477 lines
13 KiB
PHP
477 lines
13 KiB
PHP
<?php
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namespace App\Classes\Protocol;
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use Illuminate\Support\Facades\Log;
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use Illuminate\Support\Str;
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use App\Classes\Protocol as BaseProtocol;
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use App\Classes\Sock\SocketClient;
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use App\Models\{Address,Domain,Mailer};
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/**
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* Respond to DNS queries and provide addresses to FTN nodes.
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* http://ftsc.org/docs/fts-5004.001
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*
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* This implementation doesnt support EDNS nor DNSSEC.
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*
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* If using bind, the following configuration is required:
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* options {
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* validate-except
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* {
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* "ftn";
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* };
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* };
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*
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* and optionally
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* server <IP ADDRESS> {
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* edns no;
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* };
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*/
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final class DNS extends BaseProtocol
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{
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private const LOGKEY = 'PD-';
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/* CONSTS */
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public const PORT = 53;
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private const DEFAULT_TTL = 86400;
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private const TLD = 'ftn';
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private BaseProtocol\DNS\Query $query;
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// DNS Response codes
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public const DNS_NOERROR = 0; // No error
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public const DNS_FORMERR = 1; // Format Error - The dns server could not read / understand the query
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public const DNS_SERVFAIL = 2; // Server Failure - There was a dns error with the dns server
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public const DNS_NAMEERR = 3; // Name Error - This specifies that the domain name in the query does not exist, it is only valid from an authoritative server
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public const DNS_NOTIMPLEMENTED = 4;// Not implemented - The requested query is not supported by the dns server
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public const DNS_REFUSED = 5; // Refused - The dns server refuses to process the dns query
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// DNS Query Classes
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public const DNS_QUERY_IN = 1; // Internet (this is the main one that is used)
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// DNS Query Types
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public const DNS_TYPE_A = 1; // A Records
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public const DNS_TYPE_NS = 2; // NS Records
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public const DNS_TYPE_CNAME = 5; // CNAME Records
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public const DNS_TYPE_SOA = 6; // SOA Records
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public const DNS_TYPE_MX = 15; // MX Records
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public const DNS_TYPE_TXT = 16; // TXT Records
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public const DNS_TYPE_AAAA = 28; // AAAA Records
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public const DNS_TYPE_SRV = 33; // SRV Records
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public const DNS_TYPE_OPT = 41; // OPT Records
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public const DNS_TYPE_DS = 43; // DS Records (Delegation signer RFC 4034)
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public function onConnect(SocketClient $client): ?int
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{
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// If our parent returns a PID, we've forked
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if (! parent::onConnect($client)) {
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Log::withContext(['pid'=>getmypid()]);
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$this->client = $client;
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$this->protocol_session();
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Log::info(sprintf('%s:= onConnect - Connection closed [%s]',self::LOGKEY,$client->address_remote));
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exit(0);
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}
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return NULL;
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}
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protected function protocol_init(): int
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{
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// N/A
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return 0;
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}
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/**
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* Handle a DNS query
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*
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* https://www.ietf.org/rfc/rfc1035.txt
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* https://www.ietf.org/rfc/rfc2308.txt
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* https://github.com/guyinatuxedo/dns-fuzzer/blob/master/dns.md
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*
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* labels 63 octets or less
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* names 255 octets or less
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* TTL positive values of a signed 32 bit number.
