A toy HTTP server in pure Python3 I wrote in September 2013

dummyhttp.py

#! /usr/bin/env python

import sys
import os
import locale
from collections import defaultdict
from socket import socket, AF_INET, SOCK_STREAM
from urllib.parse import urlparse
from contextlib import closing
from functools import wraps

import magic

args = dict(enumerate(sys.argv))

encoding_guesser = magic.Magic(mime_encoding=True)

curdir = os.path.abspath(b'.')

ENCODING = locale.getlocale()[1]

HTTP_METHODS = frozenset({b'OPTIONS', b'GET', b'HEAD', b'POST', b'PUT', b'DELETE', b'TRACE', b'CONNECT'})

HTTP_VERSION = b'HTTP/1.1'

def parse_path(f):
    @wraps(f)
    def handler(resource, headers):
        if not resource.startswith(b'/'):
            resource = urlparse(resource).path or b'/'
        resource = os.path.abspath(resource[1:] or b'.')
        if not resource.startswith(curdir):
            resource = curdir
        return f(resource, headers)
    return handler

def guess_type(path):
    typ = magic.from_file(path, mime=True)
    if typ.startswith(b'text'):
        return typ + b"; charset=" + encoding_guesser.from_file(path)
    else:
        return typ

def file_browser(path):
    headers = {b'Connection': b'close'}
    if not os.path.exists(path):
        return (None, headers)
    elif os.path.isdir(path):
        content_reader = lambda: b"\n".join(p for p in os.listdir(path) if not p.startswith(b'.'))
        headers.update({b'Content-Type': b'text/plain; charset=UTF-8'})
        return (content_reader, headers)
    else:
        headers.update({b'Content-Type': guess_type(path.decode())})
        def content_reader():
            with open(path, 'rb') as f:
                return f.read()
        return (content_reader, headers)


def build_response(resource, headers, handler):
    content, response_headers = file_browser(resource)
    if content is None:
        return HTTP_VERSION + b" 404 File Not Found\r\n\r\n"
    else:
        status_line = b" ".join([HTTP_VERSION, b'202', b'Accepted'])
        headers_bytes = b"\r\n".join(map(b':'.join, response_headers.items())) + b'\r\n'
        return handler(status_line, headers_bytes, content)

@parse_path
def handle_GET(resource, headers):
    def handler(status_line, headers_bytes, content_reader):
        return b"\r\n".join([status_line, headers_bytes, content_reader()])
    return build_response(resource, headers, handler)

@parse_path
def handle_HEAD(resource, headers):
    def handler(status_line, headers_bytes, content):
        return b"\r\n".join([status_line, headers_bytes, b''])
    return build_response(resource, headers, handler)


def missing_method(resource, headers):
    return HTTP_VERSION + b" 405 Method Not Allowed\r\n\r\n"


methodmap = defaultdict(lambda : missing_method)
methodmap.update({b'GET': handle_GET, b'HEAD': handle_HEAD})

def handle_client(sock):
    data = sock.recv(1000)
    while not data.endswith(b"\r\n\r\n"):
        newdata = sock.recv(1000)
        if not newdata:
            return
        data += newdata
    headers = data.strip().splitlines()
    request, headers = headers[0], headers[1:]
    headers = dict(map(lambda s: s.split(b':', 1), headers))
    try:
        method, resource, http_version = request.split()
    except ValueError:
        response = HTTP_VERSION + b" 400 Bad Request\r\n\r\n"
    else:
        if method not in HTTP_METHODS:
            response = HTTP_VERSION + b" 501 Not Implemented\r\n\r\n"
        else:
            response = methodmap[method](resource, headers)
    sock.sendall(response)

if __name__ == '__main__':
    sock = socket(AF_INET, SOCK_STREAM)
    sock.bind(('', int(args.get(1, 8080))))
    sock.listen(1000)
    while True:
        with closing(sock.accept()[0]) as newsock:
            handle_client(newsock)