require 'socket' require 'ipaddr' require 'excon' require 'rate_limiter' require 'url_helper' # Determine the final endpoint for a Web URI, following redirects class FinalDestination def self.clear_https_cache!(domain) key = redis_https_key(domain) $redis.without_namespace.del(key) end def self.cache_https_domain(domain) key = redis_https_key(domain) $redis.without_namespace.setex(key, "1", 1.day.to_i).present? end def self.is_https_domain?(domain) key = redis_https_key(domain) $redis.without_namespace.get(key).present? end def self.redis_https_key(domain) "HTTPS_DOMAIN_#{domain}" end attr_reader :status, :cookie, :status_code, :ignored def initialize(url, opts = nil) @url = url @uri = uri(escape_url) if @url @opts = opts || {} @force_get_hosts = @opts[:force_get_hosts] || [] @preserve_fragment_url_hosts = @opts[:preserve_fragment_url_hosts] || [] @opts[:max_redirects] ||= 5 @opts[:lookup_ip] ||= lambda { |host| FinalDestination.lookup_ip(host) } @ignored = @opts[:ignore_hostnames] || [] ignore_redirects = [Discourse.base_url_no_prefix] if @opts[:ignore_redirects] ignore_redirects.concat(@opts[:ignore_redirects]) end ignore_redirects.each do |ignore_redirect| ignore_redirect = uri(ignore_redirect) if ignore_redirect.present? && ignore_redirect.hostname @ignored << ignore_redirect.hostname end end @limit = @opts[:max_redirects] @status = :ready @http_verb = @force_get_hosts.any? { |host| hostname_matches?(host) } ? :get : :head @cookie = nil @limited_ips = [] @verbose = @opts[:verbose] || false @timeout = @opts[:timeout] || nil @preserve_fragment_url = @preserve_fragment_url_hosts.any? { |host| hostname_matches?(host) } end def self.connection_timeout 20 end def timeout @timeout || FinalDestination.connection_timeout end def redirected? @limit < @opts[:max_redirects] end def request_headers result = { "User-Agent" => "Mozilla/5.0 (Windows NT 6.2; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36", "Accept" => "*/*", "Host" => @uri.hostname } result['Cookie'] = @cookie if @cookie result end def small_get(request_headers) status_code, response_headers = nil catch(:done) do Net::HTTP.start(@uri.host, @uri.port, use_ssl: @uri.is_a?(URI::HTTPS)) do |http| http.open_timeout = timeout http.read_timeout = timeout http.request_get(@uri.request_uri, request_headers) do |resp| status_code = resp.code.to_i response_headers = resp.to_hash # see: https://bugs.ruby-lang.org/issues/15624 # if we allow response to return then body will be read # got to abort without reading body throw :done end end end [status_code, response_headers] end # this is a new interface for simply getting # N bytes accounting for all internal logic def get(uri = @uri, redirects = @limit, extra_headers: {}, &blk) raise "Must specify block" unless block_given? if uri && uri.port == 80 && FinalDestination.is_https_domain?(uri.hostname) uri.scheme = "https" uri = URI(uri.to_s) end return nil unless validate_uri result, (location, cookie) = safe_get(uri, &blk) if result == :redirect && (redirects == 0 || !location) return nil end if result == :redirect old_port = uri.port location = "#{uri.scheme}://#{uri.host}#{location}" if location[0] == "/" uri = uri(location) # https redirect, so just cache that whole new domain is https if old_port == 80 && uri&.port == 443 && (URI::HTTPS === uri) FinalDestination.cache_https_domain(uri.hostname) end return nil if !uri extra = nil extra = { 'Cookie' => cookie } if cookie get(uri, redirects - 1, extra_headers: extra, &blk) elsif result == :ok uri.to_s else nil end end def resolve if @uri && @uri.port == 80 && FinalDestination.is_https_domain?(@uri.hostname) @uri.scheme = "https" @uri = URI(@uri.to_s) end if @limit < 0 @status = :too_many_redirects log(:warn, "FinalDestination could not resolve URL (too many redirects): #{@uri}") if @verbose return nil end unless validate_uri log(:warn, "FinalDestination could not resolve URL (invalid URI): #{@uri}") if @verbose return nil end @ignored.each do |host| if @uri&.hostname&.match?(host) @status = :resolved return @uri end end headers = request_headers response = Excon.public_send(@http_verb, @uri.to_s, read_timeout: timeout, headers: headers ) location = nil response_headers = nil response_status = response.status.to_i case response.status when 200 @status = :resolved return @uri when 400, 405, 406, 409, 501 response_status, small_headers = small_get(request_headers) if response_status == 200 @status = :resolved return @uri end response_headers = {} if cookie_val = small_headers['set-cookie'] response_headers[:cookies] = cookie_val end if location_val = small_headers['location'] response_headers[:location] = location_val.join end end unless response_headers response_headers = { cookies: response.data[:cookies] || response.headers[:"set-cookie"], location: response.headers[:location] } end if (300..399).include?