/actionpack/lib/action_dispatch/middleware/remote_ip.rb
Ruby | 187 lines | 82 code | 18 blank | 87 comment | 5 complexity | d3980bdd110db51b61ae1562eeee8519 MD5 | raw file
- module ActionDispatch
- # This middleware calculates the IP address of the remote client that is
- # making the request. It does this by checking various headers that could
- # contain the address, and then picking the last-set address that is not
- # on the list of trusted IPs. This follows the precedent set by e.g.
- # {the Tomcat server}[https://issues.apache.org/bugzilla/show_bug.cgi?id=50453],
- # with {reasoning explained at length}[http://blog.gingerlime.com/2012/rails-ip-spoofing-vulnerabilities-and-protection]
- # by @gingerlime. A more detailed explanation of the algorithm is given
- # at GetIp#calculate_ip.
- #
- # Some Rack servers concatenate repeated headers, like {HTTP RFC 2616}[http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html#sec4.2]
- # requires. Some Rack servers simply drop preceding headers, and only report
- # the value that was {given in the last header}[http://andre.arko.net/2011/12/26/repeated-headers-and-ruby-web-servers].
- # If you are behind multiple proxy servers (like Nginx to HAProxy to Unicorn)
- # then you should test your Rack server to make sure your data is good.
- #
- # IF YOU DON'T USE A PROXY, THIS MAKES YOU VULNERABLE TO IP SPOOFING.
- # This middleware assumes that there is at least one proxy sitting around
- # and setting headers with the client's remote IP address. If you don't use
- # a proxy, because you are hosted on e.g. Heroku without SSL, any client can
- # claim to have any IP address by setting the X-Forwarded-For header. If you
- # care about that, then you need to explicitly drop or ignore those headers
- # sometime before this middleware runs.
- class RemoteIp
- class IpSpoofAttackError < StandardError; end
- # The default trusted IPs list simply includes IP addresses that are
- # guaranteed by the IP specification to be private addresses. Those will
- # not be the ultimate client IP in production, and so are discarded. See
- # http://en.wikipedia.org/wiki/Private_network for details.
- TRUSTED_PROXIES = %r{
- ^127\.0\.0\.1$ | # localhost IPv4
- ^::1$ | # localhost IPv6
- ^fc00: | # private IPv6 range fc00
- ^10\. | # private IPv4 range 10.x.x.x
- ^172\.(1[6-9]|2[0-9]|3[0-1])\.| # private IPv4 range 172.16.0.0 .. 172.31.255.255
- ^192\.168\. # private IPv4 range 192.168.x.x
- }x
- attr_reader :check_ip, :proxies
- # Create a new +RemoteIp+ middleware instance.
- #
- # The +check_ip_spoofing+ option is on by default. When on, an exception
- # is raised if it looks like the client is trying to lie about its own IP
- # address. It makes sense to turn off this check on sites aimed at non-IP
- # clients (like WAP devices), or behind proxies that set headers in an
- # incorrect or confusing way (like AWS ELB).
- #
- # The +custom_trusted+ argument can take a regex, which will be used
- # instead of +TRUSTED_PROXIES+, or a string, which will be used in addition
- # to +TRUSTED_PROXIES+. Any proxy setup will put the value you want in the
- # middle (or at the beginning) of the X-Forwarded-For list, with your proxy
- # servers after it. If your proxies aren't removed, pass them in via the
- # +custom_trusted+ parameter. That way, the middleware will ignore those
- # IP addresses, and return the one that you want.
- def initialize(app, check_ip_spoofing = true, custom_proxies = nil)
- @app = app
- @check_ip = check_ip_spoofing
- @proxies = case custom_proxies
- when Regexp
- custom_proxies
- when nil
- TRUSTED_PROXIES
- else
- Regexp.union(TRUSTED_PROXIES, custom_proxies)
- end
- end
- # Since the IP address may not be needed, we store the object here
- # without calculating the IP to keep from slowing down the majority of
- # requests. For those requests that do need to know the IP, the
- # GetIp#calculate_ip method will calculate the memoized client IP address.
- def call(env)
- env["action_dispatch.remote_ip"] = GetIp.new(env, self)
- @app.call(env)
- end
- # The GetIp class exists as a way to defer processing of the request data
- # into an actual IP address. If the ActionDispatch::Request#remote_ip method
- # is called, this class will calculate the value and then memoize it.
- class GetIp
- # This constant contains a regular expression that validates every known
- # form of IP v4 and v6 address, with or without abbreviations, adapted
- # from {this gist}[https://gist.github.com/gazay/1289635].
