Workshop o mikrokontrolérech na SKSP 2024.
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# Poor Man's CGI Module for Perl
#
# (c) 2002--2017 Martin Mares <mj@ucw.cz>
# Slightly modified by Tomas Valla <tom@ucw.cz>
#
# This software may be freely distributed and used according to the terms
# of the GNU Lesser General Public License.
package UCW::CGI;
use strict;
use warnings;
require Exporter;
our $VERSION = 1.0;
our @ISA = qw(Exporter);
our @EXPORT = qw(&html_escape &url_escape &url_deescape &url_param_escape &url_param_deescape &self_ref &self_form &http_get);
our @EXPORT_OK = qw();
# Configuration settings
our $debug = 0;
our $utf8_mode = 0;
sub http_error($;@) {
my $err = shift @_;
print join("\n", "Status: $err", "Content-Type: text/plain", @_, "", $err, "");
exit;
}
### Escaping ###
sub url_escape($) {
my $x = shift @_;
defined $x or return;
utf8::encode($x) if $utf8_mode;
$x =~ s/([^-\$_.!*'(),0-9A-Za-z\x80-\xff])/"%".unpack('H2',$1)/ge;
utf8::decode($x) if $utf8_mode;
return $x;
}
sub url_strict_escape($) {
my $x = shift @_;
defined $x or return;
utf8::encode($x);
$x =~ s/([^-\$_.!*'(),0-9A-Za-z])/"%".unpack('H2',$1)/ge;
return $x;
}
sub url_deescape($) {
my $x = shift @_;
defined $x or return;
utf8::encode($x) if $utf8_mode;
$x =~ s/%(..)/pack("H2",$1)/ge;
utf8::decode($x) if $utf8_mode;
return $x;
}
sub url_param_escape($) {
my $x = shift @_;
defined $x or return;
utf8::encode($x) if $utf8_mode;
$x =~ s/([^-\$_.!*'(),0-9A-Za-z])/"%".unpack('H2',$1)/ge;
$x =~ s/%20/+/g;
utf8::decode($x) if $utf8_mode;
return $x;
}
sub url_param_deescape($) {
my $x = shift @_;
defined $x or return;
$x =~ s/\+/ /g;
return url_deescape($x);
}
sub html_escape($) {
my $x = shift @_;
defined $x or return;
$x =~ s/&/&amp;/g;
$x =~ s/</&lt;/g;
$x =~ s/>/&gt;/g;
$x =~ s/"/&quot;/g;
$x =~ s/'/&#39;/g;
return $x;
}
### Analysing RFC 822 Style Headers ###
sub rfc822_prepare($) {
my $x = shift @_;
# Convert all %'s and backslash escapes to %xx escapes
$x =~ s/%/%25/g;
$x =~ s/\\(.)/"%".unpack("H2",$1)/ge;
# Remove all comments, beware, they can be nested (unterminated comments are closed at EOL automatically)
while ($x =~ s/^(("[^"]*"|[^"(])*(\([^)]*)*)(\([^()]*(\)|$))/$1 /) { }
# Remove quotes and escape dangerous characters inside (again closing at the end automatically)
$x =~ s{"([^"]*)("|$)}{my $z=$1; $z =~ s/([^0-9a-zA-Z%_-])/"%".unpack("H2",$1)/ge; $z;}ge;
