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sip-fsms.pl
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sip-fsms.pl
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#!/usr/bin/perl
# (c) Pali 2020-2021, Perl license
use strict;
use warnings;
use Encode qw(decode encode);
use Digest::MD5 qw(md5_hex);
use MIME::Base64 qw(encode_base64);
use Scalar::Util qw(refaddr weaken);
use Storable qw(retrieve store);
use Time::Local qw(timegm timelocal);
use Net::SIP 0.816 qw(create_rtp_sockets hostname2ip INETSOCK invoke_callback ip_canonical ip_parts2sockaddr ip_sockaddr2parts ip_string2parts laddr4dst sip_hdrval2parts sip_uri2parts);
use Number::Phone::Country 'noexport';
use Number::Phone::Lib;
# Number::Phone::Country does not export functions anymore
sub country_code { goto &Number::Phone::Country::country_code }
sub phone2country { goto &Number::Phone::Country::phone2country }
use constant PI => 4 * atan2(1, 1);
### ITU-T G.711 A-law and u-law compression ###
# ITU-T G.711:
# https://www.itu.int/rec/T-REC-G.711
# https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-G.711-198811-I!!PDF-E&type=items
my @alaw_expandtab;
my @alaw_compresstab;
my @ulaw_expandtab;
my @ulaw_compresstab;
for (0..127) {
my $alaw = ($_ < 16) ? (($_ << 4) + 8) : (((($_ & 0x0F) << 4) + 0x108) << ((($_ >> 4) & 0x07) - 1));
my $ulaw = (((($_ & 0x0F) << 3) + 0x84) << (($_ & 0x70) >> 4)) - 0x84;
$alaw_expandtab[$_ ^ 0x55] = -$alaw;
$alaw_expandtab[($_+128) ^ 0x55] = $alaw;
$ulaw_expandtab[127-$_] = -$ulaw;
$ulaw_expandtab[255-$_] = $ulaw;
}
do {
my $aval = 0;
my $uval = 0;
for (0..32767) {
push @alaw_compresstab, ($aval+128) ^ 0x55;
unshift @alaw_compresstab, $aval ^ 0x55;
push @ulaw_compresstab, 255-$uval;
unshift @ulaw_compresstab, 127-$uval;
$aval++ if $aval < 127 and $alaw_expandtab[($aval+129) ^ 0x55]-$_ < $_-$alaw_expandtab[($aval+128) ^ 0x55];
$uval++ if $uval < 127 and $ulaw_expandtab[254-$uval]-$_ < $_-$ulaw_expandtab[255-$uval];
}
};
### ITU-T V.23 Mode 2 forward channel modem ###
# ITU-T V.23:
# https://www.itu.int/rec/T-REC-V.23
# https://www.itu.int/rec/dologin_pub.asp?lang=e&id=T-REC-V.23-198811-I!!PDF-E&type=items
my $v23_freq_mark = 1300;
my $v23_freq_space = 2100;
my $v23_baud_rate = 1200;
my $v23_sample_rate = 8000;
my $v23_phase_base = 2**16;
my $v23_omega_mark = int($v23_phase_base * $v23_freq_mark / $v23_sample_rate);
my $v23_omega_space = int($v23_phase_base * $v23_freq_space / $v23_sample_rate);
my $v23_baud_base = 2**16;
my $v23_baud_incr = int($v23_baud_rate * $v23_baud_base / $v23_sample_rate);
my $v23_cos_base = 5000; # log(5000/32767) * 20 / log(10) ~~ -16.33 dB
my @v23_cos_table = map { int(cos(2 * PI * $_ / $v23_phase_base) * $v23_cos_base) } (0..$v23_phase_base-1);
my $v23_signal_trh = exp(log(10) * -35 / 20); # -35 dB
my $v23_signal_bits = 10;
my $v23_carrier_bits = 20;
my $v23_baud_pll_adj = int($v23_baud_incr / 4);
my $v23_baud_pll_trh = int($v23_baud_base / 4);
my $v23_baud_pll_init = int($v23_baud_base / 2);
my $v23_filter_steps = int($v23_sample_rate / $v23_baud_rate);
my $v23_filter_base = 2; # 2**(fls($v23_filter_steps)-1) = 2**1; sub fls { length(sprintf("%b", $_[0]))-1 }
my $v23_filter_trh = 2**13;
my @v23_filter_mark_i = map { int(cos(2 * PI * $v23_freq_mark * $_ / $v23_sample_rate) * $v23_cos_base) } (0..$v23_filter_steps-1);
my @v23_filter_mark_q = map { int(sin(2 * PI * $v23_freq_mark * $_ / $v23_sample_rate) * $v23_cos_base) } (0..$v23_filter_steps-1);
my @v23_filter_space_i = map { int(cos(2 * PI * $v23_freq_space * $_ / $v23_sample_rate) * $v23_cos_base) } (0..$v23_filter_steps-1);
my @v23_filter_space_q = map { int(sin(2 * PI * $v23_freq_space * $_ / $v23_sample_rate) * $v23_cos_base) } (0..$v23_filter_steps-1);
sub v23_dot_prod {
my ($v1, $v2) = @_;
my $prod = 0;
$prod += $v1->[$_] * $v2->[$_] for 0..$#$v1;
return $prod;
}
sub v23_encode {
my ($phase, $baud_pll, $bit) = @_;
my $omega = $bit ? $v23_omega_mark : $v23_omega_space;
my @samples;
while ($baud_pll < $v23_baud_base) {
$phase = ($phase + $omega) % $v23_phase_base;
push @samples, $v23_cos_table[$phase];
$baud_pll += $v23_baud_incr;
}
$baud_pll -= $v23_baud_base;
$_[0] = $phase;
$_[1] = $baud_pll;
return @samples;
}
sub v23_decode {
my ($buffer, $baud_pll, $prevbit, $lastbit, $sample, $synced, $wantbit) = @_;
push @{$buffer}, int($sample / $v23_filter_base);
unshift @{$buffer}, 0 until @{$buffer} > $v23_filter_steps;
shift @{$buffer};
my $corr_mark_i = int(v23_dot_prod($buffer, \@v23_filter_mark_i) / $v23_cos_base);
