IMS测试中ENUM模拟软件

ENUM 遵循 DNS 协议。ENUM是IETF的电话号码映射工作组定义的一个协议——RFC2916，RFC2916的题目为“E.164号码和域名系统”。它定义了将E.164号码转换为域名形式放在DNS服务器数据库中的方法，每个由E.164号码转化而成的域名可以对应一系列的统一资源辨识URI，从而使国际统一的E.164电话号码成为可以在互联网中使用的网络地址资源。

根据ENUM格式的定义，将电话号码变成了DNS中的域名形式。每个E.164号码形成的域名可以对应多条网络资源记录，称为统一资源标志URI，它是采用另一个IETF建议RFC2915定义的格式，称为“名称权威指针”（NAPTR）。

在IMS测试中，需要用到ENUM服务器，一般用bind来替代，需要配置各种号码。下面是一个模拟器，可以很方便的完成一些简单功能，而避开用真正的ENUM

#!/usr/bin/perl

use strict;
use IO::Socket::INET;
use POSIX 'WNOHANG';
use Getopt::Long;

use constant PORT   => 53;
use constant SUFFIX => '.e164.arpa';
use constant REALM  => 'qd.lucentlab.com';
use constant USAGE  => <<USE;

    This is a ENUM simulator, only supports 2 response messages now
    1. Query success with one record
    2. Query failed with "No such Name"
    Usage:
        $0 --port port --prefix prefix --suffix suffix --realm realm[--debug]

    port     Default port is 53
    prefix   Reponse message type 1 for DNs with this prefix
             Other DN will response with type 2
    suffix   The suffix of query message, Default is '.e164.arpa'
    realm    The SIPURI domain/realm, default is 'qd.lucent.com'
    debug    Show more debug message

    Example:
        $0 --prefix 1543 --debug
        $0 --prefix 1543 --suffix '.e164.cn'

    Contact: Tristan Yu (tyu@)

USE

my ($port, $prefix, $suffix, $realm, $debug, $help);
my $file;

err_exit(USAGE, 255) unless GetOptions( 
            'port=s'   => \$port, 'prefix=s' => \$prefix, 'suffix=s' => \$suffix,
            'realm=s'  => \$realm, 'debug'    => \$debug, 'help'     => \$help, 
            'file=s'   => \$file      );

if ($help) {
    print USAGE;
    exit 0;
}

if ( $file ) {
    eval(require $file) || die "$file format is wrong, check the program help";
}
$port   ||= PORT;
$suffix ||= SUFFIX;
$realm  ||= REALM;

err_exit("\tPort should be digits", 1) unless $port =~ /^\d+$/;
err_exit("\tMust have a prefix", 1) if ($prefix eq "");

if ($debug) {
    print "Configuration data:\n";
    print "Port: $port, Prefix: $prefix, Suffix: $suffix, Realm: $realm, Debug: $debug\n";
}

# MAIN STARTS HERE #

$| = 1;
$/ = '\012\015';

my $ok_prefix = $prefix;
my $count  = 0;

$SIG{INT}  = sub { print "Totally processed $count ENUM queries\n"; exit 0 };
$SIG{ALRM} = sub { print "X\n";};
$SIG{CHLD} = sub { while ( waitpid(-1, WNOHANG)>0 ) {}};

#Do not change any value below in the while loop
#Variables for ENUM message header

my $corrid = 1; # 16-bit field, used to correlate queries and responses. 
my $qr     = 1; # 1-bit field, that identifies the message as a response. 
my $opcode = 0; # 4bits field to indicate the operation. 0 means QUERY, Standard query
my $aa     = 1; # 1-bit field, Authoritative Answer, 1 means "Not authoritative."
my $tc     = 0; # 1-bit field, Truncation, 0 means Not truncated.
my $rd     = 1; # 1-bit field, Recursion Desired
my $ra     = 1; # 1-bit field, Recursion Available
my $ad     = 0; # 1-bit field, Authenticated data 
my $cd     = 0;
my $z      = 0; # Must be 0 for NOW (RFC1035)
my $rcode  = 0; # 4-bit field, Response Code, is set by the NS to identify the status of the query

# 16-bit field that defines the number of entries in the question section
my $ques = 1; 
# 16-bit field that defines the number of resource records in the answer section. 
my $answ = 1; 
# 16-bit field that defines the number of name server resource records in the authority section
my $auth = 1; 
# 16-bit field that defines the number of resource records in the additional records section.
my $addt = 0; 

my $byte1  = (($qr?0x80:0)|($opcode << 3)|($aa?0x04:0)|($tc?0x02:0)|($rd?0x01:0));
# Response with resualt
my $byte2  = (($ra?0x80:0)|($ad?0x20:0)|($cd?0x10:0)|($rcode));
# Response with "No Such Name"
my $byte2_f  = (($ra?0x80:0)|($ad?0x20:0)|($cd?0x10:0)|(0x3));

my $header_fix_ok = pack("C2 n4", $byte1, $byte2, $ques, $answ, $auth, $addt);
my $header_fix_nf = pack("C2 n4", $byte1, $byte2_f, $ques, 0, $auth, $addt);

