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📚 Document AUTHENTICATE command, Authenticators [🚧WIP:DRY]
These two pieces of documentation are meant to complement a new SASL::Authenticator base class and each of the individual authenticators.
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‎lib/net/imap.rb

Lines changed: 72 additions & 31 deletions
Original file line numberDiff line numberDiff line change
@@ -577,43 +577,58 @@ def starttls(options = {}, verify = true)
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end
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end
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##
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# :call-seq:
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# authenticate(mechanism, ...) -> ok_resp
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# authenticate(mechanism) -> ok_resp
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# authenticate(mechanism, username, password) -> ok_resp
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# authenticate(mechanism, authcid, secret, authzid) -> ok_resp
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# authenticate(mechanism, *credentials) -> ok_resp
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# authenticate(mechanism, **properties_and_callbacks) -> ok_resp
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# authenticate(mechanism) {|name, auth_ctx| prop_value } -> ok_resp
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# authenticate(mech, *creds, **props) {|prop, auth| val } -> ok_resp
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#
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# Sends an {AUTHENTICATE command [IMAP4rev1
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# §6.2.2]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.2.2]) to
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# authenticate the client.
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#
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# The +auth_type+ parameter is a string that
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# represents the authentication mechanism to be used. Currently Net::IMAP
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# supports the following mechanisms:
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# +mechanism+ is the name of the \SASL authentication mechanism to be used.
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# All other arguments are forwarded to the authenticator for the requested
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# mechanism. The listed call signatures are suggestions. <em>The
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# documentation for each individual mechanism must be consulted for its
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# specific parameters.</em>
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#
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# PLAIN:: Login using cleartext user and password. Secure with TLS.
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# See PlainAuthenticator.
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# CRAM-MD5:: DEPRECATED: Use PLAIN (or DIGEST-MD5) with TLS.
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# DIGEST-MD5:: DEPRECATED by RFC6331. Must be secured using TLS.
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# See DigestMD5Authenticator.
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# LOGIN:: DEPRECATED: Use PLAIN.
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#
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# Most mechanisms require two args: authentication identity (e.g. username)
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# and credentials (e.g. a password). But each mechanism requires and allows
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# different arguments; please consult the documentation for the specific
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# mechanisms you are using. <em>Several obsolete mechanisms are available
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# for backwards compatibility. Using deprecated mechanisms will issue
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# warnings.</em>
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#
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# Servers do not support all mechanisms and clients must not attempt to use
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# a mechanism unless "AUTH=#{mechanism}" is listed as a #capability.
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# Clients must not attempt to authenticate or #login when +LOGINDISABLED+ is
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# listed with the capabilities. Server capabilities, especially auth
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# mechanisms, do change after calling #starttls so they need to be checked
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# again.
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# <em>In general</em>, all of a mechanism's properties can be set by keyword
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# argument or callback, but mechanisms may allow common properties to be set
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# with positional arguments. See SASL::Authenticator@Properties and
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# SASL::Authenticator@Callbacks for more details.
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#
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# For example:
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# An exception Net::IMAP::NoResponseError is raised if authentication fails.
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#
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# imap.authenticate('PLAIN', user, password)
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# ==== Supported SASL Mechanisms
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#
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# A Net::IMAP::NoResponseError is raised if authentication fails.
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# Net::IMAP currently supports the following mechanisms:
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#
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# PLAIN:: Login using clear-text user and password. Secure with TLS.
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# See SASL::PlainAuthenticator.
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# XOAUTH2:: Login using a username and OAuth2 access token. Non-standard
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# and obsoleted by +OAUTHBEARER+, but still widely supported.
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# See SASL::XOAuth2Authenticator.
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#
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# See Net::IMAP::Authenticators for more information on plugging in your
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# own authenticator.
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# See Net::IMAP::Authenticators for information on plugging in
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# authenticators for other mechanisms. See the {SASL mechanism
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# registry}[https://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml]
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# for information on these and other SASL mechanisms.
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#
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# ===== Deprecated mechanisms
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#
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# <em>Obsolete mechanisms are available for backwards compatibility.
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# Using a deprecated mechanism will print a warning.</em>
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#
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# DIGEST-MD5:: DEPRECATED by RFC6331. Must be secured using TLS.
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# See SASL::DigestMD5Authenticator.
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# CRAM-MD5:: DEPRECATED: Use +PLAIN+ (or SCRAM-*)
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# LOGIN:: DEPRECATED: Use +PLAIN+ with TLS.
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#
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# ==== Capabilities
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#
@@ -626,9 +641,35 @@ def starttls(options = {}, verify = true)
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# Server capabilities may change after #starttls, #login, and #authenticate.
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# Any cached capabilities must be invalidated when this method completes.
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#
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def authenticate(auth_type, *args)
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authenticator = self.class.authenticator(auth_type, *args)
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send_command("AUTHENTICATE", auth_type) do |resp|
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# ==== Example
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# Because unhandled keyword arguments are ignored, the same config can be
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# used for multiple authenticator types.
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# password = nil # saved locally, so we don't ask more than once
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# creds = {
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# authcid: username,
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# password: proc { password ||= ui.prompt_for_password },
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# oauth2_token: proc { kms.lookup(username, :access_token) },
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# }
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# capa = imap.capability
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# if capa.include? "LOGINDISABLED"
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# raise "the server has disabled login"
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# elsif oauth2_token and capa.include? "AUTH=OAUTHBEARER"
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# imap.authenticate "OAUTHBEARER", **creds # authcid, oauth2_token
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# elsif oauth2_token and capa.include? "AUTH=XOAUTH2"
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# imap.authenticate "XOAUTH2", **creds # authcid, oauth2_token
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# elsif password and capa.include? "AUTH=SCRAM-SHA-256"
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# imap.authenticate "SCRAM-SHA-256", **creds # authcid, password
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# elsif password and capa.include? "AUTH=PLAIN"
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# imap.authenticate "PLAIN", **creds # authcid, password
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# elsif password and capa.include? "AUTH=DIGEST-MD5"
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# imap.authenticate "DIGEST-MD5", **creds # authcid, password
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# else
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# raise "no acceptable authentication mechanism is available"
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# end
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#
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def authenticate(mechanism, *args, **props, &cb)
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authenticator = self.class.authenticator(mechanism, *args, **props, &cb)
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send_command("AUTHENTICATE", mechanism) do |resp|
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if resp.instance_of?(ContinuationRequest)
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data = authenticator.process(resp.data.text.unpack("m")[0])
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s = [data].pack("m0")