my $corr_mark_q = int(v23_dot_prod($buffer, \@v23_filter_mark_q) / $v23_cos_base);
my $corr_space_i = int(v23_dot_prod($buffer, \@v23_filter_space_i) / $v23_cos_base);
my $corr_space_q = int(v23_dot_prod($buffer, \@v23_filter_space_q) / $v23_cos_base);
my $sum = $corr_mark_i**2 + $corr_mark_q**2 - $corr_space_i**2 - $corr_space_q**2;
my $newbit = ($sum > $v23_filter_trh) ? 1 : ($sum < -$v23_filter_trh) ? 0 : 2;
if ($newbit != 2 and $lastbit != $newbit) {
$lastbit = $newbit;
$_[3] = $lastbit;
if (not $synced) {
$baud_pll = $v23_baud_pll_init;
} elsif ($baud_pll < $v23_baud_pll_trh) {
$baud_pll += $v23_baud_pll_adj;
} elsif ($baud_pll > $v23_baud_base - $v23_baud_pll_trh) {
$baud_pll -= $v23_baud_pll_adj;
}
}
$baud_pll += $v23_baud_incr;
$_[1] = $baud_pll;
if ($baud_pll >= $v23_baud_base and defined $wantbit and $wantbit != $newbit) {
if ($prevbit == $wantbit) {
$baud_pll += $v23_baud_incr;
} else {
$baud_pll -= $v23_baud_incr;
$_[2] = $wantbit;
}
}
return if $baud_pll < $v23_baud_base;
$baud_pll -= $v23_baud_base;
$_[1] = $baud_pll;
$_[2] = $newbit;
return $newbit;
}
sub v23_signal {
my ($buffer, $sample) = @_;
push @{$buffer}, ($sample/32767)**2;
shift @{$buffer} if @{$buffer} > $v23_signal_bits*$v23_filter_steps;
my $sum = 0;
$sum += $_ foreach @{$buffer};
return sqrt($sum / @{$buffer}) > $v23_signal_trh;
}
### Short Message transfer over PSTN/ISDN Protocol 1 ###
# SM-DLL & SM-TL:
# ETSI ES 201 912 V1.2.1 (2004-08)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=19813
# https://www.etsi.org/deliver/etsi_es/201900_201999/201912/01.02.01_60/es_201912v010201p.pdf
# SM-DLL transmission:
# ETSI EN 300 659-2 V1.3.1 (2001-01)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=7973
# https://www.etsi.org/deliver/etsi_en/300600_300699/30065902/01.03.01_60/en_30065902v010301p.pdf
# SM-PL transmission:
# ETSI EN 300 659-1 V1.3.1 (2001-01)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=7972
# https://www.etsi.org/deliver/etsi_en/300600_300699/30065901/01.03.01_60/en_30065901v010301p.pdf
# SM-DLL receiving:
# ETSI ES 200 778-2 V1.2.2 (2002-11)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=16160
# https://www.etsi.org/deliver/etsi_es/200700_200799/20077802/01.02.02_60/es_20077802v010202p.pdf
# SM-PL receiving:
# ETSI ES 200 778-1 V1.2.2 (2002-11)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=16158
# https://www.etsi.org/deliver/etsi_es/200700_200799/20077801/01.02.02_60/es_20077801v010202p.pdf
my $smpl_mark_signal_bits = 80;
my $smpl_mark_signal_bits_min = $smpl_mark_signal_bits-25;
my $smpl_cheksum_mark_bits = 10;
sub smpl_encode {
my ($phase, $baud_pll, $byte) = @_;
my @samples;
push @samples, v23_encode($phase, $baud_pll, 0);
push @samples, v23_encode($phase, $baud_pll, $_) foreach split //, unpack('b*', chr($byte));
push @samples, v23_encode($phase, $baud_pll, 1);
$_[0] = $phase;
$_[1] = $baud_pll;
return @samples;
}
my %smdll_types = (
DATA => 0x11,
ERROR => 0x12,
EST => 0x13,
REL => 0x14,
ACK => 0x15,
NACK => 0x16,
);
my %smdll_codes = reverse %smdll_types;
sub smdll_encode {
my ($noext, $type, $payload) = @_;
my @payload = defined $payload ? unpack('C*', $payload) : ();
die "Type for SM-DLL message must be in range 0x00-0x7F\n" unless $type >= 0x00 and $type <= 0x7F;
die "Payload for SM-DLL message cannot be larger than 176 bytes\n" if @payload > 176;
$type |= 0b10000000 if $noext;
my $checksum = 0;
$checksum += $_ foreach $type, scalar @payload, @payload;
$checksum = (-$checksum) & 0xFF;
my @samples;
my $phase = 0;
my $baud_pll = 0;
push @samples, v23_encode($phase, $baud_pll, 0);
push @samples, v23_encode($phase, $baud_pll, 1) for 1..$smpl_mark_signal_bits;
push @samples, smpl_encode($phase, $baud_pll, $type);
push @samples, smpl_encode($phase, $baud_pll, scalar @payload);
push @samples, smpl_encode($phase, $baud_pll, $_) foreach @payload;
push @samples, smpl_encode($phase, $baud_pll, $checksum);
push @samples, v23_encode($phase, $baud_pll, 1) for 1..$smpl_cheksum_mark_bits;
return @samples;
}
my %smdll_decode_error_types = (
NO_ERROR => 0,
LOST_SIGNAL => 1,
LOST_CARRIER => 2,
BROKEN_START_BIT => 3,
BROKEN_STOP_BIT => 4,
WRONG_CHECKSUM => 5,
WRONG_LENGTH => 6,
);
my %smdll_decode_error_codes = reverse %smdll_decode_error_types;
sub smdll_decode {
my ($state, $sample) = @_;
my $had_carrier = (defined $state->{carrier_bits} and $state->{carrier_bits} >= $v23_carrier_bits);
$state->{signal_buffer} = [] unless exists $state->{signal_buffer};
my $has_signal = v23_signal($state->{signal_buffer}, $sample);
if (not $has_signal) {
