###########################################################################
# package Net::SIP::Leg
# a leg is a special kind of socket, which can send and receive SIP packets
# and manipulate transport relevant SIP header (Via,Record-Route)
###########################################################################
use strict;
use warnings;
package Net::SIP::Leg;
use Digest::MD5 'md5_hex';
use Socket;
use Net::SIP::Debug;
use Net::SIP::Util qw( sip_hdrval2parts invoke_callback sip_uri_eq );
use Net::SIP::Packet;
use Net::SIP::Request;
use Net::SIP::Response;
use Errno 'EHOSTUNREACH';
use fields qw( sock addr port proto contact branch via );
# sock: the socket for the leg
# addr,port: addr,port where it listens
# proto: udp|tcp
# contact: to identify myself (default from addr:port)
# branch: base for branch-tag for via header
# via: precomputed part of via value
###########################################################################
# create a new leg
# Args: ($class,%args)
# %args: hash, the following keys will be used and deleted from hash
# sock: socket, the addr,port and proto will be determined from this
# addr,port,proto: if sock is not given they will be used to
# create a socket. port defaults to 5060 and proto to udp
# if port is defined and 0 a port will be assigned from the system
# proto: defaults to udp
# contact: default based on addr and port
# branch: if not given will be created
# Returns: $self
###########################################################################
sub new {
my ($class,%args) = @_;
my $self = fields::new($class);
if ( my $addr = delete $args{addr} ) {
my $port = delete $args{port};
# port = 0 -> get port from system
if ( ! defined $port ) {
$port = $1 if $addr =~s{:(\d+)$}{};
$port ||= 5060;
}
my $proto = $self->{proto} = delete $args{proto} || 'udp';
if ( ! ( $self->{sock} = delete $args{sock} ) ) {
$self->{sock} = IO::Socket::INET->new(
Proto => $proto,
LocalPort => $port,
LocalAddr => $addr,
) || die "failed $proto $addr:$port $!";
}
if ( ! $port ) {
# get the assigned port
($port) = unpack_sockaddr_in( getsockname( $self->{sock} ));
}
$self->{port} = $port;
$self->{addr} = $addr;
} elsif ( my $sock = $self->{sock} = delete $args{sock} ) {
# get data from socket
($self->{port}, my $addr) = unpack_sockaddr_in( $sock->sockname );
$self->{addr} = inet_ntoa( $addr );
$self->{proto} = ( $sock->socktype == SOCK_STREAM ) ? 'tcp':'udp'
}
my ($port,$sip_proto) =
$self->{port} == 5060 ? ( '','sip' ) :
( $self->{port} == 5061 and $self->{proto} eq 'tcp' ) ? ( '','sips' ) :
( ":$self->{port}",'sip' )
;
my $leg_addr = $self->{addr}.$port;
$self->{contact} = delete $args{contact} || "$sip_proto:$leg_addr";
$self->{branch} = 'z9hG4bK'.
( delete $args{branch} || md5_hex( @{$self}{qw( addr port proto )} ));
$self->{contact} =~m{^\w+:(.*)};
$self->{via} = sprintf( "SIP/2.0/%s %s;branch=",
uc($self->{proto}),$leg_addr );
return $self;
