Pati Ram Yadav Pati Ram Yadav - 3 years ago 112
Python Question

XMLHttpRequest cannot load http://host1:5000/path using angular $resource front end or python/cgi script in backend

XMLHttpRequest cannot load http://host1:5000/endpoint. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://originhost:3000' is therefore not allowed access.

How can solve this problem using anguarjs from front side or server side (Python CGI script). I don't have right to change anything with browser, crome or security and even not possible with request.

Angular Code front end:



function scheduleReportServiceFactory($resource){
var schedule_report_url = 'http://host1/endpoint:bucket';
var auth = btoa("xyz:xyz");
var headers = {
"Authorization" : "Basic " + auth,
'Content-Type': 'application/json',
'Access-Control-Allow-Origin': 'http://originhost:3000'
};
return {
schedule_report : $resource(schedule_report_url, {}, {
query : {
method : 'GET',
params : {
bucket : '@bucket'
},
headers: headers,
cache : true,
}
})
};

}




Python code backend:


import .....


class Dispatcher(object):

def not_found(self, environ, start_response):
start_response('404 Not Found', [('Content-Type', 'application/octet-stream')])
return []

def __init__(self, mounts=None):
self.mounts = mounts or {}

def __call__(self, environ, start_response):
script = environ.get('PATH_INFO', '')
while '/' in script:
if script in self.mounts:
app = self.mounts[script]
break
script, last_item = script.rsplit('/', 1)
else:
app = self.mounts.get(script, self.not_found)
return app(environ, start_response)

print >> sys.stderr, "app.cgi: server starting", os.environ.get('PATH_INFO')
for k in os.environ:
print >>sys.stderr, k, os.environ[k]

app = Dispatcher({
'/xyz/report/v1': report_app(),
'/xyz/replication/v1': dr_app(),
})
if __name__ == '__main__':
os.environ['DEBUG'] = '1'
from werkzeug.serving import run_simple
run_simple('0.0.0.0', 5000, app, use_debugger=True, use_reloader=True)
else:
CGIHandler().run(app)





For more information:



-sh-4.2$ curl -u xyz -H "Origin originhost:3000" --verbose localhost:5000/endpoint/xyz
Enter host password for user 'xyz':
* About to connect() to localhost port 5000 (#0)
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 5000 (#0)
* Server auth using Basic with user 'xyz'
> GET /endpoint/xyz HTTP/1.1
> Authorization: Basic emt5ajM0aTowNjZCZXg0MjU=
> User-Agent: curl/7.29.0
> Host: localhost:5000
> Accept: */*
> Origin originhost:3000
>
* HTTP 1.0, assume close after body
< HTTP/1.0 401 UNAUTHORIZED
< Content-Type: application/octet-stream
* Authentication problem. Ignoring this.
< WWW-Authenticate: Basic
< Content-Length: 0
< Server: Werkzeug/0.12.2 Python/2.7.5
< Date: Mon, 24 Jul 2017 18:22:26 GMT
<
* Closing connection 0


-sh-4.2$ curl -u xyz -H "Origin originhost:3000" -H "Access-Control-Request-Method: GET" -H "Access-Control-Request-Headers: X-Requested-With" -X OPTIONS --verbose localhost:5000/endpiont/xyz
Enter host password for user 'xyz':
* About to connect() to localhost port 5000 (#0)
* Trying 127.0.0.1...
* Connected to localhost (127.0.0.1) port 5000 (#0)
* Server auth using Basic with user 'xyz'
> OPTIONS endpoint/xyz HTTP/1.1
> Authorization: Basic emt5ajM0afhtTowNjZCZXg0Mg==
> User-Agent: curl/7.29.0
> Host: localhost:5000
> Accept: */*
> Origin originhost:3000
> Access-Control-Request-Method: GET
> Access-Control-Request-Headers: X-Requested-With
>
* HTTP 1.0, assume close after body
< HTTP/1.0 200 OK
< Content-Type: text/html; charset=utf-8
< Allow: HEAD, GET, POST, OPTIONS, DELETE
< Content-Length: 0
< Server: Werkzeug/0.12.2 Python/2.7.5
< Date: Mon, 24 Jul 2017 18:24:53 GMT
<
* Closing connection 0




Answer Source

I think your problem is not on the Front end but on the SERVER SIDE .. it's a CORS problem .. you need to allow on the server the back end to get request from your front end ...

I don't know how to do it in Python but basically it's possible in all languages

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