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module ActionDispatch
class RemoteIp
class IpSpoofAttackError < StandardError ; end
# IP addresses that are "trusted proxies" that can be stripped from
# the comma-delimited list in the X-Forwarded-For header. See also:
# http://en.wikipedia.org/wiki/Private_network#Private_IPv4_address_spaces
# http://en.wikipedia.org/wiki/Private_network#Private_IPv6_addresses.
TRUSTED_PROXIES = %r{
^127\.0\.0\.1$ | # localhost
^::1$ |
^(10 | # private IP 10.x.x.x
172\.(1[6-9]|2[0-9]|3[0-1]) | # private IP in the range 172.16.0.0 .. 172.31.255.255
192\.168 | # private IP 192.168.x.x
fc00:: # private IP fc00
)\.
}x
attr_reader :check_ip, :proxies
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
def call(env)
env["action_dispatch.remote_ip"] = GetIp.new(env, self)
@app.call(env)
end
class GetIp
# IP v4 and v6 (with compression) validation regexp
# https://gist.github.com/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}$) | # ip v4
(^(
(([0-9A-Fa-f]{1,4}:){7}[0-9A-Fa-f]{1,4}) | # ip v6 not abbreviated
(([0-9A-Fa-f]{1,4}:){6}:[0-9A-Fa-f]{1,4}) | # ip v6 with double colon in the end
(([0-9A-Fa-f]{1,4}:){5}:([0-9A-Fa-f]{1,4}:)?[0-9A-Fa-f]{1,4}) | # - ip addresses v6
(([0-9A-Fa-f]{1,4}:){4}:([0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa-f]{1,4}) | # - with
(([0-9A-Fa-f]{1,4}:){3}:([0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1,4}) | # - double colon
(([0-9A-Fa-f]{1,4}:){2}:([0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4}) | # - in the middle
(([0-9A-Fa-f]{1,4}:){6} ((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3} (\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
(([0-9A-Fa-f]{1,4}:){1,5}:((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
(([0-9A-Fa-f]{1,4}:){1}:([0-9A-Fa-f]{1,4}:){0,4}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
(([0-9A-Fa-f]{1,4}:){0,2}:([0-9A-Fa-f]{1,4}:){0,3}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
(([0-9A-Fa-f]{1,4}:){0,3}:([0-9A-Fa-f]{1,4}:){0,2}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
(([0-9A-Fa-f]{1,4}:){0,4}:([0-9A-Fa-f]{1,4}:){1}((\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
(::([0-9A-Fa-f]{1,4}:){0,5}((\b((25[0-5])|(1\d{2})|(2[0-4]\d) |(\d{1,2}))\b)\.){3}(\b((25[0-5])|(1\d{2})|(2[0-4]\d)|(\d{1,2}))\b)) | # ip v6 with compatible to v4
([0-9A-Fa-f]{1,4}::([0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4}) | # ip v6 with compatible to v4
(::([0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4}) | # ip v6 with double colon at the begining
(([0-9A-Fa-f]{1,4}:){1,7}:) # ip v6 without ending
)$)
}x
def initialize(env, middleware)
@env = env
@middleware = middleware
@ip = nil
end
# Determines originating IP address. REMOTE_ADDR is the standard
# but will be wrong if the user is behind a proxy. Proxies will set
# HTTP_CLIENT_IP and/or HTTP_X_FORWARDED_FOR, so we prioritize those.
# HTTP_X_FORWARDED_FOR may be a comma-delimited list in the case of
# multiple chained proxies. The first address which is in this list
# if it's not a known proxy will be the originating IP.
# Format of HTTP_X_FORWARDED_FOR:
# client_ip, proxy_ip1, proxy_ip2...
# http://en.wikipedia.org/wiki/X-Forwarded-For
def calculate_ip
client_ip = @env['HTTP_CLIENT_IP']
forwarded_ip = ips_from('HTTP_X_FORWARDED_FOR').first
remote_addrs = ips_from('REMOTE_ADDR')
check_ip = client_ip && @middleware.check_ip
if check_ip && forwarded_ip != client_ip
# 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
client_ips = remove_proxies [client_ip, forwarded_ip, remote_addrs].flatten
if client_ips.present?
client_ips.first
else
# If there is no client ip we can return first valid proxy ip from REMOTE_ADDR
remote_addrs.find { |ip| valid_ip? ip }
end
end
def to_s
@ip ||= calculate_ip
end
private
def ips_from(header)
@env[header] ? @env[header].strip.split(/[,\s]+/) : []
end
def valid_ip?(ip)
ip =~ VALID_IP
end
def not_a_proxy?(ip)
ip !~ @middleware.proxies
end
def remove_proxies(ips)
ips.select { |ip| valid_ip?(ip) && not_a_proxy?(ip) }
end
end
end
end
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