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* UDP messages 512 octets or less
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*
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* @param bool $force_queue Not used here
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* @return int
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* @throws \Exception
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*/
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public function protocol_session(bool $force_queue=FALSE): int
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{
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Log::debug(sprintf('%s:+ DNS Query',self::LOGKEY));
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try {
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$this->query = new BaseProtocol\DNS\Query($this->client->read(0,512));
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} catch (\Exception $e) {
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Log::notice(sprintf('%s:! Ignoring bad DNS query (%s)',self::LOGKEY,$e->getMessage()));
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return FALSE;
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}
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Log::info(sprintf('%s:= DNS Query from [%s] for [%s]',self::LOGKEY,$this->client->address_remote,$this->query->domain));
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// If the wrong class
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if ($this->query->class !== self::DNS_QUERY_IN) {
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Log::notice(sprintf('%s:! We only service Internet queries [%d]',self::LOGKEY,$this->query->class));
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return $this->reply(self::DNS_NOTIMPLEMENTED,[],$this->soa());
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}
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$dos = Domain::select(['id','name','dnsdomain'])->active();
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$ourdomains = $dos
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->pluck('name')
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->transform(function($item) { return sprintf('%s.%s',$item,self::TLD); })
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->merge($dos->pluck('dnsdomain'))
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->merge([self::TLD])
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->filter()
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->sortBy(function($item) { return substr_count($item,'.'); })
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->reverse();
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$query_domain = $this->query->domain;
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// If the query is not for our domains, return NAMEERR
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if (($do=$ourdomains->search(function ($item) use ($query_domain) { return preg_match("/${item}$/",$query_domain); })) === FALSE) {
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Log::alert(sprintf('%s:= DNS Query not for our domains',self::LOGKEY));
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return $this->nameerr();
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}
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// Action on the query type
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switch ($this->query->type) {
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// Return the SOA/NS records
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case self::DNS_TYPE_SOA:
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Log::info(sprintf('%s:= Returning SOA for [%s]',self::LOGKEY,$this->query->domain));
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return $this->reply(
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self::DNS_NOERROR,
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$this->soa(),
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[],
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[serialize($this->domain_split(config('fido.dns_ns'))) => self::DNS_TYPE_NS],
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);
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case self::DNS_TYPE_NS:
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Log::info(sprintf('%s:= Returning NS for [%s]',self::LOGKEY,$this->query->domain));
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return $this->reply(
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self::DNS_NOERROR,
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[serialize($this->domain_split(config('fido.dns_ns'))) => self::DNS_TYPE_NS]);
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// Respond to A/AAAA/CNAME queries, with value or NAMEERR
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case self::DNS_TYPE_CNAME:
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case self::DNS_TYPE_A:
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case self::DNS_TYPE_AAAA:
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case self::DNS_TYPE_SRV:
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case self::DNS_TYPE_TXT:
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Log::info(sprintf('%s:= Looking for record [%s] for [%s]',self::LOGKEY,$this->query->type,$this->query->domain));
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$labels = clone($this->query->labels);
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$mailer = '';
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// If this is a SRV record query
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if ($this->query->type === self::DNS_TYPE_SRV) {
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if ($labels->skip(1)->first() !== '_tcp')
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return $this->reply(self::DNS_NAMEERR);
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switch ($labels->first()) {
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case '_binkp':
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$mailer = Mailer::where('name','BINKP')->singleOrFail();
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break;
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case '_ifcico':
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$mailer = Mailer::where('name','EMSI')->singleOrFail();
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break;
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default:
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return $this->reply(self::DNS_NAMEERR);
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}
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$labels->shift(2);
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}
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// First check that it is a query we can answer
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// First label should be p.. or f..
