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Move Async::HTTP::RelativeLocation to Async::HTTP::Middleware::LocationRedirector. #174

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Aug 14, 2024
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Move Async::HTTP::RelativeLocation to Async::HTTP::Middleware::LocationRedirector. #174

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144 changes: 144 additions & 0 deletions lib/async/http/middleware/location_redirector.rb
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Original file line number Diff line number Diff line change
@@ -0,0 +1,144 @@
# frozen_string_literal: true

# Released under the MIT License.
# Copyright, 2018-2023, by Samuel Williams.
# Copyright, 2019-2020, by Brian Morearty.

require_relative '../reference'

require 'protocol/http/middleware'
require 'protocol/http/body/rewindable'

module Async
module HTTP
module Middleware
# A client wrapper which transparently handles redirects to a given maximum number of hops.
#
# The default implementation will only follow relative locations (i.e. those without a scheme) and will switch to GET if the original request was not a GET.
#
# 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 LocationRedirector < ::Protocol::HTTP::Middleware
class TooManyRedirects < StandardError
end

# 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

# Handle a redirect to a relative location.
#
# @parameter request [Protocol::HTTP::Request] The original request, which you can modify if you want to handle the redirect.
# @parameter location [String] The relative location to redirect to.
# @returns [Boolean] True if the redirect was handled, false if it was not.
def handle_redirect(request, location)
uri = URI.parse(location)

if uri.absolute?
return false
end

# Update the path of the request:
request.path = Reference[request.path] + location

# Follow the redirect:
return true
end

def call(request)
# We don't want to follow redirects for HEAD requests:
return super if request.head?

if body = request.body
if body.respond_to?(:rewind)
# The request body was already rewindable, so use it as is:
body = request.body
else
# The request body was not rewindable, and we might need to resubmit it if we get a response status of 307 or 308, so make it rewindable:
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These comments are really good!

body = ::Protocol::HTTP::Body::Rewindable.new(body)
request.body = body
end
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

unless handle_redirect(request, location)
return response
end

# Ensure the request (body) is finished and set to nil before we manipulate the request:
request.finish

if request.method == GET or response.preserve_method?
# We (might) need to rewind the body so that it can be submitted again:
body&.rewind
request.body = body
else
# We are changing the method to GET:
request.method = GET

# We will no longer be submitting the body:
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
end
136 changes: 5 additions & 131 deletions lib/async/http/relative_location.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -4,141 +4,15 @@
# Copyright, 2018-2023, by Samuel Williams.
# Copyright, 2019-2020, by Brian Morearty.

require_relative 'client'
require_relative 'endpoint'
require_relative 'reference'
require_relative 'middleware/location_redirector'

require 'protocol/http/middleware'
require 'protocol/http/body/rewindable'
warn "`Async::HTTP::RelativeLocation` is deprecated and will be removed in the next release. Please use `Async::HTTP::Middleware::LocationRedirector` instead.", uplevel: 1

module Async
module HTTP
class TooManyRedirects < StandardError
end

# A client wrapper which transparently handles redirects to a given maximum number of hops.
#
# The default implementation will only follow relative locations (i.e. those without a scheme) and will switch to GET if the original request was not a GET.
#
# 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

# Handle a redirect to a relative location.
#
# @parameter request [Protocol::HTTP::Request] The original request, which you can modify if you want to handle the redirect.
# @parameter location [String] The relative location to redirect to.
# @returns [Boolean] True if the redirect was handled, false if it was not.
def handle_redirect(request, location)
uri = URI.parse(location)

if uri.absolute?
return false
end

# Update the path of the request:
request.path = Reference[request.path] + location

# Follow the redirect:
return true
end

def call(request)
# We don't want to follow redirects for HEAD requests:
return super if request.head?

if body = request.body
if body.respond_to?(:rewind)
# The request body was already rewindable, so use it as is:
body = request.body
else
# The request body was not rewindable, and we might need to resubmit it if we get a response status of 307 or 308, so make it rewindable:
body = ::Protocol::HTTP::Body::Rewindable.new(body)
request.body = body
end
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

unless handle_redirect(request, location)
return response
end

# Ensure the request (body) is finished and set to nil before we manipulate the request:
request.finish

if request.method == GET or response.preserve_method?
# We (might) need to rewind the body so that it can be submitted again:
body&.rewind
request.body = body
else
# We are changing the method to GET:
request.method = GET

# We will no longer be submitting the body:
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
module Middleware
RelativeLocation = Middleware::LocationRedirector
TooManyRedirects = RelativeLocation::TooManyRedirects
end
end
end
6 changes: 3 additions & 3 deletions test/async/http/relative_location.rb → ...nc/http/middleware/location_redirector.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,12 @@
# Copyright, 2018-2023, by Samuel Williams.
# Copyright, 2019-2020, by Brian Morearty.

require 'async/http/relative_location'
require 'async/http/middleware/location_redirector'
require 'async/http/server'

require 'sus/fixtures/async/http'

describe Async::HTTP::RelativeLocation do
describe Async::HTTP::Middleware::LocationRedirector do
include Sus::Fixtures::Async::HTTP::ServerContext

let(:relative_location) {subject.new(@client, 1)}
Expand Down Expand Up @@ -49,7 +49,7 @@
it 'should fail with maximum redirects' do
expect do
response = relative_location.get('/home')
end.to raise_exception(Async::HTTP::TooManyRedirects, message: be =~ /maximum/)
end.to raise_exception(subject::TooManyRedirects, message: be =~ /maximum/)
end
end

Expand Down
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