536 lines
15 KiB
Ruby
536 lines
15 KiB
Ruby
# frozen_string_literal: true
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require 'socket'
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require 'ipaddr'
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require 'excon'
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require 'rate_limiter'
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require 'url_helper'
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# Determine the final endpoint for a Web URI, following redirects
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class FinalDestination
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MAX_REQUEST_TIME_SECONDS = 10
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MAX_REQUEST_SIZE_BYTES = 5_242_880 # 1024 * 1024 * 5
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def self.clear_https_cache!(domain)
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key = redis_https_key(domain)
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Discourse.redis.without_namespace.del(key)
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end
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def self.cache_https_domain(domain)
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key = redis_https_key(domain)
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Discourse.redis.without_namespace.setex(key, 1.day.to_i, "1")
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end
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def self.is_https_domain?(domain)
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key = redis_https_key(domain)
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Discourse.redis.without_namespace.get(key).present?
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end
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def self.redis_https_key(domain)
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"HTTPS_DOMAIN_#{domain}"
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end
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DEFAULT_USER_AGENT = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0 Safari/605.1.15"
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attr_reader :status, :cookie, :status_code, :content_type, :ignored
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def initialize(url, opts = nil)
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@url = url
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@uri = uri(normalized_url) if @url
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@opts = opts || {}
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@force_get_hosts = @opts[:force_get_hosts] || []
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@preserve_fragment_url_hosts = @opts[:preserve_fragment_url_hosts] || []
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@force_custom_user_agent_hosts = @opts[:force_custom_user_agent_hosts] || []
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@default_user_agent = @opts[:default_user_agent] || DEFAULT_USER_AGENT
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@opts[:max_redirects] ||= 5
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@https_redirect_ignore_limit = @opts[:initial_https_redirect_ignore_limit]
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@max_redirects = @opts[:max_redirects]
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@limit = @max_redirects
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@ignored = []
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if @limit > 0
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ignore_redirects = [Discourse.base_url_no_prefix]
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if @opts[:ignore_redirects]
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ignore_redirects.concat(@opts[:ignore_redirects])
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end
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ignore_redirects.each do |ignore_redirect|
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ignore_redirect = uri(ignore_redirect)
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if ignore_redirect.present? && ignore_redirect.hostname
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@ignored << ignore_redirect.hostname
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end
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end
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end
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@status = :ready
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@follow_canonical = @opts[:follow_canonical]
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@http_verb = @opts[:http_verb] || http_verb(@force_get_hosts, @follow_canonical)
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@cookie = nil
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@limited_ips = []
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@verbose = @opts[:verbose] || false
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@timeout = @opts[:timeout] || nil
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@preserve_fragment_url = @preserve_fragment_url_hosts.any? { |host| hostname_matches?(host) }
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@validate_uri = @opts.fetch(:validate_uri) { true }
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@user_agent = @force_custom_user_agent_hosts.any? { |host| hostname_matches?(host) } ? Onebox.options.user_agent : @default_user_agent
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@stop_at_blocked_pages = @opts[:stop_at_blocked_pages]
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end
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def self.connection_timeout
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20
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end
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def self.resolve(url, opts = nil)
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new(url, opts).resolve
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end
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def http_verb(force_get_hosts, follow_canonical)
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if follow_canonical || force_get_hosts.any? { |host| hostname_matches?(host) }
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:get
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else
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:head
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end
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end
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def timeout
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@timeout || FinalDestination.connection_timeout
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end
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def redirected?