‎lib/net/imap/authenticators.rb

Lines changed: 64 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -3,22 +3,75 @@
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# Registry for SASL authenticators used by Net::IMAP.
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module Net::IMAP::Authenticators
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# Adds an authenticator for use with Net::IMAP#authenticate. +auth_type+ is the
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# Adds an authenticator for Net::IMAP#authenticate to use. +mechanism+ is the
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# {SASL mechanism}[https://www.iana.org/assignments/sasl-mechanisms/sasl-mechanisms.xhtml]
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# supported by +authenticator+ (for instance, "+PLAIN+"). The +authenticator+
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# is an object which defines a +#process+ method to handle authentication with
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# the server. See Net::IMAP::PlainAuthenticator, Net::IMAP::LoginAuthenticator,
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# Net::IMAP::CramMD5Authenticator, and Net::IMAP::DigestMD5Authenticator for
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# examples.
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#
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# If +auth_type+ refers to an existing authenticator, it will be
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# replaced by the new one.
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# implemented by +authenticator+ (for instance, <tt>"PLAIN"</tt>).
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#
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# If +mechanism+ refers to an existing authenticator, a warning will be
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# printed and the old authenticator will be replaced.
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#
13+
# The +authenticator+ must respond to +#new+ (or #call), receiving the
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# authenticator configuration and return a configured authentication session.
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# The authenticator session must respond to +#process+, receiving the server's
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# challenge and returning the client's response. See PlainAuthenticator,
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# XOauth2Authenticator, DigestMD5Authenticator, etc for examples.
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def add_authenticator(auth_type, authenticator)
1719
authenticators[auth_type] = authenticator
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end
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20-
# Builds an authenticator for Net::IMAP#authenticate. +args+ will be passed
21-
# directly to the chosen authenticator's +#initialize+.
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# :call-seq:
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# authenticator(mechanism, ...) -> authenticator
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# authenticator(mechanism) -> authenticator
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# authenticator(mechanism, username, password) -> authenticator
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# authenticator(mechanism, authcid, secret, authzid) -> authenticator
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# authenticator(mechanism, *credentials) -> authenticator
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# authenticator(mechanism, **properties_and_callbacks) -> authenticator
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# authenticator(mechanism) {|name, auth_ctx| prop_value } -> authenticator
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# authenticator(mech, *creds, **props) {|prop, auth| val } -> authenticator
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#
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# Builds a new authentication session context for +mechanism+.
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#
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# [Note]
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# This method is intended for internal use by connection protocol code only.
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# Protocol client users should see refer to their client's documentation,
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# e.g. Net::IMAP#authenticate for Net::IMAP.
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#
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# The returned object represents a single authentication exchange and <em>must
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# not</em> be reused for multiple authentication attempts.
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#
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# The documented call signatures for this method are recommendations for
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# authenticator implementors. All arguments (other than +mechanism+) are
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# forwarded to the registered authenticator's +#new+ (or +#call+) method, and
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# each authenticator must document its own arguments.
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#
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# In general, mechanisms may be configured by positional arguments (convenient
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# for common scenarios), keyword arguments (handles any static property), a
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# callback, or a combination of the three. For example:
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#
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# # using positional parameters -- convenient for common scenarios
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# sasl_exchange = authenticator("PLAIN", "username", "password")
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# sasl_exchange.process(nil) # => "\0username\0password"
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#
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# # using keyword parameters -- can handle any static property
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# sasl_exchange = authenticator(
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# "PLAIN", authcid: "cid", password: "pass", authzid: "zid"
58+
# )
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# sasl_exchange.process(nil) # => "zid\0cid\0pass"
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#
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# # using a callback -- can be used for dynamic value lookup
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# sasl_exchange = authenticator("PLAIN") do |prop, _|
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# case prop
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# when :authcid then prompt_for("Username? ")
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# when :password then password_prompt
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# when :authzid then prompt_for("User to act on behalf of? ")
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# end
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# end
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#
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# # can combine all three: callback > keyword > positional
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# sasl_exchange = authenticator("PLAIN", "foo", authzid: "bar") do |prop, _|
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# prop == :password and password_prompt
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# end
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#
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def authenticator(mechanism, *authargs, **properties, &callback)
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authenticator = authenticators.fetch(mechanism.upcase) do
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raise ArgumentError, 'unknown auth type - "%s"' % mechanism

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