my $ignore_lost = $state->{ignore_lost};
my $had_signal = $state->{had_signal};
$state->{ignore_lost} = 0;
$state->{had_signal} = 0;
$state->{mark_bits} = 0;
$state->{had_mark_signal} = 0;
return ($had_signal and not $ignore_lost) ? $smdll_decode_error_types{LOST_SIGNAL} : ();
} elsif (not $state->{had_signal}) {
$state->{ignore_lost} = 0;
$state->{had_signal} = 1;
$state->{filter_buffer} = [];
$state->{baud_pll} = 0;
$state->{prevbit} = 2;
$state->{lastbit} = 2;
$state->{carrier_bits} = 0;
$state->{mark_bits} = 0;
$state->{had_mark_signal} = 0;
$state->{skip_mark_bits} = 0;
$state->{smdll_bits} = [];
$state->{smdll_buffer} = [];
}
my $wantbit = (@{$state->{smdll_bits}} == 0 ? 0 : @{$state->{smdll_bits}} == 9 ? 1 : undef);
my $newbit = v23_decode($state->{filter_buffer}, $state->{baud_pll}, $state->{prevbit}, $state->{lastbit}, $sample, $state->{had_mark_signal}, $wantbit);
if (defined $newbit) {
if ($newbit == 0 or $newbit == 1) {
$state->{carrier_bits}++;
} else {
$state->{carrier_bits} = 0;
}
if ($state->{skip_mark_bits} > 0) {
if ($newbit == 1) {
$newbit = undef;
$state->{skip_mark_bits}--;
} else {
$state->{skip_mark_bits} = 0;
}
}
}
return unless defined $newbit;
my $has_carrier = $state->{carrier_bits} >= $v23_carrier_bits;
if (not $has_carrier) {
my $ignore_lost = $state->{ignore_lost};
$state->{ignore_lost} = 1;
$state->{mark_bits} = 0;
$state->{had_mark_signal} = 0;
$state->{skip_mark_bits} = 0;
return ($had_carrier and not $ignore_lost) ? $smdll_decode_error_types{LOST_CARRIER} : ();
} elsif (not $had_carrier) {
$state->{ignore_lost} = 0;
$state->{mark_bits} = 0;
$state->{had_mark_signal} = 0;
$state->{smdll_bits} = [];
$state->{smdll_buffer} = [];
}
if (not $state->{had_mark_signal}) {
if ($newbit == 1) {
$state->{mark_bits}++;
} elsif ($state->{mark_bits} >= $smpl_mark_signal_bits_min) {
$state->{had_mark_signal} = 1;
} else {
$state->{mark_bits} = 0;
}
}
return unless $state->{had_mark_signal};
if (@{$state->{smdll_bits}} == 9) {
if ($newbit != 1) {
$state->{ignore_lost} = 1;
$state->{mark_bits} = 0;
$state->{had_mark_signal} = 0;
$state->{smdll_buffer} = [];
return $smdll_decode_error_types{BROKEN_STOP_BIT};
}
push @{$state->{smdll_buffer}}, ord(pack('b*', join '', @{$state->{smdll_bits}}[1..8]));
$state->{smdll_bits} = [];
} else {
if (@{$state->{smdll_bits}} == 0 and $newbit != 0) {
$state->{ignore_lost} = 1;
$state->{mark_bits} = 0;
$state->{had_mark_signal} = 0;
$state->{smdll_buffer} = [];
return $smdll_decode_error_types{BROKEN_START_BIT};
}
push @{$state->{smdll_bits}}, $newbit;
}
return unless @{$state->{smdll_buffer}} >= 2;
my $length = $state->{smdll_buffer}->[1];
return unless @{$state->{smdll_buffer}} == $length + 3;
my $checksum = pop @{$state->{smdll_buffer}};
my $exp_checksum = 0;
$exp_checksum += $_ foreach @{$state->{smdll_buffer}};
$exp_checksum = (-$exp_checksum) & 0xFF;
my $type = shift @{$state->{smdll_buffer}};
my $noext = ($type & 0b10000000) ? 1 : 0;
$type &= 0b01111111;
shift @{$state->{smdll_buffer}};
my $payload = ($length > 0) ? pack('C*', @{$state->{smdll_buffer}}) : undef;
my $status = $smdll_decode_error_types{NO_ERROR};
$status = $smdll_decode_error_types{WRONG_LENGTH} if $length > 176;
$status = $smdll_decode_error_types{WRONG_CHECKSUM} if $checksum != $exp_checksum;
$state->{ignore_lost} = 1;
$state->{mark_bits} = 0;
$state->{had_mark_signal} = 0;
$state->{skip_mark_bits} = 10;
$state->{smdll_buffer} = [];
return $status, $noext, $type, $payload, $checksum;
}
my %smdll_error_types = (
WRONG_CHECKSUM => 0x01,
WRONG_LENGTH => 0x02,
UNKNOWN_TYPE => 0x03,
UNSUPP_EXT => 0x04,
UNSPEC_CAUSE => 0xFF,
);
my %smdll_error_codes = reverse %smdll_error_types;
sub smdll_encode_error {
my ($code) = @_;
return smdll_encode(1, $smdll_types{ERROR}, chr($code));
}
sub smdll_encode_est {
return smdll_encode(1, $smdll_types{EST});
}
sub smdll_encode_rel {
return smdll_encode(1, $smdll_types{REL});
}
sub smdll_encode_ack {
my ($tpdu) = @_;
die "TPDU for ACK SM-DLL message cannot be larger than 176 bytes\n" if defined $tpdu and length $tpdu > 176;
return smdll_encode(1, $smdll_types{ACK}, $tpdu);
}
sub smdll_encode_nack {
my ($tpdu) = @_;
die "TPDU for NACK SM-DLL message cannot be larger than 176 bytes\n" if defined $tpdu and length $tpdu > 176;
return smdll_encode(1, $smdll_types{NACK}, $tpdu);
}
sub smtl_decode_data {
my ($smtl_buffer, $noext, $type, $payload) = @_;
return $payload unless $type == $smdll_types{DATA};
if (not $noext) {
${$smtl_buffer} = '' unless defined ${$smtl_buffer};
${$smtl_buffer} .= $payload;
