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package MIME::Parser::Filer; =head1 NAME MIME::Parser::Filer - manage file-output of the parser =head1 SYNOPSIS Before reading further, you should see L<MIME::Parser> to make sure that you understand where this module fits into the grand scheme of things. Go on, do it now. I'll wait. Ready? Ok... now read L<"DESCRIPTION"> below, and everything else should make sense. =head2 Public interface ### Create a "filer" of the desired class: my $filer = MIME::Parser::FileInto->new($dir); my $filer = MIME::Parser::FileUnder->new($basedir); ... ### Want added security? Don't let outsiders name your files: $filer->ignore_filename(1); ### Prepare for the parsing of a new top-level message: $filer->init_parse; ### Return the path where this message's data should be placed: $path = $filer->output_path($head); =head2 Semi-public interface These methods might be overridden or ignored in some subclasses, so they don't all make sense in all circumstances: ### Tweak the mapping from content-type to extension: $emap = $filer->output_extension_map; $emap->{"text/html"} = ".htm"; =head1 DESCRIPTION =head2 How this class is used when parsing When a MIME::Parser decides that it wants to output a file to disk, it uses its "Filer" object -- an instance of a MIME::Parser::Filer subclass -- to determine where to put the file. Every parser has a single Filer object, which it uses for all parsing. You can get the Filer for a given $parser like this: $filer = $parser->filer; At the beginning of each C<parse()>, the filer's internal state is reset by the parser: $parser->filer->init_parse; The parser can then get a path for each entity in the message by handing that entity's header (a MIME::Head) to the filer and having it do the work, like this: $new_file = $parser->filer->output_path($head); Since it's nice to be able to clean up after a parse (especially a failed parse), the parser tells the filer when it has actually used a path: $parser->filer->purgeable($new_file); Then, if you want to clean up the files which were created for a particular parse (and also any directories that the Filer created), you would do this: $parser->filer->purge; =head2 Writing your own subclasses There are two standard "Filer" subclasses (see below): B<MIME::Parser::FileInto>, which throws all files from all parses into the same directory, and B<MIME::Parser::FileUnder> (preferred), which creates a subdirectory for each message. Hopefully, these will be sufficient for most uses, but just in case... The only method you have to override is L<output_path()|/output_path>: $filer->output_path($head); This method is invoked by MIME::Parser when it wants to put a decoded message body in an output file. The method should return a path to the file to create. Failure is indicated by throwing an exception. The path returned by C<output_path()> should be "ready for open()": any necessary parent directories need to exist at that point. These directories can be created by the Filer, if course, and they should be marked as B<purgeable()> if a purge should delete them. Actually, if your issue is more I<where> the files go than what they're named, you can use the default L<output_path()|/output_path> method and just override one of its components: $dir = $filer->output_dir($head); $name = $filer->output_filename($head); ... =head1 PUBLIC INTERFACE =head2 MIME::Parser::Filer This is the abstract superclass of all "filer" objects. =over 4 =cut use strict; ### Kit modules: use MIME::Tools qw(:msgtypes); use File::Spec; use File::Path qw(rmtree); use MIME::WordDecoder; ### Output path uniquifiers: my $GFileNo = 0; my $GSubdirNo = 0; ### Map content-type to extension. ### If we can't map "major/minor", we try "major/*", then use "*/*". my %DefaultTypeToExt = qw( application/andrew-inset .ez application/octet-stream .bin application/oda .oda application/pdf .pdf application/pgp .pgp application/postscript .ps application/rtf .rtf application/x-bcpio .bcpio application/x-chess-pgn .pgn application/x-cpio .cpio application/x-csh .csh application/x-dvi .dvi application/x-gtar .gtar application/x-gunzip .gz application/x-hdf .hdf application/x-latex .latex application/x-mif .mif application/x-netcdf .cdf application/x-netcdf .nc application/x-sh .sh application/x-shar .shar application/x-sv4cpio .sv4cpio application/x-sv4crc .sv4crc application/x-tar .tar application/x-tcl .tcl application/x-tex .tex application/x-texinfo .texi application/x-troff .roff application/x-troff .tr application/x-troff-man .man application/x-troff-me .me application/x-troff-ms .ms application/x-ustar .ustar application/x-wais-source .src application/zip .zip audio/basic .snd audio/ulaw .au audio/x-aiff .aiff audio/x-wav .wav image/gif .gif image/ief .ief image/jpeg .jpg image/png .png image/xbm .xbm image/tiff .tif image/x-cmu-raster .ras image/x-portable-anymap .pnm image/x-portable-bitmap .pbm image/x-portable-graymap .pgm image/x-portable-pixmap .ppm image/x-rgb .rgb image/x-xbitmap .xbm image/x-xpixmap .xpm image/x-xwindowdump .xwd text/* .txt text/html .html text/plain .txt text/richtext .rtx text/tab-separated-values .tsv text/x-setext .etx text/x-vcard .vcf video/mpeg .mpg video/quicktime .mov video/x-msvideo .avi video/x-sgi-movie .movie message/* .msg */* .dat ); #------------------------------ =item new INITARGS... I<Class method, constructor.> Create a new outputter for the given parser. Any subsequent arguments are given to init(), which subclasses should override for their own use (the default init does nothing). =cut sub new { my ($class, @initargs) = @_; my $self = bless { MPF_Prefix => "msg", MPF_Dir => ".", MPF_Ext => { %DefaultTypeToExt }, MPF_Purgeable => [], ### files created by the last parse MPF_MaxName => 80, ### max filename before treated as evil MPF_TrimRoot => 14, ### trim root to this length MPF_TrimExt => 3, ### trim extension to this length }, $class; $self->init(@initargs); $self; } sub init { ### no-op } #------------------------------ # My PID, but untainted # sub untainted_pid { if ($$ =~ /^(\d+)$/) { return $1; } # Can't happen... return "0"; } #------------------------------ # # cleanup_dir # # Instance method, private. # Cleanup a directory, defaulting empty to "." # sub cleanup_dir { my ($self, $dir) = @_; $dir = '.' if (!defined($dir) || ($dir eq '')); # coerce empty to "." $dir = '/.' if ($dir eq '/'); # coerce "/" so "$dir/$filename" works $dir =~ s|/$||; # be nice: get rid of any trailing "/" $dir; } #------------------------------ =item results RESULTS I<Instance method.> Link this filer to a MIME::Parser::Results object which will tally the messages. Notice that we avoid linking it to the parser to avoid circular reference! =cut sub results { my ($self, $results) = @_; $self->{MPF_Results} = $results if (@_ > 1); $self->{MPF_Results}; } ### Log debug messages: sub debug { my $self = shift; if (MIME::Tools->debugging()) { if ($self->{MPF_Results}) { unshift @_, $self->{MPF_Results}->indent; $self->{MPF_Results}->msg($M_DEBUG, @_); } MIME::Tools::debug(@_); } } ### Log warning messages: sub whine { my $self = shift; if ($self->{MPF_Results}) { unshift @_, $self->{MPF_Results}->indent; $self->{MPF_Results}->msg($M_WARNING, @_); } MIME::Tools::whine(@_); } #------------------------------ =item init_parse I<Instance method.> Prepare to start parsing a new message. Subclasses should always be sure to invoke the inherited method. =cut sub init_parse { my $self = shift; $self->{MPF_Purgeable} = []; } #------------------------------ =item evil_filename FILENAME I<Instance method.