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# frozen_string_literal: true
module ActionDispatch
# This middleware is added to the stack when `config.force_ssl = true`, and is passed
# the options set in `config.ssl_options`. It does three jobs to enforce secure HTTP
# requests:
#
# 1. TLS redirect: Permanently redirects http:// requests to https://
# with the same URL host, path, etc. Enabled by default. Set `config.ssl_options`
# to modify the destination URL
# (e.g. `redirect: { host: "secure.widgets.com", port: 8080 }`), or set
# `redirect: false` to disable this feature.
#
# 2. Secure cookies: Sets the `secure` flag on cookies to tell browsers they
# mustn't be sent along with http:// requests. Enabled by default. Set
# `config.ssl_options` with `secure_cookies: false` to disable this feature.
#
# 3. HTTP Strict Transport Security (HSTS): Tells the browser to remember
# this site as TLS-only and automatically redirect non-TLS requests.
# Enabled by default. Configure `config.ssl_options` with `hsts: false` to disable.
#
# Set `config.ssl_options` with `hsts: { … }` to configure HSTS:
# * `expires`: How long, in seconds, these settings will stick. The minimum
# required to qualify for browser preload lists is `18.weeks`. Defaults to
# `180.days` (recommended).
# * `subdomains`: Set to `true` to tell the browser to apply these settings
# to all subdomains. This protects your cookies from interception by a
# vulnerable site on a subdomain. Defaults to `true`.
# * `preload`: Advertise that this site may be included in browsers'
# preloaded HSTS lists. HSTS protects your site on every visit *except the
# first visit* since it hasn't seen your HSTS header yet. To close this
# gap, browser vendors include a baked-in list of HSTS-enabled sites.
# Go to https://hstspreload.appspot.com to submit your site for inclusion.
# Defaults to `false`.
#
# To turn off HSTS, omitting the header is not enough. Browsers will remember the
# original HSTS directive until it expires. Instead, use the header to tell browsers to
# expire HSTS immediately. Setting `hsts: false` is a shortcut for
# `hsts: { expires: 0 }`.
#
# Requests can opt-out of redirection with `exclude`:
#
# config.ssl_options = { redirect: { exclude: -> request { request.path =~ /healthcheck/ } } }
class SSL
# Default to 180 days, the low end for https://www.ssllabs.com/ssltest/
# and greater than the 18-week requirement for browser preload lists.
HSTS_EXPIRES_IN = 15552000
def self.default_hsts_options
{ expires: HSTS_EXPIRES_IN, subdomains: true, preload: false }
end
def initialize(app, redirect: {}, hsts: {}, secure_cookies: true)
@app = app
@redirect = redirect
@exclude = @redirect && @redirect[:exclude] || proc { !@redirect }
@secure_cookies = secure_cookies
@hsts_header = build_hsts_header(normalize_hsts_options(hsts))
end
def call(env)
request = Request.new env
if request.ssl?
@app.call(env).tap do |status, headers, body|
set_hsts_header! headers
flag_cookies_as_secure! headers if @secure_cookies
end
else
return redirect_to_https request unless @exclude.call(request)
@app.call(env)
end
end
private
def set_hsts_header!(headers)
headers["Strict-Transport-Security".freeze] ||= @hsts_header
end
def normalize_hsts_options(options)
case options
# Explicitly disabling HSTS clears the existing setting from browsers
# by setting expiry to 0.
when false
self.class.default_hsts_options.merge(expires: 0)
# Default to enabled, with default options.
when nil, true
self.class.default_hsts_options
else
self.class.default_hsts_options.merge(options)
end
end
# https://tools.ietf.org/html/rfc6797#section-6.1
def build_hsts_header(hsts)
value = "max-age=#{hsts[:expires].to_i}".dup
value << "; includeSubDomains" if hsts[:subdomains]
value << "; preload" if hsts[:preload]
value
end
def flag_cookies_as_secure!(headers)
if cookies = headers["Set-Cookie".freeze]
cookies = cookies.split("\n".freeze)
headers["Set-Cookie".freeze] = cookies.map { |cookie|
if cookie !~ /;\s*secure\s*(;|$)/i
"#{cookie}; secure"
else
cookie
end
}.join("\n".freeze)
end
end
def redirect_to_https(request)
[ @redirect.fetch(:status, redirection_status(request)),
{ "Content-Type" => "text/html",
"Location" => https_location_for(request) },
@redirect.fetch(:body, []) ]
end
def redirection_status(request)
if request.get? || request.head?
301 # Issue a permanent redirect via a GET request.
else
307 # Issue a fresh request redirect to preserve the HTTP method.
end
end
def https_location_for(request)
host = @redirect[:host] || request.host
port = @redirect[:port] || request.port
location = "https://#{host}".dup
location << ":#{port}" if port != 80 && port != 443
location << request.fullpath
location
end
end
end
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