}
###########################################################################
# prepare incoming packet for forwarding
# Args: ($self,$packet)
# $packet: incoming Net::SIP::Packet, gets modified in-place
# Returns: undef | [code,text]
# code: error code (can be empty if just drop packet on error)
# text: error description (e.g max-forwards reached..)
###########################################################################
sub forward_incoming {
my Net::SIP::Leg $self = shift;
my ($packet) = @_;
if ( $packet->is_response ) {
# remove top via
my $via;
$packet->scan_header( via => [ sub {
my ($vref,$hdr) = @_;
if ( !$$vref ) {
$$vref = $hdr->{value};
$hdr->remove;
}
}, \$via ]);
} else {
# Request
# Max-Fowards
my $maxf = $packet->get_header( 'max-forwards' );
# we don't want to put somebody Max-Forwards: 7363535353 into the header
# and then crafting a loop, so limit it to the default value
$maxf = 70 if !$maxf || $maxf>70;
$maxf--;
if ( $maxf <= 0 ) {
# just drop
DEBUG( 10,'reached max-forwards. DROP' );
return [ undef,'max-forwards reached 0, dropping' ];
}
$packet->set_header( 'max-forwards',$maxf );
# check if last hop was strict router
# remove myself from route
my $uri = $packet->uri;
$uri = $1 if $uri =~m{^<(.*)>};
($uri) = sip_hdrval2parts( route => $uri );
my $remove_route;
if ( $uri eq $self->{contact} ) {
# last router placed myself into URI -> strict router
# get original URI back from last Route-header
my @route = $packet->get_header( 'route' );
if ( !@route ) {
# ooops, no route headers? -> DROP
return [ '','request from strict router contained no route headers' ];
}
$remove_route = $#route;
$uri = $route[-1];
$uri = $1 if $uri =~m{^<(.*)>};
$packet->set_uri($uri);
} else {
# last router was loose,remove top route if it is myself
my @route = $packet->get_header( 'route' );
if ( @route ) {
my $route = $route[0];
$route = $1 if $route =~m{^<(.*)>};
($route) = sip_hdrval2parts( route => $route );
if ( sip_uri_eq( $route,$self->{contact}) ) {
# top route was me
$remove_route = 0;
}
}
}
if ( defined $remove_route ) {
$packet->scan_header( route => [ sub {
my ($rr,$hdr) = @_;
$hdr->remove if $$rr-- == 0;
}, \$remove_route]);
}
# Add Record-Route to request, except
# to REGISTER (RFC3261, 10.2)
$packet->insert_header( 'record-route', '<'.$self->{contact}.';lr>' )
if $packet->method ne 'REGISTER';
}
return;
}
###########################################################################
# prepare packet which gets forwarded through this leg
# packet was processed before by forward_incoming on (usually) another
# leg on the same dispatcher.
# Args: ($self,$packet,$incoming_leg)
# $packet: outgoing Net::SIP::Packet, gets modified in-place
# $incoming_leg: leg where packet came in
# Returns: undef | [code,text]
# code: error code (can be empty if just drop packet on error)
# text: error description (e.g max-forwards reached..)
###########################################################################
sub forward_outgoing {
my Net::SIP::Leg $self = shift;
my ($packet,$incoming_leg) = @_;
if ( $packet->is_request ) {
# check if myself is already in Via-path
# in this case drop the packet, because a loop is detected
if ( my @via = $packet->get_header( 'via' )) {
my $branch = $self->via_branch($packet,3);
foreach my $via ( @via ) {
my (undef,$param) = sip_hdrval2parts( via => $via );
if ( substr( $param->{branch},0,length($branch) ) eq $branch ) {
DEBUG( 10,'loop detected because outgoing leg is in Via. DROP' );
return [ undef,'loop detected on outgoing leg, dropping' ];
}
}
}
# Add Record-Route to request, except
# to REGISTER (RFC3261, 10.2)
# This is necessary, because these information are used in in new requests
# from UAC to UAS, but also from UAS to UAC and UAS should talk to this leg
# and not to the leg, where the request came in.
# don't add if the upper record-route is already me, this is the case
# when incoming and outgoing leg are the same
if ( $packet->method ne 'REGISTER' ) {
my $rr;
unless ( (($rr) = $packet->get_header( 'record-route' ))
and sip_uri_eq( $rr,$self->{contact} )) {
$packet->insert_header( 'record-route', '<'.$self->{contact}.';lr>' )
}
}
# strip myself from route header, because I'm done
if ( my @route = $packet->get_header( 'route' ) ) {
my $route = $route[0];
$route = $1 if $route =~m{^<(.*)>};
($route) = sip_hdrval2parts( route => $route );
if ( sip_uri_eq( $route,$self->{contact} )) {
# top route was me, remove it
my $remove_route = 0;
$packet->scan_header( route => [ sub {
my ($rr,$hdr) = @_;
$hdr->remove if $$rr-- == 0;
}, \$remove_route]);
}
}
}
return;
}
###########################################################################
# deliver packet through this leg to specified addr
# add local Via header to requests
# Args: ($self,$packet,$addr;$callback)
# $packet: Net::SIP::Packet
# $addr: ip:port where to deliver
# $callback: optional callback, if an error occured the callback will
# be called with $! as argument. If no error occured and the
# proto is tcp the callback will be called with error=0 to show
# that the packet was definitly delivered (and need not retried)
###########################################################################
sub deliver {
my Net::SIP::Leg $self = shift;
my ($packet,$addr,$callback) = @_;
my $isrq = $packet->is_request;
