More tests of FALLBACK_SCSV
This is a backport of a non-regression test for issue #810 which affected
the current release of mbed TLS, but not the 1.3 branch.
diff --git a/tests/scripts/tcp_client.pl b/tests/scripts/tcp_client.pl
new file mode 100755
index 0000000..11cbf1b
--- /dev/null
+++ b/tests/scripts/tcp_client.pl
@@ -0,0 +1,86 @@
+#!/usr/bin/env perl
+
+# A simple TCP client that sends some data and expects a response.
+# Usage: tcp_client.pl HOSTNAME PORT DATA1 RESPONSE1
+# DATA: hex-encoded data to send to the server
+# RESPONSE: regexp that must match the server's response
+
+use warnings;
+use strict;
+use IO::Socket::INET;
+
+# Pack hex digits into a binary string, ignoring whitespace.
+sub parse_hex {
+ my ($hex) = @_;
+ $hex =~ s/\s+//g;
+ return pack('H*', $hex);
+}
+
+## Open a TCP connection to the specified host and port.
+sub open_connection {
+ my ($host, $port) = @_;
+ my $socket = IO::Socket::INET->new(PeerAddr => $host,
+ PeerPort => $port,
+ Proto => 'tcp',
+ Timeout => 1);
+ die "Cannot connect to $host:$port: $!" unless $socket;
+ return $socket;
+}
+
+## Close the TCP connection.
+sub close_connection {
+ my ($connection) = @_;
+ $connection->shutdown(2);
+ # Ignore shutdown failures (at least for now)
+ return 1;
+}
+
+## Write the given data, expressed as hexadecimal
+sub write_data {
+ my ($connection, $hexdata) = @_;
+ my $data = parse_hex($hexdata);
+ my $total_sent = 0;
+ while ($total_sent < length($data)) {
+ my $sent = $connection->send($data, 0);
+ if (!defined $sent) {
+ die "Unable to send data: $!";
+ }
+ $total_sent += $sent;
+ }
+ return 1;
+}
+
+## Read a response and check it against an expected prefix
+sub read_response {
+ my ($connection, $expected_hex) = @_;
+ my $expected_data = parse_hex($expected_hex);
+ my $start_offset = 0;
+ while ($start_offset < length($expected_data)) {
+ my $actual_data;
+ my $ok = $connection->recv($actual_data, length($expected_data));
+ if (!defined $ok) {
+ die "Unable to receive data: $!";
+ }
+ if (($actual_data ^ substr($expected_data, $start_offset)) =~ /[^\000]/) {
+ printf STDERR ("Received \\x%02x instead of \\x%02x at offset %d\n",
+ ord(substr($actual_data, $-[0], 1)),
+ ord(substr($expected_data, $start_offset + $-[0], 1)),
+ $start_offset + $-[0]);
+ return 0;
+ }
+ $start_offset += length($actual_data);
+ }
+ return 1;
+}
+
+if (@ARGV != 4) {
+ print STDERR "Usage: $0 HOSTNAME PORT DATA1 RESPONSE1\n";
+ exit(3);
+}
+my ($host, $port, $data1, $response1) = @ARGV;
+my $connection = open_connection($host, $port);
+write_data($connection, $data1);
+if (!read_response($connection, $response1)) {
+ exit(1);
+}
+close_connection($connection);