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.bak
Using 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.
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
_input_file
The IO::All object created from the input_file.
_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
}
_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.
_build_origin
Extract the origin from parsed_file.
_build_expansions
_build_backup_file
Tack a ".bak" onto the end of the input_file.
_build__input_file
Turn the string input_file into a filehandle with IO::All.
_build_output_file
Tack a ".new" onto the end of the input_file.
_build_parsed_file
Turn the IO::All 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 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 _spf1.test_zone.com _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>
COPYRIGHT
Copyright (c) 2013 the Net::DNS::SPF::Expander "AUTHOR" listed above.
LICENSE
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
SEE ALSO
Net::DNS
Net::DNS::RR::TXT
MooseX::Getopt