adding srtp support to simulator script

tests/simulator-ng.pl

@@ -9,6 +9,9 @@ use Getopt::Long;
 use Socket6;
 use Bencode qw( bencode bdecode );
 use Time::HiRes;
+use Crypt::Rijndael;
+use Digest::SHA qw(hmac_sha1);
+use MIME::Base64;
 
 my ($NUM, $RUNTIME, $STREAMS) = (1000, 30, 1);
 my ($NODEL, $IP, $IPV6, $KEEPGOING, $REINVITES, $BRANCHES);
@@ -29,6 +32,14 @@ GetOptions(
 $SIG{ALRM} = sub { print "alarm!\n"; };
 setrlimit(RLIMIT_NOFILE, 8000, 8000);
 
+# global for now
+#my $srtp_master_key = pack("H*", 'E1F97A0D3E018BE0D64FA32C06DE4139');
+#my $srtp_master_salt = pack("H*", '0EC675AD498AFEEBB6960B3AABE6');
+#my ($srtp_session_key, $srtp_session_auth_key, $srtp_session_salt)
+#	= gen_rtp_session_keys($srtp_master_key, $srtp_master_salt);
+#my ($srtcp_session_key, $srtcp_session_auth_key, $srtcp_session_salt)
+#	= gen_rtcp_session_keys($srtp_master_key, $srtp_master_salt);
+
 my @chrs = ('a' .. 'z', 'A' .. 'Z', '0' .. '9');
 sub rand_str {
 	my ($len) = @_;
@@ -76,21 +87,160 @@ sub send_receive {
 	return $x;
 }
 
-sub send_expect {
-	my ($send_fd, $receive_fd, $payload, $expect, $destination) = @_;
+sub aes_cm {
+	my ($data, $key, $iv) = @_;
+
+	my $c = Crypt::Rijndael->new($key) or die;
+	length($iv) == 16 or die;
+	my @iv = unpack("C16", $iv);
+	my $out = '';
+
+	while ($data ne '') {
+		$iv = pack("C16", @iv);
+		my $key_segment = $c->encrypt($iv);
+		length($key_segment) == 16 or die;
+		my @ks = unpack("C16", $key_segment);
+		my @ds = unpack("C16", $data);
+
+		for my $i (0 .. $#ds) {
+			my $ss = $ds[$i];
+			my $kk = $ks[$i];
+			$out .= chr($ss ^ $kk);
+		}
+
+		substr($data, 0, 16, '');
+		$data eq '' and last;
 