return;
}
if ($noext and defined ${$smtl_buffer}) {
$payload = ${$smtl_buffer} . $payload;
${$smtl_buffer} = undef;
}
return $payload;
}
sub smtl_encode_data {
my ($tpdu) = @_;
my @payloads = defined $tpdu ? unpack('(a176)*', $tpdu) : ();
my $last_payload = pop @payloads;
my @samples;
push @samples, [ smdll_encode(0, $smdll_types{DATA}, $_) ] foreach @payloads;
push @samples, [ smdll_encode(1, $smdll_types{DATA}, $last_payload) ];
return @samples;
}
### GSM Short Message Transfer Layer ###
# SM-TL/TPDU:
# 3GPP TS 23.040
# https://www.3gpp.org/dynareport/23040.htm
# ETSI TS 123 040 V16.0.0 (2020-07)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=60072
# https://www.etsi.org/deliver/etsi_ts/123000_123099/123040/16.00.00_60/ts_123040v160000p.pdf
# ETSI TS 123 040 V3.5.0 (2000-07)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=11369
# https://www.etsi.org/deliver/etsi_ts/123000_123099/123040/03.05.00_60/ts_123040v030500p.pdf
# GSM 03.40
# https://www.3gpp.org/dynareport/0340.htm
# ETSI GTS 03.40 V3.7.0 (1995-01)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=1546
# https://www.etsi.org/deliver/etsi_gts/03/0340/03.07.00_60/gsmts_0340sv030700p.pdf
# TP-DCS & 7bit enc:
# 3GPP TS 23.038
# https://www.3gpp.org/dynareport/23038.htm
# ETSI TS 123 038 V16.0.0 (2020-07)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=60070
# https://www.etsi.org/deliver/etsi_ts/123000_123099/123038/16.00.00_60/ts_123038v160000p.pdf
# TP-UD compression:
# 3GPP TS 23.042
# https://www.3gpp.org/dynareport/23042.htm
# ETSI TS 123 042 V16.0.0 (2020-07)
# https://portal.etsi.org/webapp/workprogram/Report_WorkItem.asp?WKI_ID=60075
# https://www.etsi.org/deliver/etsi_ts/123000_123099/123042/16.00.00_60/ts_123042v160000p.pdf
my @tpdu_bcd_digits_dec_tab = ('0'..'9', ('0') x 6);
my @tpdu_bcd_dec_tab = ('0'..'9', '*', '#', 'a'..'c', '');
my %tpdu_bcd_enc_tab = map{ (lc $tpdu_bcd_dec_tab[$_] => $_, uc $tpdu_bcd_dec_tab[$_] => $_) } (0..$#tpdu_bcd_dec_tab);
sub tpdu_decode_semioctet {
my $h1 = ord($_[0]) & 0b00001111;
my $h2 = (ord($_[0]) & 0b11110000) >> 4;
return $tpdu_bcd_dec_tab[$h1] . $tpdu_bcd_dec_tab[$h2];
}
sub tpdu_decode_semioctet_digits {
my $h1 = ord($_[0]) & 0b00001111;
my $h2 = (ord($_[0]) & 0b11110000) >> 4;
return $tpdu_bcd_digits_dec_tab[$h1] . $tpdu_bcd_digits_dec_tab[$h2];
}
sub tpdu_encode_semioctet {
my $h1 = substr $_[0], 0, 1;
my $h2 = substr $_[0], 1, 1;
my $t1 = exists $tpdu_bcd_enc_tab{$h1} ? $tpdu_bcd_enc_tab{$h1} : $tpdu_bcd_enc_tab{''};
my $t2 = exists $tpdu_bcd_enc_tab{$h2} ? $tpdu_bcd_enc_tab{$h2} : $tpdu_bcd_enc_tab{''};
return chr($t1 | ($t2 << 4));
}
sub tpdu_decode_7bit {
return encode('UTF-8', decode('GSM0338', substr(pack('(b*)*', unpack '(a7)*', unpack 'b*', $_[0]), 0, $_[1])));
}
sub tpdu_encode_7bit {
my $bytes = encode('GSM0338', decode('UTF-8', $_[0]));
my $len = length $bytes;
my $septets = pack 'b*', join '', map { substr $_, 0, 7 } unpack '(a8)*', unpack 'b*', $bytes;
return ($septets, $len);
}
sub tpdu_decode_address {
my ($address) = @_;
return unless length $address >= 2;
my $number_len = ord(substr $address, 0, 1);
my $address_type = ord(substr $address, 1, 1);
my $number_type = ($address_type & 0b01110000) >> 4;
my $number_plan = ($address_type & 0b00001111);
my $address_len = 2 + int(($number_len+1)/2);
return unless $address_len <= 12;
return unless length $address >= $address_len;
my $address_value = substr $address, 2, $address_len-2;
my $first = ord(substr $address_value, 0, 1);
$first = (($first & 0b00001111) << 4) | (($first & 0b11110000) >> 4);
my $number_value;
if ($number_type == 0b101) {
$number_value = tpdu_decode_7bit($address_value, $address_len-2);
} elsif ($number_type == 0b000 and $number_plan == 0b1001 and ($first & 0b11100000) == 0b00000000 and ($first & 0b00011111) == $number_len-2) {
# Special undocumented GSM 7bit encoding for F-SMS TPDU address used in Czech Republic:
# Bytes are encoded as semioctets, first encoded byte has upper 3 bits unset,
# lower 5 bits of first byte represents number of following semioctets
# and the rest encoded bytes contain GSM 7bit septets packed as bytes.
$address_value = join '', map { chr(((ord($_) & 0b00001111) << 4) | ((ord($_) & 0b11110000) >> 4)) } split //, $address_value;
# one semioctet is 4 bits long, one septet is 7 bits long
my $septets_len = int(ord(substr $address_value, 0, 1, '') * 4 / 7);
$septets_len = $address_len-2 if $septets_len > $address_len-2;
$number_value = tpdu_decode_7bit($address_value, $septets_len);
$number_type = 0b101;