if ( $isrq ) {
# add via,
# clone packet, because I don't want to change the original
# one because it might be retried later
# (could skip this for tcp?)
$packet = $packet->clone;
$self->add_via($packet);
}
# 2xx responses to INVITE requests and the request itself must have a
# Contact, Allow and Supported header, 2xx Responses to OPTIONS need
# Allow and Supported, 405 Responses should have Allow and Supported
my ($need_contact,$need_allow,$need_supported);
my $method = $packet->method;
my $code = ! $isrq && $packet->code;
if ( $method eq 'INVITE' and ( $isrq or $code =~m{^2} )) {
$need_contact = $need_allow = $need_supported =1;
} elsif ( !$isrq and (
$code == 405 or
( $method eq 'OPTIONS' and $code =~m{^2} ))) {
$need_allow = $need_supported =1;
}
if ( $need_contact && ! ( my @a = $packet->get_header( 'contact' ))) {
# needs contact header, create from this leg and user part of from/to
my ($user) = sip_hdrval2parts( $isrq
? ( from => scalar($packet->get_header('from')) )
: ( to => scalar($packet->get_header('to')) )
);
my ($proto,$addr) = $self->{contact} =~m{^(\w+):(?:.*\@)?(.*)$};
my $contact = ( $user =~m{([^<>\@\s]+)\@} ? $1 : $user ).
"\@$addr";
$contact = $proto.':'.$contact if $contact !~m{^\w+:};
$packet->insert_header( contact => $contact );
}
if ( $need_allow && ! ( my @a = $packet->get_header( 'allow' ))) {
# insert default methods
$packet->insert_header( allow => 'INVITE, ACK, OPTIONS, CANCEL, BYE' );
}
if ( $need_supported && ! ( my @a = $packet->get_header( 'supported' ))) {
# set as empty
$packet->insert_header( supported => '' );
}
my ($proto,$host,$port) =
$addr =~m{^(?:(\w+):)?([\w\-\.]+)(?::(\d+))?$};
#DEBUG( "%s -> %s %s %s",$addr,$proto||'',$host, $port||'' );
$port ||= $proto eq 'sips' ? 5061: 5060;
$self->sendto( $packet->as_string, $host,$port,$callback )
|| return;
DEBUG( 2, "delivery from $self->{addr}:$self->{port} to $addr OK:\n%s",
$packet->dump( Net::SIP::Debug->level -2 ) );
}
###########################################################################
# send data to peer
# Args: ($self,$data,$host,$port,$callback)
# $data: string representation of SIP packet
# $host: target ip
# $port: target port
# $callback: callback for error|success, see method deliver
# Returns: $success
# $success: true if no problems occured while sending (this does not
# mean that the packet was delivered reliable!)
###########################################################################
sub sendto {
my Net::SIP::Leg $self = shift;
my ($data,$host,$port,$callback) = @_;
# XXXXX for now udp only
# for tcp the delivery might be done over multiple callbacks
# (eg whenever I can write on the socket)
# for tcp I need to handle the case where I got a request on
# the leg, then the leg got closed and the I've need to deliver
# the response over a new leg, created based on the master leg
# eg I still need to know which outgoing master leg I have,
# even if my real outgoing leg is closed (responsed might be
# delivered over the same tcp connection, but no need to do so)
if ( $self->{proto} ne 'udp' ) {
use Errno 'EINVAL';
DEBUG( 1,"can only proto udp for now, but not $self->{proto}" );
invoke_callback( $callback, EINVAL );
}
my $host4 = inet_aton( $host ) or do {
# this should not happen because host should better be IP
DEBUG( 1, "lookup problems of $host?" );
invoke_callback( $callback, EINVAL );
return;
};
my $target = sockaddr_in( $port,$host4 );
unless ( $self->{sock}->send( $data,0,$target )) {
DEBUG( 1,"send failed: callback=$callback error=$!" );
invoke_callback( $callback, $! );
return;
}
# XXXX dont forget to call callback back with error=0 if
# delivery by tcp successful
return 1;
