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dumdum.py
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dumdum.py
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# -*- coding: utf-8 -*-
"""
A grammar to define "dummy" endpoints and behaviors based on parameters.
"""
import os, sys, json, re, time, logging
from urlparse import urlparse
from pyparsing import *
from cgi import parse_qs
import pprint
logger = logging.getLogger(__name__)
# Debug stuff
PP = pprint.PrettyPrinter(indent=2)
def dbg(o):
if 'DUMDEBUG' in os.environ:
print('DEBUG ---------------->')
PP.pprint(o)
print('---------------------->')
# Status codes
http_status_codes_map = {
100: "Continue",
101: "Switching Protocols",
102: "Processing",
200: "OK",
201: "Created",
202: "Accepted",
203: "Non-authoritative Information",
204: "No Content",
205: "Reset Content",
206: "Partial Content",
207: "Multi-Status",
208: "Already Reported",
226: "IM Used",
300: "Multiple Choices",
301: "Moved Permanently",
302: "Found",
303: "See Other",
304: "Not Modified",
305: "Use Proxy",
307: "Temporary Redirect",
308: "Permanent Redirect",
400: "Bad Request",
401: "Unauthorized",
402: "Payment Required",
403: "Forbidden",
404: "Not Found",
405: "Method Not Allowed",
406: "Not Acceptable",
407: "Proxy Authentication Required",
408: "Request Timeout",
409: "Conflict",
410: "Gone",
411: "Length Required",
412: "Precondition Failed",
413: "Payload Too Large",
414: "Request-URI Too Long",
415: "Unsupported Media Type",
416: "Requested Range Not Satisfiable",
417: "Expectation Failed",
418: "I'm a teapot",
421: "Misdirected Request",
422: "Unprocessable Entity",
423: "Locked",
424: "Failed Dependency",
426: "Upgrade Required",
428: "Precondition Required",
429: "Too Many Requests",
431: "Request Header Fields Too Large",
444: "Connection Closed Without Response",
451: "Unavailable For Legal Reasons",
499: "Client Closed Request",
500: "Internal Server Error",
501: "Not Implemented",
503: "Service Unavailable",
505: "HTTP Version Not Supported",
506: "Variant Also Negotiates",
507: "Insufficient Storage",
508: "Loop Detected",
510: "Not Extended",
511: "Network Authentication Required"
}
def status_map(code):
return str(int(code)) + ' ' + http_status_codes_map[int(code)]
# Grammar hence
# Defines some common symbols
newline = '\n'
request_start = Keyword('>')
response_start = Keyword('<')
comment = OneOrMore(Word('#') + Word(printables + ' '))
unicodePrintables = u''.join(unichr(c) for c in xrange(sys.maxunicode)
if not unichr(c).isspace())
# Defines HTTP verbs
verb_get = Keyword('GET')
verb_post = Keyword('POST')
verb_put = Keyword('PUT')
verb_delete = Keyword('DELETE')
verb_head = Keyword('HEAD')
verb = verb_get | verb_post | verb_put | verb_delete | verb_head
verb_line = request_start + verb + Optional(Suppress(',')) + Optional(delimitedList(verb))
# Defines relative url path
xalphas = Word(alphanums + '$-_@.&+!*"\'(),%/')
rel_path = request_start + xalphas
# Defines parameters
param = Keyword('param') | Keyword('PARAM')
param_maybe = Keyword('param_maybe') | Keyword('PARAM_MAYBE')
kw_param_is = Keyword('is') | Keyword('IS')
kw_param_like = Keyword('like') | Keyword('LIKE')
param_name = xalphas
param_val = xalphas
param_re = QuotedString(quoteChar='//')
param_S = request_start + (param ^ param_maybe) + param_name + kw_param_is + param_val
param_R = request_start + (param ^ param_maybe) + param_name + kw_param_like + param_re
header = request_start + Keyword('header') + Word(printables + ' ')
# Defines response values
delay = response_start + Keyword('delay') + Word(nums) # NOTE milliseconds
header_resp = response_start + Keyword('header') + Word(printables + ' ')
status = response_start + Keyword('status') + Word(nums)
body_resp = response_start + Keyword('body') + \
(Word(' ' + printables + unicodePrintables) ^ \
QuotedString(quoteChar='<<<', escQuote='<<<<<<', multiline=True))
# This echos the request body, used as an alt to '< body ...' above
echo_resp = response_start + Keyword('echo')