# All control characters are properly escaped, tokens are clearly visible.
# Finally remove all unnecessary spaces.
$x =~ s/\s+/ /g;
$x =~ s/(^ | $)//g;
$x =~ s{\s*([()<>@,;:\\"/\[\]?=])\s*}{$1}g;
return $x;
}
sub rfc822_deescape($) {
my $x = shift @_;
return url_deescape($x);
}
### Reading of HTTP headers ###
sub http_get($) {
my $h = shift @_;
$h =~ tr/a-z-/A-Z_/;
return $ENV{"HTTP_$h"} // $ENV{"$h"};
}
### Parsing of Arguments ###
my $main_arg_table;
my %raw_args;
sub parse_raw_args_ll($$) {
my ($arg, $s) = @_;
$s =~ s/\r\n/\n/g;
$s =~ s/\r/\n/g;
utf8::decode($s) if $utf8_mode;
push @{$raw_args{$arg}}, $s;
}
sub parse_raw_args($) {
my ($s) = @_;
$s =~ s/\s+//;
for $_ (split /[&:]/, $s) {
(/^([^=]+)=(.*)$/) or next;
my $arg = $1;
$_ = $2;
s/\+/ /g;
s/%(..)/pack("H2",$1)/eg;
parse_raw_args_ll($arg, $_);
}
}
sub parse_multipart_form_data();
sub init_args() {
if (!defined $ENV{"GATEWAY_INTERFACE"}) {
print STDERR "Must be called as a CGI script.\n";
$UCW::CGI::ErrorHandler::exit_code = 1;
exit;
}
my $method = $ENV{"REQUEST_METHOD"};
if (my $qs = $ENV{"QUERY_STRING"}) {
parse_raw_args($qs);
}
if ($method eq "GET" || $method eq "HEAD") {
} elsif ($method eq "POST") {
my $content_type = $ENV{"CONTENT_TYPE"} // "";
if ($content_type =~ /^application\/x-www-form-urlencoded\b/i) {
while (<STDIN>) {
chomp;
parse_raw_args($_);
}
} elsif ($content_type =~ /^multipart\/form-data\b/i) {
parse_multipart_form_data();
} else {
http_error "415 Unsupported Media Type";
exit;
}
} else {
http_error "405 Method Not Allowed", "Allow: GET, HEAD, POST";
}
}
sub parse_args($) { # CAVEAT: attached files must be defined in the main arg table
my $args = shift @_;
if (!$main_arg_table) {
$main_arg_table = $args;
init_args();
}
for my $a (values %$args) {
my $r = ref($a->{'var'});
$a->{'default'} //= '';
if ($r eq 'SCALAR') {
${$a->{'var'}} = $a->{'default'};
} elsif ($r eq 'ARRAY') {
@{$a->{'var'}} = ();
}
}
for my $arg (keys %$args) {
my $a = $args->{$arg};
defined($raw_args{$arg}) or next;
for (@{$raw_args{$arg}}) {
$a->{'multiline'} or s/(\n|\t)/ /g;
unless ($a->{'preserve_spaces'}) {
s/^\s+//;
s/\s+$//;
}
if (my $rx = $a->{'check'}) {
if (!/^$rx$/) { $_ = $a->{'default'}; }
}
my $v = $a->{'var'};
my $r = ref($v);
if ($r eq 'SCALAR') {
$$v = $_;
} elsif ($r eq 'ARRAY') {
push @$v, $_;
}
}
}
}
### Parsing Multipart Form Data ###
my $boundary;
my $boundary_len;
my $mp_buffer;
my $mp_buffer_i;
my $mp_buffer_boundary;
my $mp_eof;
sub refill_mp_data($) {
my ($more) = @_;
if ($mp_buffer_boundary >= $mp_buffer_i) {
return $mp_buffer_boundary - $mp_buffer_i;
} elsif ($mp_buffer_i + $more <= length($mp_buffer) - $boundary_len) {
return $more;
} else {
if ($mp_buffer_i) {
$mp_buffer = substr($mp_buffer, $mp_buffer_i);
$mp_buffer_i = 0;
}
while ($mp_buffer_i + $more > length($mp_buffer) - $boundary_len) {
last if $mp_eof;
my $data;
my $n = read(STDIN, $data, 2048);
if ($n > 0) {
$mp_buffer .= $data;
} else {
$mp_eof = 1;
}
}
$mp_buffer_boundary = index($mp_buffer, $boundary, $mp_buffer_i);
if ($mp_buffer_boundary >= 0) {
return $mp_buffer_boundary;
} elsif ($mp_eof) {
return length($mp_buffer);
} else {
return length($mp_buffer) - $boundary_len;
}
}
}
sub get_mp_line($) {
my ($allow_empty) = @_;
my $n = refill_mp_data(1024);
my $i = index($mp_buffer, "\r\n", $mp_buffer_i);