} elsif ($number_type == 0b000 and $number_plan == 0b1001) {
# Special undocumented Alphabet encoding for F-SMS TPDU address used in Czech Republic:
# ASCII characters are encoded as semioctets by storing only low 4 bits of each character.
# ASCII 'A'=0x41, (0x41 & 0b1111) = 1; ASCII 'B'=0x42, (0x42 & 0b1111) = 2; ...
# ASCII 'a'=0x61, (0x61 & 0b1111) = 1; ASCII 'b'=0x62, (0x62 & 0b1111) = 2; ...
# ASCII 'N'=0x4E, 'n'=0x6E, '.'=0x2E and all those characters have number 14 in low 4 bits.
# Decoding is ambiguous, so decode all semioctets as ASCII 'A' - 'P' characters only.
# In most cases TPDU address contains only letters, so this is the best approximation.
$number_value = substr(join('', map { chr(ord("A") + ($_ + 16 - 1) % 16) } map { (ord($_) & 0b1111), (ord($_) >> 4) } split //, $address_value), 0, $number_len);
$number_type = 0b101;
} else {
$number_value = substr(join('', map { tpdu_decode_semioctet($_) } split //, $address_value), 0, $number_len);
}
$number_value = "+$number_value" if $number_type == 0b001 and $number_value =~ /^[1-9][0-9]+$/;
return ([$number_value, $number_type, $number_plan], $address_len);
}
sub tpdu_encode_address {
my ($number, $type, $plan) = @_;
$type = ($number =~ /^(?:\+|00)[1-9][0-9]+$/) ? 0b001 : ($number =~ /^[0-9]+$/) ? 0b000 : 0b101 unless defined $type;
$plan = ($number =~ /^\+?[0-9]+$/) ? 0b0001 : 0b0000 unless defined $plan;
$number = $1 if $number =~ /^(?:\+|00)([1-9][0-9]+)$/ and $type == 0b001;
die "TPDU number type $type is not in range 0b000 ... 0b111\n" if $type < 0 or $type > 0b111;
die "TPDU number plan $plan is not in range 0b0000 ... 0b1111\n" if $plan < 0 or $plan > 0b1111;
my ($sep, $sep_len) = ($type == 0b101) ? tpdu_encode_7bit($number) : ();
my $address = '';
$address .= chr($type == 0b101 ? ($sep_len*7+3)/4 : length $number);
$address .= chr(0b10000000 | ($type << 4) | $plan);
if ($type == 0b101) {
$address .= $sep;
} else {
die "TPDU number type $type cannot contain non-numeric characters\n" unless $number =~ /^[0-9*#a-cA-C]*$/;
$address .= tpdu_encode_semioctet($_) foreach unpack '(a2)*', $number;
}
die "TPDU number is too long\n" unless length $address <= 12;
return $address;
}
sub tpdu_is_command {
my ($dir, $tpdu) = @_;
# Reject $tpdu as command if it does not have command/status type
return 0 unless length $tpdu >= 1;
my $first = ord(substr $tpdu, 0, 1);
my $mti = ($first & 0b00000011);
return 0 unless $mti == 2;
# Accept/reject $tpdu as command if we know direction of $tpdu
return $dir == 1 if defined $dir;
# Reject $tpdu as command if it does not have valid command structure length
return 0 unless length $tpdu >= 8;
my $addr1_len = ord(substr $tpdu, 5, 1);
return 0 unless length $tpdu > 7+$addr1_len;
my $cd_len = ord(substr $tpdu, 7+$addr1_len, 1);
return 0 unless length $tpdu >= 8+$addr1_len+$cd_len;
# Accept $tpdu as command if it does not have valid status structure length or valid status timestamps
my $addr2_len = ord(substr $tpdu, 2, 1);
return 1 if length $tpdu < 14+$addr2_len;
my $scts = tpdu_decode_ts(substr $tpdu, 4+$addr2_len, 7);
return 1 if not defined $scts;
my $dt = tpdu_decode_ts(substr $tpdu, 11+$addr2_len, 7);
return 1 if not defined $scts;
# Reject $tpdu as command if it has set some reserved bits
return 0 if $first & 0b10011100;
# Accept $tpdu as command if $tpdu length matches structure length
return length $tpdu == 8+$addr1_len+$cd_len;
}
sub tpdu_is_fragmented {
my ($tpdu) = @_;
return unless length $tpdu > 0;
my $first = ord(substr $tpdu, 0, 1);
my $has_udh = ($first & 0b01000000) ? 1 : 0;
return unless $has_udh;
my $mti = ($first & 0b00000011);
my $vpf = ($mti == 1) ? (($first & 0b00011000) >> 3) : 0;
my $offset = 1;
$offset += 1 unless $mti == 0 or $mti == 3;
return unless length $tpdu > $offset;
my ($num, $addr_len) = tpdu_decode_address(substr $tpdu, $offset);
return unless defined $num and $addr_len > 0;
$offset += $addr_len;
$offset += 15 if $mti == 2;
$offset += 2;
$offset += 7 if $mti == 0 or $mti == 3;
$offset += 1 if $vpf == 2;
$offset += 7 if $vpf == 3 or $vpf == 1;
return unless length $tpdu > $offset;
my $udl = ord(substr $tpdu, $offset, 1);
$offset += 1;
return unless length $tpdu > $offset;
my $udhl = ord(substr $tpdu, $offset, 1);
$offset += 1;
return unless length $tpdu >= $offset + $udhl;
my $udh = substr $tpdu, $offset, $udhl;
$offset = 0;
my ($ref_num, $max_num, $seq_num);
while (length $udh >= $offset + 2) {
my $udh_ei = ord(substr $udh, $offset++, 1);
my $udh_el = ord(substr $udh, $offset++, 1);
last unless length $udh >= $offset + $udh_el;