-	my $x = send_receive($send_fd, $receive_fd, $payload, $destination);
-	if (($x || '') ne $expect) {
-		return 0;
+		for my $i (reverse(0 .. 15)) {
+			$iv[$i]++;
+			if ($iv[$i] == 256) {
+				$iv[$i] = 0;
+			}
+			else {
+				last;
+			}
+		}
 	}
-	return 1;
+
+	return $out;
+}
+
+sub prf_n {
+	my ($n, $key, $x) = @_;
+	my $d = "\0" x ($n / 8);
+	my $ks = aes_cm($d, $key, $x . "\0\0");
+	return substr($ks, 0, $n / 8);
+}
+
+sub xor_n {
+	my ($n, @l) = @_;
+	$n /= 8;
+	my @o = (0) x $n;
+	for my $e (@l) {
+		my @e = unpack("C$n", $e);
+		if (@e < $n) {
+			unshift(@e, ((0) x ($n - @e)));
+		}
+		for my $i (0 .. $#o) {
+			$o[$i] ^= $e[$i];
+		}
+	}
+	return pack("C$n", @o);
+}
+
+sub xor_112 {
+	return xor_n(112, @_);
+}
+sub xor_128 {
+	return xor_n(128, @_);
+}
+
+sub gen_rtp_session_keys {
+	my ($master_key, $master_salt) = @_;
+
+	my $session_key = prf_n(128, $master_key, xor_112($master_salt, "\0\0\0\0\0\0\0"));
+	my $auth_key = prf_n(160, $master_key, xor_112($master_salt, "\1\0\0\0\0\0\0"));
+	my $session_salt = prf_n(112, $master_key, xor_112($master_salt, "\2\0\0\0\0\0\0"));
+
+	return ($session_key, $auth_key, $session_salt);
+}
+
+sub gen_rtcp_session_keys {
+	my ($master_key, $master_salt) = @_;
+
+	my $session_key = prf_n(128, $master_key, xor_112($master_salt, "\3\0\0\0\0"));
+	my $auth_key = prf_n(160, $master_key, xor_112($master_salt, "\4\0\0\0\0"));
+	my $session_salt = prf_n(112, $master_key, xor_112($master_salt, "\5\0\0\0\0"));
+
+	return ($session_key, $auth_key, $session_salt);
+}
+
+sub rtcp_encrypt {
+	my ($r, $ctx, $dir) = @_;
+
+	if (!$$ctx{rtcp_session_key}) {
+		($$ctx{$dir}{rtcp_session_key}, $$ctx{$dir}{rtcp_session_auth_key}, $$ctx{$dir}{rtcp_session_salt})
+			= gen_rtp_session_keys($$ctx{$dir}{rtp_master_key}, $$ctx{$dir}{rtp_master_salt});
+	}
+
+	my $idx = $$ctx{$dir}{rtcp_index} || 0;
+	my ($hdr, $ssrc, $to_enc) = unpack('a4a4a*', $r);
+	my $iv = xor_128($$ctx{$dir}{rtcp_session_salt} . "\0\0",
+		$ssrc . "\0\0\0\0\0\0\0\0", pack("Nn", $idx, 0));
+	my $enc = aes_cm($to_enc, $$ctx{$dir}{rtcp_session_key}, $iv);
+	my $pkt = $hdr . $ssrc . $enc;
+	$pkt .= pack("N", ($idx | 0x80000000));
+
+	my $hmac = hmac_sha1($pkt, $$ctx{$dir}{rtcp_session_auth_key});
+
+	#$pkt .= pack("N", 1); # mki
+	$pkt .= substr($hmac, 0, 10);
+
+	$$ctx{$dir}{rtcp_index} = ++$idx;
+
+	return $pkt;
+}
+
+sub rtp_encrypt {
+	my ($r, $ctx, $dir) = @_;
+
+	if (!$$ctx{$dir}{rtp_session_key}) {
+		($$ctx{$dir}{rtp_session_key}, $$ctx{$dir}{rtp_session_auth_key}, $$ctx{$dir}{rtp_session_salt})
+			= gen_rtp_session_keys($$ctx{$dir}{rtp_master_key}, $$ctx{$dir}{rtp_master_salt});
+	}
+
+	my $roc = $$ctx{$dir}{rtp_roc} || 0;
+	my ($hdr, $seq, $ts, $ssrc, $to_enc) = unpack('a2na4a4a*', $r);
+	$seq == 0 and $roc++;
+	my $iv = xor_128($$ctx{$dir}{rtp_session_salt} . "\0\0",
+		$ssrc . "\0\0\0\0\0\0\0\0", pack("Nnn", $roc, $seq, 0));
+	my $enc = aes_cm($to_enc, $$ctx{$dir}{rtp_session_key}, $iv);
+	my $pkt = pack("a*na*a*a*", $hdr, $seq, $ts, $ssrc, $enc);
+
+	my $hmac = hmac_sha1($pkt . pack("N", $roc), $$ctx{$dir}{rtp_session_auth_key});
+
+	#$pkt .= pack("N", 1); # mki
+	$pkt .= substr($hmac, 0, 10);
+
+	$$ctx{$dir}{rtp_roc} = $roc;
+
+	return $pkt;
+}
+
+sub savp_sdp {
+	my ($ctx) = @_;
+	if (!$$ctx{out}{rtp_master_key}) {
+		$$ctx{out}{rtp_master_key} = rand_str(16);
+		$$ctx{out}{rtp_master_salt} = rand_str(14);
+	}
+	return "a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:" . encode_base64($$ctx{out}{rtp_master_key} . $$ctx{out}{rtp_master_salt}, '') . "\n";
 }
 
 sub rtcp_sr {
 	my @now = Time::HiRes::gettimeofday();
 	my $secs = $now[0] + 2208988800;
 	my $frac = $now[1] / 1000000 * 2**32;
-	my $sr = pack('CCnN NNN NN', (2 << 6) | 1, 200, 12, rand() * 2**32, $secs, $frac,
+	my $sr = pack('CCnN NNN NN', (2 << 6) | 1, 200, 12, rand(2**32), $secs, $frac,
 		12345, 0, 0);
 	$sr .= pack('N CCCC NNNN', 0, 0, 0, 0, 0, 0, 0, 0, 0);
 	return $sr;
@@ -101,13 +251,24 @@ sub rtcp_rtpfb {
 }
 