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if (! is_null($p=$this->parse('p',$labels->first())))
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$labels->shift();
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else
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$p = 0;
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// We'll assume f0
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if (! is_null($f=$this->parse('f',$labels->first())))
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$labels->shift();
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else
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$f = 0;
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if (is_null($n=$this->parse('n',$labels->shift())))
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return $this->nameerr();
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if (is_null($z=$this->parse('z',$labels->shift())))
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return $this->nameerr();
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// If the query doesnt end with .ftn, then the remainder of the query is the domain name
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if (($labels->search(self::TLD) !== FALSE))
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$d = $labels->shift();
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else
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$d = '';
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// Make sure we have a root/base domain
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if (! $labels->count())
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return $this->nameerr();
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$rootdn = $labels->join('.');
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if (! $d && ($rootdn !== self::TLD))
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$d = Domain::where('dnsdomain',$rootdn)->single()?->name;
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$ao = Address::findFTN(sprintf('%d:%d/%d.%d@%s',$z,$n,$f,$p,$d));
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// Check we have the right record
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if ((! $ao) || (($rootdn !== self::TLD) && ((! $ao->zone->domain->dnsdomain) || ($ao->zone->domain->dnsdomain !== $rootdn)))) {
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Log::alert(sprintf('%s:= No DNS record for [%d:%d/%d.%d@%s]',self::LOGKEY,$z,$n,$f,$p,$d));
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return $this->nameerr();
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}
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switch ($this->query->type) {
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case self::DNS_TYPE_SRV:
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Log::info(sprintf('%s:= Returning [%s] for DNS query [%s]',self::LOGKEY,$ao->system->address,$ao->ftn));
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if (($ao->system->address) && ($xx=$ao->system->mailers->where('id',$mailer->id)->pop())) {
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return $this->reply(
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self::DNS_NOERROR,
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[serialize([
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0, // priority
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1, // weight
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$xx->pivot->port,
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$this->domain_split($ao->system->address),
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]) => self::DNS_TYPE_SRV]);
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} else {
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return $this->nodata();
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}
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case self::DNS_TYPE_TXT:
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Log::info(sprintf('%s:= Returning [%s] for DNS query [%s]',self::LOGKEY,$ao->system->name,$ao->ftn));
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return $this->reply(
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self::DNS_NOERROR,
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[serialize($ao->system->name) => self::DNS_TYPE_TXT]);
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default:
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Log::info(sprintf('%s:= Returning [%s] for DNS query [%s]',self::LOGKEY,$ao->system->address,$ao->ftn));
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return (! $ao->system->address)
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? $this->nodata()
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: $this->reply(
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self::DNS_NOERROR,
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[serialize($this->domain_split($ao->system->address)) => self::DNS_TYPE_CNAME]);
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}
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// Other attributes return NOTIMPL
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default:
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Log::notice(sprintf('%s:! We dont support DNS query types [%d]',self::LOGKEY,$this->query->type));
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return $this->reply(self::DNS_NOTIMPLEMENTED,[],$this->soa());
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}
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}
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/**
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* Return a compression string for a specific offset
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*
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* @param int $offset
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* @return string
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*/
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private function compress(int $offset): string
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{
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return pack('n',$offset | (3 << 14));
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}
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/**
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* Split a domain into a DNS domain string
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*
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* @param string $domain
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* @return string
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*/
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private function domain_split(string $domain): string
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{
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$a = '';
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foreach (explode('.',$domain) as $item)
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$a .= pack('C',strlen($item)).$item;
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$a .= "\x00";
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return $a;
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}
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private function nameerr(): int
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{
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Log::notice(sprintf('%s:! DNS query for a resource we dont manage [%s]',self::LOGKEY,$this->query->domain));
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return $this->reply(self::DNS_NAMEERR,[],$this->soa());
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}
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private function nodata(): int
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{
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Log::notice(sprintf('%s:! DNS query for a resource we dont manage [%s] in our zone(s)',self::LOGKEY,$this->query->domain));
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return $this->reply(self::DNS_NOERROR,[],$this->soa());
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}
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/**
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* Parse a label for a fido address nibble
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*
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* @param string $prefix
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* @param string $label
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* @return string|null
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*/
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private function parse(string $prefix,string $label): ?string
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{
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$m = [];
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return (preg_match('/^'.$prefix.'([0-9]+)+/',$label,$m) && ($m[1] <= Address::ADDRESS_FIELD_MAX))
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? $m[1]
