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Assignment 3 #125

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4388089
It works.
marcteale Jan 19, 2016
f40f4e3
Assignment 3
marcteale Jan 26, 2016
62f6b2c
Remove 'How I Explained REST to My Wife'
Jul 12, 2016
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92 changes: 82 additions & 10 deletions resources/session02/http_server.py
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Original file line number Diff line number Diff line change
@@ -1,12 +1,73 @@
import socket
import sys
import mimetypes
import os.path


def response_ok(body=b"this is a pretty minimal response", mimetype=b"text/plain"):
"""returns a basic HTTP response"""
mimetype = b"content-type:" + mimetype
resp = []
resp.append(b"HTTP/1.1 200 OK")
resp.append(mimetype)
resp.append(b"")
resp.append(body)
return b"\r\n".join(resp)


def response_method_not_allowed():
"""returns a 405 Method Not Allowed response"""
resp = []
resp.append("HTTP/1.1 405 Method Not Allowed")
resp.append("")
return "\r\n".join(resp).encode('utf8')


def response_not_found():
"""returns a 404 Not Found response"""
return b"HTTP/1.1 404 Not Found"


def parse_request(request):
first_line = request.split("\r\n", 1)[0]
try:
method, uri, protocol = first_line.split()
# Chrome seems to be sending a zero-length request that breaks the split.
except ValueError:
print('The client tried to break me. Request was: \'{}\''.format(request))
method = ''
if method != "GET":
raise NotImplementedError("We only accept GET")
return uri


def resolve_uri(uri):
"""Return appropriate content and a mime type"""
# Return the contents of a file if it exists
uri = os.getcwd() + uri
if os.path.isfile(uri):
mime_type, _ = mimetypes.guess_type(uri)
mime_type = mime_type.encode('utf8')
with open(uri, "rb") as content_file:
f = content_file.read()
content = bytearray(f)
# Return an index if a directory is requested
elif os.path.isdir(uri):
mime_type = b'text/plain'
filelist = os.listdir(uri)
filelist.sort
content = '\r\n'.join(filelist)
content = content.encode('utf8')
else:
raise NameError
return content, mime_type


def server(log_buffer=sys.stderr):
address = ('127.0.0.1', 10000)
address = ('0.0.0.0', 10000) # I'm running this from a remote VM
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
print("making a server on {0}:{1}".format(*address), file=log_buffer)
print("making a server on {0}:{1}".format(*address), file=log_buffer) # NOQA
sock.bind(address)
sock.listen(1)

Expand All @@ -16,16 +77,27 @@ def server(log_buffer=sys.stderr):
conn, addr = sock.accept() # blocking
try:
print('connection - {0}:{1}'.format(*addr), file=log_buffer)
request = ''
while True:
data = conn.recv(16)
print('received "{0}"'.format(data), file=log_buffer)
if data:
print('sending data back to client', file=log_buffer)
conn.sendall(data)
else:
msg = 'no more data from {0}:{1}'.format(*addr)
print(msg, log_buffer)
data = conn.recv(1024)
request += data.decode('utf8')
if len(data) < 1024:
break

try:
uri = parse_request(request)
except NotImplementedError:
response = response_method_not_allowed()
else:
try:
content, mime_type = resolve_uri(uri)
except NameError:
response = response_not_found()
else:
response = response_ok(content, mime_type)

print('sending response', file=log_buffer)
conn.sendall(response)
finally:
conn.close()

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136 changes: 136 additions & 0 deletions resources/session03/wsgi/calculator.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,136 @@
#!/usr/bin/python
# import cgitb
from urllib.parse import urlparse

# cgitb.enable()


def parse_path(referer):
'''
Parse the path provided and respond with appropriate content. Returns the
status of the request and content of response.
'''
response = ''
status = '200 OK'

scheme, netloc, path, params, query, fragment = urlparse(referer)
baseurl = "{}://{}/".format(scheme, netloc)

args = path.split('/')
args.pop(0) # First element is always a null string, get rid of it