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@limit < @max_redirects
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end
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def request_headers
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result = {
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"User-Agent" => @user_agent,
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"Accept" => "*/*",
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"Accept-Language" => "*",
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"Host" => @uri.hostname
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}
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result['Cookie'] = @cookie if @cookie
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result
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end
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def small_get(request_headers)
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status_code, response_headers = nil
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catch(:done) do
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FinalDestination::HTTP.start(@uri.host, @uri.port, use_ssl: @uri.is_a?(URI::HTTPS), open_timeout: timeout) do |http|
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http.read_timeout = timeout
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http.request_get(@uri.request_uri, request_headers) do |resp|
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status_code = resp.code.to_i
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response_headers = resp.to_hash
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# see: https://bugs.ruby-lang.org/issues/15624
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# if we allow response to return then body will be read
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# got to abort without reading body
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throw :done
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end
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end
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end
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[status_code, response_headers]
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end
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# this is a new interface for simply getting
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# N bytes accounting for all internal logic
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def get(redirects = @limit, extra_headers: {}, &blk)
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raise "Must specify block" unless block_given?
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if @uri && @uri.port == 80 && FinalDestination.is_https_domain?(@uri.hostname)
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@uri.scheme = "https"
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@uri = URI(@uri.to_s)
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end
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return if !validate_uri
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return if @stop_at_blocked_pages && blocked_domain?(@uri)
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result, headers_subset = safe_get(@uri, &blk)
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return if !result
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cookie = headers_subset.set_cookie
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location = headers_subset.location
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if result == :redirect
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return if !location
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old_uri = @uri
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location = "#{@uri.scheme}://#{@uri.host}#{location}" if location[0] == "/"
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@uri = uri(location)
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if @uri && redirects == @max_redirects && @https_redirect_ignore_limit && same_uri_but_https?(old_uri, @uri)
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redirects += 1
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@https_redirect_ignore_limit = false
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end
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return if redirects == 0
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# https redirect, so just cache that whole new domain is https
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if old_uri.port == 80 && @uri&.port == 443 && (URI::HTTPS === @uri)
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FinalDestination.cache_https_domain(@uri.hostname)
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end
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return if !@uri
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extra = nil
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extra = { 'Cookie' => cookie } if cookie
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get(redirects - 1, extra_headers: extra, &blk)
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elsif result == :ok
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@uri.to_s
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else
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nil
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end
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end
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def resolve
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if @uri && @uri.port == 80 && FinalDestination.is_https_domain?(@uri.hostname)
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@uri.scheme = "https"
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@uri = URI(@uri.to_s)
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end
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if @limit < 0
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@status = :too_many_redirects
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log(:warn, "FinalDestination could not resolve URL (too many redirects): #{@uri}")
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return
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end
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unless validate_uri
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@status = :invalid_address
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log(:warn, "FinalDestination could not resolve URL (invalid URI): #{@uri}")
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return
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end
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@ignored.each do |host|
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if @uri&.hostname&.match?(host)
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@status = :resolved
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return @uri
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end
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end
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if Oneboxer.cached_response_body_exists?(@uri.to_s)
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@status = :resolved
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return @uri
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end
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headers = request_headers
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middlewares = Excon.defaults[:middlewares].dup
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middlewares << Excon::Middleware::Decompress if @http_verb == :get
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request_start_time = Time.now
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response_body = +""
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request_validator = lambda do |chunk, _remaining_bytes, _total_bytes|
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response_body << chunk
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raise Excon::Errors::ExpectationFailed.new("response size too big: #{@uri.to_s}") if response_body.bytesize > MAX_REQUEST_SIZE_BYTES
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raise Excon::Errors::ExpectationFailed.new("connect timeout reached: #{@uri.to_s}") if Time.now - request_start_time > MAX_REQUEST_TIME_SECONDS
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end
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# This technique will only use the first resolved IP
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# TODO: Can we standardise this by using FinalDestination::HTTP?
