NAME
Net::DNS::SPF::Expander
DESCRIPTION
This module expands DNS SPF records, so you don't have to. The problem is that you only get 10 per SPF record, and recursions count against you. Your record won't validate.
Let's say you start with this as an SPF record:
@ TXT "v=spf1 include:_spf.google.com include:sendgrid.net a:hq1.campusexplorer.com a:hq2.campusexplorer.com a:mail2.campusexplorer.com ~all"You go to http://www.kitterman.com/spf/validate.html and check this record. It passes validation. But later you come back and add salesforce, so that you now have:
@ TXT "v=spf1 include:_spf.google.com include:sendgrid.net include:salesforce.com a:hq1.campusexplorer.com a:hq2.campusexplorer.com a:mail2.campusexplorer.com ~all"And now your record fails validation.
_spf.google.com takes 3 lookups.
_spf1.google.com
_spf2.google.com
_spf3.google.com
sendgrid.net takes 1 lookup.
_sendgrid.biz
hq1 takes 1 lookup.
hq2 takes 1 lookup.
mail2 takes 1 lookup.Salesforce adds:
_spf.google.com (3 you already did)
_spf1.google.com
_spf2.google.com
_spf3.google.com
mx takes 4 lookups.
salesforce.com.s8a1.psmtp.com.
salesforce.com.s8a2.psmtp.com.
salesforce.com.s8b1.psmtp.com.
salesforce.com.s8b2.psmtp.com.So now instead of 7 you have 14. The common advice is to expand them, and that is a tedious process. It's especially tedious when, say, salesforce changes their mx record.
So this module and the accompanying script attempt to automate this process for you.
SYNOPSIS
Using the script:
myhost:~/ $ dns-dpf-expander --input_file zone.db
myhost:~/ $ ls
zone.db zone.db.new zone.db.bakUsing the module:
{
package MyDNSExpander;
use Net::DNS::SPF::Expander;
my $input_file = '/home/me/project/etc/zone.db';
my $expander = Net::DNS::SPF::Expander->new(
input_file => $input_file
);
my $string = $expander->write;
1;
}CONFIGURABLE ATTRIBUTES
input_file
This is the path and name of the zonefile whose SPF records you want to expand. It must be a valid Net::DNS::Zonefile zonefile.
output_file
The path and name of the output file. By default, we tack ".new" onto the end of the original filename.
backup_file
The path and name of the backup file. By default, we tack ".bak" onto the end of the original filename.
nameservers
A list of nameservers that will be passed to the resolver.
parsed_file
The Net::DNS::Zonefile object created from the input_file.
to_expand
An arrayref of regexes that we will expand. By default we expand a, mx, include, and redirect records. Configurable.
to_copy
An arrayref of regexes that we will simply copy over. By default we will copy ip4, ip6, ptr, and exists records. Configurable.
to_ignore
An arrayref of regexes that we will ignore. By default we ignore ?all, exp, v=spf1, and ~all.
maximum_record_length
We leave out the protocol declaration and the trailing ~all while we are expanding records, so we need to subtract their length from our length calculation.
ttl
Default time to live is 10 minutes. Configurable.
origin
The origin of the zonefile. We take it from the zonefile, or you can set it if you like.
PRIVATE ATTRIBUTES
_resource_records
An arrayref of all the Net::DNS::RR resource records found in the entire parsed_file.
_spf_records
An arrayref of the Net::DNS::RR::TXT or Net::DNS::RR::SPF records found in the entire parsed_file.
_resolver
What we use to do the DNS lookups and expand the records. A Net::DNS::Resolver object. You can still set environment variables if you want to change the nameserver it uses.
_expansions
This is a hashref representing the expanded SPF records. The keys are the names of the SPF records, and the values are hashrefs. Those are keyed on the include, and the values are arrayrefs of the expanded values. There is also a key called "elements" which gathers all the includes into one place, e.g.,
"*.test_zone.com" => {
"~all" => undef,
elements => [
"ip4:216.239.32.0/19", "ip4:64.233.160.0/19",
"ip4:66.249.80.0/20", "ip4:72.14.192.0/18",
...
],
"include:_spf.google.com" => [
"ip4:216.239.32.0/19",
"ip4:64.233.160.0/19",
...
