Python – Sending custom headers in websocket handshake

Updated 2x

Short answer: No, only the path and protocol field can be specified.

Longer answer:

There is no method in the JavaScript WebSockets API for specifying additional headers for the client/browser to send. The HTTP path ("GET /xyz") and protocol header ("Sec-WebSocket-Protocol") can be specified in the WebSocket constructor.

The Sec-WebSocket-Protocol header (which is sometimes extended to be used in websocket specific authentication) is generated from the optional second argument to the WebSocket constructor:

var ws = new WebSocket("ws://example.com/path", "protocol");
var ws = new WebSocket("ws://example.com/path", ["protocol1", "protocol2"]);

The above results in the following headers:

Sec-WebSocket-Protocol: protocol

and

Sec-WebSocket-Protocol: protocol1, protocol2

A common pattern for achieving WebSocket authentication/authorization is to implement a ticketing system where the page hosting the WebSocket client requests a ticket from the server and then passes this ticket during WebSocket connection setup either in the URL/query string, in the protocol field, or required as the first message after the connection is established. The server then only allows the connection to continue if the ticket is valid (exists, has not been already used, client IP encoded in ticket matches, timestamp in ticket is recent, etc). Here is a summary of WebSocket security information: https://devcenter.heroku.com/articles/websocket-security

Basic authentication was formerly an option but this has been deprecated and modern browsers don't send the header even if it is specified.

Basic Auth Info (Deprecated - No longer functional):

NOTE: the following information is no longer accurate in any modern browsers.

The Authorization header is generated from the username and password (or just username) field of the WebSocket URI:

var ws = new WebSocket("ws://username:password@example.com")

The above results in the following header with the string "username:password" base64 encoded:

Authorization: Basic dXNlcm5hbWU6cGFzc3dvcmQ=

I have tested basic auth in Chrome 55 and Firefox 50 and verified that the basic auth info is indeed negotiated with the server (this may not work in Safari).

Thanks to Dmitry Frank's for the basic auth answer

The user-agent should be specified as a field in the header.

Here is a list of HTTP header fields, and you'd probably be interested in request-specific fields, which includes User-Agent.

If you're using requests v2.13 and newer

The simplest way to do what you want is to create a dictionary and specify your headers directly, like so:

import requests

url = 'SOME URL'

headers = {
    'User-Agent': 'My User Agent 1.0',
    'From': 'youremail@domain.com'  # This is another valid field
}

response = requests.get(url, headers=headers)

If you're using requests v2.12.x and older

Older versions of requests clobbered default headers, so you'd want to do the following to preserve default headers and then add your own to them.

import requests

url = 'SOME URL'

# Get a copy of the default headers that requests would use
headers = requests.utils.default_headers()

# Update the headers with your custom ones
# You don't have to worry about case-sensitivity with
# the dictionary keys, because default_headers uses a custom
# CaseInsensitiveDict implementation within requests' source code.
headers.update(
    {
        'User-Agent': 'My User Agent 1.0',
    }
)

response = requests.get(url, headers=headers)