my $udh_ed = substr $udh, $offset, $udh_el;
$offset += $udh_el;
next unless $udh_ei == 0x00 or $udh_ei == 0x16;
next if $udh_ei == 0x00 and $udh_el != 3;
next if $udh_ei == 0x16 and $udh_el != 4;
$ref_num = ord(substr $udh_ed, 0, 1, '');
$ref_num = ($ref_num << 8) | ord(substr $udh_ed, 0, 1, '') if $udh_ei == 0x16;
$max_num = ord(substr $udh_ed, 0, 1, '');
$seq_num = ord(substr $udh_ed, 0, 1, '');
}
return unless defined $ref_num;
return [ $mti, $num->[0], $ref_num, $max_num, $seq_num ];
}
my @month_days = (31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
sub tpdu_decode_ts {
my ($ts) = @_;
return unless length $ts == 7;
my @ts = split //, $ts;
my $sign = (ord($ts[6]) & 0b00001000) ? '-' : '+';
$ts[6] = chr(ord($ts[6]) & 0b11110111);
my @nums = map { tpdu_decode_semioctet_digits($_) } @ts;
return unless $nums[1] >= 1 and $nums[1] <= 12 and $nums[2] >= 1 and $nums[2] <= $month_days[$nums[1]-1] and $nums[3] <= 23 and $nums[4] <= 59 and $nums[5] <= 59;
$nums[0] = ($nums[0] < 70) ? "20$nums[0]" : "19$nums[0]";
my $tz = $nums[6] * 15;
$sign = '' unless $tz;
return [ @nums[0..5], $sign, sprintf('%02u', int($tz/60)), sprintf('%02u', $tz%60) ];
}
sub tpdu_encode_ts {
my (@ts) = @_;
die "TPDU timestamp must contain 9 elements\n" unless @ts == 9;
die "TPDU timestamp year is invalid\n" unless ($ts[0] >= 0 and $ts[0] <= 99) or ($ts[0] >= 1970 and $ts[0] <= 2069);
die "TPDU timestamp month is invalid\n" unless $ts[1] >= 1 and $ts[1] <= 12;
die "TPDU timestamp day is invalid\n" unless $ts[2] >= 1 and $ts[2] <= $month_days[$ts[1]-1];
die "TPDU timestamp hour is invalid\n" unless $ts[3] >= 0 and $ts[3] <= 23;
die "TPDU timestamp minute is invalid\n" unless $ts[4] >= 0 and $ts[4] <= 59;
die "TPDU timestamp second is invalid\n" unless $ts[5] >= 0 and $ts[5] <= 59;
substr $ts[0], 0, -2, '';
my $sign = splice @ts, 6, 1;
$sign = '' if $sign eq '+';
die "TPDU timestamp timezone sign is invalid\n" unless $sign eq '-' or $sign eq '';
die "TPDU timestamp elements must contain 2 digits\n" unless 8 == grep { $_ =~ /^[0-9]{1,2}$/ } @ts;
my ($hours, $minutes) = splice @ts, 6, 2;
push @ts, int(($hours*60 + $minutes)/15);
die "TPDU timestamp timezone is invalid\n" unless $ts[6] <= 79;
my $ts = '';
$ts .= tpdu_encode_semioctet($_) foreach unpack '(a2)*', join '', map { sprintf '%02u', $_ } @ts;
substr $ts, 6, 1, chr(ord(substr $ts, 6, 1) | 0b00001000) if $sign eq '-';
return $ts;
}
sub tpdu_decode_vp {
my ($vp, $vpf) = @_;
return unless defined $vpf;
if ($vpf == 0) {
return ([0, 0], 0);
} elsif ($vpf == 2) {
return unless length $vp >= 1;
my $num = ord(substr $vp, 0, 1);
if ($num <= 143) {
$num = ($num+1)*5*60;
} elsif ($num <= 167) {
$num = 12*60*60 + ($num-143)*30*60;
} elsif ($num <= 196) {
$num = ($num-166)*24*60*60;
} else {
$num = ($num-192)*7*24*60*60;
}
return ([0, 1, $num], 1);
} elsif ($vpf == 3) {
return unless length $vp >= 7;
return ([0, 2, tpdu_decode_ts(substr $vp, 0, 7)], 7);
} elsif ($vpf == 1) {
return unless length $vp >= 7;
my $vpi = ord(substr $vp, 0, 1);
my $ext = ($vpi & 0b10000000) ? 1 : 0;
my $single = ($vpi & 0b01000000) ? 1 : 0;
my $format = ($vpi & 0b00000111);
if ($format == 0) {
return ([$single, 0], 7);
} elsif ($ext) {
return ([$single, 0], 7);
} elsif ($format == 1) {
my ($rel, undef) = tpdu_decode_vp(substr($vp, 1, 1), 2);
return ([$single, 1, $rel->[2]], 7);
} elsif ($format == 2) {
return ([$single, 1, ord(substr $vp, 1, 1)], 7);
} elsif ($format == 3) {
my @time = map { tpdu_decode_semioctet_digits($_) } split //, substr $vp, 1, 3;
return ([$single, 1, $time[0]*60*60 + $time[1]*60 + $time[2]], 7);
} else {
return ([$single, 0], 7);
}
} else {
return;
}
}
sub tpdu_encode_vp {
my (@vp) = @_;
return (0, '') unless @vp;
die "TPDU validity period must contain 3 elements\n" unless @vp == 3;
my $vpf;
my $vp;
if ($vp[1] == 2) {
die "TPDU single shot cannot be used for absolute validity period\n" if $vp[0];
$vpf = 3;
$vp = tpdu_encode_ts(@{$vp[2]});
} elsif (not $vp[0] and $vp[1] == 1 and $vp[2] <= (143+1)*5*60 and $vp[2] % (5*60) == 0) {
$vpf = 2;
$vp = chr(int($vp[2]/(5*60))+1);
} elsif (not $vp[0] and $vp[1] == 1 and $vp[2] >= 12*60*60 + (144-143)*30*60 and $vp[2] <= 12*60*60 + (167-143)*30*60 and ($vp[2] - 12*60*60) % (30*60) == 0) {
$vpf = 2;
$vp = chr(int(($vp[2] - 12*60*60) / (30*60)) + 143);
} elsif (not $vp[0] and $vp[1] == 1 and $vp[2] >= (168-166)*24*60*60 and $vp[2] <= (196-166)*24*60*60) {
$vpf = 2;
$vp = chr(int($vp[2]/(24*60*60)) + 166);
} elsif (not $vp[0] and $vp[1] == 1 and $vp[2] >= (167-192)*7*24*60*60 and $vp[2] <= (255-192)*7*24*60*60) {
$vpf = 2;
