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#The following is the complete route script. The general and module sections were comitted. The sections highlighted are the ones required for NAT traversal.
route{
if (!mf_process_maxfwd_header("10")) {
sl_send_reply("483","Too Many Hops");
exit;
}
#---- NAT Detection ----#
force_rport();
if (nat_uac_test("18")) {
if (method=="REGISTER")is_() {
fix_nated_register();
}
else {
fix_nated_contact();
}
setflag(5);
}
#---- Sequential requests section ----#
if (has_totag()) {
# sequential request withing a dialog should
# take the path determined by record-routing
if (loose_route()) {
if (is_method("BYE")) {
setflag(1); # do accounting
setflag(3); # even if the transaction fails
}
else if (is_method("INVITE")) {
record_route();
}
route(1);
}
else {
if ( is_method("ACK") ) {
if ( t_check_trans() ) {
t_relay();
exit;
}
else {
exit;
}
}
sl_send_reply("404","Not here");
}
exit;
}
#---- initial requests section ----#
if (is_method("CANCEL")) {
if (t_check_trans()) {
t_relay();
exit;
}
t_check_trans();
if (!(method=="REGISTER")is_() && is_from_local()) {
if(!allow_trusted()){
if (!proxy_authorize("", "subscriber")) {
proxy_challenge("", "0");
exit;
}
if (!db_check_from()) {
sl_send_reply("403","Forbidden auth ID");
exit;
}
consume_credentials();
# caller authenticated
}
}
#---- preloaded route checking ----#
if (loose_route()) {
xlog("L_ERR","Attempt to route with preloaded Route's
[$fu/$tu/$ru/$ci]");
if (!is_method("ACK")) {
sl_send_reply("403","Preload Route denied");
exit;
}
}
#---- record routing ----#
if (!is_method("REGISTER|MESSAGE"))
record_route();
# account only INVITEs
if (is_method("INVITE")) {
setflag(1); # do accounting
}
#---- Routing to external domains ----#
if (!is_uri_host_local())
{
append_hf("P-hint: outbound\r\n");
if(is_uri_host_local()) {
route(1);
}
else {
sl_send_reply("403","Not here");
}
}
if (is_method("PUBLISH"))
{
sl_send_reply("503", "Service Unavailable");
exit;
}
if (is_method("REGISTER"))
{
# authenticate the REGISTER requests (uncomment to enable auth)
if (!www_authorize("", "subscriber"))
{
www_challenge("", "0");
exit;
}
if (!db_check_to())
{
sl_send_reply("403","Forbidden auth ID");
exit;
}
#-- Request is behind NAT(flag5) save with bflag 6 -#
#---- Use bflag 7 to start SIP pinging (Options) ---#
if (isflagset(5)) {
setbflag(6);
setbflag(7);
};
if (!save("location")) {
sl_reply_error();
exit;
}
if ($rU==NULL) {
# request with no Username in RURI
sl_send_reply("484","Address Incomplete");
exit;
}
# apply DB based aliases (uncomment to enable)
alias_db_lookup("dbaliases");
# Blind call forward
if(avp_db_load("$ru","$avp(s:callfwd)")) {
$ru = $avp(s:callfwd);
#xlog("$avp(s:callfwd)");
route(1);
exit;
}
if($rU=~"^\*") {
# Route to media servers
route(5);
route(1);
}
#Dial plan processing
#xlog("$avp(s:country)");
$var(sdpid)=$avp(s:country);
$var(dpid)=$(var(sdpid){s.int});
xlog("$var(dpid)");
if(!dp_translate("$var(dpid)","$ruri.user/$ruri.user")){
send_reply("420", "Invalid Destination");
exit;
}
xlog("$avp(s:dest)");
if ($avp(s:dest)=="usrloc") {
#Route to usrloc
route(3);
}
if ($avp(s:dest)=="local") {
#route to pstn
$var(v_pr)=$avp(s:country)+$avp(s:area);
