+ $hdr_s .= $sLine;
+ break;
+ case 'To':
+ case 'Cc':
+ case 'Bcc':
+ case 'From':
+ $hdr_s .= $header[$i];
+ break;
+ default: $hdr_s .= $this->foldLine($header[$i], 78); break;
+ }
+ }
+ $header = $hdr_s;
+ $header .= $rn; /* One blank line to separate header and body */
+ $raw_length += strlen($header);
+ return $header;
+ }
+
+ /**
+ * Fold header lines per RFC 2822/2.2.3 and RFC 822/3.1.1
+ *
+ * Herein "soft" folding/wrapping (with whitespace tokens) is
+ * what we refer to as the preferred method of wrapping - that
+ * which we'd like to do within the $soft_wrap limit, but if
+ * not possible, we will try to do as soon as possible after
+ * $soft_wrap up to the $hard_wrap limit. Encoded words don't
+ * need to be detected in this phase, since they cannot contain
+ * spaces.
+ *
+ * "Hard" folding/wrapping (with "hard" tokens) is what we refer
+ * to as less ideal wrapping that will be done to keep within
+ * the $hard_wrap limit. This adds other syntactical breaking
+ * elements such as commas and encoded words.
+ *
+ * @param string $header The header content being folded
+ * @param integer $soft_wrap The desirable maximum line length
+ * (OPTIONAL; default is 78, per RFC)
+ * @param string $indent Wrapped lines will already have
+ * whitespace following the CRLF wrap,
+ * but you can add more indentation (or
+ * whatever) with this. The use of this
+ * parameter is DISCOURAGED, since it
+ * can corrupt the redisplay (unfolding)
+ * of headers whose content is space-
+ * sensitive, like subjects, etc.
+ * (OPTIONAL; default is an empty string)
+ * @param string $hard_wrap The absolute maximum line length
+ * (OPTIONAL; default is 998, per RFC)
+ *
+ * @return string The folded header content, with a trailing CRLF.
+ *
+ */
+ function foldLine($header, $soft_wrap=78, $indent='', $hard_wrap=998) {
+
+ // the "hard" token list can be altered if desired,
+ // for example, by adding ":"
+ // (in the future, we can take optional arguments
+ // for overriding or adding elements to the "hard"
+ // token list if we want to get fancy)
+ //
+ // the order of these is significant - preferred
+ // fold points should be listed first
+ //
+ // it is advised that the "=" always come first
+ // since it also finds encoded words, thus if it
+ // comes after some other token that happens to
+ // fall within the encoded word, the encoded word
+ // could be inadvertently broken in half, which
+ // is not allowable per RFC
+ //
+ $hard_break_tokens = array(
+ '=', // includes encoded word detection
+ ',',
+ ';',
+ );
+
+ // the order of these is significant too
+ //
+ $whitespace = array(
+ ' ',
+ "\t",
+ );
+
+ $CRLF = "\r\n";
+
+ $folded_header = '';
+
+ // if using an indent string, reduce wrap limits by its size
+ //
+ if (!empty($indent)) {
+ $soft_wrap -= strlen($indent);
+ $hard_wrap -= strlen($indent);
+ }
+
+ while (strlen($header) > $soft_wrap) {
+
+ $soft_wrapped_line = substr($header, 0, $soft_wrap);
+
+ // look for a token as close to the end of the soft wrap limit as possible
+ //
+ foreach ($whitespace as $token) {
+
+ // note that this if statement also fails when $pos === 0,
+ // which is intended, since blank lines are not allowed
+ //
+ if ($pos = strrpos($soft_wrapped_line, $token))
+ {
+ $new_fold = substr($header, 0, $pos);
+
+ // make sure proposed fold doesn't create a blank line
+ //
+ if (!trim($new_fold)) continue;
+
+ // with whitespace breaks, we fold BEFORE the token
+ //
+ $folded_header .= $new_fold . $CRLF . $indent;
+ $header = substr($header, $pos);
+
+ // ready for next while() iteration
+ //
+ continue 2;
+
+ }
+
+ }
+
+ // we were unable to find a wrapping point within the soft
+ // wrap limit, so now we'll try to find the first possible
+ // soft wrap point within the hard wrap limit
+ //
+ $hard_wrapped_line = substr($header, 0, $hard_wrap);
+
+ // look for a *SOFT* token as close to the
+ // beginning of the hard wrap limit as possible
+ //
+ foreach ($whitespace as $token) {
+
+ // use while loop instead of if block because it
+ // is possible we don't want the first one we find
+ //
+ $pos = $soft_wrap - 1; // -1 is corrected by +1 on next line
+ while ($pos = strpos($hard_wrapped_line, $token, $pos + 1))
+ {
+
+ $new_fold = substr($header, 0, $pos);
+
+ // make sure proposed fold doesn't create a blank line
+ //
+ if (!trim($new_fold)) continue;
+
+ // with whitespace breaks, we fold BEFORE the token
+ //
+ $folded_header .= $new_fold . $CRLF . $indent;
+ $header = substr($header, $pos);
+
+ // ready for next outter while() iteration
+ //
+ continue 3;
+
+ }
+
+ }
+
+ // we were still unable to find a soft wrapping point within
+ // both the soft and hard wrap limits, so if the length of
+ // what is left is no more than the hard wrap limit, we'll
+ // simply take the whole thing
+ //
+ if (strlen($header) <= strlen($hard_wrapped_line))
+ break;
+
+ // otherwise, we can't quit yet - look for a "hard" token
+ // as close to the end of the hard wrap limit as possible
+ //
+ foreach ($hard_break_tokens as $token) {
+
+ // note that this if statement also fails when $pos === 0,
+ // which is intended, since blank lines are not allowed
+ //
+ if ($pos = strrpos($hard_wrapped_line, $token))
+ {
+
+ // if we found a "=" token, we must determine whether,
+ // if it is part of an encoded word, it is the beginning
+ // or middle of one, where we need to readjust $pos a bit
+ //
+ if ($token == '=') {
+
+ // if we found the beginning of an encoded word,
+ // we want to break BEFORE the token
+ //
+ if (preg_match('/^(=\?([^?]*)\?(Q|B)\?([^?]*)\?=)/Ui',
+ substr($header, $pos))) {
+ $pos--;
+ }
+
+ // check if we found this token in the *middle*
+ // of an encoded word, in which case we have to
+ // ignore it, pushing back to the token that
+ // starts the encoded word instead
+ //
+ // of course, this is only possible if there is
+ // more content after the next hard wrap
+ //
+ // then look for the end of an encoded word in
+ // the next part (past the next hard wrap)
+ //
+ // then see if it is in fact part of a legitimate
+ // encoded word
+ //
+ else if (strlen($header) > $hard_wrap
+ && ($end_pos = strpos(substr($header, $hard_wrap), '?=')) !== FALSE
+ && preg_match('/(=\?([^?]*)\?(Q|B)\?([^?]*)\?=)$/Ui',
+ substr($header, 0, $hard_wrap + $end_pos + 2),
+ $matches)) {
+
+ $pos = $hard_wrap + $end_pos + 2 - strlen($matches[1]) - 1;
+
+ }
+