Class: Audioproxy::UrlBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/audioproxy/url_builder.rb

Overview

Assembles {endpoint}/{signature}/{options}/{source} URLs, byte-compatible with the proxy's reference signer.

The signature covers everything after itself (leading / included), so an endpoint path prefix cannot disturb it.

This is the Rails-facing half and may use ActiveSupport freely. The HMAC itself lives in Audioproxy::Signer, which may not — see D1.

Constant Summary collapse

INSECURE_SEGMENT =

Literal signature segment the proxy accepts under AP_ALLOW_INSECURE.

"insecure".freeze
FALLBACK_OPTIONS =

The proxy's path grammar has no optionless form, so the minimal always-valid options string is its default format spelled out.

"f:mp3".freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config = Audioproxy.config) ⇒ UrlBuilder

Returns a new instance of UrlBuilder.



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# File 'lib/audioproxy/url_builder.rb', line 24

def initialize(config = Audioproxy.config)
  @config = config
end

Instance Attribute Details

#config ⇒ Object (readonly)

Returns the value of attribute config.



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# File 'lib/audioproxy/url_builder.rb', line 22

def config
  @config
end

Instance Method Details

#sign(rest_of_path) ⇒ Object

Signs via Audioproxy::Signer. Whether the config can sign is this class's problem; how the bytes are produced is the signer's.



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# File 'lib/audioproxy/url_builder.rb', line 57

def sign(rest_of_path)
  missing = [ (:key unless config.key), (:salt unless config.salt) ].compact
  unless missing.empty?
    raise ConfigurationError, "Audioproxy cannot sign a URL: #{missing.join(" and ")} not configured (set them, or use unsigned: true)"
  end

  Signer.new(key: config.key, salt: config.salt).sign(rest_of_path)
end

#url_for(source, raw: nil, endpoint: nil, unsigned: nil, expires_in: Expiry::UNSET, expires_at: Expiry::UNSET, **typed) ⇒ Object

Typed option keys (+f:+, br:, t: …) arrive as keyword arguments and render in the order they were written. Each is also accepted as its spelled-out alias (+format:+, bitrate:, trim: …), resolved to the canonical key before anything is rendered. A keyword that is neither a builder option nor a proxy option key raises rather than being ignored.

expires_in: (a duration or Integer seconds from now) and expires_at: (the instant itself) are mutually exclusive and time-box this one URL, overriding config.expires_in; either given as nil opts out of it (D6).

Raises:



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# File 'lib/audioproxy/url_builder.rb', line 37

def url_for(source, raw: nil, endpoint: nil, unsigned: nil,
            expires_in: Expiry::UNSET, expires_at: Expiry::UNSET, **typed)
  base = endpoint.nil? ? config.endpoint : Config.new.tap { |c| c.endpoint = endpoint }.endpoint
  raise ConfigurationError, "Audioproxy has no endpoint configured" if base.nil?

  # Once per URL, so the window arithmetic and the past-check cannot
  # straddle a second boundary (D4).
  expiry = Expiry.timestamp(
    expires_in: expires_in, expires_at: expires_at,
    default_expires_in: config.expires_in, now: Time.now.to_i
  )

  rest_of_path = "/#{options_segment(raw, typed, expiry)}/#{source_segment(source)}"
  insecure = unsigned.nil? ? config.unsigned : unsigned

  "#{base}/#{insecure ? INSECURE_SEGMENT : sign(rest_of_path)}#{rest_of_path}"
end