###########################################################################
# Net::SIP::Util
# various functions for helping in SIP programs
###########################################################################

use strict;
use warnings;

package Net::SIP::Util;

use Digest::MD5 'md5_hex';
use IO::Socket;
use Net::SIP::Debug;
use Carp qw(confess croak);
use base 'Exporter';

our @EXPORT_OK = qw(
    sip_hdrval2parts
    sip_parts2hdrval
    sip_uri2parts
    create_socket_to
    create_rtp_sockets
    invoke_callback
    sip_uri_eq
);
our %EXPORT_TAGS = ( all => \@EXPORT_OK );

our $RTP_MIN_PORT = 2000;
our $RTP_MAX_PORT = 12000;

###########################################################################
# creates hash from header val, e.g.
# 'Digest method="md5",qop="auth",...','www-authenticate' will result in
# ( 'Digest', { method => md5, qop => auth,... } )
# Args: ($key,$val)
#   $key: normalized key (lowercase, long)
#   $val: value
# Returns: ( $data,\%parameter )
#   $data: initial data
#   %parameter: additional parameter
###########################################################################
sub sip_hdrval2parts {
    croak( "usage: sip_hdrval2parts( key => val )" ) if @_!=2;
    my ($key,$v) = @_;
    return if !defined($v);
    my $delim = ';';
    if ( $key eq 'www-authenticate' || $key eq 'proxy-authenticate'
	|| $key eq 'authorization' || $key eq 'proxy-authorization' ) {
	# these keys have ',' instead of ';' as delimiter
	$delim = ',';
    }

    # split on delimiter (but not if quoted)
    my @v = ('');
    my $quoted = 0;
    my $bracket = 0;
    while (1) {
	if ( $v =~m{\G(.*?)([\\"<>$delim])}gc ) {
	    if ( $2 eq "\\" ) {
		$v[-1].=$1.$2.substr( $v,pos($v),1 );
		pos($v)++;
	    } elsif ( $2 eq '"' ) {
		$v[-1].=$1.$2;
		$quoted = !$quoted if ! $bracket;
	    } elsif ( $2 eq '<' ) {
		$v[-1].=$1.$2;
		$bracket = 1 if ! $bracket && ! $quoted;
	    } elsif ( $2 eq '>' ) {
		$v[-1].=$1.$2;
		$bracket = 0 if $bracket && ! $quoted;
	    } elsif ( $2 eq $delim ) {
		# next item if not quoted
		if ( ! $quoted && ! $bracket ) {
		    ( $v[-1].=$1 ) =~s{\s+$}{}; # strip trailing space
		    push @v,'' ;
		    $v =~m{\G\s+}gc; # skip space after $delim
		} else {
		    $v[-1].=$1.$2
		}
	    }
	} else {
	    # add rest to last from @v
	    $v[-1].= substr($v,pos($v)||0 );
	    last;
	}
    }

    # with delimiter ',' it starts 'Digest realm=...' so $v[0]
    # contains method and first parameter
    my $data = shift(@v);
    if ( $delim eq ',' ) {
	$data =~s{^(\S+)\s*(.*)}{$1};
	unshift @v,$2;
    }
    # rest will be interpreted as parameters with key|key=value
    my %hash;
    foreach my $vv (@v) {
	my ($key,$value) = split( m{\s*=\s*},$vv,2 );
	if ( defined($value) ) {
	    $value =~s{^"(.*)"$}{$1};  # unquote
	    # TODO Q: what's the meaning of "\%04", e.g. is it
	    # '%04' or "\\\004" ??
	    $value =~s{\\(.)}{$1}sg;   # unescape backslashes
	    $value =~s{%([a-fA-F][a-fA-F])}{ chr(hex($1)) }esg; # resolve uri encoding
	}
	$hash{lc($key)} = $value;
    }
    return ($data,\%hash);
}


