Mail::SPF::Server(3)                           User Contributed Perl Documentation                          Mail::SPF::Server(3)



NAME
       Mail::SPF::Server - Server class for processing SPF requests

SYNOPSIS
           use Mail::SPF;

           my $spf_server  = Mail::SPF::Server->new(
               # Optional custom default for authority explanation:
               default_authority_explanation =>
                   'See http://www.%{d}/why/id=%{S};ip=%{I};r=%{R}'
           );

           my $result      = $spf_server->process($request);

DESCRIPTION
       Mail::SPF::Server is a server class for processing SPF requests.  Each server instance can be configured with specific
       processing parameters.  Also, the default Net::DNS::Resolver DNS resolver used for making DNS look-ups can be overridden
       with a custom resolver object.

   Constructor
       The following constructor is provided:

       new(%options): returns Mail::SPF::Server
           Creates a new server object for processing SPF requests.

           %options is a list of key/value pairs representing any of the following options:

           default_authority_explanation
               A string denoting the default (not macro-expanded) authority explanation string to use if the authority domain
               does not specify an explanation string of its own.  Defaults to:

                   'Please see http://www.openspf.org/Why?s=%{_scope};id=%{S};ip=%{C};r=%{R}'

               As can be seen from the default, a non-standard "_scope" pseudo macro is supported that expands to the name of
               the identity's scope.  (Note: Do not use any non-standard macros in explanation strings published in DNS.)

           hostname
               A string denoting the local system's fully qualified host name that should be used for expanding the "r" macro in
               explanation strings.  Defaults to the system's configured host name.

           dns_resolver
               An optional DNS resolver object.  If none is specified, a new Net::DNS::Resolver object is used.  The resolver
               object may be of a different class, but it must provide an interface similar to Net::DNS::Resolver -- at least
               the "send" and "errorstring" methods must be supported, and the "send" method must return either an object of
               class Net::DNS::Packet, or, in the case of an error, undef.

           query_rr_types
               For which RR types to query when looking up and selecting SPF records.  The following values are supported:

               Mail::SPF::Server->query_rr_type_all (default)
                   Both "SPF" and "TXT" type RRs.

               Mail::SPF::Server->query_rr_type_spf
                   "SPF" type RRs only.

               Mail::SPF::Server->query_rr_type_txt
                   "TXT" type RRs only.

               Some (few) name servers suffer from serious brain damage with regard to the handling of queries for RR types that
               are unknown to them, such as the "SPF" RR type, so some (few) Mail::SPF users have expressed the desire for a way
               to disable the retrieval of "SPF" type RRs.  It is, however, a better idea to pressure the manufacturers of such
               broken name servers into fixing their products.

               See RFC 4408, 3.1.1, for a discussion of the topic, as well as the description of the "select_record" method.

           max_dns_interactive_terms
               An integer denoting the maximum number of terms (mechanisms and modifiers) per SPF check that perform DNS look-
               ups, as defined in RFC 4408, 10.1, paragraph 6.  If undef is specified, there is no limit on the number of such
               terms.  Defaults to 10, which is the value defined in RFC 4408.

               A value above the default is strongly discouraged for security reasons.  A value below the default has
               implications with regard to the predictability of SPF results.  Only deviate from the default if you know what
               you are doing!

           max_name_lookups_per_term
               An integer denoting the maximum number of DNS name look-ups per term (mechanism or modifier), as defined in RFC
               4408, 10.1, paragraph 7.  If undef is specified, there is no limit on the number of look-ups performed.  Defaults
               to 10, which is the value defined in RFC 4408.

               A value above the default is strongly discouraged for security reasons.  A value below the default has
               implications with regard to the predictability of SPF results.  Only deviate from the default if you know what
               you are doing!

           max_name_lookups_per_mx_mech
           max_name_lookups_per_ptr_mech
               An integer denoting the maximum number of DNS name look-ups per mx or ptr mechanism, respectively.  Defaults to
               the value of the "max_name_lookups_per_term" option.  See there for additional information and security notes.

           max_void_dns_lookups
               An integer denoting the maximum number of "void" DNS look-ups per SPF check, i.e. the number of DNS look-ups that
               were caused by DNS-interactive terms and macros (as defined in RFC 4408, 10.1, paragraphs 6 and 7) and that are
               allowed to return an empty answer with RCODE 0 or RCODE 3 ("NXDOMAIN") before processing is aborted with a
               "permerror" result.  If undef is specified, there is no stricter limit on the number of void DNS look-ups beyond
               the usual processing limits.  Defaults to 2.

               Specifically, the DNS look-ups that are subject to this limit are those caused by the "a", "mx", "ptr", and
               "exists" mechanisms and the "p" macro.

               A value of 2 is likely to prevent effective DoS attacks against third-party victim domains.  However, a definite
               limit may cause "permerror" results even with certain (overly complex) innocent sender policies where useful
               results would normally be returned.

   Class methods
       The following class methods are provided:

       result_class: returns class
       result_class($name): returns class
           Returns a Mail::SPF::Result descendent class determined from the given result name via the server's inherent result
           base class, or returns the server's inherent result base class if no result name is given.  This method may also be
           used as an instance method.

           Note:  Do not write code invoking class methods on literal result class names as this would ignore any derivative
           result classes provided by Mail::SPF extension modules.

       throw_result($name, $request): throws Mail::SPF::Result
       throw_result($name, $request, $text): throws Mail::SPF::Result
           Throws a Mail::SPF::Result descendant determined from the given result name via the server's inherent result base
           class, passing an optional result text and associating the given Mail::SPF::Request object with the result object.
           This method may also be used as an instance method.