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begin
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resolved_ip = SSRFDetector.lookup_and_filter_ips(@uri.hostname).first
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rescue SSRFDetector::DisallowedIpError, SocketError, Timeout::Error
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@status = :invalid_address
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return
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end
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request_uri = @uri.dup
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request_uri.hostname = resolved_ip unless Rails.env.test? # WebMock doesn't understand the IP-based requests
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response = Excon.public_send(@http_verb,
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request_uri.to_s,
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read_timeout: timeout,
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connect_timeout: timeout,
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headers: { "Host" => @uri.hostname }.merge(headers),
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middlewares: middlewares,
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response_block: request_validator,
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ssl_verify_peer_host: @uri.hostname
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)
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if @stop_at_blocked_pages
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if blocked_domain?(@uri) || response.headers['Discourse-No-Onebox'] == "1"
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@status = :blocked_page
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return
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end
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end
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location = nil
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response_headers = nil
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response_status = response.status.to_i
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case response.status
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when 200
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# Cache body of successful `get` requests
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if @http_verb == :get
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if Oneboxer.cache_response_body?(@uri)
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Oneboxer.cache_response_body(@uri.to_s, response_body)
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end
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end
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if @follow_canonical
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next_url = fetch_canonical_url(response_body)
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if next_url.to_s.present? && next_url != @uri
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@follow_canonical = false
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@uri = next_url
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@http_verb = http_verb(@force_get_hosts, @follow_canonical)
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return resolve
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end
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end
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@content_type = response.headers['Content-Type'] if response.headers.has_key?('Content-Type')
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@status = :resolved
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return @uri
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when 103, 400, 405, 406, 409, 500, 501
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response_status, small_headers = small_get(request_headers)
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if @stop_at_blocked_pages
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# this may seem weird, but the #to_hash method of the response object
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# of ruby's net/http lib returns a hash where each value is an array.
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# small_headers here is like that so our no onebox header value is an
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# array if it's set. Also the hash keys are always lower-cased.
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dont_onebox = small_headers["discourse-no-onebox"]&.join("") == "1"
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if dont_onebox || blocked_domain?(@uri)
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@status = :blocked_page
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return
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end
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end
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if response_status == 200
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@status = :resolved
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return @uri
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end
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response_headers = {}
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if cookie_val = small_headers['set-cookie']
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response_headers[:cookies] = cookie_val
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end
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if location_val = small_headers['location']
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response_headers[:location] = location_val.join
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end
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end
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unless response_headers
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response_headers = {
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cookies: response.data[:cookies] || response.headers[:"set-cookie"],
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location: response.headers[:location]
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}
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end
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if (300..399).include?(response_status)
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location = response_headers[:location]
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end
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if cookies = response_headers[:cookies]
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@cookie = Array.wrap(cookies).map { |c| c.split(';').first.strip }.join('; ')
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end
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if location
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redirect_uri = uri(location)
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if @uri.host == redirect_uri.host && (redirect_uri.path =~ /\/login/ || redirect_uri.path =~ /\/session/)
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@status = :resolved
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return @uri
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end
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old_uri = @uri
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location = "#{location}##{@uri.fragment}" if @preserve_fragment_url && @uri.fragment.present?
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location = "#{@uri.scheme}://#{@uri.host}#{location}" if location[0] == "/"
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@uri = uri(location)
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if @uri && @limit == @max_redirects && @https_redirect_ignore_limit && same_uri_but_https?(old_uri, @uri)
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@limit += 1
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@https_redirect_ignore_limit = false
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end
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@limit -= 1
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# https redirect, so just cache that whole new domain is https
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if old_uri.port == 80 && @uri&.port == 443 && (URI::HTTPS === @uri)
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FinalDestination.cache_https_domain(@uri.hostname)
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end
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return resolve
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end
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# this is weird an exception seems better
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@status = :failure
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@status_code = response.status
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log(:warn, "FinalDestination could not resolve URL (status #{response.status}): #{@uri}")
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nil
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rescue Excon::Errors::Timeout
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log(:warn, "FinalDestination could not resolve URL (timeout): #{@uri}")
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nil
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end
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def skip_validations?
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!@validate_uri
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end
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def validate_uri
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skip_validations? || validate_uri_format
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end
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def validate_uri_format
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return false unless @uri && @uri.host
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return false unless ['https', 'http'].include?(@uri.scheme)
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return false if @uri.scheme == 'http' && @uri.port != 80
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return false if @uri.scheme == 'https' && @uri.port != 443
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# Disallow IP based crawling
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(IPAddr.new(@uri.hostname) rescue nil).nil?