# Defines the stanza list
stanza_end = LineStart() + '.' + LineEnd()
# The parser
class DumdumParser(object):
class EchoFlag(object):
pass
def __init__(self, user_input):
self.S = {}
self.stanza = Group(
verb_line.setParseAction(self.process_verbs) + \
Optional(Suppress(comment))
) + \
Group(
rel_path.setParseAction(self.process_path) + \
Optional(Suppress(comment))
) + \
ZeroOrMore(
Group(header.setParseAction(self.process_header)) + \
Optional(Suppress(comment))
) + \
ZeroOrMore(
Group(
param_S.setParseAction(self.process_param) ^ \
param_R.setParseAction(self.process_param)
) + \
Optional(Suppress(comment))
) + \
ZeroOrMore(
Group(
delay.setParseAction(self.process_resp_delay) + \
Optional(Suppress(comment))
)
) + \
ZeroOrMore(
Group(
status.setParseAction(self.process_resp_status) + \
Optional(Suppress(comment))
)
) + \
ZeroOrMore(
Group(
header_resp.setParseAction(self.process_resp_header) + \
Optional(Suppress(comment))
)
) + \
ZeroOrMore(
Group(
body_resp.setParseAction(self.process_resp_body) ^ \
echo_resp.setParseAction(self.process_resp_echo)
) + \
Optional(Suppress(comment))
) + \
Suppress(stanza_end.setParseAction(self.save_stanza))
self.stanzas = OneOrMore(Group(
Optional(Suppress(comment)) + \
self.stanza + \
Optional(Suppress(comment))
))
# This is a top-down parser, but we register handlers on specific
# pattern matches, and using these "internal globals" allows us to keep
# state straight.
self.current_path = None
self.current_verbs = []
self.reqobj = None # stanza object from user input
self.respobj = None # stanza object from user input
dbg(user_input.decode('utf-8'))
# Parse the user data
self.stanzas.parseString(user_input.decode('utf-8'))
def process_verbs(self, tokens): # The VERB line ALWAYS starts a request stanza
self.reqobj = {}
# Defaults
self.respobj = {
'status': status_map(200),
'body':'',
}
self.current_verbs = tokens[1:]
for verb in self.current_verbs:
if verb not in self.S: self.S[verb] = {}
def process_path(self, tokens):
self.current_path = tokens[1]
for verb in self.current_verbs:
if self.current_path not in self.S[verb]:
self.S[verb][self.current_path] = []
def process_param(self, tokens):
p = tokens[2:]
if 'params' not in self.reqobj: self.reqobj['params'] = {}
if p[1] == 'like':
dbg("process_param() %s" % p)
self.reqobj['params'][p[0]] = re.compile(p[2])
else:
self.reqobj['params'][p[0]] = p[2]
def process_header(self, tokens):
def header_cgi_key(header):
h = header.upper().replace('-', '_')
if h != 'CONTENT_TYPE':
return 'HTTP_' + h # In CGI this precedes most headers
else:
return h
h = tokens[2:][0].split(': ')
if 'headers' not in self.reqobj: self.reqobj['headers'] = {}
self.reqobj['headers'][header_cgi_key(h[0])] = h[1]
def process_resp_status(self, tokens):
self.respobj['status'] = status_map(tokens[2])
def process_resp_delay(self, tokens):
self.respobj['delay'] = tokens[2]
def process_resp_header(self, tokens):
h = tokens[2:][0].split(': ')
if 'headers' not in self.respobj: self.respobj['headers'] = {}
self.respobj['headers'][h[0]] = h[1]
def process_resp_body(self, tokens):
b = tokens[2:][0]
self.respobj['body'] = b.strip() # TODO is this wise?
def process_resp_echo(self, tokens):
self.respobj['body'] = DumdumParser.EchoFlag()
def save_stanza(self, tokens):
if self.reqobj:
for verb in self.current_verbs:
if self.respobj: self.reqobj['response'] = self.respobj
self.S[verb][self.current_path].append(self.reqobj)
elif not self.reqobj and self.respobj:
self.reqobj = { 'response': self.respobj }
for verb in self.current_verbs:
self.S[verb][self.current_path].append(self.reqobj)
# The server
class Dumdum(object):
def __init__(self, user_stanzas):
self.user_stanzas = user_stanzas
self.parser = DumdumParser(user_stanzas)
self.Stanzas = self.parser.S
def server(self, env, start_response):
# Helper functions hence
def bad_req(msg="Sorry I couldn't help."):
status = '400 Bad Request' # HTTP Status
headers = [('Content-type', 'text/plain')] # HTTP Headers
start_response(status, headers)
return [msg]
def flatten_json(y):
delim='.'