           Note:  Do not write code invoking "throw" on literal result class names as this would ignore any derivative result
           classes provided by Mail::SPF extension modules.

   Instance methods
       The following instance methods are provided:

       process($request): returns Mail::SPF::Result
           Processes the given Mail::SPF::Request object, queries the authoritative domain for an SPF sender policy (see the
           description of the "select_record" method), evaluates the policy with regard to the given identity and other request
           parameters, and returns a Mail::SPF::Result object denoting the result of the policy evaluation.  See RFC 4408, 4,
           and RFC 4406, 4, for details.

       select_record($request): returns Mail::SPF::Record; throws Mail::SPF::EDNSError, Mail::SPF::ENoAcceptableRecord,
       Mail::SPF::ERedundantAcceptableRecords, Mail::SPF::ESyntaxError
           Queries the authority domain of the given Mail::SPF::Request object for SPF sender policy records and, if multiple
           records are available, selects the record of the highest acceptable record version that covers the requested scope.

           More precisely, the following algorithm is performed:

           1.  Determine the authority domain, the set of acceptable SPF record versions, and the identity scope from the given
               request object.

           2.  Query the authority domain for SPF records of the "SPF" DNS RR type, discarding any records that are of an
               inacceptable version or do not cover the desired scope.

               If this yields no SPF records, query the authority domain for SPF records of the "TXT" DNS RR type, discarding
               any records that are of an inacceptable version or do not cover the desired scope.

               If still no acceptable SPF records could be found, throw a Mail::SPF::ENoAcceptableRecord exception.

           3.  Discard all records but those of the highest acceptable version found.

               If exactly one record remains, return it.  Otherwise, throw a Mail::SPF::ERedundantAcceptableRecords exception.

           If the querying of either RR type has been disabled via the "new" constructor's "query_rr_types" option, the
           respective part in step 2 will be skipped.

           Mail::SPF::EDNSError exceptions due to DNS look-ups and Mail::SPF::ESyntaxError exceptions due to invalid acceptable
           records may also be thrown.

       get_acceptable_records_from_packet($packet, $rr_type, \@versions, $scope, $domain): returns list of Mail::SPF::Record
           Filters from the given Net::DNS::Packet object all resource records of the given RR type and for the given domain
           name, discarding any records that are not SPF records at all, that are of an inacceptable SPF record version, or that
           do not cover the given scope.  Returns a list of acceptable records.

       dns_lookup($domain, $rr_type): returns Net::DNS::Packet; throws Mail::SPF::EDNSTimeout, Mail::SPF::EDNSError
           Queries the DNS using the configured resolver for resource records of the desired type at the specified domain and
           returns a Net::DNS::Packet object if an answer packet was received.  Throws a Mail::SPF::EDNSTimeout exception if a
           DNS time-out occurred.  Throws a Mail::SPF::EDNSError exception if an error (other than RCODE 3 AKA "NXDOMAIN")
           occurred.

       count_dns_interactive_term($request): throws Mail::SPF::EProcessingLimitExceeded
           Increments by one the count of DNS-interactive mechanisms and modifiers that have been processed so far during the
           evaluation of the given Mail::SPF::Request object.  If this exceeds the configured limit (see the "new" constructor's
           "max_dns_interactive_terms" option), throws a Mail::SPF::EProcessingLimitExceeded exception.

           This method is supposed to be called by the "match" and "process" methods of Mail::SPF::Mech and Mail::SPF::Mod sub-
           classes before (and only if) they do any DNS look-ups.

       count_void_dns_lookup($request): throws Mail::SPF::EProcessingLimitExceeded
           Increments by one the count of "void" DNS look-ups that have occurred so far during the evaluation of the given
           Mail::SPF::Request object.  If this exceeds the configured limit (see the "new" constructor's "max_void_dns_lookups"
           option), throws a Mail::SPF::EProcessingLimitExceeded exception.

           This method is supposed to be called by any code after any calls to the "dns_lookup" method whenever (i) no answer
           records were returned, and (ii) this fact is a possible indication of a DoS attack against a third-party victim
           domain, and (iii) the number of "void" look-ups is not already constrained otherwise (as for example is the case with
           the "include" mechanism and the "redirect" modifier).  Specifically, this applies to look-ups performed by the "a",
           "mx", "ptr", and "exists" mechanisms and the "p" macro.

       default_authority_explanation: returns Mail::SPF::MacroString
           Returns the default authority explanation as a MacroString object.  See the description of the "new" constructor's
           "default_authority_explanation" option.

       hostname: returns string
           Returns the local system's host name.  See the description of the "new" constructor's "hostname" option.

       dns_resolver: returns Net::DNS::Resolver or compatible object
           Returns the DNS resolver object of the server object.  See the description of the "new" constructor's "dns_resolver"
           option.

       query_rr_types: returns integer
           Returns a value denoting the RR types for which to query when looking up and selecting SPF records.  See the
           description of the "new" constructor's "query_rr_types" option.

       max_dns_interactive_terms: returns integer
       max_name_lookups_per_term: returns integer
       max_name_lookups_per_mx_mech: returns integer
       max_name_lookups_per_ptr_mech: returns integer
       max_void_dns_lookups: returns integer
           Return the limit values of the server object.  See the description of the "new" constructor's corresponding options.

SEE ALSO
       Mail::SPF, Mail::SPF::Request, Mail::SPF::Result

       <http://www.ietf.org/rfc/rfc4408.txt>;

       For availability, support, and license information, see the README file included with Mail::SPF.

AUTHORS
       Julian Mehnle <julianATmehnle.net>, Shevek <cpanATanarres.org>



perl v5.12.2                                               2010-12-06                                       Mail::SPF::Server(3)