],
"ip4:96.43.144.0/20" => [ "ip4:96.43.144.0/20" ],
"v=spf1" => undef
}They are alpha sorted in the final results for predictability in tests.
_lengths_of_expansions
We need to know how long the expanded record would be, because SPF records should be less than 256 bytes. If the expanded record would be longer than that, we need to split it into pieces.
_record_class
What sort of records are SPF records? IN records.
BUILDERS
_build_resolver
Return a Net::DNS::Resolver. Any nameservers will be passed through to the resolver.
_build_origin
Extract the origin from parsed_file.
_build_expansions
_build_backup_file
Tack a ".bak" onto the end of the input_file.
_build_output_file
Tack a ".new" onto the end of the input_file.
_build_parsed_file
Turn the Path::Tiny filehandle into a Net::DNS::Zonefile object, so that we can extract the SPF records.
_build_resource_records
Extract all the resource records from the Net::DNS::Zonefile.
_build__spf_records
Grep through the _resource_records to find the SPF records. They can be both "TXT" and "SPF" records, so we search for the protocol string, v=spf1.
_build__lengths_of_expansions
Calculate the length of each fully expanded SPF record, because they can't be longer than 256 bytes. We have to split them up into multiple records if they are.
PUBLIC METHODS
write
This is the only method you really need to call. This expands all your SPF records and writes out the new and the backup files.
Returns a scalar string of the data written to the file.
new_spf_records
In case you want to see how your records were expanded, this returns the hashref of Net::DNS::RR objects used to create the new records.
PRIVATE METHODS
_normalize_component
Each component of an SPF record has a prefix, like include:, mx:, etc. Here we chop off the prefix before performing the lookup on the value.
_perform_expansion
Expand a single SPF record component. This returns either undef or the full SPF record string from Net::DNS::RR::TXT->txtdata.
_expand_spf_component
Recursively call _perform_expansion for each component of the SPF record. This returns an array consisting of the component, e.g., include:salesforce.com, and an arrayref consisting of its full expansion, e.g.,
[
"ip4:216.239.32.0/19",
"ip4:64.233.160.0/19",
...
"ip6:2c0f:fb50:4000::/36"
]_expand
Create the _expansions hashref from which we generate new SPF records.
_extract_expansion_elements
Filter ignored elements from component expansions.
_new_records_from_arrayref
The full expansion of a given SPF record is contained in an arrayref, and if the length of the resulting new SPF record would be less than the maximum_record_length, we can use this method to make new Net::DNS::RR objects that will later be stringified for the new SPF record.
_new_records_from_partition
The full expansion of a given SPF record is contained in an arrayref, and if the length of the resulting new SPF record would be greater than the maximum_record_length, we have to jump through some hoops to properly split it into new SPF records. Because there will be more than one, and each needs to be less than the maximum_record_length. We do our partitioning here, and then call _new_records_from_arrayref on each of the resulting partitions.
_get_single_record_string
Stringify the Net::DNS::RR::TXT records when they will fit into a single SPF record.
_normalize_record_name
Net::DNS uses fully qualified record names, so that new SPF records will be named *.domain.com, and domain.com, instead of * and @. I prefer the symbols. This code replaces the fully qualified record names with symbols.
_get_multiple_record_strings
Whereas a single new SPF record needs to be concatenated from the stringified Net::DNS::RR::TXTs, and have the trailing ~all added, multiple new SPF records do not need that. They need to be given special _spf names that will then be included in "master" SPF records, and they don't need the trailing ~all.
_get_master_record_strings
Create our "master" SPF records that include the split _spf records created in _get_multiple_record_strings, e.g.,
* 600 IN TXT "v=spf1 include:_spf1.test_zone.com include:_spf2.test_zone.com ~all"_new_records_lines
Assemble the new DNS zonefile from the lines of the original, comment out the old SPF records, add in the new lines, and append the end of the original.
AUTHOR
Amiri Barksdale <amiri@campusexplorer.com>
CONTRIBUTORS
Neil Bowers <neil@bowers.com>
Marc Bradshaw <marc@marcbradshaw.net>
Karen Etheridge <ether@cpan.org>
Chris Weyl <cweyl@campusexplorer.com>
COPYRIGHT
Copyright (c) 2019 Campus Explorer, Inc.
LICENSE
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.