- VALID_IP = %r{
- (^(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[0-9]{1,2})(\.(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[0-9]{1,2})){3}$) | # ip v4
- (^(
- (([0-9A-Fa-f]{1,4}:){7}[0-9A-Fa-f]{1,4}) | # ip v6 not abbreviated
- (([0-9A-Fa-f]{1,4}:){6}:[0-9A-Fa-f]{1,4}) | # ip v6 with double colon in the end
- (([0-9A-Fa-f]{1,4}:){5}:([0-9A-Fa-f]{1,4}:)?[0-9A-Fa-f]{1,4}) | # - ip addresses v6
- (([0-9A-Fa-f]{1,4}:){4}:([0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4}) | # - with
- (([0-9A-Fa-f]{1,4}:){3}:([0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4}) | # - double colon
- (([0-9A-Fa-f]{1,4}:){2}:([0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4}) | # - in the middle
- (([0-9A-Fa-f]{1,4}:){6} ((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3} (\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
- (([0-9A-Fa-f]{1,4}:){1,5}:((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
- (([0-9A-Fa-f]{1,4}:){1}:([0-9A-Fa-f]{1,4}:){0,4}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
- (([0-9A-Fa-f]{1,4}:){0,2}:([0-9A-Fa-f]{1,4}:){0,3}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
- (([0-9A-Fa-f]{1,4}:){0,3}:([0-9A-Fa-f]{1,4}:){0,2}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
- (([0-9A-Fa-f]{1,4}:){0,4}:([0-9A-Fa-f]{1,4}:){1}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
- (::([0-9A-Fa-f]{1,4}:){0,5}((\b((25[0-5])|(1\d{2})|(2[0-4]\d) |(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
- ([0-9A-Fa-f]{1,4}::([0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4}) | # ip v6 with compatible to v4
- (::([0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4}) | # ip v6 with double colon at the beginning
- (([0-9A-Fa-f]{1,4}:){1,7}:) # ip v6 without ending
- )$)
- }x
- def initialize(env, middleware)
- @env = env
- @check_ip = middleware.check_ip
- @proxies = middleware.proxies
- end
- # Sort through the various IP address headers, looking for the IP most
- # likely to be the address of the actual remote client making this
- # request.
- #
- # REMOTE_ADDR will be correct if the request is made directly against the
- # Ruby process, on e.g. Heroku. When the request is proxied by another
- # server like HAProxy or Nginx, the IP address that made the original
- # request will be put in an X-Forwarded-For header. If there are multiple
- # proxies, that header may contain a list of IPs. Other proxy services
- # set the Client-Ip header instead, so we check that too.
- #
- # As discussed in {this post about Rails IP Spoofing}[http://blog.gingerlime.com/2012/rails-ip-spoofing-vulnerabilities-and-protection/],
- # while the first IP in the list is likely to be the "originating" IP,
- # it could also have been set by the client maliciously.
- #
- # In order to find the first address that is (probably) accurate, we
- # take the list of IPs, remove known and trusted proxies, and then take
- # the last address left, which was presumably set by one of those proxies.
- def calculate_ip
- # Set by the Rack web server, this is a single value.
- remote_addr = ips_from('REMOTE_ADDR').last
- # Could be a CSV list and/or repeated headers that were concatenated.
- client_ips = ips_from('HTTP_CLIENT_IP').reverse
- forwarded_ips = ips_from('HTTP_X_FORWARDED_FOR').reverse
- # +Client-Ip+ and +X-Forwarded-For+ should not, generally, both be set.
- # If they are both set, it means that this request passed through two
- # proxies with incompatible IP header conventions, and there is no way
- # for us to determine which header is the right one after the fact.
- # Since we have no idea, we give up and explode.
- should_check_ip = @check_ip && client_ips.last && forwarded_ips.last
- if should_check_ip && !forwarded_ips.include?(client_ips.last)
- # We don't know which came from the proxy, and which from the user
- raise IpSpoofAttackError, "IP spoofing attack?! " +
- "HTTP_CLIENT_IP=#{@env['HTTP_CLIENT_IP'].inspect} " +
- "HTTP_X_FORWARDED_FOR=#{@env['HTTP_X_FORWARDED_FOR'].inspect}"
- end
- # We assume these things about the IP headers:
- #
- # - X-Forwarded-For will be a list of IPs, one per proxy, or blank
- # - Client-Ip is propagated from the outermost proxy, or is blank
- # - REMOTE_ADDR will be the IP that made the request to Rack
- ips = [forwarded_ips, client_ips, remote_addr].flatten.compact
- # If every single IP option is in the trusted list, just return REMOTE_ADDR
- filter_proxies(ips).first || remote_addr
- end
- # Memoizes the value returned by #calculate_ip and returns it for
- # ActionDispatch::Request to use.
- def to_s
- @ip ||= calculate_ip
- end
- protected
- def ips_from(header)
- # Split the comma-separated list into an array of strings
- ips = @env[header] ? @env[header].strip.split(/[,\s]+/) : []
- # Only return IPs that are valid according to the regex
- ips.select{ |ip| ip =~ VALID_IP }
- end
- def filter_proxies(ips)
- ips.reject { |ip| ip =~ @proxies }
- end
- end
- end
- end