--- /dev/null
+package PerlIO::via::File::KDBX::HmacBlock;
+# ABSTRACT: HMAC block-stream PerlIO layer
+
+use warnings;
+use strict;
+
+use Crypt::Digest qw(digest_data);
+use Crypt::Mac::HMAC qw(hmac);
+use File::KDBX::Error;
+use File::KDBX::Util qw(:io assert_64bit);
+use namespace::clean;
+
+our $VERSION = '999.999'; # VERSION
+our $BLOCK_SIZE = 1048576;
+our $ERROR;
+
+=method push
+
+ PerlIO::via::File::KDBX::HmacBlock->push($fh, key => $key);
+ PerlIO::via::File::KDBX::HmacBlock->push($fh, key => $key, block_size => $size);
+
+Push a new HMAC-block layer with arguments. A key is required.
+
+B<WARNING:> You mustn't push this layer using C<binmode> directly because the layer needs to be initialized
+with the key and any other desired attributes.
+
+B<WARNING:> When writing, you mustn't close the filehandle before popping this layer (using
+C<binmode($fh, ':pop')>) or the stream will be truncated. The layer needs to know when there is no more data
+before the filehandle closes so it can write the final block (which will likely be shorter than the other
+blocks), and the way to indicate that is by popping the layer.
+
+=cut
+
+my %PUSHED_ARGS;
+sub push {
+ assert_64bit;
+
+ %PUSHED_ARGS and throw 'Pushing HmacBlock layer would stomp existing arguments';
+
+ my $class = shift;
+ my $fh = shift;
+ my %args = @_ % 2 == 0 ? @_ : (key => @_);
+ $args{key} or throw 'Must pass a key';
+
+ my $key_size = length($args{key});
+ $key_size == 64 or throw 'Key must be 64 bytes in length', size => $key_size;
+
+ %PUSHED_ARGS = %args;
+ binmode($fh, ':via(' . __PACKAGE__ . ')');
+}
+
+sub PUSHED {
+ my ($class, $mode) = @_;
+
+ %PUSHED_ARGS or throw 'Programmer error: Use PerlIO::via::File::KDBX::HmacBlock->push instead of binmode';
+
+ $ENV{DEBUG_STREAM} and print STDERR "PUSHED\t$class\n";
+ my $buf = '';
+ my $self = bless {
+ block_index => 0,
+ block_size => $PUSHED_ARGS{block_size} || $BLOCK_SIZE,
+ buffer => \$buf,
+ key => $PUSHED_ARGS{key},
+ mode => $mode,
+ }, $class;
+ %PUSHED_ARGS = ();
+ return $self;
+}
+
+sub FILL {
+ my ($self, $fh) = @_;
+
+ $ENV{DEBUG_STREAM} and print STDERR "FILL\t$self\n";
+ return if $self->EOF($fh);
+
+ my $block = eval { $self->_read_hashed_block($fh) };
+ if (my $err = $@) {
+ $self->_set_error($err);
+ return;
+ }
+ if (length($block) == 0) {
+ $self->{eof} = 1;
+ return;
+ }
+ return $block;
+}
+
+sub WRITE {
+ my ($self, $buf, $fh) = @_;
+
+ $ENV{DEBUG_STREAM} and print STDERR "WRITE\t$self\n";
+ return 0 if $self->EOF($fh);
+
+ ${$self->{buffer}} .= $buf;
+
+ $self->FLUSH($fh);
+
+ return length($buf);
+}
+
+sub POPPED {
+ my ($self, $fh) = @_;
+
+ $ENV{DEBUG_STREAM} and print STDERR "POPPED\t$self\n";
+ return if $self->mode !~ /^w/;
+
+ $self->FLUSH($fh);
+ eval {
+ $self->_write_next_hmac_block($fh); # partial block with remaining content
+ $self->_write_final_hmac_block($fh); # terminating block
+ };
+ $self->_set_error($@) if $@;
+}
+
+sub FLUSH {
+ my ($self, $fh) = @_;
+
+ $ENV{DEBUG_STREAM} and print STDERR "FLUSH\t$self\n";
+ return 0 if !ref $self;
+
+ eval {
+ while ($self->block_size <= length(${$self->{buffer}})) {
+ $self->_write_next_hmac_block($fh);
+ }
+ };
+ if (my $err = $@) {
+ $self->_set_error($err);
+ return -1;
+ }
+
+ return 0;
+}
+
+sub EOF {
+ $ENV{DEBUG_STREAM} and print STDERR "EOF\t$_[0]\n";
+ $_[0]->{eof} || $_[0]->ERROR($_[1]);
+}
+sub ERROR {
+ $ENV{DEBUG_STREAM} and print STDERR "ERROR\t$_[0] : ", $_[0]->{error} // 'ok', "\n";
+ $ERROR = $_[0]->{error} if $_[0]->{error};
+ $_[0]->{error} ? 1 : 0;
+}
+sub CLEARERR {
+ $ENV{DEBUG_STREAM} and print STDERR "CLEARERR\t$_[0]\n";
+ # delete $_[0]->{error};
+}
+
+=attr key
+
+ $key = $hmac_block->key;
+
+Get the key used for authentication. The key must be exactly 64 bytes in size.
