[pve-devel] [PATCH v2 http-server 2/2] AnyEvent: Fix #3990 - make small files uploadable

Matthias Heiserer m.heiserer at proxmox.com
Fri May 13 15:49:00 CEST 2022


== The problem
Upload of files smaller than ~16kb failed.
This was because the code assumed that it would be called
several times, and each time would do a certain action.
When the whole file was in the buffer, this failed because
the function would try parssing the first part in the payload and
then return, instead of parsing the rest of the available data.

== Why not just modifying the current code a bit?
The code had a lot of nested control statements and a
non-intuitive control flow (phase 0->2->1->1->1 and so on).

The way the phases and buffer content were checked made it
rather difficult to just fix a few lines.

== What was changed
* Part headers are parsed with a single regex line each,
 which improves code readability.

* Parsing the content is done in order, so even if the whole data is in the buffer,
 it can be read in one go. Files of arbitrary sizes can be uploaded.

== Tested with
* Uploaded 0B, 1B, 14KB, 16KB, 1GB, 10GB, 20GB files

* Tested with all checksums and without

* Tested on firefox, chromium, and pvesh

I didn't do any fuzzing or automated upload testing.

== Drawbacks & Potential issues
* Part headers are hardcoded, adding new ones requries modifying this file

== does not fix
* upload can still time out

Signed-off-by: Matthias Heiserer <m.heiserer at proxmox.com>
---

Note:
Regarding trim, I forgot to answer the mail.
Trim is imo a good name, as several languagues (e.g. rust, javascript)
use trim to mean mean "remove all whitespace, including newlines and such".
I can send a v3 if that's a problem.

Changes from v1:
* fix whitespace in separate patch
* move trim into inline closure
* correctly call trim
* replace [^\S] with \S in regexes
* improve trim regex: don't replace string
* check for phase 1 once
* remove regex comment

 src/PVE/APIServer/AnyEvent.pm | 146 ++++++++++++++++++----------------
 1 file changed, 76 insertions(+), 70 deletions(-)

diff --git a/src/PVE/APIServer/AnyEvent.pm b/src/PVE/APIServer/AnyEvent.pm
index b8bc35d..1c07d96 100644
--- a/src/PVE/APIServer/AnyEvent.pm
+++ b/src/PVE/APIServer/AnyEvent.pm
@@ -1158,62 +1158,81 @@ sub handle_request {
 sub file_upload_multipart {
     my ($self, $reqstate, $auth, $method, $path, $rstate) = @_;
 
+    my $trim = sub {
+	my ($string) = @_;
+	$_[0] =~ /\s*(\S+)/;
+	return $1;
+    };
+
     eval {
 	my $boundary = $rstate->{boundary};
 	my $hdl = $reqstate->{hdl};
 	my $startlen = length($hdl->{rbuf});
 
-	if ($rstate->{phase} == 0) { # skip everything until start
-	    if ($hdl->{rbuf} =~ s/^.*?--\Q$boundary\E  \015?\012
-                       ((?:[^\015]+\015\012)* ) \015?\012//xs) {
-		my $header = $1;
-		my ($ct, $disp, $name, $filename);
-		foreach my $line (split(/\015?\012/, $header)) {
-		    # assume we have single line headers
-		    if ($line =~ m/^Content-Type\s*:\s*(.*)/i) {
-			$ct = parse_content_type($1);
-		    } elsif ($line =~ m/^Content-Disposition\s*:\s*(.*)/i) {
-			($disp, $name, $filename) = parse_content_disposition($1);
-		    }
-		}
+	my $newline = qr/\015?\012/;
+	my $delimiter = qr/--\Q$boundary\E${newline}/;
+	my $closeDelimiter = qr/--\Q$boundary\E--${newline}/;
 
-		if (!($disp && $disp eq 'form-data' && $name)) {
-		    syslog('err', "wrong content disposition in multipart - abort upload");
-		    $rstate->{phase} = -1;
-		} else {
+	my $check_disposition = sub {
+	    my ($disp) = @_;
+	    die "wrong Content-Disposition in multipart, expected `form-data` - abort upload"
+		if $disp ne 'form-data';
+	};
 
-		    $rstate->{fieldname} = $name;
+	# Phase 0 - preserve boundary, but remove everything before
+	if ($rstate->{phase} == 0 && $hdl->{rbuf} =~ s/^.*?($delimiter)/$1/xs) {
+	    $rstate->{read} += $startlen - length($hdl->{rbuf});
+	    $rstate->{phase} = 1;
+	}
 
