuid(session->token);
// keep track of time for session timeout and further clean up
update_expiration(session, NOW);
}
/* Returns the uuid of 'session' */
const char *afb_session_uuid (struct afb_session *session)
{
assert(session != NULL);
return session->uuid;
}
/* Returns the token of 'session' */
const char *afb_session_token (struct afb_session *session)
{
assert(session != NULL);
return session->token;
}
/**
* Get the index of the 'key' in the cookies array.
* @param key the key to scan
* @return the index of the list for key within cookies
*/
static int cookeyidx(const void *key)
{
intptr_t x = (intptr_t)key;
unsigned r = (unsigned)((x >> 5) ^ (x >> 15));
return r & COOKIEMASK;
}
/**
* Set, get, replace, remove a cookie of 'key' for the 'session'
*
* The behaviour of this function depends on its parameters:
*
* @param session the session
* @param key the key of the cookie
* @param makecb the creation function or NULL
* @param freecb the release function or NULL
* @param closure an argument for makecb or the value if makecb==NULL
* @param replace a boolean enforcing replecement of the previous value
*
* @return the value of the cookie
*
* The 'key' is a pointer and compared as pointers.
*
* For getting the current value of the cookie:
*
* afb_session_cookie(session, key, NULL, NULL, NULL, 0)
*
* For storing the value of the cookie
*
* afb_session_cookie(session, key, NULL, NULL, value, 1)
*/
void *afb_session_cookie(struct afb_session *session, const void *key, void *(*makecb)(void *closure), void (*freecb)(void *item), void *closure, int replace)
{
int idx;
void *value;
struct cookie *cookie, **prv;
/* get key hashed index */
idx = cookeyidx(key);
/* lock session and search for the cookie of 'key' */
lock(session);
prv = &session->cookies[idx];
for (;;) {
cookie = *prv;
if (!cookie) {
/* 'key' not found, create value using 'closure' and 'makecb' */
value = makecb ? makecb(closure) : closure;
/* store the the only if it has some meaning */
if (replace || makecb || freecb) {
cookie = malloc(sizeof *cookie);
if (!cookie) {
errno = ENOMEM;
/* calling freecb if there is no makecb may have issue */
if (makecb && freecb)
freecb(value);
value = NULL;
} else {
cookie->key = key;
cookie->value = value;
cookie->freecb = freecb;
cookie->next = NULL;
*prv = cookie;
}
}
break;
} else if (cookie->key == key) {
/* cookie of key found */
if (!replace)
/* not replacing, get the value */
value = cookie->value;
else {
/* create value using 'closure' and 'makecb' */
value = makecb ? makecb(closure) : closure;
/* free previous value is needed */
if (cookie->value != value && cookie->freecb)
cookie->freecb(cookie->value);
/* store the value and its releaser */
cookie->value = value;
cookie->freecb = freecb;
/* but if both are NULL drop the cookie */
if (!value && !freecb) {
*prv = cookie->next;
free(cookie);
}
}
break;
} else {
prv = &(cookie->next);
}
}
/* unlock the session and return the value */
unlock(session);
return value;
}
void *afb_session_get_cookie(struct afb_session *session, const void *key)
{
return afb_session_cookie(session, key, NULL, NULL, NULL, 0);
}
int afb_session_set_cookie(struct afb_session *session, const void *key, void *value, void (*freecb)(void*))
{
return -(value != afb_session_cookie(session, key, NULL, freecb, value, 1));
}
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