PHPMailer::DKIM_Add( string $headers_line, string $subject, string $body ): string

4988    public function DKIM_Add($headers_line, $subject, $body)4989    {4990        $DKIMsignatureType = 'rsa-sha256'; //Signature & hash algorithms4991        $DKIMcanonicalization = 'relaxed/simple'; //Canonicalization methods of header & body4992        $DKIMquery = 'dns/txt'; //Query method4993        $DKIMtime = time();4994        //Always sign these headers without being asked4995        //Recommended list from https://tools.ietf.org/html/rfc6376#section-5.4.14996        $autoSignHeaders = [4997            'from',4998            'to',4999            'cc',5000            'date',5001            'subject',5002            'reply-to',5003            'message-id',5004            'content-type',5005            'mime-version',5006            'x-mailer',5007        ];5008        if (stripos($headers_line, 'Subject') === false) {5009            $headers_line .= 'Subject: ' . $subject . static::$LE;5010        }5011        $headerLines = explode(static::$LE, $headers_line);5012        $currentHeaderLabel = '';5013        $currentHeaderValue = '';5014        $parsedHeaders = [];5015        $headerLineIndex = 0;5016        $headerLineCount = count($headerLines);5017        foreach ($headerLines as $headerLine) {5018            $matches = [];5019            if (preg_match('/^([^ \t]*?)(?::[ \t]*)(.*)$/', $headerLine, $matches)) {5020                if ($currentHeaderLabel !== '') {5021                    //We were previously in another header; This is the start of a new header, so save the previous one5022                    $parsedHeaders[] = ['label' => $currentHeaderLabel, 'value' => $currentHeaderValue];5023                }5024                $currentHeaderLabel = $matches[1];5025                $currentHeaderValue = $matches[2];5026            } elseif (preg_match('/^[ \t]+(.*)$/', $headerLine, $matches)) {5027                //This is a folded continuation of the current header, so unfold it5028                $currentHeaderValue .= ' ' . $matches[1];5029            }5030            ++$headerLineIndex;5031            if ($headerLineIndex >= $headerLineCount) {5032                //This was the last line, so finish off this header5033                $parsedHeaders[] = ['label' => $currentHeaderLabel, 'value' => $currentHeaderValue];5034            }5035        }5036        $copiedHeaders = [];5037        $headersToSignKeys = [];5038        $headersToSign = [];5039        foreach ($parsedHeaders as $header) {5040            //Is this header one that must be included in the DKIM signature?5041            if (in_array(strtolower($header['label']), $autoSignHeaders, true)) {5042                $headersToSignKeys[] = $header['label'];5043                $headersToSign[] = $header['label'] . ': ' . $header['value'];5044                if ($this->DKIM_copyHeaderFields) {5045                    $copiedHeaders[] = $header['label'] . ':' . //Note no space after this, as per RFC5046                        str_replace('|', '=7C', $this->DKIM_QP($header['value']));5047                }5048                continue;5049            }5050            //Is this an extra custom header we've been asked to sign?5051            if (in_array($header['label'], $this->DKIM_extraHeaders, true)) {5052                //Find its value in custom headers5053                foreach ($this->CustomHeader as $customHeader) {5054                    if ($customHeader[0] === $header['label']) {5055                        $headersToSignKeys[] = $header['label'];5056                        $headersToSign[] = $header['label'] . ': ' . $header['value'];5057                        if ($this->DKIM_copyHeaderFields) {5058                            $copiedHeaders[] = $header['label'] . ':' . //Note no space after this, as per RFC5059                                str_replace('|', '=7C', $this->DKIM_QP($header['value']));5060                        }5061                        //Skip straight to the next header5062                        continue 2;5063                    }5064                }5065            }5066        }5067        $copiedHeaderFields = '';