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      1 # Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
      2 #
      3 # Licensed under the Apache License 2.0 (the "License").  You may not use
      4 # this file except in compliance with the License.  You can obtain a copy
      5 # in the file LICENSE in the source distribution or at
      6 # https://www.openssl.org/source/license.html
      7 
      8 use strict;
      9 
     10 package TLSProxy::ServerKeyExchange;
     11 
     12 use vars '@ISA';
     13 push @ISA, 'TLSProxy::Message';
     14 
     15 sub new
     16 {
     17     my $class = shift;
     18     my ($server,
     19         $data,
     20         $records,
     21         $startoffset,
     22         $message_frag_lens) = @_;
     23 
     24     my $self = $class->SUPER::new(
     25         $server,
     26         TLSProxy::Message::MT_SERVER_KEY_EXCHANGE,
     27         $data,
     28         $records,
     29         $startoffset,
     30         $message_frag_lens);
     31 
     32     #DHE
     33     $self->{p} = "";
     34     $self->{g} = "";
     35     $self->{pub_key} = "";
     36     $self->{sigalg} = -1;
     37     $self->{sig} = "";
     38 
     39     return $self;
     40 }
     41 
     42 sub parse
     43 {
     44     my $self = shift;
     45     my $sigalg = -1;
     46 
     47     #Minimal SKE parsing. Only supports one known DHE ciphersuite at the moment
     48     return if TLSProxy::Proxy->ciphersuite()
     49                  != TLSProxy::Message::CIPHER_ADH_AES_128_SHA
     50               && TLSProxy::Proxy->ciphersuite()
     51                  != TLSProxy::Message::CIPHER_DHE_RSA_AES_128_SHA;
     52 
     53     my $p_len = unpack('n', $self->data);
     54     my $ptr = 2;
     55     my $p = substr($self->data, $ptr, $p_len);
     56     $ptr += $p_len;
     57 
     58     my $g_len = unpack('n', substr($self->data, $ptr));
     59     $ptr += 2;
     60     my $g = substr($self->data, $ptr, $g_len);
     61     $ptr += $g_len;
     62 
     63     my $pub_key_len = unpack('n', substr($self->data, $ptr));
     64     $ptr += 2;
     65     my $pub_key = substr($self->data, $ptr, $pub_key_len);
     66     $ptr += $pub_key_len;
     67 
     68     #We assume its signed
     69     my $record = ${$self->records}[0];
     70 
     71     if (TLSProxy::Proxy->is_tls13()
     72             || $record->version() == TLSProxy::Record::VERS_TLS_1_2) {
     73         $sigalg = unpack('n', substr($self->data, $ptr));
     74         $ptr += 2;
     75     }
     76     my $sig = "";
     77     if (defined $sigalg) {
     78         my $sig_len = unpack('n', substr($self->data, $ptr));
     79         if (defined $sig_len) {
     80             $ptr += 2;
     81             $sig = substr($self->data, $ptr, $sig_len);
     82             $ptr += $sig_len;
     83         }
     84     }
     85 
     86     $self->p($p);
     87     $self->g($g);
     88     $self->pub_key($pub_key);
     89     $self->sigalg($sigalg) if defined $sigalg;
     90     $self->signature($sig);
     91 }
     92 
     93 
     94 #Reconstruct the on-the-wire message data following changes
     95 sub set_message_contents
     96 {
     97     my $self = shift;
     98     my $data;
     99 
    100     $data = pack('n', length($self->p));
    101     $data .= $self->p;
    102     $data .= pack('n', length($self->g));
    103     $data .= $self->g;
    104     $data .= pack('n', length($self->pub_key));
    105     $data .= $self->pub_key;
    106     $data .= pack('n', $self->sigalg) if ($self->sigalg != -1);
    107     if (length($self->signature) > 0) {
    108         $data .= pack('n', length($self->signature));
    109         $data .= $self->signature;
    110     }
    111 
    112     $self->data($data);
    113 }
    114 
    115 #Read/write accessors
    116 #DHE
    117 sub p
    118 {
    119     my $self = shift;
    120     if (@_) {
    121       $self->{p} = shift;
    122     }
    123     return $self->{p};
    124 }
    125 sub g
    126 {
    127     my $self = shift;
    128     if (@_) {
    129       $self->{g} = shift;
    130     }
    131     return $self->{g};
    132 }
    133 sub pub_key
    134 {
    135     my $self = shift;
    136     if (@_) {
    137       $self->{pub_key} = shift;
    138     }
    139     return $self->{pub_key};
    140 }
    141 sub sigalg
    142 {
    143     my $self = shift;
    144     if (@_) {
    145       $self->{sigalg} = shift;
    146     }
    147     return $self->{sigalg};
    148 }
    149 sub signature
    150 {
    151     my $self = shift;
    152     if (@_) {
    153       $self->{sig} = shift;
    154     }
    155     return $self->{sig};
    156 }
    157 1;
    158