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# Copyright, 2017, by Samuel G. D. Williams. <http://www.codeotaku.com>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.
require_relative 'client'
require_relative 'endpoint'
require_relative 'reference'
require 'protocol/http/middleware'
require 'protocol/http/body/rewindable'
module Async
module HTTP
class TooManyRedirects < StandardError
end
# A client wrapper which transparently handles both relative and absolute redirects to a given maximum number of hops.
#
# The best reference for these semantics is defined by the [Fetch specification](https://fetch.spec.whatwg.org/#http-redirect-fetch).
#
# | Redirect using GET | Permanent | Temporary |
# |:-----------------------------------------:|:---------:|:---------:|
# | Allowed | 301 | 302 |
# | Preserve original method | 308 | 307 |
#
# For the specific details of the redirect handling, see:
# - <https://datatracker.ietf.org/doc/html/rfc7231#section-6-4-2> 301 Moved Permanently.
# - <https://datatracker.ietf.org/doc/html/rfc7231#section-6-4-3> 302 Found.
# - <https://datatracker.ietf.org/doc/html/rfc7538 308 Permanent Redirect.
# - <https://datatracker.ietf.org/doc/html/rfc7231#section-6-4-7> 307 Temporary Redirect.
#
class RelativeLocation < ::Protocol::HTTP::Middleware
# Header keys which should be deleted when changing a request from a POST to a GET as defined by <https://fetch.spec.whatwg.org/#request-body-header-name>.
PROHIBITED_GET_HEADERS = [
'content-encoding',
'content-language',
'content-location',
'content-type',
]
# maximum_hops is the max number of redirects. Set to 0 to allow 1 request with no redirects.
def initialize(app, maximum_hops = 3)
super(app)
@maximum_hops = maximum_hops
end
# The maximum number of hops which will limit the number of redirects until an error is thrown.
attr :maximum_hops
def redirect_with_get?(request, response)
# We only want to switch to GET if the request method is something other than get, e.g. POST.
if request.method != GET
# According to the RFC, we should only switch to GET if the response is a 301 or 302:
return response.status == 301 || response.status == 302
end
end
def call(request)
# We don't want to follow redirects for HEAD requests:
return super if request.head?
if body = request.body
# We need to cache the body as it might be submitted multiple times if we get a response status of 307 or 308:
body = ::Protocol::HTTP::Body::Rewindable.new(body)
request.body = body
end
hops = 0
while hops <= @maximum_hops
response = super(request)
if response.redirection?
hops += 1
# Get the redirect location:
unless location = response.headers['location']
return response
end
response.finish
uri = URI.parse(location)
if uri.absolute?
return response
else
request.path = Reference[request.path] + location
end
if request.method == GET or response.preserve_method?
# We (might) need to rewind the body so that it can be submitted again:
body&.rewind
else
# We are changing the method to GET:
request.method = GET
# Clear the request body:
request.finish
body = nil
# Remove any headers which are not allowed in a GET request:
PROHIBITED_GET_HEADERS.each do |header|
request.headers.delete(header)
end
end
else
return response
end
end
raise TooManyRedirects, "Redirected #{hops} times, exceeded maximum!"
end
end
end
end
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