###########################################################################
# reverse to sip_hdrval2parts
# Args: ($key,$data,\%parameter)
#   $key: normalized key (lowercase, long)
#   $data: initial data
#   %parameter: additional parameter
# Returns: $val
#   $val: value
###########################################################################
sub sip_parts2hdrval {
    my ($key,$data,$param) = @_;

    my $delim = ';';
    if ( $key eq 'www-authenticate' || $key eq 'proxy-authenticate'
	|| $key eq 'authorization' || $key eq 'proxy-authorization' ) {
	# these keys have ',' instead of ';' as delimiter
	$delim = ',';
    }

    my $val = $data; # FIXME: need to escape $data?
    for my $k ( sort keys %$param ) {
	$val .= $delim.$k;
	my $v = $param->{$k};
	if ( defined $v ) {
	    # escape special chars
	    $v =~s{([%\r\n\t"[:^print:]])}{ sprintf "%%%02x",ord($1) }sg;
	    $v = '"'.$v.'"' if $v =~m{\s|$delim};
	    $val .= '='.$v
	}
    }
    return $val;
}


###########################################################################
# extract parts from SIP URI
# Args: $uri
# Returns: $domain || ($domain,$user,$proto,$data,$param)
#  $domain: SIP domain maybe with port
#  $user:   user part
#  $proto:  'sip'|'sips'
#  $data:   full part before any params
#  $param:  hashref with params, e.g { transport => 'udp',... }
###########################################################################
sub sip_uri2parts {
    my $uri = shift;
    $uri = $1 if $uri =~m{<([^>]+)>\s*$}i;
    my ($data,$param) = sip_hdrval2parts( uri => $uri );
    if ( $data =~m{^(?:(sips?):)?(?:([^\s\@]*)\@)?([\w\-\.:]+)}i ) {
	my ($proto,$user,$domain) = ($1,$2,$3);
	$proto ||= 'sip';
	return wantarray
	    ? ($domain,$user,lc($proto),$data,$param)
	    : $domain
    } else {
	return;
    }
}

###########################################################################
# returns true if two URIs are the same
# Args: $uri1,$uri2
# Returns: true if both URI point to same address
###########################################################################
sub sip_uri_eq {
    my ($uri1,$uri2) = @_;
    return 1 if $uri1 eq $uri2; # shortcut for common case
    my ($d1,$u1,$p1) = sip_uri2parts($uri1);
    my ($d2,$u2,$p2) = sip_uri2parts($uri2);
    my $port1 = $d1 =~s{:(\d+)$|\[(\d+)\]$}{} ? $1||$2
	: $p1 eq 'sips' ? 5061 : 5060;
    my $port2 = $d2 =~s{:(\d+)$|\[(\d+)\]$}{} ? $1||$2
	: $p2 eq 'sips' ? 5061 : 5060;
    return lc($d1) eq lc($d2)
	&& $port1 == $port2
	&& ( defined($u1) ? defined($u2) && $u1 eq $u2 : ! defined($u2))
	&& $p1 eq $p2;
}

###########################################################################
# create socket preferable on port 5060 from which one might reach the given IP
# Args: ($dst_addr;$proto)
#  $dst_addr: the adress which must be reachable from this socket
#  $proto: tcp|udp, default udp
# Returns: ($sock,$ip_port) || $sock || ()
#  $sock: the created socket
#  $ip_port: ip:port of socket, only given if called in array context
# Comment: the IP it needs to come from works by creating a udp socket
#  to this host and figuring out it's IP by calling getsockname. Then it
#  tries to create a socket on this IP using port 5060 and if this does
#  not work it tries the port 5062..5100 and if this does not work too
#  it let the system use a random port
#  If creating of socket fails it returns () and $! is set
###########################################################################
sub create_socket_to {
    my ($dst_addr,$proto) = @_;
    $proto ||= 'udp';

    my $laddr = do {
	$dst_addr =~s{:.*}{}; # in case ip:port was given
	my $sock = IO::Socket::INET->new(
	    PeerAddr => $dst_addr,
	    PeerPort => 5060,
	    Proto => 'udp'
	) || return; # No route?
	my $x = getsockname($sock) or return;
	my (undef,$addr) = unpack_sockaddr_in( $x );
	inet_ntoa( $addr );
    };
    DEBUG( "Local IP is $laddr" );

