From: pdontthink Date: Fri, 3 Apr 2009 01:21:07 +0000 (+0000) Subject: Rewrite foldLine(). The old version *might* have been fixable, but it contained... X-Git-Url: https://vcs.fsf.org/?a=commitdiff_plain;h=9bcf508d54a578246d5df010bbb4b93740ec3197;p=squirrelmail.git Rewrite foldLine(). The old version *might* have been fixable, but it contained several bad assumptions, RFC misunderstandings and design problems. The new one is better documented if nothing else. PLEASE PLEASE PLEASE TEST THIS. This is a candidate for backporting to STABLE since it fixes some buggy behaviors - see #2501008 and #1951776 and others git-svn-id: https://svn.code.sf.net/p/squirrelmail/code/trunk/squirrelmail@13505 7612ce4b-ef26-0410-bec9-ea0150e637f0 --- diff --git a/class/deliver/Deliver.class.php b/class/deliver/Deliver.class.php index 8a53e0f4..80f62976 100644 --- a/class/deliver/Deliver.class.php +++ b/class/deliver/Deliver.class.php @@ -491,7 +491,7 @@ class Deliver { $cnt = count($header); $hdr_s = ''; for ($i = 0 ; $i < $cnt ; $i++) { - $hdr_s .= $this->foldLine($header[$i], 78,str_pad('',4)); + $hdr_s .= $this->foldLine($header[$i], 78); } $header = $hdr_s; $header .= $rn; /* One blank line to separate mimeheader and body-entity */ @@ -731,7 +731,7 @@ class Deliver { case 'From': $hdr_s .= $header[$i]; break; - default: $hdr_s .= $this->foldLine($header[$i], 78, str_pad('',4)); break; + default: $hdr_s .= $this->foldLine($header[$i], 78); break; } } $header = $hdr_s; @@ -741,97 +741,270 @@ class Deliver { } /** - * function foldLine - for cleanly folding of headerlines - * - * @param string $line - * @param integer $length length to fold the line at - * @param string $pre prefix the line with... - * - * @return string $line folded line with trailing CRLF - */ - function foldLine($line, $length, $pre='') { - $line = substr($line,0, -2); - $length -= 2; /* do not fold between \r and \n */ - $cnt = strlen($line); - if ($cnt > $length) { /* try folding */ - $fold_string = "\r\n " . $pre; - $bFirstFold = false; - $aFoldLine = array(); - while (strlen($line) > $length) { - $fold = false; - /* handle encoded parts */ - if (preg_match('/(=\?([^?]*)\?(Q|B)\?([^?]*)\?=)(\s+|.*)/Ui',$line,$regs)) { - $fold_tmp = $regs[1]; - if (!trim($regs[5])) { - $fold_tmp .= $regs[5]; - } - $iPosEnc = strpos($line,$fold_tmp); - $iLengthEnc = strlen($fold_tmp); - $iPosEncEnd = $iPosEnc+$iLengthEnc; - if ($iPosEnc < $length && (($iPosEncEnd) > $length)) { - $fold = true; - /* fold just before the start of the encoded string */ - if ($iPosEnc) { - $aFoldLine[] = substr($line,0,$iPosEnc); - } - $line = substr($line,$iPosEnc); - if (!$bFirstFold) { - $bFirstFold = true; - $length -= strlen($fold_string); - } - if ($iLengthEnc > $length) { /* place the encoded - string on a separate line and do not fold inside it*/ - /* minimize foldstring */ - $fold_string = "\r\n "; - $aFoldLine[] = substr($line,0,$iLengthEnc); - $line = substr($line,$iLengthEnc); + * 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))) { + $pos--; } - } else if ($iPosEnc < $length) { /* the encoded string fits into the foldlength */ - /*remainder */ - $sLineRem = substr($line,$iPosEncEnd,$length - $iPosEncEnd); - if (preg_match('/^(=\?([^?]*)\?(Q|B)\?([^?]*)\?=)(.*)/Ui',$sLineRem) || !preg_match('/[=,;\s]/',$sLineRem)) { - /*impossible to fold clean in the next part -> fold after the enc string */ - $aFoldLine[] = substr($line,0,$iPosEncEnd); - $line = substr($line,$iPosEncEnd); - $fold = true; - if (!$bFirstFold) { - $bFirstFold = true; - $length -= strlen($fold_string); - } + + // 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; + } - } - } - if (!$fold) { - $line_tmp = substr($line,0,$length); - $iFoldPos = false; - /* try to fold at logical places */ - switch (true) - { - case ($iFoldPos = strrpos($line_tmp,',')): break; - case ($iFoldPos = strrpos($line_tmp,';')): break; - case ($iFoldPos = strrpos($line_tmp,' ')): break; - case ($iFoldPos = strrpos($line_tmp,'=')): break; - default: break; - } - if (!$iFoldPos) { /* clean folding didn't work */ - $iFoldPos = $length; } - $aFoldLine[] = substr($line,0,$iFoldPos+1); - $line = substr($line,$iFoldPos+1); - if (!$bFirstFold) { - $bFirstFold = true; - $length -= strlen($fold_string); + + // $pos could have been changed; make sure it's + // not at the beginning of the line, as blank + // lines are not allowed + // + if ($pos === 0) continue; + + // we are dealing with a simple token break... + // + // for non-whitespace breaks, we fold AFTER the token + // and add a space after the fold if not immediately + // followed by a whitespace character in the next part + // + $folded_header .= substr($header, 0, $pos + 1) . $CRLF; + + // don't go beyond end of $header, though + // + if (strlen($header) > $pos + 1) { + $header = substr($header, $pos + 1); + if (!in_array($header{0}, $whitespace)) + $header = ' ' . $indent . $header; + } else { + $header = ''; } + + // ready for next while() iteration + // + continue 2; + } + } - /*$reconstruct the line */ - if ($line) { - $aFoldLine[] = $line; + + // finally, we just couldn't find anything to fold on, so we + // have to just cut it off at the hard limit + // + $folded_header .= $hard_wrapped_line . $CRLF; + + // is there more? + // + if (strlen($header) > strlen($hard_wrapped_line)) { + $header = substr($header, strlen($hard_wrapped_line)); + if (!in_array($header{0}, $whitespace)) + $header = ' ' . $indent . $header; + } else { + $header = ''; } - $line = implode($fold_string,$aFoldLine); + } - return $line."\r\n"; + + + // add any left-overs + // + $folded_header .= $header; + + + // make sure it ends with a CRLF + // + if (substr($folded_header, -2) != $CRLF) $folded_header .= $CRLF; + + + return $folded_header; } /**