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require 'rack/file'
module Rack
# = Sendfile
#
# The Sendfile middleware intercepts responses whose body is being
# served from a file and replaces it with a server specific X-Sendfile
# header. The web server is then responsible for writing the file contents
# to the client. This can dramatically reduce the amount of work required
# by the Ruby backend and takes advantage of the web server's optimized file
# delivery code.
#
# In order to take advantage of this middleware, the response body must
# respond to +to_path+ and the request must include an X-Sendfile-Type
# header. Rack::File and other components implement +to_path+ so there's
# rarely anything you need to do in your application. The X-Sendfile-Type
# header is typically set in your web servers configuration. The following
# sections attempt to document
#
# === Nginx
#
# Nginx supports the X-Accel-Redirect header. This is similar to X-Sendfile
# but requires parts of the filesystem to be mapped into a private URL
# hierarachy.
#
# The following example shows the Nginx configuration required to create
# a private "/files/" area, enable X-Accel-Redirect, and pass the special
# X-Sendfile-Type and X-Accel-Mapping headers to the backend:
#
# location ~ /files/(.*) {
# internal;
# alias /var/www/$1;
# }
#
# location / {
# proxy_redirect off;
#
# proxy_set_header Host $host;
# proxy_set_header X-Real-IP $remote_addr;
# proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
#
# proxy_set_header X-Sendfile-Type X-Accel-Redirect;
# proxy_set_header X-Accel-Mapping /var/www/=/files/;
#
# proxy_pass http://127.0.0.1:8080/;
# }
#
# Note that the X-Sendfile-Type header must be set exactly as shown above.
# The X-Accel-Mapping header should specify the location on the file system,
# followed by an equals sign (=), followed name of the private URL pattern
# that it maps to. The middleware performs a simple substitution on the
# resulting path.
#
# See Also: http://wiki.codemongers.com/NginxXSendfile
#
# === lighttpd
#
# Lighttpd has supported some variation of the X-Sendfile header for some
# time, although only recent version support X-Sendfile in a reverse proxy
# configuration.
#
# $HTTP["host"] == "example.com" {
# proxy-core.protocol = "http"
# proxy-core.balancer = "round-robin"
# proxy-core.backends = (
# "127.0.0.1:8000",
# "127.0.0.1:8001",
# ...
# )
#
# proxy-core.allow-x-sendfile = "enable"
# proxy-core.rewrite-request = (
# "X-Sendfile-Type" => (".*" => "X-Sendfile")
# )
# }
#
# See Also: http://redmine.lighttpd.net/wiki/lighttpd/Docs:ModProxyCore
#
# === Apache
#
# X-Sendfile is supported under Apache 2.x using a separate module:
#
# https://tn123.org/mod_xsendfile/
#
# Once the module is compiled and installed, you can enable it using
# XSendFile config directive:
#
# RequestHeader Set X-Sendfile-Type X-Sendfile
# ProxyPassReverse / http://localhost:8001/
# XSendFile on
#
# === Mapping parameter
#
# The third parameter allows for an overriding extension of the
# X-Accel-Mapping header. Mappings should be provided in tuples of internal to
# external. The internal values may contain regular expression syntax, they
# will be matched with case indifference.
class Sendfile
F = ::File
def initialize(app, variation=nil, mappings=[])
@app = app
@variation = variation
@mappings = mappings.map do |internal, external|
[/^#{internal}/i, external]
end
end
def call(env)
status, headers, body = @app.call(env)
if body.respond_to?(:to_path)
case type = variation(env)
when 'X-Accel-Redirect'
path = F.expand_path(body.to_path)
if url = map_accel_path(env, path)
headers['Content-Length'] = '0'
headers[type] = url
body.close if body.respond_to?(:close)
body = []
else
env['rack.errors'].puts "X-Accel-Mapping header missing"
end
when 'X-Sendfile', 'X-Lighttpd-Send-File'
path = F.expand_path(body.to_path)
headers['Content-Length'] = '0'
headers[type] = path
body.close if body.respond_to?(:close)
body = []
when '', nil
else
env['rack.errors'].puts "Unknown x-sendfile variation: '#{variation}'.\n"
end
end
[status, headers, body]
end
private
def variation(env)
@variation ||
env['sendfile.type'] ||
env['HTTP_X_SENDFILE_TYPE']
end
def map_accel_path(env, path)
if mapping = @mappings.find { |internal,_| internal =~ path }
path.sub(*mapping)
elsif mapping = env['HTTP_X_ACCEL_MAPPING']
internal, external = mapping.split('=', 2).map{ |p| p.strip }
path.sub(/^#{internal}/i, external)
end
end
end
end
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