-		    if ($filename) {
-			if ($name eq 'filename') {
-			    # found file upload data
-			    $rstate->{phase} = 1;
-			    $rstate->{filename} = $filename;
-			} else {
-			    syslog('err', "wrong field name for file upload - abort upload");
-			    $rstate->{phase} = -1;
-			}
-		    } else {
-			# found form data for field $name
-			$rstate->{phase} = 2;
-		    }
-		}
-	    } else {
-		my $len = length($hdl->{rbuf});
-		substr($hdl->{rbuf}, 0, $len - $rstate->{maxheader}, '')
-		    if $len > $rstate->{maxheader}; # skip garbage
+	# Phase 1 - parse payload without file data
+	if ($rstate->{phase} == 1) {
+	    if ($hdl->{rbuf} =~
+		s/^${delimiter}Content-Disposition: (.*?); name="content"(.*?)($delimiter)/$3/s
+	    ) {
+		$check_disposition->($1);
+		$rstate->{params}->{content} = $trim->($2);
 	    }
-	} elsif ($rstate->{phase} == 1) { # inside file - dump until end marker
-	    if ($hdl->{rbuf} =~ s/^(.*?)\015?\012(--\Q$boundary\E(--)? \015?\012(.*))$/$2/xs) {
+
+	    if ( $hdl->{rbuf} =~
+		s/^${delimiter}Content-Disposition: (.*?); name="checksum-algorithm"(.*?)($delimiter)/$3/s
+	    ) {
+		$check_disposition->($1);
+		$rstate->{params}->{"checksum-algorithm"} = $trim->($2);
+	    }
+
+	    if ( $hdl->{rbuf} =~
+		s/^${delimiter}Content-Disposition: (.*?); name="checksum"(.*?)($delimiter)/$3/s
+	    ) {
+		$check_disposition->($1);
+		$rstate->{params}->{checksum} = $trim->($2);
+	    }
+
+	    if ( $hdl->{rbuf} =~
+		s/^${delimiter}
+		Content-Disposition:\ (.*?);\ name="(.*?)";\ filename="([^"]+)"${newline}
+		Content-Type:\ \S*\s+
+		//sxx
+	    ) {
+		$check_disposition->($1);
+		die "wrong field `name` for file upload, expected `filename` - abort upload"
+		    if $2 ne "filename";
+		$rstate->{phase} = 2;
+		$rstate->{params}->{filename} = $trim->($3);
+	    }
+	}
+
+	# Phase 2 - dump content into file
+	if ($rstate->{phase} == 2) {
+	    if ($hdl->{rbuf} =~ s/^(.*?)${newline}?+${closeDelimiter}.*$//s) {
 		my ($rest, $eof) = ($1, $3);
 		my $len = length($rest);
 		die "write to temporary file failed - $!"
 		    if syswrite($rstate->{outfh}, $rest) != $len;
 		$rstate->{ctx}->add($rest);
-		$rstate->{params}->{filename} = $rstate->{filename};
 		$rstate->{md5sum} = $rstate->{ctx}->hexdigest;
 		$rstate->{bytes} += $len;
-		$rstate->{phase} =  $eof ? 100 : 0;
+		$rstate->{phase} =  100;
 	    } else {
 		my $len = length($hdl->{rbuf});
 		my $wlen = $len - $rstate->{boundlen};
@@ -1225,42 +1244,29 @@ sub file_upload_multipart {
 		    $rstate->{ctx}->add($data);
 		}
 	    }
-	} elsif ($rstate->{phase} == 2) { # inside normal field
+	}
 
-	    if ($hdl->{rbuf} =~ s/^(.*?)\015?\012(--\Q$boundary\E(--)? \015?\012(.*))$/$2/xs) {
-		my ($rest, $eof) = ($1, $3);
-		my $len = length($rest);
-		$rstate->{post_size} += $len;
-		if ($rstate->{post_size} < $limit_max_post) {
-		    $rstate->{params}->{$rstate->{fieldname}} = $rest;
-		    $rstate->{phase} = $eof ? 100 : 0;
-		} else {
-		    syslog('err', "form data to large - abort upload");
-		    $rstate->{phase} = -1; # skip
-		}
-	    }
-	} else { # skip
-	    my $len = length($hdl->{rbuf});
-	    substr($hdl->{rbuf}, 0, $len, ''); # empty rbuf
+	# Phase 100 - transfer finished
+	if ($rstate->{phase} == 100) {
+	    my $elapsed = tv_interval($rstate->{starttime});
+
+	    my $rate = int($rstate->{bytes} / ($elapsed * 1024 * 1024));
+	    syslog('info',
+		"multipart upload complete (size: %d time: %ds rate: %.2fMiB/s md5sum: %s)",
+		$rstate->{bytes}, $elapsed, $rate, $rstate->{md5sum}
+	    );
+	    $self->handle_api2_request($reqstate, $auth, $method, $path, $rstate);
 	}
 
 	$rstate->{read} += $startlen - length($hdl->{rbuf});
 
-	if (!$rstate->{done} && ($rstate->{read} + length($hdl->{rbuf})) >= $rstate->{size}) {
-	    $rstate->{done} = 1; # make sure we dont get called twice
-	    if ($rstate->{phase} < 0 || !$rstate->{md5sum}) {
-		die "upload failed\n";
-	    } else {
-		my $elapsed = tv_interval($rstate->{starttime});
-
-		my $rate = int($rstate->{bytes} / ($elapsed * 1024 * 1024));
-		syslog('info',
-		    "multipart upload complete (size: %d time: %ds rate: %.2fMiB/s md5sum: %s)",
-		     $rstate->{bytes}, $elapsed, $rate, $rstate->{md5sum}
-		);
-		$self->handle_api2_request($reqstate, $auth, $method, $path, $rstate);
-	    }
+	if (
+	    $rstate->{read} + length($hdl->{rbuf}) >= $rstate->{size}
+	    && $rstate->{phase} != 100
+	) {
+	    die "upload failed";
 	}
+
     };
     if (my $err = $@) {
 	syslog('err', $err);
-- 
2.30.2





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