out = {}
def flatten(x, name=''):
if type(x) is dict:
for a in x:
flatten(x[a], name + a + delim)
elif type(x) is list:
i = 0
for a in x:
flatten(a, name)
i += 1
else:
nam = name[:-len(delim)]
if nam not in out:
out[nam] = [x]
else:
out[nam].append(x)
flatten(y)
return out
# Handler hence
# The environment variable CONTENT_LENGTH may be empty or missing
try:
request_body_size = int(env.get('CONTENT_LENGTH', 0))
except (ValueError):
request_body_size = 0
try:
request_body = env['wsgi.input'].read(request_body_size)
except Exception:
pass
verb = env['REQUEST_METHOD']
url = urlparse(env['PATH_INFO'])
logger.info(
"\nCGI ENV: %s\n\n%s %s\n\n%s\n\n" %
(PP.pformat(env), verb, url.path, request_body))
if verb in self.Stanzas and url.path in self.Stanzas[verb]:
for curr_Stz in self.Stanzas[verb][url.path]: # check every stanza under this path
is_json = False
match = True
# compare headers
if 'headers' in curr_Stz:
for h in curr_Stz['headers']:
sh = curr_Stz['headers']
if h in env and env[h] == sh[h]:
if h == 'CONTENT_TYPE' and sh[h].lower() == 'application/json':
is_json = True
else:
match = False
break
# compare params
if match:
sp = None
if 'params' in curr_Stz: sp = curr_Stz['params']
dbg('Stanza params=%s' % sp)
if is_json and request_body and sp:
try:
j_rb = json.loads(request_body)
fj_rb = flatten_json(j_rb)
dbg(json.dumps(fj_rb, indent=2,
sort_keys=True))
except ValueError:
return bad_req("Error parsing: %s" % request_body)
for szparam in sp:
dbg('szparam=%s match %s' % (szparam, match))
if match == False: break
if szparam not in fj_rb:
match = False
break
else:
# Check all provided values from input, and if
# one of them matches, then
matchone = False
for v in fj_rb[szparam]:
dbg('v=%s szparam=%s' % (v, sp[szparam]))
if isinstance(sp[szparam], re._pattern_type):
if sp[szparam].search(v):
dbg('Match! regex')
matchone = True
break
else:
if v == sp[szparam]:
dbg('Match! exact')
matchone = True
break
match = matchone
elif sp:
if 'QUERY_STRING' in env and env['QUERY_STRING'] != '':
qs = parse_qs(env['QUERY_STRING'])
elif 'wsgi.input' in env:
# TODO assumes urlencode form params...
qs = parse_qs(request_body)
print qs
print sp
for szparam in sp:
dbg('szparam=%s match %s' % (szparam, match))
if match == False: break
if szparam not in qs:
match = False
break
else:
matchone = False
for v in qs[szparam]:
dbg('v=%s szparam=%s' % (v, sp[szparam]))
if isinstance(sp[szparam], re._pattern_type):
print '....?'
print sp[szparam].search(v)
if sp[szparam].search(v):
dbg('Match! regex')
matchone = True
break
else:
if v == sp[szparam]:
dbg('Match! exact')
matchone = True
break
match = matchone
if match:
if 'response' in curr_Stz:
resp = curr_Stz['response']
if 'delay' in resp:
time.sleep(float(resp['delay'])/1000.0)
status = resp['status']
hdrs = []
if 'headers' in resp:
for h in resp['headers']:
hdrs.append( (str(h),
str(resp['headers'][h])) )
start_response(status, hdrs)
if type(resp['body']) is DumdumParser.EchoFlag:
return request_body
else:
return [resp['body'].encode('utf-8')]
# We matched nothing
return bad_req()
if __name__ == "__main__":
import argparse
from wsgiref.simple_server import make_server
def read_from_stdin():
stz = ''
for line in sys.stdin:
stz += line
return stz
parser = argparse.ArgumentParser()
parser.add_argument('--port', help='set port for server (default 8001)')
parser.add_argument('--file', help='file containing dumdum stanzas')
parser.add_argument('--verbose', help='dump request and response info',
action='store_true')
args = parser.parse_args()
if args.verbose:
logging.basicConfig(stream=sys.stderr, level=logging.INFO)
else:
logging.basicConfig(stream=sys.stderr, level=logging.WARNING)
if not args.file:
user_stanza = read_from_stdin()
else:
with open(args.file, 'r') as f:
user_stanza = f.read()
dumdum = Dumdum(user_stanza)
port = args.port or 8001
srv = make_server('', int(port), dumdum.server)
try:
srv.serve_forever()
except KeyboardInterrupt:
print('\nBye.')