}
###########################################################################
# receive packet
# for udp socket it just makes a recv on the socket and returns the packet
# for tcp master sockets it makes accept and creates a new leg based on
# the masters leg.
# Args: ($self)
# Returns: ($packet,$from) || ()
# $packet: Net::SIP::Packet
# $from: ip:port where it got packet from
###########################################################################
sub receive {
my Net::SIP::Leg $self = shift;
if ( $self->{proto} ne 'udp' ) {
DEBUG( 1,"only udp is supported at the moment" );
return;
}
my $from = recv( $self->{sock}, my $buf, 2**16, 0 ) or do {
DEBUG( 1,"recv failed: $!" );
return;
};
# packet must be at least 13 bytes big (first line incl version
# + final crlf crlf). Ignore anything smaller, probably keep-alives
if ( length($buf)<13 ) {
DEBUG(11,"ignored packet with len ".length($buf)." because to small (keep-alive?)");
return;
}
my $packet = eval { Net::SIP::Packet->new( $buf ) } or do {
DEBUG( 3,"cannot parse buf as SIP: $@\n$buf" );
return;
};
my ($port,$host) = unpack_sockaddr_in( $from );
$host = inet_ntoa($host);
DEBUG( 2,"received on $self->{addr}:$self->{port} from $host:$port packet\n%s",
$packet->dump( Net::SIP::Debug->level -2 ));
return ($packet,"$host:$port");
}
###########################################################################
# check if the top via header matches the transport of this call through
# this leg. Used to strip Via header in response.
# Args: ($self,$packet)
# $packet: Net::SIP::Packet (usually Net::SIP::Response)
# Returns: $bool
# $bool: true if the packets via matches this leg, else false
###########################################################################
sub check_via {
my ($self,$packet) = @_;
my ($via) = $packet->get_header( 'via' );
my ($data,$param) = sip_hdrval2parts( via => $via );
my $cmp_branch = $self->via_branch($packet,2);
return substr( $param->{branch},0,length($cmp_branch)) eq $cmp_branch;
}
###########################################################################
# add myself as Via header to packet
# Args: ($self,$packet)
# $packet: Net::SIP::Packet (usually Net::SIP::Request)
# Returns: NONE
# modifies packet in-place
###########################################################################
sub add_via {
my Net::SIP::Leg $self = shift;
my $packet = shift;
$packet->insert_header( via => $self->{via}.$self->via_branch($packet,3));
}
###########################################################################
# computes branch tag for via header
# Args: ($self,$packet,$level)
# $packet: Net::SIP::Packet (usually Net::SIP::Request)
# $level: level of detail: 1:leg, 2:call, 3:path
# Returns: $value
###########################################################################
sub via_branch {
my Net::SIP::Leg $self = shift;
my ($packet,$level) = @_;
my $val = $self->{branch};
$val .= substr( md5_hex( $packet->tid ),0,15 ) if $level>1;
$val .= substr( md5_hex(
( sort $packet->get_header( 'proxy-authorization' )),
( sort $packet->get_header( 'proxy-require' )),
$packet->get_header( 'route' ),
$packet->get_header( 'to' ),
$packet->get_header( 'from' ),
($packet->get_header( 'via' ))[0] || '',
($packet->as_parts())[1],
),0,15 ) if $level>2;
return $val;
}
###########################################################################
# check if the leg could deliver to the specified addr
# Args: ($self,($addr|%spec))
# $addr: addr|proto:addr|addr:port|proto:addr:port
# %spec: hash with keys addr,proto,port
# Returns: $bool
# $bool: true if we can deliver to $ip with $proto
###########################################################################
sub can_deliver_to {
my Net::SIP::Leg $self = shift;
my %spec;
if (@_>1) {
%spec = @_
} else {
my $spec = shift;
my ($proto,$addr) = $spec =~m{^(?:(udp|tcp):)?([^:]+)}
or return; # wrong spec?
$spec{proto} = $proto if $proto;
$spec{addr} = $addr;
# ignore port
}
# check against proto of leg
return if ( $spec{proto} && $spec{proto} ne $self->{proto} );
# XXXXX dont know how to find out if I can deliver to this addr from this
# leg without lookup up route
# therefore just return true and if you have more than one leg you have
# to figure out yourself where to send it
return 1
}
###########################################################################
# returns FD on Leg
# Args: $self
# Returns: socket of leg
###########################################################################
sub fd {
my Net::SIP::Leg $self = shift;
return $self->{sock};
}
###########################################################################
# some info about the Leg for debugging
# Args: $self
# Returns: string
###########################################################################
sub dump {
my Net::SIP::Leg $self = shift;
return ref($self)." $self->{proto}:$self->{addr}:$self->{port}";
}
###########################################################################
# returns key for leg
# Args: $self
# Returns: key (string)
###########################################################################
sub key {
my Net::SIP::Leg $self = shift;
return "$self->{proto}:$self->{addr}:$self->{port}";
}
1;