$ru="sip:"+$var(v_pr)+$rU+"@"+$rd;
xlog("$ru");
route(4);
}
if ($avp(s:dest)=="ld" || $avp(s:dest)=="int") {
#route to pstn
route(4);
}
if ($avp(s:dest)=="media") {
#route to media server
route(5);
}
send_reply("420", "Invalid Extension");
exit;
}
route[1] {
# for INVITEs enable some additional helper routes
#---- Helper route, if nat=yes in the R-URI set flag 6 ----#
#---- This is used to Process REINVITES ----#
if (subst_uri('/(sip:.*);nat=yes/\1/')){
setbflag(6);
};
#-- If caller(flag 5) or callee(flag 6) are behind NAT --#
#-- Call the route(6) to force the use of the RTP Proxy --#
if (isflagset(5)||isbflagset(6)) {
route(6);
};
if (isflagset(5)){
search_append('Contact:.*sip:[^>[:cntrl:]]*', ';nat=yes');
}
if (is_method("INVITE")) {
t_on_branch("2");
t_on_reply("2");
t_on_failure("1");
}
if (!t_relay()) {
sl_reply_error();
};
exit;
}
#Route for user lookups
route[3]{
if (!lookup("location", "m")) {
switch ($retcode) {
case -1:
case -3:
t_newtran();
t_reply("404", "Not Found");
exit;
case -2:
sl_send_reply("405", "Method Not Allowed");
exit;
}
}
# when routing via usrloc, log the missed calls also
setflag(2);
route(1);
}
route[4] {
#---- PSTN route ----#
if(!do_routing()){
send_reply("503", "No rules found matching the URI prefix");
exit;
}
#--- mark the transaction with flag 10 - route to pstn
setflag(10);
route(1);
}
route[5] {
#---- Route to media servers ----#
#xlog("route to media servers");
rewritehostport("192.168.1.202:5062");
route(1);
}
route[6] {
#---- RTP Proxy handling ---#
if (is_method("BYE|CANCEL")) {
unforce_rtp_proxy();
}
else if (is_method("INVITE")){
#---- Activates the RTP Proxy for the CALLEE ---#
force_rtp_proxy();
t_on_failure("1");
};
}
branch_route[2] {
xlog("new branch at $ru\n");
}
onreply_route[2] {
#xlog("incoming reply\n");
#---- Handling of the SDP for the 200 or 183 reply ----#
#---- If behind nat (flags 5 or 6) start RTP Proxy ----#
#---- Activates the RTP Proxy for the CALLER ----#
if ((isflagset(5) || isbflagset(6)) && status=~"(183)|(2[0-9][0-
9])"){
force_rtp_proxy();
append_hf("P-hint: onreply_route|force_rtp_proxy \r\n");
}
#---- If the CALLEE is behind NAT, fix the CONTACT HF ----#
if (isbflagset(6)) {
#-- Insert nat=yes at the end of the Contact header --#
#-- This helps with REINVITEs, --#
#- nat=yes will be included in the R-URI for seq.requests-#
search_append('Contact:.*sip:[^>[:cntrl:]]*', ';nat=yes');
append_hf("P-hint: Onreply-route - fixcontact \r\n");
fix_nated_contact();
}
exit;
}
failure_route[1] {
#---- If a failure has ocurred, deactivate the RTP Proxy ----#
if (isflagset(5) || isbflagset(6)){
unforce_rtp_proxy();
}
if (t_was_cancelled()) {
exit;
}
#- if the failure comes from a PSTN route, handle properly -#
if(isflagset(10)){
if (use_next_gw()) {
xlog ("next gateway $ru \n");
route(1);
exit;
}
else {
t_reply("503", "Service not available, no more gws");
exit;
}
}
# Redirect busy calls to a media server
if (t_check_status("486")) {
revert_uri();
sethostport("192.168.1.202:5062");
prefix("b");
t_relay();
}
# Redirect unanswered calls to the media server
if (t_check_status("480|408")) {
revert_uri;
sethostport("192.168.1.202:5062");
prefix("u");
t_relay();
}
}