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end
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def hostname
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@uri.hostname
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end
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def hostname_matches?(url)
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url = uri(url)
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if @uri&.hostname.present? && url&.hostname.present?
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hostname_parts = url.hostname.split('.')
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has_wildcard = hostname_parts.first == '*'
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if has_wildcard
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@uri.hostname.end_with?(hostname_parts[1..-1].join('.'))
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else
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@uri.hostname == url.hostname
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end
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end
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end
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def normalized_url
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UrlHelper.normalized_encode(@url)
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end
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def log(log_level, message)
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return unless @verbose
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return if @status_code == 404
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Rails.logger.public_send(
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log_level,
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"#{RailsMultisite::ConnectionManagement.current_db}: #{message}"
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)
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end
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protected
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def safe_get(uri)
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result = nil
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unsafe_close = false
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headers_subset = Struct.new(:location, :set_cookie).new
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safe_session(uri) do |http|
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headers = request_headers.merge(
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'Accept-Encoding' => 'gzip',
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'Host' => uri.host
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)
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req = FinalDestination::HTTP::Get.new(uri.request_uri, headers)
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http.request(req) do |resp|
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headers_subset.set_cookie = resp['Set-Cookie']
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if @stop_at_blocked_pages
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dont_onebox = resp["Discourse-No-Onebox"] == "1"
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if dont_onebox
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result = :blocked, headers_subset
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next
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end
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end
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if Net::HTTPRedirection === resp
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headers_subset.location = resp['location']
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result = :redirect, headers_subset
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end
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if Net::HTTPSuccess === resp
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resp.decode_content = true
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resp.read_body do |chunk|
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read_next = true
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catch(:done) do
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if read_next
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read_next = false
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yield resp, chunk, uri
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read_next = true
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end
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end
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# no clean way of finishing abruptly cause
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# response likes reading till the end
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if !read_next
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unsafe_close = true
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http.finish
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raise StandardError
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end
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end
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result = :ok, headers_subset
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else
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catch(:done) do
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yield resp, nil, nil
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end
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end
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end
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end
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result
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rescue Timeout::Error
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log(:warn, "FinalDestination could not resolve URL (timeout): #{@uri}")
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nil
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rescue OpenSSL::SSL::SSLError => exception
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log(:warn, "An error with SSL occurred: #{@uri} #{exception.message}")
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nil
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rescue StandardError
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unsafe_close ? [:ok, headers_subset] : raise
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end
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def safe_session(uri)
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FinalDestination::HTTP.start(uri.host, uri.port, use_ssl: (uri.scheme == "https"), open_timeout: timeout) do |http|
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http.read_timeout = timeout
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yield http
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end
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end
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private
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def uri(location)
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begin
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URI.parse(location)
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rescue URI::Error
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end
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end
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def fetch_canonical_url(body)
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return if body.blank?
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canonical_element = Nokogiri::HTML5(body).at("link[rel='canonical']")
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return if canonical_element.nil?
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canonical_uri = uri(canonical_element['href'])
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return if canonical_uri.blank?
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return canonical_uri if canonical_uri.host.present?
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parts = [@uri.host, canonical_uri.to_s]
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complete_url = canonical_uri.to_s.starts_with?('/') ? parts.join('') : parts.join('/')
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complete_url = "#{@uri.scheme}://#{complete_url}" if @uri.scheme
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uri(complete_url)
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end
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def blocked_domain?(uri)
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Onebox::DomainChecker.is_blocked?(uri.hostname)
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end
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def same_uri_but_https?(before, after)
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before = before.to_s
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after = after.to_s
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before.start_with?("http://") &&
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after.start_with?("https://") &&
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before.sub("http://", "") == after.sub("https://", "")
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end
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end
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