 sub rtcp_avp {
-	my ($recv, $send) = @_;
+	my ($recv, $ctx, $ctx_o) = @_;
+	my $sr = rtcp_sr();
+	my $exp = $sr;
+	$$recv{name} eq 'RTP/SAVP' and $exp = rtcp_encrypt($sr, $ctx_o, 'in');
+	return ($sr, $exp);
+}
+
+sub rtcp_savp {
+	my ($recv, $ctx, $ctx_o) = @_;
 	my $sr = rtcp_sr();
-	return ($sr, $sr);
+	my $enc = rtcp_encrypt($sr, $ctx, 'out');
+	my $exp = $enc;
+	$$recv{name} eq 'RTP/AVP' and $exp = $sr;
+	return ($enc, $exp);
 }
 
 sub rtcp_avpf {
-	my ($recv, $send) = @_;
+	my ($recv, $ctx, $ctx_o) = @_;
 	my $sr = rtcp_sr();
 	my $fb = rtcp_rtpfb();
 	my $exp = $sr;
@@ -115,28 +276,78 @@ sub rtcp_avpf {
 	return ($sr . $fb, $exp);
 }
 
+sub rtp {
+	my ($ctx) = @_;
+	my $seq = $$ctx{rtp_seqnum} || (int(rand(0xfffff)) + 1);
+	my $hdr = pack("CCnNN", 0x80, 0x00, $seq, rand(2**32), rand(2**32));
+	my $pack = $hdr . rand_str(100);
+	$$ctx{rtp_seqnum} = (++$seq & 0xffff);
+	return $pack;
+}
+
+sub rtp_avp {
+	my ($recv, $ctx, $ctx_o) = @_;
+	my $pack = rtp($ctx);
+	my $exp = $pack;
+	$$recv{name} eq 'RTP/SAVP' and $exp = rtp_encrypt($pack, $ctx_o, 'in');
+	return ($pack, $exp);
+}
+
+sub rtp_savp {
+	my ($recv, $ctx, $ctx_o) = @_;
+	my $pack = rtp($ctx);
+	my $enc = rtp_encrypt($pack, $ctx, 'out');
+	my $exp = $enc;
+	$$recv{name} eq 'RTP/AVP' and $exp = $pack;
+	return ($enc, $exp);
+}
+
+sub savp_crypto {
+	my ($sdp, $ctx) = @_;
+
+	my @a = $sdp =~ /[\r\n]a=crypto:1 AES_CM_128_HMAC_SHA1_80 inline:([\w\/+]{40})(?:\|(?:2\^(\d+)|(\d+)))?(?:\|(\d+):(\d+))?[\r\n]/si;
+	@a or die;
+	my $ks = decode_base64($a[0]);
+	length($ks) == 30 or die;
+	($$ctx{in}{rtp_master_key}, $$ctx{in}{rtp_master_salt}) = unpack('a16a14', $ks);
+	$$ctx{in}{rtp_mki} = $a[3];
+	$$ctx{in}{rtp_mki_len} = $a[4];
+}
+
+sub hexdump {
+	my $o = '';
+	for my $a (@_) {
+		$o .= "<< " . unpack("H*", $a) . " >> ";
+	}
+	return $o;
+}
+
 sub do_rtp {
 	print("sending rtp\n");
 	for my $c (@calls) {
 		$c or next;
-		my ($fds,$outputs,$protos,$cfds,$trans) = @$c{qw(fds outputs protos rtcp_fds transports)};
+		my ($fds,$outputs,$protos,$cfds,$trans,$tctxs)
+			= @$c{qw(fds outputs protos rtcp_fds transports trans_contexts)};
 		for my $j (0 .. $#{$$fds[0]}) {
 			for my $i ([0,1],[1,0]) {
 				my ($a, $b) = @$i;
 				my $pr = $$protos[$a];
+				my $tcx = $$tctxs[$a];
+				my $tcx_o = $$tctxs[$b];
 				my $addr = inet_pton($$pr{family}, $$outputs[$b][$j][1]);
-				my $payload = rand_str(100);
+				my ($payload, $expect) = $$trans[$a]{rtp_func}($$trans[$b], $tcx, $tcx_o);
 				my $dst = $$pr{sockaddr}($$outputs[$b][$j][0], $addr);
-				if (!send_expect($$fds[$a][$j], $$fds[$b][$j], $payload, $payload, $dst)) {
+				my $repl = send_receive($$fds[$a][$j], $$fds[$b][$j], $payload, $dst);
+				if ($repl eq '') {
 					warn("no rtp reply received, ports $$outputs[$b][$j][0] and $$outputs[$a][$j][0]");
 					$KEEPGOING or undef($c);
 				}
+				$repl eq $expect or die hexdump($repl, $expect);
 
