# Copyright 2016-2019 The OpenSSL Project Authors. All Rights Reserved.

#

# Licensed under the OpenSSL license (the "License").  You may not use

# this file except in compliance with the License.  You can obtain a copy

# in the file LICENSE in the source distribution or at

# https://www.openssl.org/source/license.html

use strict;

package TLSProxy::ServerKeyExchange;

use vars '@ISA';

push @ISA, 'TLSProxy::Message';

sub new

{

    my $class = shift;

    my ($server,

        $data,

        $records,

        $startoffset,

        $message_frag_lens) = @_;

    my $self = $class->SUPER::new(

        $server,

        TLSProxy::Message::MT_SERVER_KEY_EXCHANGE,

        $data,

        $records,

        $startoffset,

        $message_frag_lens);

    #DHE

    $self->{p} = "";

    $self->{g} = "";

    $self->{pub_key} = "";

    $self->{sigalg} = -1;

    $self->{sig} = "";

    return $self;

}

sub parse

{

    my $self = shift;

    my $sigalg = -1;

    #Minimal SKE parsing. Only supports one known DHE ciphersuite at the moment

    return if TLSProxy::Proxy->ciphersuite()

                 != TLSProxy::Message::CIPHER_ADH_AES_128_SHA

              && TLSProxy::Proxy->ciphersuite()

                 != TLSProxy::Message::CIPHER_DHE_RSA_AES_128_SHA;

    my $p_len = unpack('n', $self->data);

    my $ptr = 2;

    my $p = substr($self->data, $ptr, $p_len);

    $ptr += $p_len;

    my $g_len = unpack('n', substr($self->data, $ptr));

    $ptr += 2;

    my $g = substr($self->data, $ptr, $g_len);

    $ptr += $g_len;

    my $pub_key_len = unpack('n', substr($self->data, $ptr));

    $ptr += 2;

    my $pub_key = substr($self->data, $ptr, $pub_key_len);

    $ptr += $pub_key_len;

    #We assume its signed

    my $record = ${$self->records}[0];

    if (TLSProxy::Proxy->is_tls13()

            || $record->version() == TLSProxy::Record::VERS_TLS_1_2) {

        $sigalg = unpack('n', substr($self->data, $ptr));

        $ptr += 2;

    }

    my $sig = "";

    if (defined $sigalg) {

        my $sig_len = unpack('n', substr($self->data, $ptr));

        if (defined $sig_len) {

            $ptr += 2;

            $sig = substr($self->data, $ptr, $sig_len);

            $ptr += $sig_len;

        }

    }

    $self->p($p);

    $self->g($g);

    $self->pub_key($pub_key);

    $self->sigalg($sigalg) if defined $sigalg;

    $self->signature($sig);

}

#Reconstruct the on-the-wire message data following changes

sub set_message_contents

{

    my $self = shift;

    my $data;

    $data = pack('n', length($self->p));

    $data .= $self->p;

    $data .= pack('n', length($self->g));

    $data .= $self->g;

    $data .= pack('n', length($self->pub_key));

    $data .= $self->pub_key;

    $data .= pack('n', $self->sigalg) if ($self->sigalg != -1);

    if (length($self->signature) > 0) {

        $data .= pack('n', length($self->signature));

        $data .= $self->signature;

    }

    $self->data($data);

}

#Read/write accessors

#DHE

sub p

{

    my $self = shift;

    if (@_) {

      $self->{p} = shift;

    }

    return $self->{p};

}

sub g

{

    my $self = shift;

    if (@_) {

      $self->{g} = shift;

    }

    return $self->{g};

}

sub pub_key

{

    my $self = shift;

    if (@_) {

      $self->{pub_key} = shift;

    }

    return $self->{pub_key};

}

sub sigalg

{

    my $self = shift;

    if (@_) {

      $self->{sigalg} = shift;

    }

    return $self->{sigalg};

}

sub signature

{

    my $self = shift;

    if (@_) {

      $self->{sig} = shift;

    }

    return $self->{sig};

}

1;