$vp = chr(int($vp[2]/(7*24*60*60)) + 192);
} elsif (not $vp[0] and $vp[1] == 1 and $vp[2] > (255-192)*7*24*60*60) {
$vpf = 2;
$vp = chr(255);
} elsif (not $vp[0] and $vp[1] == 0) {
$vpf = 0;
$vp = '';
} else {
$vpf = 1;
my $vpi = 0;
$vpi |= 0b01000000 if $vp[0];
if ($vp[1] == 0) {
$vpi |= 0b00000000;
} elsif ($vp[2] < 256) {
$vpi |= 0b00000010;
$vp = chr($vp[2]);
} elsif ($vp[2] < 24*60*60) {
$vpi |= 0b00000011;
$vp = '';
$vp .= tpdu_encode_semioctet(sprintf "%02u", int($vp[2]/(60*60)));
$vp .= tpdu_encode_semioctet(sprintf "%02u", int($vp[2]/60) % 60);
$vp .= tpdu_encode_semioctet(sprintf "%02u", $vp[2] % 60);
} else {
$vpi |= 0b00000001;
if ($vp[2] <= (196-166)*24*60*60) {
$vp = chr(int($vp[2]/(24*60*60)) + 166);
} elsif ($vp[2] <= (255-192)*7*24*60*60) {
$vp = chr(int($vp[2]/(7*24*60*60)) + 192);
} else {
$vp = chr(255);
}
}
$vp = chr($vpi) . $vp;
$vp .= chr(0) x (7-length($vp));
}
return ($vpf, $vp);
}
sub tpdu_decode_st {
my $st = ord($_[0]);
$st = 0b01100011 if $st & 0b10000000;
return [($st >> 5), ($st & 0b00011111)];
}
sub tpdu_encode_st {
return chr((($_[0] & 0b00000111) << 5) | ($_[1] & 0b00011111));
}
sub tpdu_decode_dcs {
my $dcs = ord($_[0]);
my $mc = ((($dcs & 0b10010000) == 0b00010000) || (($dcs & 0b11110000) == 0b11110000)) ? ($dcs & 0b00000011) : undef;
my $cd = (($dcs & 0b10100000) == 0b00100000) ? 1 : 0;
my $ad = (($dcs & 0b11000000) == 0b01000000) ? 1 : 0;
my $it = ((($dcs & 0b11100000) == 0b11000000) || (($dcs & 0b11110000) == 0b11100000)) ? ($dcs & 0b00000011) : undef;
my $is = ((($dcs & 0b11100000) == 0b11000000) || (($dcs & 0b11110000) == 0b11100000)) ? (($dcs & 0b00001000) ? 1 : 0) : undef;
my $id = ((($dcs & 0b11100000) == 0b11000000) || (($dcs & 0b11110000) == 0b11100000)) ? ((($dcs & 0b11110000) == 0b11000000) ? 1 : 0) : undef;
my $is_ucs2 = ((((($dcs & 0b10000000) == 0b00000000) || (($dcs & 0b11110000) == 0b11110000)) && (($dcs & 0b00001100) == 0b00001000)) || (($dcs & 0b11110000) == 0b11100000)) ? 1 : 0;
my $is_8bit = (((($dcs & 0b10000000) == 0b00000000) || (($dcs & 0b11110000) == 0b11110000)) && (($dcs & 0b00001100) == 0b00000100)) ? 1 : 0;
return ($mc, $ad, (defined $it ? [$it, undef, $is, $id, undef] : undef), ($is_ucs2 ? 2 : $is_8bit ? 1 : 0), $cd);
}
sub tpdu_encode_dcs {
my ($mc, $ad, $mwi, $ud_isbin, $ud_cd, $data, $ud_ucs2) = @_;
die "TPDU message class is invalid\n" if defined $mc and ($mc < 0 or $mc > 3);
die "TPDU message class and message waiting indicator cannot be used together\n" if defined $mc and defined $mwi;
die "TPDU binary data cannot contain wide characters\n" if $ud_isbin and defined $data and $data =~ /[^\x00-\xff]/;
my $ud_enc = $ud_isbin ? 1 : (defined $ud_ucs2) ? ($ud_ucs2 ? 2 : 0) : (not defined $data) ? 0 : eval { encode('GSM0338', decode('UTF-8', $data), 1); 1 } ? 0 : 2;
my $dcs = 0;
if (defined $mwi) {
$dcs |= 0b11000000;
$dcs |= ($mwi->[0] & 0b11);
$dcs |= 0b00001000 if $mwi->[1];
die "TPDU message waiting indicator cannot be used with binary data\n" if $ud_enc == 1;
die "TPDU message waiting indicator cannot be used together with compression\n" if $ud_cd;
die "TPDU message waiting indicator and automatic deletion cannot be used with UCS-2 data\n" if $ad and $ud_enc == 2;
$dcs |= ($ud_enc == 2 ? 0b00100000 : 0b00010000) unless $ad;
} else {
if (defined $mc) {
$dcs |= 0b00010000;
$dcs |= $mc;
}
$dcs |= 0b01000000 if $ad;
$dcs |= 0b00100000 if $ud_cd;
$dcs |= ($ud_enc << 2);
}
return (chr($dcs), $ud_enc);
}
sub tpdu_decompress_ud {
# TODO
return 'UNSUPPORTED COMPRESSED DATA: ' . join '', map { sprintf '\\x%02x', ord($_) } split //, $_[0];
}
sub tpdu_compress_ud {
# TODO
}
sub tpdu_decode_ud {
my ($ud, $has_udh, $udl, $ud_enc, $ud_cd) = @_;
my ($mwis, $port, $wcmp, $ehl, $ra, $nlss, $nlls);
my $fragmented;
if ($has_udh) {
return unless length $ud >= 1;
my $udhl = ord(substr $ud, 0, 1, '');
return unless length $ud >= $udhl;
my $udh = substr $ud, 0, $udhl, '';
while (length $udh >= 2) {
my $udh_ei = ord(substr $udh, 0, 1, '');
my $udh_el = ord(substr $udh, 0, 1, '');
last unless length $udh >= $udh_el;
my $udh_ed = substr $udh, 0, $udh_el, '';
if ($udh_ei == 0x00 or $udh_ei == 0x08) { # Concatenated short messages
$fragmented = 1;
} elsif ($udh_ei == 0x01 and $udh_el == 2) { # Special SMS Message Indication
my $first = ord(substr $udh_ed, 0, 1, '');
my $count = ord(substr $udh_ed, 0, 1, '');
my $type = ($first & 0b00000011);
my $type_ext = ($first & 0b00011100) >> 2;
my $profile = ($first & 0b01100000) >> 5;
my $discard = ($first & 0b10000000) ? 1 : 0;
$mwis = [] unless defined $mwis;