> Is this an evil filename; i.e., one which should not be used in generating a disk file name? It is if any of these are true: * it is empty or entirely whitespace * it contains leading or trailing whitespace * it is a string of dots: ".", "..", etc. * it contains characters not in the set: "A" - "Z", "a" - "z", "0" - "9", "-", "_", "+", "=", ".", ",", "@", "#", "$", and " ". * it is too long If you just want to change this behavior, you should override this method in the subclass of MIME::Parser::Filer that you use. B<Warning:> at the time this method is invoked, the FILENAME has already been unmime'd into the local character set. If you're using any character set other than ASCII, ISO-8859-*, or UTF-8, the interpretation of the "path" characters might be very different, and you will probably need to override this method. See L<MIME::WordDecoder/unmime> for more details. B<Note:> subclasses of MIME::Parser::Filer which override output_path() might not consult this method; note, however, that the built-in subclasses do consult it. I<Thanks to Andrew Pimlott for finding a real dumb bug in the original version. Thanks to Nickolay Saukh for noting that evil is in the eye of the beholder.> =cut sub evil_filename { my ($self, $name) = @_; $self->debug("is this evil? '$name'"); return 1 if (!defined($name) or ($name eq '')); ### empty return 1 if ($name =~ m{(^\s)|(\s+\Z)}); ### leading/trailing whitespace return 1 if ($name =~ m{^\.+\Z}); ### dots return 1 if ($name =~ /[^-A-Z0-9_+=.,@\#\$\% ]/i); # Only allow good chars return 1 if ($self->{MPF_MaxName} and (length($name) > $self->{MPF_MaxName})); $self->debug("it's ok"); 0; } #------------------------------ =item exorcise_filename FILENAME I<Instance method.> If a given filename is evil (see L</evil_filename>) we try to rescue it by performing some basic operations: shortening it, removing bad characters, etc., and checking each against evil_filename(). Returns the exorcised filename (which is guaranteed to not be evil), or undef if it could not be salvaged. B<Warning:> at the time this method is invoked, the FILENAME has already been unmime'd into the local character set. If you're using anything character set other than ASCII, ISO-8859-*, or UTF-8, the interpretation of the "path" characters might be very very different, and you will probably need to override this method. See L<MIME::WordDecoder/unmime> for more details. =cut sub exorcise_filename { my ($self, $fname) = @_; ### Isolate to last path element: my $last = $fname; ### Path separators are / or \ $last =~ s{^.*[/\\]}{}; ### Convert semi-evil characters to underscores $last =~ s/[\/\\\[\]:]/_/g; if ($last and !$self->evil_filename($last)) { $self->debug("looks like I can use the last path element"); return $last; } ### Break last element into root and extension, and truncate: my ($root, $ext) = (($last =~ /^(.*)\.([^\.]+)\Z/) ? ($1, $2) : ($last, '')); ### Delete leading and trailing whitespace $root =~ s/^\s+//; $ext =~ s/\s+$//; $root = substr($root, 0, ($self->{MPF_TrimRoot} || 14)); $ext = substr($ext, 0, ($self->{MPF_TrimExt} || 3)); $ext =~ /^\w+$/ or $ext = "dat"; my $trunc = $root . ($ext ? ".$ext" : ''); if (!$self->evil_filename($trunc)) { $self->debug("looks like I can use the truncated last path element"); return $trunc; } ### Remove all bad characters $trunc =~ s/([^-A-Z0-9_+=.,@\#\$ ])/sprintf("%%%02X", unpack("C", $1))/ige; if (!$self->evil_filename($trunc)) { $self->debug("looks like I can use a munged version of the truncated last path element"); return $trunc; } ### Hope that works: undef; } #------------------------------ =item find_unused_path DIR, FILENAME I<Instance method, subclasses only.> We have decided on an output directory and tentative filename, but there is a chance that it might already exist. Keep adding a numeric suffix "-1", "-2", etc. to the filename until an unused path is found, and then return that path. The suffix is actually added before the first "." in the filename is there is one; for example: picture.gif archive.tar.gz readme picture-1.gif archive-1.tar.gz readme-1 picture-2.gif archive-2.tar.gz readme-2 ... ... ... picture-10.gif ... This can be a costly operation, and risky if you don't want files renamed, so it is in your best interest to minimize situations where these kinds of collisions occur. Unfortunately, if a multipart message gives all of its parts the same recommended filename, and you are placing them all in the same directory, this method might be unavoidable. =cut sub find_unused_path { my ($self, $dir, $fname) = @_; my $i = 0; while (1) { ### Create suffixed name (from filename), and see if we can use it: my $suffix = ($i ? "-$i" : ""); my $sname = $fname; $sname =~ s/^(.