if ($i >= $mp_buffer_i && $i < $mp_buffer_i + $n - 1) {
my $s = substr($mp_buffer, $mp_buffer_i, $i - $mp_buffer_i);
$mp_buffer_i = $i + 2;
return $s;
} elsif ($allow_empty) {
if ($n) { # An incomplete line
my $s = substr($mp_buffer, $mp_buffer_i, $n);
$mp_buffer_i += $n;
return $s;
} else { # No more lines
return undef;
}
} else {
http_error "400 Bad Request: Premature end of multipart POST data";
}
}
sub skip_mp_boundary() {
if ($mp_buffer_boundary != $mp_buffer_i) {
http_error "400 Bad Request: Premature end of multipart POST data";
}
$mp_buffer_boundary = -1;
$mp_buffer_i += 2;
my $b = get_mp_line(0);
print STDERR "SEP $b\n" if $debug;
$mp_buffer_boundary = index($mp_buffer, $boundary, $mp_buffer_i);
if (substr("\r\n$b", 0, $boundary_len) eq "$boundary--") {
return 0;
} else {
return 1;
}
}
sub parse_mp_header() {
my $h = {};
my $last;
while ((my $l = get_mp_line(0)) ne "") {
print STDERR "HH $l\n" if $debug;
if (my ($name, $value) = ($l =~ /([A-Za-z0-9-]+)\s*:\s*(.*)/)) {
$name =~ tr/A-Z/a-z/;
$h->{$name} = $value;
$last = $name;
} elsif ($l =~ /^\s+/ && $last) {
$h->{$last} .= $l;
} else {
$last = undef;
}
}
foreach my $n (keys %$h) {
$h->{$n} = rfc822_prepare($h->{$n});
print STDERR "H $n: $h->{$n}\n" if $debug;
}
return (keys %$h) ? $h : undef;
}
sub parse_multipart_form_data() {
# First of all, find the boundary string
my $ct = rfc822_prepare($ENV{"CONTENT_TYPE"});
if (!(($boundary) = ($ct =~ /^.*;\s*boundary=([^; ]+)/))) {
http_error "400 Bad Request: Multipart content with no boundary string received";
}
$boundary = rfc822_deescape($boundary);
print STDERR "BOUNDARY IS $boundary\n" if $debug;
# BUG: IE 3.01 on Macintosh forgets to add the "--" at the start of the boundary string
# as the MIME specs preach. Workaround borrowed from CGI.pm in Perl distribution.
my $agent = http_get("User-Agent") // "";
$boundary = "--$boundary" unless $agent =~ /MSIE\s+3\.0[12];\s*Mac/;
$boundary = "\r\n$boundary";
$boundary_len = length($boundary) + 2;
# Check upload size in advance
if (my $size = http_get("Content-Length")) {
my $max_allowed = 0;
foreach my $a (values %$main_arg_table) {
$max_allowed += $a->{"maxsize"} || 65536;
}
if ($size > $max_allowed) {
http_error "413 Request Entity Too Large";
}
}
# Initialize our buffering mechanism and part splitter
$mp_buffer = "\r\n";
$mp_buffer_i = 0;
$mp_buffer_boundary = -1;
$mp_eof = 0;
# Skip garbage before the 1st part
while (my $i = refill_mp_data(256)) { $mp_buffer_i += $i; }
skip_mp_boundary() || return;
# Process individual parts
do { PART: {
print STDERR "NEXT PART\n" if $debug;
my $h = parse_mp_header();
my ($field, $cdisp, $a);
if ($h &&
($cdisp = $h->{"content-disposition"}) &&
$cdisp =~ /^form-data/ &&
(($field) = ($cdisp =~ /;name=([^;]+)/)) &&
($a = $main_arg_table->{"$field"})) {
print STDERR "FIELD $field\n" if $debug;
if (defined $h->{"content-transfer-encoding"}) {
http_error "400 Bad Request: Unexpected Content-Transfer-Encoding";
}
if (defined $a->{"var"}) {
while (defined (my $l = get_mp_line(1))) {
print STDERR "VALUE $l\n" if $debug;
parse_raw_args_ll($field, $l);
}
next PART;
} elsif (defined $a->{"file"}) {
require File::Temp;
require IO::Handle;
my $max_size = $a->{"maxsize"} || 1048576;
my @tmpargs = (undef, UNLINK => 1);
push @tmpargs, DIR => $a->{"tmpdir"} if defined $a->{"tmpdir"};
my ($fh, $fn) = File::Temp::tempfile(@tmpargs);
