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"""Utility functions shared across multiple endpoints."""
from collections import namedtuple
from urllib.parse import unquote_plus, urlparse
def headers_to_ascii(headers):
"""Converts a header map with binary values to one with ASCII values.
Takes a map of header names to list of values that are all binary strings
and returns an otherwise identical map where keys and values have both been
converted to ASCII strings.
Args:
headers: header map from binary key to binary value
Returns header map from ASCII string key to ASCII string value
"""
header_map = {}
for pair in headers.items():
values = []
for value in pair[1]:
values.append(value.decode("ASCII"))
header_map[pair[0].decode("ASCII")] = values
return header_map
def handle_cors_headers_and_preflight(request, response):
"""Applies CORS logic common to many entrypoints.
Args:
request: the wptserve Request that was passed to main
response: the wptserve Response that was passed to main
Returns True if the request is a CORS preflight, which is entirely handled by
this function, so that the calling function should immediately return.
"""
# Append CORS headers if needed
if b"origin" in request.headers:
response.headers.set(b"Access-Control-Allow-Origin",
request.headers.get(b"origin"))
if b"credentials" in request.headers:
response.headers.set(b"Access-Control-Allow-Credentials",
request.headers.get(b"credentials"))
# Handle CORS preflight requests.
if not request.method == u"OPTIONS":
return False
if not b"Access-Control-Request-Method" in request.headers:
response.status = (400, b"Bad Request")
response.headers.set(b"Content-Type", b"text/plain")
response.content = "Failed to get access-control-request-method in preflight!"
return True
if not b"Access-Control-Request-Headers" in request.headers:
response.status = (400, b"Bad Request")
response.headers.set(b"Content-Type", b"text/plain")
response.content = "Failed to get access-control-request-headers in preflight!"
return True
response.headers.set(b"Access-Control-Allow-Methods",
request.headers[b"Access-Control-Request-Method"])
response.headers.set(b"Access-Control-Allow-Headers",
request.headers[b"Access-Control-Request-Headers"])
response.status = (204, b"No Content")
return True
def decode_trusted_scoring_signals_params(request):
"""Decodes query parameters to trusted query params handler.
Args:
request: the wptserve Request that was passed to main
If successful, returns a named tuple TrustedScoringSignalsParams decoding the
various expected query fields, as a hostname, plus a field urlLists which is a list of
{type: <render URL type>, urls: <render URL list>} pairs, where <render URL type> is
one of the two render URL dictionary keys used in the response ("renderURLs" or
"adComponentRenderURLs"). May be of length 1 or 2, depending on whether there
are any component URLs.
On failure, throws a ValueError with a message.
"""
TrustedScoringSignalsParams = namedtuple(
'TrustedScoringSignalsParams', ['hostname', 'urlLists'])
hostname = None
renderUrls = None
adComponentRenderURLs = None
urlLists = []
# Manually parse query params. Can't use request.GET because it unescapes as well as splitting,
# and commas mean very different things from escaped commas.
for param in request.url_parts.query.split("&"):
pair = param.split("=", 1)
if len(pair) != 2:
raise ValueError("Bad query parameter: " + param)
# Browsers should escape query params consistently.
if "%20" in pair[1]:
raise ValueError("Query parameter should escape using '+': " + param)
# Hostname can't be empty. The empty string can be a key or interest group name, though.
if pair[0] == "hostname" and hostname == None and len(pair[1]) > 0:
hostname = pair[1]
continue
if pair[0] == "renderUrls" and renderUrls == None:
renderUrls = list(map(unquote_plus, pair[1].split(",")))
urlLists.append({"type":"renderURLs", "urls":renderUrls})
continue
if pair[0] == "adComponentRenderUrls" and adComponentRenderURLs == None:
adComponentRenderURLs = list(map(unquote_plus, pair[1].split(",")))
urlLists.append({"type":"adComponentRenderURLs", "urls":adComponentRenderURLs})
continue
raise ValueError("Unexpected query parameter: " + param)
# "hostname" and "renderUrls" are mandatory.
if not hostname:
raise ValueError("hostname missing")
if not renderUrls:
raise ValueError("renderUrls missing")
return TrustedScoringSignalsParams(hostname, urlLists)
def decode_render_url_signals_params(renderUrl):
"""Decodes signalsParams field encoded inside a renderURL.
Args: renderUrl to extract signalsParams from.
Returns an array of fields in signal params string.
"""
signalsParams = None
for param in urlparse(renderUrl).query.split("&"):
pair = param.split("=", 1)
if len(pair) != 2:
continue
if pair[0] == "signalsParams":
if signalsParams != None:
raise ValueError("renderUrl has multiple signalsParams: " + renderUrl)
signalsParams = pair[1]
if signalsParams is None:
return []
signalsParams = unquote_plus(signalsParams)
return signalsParams.split(",")