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: NULL;
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}
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/**
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* Return a DNS response
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*
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* @param int $code
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* @param array $answer
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* @param array $authority
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* @param array $additional
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* @return bool
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* @throws \Exception
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*/
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private function reply(int $code,array $answer=[],array $authority=[],array $additional=[]): bool
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{
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$header = (1 << 15); // 1b: Query/Response
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$header |= ($this->query->header & 0xf) << 11; // 4b: Opcode
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$header |= (1 << 10); // 1b: Authoritative Answer
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$header |= (0 << 9); // 1b: Truncated
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$header |= ((($this->query->header >> 8) & 1) << 8); // 1b: Recursion Desired (in queries)
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$header |= (0 << 7); // 1b: Recursion Available (in responses)
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$header |= (0 << 4); // 3b: Zero (future, should be zero)
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$header |= ($code & 0xf); // 4b: Result Code
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$q = $this->query->dns ? 1 : 0;
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$r = count($answer);
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$nscount = count($authority);
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$arcount = count($additional);
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$reply = pack('nnnnnn',$this->query->id,$header,$q,$r,$nscount,$arcount);
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// Return the answer
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if ($r) {
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// Question
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$reply .= $this->query->dns;
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// @todo In the case we return a CNAME and an A record, this should reference the CNAME domain when returning the A record
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foreach ($answer as $item => $type) {
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$rr = $this->rr($this->compress(12),unserialize($item),$type,self::DEFAULT_TTL);
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$reply .= $rr;
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}
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} else {
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$reply .= $this->query->dns;
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}
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foreach ($authority as $item => $type) {
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$rr = $this->rr($this->compress(12),unserialize($item),$type,self::DEFAULT_TTL);
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$reply .= $rr;
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}
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foreach ($additional as $item => $type) {
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$rr = $this->rr($this->compress(12),unserialize($item),$type,self::DEFAULT_TTL);
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$reply .= $rr;
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}
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if (! $this->client->send($reply,0)) {
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Log::error(sprintf('%s:! Error [%s] sending DNS reply to [%s:%d]',
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self::LOGKEY,
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socket_strerror(socket_last_error()),
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$this->client->address_remote,
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$this->client->port_remote
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));
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return FALSE;
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}
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return TRUE;
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}
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/**
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* Return a DNS Resource Record
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*
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* @param string $query - Domain in the query
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* @param mixed $ars - Answer resources
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* @param int $type - Resource type
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* @param int $ttl - Time to live
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* @return string
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*/
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private function rr(string $query,mixed $ars,int $type,int $ttl): string
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{
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// Reference the domain query in the question
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$reply = $query;
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// Record Type
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$reply .= pack('n',$type);
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// Internet
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$reply .= pack('n',self::DNS_QUERY_IN);
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// TTL
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$reply .= pack('N',$ttl);
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// Answer
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$a = '';
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switch ($type) {
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case self::DNS_TYPE_NS:
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case self::DNS_TYPE_CNAME:
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case self::DNS_TYPE_A:
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case self::DNS_TYPE_AAAA:
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$a .= $ars;
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break;
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case self::DNS_TYPE_SOA:
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$a .= $ars[0];
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$a .= $ars[1];
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$a .= pack('NNNNN',$ars[2],$ars[3],$ars[4],$ars[5],$ars[6]);
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break;
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case self::DNS_TYPE_SRV:
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$a .= pack('nnn',$ars[0],$ars[1],$ars[2]);
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$a .= $ars[3];
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break;
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case self::DNS_TYPE_TXT:
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$a .= pack('C',strlen($ars)).$ars;
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break;
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}
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$reply .= pack('n',strlen($a)).$a;
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return $reply;
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}
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private function soa(): array
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{
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return
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[serialize([
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$this->domain_split(config('fido.dns_ns')),
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$this->domain_split(Str::replace('@','.',config('app.mail.mail_from','nobody@'.gethostname()))),
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1, // Serial
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self::DEFAULT_TTL, // Refresh
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self::DEFAULT_TTL, // Retry
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self::DEFAULT_TTL*7,// Expire
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self::DEFAULT_TTL // Minimum cache
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]) => self::DNS_TYPE_SOA];
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}
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} |