*?)(\.|\Z)/$1$suffix$2/; my $path = File::Spec->catfile($dir, $sname); if (! -e $path) { ### it's good! $i and $self->whine("collision with $fname in $dir: using $path"); return $path; } $self->debug("$path already taken"); } continue { ++$i; } } #------------------------------ =item ignore_filename [YESNO] I<Instance method.> Return true if we should always ignore recommended filenames in messages, choosing instead to always generate our own filenames. With argument, sets this value. B<Note:> subclasses of MIME::Parser::Filer which override output_path() might not honor this setting; note, however, that the built-in subclasses honor it. =cut sub ignore_filename { my $self = shift; $self->{MPF_IgnoreFilename} = $_[0] if @_; $self->{MPF_IgnoreFilename}; } #------------------------------ =item output_dir HEAD I<Instance method.> Return the output directory for the given header. The default method returns ".". =cut sub output_dir { my ($self, $head) = @_; return "."; } #------------------------------ =item output_filename HEAD I<Instance method, subclasses only.> A given recommended filename was either not given, or it was judged to be evil. Return a fake name, possibly using information in the message HEADer. Note that this is just the filename, not the full path. Used by L<output_path()|/output_path>. If you're using the default C<output_path()>, you probably don't need to worry about avoiding collisions with existing files; we take care of that in L<find_unused_path()|/find_unused_path>. =cut sub output_filename { my ($self, $head) = @_; ### Get the recommended name: my $recommended = $head->recommended_filename; ### Get content type: my ($type, $subtype) = split m{/}, $head->mime_type; $subtype ||= ''; ### Get recommended extension, being quite conservative: my $recommended_ext = (($recommended and ($recommended =~ m{(\.\w+)\Z})) ? $1 : undef); ### Try and get an extension, honoring a given one first: my $ext = ($recommended_ext || $self->{MPF_Ext}{"$type/$subtype"} || $self->{MPF_Ext}{"$type/*"} || $self->{MPF_Ext}{"*/*"} || ".dat"); ### Get a prefix: ++$GFileNo; return ($self->output_prefix . "-" . untainted_pid() . "-$GFileNo$ext"); } #------------------------------ =item output_prefix [PREFIX] I<Instance method.> Get the short string that all filenames for extracted body-parts will begin with (assuming that there is no better "recommended filename"). The default is F<"msg">. If PREFIX I<is not> given, the current output prefix is returned. If PREFIX I<is> given, the output prefix is set to the new value, and the previous value is returned. Used by L<output_filename()|/output_filename>. B<Note:> subclasses of MIME::Parser::Filer which override output_path() or output_filename() might not honor this setting; note, however, that the built-in subclasses honor it. =cut sub output_prefix { my ($self, $prefix) = @_; $self->{MPF_Prefix} = $prefix if (@_ > 1); $self->{MPF_Prefix}; } #------------------------------ =item output_type_ext I<Instance method.> Return a reference to the hash used by the default L<output_filename()|/output_filename> for mapping from content-types to extensions when there is no default extension to use. $emap = $filer->output_typemap; $emap->{'text/plain'} = '.txt'; $emap->{'text/html'} = '.html'; $emap->{'text/*'} = '.txt'; $emap->{'*/*'} = '.dat'; B<Note:> subclasses of MIME::Parser::Filer which override output_path() or output_filename() might not consult this hash; note, however, that the built-in subclasses consult it. =cut sub output_type_ext { my $self = shift; return $self->{MPF_Ext}; } #------------------------------ =item output_path HEAD I<Instance method, subclasses only.