Customizing Python's SimpleHTTPServer
source link: https://parsiya.net/blog/2020-11-15-customizing-pythons-simplehttpserver/
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Nov 15, 2020 - 3 minute read - Comments - python
Customizing Python's SimpleHTTPServer
The other day I customized the Python built-in SimpleHTTPServer with some routes. I did not find a lot of info about it (most use it to serve files). This is how I did some basic customization.
This is for Python 3.8.6 (which what I have in my testing VM) but it should work on Python 3.9 (and probably the same for Python 2).
Code is at https://github.com/parsiya/Parsia-Code/tree/master/python-simplehttpserver.
How to Serve Files
python -m http.server 8080 --bind 127.0.0.1
.
Custom GET Responses
But I needed to customize the path. Let's start with a simple implementation. We need to create our own BaseHTTPRequestHandler.
from http.server import HTTPServer, BaseHTTPRequestHandler
class MyHandler(BaseHTTPRequestHandler):
def do_GET(self):
pass
httpd = HTTPServer(('localhost', 10000), MyHandler)
httpd.serve_forever()
To respond to GET requests we need to add code to do_GET
. Let's say we want to
return a 200 response that says It works!
.
# 01.py
def do_GET(self):
# send 200 response
self.send_response(200)
# send response headers
self.end_headers()
# send the body of the response
self.wfile.write(bytes("01.py", "utf-8"))
Custom Response Headers
Note the server adds some default headers. To modify these we can use
send_header before calling end_headers. This is
very useful for adding the Content-Type
header.
# 02.py
def do_GET(self):
# send 200 response
self.send_response(200)
# add our own custom header
self.send_header("myheader", "myvalue")
# send response headers
self.end_headers()
# send the body of the response
self.wfile.write(bytes("It Works!", "utf-8"))
To override a header we cannot use send_header
because it will just add it as
a new header to the response. Based on the documentation it seems like the
Date
and Server
response headers cannot be changed :(.
Read Request Headers
I needed to read the incoming request headers. These are stored in the
headers object. It is of type http.client.HTTPMessage
which is a
subclass of email.message.Message.
We can get the value of any header by name with headers.get("header name")
. To
get all values for a specific header (because headers can be repeated) use
headers.get_all("header name")
.
# 03.py
def do_GET(self):
# get the value of the "Authorization" header and echo it.
authz = self.headers.get("authorization")
# send 200 response
self.send_response(200)
# send response headers
self.end_headers()
# send the body of the response
self.wfile.write(bytes(authz, "utf-8"))
Note: Header names are not case-sensitive in HTTP (or here).
03.pyReading The Body of POST Requests
To handle POST requests we need to implement do_POST
(d'oh). To read the body
of the POST request we:
- Read the
Content-Length
header in the incoming request. Read that many bytes from
self.rfile
.I could not find a way to read "all bytes" in
rfile
. I had to rely on the header.def do_POST(self): # read the content-length header content_length = int(self.headers.get("Content-Length")) # read that many bytes from the body of the request body = self.rfile.read(content_length) self.send_response(200) self.end_headers() # echo the body in the response self.wfile.write(body)
Server Over TLS
First, you need to create a private key and certificate in pem
format. To
create a self-signed certificate/key in one go:
openssl req -newkey rsa:2048 -nodes -keyout key.pem -x509 -days 365 -out certificate.pem
Then modify the last lines of the script to:
httpd = HTTPServer(('localhost', 443), MyHandler)
httpd.socket = ssl.wrap_socket(httpd.socket, server_side=True, certfile="certificate.pem", keyfile="key.pem")
httpd.serve_forever()
Posted by Parsia Nov 15, 2020
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