# We only support paths, return a 501 if we get anything else
if params or query or fragment != '':
raise NotImplementedError
# Send the examples
if path == '/' or '':
response = """
<h1>Instructions for use:</h1>
<h2>Separate all arguments with slashes.</h2>
<h3>Multiply</h3>
<p>Append 'multiply' to the URL string followed by the multiplicands.</p>
<a href="{0}multiply/3/4">{0}multiply/3/4</a> = 12
<h3>Divide</h3>
<p>Append 'divide', then the dividend and divisor.</p>
Example: <a href="{0}divide/12/4">{0}divide/12/4</a> = 3
<h3>Add</h3>
<p>Append 'add', followed by any number of addends.</p>
Example: <a href="{0}add/23/52">{0}add/23/52</a> = 75
<h3>Subtract</h3>
<p>Append 'subtract', followed by the minuend and the subtrahend. (I had no idea those were words before today.)</p>
Example: <a href="{0}subtract/36/4">{0}subtract/36/4</a> = 12
""".format(baseurl)
# Do the math
elif args[0].lower() == 'multiply' or 'divide' or 'add' or 'subtract':
response = do_some_math(args)
# This is supposed to return a NameError when the path doesn't match, but it
# returns a 500 instead. I can't figure out why.
else:
raise NameError
return status, response


def do_some_math(args):
operation = args[0]
args.pop(0)
if len(args) > 2:
raise SyntaxError
first = float(args[0])
second = float(args[1])
if operation == 'subtract':
operator = '-'
result = first - second
elif operation == 'divide':
if float(second) == 0.0:
raise ValueError
operator = '/'
result = first / second
elif operation == 'multiply':
operator = '*'
result = first * second
else:
operator = '+'
result = first + second
content = "{} {} {} = {}".format(first, operator, second, result)

return content


def error_content(status_code, referer):
'''
Creates error pages based on an intentionally limited number of HTTP error
codes. Returns the HTTP error code string and content of the error message.
'''
error_codes = {400: '400 Bad request',
404: '404 Not Found',
500: '500 Internal Server Error',
501: '501 Not Implemented'
}
scheme, netloc, path, params, query, fragment = urlparse(referer)
status_str = error_codes[status_code]
content = '<h1>{}</h1>Referer was <a href="{}">{}</a>'.format(status_str, referer, referer)
return status_str, content


def application(environ, start_response):
header = """<html>
<head>
<title>WSGI Calculator</title>
</head>
<body>"""
footer = """
</body>
</html>"""

# I'm sure there was an easier way to get the full request, but I couldn't find it.
http_host = environ.get('HTTP_HOST', None)
path = environ.get('PATH_INFO', None)
query_string = environ.get('QUERY_STRING', None)
examples = '<p><a href="http://{}/">Examples</a>'.format(http_host)
if query_string == '':
request = "http://{}{}".format(http_host, path)
else:
request = "http://{}{}?{}".format(http_host, path, query_string)

try:
status, content = parse_path(request)
except SyntaxError or ValueError:
status, content = error_content(400, request)
except NameError:
status, content = error_content(404, request)
except NotImplementedError:
status, content = error_content(501, request)
except Exception:
status, content = error_content(500, request)

content = header + content + examples + footer
response_headers = [('Content-Type', 'text/html'),
('Content-Length', str(len(content)))]
start_response(status, response_headers)
return[content.encode('utf8')]


if __name__ == '__main__':
from wsgiref.simple_server import make_server
srv = make_server('0.0.0.0', 8080, application)
srv.serve_forever()
2 changes: 0 additions & 2 deletions source/readings.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -145,8 +145,6 @@ Session 4 - APIs and Mashups
* `xmlrpc spec (short) <http://www.xmlrpc.com/spec>`_
* `the SOAP specification <http://www.w3.org/TR/soap/>`_
* `json overview and spec (short) <http://www.json.org/>`_
* `How I Explained REST to My Wife (Tomayko 2004)
<http://tomayko.com/writings/rest-to-my-wife>`_
* `A Brief Introduction to REST (Tilkov 2007)
<http://www.infoq.com/articles/rest-introduction>`_
* `Wikipedia on REST
Expand Down