    # Bind to this IP
    # First try port 5060..5100, if they are all used use any port
    # I get from the system
    my ($sock,$port);
    for my $p ( 5060,5062..5100 ) {
	DEBUG( "try to listen on $laddr:$p" );
	$sock = IO::Socket::INET->new(
	    LocalAddr => $laddr,
	    LocalPort => $p,
	    Proto => $proto,
	);
	if ( $sock ) {
	    $port = $p;
	    last
	}
    }
    if ( ! $sock ) {
	$sock = IO::Socket::INET->new(
	    LocalAddr => $laddr, # use any port
	    Proto => $proto,
	) || return;
	$port = (unpack_sockaddr_in( getsockname($sock)))[0];
    }
    DEBUG( "listen on $laddr:$port" );

    return wantarray ? ($sock,"$laddr:$port" ) : $sock;
}

###########################################################################
# create RTP/RTCP sockets
# Args: ($laddr;$range,$min,$max,$tries)
#   $laddr: local addr
#   $range: how many sockets, 2 if not defined
#   $min: minimal port number, default $RTP_MIN_PORT
#   $max: maximal port number, default 10000 more than $min
#      or $RTP_MAX_PORT if $min not given
#   $tries: how many tries, default 100
# Returns: ($port,$rtp_sock,$rtcp_sock,@more_socks)
#   $port:      port of RTP socket, port for RTCP is port+1
#   $rtp_sock:  socket for RTP data
#   $rtcp_sock: socket for RTCP data
#   @more_socks: more sockets (if range >2)
###########################################################################
sub create_rtp_sockets {
    my ($laddr,$range,$min,$max,$tries) = @_;
    $range ||= 2;
    if ( ! $min ) {
	$min = $RTP_MIN_PORT;
	$max ||= $RTP_MAX_PORT;
    } else {
	$max ||= $min+10000;
    }
    $min += $min%2; # make even
    $tries ||= 1000;

    my $diff2 = int(($max-$min)/2) - $range +1;

    my (@socks,$port);
    while ( $tries-- >0 ) {

	last if @socks == $range;
	map { close($_) } @socks;
	@socks = ();

	$port = 2*int(rand($diff2)) + $min;
	for( my $i=0;$i<$range;$i++ ) {
	    push @socks, IO::Socket::INET->new(
		Proto => 'udp',
		LocalAddr => $laddr,
		LocalPort => $port + $i,
	    ) || last;
	}
    }
    return if @socks != $range; # failed
    return ($port,@socks);
}

###########################################################################
# helper to call callback, set variable..
# Args: ($cb;@args)
#  $cb:  callback
#  @args: additional args for callback
# Returns: $rv
#  $rv: return value of callback
# Comment:
# callback can be
# - code ref: will be called with $cb->(@args)
# - object with method run, will be called with $cb->run(@args)
# - array-ref with [ \&sub,@myarg ], will be called with $sub->(@myarg,@args)
# - scalar ref: the scalar will be set to $args[0] if @args, otherwise true
# - regex: returns true if anything in @args matches regex
###########################################################################
sub invoke_callback {
    my ($cb,@more_args) = @_;
    if ( UNIVERSAL::isa( $cb,'CODE' )) {
	# anon sub
	return $cb->(@more_args)
    } elsif ( my $sub = UNIVERSAL::can( $cb,'run' )) {
	# Callback object
	return $sub->($cb,@more_args );
    } elsif ( UNIVERSAL::isa( $cb,'ARRAY' )) {
	my ($sub,@args) = @$cb;
	# [ \&sub,@arg ]
	return $sub->( @args,@more_args );
    } elsif ( UNIVERSAL::isa( $cb,'Regexp' )) {
	@more_args or return;
	for(@more_args) {
	    return 1 if m{$cb}
	}
	return 0;
    } elsif ( UNIVERSAL::isa( $cb,'SCALAR' ) || UNIVERSAL::isa( $cb,'REF' )) {
	# scalar ref, set to true
	$$cb = @more_args ? shift(@more_args) : 1;
	return $$cb;
    } elsif ( $cb ) {
	confess "unknown handler $cb";
    }
}


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