-				my $expect;
-				($payload, $expect) = $$trans[$a]{rtcp_func}($$trans[$b], $$trans[$a]);
+				($payload, $expect) = $$trans[$a]{rtcp_func}($$trans[$b], $tcx, $tcx_o);
 				$dst = $$pr{sockaddr}($$outputs[$b][$j][0] + 1, $addr);
-				my $repl = send_receive($$cfds[$a][$j], $$cfds[$b][$j], $payload, $dst);
-				$repl eq $expect or die;
+				$repl = send_receive($$cfds[$a][$j], $$cfds[$b][$j], $payload, $dst);
+				$repl eq $expect or die hexdump($repl, $expect);
 			}
 		}
 	}
@@ -170,11 +381,20 @@ my @sides = qw(A B);
 my @transports = (
 	{
 		name => 'RTP/AVP',
+		rtp_func => \&rtp_avp,
 		rtcp_func => \&rtcp_avp,
 	},
+#	{
+#		name => 'RTP/AVPF',
+#		rtp_func => &rtp_avpf,
+#		rtcp_func => \&rtcp_avpf,
+#	},
 	{
-		name => 'RTP/AVPF',
-		rtcp_func => \&rtcp_avpf,
+		name => 'RTP/SAVP',
+		sdp_media_params => \&savp_sdp,
+		sdp_parse_func => \&savp_crypto,
+		rtp_func => \&rtp_savp,
+		rtcp_func => \&rtcp_savp,
 	},
 );
 
@@ -200,6 +420,7 @@ sub update_lookup {
 
 	my $protos = $$c{protos} || ($$c{protos} = []);
 	my $trans = $$c{transports} || ($$c{transports} = []);
+	my $tctxs = $$c{trans_contexts} || ($$c{trans_contexts} = []);
 	my $fds_a = $$c{fds} || ($$c{fds} = []);
 	my $cfds_a = $$c{rtcp_fds} || ($$c{rtcp_fds} = []);
 	for my $x (0,1) {
@@ -214,6 +435,8 @@ sub update_lookup {
 	}
 	my ($pr, $pr_o) = @$protos[$i, $j];
 	my ($tr, $tr_o) = @$trans[$i, $j];
+	my $tcx = $$tctxs[$i] || ($$tctxs[$i] = {});
+	my $tcx_o = $$tctxs[$j] || ($$tctxs[$j] = {});
 	my @commands = qw(offer answer);
 
 	my $ports_a = $$c{ports} || ($$c{ports} = []);
@@ -264,7 +487,9 @@ m=audio $p $$tr{name} 8
 a=rtpmap:8 PCMA/8000
 a=rtcp:$cp
 !
+		$$tr{sdp_media_params} and $sdp .= $$tr{sdp_media_params}($tcx);
 	}
+	print("transport is $$tr{name} -> $$tr_o{name}\n"); # XXX
 
 	my $dict = {sdp => $sdp, command => $commands[$i], 'call-id' => $callid,
 		'from-tag' => $$tags[0],
@@ -278,6 +503,7 @@ a=rtcp:$cp
 	$i == 1 and $dict->{'to-tag'} = $$tags[1];
 
 	my $o = msg($dict);
+
 	$$o{result} eq 'ok' or die;
 	my ($rp_af, $rp_add) = $$o{sdp} =~ /c=IN IP([46]) (\S+)/s or die;
 	my @rp_ports = $$o{sdp} =~ /m=audio (\d+) \Q$$tr_o{name}\E /gs or die;
@@ -288,6 +514,7 @@ a=rtcp:$cp
 		$rpl == 0 and die "mediaproxy ran out of ports";
 		push(@$rpl_t, [$rpl,$rp_add]);
 	}
+	$$tr_o{sdp_parse_func} and $$tr_o{sdp_parse_func}($$o{sdp}, $tcx_o);
 }
 
 for my $iter (1 .. $NUM) {