> Given a MIME head for a file to be extracted, come up with a good output pathname for the extracted file. This is the only method you need to worry about if you are building a custom filer. The default implementation does a lot of work; subclass implementers I<really> should try to just override its components instead of the whole thing. It works basically as follows: $directory = $self->output_dir($head); $filename = $head->recommended_filename(); if (!$filename or $self->ignore_filename() or $self->evil_filename($filename)) { $filename = $self->output_filename($head); } return $self->find_unused_path($directory, $filename); B<Note:> There are many, many, many ways you might want to control the naming of files, based on your application. If you don't like the behavior of this function, you can easily define your own subclass of MIME::Parser::Filer and override it there. B<Note:> Nickolay Saukh pointed out that, given the subjective nature of what is "evil", this function really shouldn't I<warn> about an evil filename, but maybe just issue a I<debug> message. I considered that, but then I thought: if debugging were off, people wouldn't know why (or even if) a given filename had been ignored. In mail robots that depend on externally-provided filenames, this could cause hard-to-diagnose problems. So, the message is still a warning. I<Thanks to Laurent Amon for pointing out problems with the original implementation, and for making some good suggestions. Thanks also to Achim Bohnet for pointing out that there should be a hookless, OO way of overriding the output path.> =cut sub output_path { my ($self, $head) = @_; ### Get the output directory: my $dir = $self->output_dir($head); ### Get the output filename as UTF-8 my $fname = $head->recommended_filename; ### Can we use it: if (!defined($fname)) { $self->debug("no filename recommended: synthesizing our own"); $fname = $self->output_filename($head); } elsif ($self->ignore_filename) { $self->debug("ignoring all external filenames: synthesizing our own"); $fname = $self->output_filename($head); } elsif ($self->evil_filename($fname)) { ### Can we save it by just taking the last element? my $ex = $self->exorcise_filename($fname); if (defined($ex) and !$self->evil_filename($ex)) { $self->whine("Provided filename '$fname' is regarded as evil, ", "but I was able to exorcise it and get something ", "usable."); $fname = $ex; } else { $self->whine("Provided filename '$fname' is regarded as evil; ", "I'm ignoring it and supplying my own."); $fname = $self->output_filename($head); } } else { # Untaint $fname... we know it's not evil if ($fname =~ /^(.*)$/) { $fname = $1; } } $self->debug("planning to use '$fname'"); ### Resolve collisions and return final path: return $self->find_unused_path($dir, $fname); } #------------------------------ =item purge I<Instance method, final.> Purge all files/directories created by the last parse. This method simply goes through the purgeable list in reverse order (see L</purgeable>) and removes all existing files/directories in it. You should not need to override this method. =cut sub purge { my ($self) = @_; foreach my $path (reverse @{$self->{MPF_Purgeable}}) { (-e $path) or next; ### must check: might delete DIR before DIR/FILE rmtree($path, 0, 1); (-e $path) and $self->whine("unable to purge: $path"); } 1; } #------------------------------ =item purgeable [FILE] I<Instance method, final.> Add FILE to the list of "purgeable" files/directories (those which will be removed if you do a C<purge()>). You should not need to override this method. If FILE is not given, the "purgeable" list is returned. This may be used for more-sophisticated purging. As a special case, invoking this method with a FILE that is an arrayref will replace the purgeable list with a copy of the array's contents, so [] may be used to clear the list. Note that the "purgeable" list is cleared when a parser begins a new parse; therefore, if you want to use purge() to do cleanup, you I<must> do so I<before> starting a new parse! =cut sub purgeable { my ($self, $path) = @_; return @{$self->{MPF_Purgeable}} if (@_ == 1); if (ref($path)) { $self->{MPF_Purgeable} = [ @$path ]; } else { push @{$self->{MPF_Purgeable}}, $path; } 1; } =back =cut #------------------------------------------------------------ #------------------------------------------------------------ =head2 MIME::Parser::FileInto This concrete subclass of MIME::Parser::Filer supports filing into a given directory. =over 4 =cut package MIME::Parser::FileInto; use strict; use vars qw(@ISA); @ISA = qw(MIME::Parser::Filer); #------------------------------ =item init DIRECTORY I<Instance method, initiallizer.