print STDERR "FILE UPLOAD to $fn\n" if $debug;
${$a->{"file"}} = $fn;
${$a->{"fh"}} = $fh if defined $a->{"fh"};
if (defined $a->{"filename"}){
my ($filename) = ($cdisp =~ /;filename=([^;]+)/);
(${$a->{"filename"}}) = rfc822_deescape($filename) if defined $filename;
}
my $total_size = 0;
while (my $i = refill_mp_data(4096)) {
print $fh substr($mp_buffer, $mp_buffer_i, $i);
$mp_buffer_i += $i;
$total_size += $i;
if ($total_size > $max_size) { http_error "413 Request Entity Too Large"; }
}
$fh->flush(); # Don't close the handle, the file would disappear otherwise
next PART;
}
}
print STDERR "SKIPPING\n" if $debug;
while (my $i = refill_mp_data(256)) { $mp_buffer_i += $i; }
} } while (skip_mp_boundary());
}
### Generating Self-ref URL's ###
sub make_out_args(@) { # Usage: make_out_args([arg_table, ...] name => value, ...)
my @arg_tables = ( $main_arg_table );
while (@_ && ref($_[0]) eq 'HASH') {
push @arg_tables, shift @_;
}
my %overrides = @_;
my $out = {};
for my $table (@arg_tables) {
for my $name (keys %$table) {
my $arg = $table->{$name};
defined($arg->{'var'}) || next;
defined($arg->{'pass'}) && !$arg->{'pass'} && !exists $overrides{$name} && next;
defined $arg->{'default'} or $arg->{'default'} = "";
my $value;
if (!defined($value = $overrides{$name})) {
if (exists $overrides{$name}) {
$value = $arg->{'default'};
} else {
$value = ${$arg->{'var'}};
defined $value or $value = $arg->{'default'};
}
}
if ($value ne $arg->{'default'}) {
$out->{$name} = $value;
}
}
}
return $out;
}
sub self_ref(@) {
my $out = make_out_args(@_);
return "?" . join(':', map { "$_=" . url_param_escape($out->{$_}) } sort keys %$out);
}
sub self_form(@) {
my $out = make_out_args(@_);
return join('', map { "<input type=hidden name=$_ value='" . html_escape($out->{$_}) . "'>\n" } sort keys %$out);
}
### Cookies
sub set_cookie($$@) {
#
# Unfortunately, the support for the new cookie standard (RFC 2965) among
# web browsers is still very scarce, so we are still using the old Netscape
# specification.
#
# Usage: set_cookie(name, value, option => value...), where options are:
#
# max-age maximal age in seconds
# domain domain name scope
# path path name scope
# secure if present, cookie applies only to SSL connections
# (in this case, the value should be undefined)
# discard if present with any value, the cookie is discarded
#
my $key = shift @_;
my $value = shift @_;
my %other = @_;
if (exists $other{'discard'}) {
delete $other{'discard'};
$other{'max-age'} = 0;
}
if (defined(my $age = $other{'max-age'})) {
delete $other{'max-age'};
my $exp = ($age ? (time + $age) : 0);
# Avoid problems with locales
my ($S,$M,$H,$d,$m,$y,$wd) = gmtime $exp;
my @wdays = ( 'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat' );
my @mons = ( 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec' );
$other{'expires'} = sprintf("%s, %02d-%s-%d %02d:%02d:%02d GMT",
$wdays[$wd], $d, $mons[$m], $y+1900, $H, $M, $S);
}
print "Set-Cookie: $key=", url_strict_escape($value);
foreach my $k (keys %other) {
print "; $k";
print "=", $other{$k} if defined $other{$k};
}
print "\n";
}
sub parse_cookies() {
my $h = http_get("Cookie") or return ();
my @cook = ();
foreach my $x (split /;\s*/, $h) {
my ($k,$v) = split /=/, $x;
$v = url_deescape($v) if defined $v;
push @cook, $k => $v;
}
return @cook;
}
1; # OK