push @{$mwis}, [$type, $type_ext, $count, $discard, $profile];
} elsif (($udh_ei == 0x04 and $udh_el == 2) or ($udh_ei == 0x05 and $udh_el == 4)) { # Application port addressing scheme
my $dp = ord(substr $udh_ed, 0, 1, '');
$dp = ($dp << 8) | ord(substr $udh_ed, 0, 1, '') if $udh_ei == 0x05;
my $op = ord(substr $udh_ed, 0, 1, '');
$op = ($op << 8) | ord(substr $udh_ed, 0, 1, '') if $udh_ei == 0x05;
$port = [ $dp, $op ];
} elsif ($udh_ei == 0x09) { # Wireless Control Message Protocol
$wcmp = $udh_ed;
} elsif ($udh_ei == 0x20 and $udh_el == 1) { # RFC 5322 E-Mail Header
$ehl = ord($udh_ed);
} elsif ($udh_ei == 0x22) { # Reply Address Element
($ra) = tpdu_decode_address($udh_ed);
} elsif ($udh_ei == 0x23) { # Enhanced Voice Mail Information
# TODO
} elsif ($udh_ei == 0x24 and $udh_el == 1) { # National Language Single Shift
$nlss = ord($udh_ed);
} elsif ($udh_ei == 0x25 and $udh_el == 1) { # National Language Locking Shift
$nlls = ord($udh_ed);
}
}
$udl -= $udhl+1;
if ($ud_enc == 2) {
substr $ud, 0, ($udhl+1)%2, '';
} elsif ($ud_enc == 0) {
my $plen = (7-(($udhl+1)*8)%7)%7;
if ($plen) {
my $unud = unpack('b*', $ud);
if (length $unud > $plen) {
$ud = pack 'b*', substr $unud, $plen;
} else {
$ud = '';
}
if ($udl > $plen) {
$udl -= $plen;
} else {
$udl = 0;
}
}
}
}
if ($ud_cd) {
$ud = substr $ud, 0, $udl;
$ud = tpdu_decompress_ud($ud) unless $fragmented;
} elsif ($ud_enc == 2) {
my $bom = (length $ud >= 2) ? (substr $ud, 0, 2, '') : '';
my $enc;
if ($bom eq "\xFF\xFE") {
$enc = 'UTF-16LE';
$udl -= 2;
} elsif ($bom eq "\xFE\xFF") {
$enc = 'UTF-16BE';
$udl -= 2;
} else {
$enc = 'UTF-16BE';
$ud = $bom.$ud;
}
$ud = encode('UTF-8', decode($enc, substr $ud, 0, $udl));
} elsif ($ud_enc == 1) {
$ud = substr $ud, 0, $udl;
} else {
# TODO: decode using $nlss and $nlls
$ud = tpdu_decode_7bit($ud, $udl);
}
return ($ud, $mwis, $port, $wcmp, $ehl, $ra);
}
sub tpdu_encode_ud {
my ($udh, $ud_enc, $data) = @_;
$udh = '' unless defined $udh;
$data = '' unless defined $data;
my ($ud, $udl);
if ($ud_enc == 2) {
$ud = encode('UTF-16BE', decode('UTF-8', $data));
$udl = length $ud;
} elsif ($ud_enc == 1) {
$ud = $data;
$udl = length $ud;
} else {
($ud, $udl) = tpdu_encode_7bit($data);
}
if (length $udh) {
if ($ud_enc == 2 and length($udh) % 2 == 1) {
$udh .= chr(0);
} elsif ($ud_enc == 0) {
my $plen = (7-(length($udh)*8)%7)%7;
$ud = pack 'b*', ('0' x $plen) . unpack 'b*', $ud if $plen;
}
$udl += ($ud_enc == 0) ? (length($udh)*8+6)/7 : length($udh);
}
die "TPDU user data are larger than 140 bytes\n" if length($udh) + length($ud) > 140;
return chr($udl) . $udh . $ud;
}
sub tpdu_decode {
my ($tpdu) = @_;
return unless length $tpdu >= 1;
my $first = ord(substr $tpdu, 0, 1, '');
my $mti = ($first & 0b00000011);
my $is_deliver = $mti == 0 || $mti == 3;
my $is_submit = $mti == 1;
my $is_status = $mti == 2;
my $mms = $is_submit ? undef : (($first & 0b00000100) ? 0 : 1);
my $rd = $is_submit ? (($first & 0b00000100) ? 1 : 0) : undef;
my $vpf = $is_submit ? (($first & 0b00011000) >> 3) : undef;
my $lp = $is_submit ? undef : (($first & 0b00001000) >> 3);
my $sr = ($first & 0b00100000) ? 1 : 0;
my $has_udh = ($first & 0b01000000) ? 1 : 0;
my $rp = $is_status ? undef : (($first & 0b10000000) ? 1 : 0);
return unless length $tpdu >= 1;
my $mr = $is_deliver ? undef : ord(substr $tpdu, 0, 1, '');
my ($num, $addr_len) = tpdu_decode_address($tpdu);
return unless defined $num;
substr $tpdu, 0, $addr_len, '';
my ($scts, $dt, $st, $has_pid, $has_dcs, $has_udl);
if ($is_status) {
return unless length $tpdu >= 7+7+1;
$scts = tpdu_decode_ts(substr $tpdu, 0, 7, '');
$dt = tpdu_decode_ts(substr $tpdu, 0, 7, '');
$st = tpdu_decode_st(substr $tpdu, 0, 1, '');
if (length $tpdu >= 1) {
my $pi = ord(substr $tpdu, 0, 1, '');
$has_pid = ($pi & 0b00000001) ? 1 : 0;
$has_dcs = ($pi & 0b00000010) ? 1 : 0;
$has_udl = ($pi & 0b00000100) ? 1 : 0;
my $has_pi_ext = ($pi & 0b10000000) ? 1 : 0;
while ($has_pi_ext) {
return unless length $tpdu >= 1;
$pi = ord(substr $tpdu, 0, 1, '');
$has_pi_ext = ($pi & 0b10000000) ? 1 : 0;
}
}
} else {
$has_pid = $has_dcs = $has_udl = 1;
}
my $pid;
if ($has_pid) {
return unless length $tpdu >= 1;
$pid = ord(substr $tpdu, 0, 1, '');
}
my ($mc, $ad, $mwi, $ud_enc, $ud_cd);
if ($has_dcs) {
return unless length $tpdu >= 1;
($mc, $ad, $mwi, $ud_enc, $ud_cd) = tpdu_decode_dcs(substr $tpdu, 0, 1, '');
}
if ($is_deliver) {
return unless length $tpdu >= 7;
$scts = tpdu_decode_ts(substr $tpdu, 0, 7, '');
}
my $vp;
if (defined $vpf) {
my $vp_len;
($vp, $vp_len) = tpdu_decode_vp($tpdu, $vpf);
return unless defined $vp_len;