(response_status) location = response_headers[:location] end if cookies = response_headers[:cookies] @cookie = Array.wrap(cookies).map { |c| c.split(';').first.strip }.join('; ') end if location old_port = @uri.port location = "#{location}##{@uri.fragment}" if @preserve_fragment_url && @uri.fragment.present? location = "#{@uri.scheme}://#{@uri.host}#{location}" if location[0] == "/" @uri = uri(location) @limit -= 1 # https redirect, so just cache that whole new domain is https if old_port == 80 && @uri.port == 443 && (URI::HTTPS === @uri) FinalDestination.cache_https_domain(@uri.hostname) end return resolve end # this is weird an exception seems better @status = :failure @status_code = response.status log(:warn, "FinalDestination could not resolve URL (status #{response.status}): #{@uri}") if @verbose nil rescue Excon::Errors::Timeout log(:warn, "FinalDestination could not resolve URL (timeout): #{@uri}") if @verbose nil end def validate_uri validate_uri_format && is_dest_valid? end def validate_uri_format return false unless @uri return false unless ['https', 'http'].include?(@uri.scheme) return false if @uri.scheme == 'http' && @uri.port != 80 return false if @uri.scheme == 'https' && @uri.port != 443 # Disallow IP based crawling (IPAddr.new(@uri.hostname) rescue nil).nil? end def hostname_matches?(url) url = uri(url) @uri && url.present? && @uri.hostname == url&.hostname end def is_dest_valid? return false unless @uri && @uri.host # Whitelisted hosts return true if hostname_matches?(SiteSetting.Upload.s3_cdn_url) || hostname_matches?(GlobalSetting.try(:cdn_url)) || hostname_matches?(Discourse.base_url_no_prefix) if SiteSetting.whitelist_internal_hosts.present? return true if SiteSetting.whitelist_internal_hosts.split("|").any? { |h| h.downcase == @uri.hostname.downcase } end address_s = @opts[:lookup_ip].call(@uri.hostname) return false unless address_s address = IPAddr.new(address_s) if private_ranges.any? { |r| r === address } @status = :invalid_address return false end # Rate limit how often this IP can be crawled if !@opts[:skip_rate_limit] && !@limited_ips.include?(address) @limited_ips << address RateLimiter.new(nil, "crawl-destination-ip:#{address_s}", 1000, 1.hour).performed! end true rescue RateLimiter::LimitExceeded false end def escape_url UrlHelper.escape_uri( CGI.unescapeHTML(@url), Regexp.new("[^#{URI::PATTERN::UNRESERVED}#{URI::PATTERN::RESERVED}#]") ) end def private_ranges FinalDestination.standard_private_ranges + SiteSetting.blacklist_ip_blocks.split('|').map { |r| IPAddr.new(r) rescue nil }.compact end def log(log_level, message) return if @status_code == 404 Rails.logger.public_send( log_level, "#{RailsMultisite::ConnectionManagement.current_db}: #{message}" ) end def self.standard_private_ranges @private_ranges ||= [ IPAddr.new('0.0.0.0/8'), IPAddr.new('127.0.0.1'), IPAddr.new('172.16.0.0/12'), IPAddr.new('192.168.0.0/16'), IPAddr.new('10.0.0.0/8'), IPAddr.new('fc00::/7') ] end def self.lookup_ip(host) if Rails.env.test? "1.1.1.1" else IPSocket::getaddress(host) end rescue SocketError nil end protected def safe_get(uri) result = nil unsafe_close = false safe_session(uri) do |http| headers = request_headers.merge( 'Accept-Encoding' => 'gzip', 'Host' => uri.host ) req = Net::HTTP::Get.new(uri.request_uri, headers) http.request(req) do |resp| if Net::HTTPRedirection === resp result = :redirect, [resp['location'], resp['Set-Cookie']] end if Net::HTTPSuccess === resp resp.decode_content = true resp.read_body do |chunk| read_next = true catch(:done) do if read_next read_next = false yield resp, chunk, uri read_next = true end end # no clean way of finishing abruptly cause # response likes reading till the end if !read_next unsafe_close = true http.finish raise StandardError end end result = :ok else catch(:done) do yield resp, nil, nil end end end end result rescue StandardError unsafe_close ? :ok : raise end def safe_session(uri) Net::HTTP.start(uri.host, uri.port, use_ssl: (uri.scheme == "https")) do |http| http.read_timeout = timeout http.open_timeout = timeout yield http end end private def uri(location) begin URI.parse(location) rescue URI::Error end end end