+
+=cut
+
+sub key { $_[0]->{key} or throw 'Key is not set' }
+
+=attr block_size
+
+ $size = $hmac_block->block_size;
+
+Get the block size. Default is C<$PerlIO::via::File::KDBX::HmacBlock::BLOCK_SIZE>.
+
+This only matters in write mode. When reading, block size is detected from the stream.
+
+=cut
+
+sub block_size { $_[0]->{block_size} ||= $BLOCK_SIZE }
+
+=attr block_index
+
+=attr buffer
+
+=attr mode
+
+Internal attributes.
+
+=cut
+
+sub block_index { $_[0]->{block_index} ||= 0 }
+sub buffer { $_[0]->{buffer} }
+sub mode { $_[0]->{mode} }
+
+sub _read_hashed_block {
+ my $self = shift;
+ my $fh = shift;
+
+ read_all $fh, my $hmac, 32 or throw 'Failed to read HMAC';
+
+ read_all $fh, my $size_buf, 4 or throw 'Failed to read HMAC block size';
+ my ($size) = unpack('L<', $size_buf);
+
+ my $block = '';
+ if (0 < $size) {
+ read_all $fh, $block, $size
+ or throw 'Failed to read HMAC block', index => $self->block_index, size => $size;
+ }
+
+ my $index_buf = pack('Q<', $self->block_index);
+ my $got_hmac = hmac('SHA256', $self->_hmac_key,
+ $index_buf,
+ $size_buf,
+ $block,
+ );
+
+ $hmac eq $got_hmac
+ or throw 'Block authentication failed', index => $self->block_index, got => $got_hmac, expected => $hmac;
+
+ $self->{block_index}++;
+
+ return $block;
+}
+
+sub _write_next_hmac_block {
+ my $self = shift;
+ my $fh = shift;
+ my $buffer = shift // $self->buffer;
+ my $allow_empty = shift;
+
+ my $size = length($$buffer);
+ $size = $self->block_size if $self->block_size < $size;
+ return 0 if $size == 0 && !$allow_empty;
+
+ my $block = '';
+ $block = substr($$buffer, 0, $size, '') if 0 < $size;
+
+ my $index_buf = pack('Q<', $self->block_index);
+ my $size_buf = pack('L<', $size);
+ my $hmac = hmac('SHA256', $self->_hmac_key,
+ $index_buf,
+ $size_buf,
+ $block,
+ );
+
+ print $fh $hmac, $size_buf, $block
+ or throw 'Failed to write HMAC block', hmac => $hmac, block_size => $size, err => $fh->error;
+
+ $self->{block_index}++;
+ return 0;
+}
+
+sub _write_final_hmac_block {
+ my $self = shift;
+ my $fh = shift;
+
+ $self->_write_next_hmac_block($fh, \'', 1);
+}
+
+sub _hmac_key {
+ my $self = shift;
+ my $key = shift // $self->key;
+ my $index = shift // $self->block_index;
+
+ my $index_buf = pack('Q<', $index);
+ my $hmac_key = digest_data('SHA512', $index_buf, $key);
+ return $hmac_key;
+}
+
+sub _set_error {
+ my $self = shift;
+ $ENV{DEBUG_STREAM} and print STDERR "err\t$self\n";
+ if (exists &Errno::EPROTO) {
+ $! = &Errno::EPROTO;
+ }
+ elsif (exists &Errno::EIO) {
+ $! = &Errno::EIO;
+ }
+ $self->{error} = $ERROR = File::KDBX::Error->new(@_);
+}
+
+1;
+__END__
+
+=head1 DESCRIPTION
+
+Writing to a handle with this layer will transform the data in a series of blocks. An HMAC is calculated for
+each block and is included in the output.
+
+Reading from a handle, each block will be verified and authenticated as the blocks are disassembled back into
+a data stream.
+
+Each block is encoded thusly:
+
+=for :list
+* HMAC - 32 bytes, calculated over [block index (increments starting with 0), block size and data]
+* Block size - Little-endian unsigned 32-bit (counting only the data)
+* Data - String of bytes
+
+The terminating block is an empty block encoded as usual but block size is 0 and there is no data.
+
+=cut
projects / chaz / p5-File-KDBX / blobdiff