在Node.js（Express）中获取signed_request Facebook的画布应用程序

Question

有没有什么办法如何获取和解析Node.js Facebook页面选项卡应用程序中的signed_request？我需要知道页面ID，如果用户喜欢这个页面...

Answer 1

我之前做过这个，最后写了一个小型库来完成它。原来的CoffeeScript可以在https://gist.github.com/fbef51815ab6f062b51a#file_signed_request.coffee发现，这里是一个JavaScript翻译：

var crypto = require('crypto'); 

SignedRequest = (function() { 

    function SignedRequest(secret, request) { 
    this.secret = secret; 
    this.request = request; 
    this.verify = this.verify.bind(this); 

    var parts = this.request.split('.'); 
    this.encodedSignature = parts[0]; 
    this.encoded = parts[1]; 
    this.signature = this.base64decode(this.encodedSignature); 
    this.decoded = this.base64decode(this.encoded); 
    this.data = JSON.parse(this.decoded); 
    } 

    SignedRequest.prototype.verify = function() { 
    if (this.data.algorithm !== 'HMAC-SHA256') { 
     return false; 
    } 
    var hmac = crypto.createHmac('SHA256', this.secret); 
    hmac.update(this.encoded); 
    var result = hmac.digest('base64').replace(/\//g, '_').replace(/\+/g, '-').replace(/\=/g, ''); 
    return result === this.encodedSignature; 
    }; 

    SignedRequest.prototype.base64encode = function(data) { 
    return new Buffer(data, 'utf8').toString('base64').replace(/\//g, '_').replace(/\+/g, '-').replace(/\=/g, ''); 
    }; 

    SignedRequest.prototype.base64decode = function(data) { 
    while (data.length % 4 !== 0) { 
     data += '='; 
    } 
    data = data.replace(/-/g, '+').replace(/_/g, '/'); 
    return new Buffer(data, 'base64').toString('utf-8'); 
    }; 

    return SignedRequest; 

})(); 

module.exports = SignedRequest; 

您可以使用这样的：

var verifier = new SignedRequest(clientSecret, signedRequest); 
verifier.verify() // whether or not the signed request verifies 
verifier.data // the data from the signed request