> Set the directory where all files will go. =cut sub init { my ($self, $dir) = @_; $self->{MPFI_Dir} = $self->cleanup_dir($dir); } #------------------------------ # # output_dir HEAD # # I<Instance method, concrete override.> # Return the output directory where the files go. # sub output_dir { shift->{MPFI_Dir}; } =back =cut #------------------------------------------------------------ #------------------------------------------------------------ =head2 MIME::Parser::FileUnder This concrete subclass of MIME::Parser::Filer supports filing under a given directory, using one subdirectory per message, but with all message parts in the same directory. =over 4 =cut package MIME::Parser::FileUnder; use strict; use vars qw(@ISA); @ISA = qw(MIME::Parser::Filer); #------------------------------ =item init BASEDIR, OPTSHASH... I<Instance method, initiallizer.> Set the base directory which will contain the message directories. If used, then each parse of begins by creating a new subdirectory of BASEDIR where the actual parts of the message are placed. OPTSHASH can contain the following: =over 4 =item DirName Explicitly set the name of the subdirectory which is created. The default is to use the time, process id, and a sequence number, but you might want a predictable directory. =item Purge Automatically purge the contents of the directory (including all subdirectories) before each parse. This is really only needed if using an explicit DirName, and is provided as a convenience only. Currently we use the 1-arg form of File::Path::rmtree; you should familiarize yourself with the caveats therein. =back The output_dir() will return the path to this message-specific directory until the next parse is begun, so you can do this: use File::Path; $parser->output_under("/tmp"); $ent = eval { $parser->parse_open($msg); }; ### parse if (!$ent) { ### parse failed rmtree($parser->output_dir); die "parse failed: $@"; } else { ### parse succeeded ...do stuff... } =cut sub init { my ($self, $basedir, %opts) = @_; $self->{MPFU_Base} = $self->cleanup_dir($basedir); $self->{MPFU_DirName} = $opts{DirName}; $self->{MPFU_Purge} = $opts{Purge}; } #------------------------------ # # init_parse # # I<Instance method, override.> # Prepare to start parsing a new message. # sub init_parse { my $self = shift; ### Invoke inherited method first! $self->SUPER::init_parse; ### Determine the subdirectory of their base to use: my $subdir = (defined($self->{MPFU_DirName}) ? $self->{MPFU_DirName} : ("msg-" . scalar(time) . "-" . MIME::Parser::Filer::untainted_pid() . "-" . $GSubdirNo++)); $self->debug("subdir = $subdir"); ### Determine full path to the per-message output directory: $self->{MPFU_Dir} = File::Spec->catfile($self->{MPFU_Base}, $subdir); ### Remove and re-create the per-message output directory: rmtree $self->output_dir if $self->{MPFU_Purge}; (-d $self->output_dir) or mkdir $self->output_dir, 0700 or die "mkdir ".$self->output_dir.": $!\n"; ### Add the per-message output directory to the puregables: $self->purgeable($self->output_dir); 1; } #------------------------------ # # output_dir HEAD # # I<Instance method, concrete override.> # Return the output directory that we used for the last parse. # sub output_dir { shift->{MPFU_Dir}; } =back =cut 1; __END__ =head1 SEE ALSO L<MIME::Tools>, L<MIME::Parser> =head1 AUTHOR Eryq (F<eryq@zeegee.com>), ZeeGee Software Inc (F<http://www.zeegee.com>). All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.