forked from koajs/session
/
context.js
279 lines (236 loc) · 6.49 KB
/
context.js
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'use strict';
const debug = require('debug')('koa-session:context');
const Session = require('./session');
const util = require('./util');
const ONE_DAY = 24 * 60 * 60 * 1000;
class ContextSession {
/**
* context session constructor
* @api public
*/
constructor(ctx, opts) {
this.ctx = ctx;
this.opts = opts || {};
this.store = this.opts.ContextStore ? new this.opts.ContextStore(ctx) : this.opts.store;
}
/**
* internal logic of `ctx.session`
* @return {Session} session object
*
* @api public
*/
get() {
const session = this.session;
// already retrieved
if (session) return session;
// unset
if (session === false) return null;
// cookie session store
if (!this.store) this.initFromCookie();
return this.session;
}
/**
* internal logic of `ctx.session=`
* @param {Object} val session object
*
* @api public
*/
set(val) {
if (val === null) {
this.session = false;
return;
}
if (typeof val === 'object') {
// use the original `externalKey` if exists to avoid waste storage
this.create(val, this.externalKey);
return;
}
throw new Error('this.session can only be set as null or an object.');
}
/**
* init session from external store
* will be called in the front of session middleware
*
* @api public
*/
async initFromExternal() {
debug('init from external');
const ctx = this.ctx;
const opts = this.opts;
const externalKey = ctx.cookies.get(opts.key, opts);
debug('get external key from cookie %s', externalKey);
if (!externalKey) {
// create a new `externalKey`
this.create();
return;
}
const json = await this.store.get(externalKey, opts.maxAge, { rolling: opts.rolling });
if (!this.valid(json)) {
// create a new `externalKey`
this.create();
return;
}
// create with original `externalKey`
this.create(json, externalKey);
this.prevHash = util.hash(this.session.toJSON());
}
/**
* init session from cookie
* @api private
*/
initFromCookie() {
debug('init from cookie');
const ctx = this.ctx;
const opts = this.opts;
const cookie = ctx.cookies.get(opts.key, opts);
if (!cookie) {
this.create();
return;
}
let json;
debug('parse %s', cookie);
try {
json = opts.decode(cookie);
} catch (err) {
// backwards compatibility:
// create a new session if parsing fails.
// Buffer.alloc(size, string, 'base64') does not seem to crash
// when `string` is not base64-encoded.
// but `JSON.parse(string)` will crash.
debug('decode %j error: %s', cookie, err);
if (!(err instanceof SyntaxError)) {
// clean this cookie to ensure next request won't throw again
ctx.cookies.set(opts.key, '', opts);
// ctx.onerror will unset all headers, and set those specified in err
err.headers = {
'set-cookie': ctx.response.get('set-cookie'),
};
throw err;
}
this.create();
return;
}
debug('parsed %j', json);
if (!this.valid(json)) {
this.create();
return;
}
// support access `ctx.session` before session middleware
this.create(json);
this.prevHash = util.hash(this.session.toJSON());
}
/**
* verify session(expired or )
* @param {Object} json session object
* @return {Boolean} valid
* @api private
*/
valid(json) {
if (!json) return false;
if (json._expire && json._expire < Date.now()) {
debug('expired session');
return false;
}
const valid = this.opts.valid;
if (typeof valid === 'function' && !valid(this.ctx, json)) {
// valid session value fail, ignore this session
debug('invalid session');
return false;
}
return true;
}
/**
* create a new session and attach to ctx.sess
*
* @param {Object} [val] session data
* @param {String} [externalKey] session external key
* @api private
*/
create(val, externalKey) {
debug('create session with val: %j externalKey: %s', val, externalKey);
if (this.store) this.externalKey = externalKey || this.opts.genid();
this.session = new Session(this.ctx, val);
}
/**
* Commit the session changes or removal.
*
* @api public
*/
async commit() {
const session = this.session;
const prevHash = this.prevHash;
const opts = this.opts;
const ctx = this.ctx;
// not accessed
if (undefined === session) return;
// removed
if (session === false) {
await this.remove();
return;
}
// force save session when `session._requireSave` set
let changed = true;
if (!session._requireSave) {
const json = session.toJSON();
// do nothing if new and not populated
if (!prevHash && !Object.keys(json).length) return;
changed = prevHash !== util.hash(json);
// do nothing if not changed and not in rolling mode
if (!this.opts.rolling && !changed) return;
}
if (typeof opts.beforeSave === 'function') {
debug('before save');
opts.beforeSave(ctx, session);
}
await this.save(changed);
}
/**
* remove session
* @api private
*/
async remove() {
const opts = this.opts;
const ctx = this.ctx;
const key = opts.key;
const externalKey = this.externalKey;
if (externalKey) await this.store.destroy(externalKey);
ctx.cookies.set(key, '', opts);
}
/**
* save session
* @api private
*/
async save(changed) {
const opts = this.opts;
const key = opts.key;
const externalKey = this.externalKey;
let json = this.session.toJSON();
// set expire for check
const maxAge = opts.maxAge ? opts.maxAge : ONE_DAY;
if (maxAge === 'session') {
// do not set _expire in json if maxAge is set to 'session'
// also delete maxAge from options
opts.maxAge = undefined;
} else {
// set expire for check
json._expire = maxAge + Date.now();
json._maxAge = maxAge;
}
// save to external store
if (externalKey) {
debug('save %j to external key %s', json, externalKey);
await this.store.set(externalKey, json, maxAge, {
changed,
rolling: opts.rolling,
});
this.ctx.cookies.set(key, externalKey, opts);
return;
}
// save to cookie
debug('save %j to cookie', json);
json = opts.encode(json);
debug('save %s', json);
this.ctx.cookies.set(key, json, opts);
}
}
module.exports = ContextSession;