Files
successfactors-python/Lambda/lambda_function.py
2023-05-02 08:40:12 -04:00

140 lines
3.9 KiB
Python

#!/usr/bin/env python3
import base64
import json
import sys
import os
import requests
import xmlsec
import boto3
from lxml import etree
from datetime import datetime, timedelta
region = os.environ.get('AWS_REGION')
secret_id= os.environ.get('SECRET_ID')
template_file = 'sf_saml_template.xml'
private_keyfile = '/tmp/successfactors-private.pem'
def get_secret(region, secret_name, session):
client = session.client(
service_name='secretsmanager',
region_name=region
)
try:
get_secret_value_response = client.get_secret_value(
SecretId=secret_name
)
if 'SecretString' in get_secret_value_response:
secret = get_secret_value_response['SecretString']
except Exception as x:
print(x)
sys.exit(1)
return secret
def get_access_token(sf_url, company_id, client_id, assertion):
token_request = dict(
client_id=client_id,
company_id=company_id,
grant_type='urn:ietf:params:oauth:grant-type:saml2-bearer',
assertion=assertion
)
response = requests.post(f"{sf_url}/oauth/token", data=token_request)
token_data = response.json()
return token_data['access_token']
def generate_assertion(sf_root_url, user_id, client_id, template_file):
issue_instant = datetime.utcnow()
auth_instant = issue_instant
not_valid_before = issue_instant - timedelta(minutes=10)
not_valid_after = issue_instant + timedelta(minutes=10)
audience = 'www.successfactors.com'
context = dict(
issue_instant=issue_instant.isoformat(),
auth_instant=auth_instant.isoformat(),
not_valid_before=not_valid_before.isoformat(),
not_valid_after=not_valid_after.isoformat(),
sf_root_url=sf_root_url,
audience=audience,
user_id=user_id,
client_id=client_id,
session_id='mock_session_index',
)
saml_template = open(template_file).read()
return saml_template.format(**context)
def sign_assertion(xml_string, private_key):
key = xmlsec.Key.from_file(private_key, xmlsec.KeyFormat.PEM)
root = etree.fromstring(xml_string)
signature_node = xmlsec.tree.find_node(root, xmlsec.Node.SIGNATURE)
sign_context = xmlsec.SignatureContext()
sign_context.key = key
sign_context.sign(signature_node)
return etree.tostring(root)
def auth(sf_url, sf_company_id, sf_oauth_client_id,
sf_admin_user, sf_saml_private_key, template_file):
unsigned_assertion = generate_assertion(sf_url,
sf_admin_user,
sf_oauth_client_id,
template_file)
signed_assertion = sign_assertion(unsigned_assertion, sf_saml_private_key)
signed_assertion_b64 = base64.b64encode(signed_assertion).replace(b'\n', b'')
access_token = get_access_token(sf_url,
sf_company_id,
sf_oauth_client_id,
signed_assertion_b64)
return access_token
def lambda_handler(event, context):
session = boto3.session.Session()
print(event)
if event['rawPath'] == '/token':
body = json.loads(event['body'])
sf_url = body['odata_url']
sf_company_id = body['company_id']
sf_oauth_client_id = body['oauth_client_id']
sf_admin_user = body['admin_user']
private_key = get_secret(region,
secret_id,
session)
with open(private_keyfile, 'w') as f:
f.write(private_key)
token = auth(sf_url, sf_company_id, sf_oauth_client_id, sf_admin_user,
private_keyfile, template_file)
payload = {
"token": token
}
return {
'statusCode': 200,
'body': json.dumps(payload)
}