Class: Falcon::Middleware::Proxy

Inherits:
Protocol::HTTP::Middleware
  • Object
show all
Defined in:
lib/falcon/middleware/proxy.rb

Overview

A HTTP middleware for proxying requests to a given set of hosts. Typically used for implementing virtual servers.

Constant Summary collapse

FORWARDED = 
'forwarded'
X_FORWARDED_FOR = 
'x-forwarded-for'
X_FORWARDED_PROTO = 
'x-forwarded-proto'
VIA = 
'via'
CONNECTION = 
'connection'
HOP_HEADERS =

HTTP hop headers which should not be passed through the proxy.

[
	'connection',
	'keep-alive',
	'public',
	'proxy-authenticate',
	'transfer-encoding',
	'upgrade',
]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app, hosts) ⇒ Proxy

Initialize the proxy middleware.



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# File 'lib/falcon/middleware/proxy.rb', line 62

def initialize(app, hosts)
	super(app)
	
	@server_context = nil
	
	@hosts = hosts
	@clients = {}
	
	@count = 0
end

Instance Attribute Details

#count ⇒ Object (readonly)

The number of requests that have been proxied.



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# File 'lib/falcon/middleware/proxy.rb', line 75

def count
  @count
end

Instance Method Details

#call(request) ⇒ Object

Proxy the request if the authority matches a specific host.



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# File 'lib/falcon/middleware/proxy.rb', line 148

def call(request)
	if host = lookup(request)
		@count += 1
		
		request = self.prepare_request(request, host)
		
		client = connect(host.endpoint)
		
		client.call(request)
	else
		super
	end
rescue
	Console.logger.error(self) {$!}
	return Protocol::HTTP::Response[502, {'content-type' => 'text/plain'}, ["#{$!.inspect}: #{$!.backtrace.join("\n")}"]]
end

#close ⇒ Object

Close all the connections to the upstream hosts.



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# File 'lib/falcon/middleware/proxy.rb', line 78

def close
	@clients.each_value(&:close)
	
	super
end

#connect(endpoint) ⇒ Object

Establish a connection to the specified upstream endpoint.



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# File 'lib/falcon/middleware/proxy.rb', line 86

def connect(endpoint)
	@clients[endpoint] ||= Async::HTTP::Client.new(endpoint)
end

#lookup(request) ⇒ Object

Lookup the appropriate host for the given request.



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# File 'lib/falcon/middleware/proxy.rb', line 93

def lookup(request)
	# Trailing dot and port is ignored/normalized.
	if authority = request.authority&.sub(/(\.)?(:\d+)?$/, '')
		return @hosts[authority]
	end
end

#prepare_headers(headers) ⇒ Object

Prepare the headers to be sent to an upstream host. In particular, we delete all connection and hop headers.



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# File 'lib/falcon/middleware/proxy.rb', line 102

def prepare_headers(headers)
	if connection = headers[CONNECTION]
		headers.extract(connection)
	end
	
	headers.extract(HOP_HEADERS)
end

#prepare_request(request, host) ⇒ Object

Prepare the request to be proxied to the specified host. In particular, we set appropriate VIA, FORWARDED, X_FORWARDED_FOR and X_FORWARDED_PROTO headers.



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# File 'lib/falcon/middleware/proxy.rb', line 112

def prepare_request(request, host)
	forwarded = []
	
	Console.logger.debug(self) do |buffer|
		buffer.puts "Request authority: #{request.authority}"
		buffer.puts "Host authority: #{host.authority}"
		buffer.puts "Request: #{request.method} #{request.path} #{request.version}"
		buffer.puts "Request headers: #{request.headers.inspect}"
	end
	
	# The authority of the request must match the authority of the endpoint we are proxying to, otherwise SNI and other things won't work correctly.
	request.authority = host.authority
	
	if address = request.remote_address
		request.headers.add(X_FORWARDED_FOR, address.ip_address)
		forwarded << "for=#{address.ip_address}"
	end
	
	if scheme = request.scheme
		request.headers.add(X_FORWARDED_PROTO, scheme)
		forwarded << "proto=#{scheme}"
	end
	
	unless forwarded.empty?
		request.headers.add(FORWARDED, forwarded.join(';'))
	end
	
	request.headers.add(VIA, "#{request.version} #{self.class}")
	
	self.prepare_headers(request.headers)
	
	return request
end