esp-sample-function.js

var crypto = require('crypto');
module.exports = function(original_url, branch_base_url, branch_hmac_secret, three_p_url) {
	if (!original_url) { return new Error('Missing original_url'); }
	if (typeof original_url != 'string') { return new Error('Invalid original_url'); }
	if (!branch_base_url) { return new Error('Missing branch_base_url, should be similar to https://bnc.lt/abcd/3p?%243p=xx'); }
	if (typeof branch_base_url != 'string') { return new Error('Invalid branch_base_url'); }
	if (!branch_hmac_secret) { return new Error('Missing branch_hmac_secret'); }
	if (typeof branch_hmac_secret != 'string') { return new Error('Invalid branch_hmac_secret'); }
	if (three_p_url && typeof three_p_url != 'string') { return new Error('Invalid three_p_url'); }

	var pre_hmac_url = branch_base_url + (three_p_url ? '&%243p_url=' + encodeURIComponent(three_p_url) : '') + '&%24original_url=' + encodeURIComponent(original_url),
		hmac = crypto.createHmac('sha256', branch_hmac_secret).update(pre_hmac_url).digest('hex');
	return pre_hmac_url + '&%24hmac=' + hmac;
};

// Tests
// console.log('Test with 3P URL:', module.exports('http://originalurl.com/?utm=y', 'http://dev.bnc.lt/tjgc/3p?%243p=np', 'SECRET HERE', 'http://example.com/this-is-an-3p-url?foo=bar'));
// console.log('Test without 3P URL:', module.exports('http://originalurl.com/?utm=y', 'http://dev.bnc.lt/tjgc/3p?%243p=np', 'SECRET HERE', null));

esp-sample-function.py

import hmac
import hashlib


import urllib

safe_chars = '~()*!.\''

def getBranchLink(original_url, branch_base_url, branch_hmac_secret, three_p_url):
	if original_url is None:
		raise Exception('Missing original_url')
	if type(original_url) is not str:
		raise Exception('Invalid original_url')
	if branch_base_url is None:
		raise Exception('Missing branch_base_url, should be similar to https://bnc.lt/abcd/3p?3p=xx')
	if type(branch_base_url) is not str:
		raise Exception('Invalid branch_base_url')
	if branch_hmac_secret is None:
		raise Exception('Missing branch_hmac_secret')
	if type(branch_hmac_secret) is not str:
		raise Exception('Invalid branch_hmac_secret')
	if three_p_url and type(three_p_url) is not str:
		raise Exception('Invalid three_p_url')

	pre_hmac_url = branch_base_url;
	if three_p_url is not None:
		pre_hmac_url += '&%243p_url=' + urllib.quote(three_p_url.encode("utf-8"), safe=safe_chars)
	pre_hmac_url += '&%24original_url=' + urllib.quote(original_url.encode("utf-8"), safe=safe_chars)
	hmac_for_url = hmac.new(branch_hmac_secret, pre_hmac_url, hashlib.sha256).hexdigest()
	return pre_hmac_url + '&%24hmac=' + hmac_for_url

def main():
	## Tests
	## print 'Test with 3P URL: ' + getBranchLink('http://originalurl.com/?utm=y', 'http://dev.bnc.lt/tjgc/3p?%243p=np', 'SECRET HERE', 'http://example.com/this-is-an-3p-url?foo=bar');
	## print 'Test without 3P URL: ' + getBranchLink('http://originalurl.com/?utm=y', 'http://dev.bnc.lt/tjgc/3p?%243p=np', 'SECRET HERE', None);

if __name__ == '__main__':
    main()