#Variables for ENUM message answer
my $dname = 0xC000; #Indicator this is a pointer
my $type  = 35; # NAPTR, Naming Authority Pointer.
my $class = 1;  # IN, Internet.
my $ttl   = 0;
my $order = 100;
my $pref  = 100;
# "u" flag means that the next step is not a DNS lookup but that the output 
# of the Regexp field is an URI that adheres to the 'absoluteURI' product
my $flag  = "u"; 
my $serv  = 'E2U+sip';

#Variables for ENUM message authorize
my $aname = 0xC000; #Indicator this is a pointer
my $atype = 2;      #A NS record for the domain name
my $attl  = 3600 * 24; # 24 hours
my $ns    = dns_normalize($realm);

my $auth_pre_data = pack("n2 L n", $atype, $class, $attl, length($ns)) . $ns;

use constant HEADER_LENGTH   => length pack 'n C2 n4', (0)x7;
use constant QUESTION_LENGTH => length pack 'n2', (0)x2;

# Setup Socket
my $enum_server = IO::Socket::INET->new(
        #LocalAddr => '135.252.29.135',
        LocalPort => $port,
        Proto     => 'udp',
        ) or die "Could not open UPD port 53 $!";
binmode $enum_server;

print "UDP ENUM server is running ...\n";
while (1) {
    my $data_buf;
    next unless my $peer_addr = $enum_server->recv($data_buf, 1024);
    defined ( my $enum_s = fork())
        or do { print "\nFork an ENUM processor failed\n", next;};

    if ($enum_s == 0) {
        if ($debug) {
            my ($portno, $ipaddr) = sockaddr_in($peer_addr);
            print "Host " . inet_ntoa($ipaddr) . ":" . $portno ;
        }
        alarm(1);
        my $corrid = unpack('n', $data_buf);

        my ($qname, $offset) = parse_question(\$data_buf, HEADER_LENGTH);
        print "\nQuery for $qname [$corrid]\n" if $debug;
        #Generate query with query name
        my $query_data = dns_normalize($qname) . pack("n2", $type, $class);

        my $e164_num   = to_e164($qname);
        print "E164 is $e164_num\n" if $debug;
        my $dname_ptr  = HEADER_LENGTH;
        my $aname_ptr  = $dname_ptr + 2 * length($e164_num);

        my $header_data = "";
        my $answer_data = "";

        if ($e164_num =~ /^$ok_prefix/) {
            print "Query successfully response \n" if $debug;
            #Generate header with the corrilation identity
            $header_data = pack("n", $corrid) . $header_fix_ok;

            #Generate the DNS regular expression
            my $regex = '!^.*$!sip:+' . $e164_num . '@' . $realm . '!';
            my $relen = length($regex); # The length of the regex
            my $rdata = pack("n2 C a C a7 C a$relen C",
                            $order, $pref, length($flag), $flag, length($serv), $serv, $relen, $regex, 0) ;
            $answer_data = pack("n", ($dname|$dname_ptr))
                        . pack("n2 L n", $type, $class, $ttl, length($rdata)) . $rdata;
        } else {
            print "Query No such Name response \n" if $debug;
            #Response with No such Name
            $answer_data = ""; 
            $header_data = pack("n", $corrid) . $header_fix_nf;
        }

        my $auth_data = pack("n", ($aname|$aname_ptr)) . $auth_pre_data;

        $enum_server->send($header_data.$query_data.$answer_data.$auth_data);

        alarm(0);

        print "Done for $qname\n" if $debug;
        print "." if not $debug;
        exit 0;
    }

    $count++;
    print "\b" x 80 if ( not $debug and ($count % 80 == 0));
}

sub dns_normalize {
    my ($i) = @_;
    my @ele = split /\./, $i;
    my $message = "";
    foreach my $e (@ele) {
        $message .= pack("C a*", length($e), $e);
    }
    $message .= pack("C", 0);
    return $message;
}

# Function to parse e164 number

sub to_e164 {
    my ($var) = @_;
    $var =~ s/$suffix//g;
    $var =~ s/\.$//o;
    my $e164_num = join("", reverse(split /\./, $var));
    return $e164_num;
}

# Function to parse the incoming message

sub parse_question {
    my ($packet, $offset) = @_;
    my $packetlen = length($$packet);
    my $name = '';

    while ( $offset < $packetlen ) {
        unless ( my $length = unpack("\@$offset C", $$packet) ) {
            $name =~ s/\.$//o;
            return ($name, ++$offset);
        } else {
            my $element = substr($$packet, ++$offset, $length);
            $name .= $element.'.';
            $offset += $length;
        }
    }
    return undef;
}

sub err_exit {
    my ($err_msg ,$err_no) = @_;
    print $err_msg, "\n";
    exit $err_no;
}