Re: [sr-dev] alias_contact()/handle_alias() ready for testing

Juha Heinanen schrieb:

"final" versions of alias functions are now ready for testing in in this sr_3.0 based nathelper.c:

http://box.tutpro.com/tmp/nathelper.c

Great, thanks.

i changed the names to more descriptive ones: add_contact_alias() and handle_ruri_alias(). also helper function rr_count(pvar) is included that assigns into the pvar the number of rr headers in incoming message (request or reply).

I just wonder why "alias" is used, and not "received". Current similar features (fix_nated_register, Path) use the term "received" to refer to the socket from which the request was received, not alias. I know your mean purpose was TCP, but IMO this is proper method to handle both, NATed and TCP clients. Thus, I think by using add_contact_received and handle_uri_received it would be easier for people to understand what the function does.

But anyway, a name is just name :-)

thanks klaus

usage example is below. i believe (until otherwise shown) that it works correctly.

if you are interested, please try with different UAs and different transports with or without nat.

-- juha

add_contact_alias()/handle_ruri_alias() usage example

supports re-use of tcp sessions between proxy and UAs. supports routing of requests to UAs behind NATs so that r-uri is always what UAs expect. proxying of media is not shown, but can be easily added.

NON_REGISTER_INITIAL_REQUESTS

• call alias_contact() for all non-register initial requests, which don't come from another proxy (which takes care of its own UAs).

• if you know that non-register initial request is going to another proxy, set TO_PROXY flag before relaying the request.

• in cases, where initial request may go to another proxy, but you are not sure about it, store the number of record-route headers in incoming request in an AVP that you can then later test in onreply route and find out, if next hop was a proxy.

route [NON_REGISTER_INITIAL_REQUESTS] {

if (!is_present_hf("Record-Route")) {
    route(ADD_CONTACT_ALIAS);
};
...
if (I_KNOW_FOR_SURE_THAT_NEXT_HOP_IS_ANOTHER_PROXY) {
    setbflag("TO_PROXY");
};

if (NEXT_HOP_MAY_BE_ANOTHER_PROXY_BUT_I_DONT_KNOW_FOR_SURE) {
    if (!rr_count($avp("rr_count"))) {
        send_reply("400", "Bad request");
        exit;

}; }; t_on_reply("REPLY"); if (!t_relay()) ...

route [ADD_CONTACT_ALIAS] { if (!add_contact_alias()) { xlog("L_ERR", "Error in aliasing contact <$ct>\n"); send_reply("400", "Bad request"); exit; }; }

REGISTER_REQUESTS

• call fix_nated_register() on register requests, if registering ua is behind nat OR is using tcp.

route [REGISTER_REQUESTS] { ... if (isflagset(FROM_NATED) || (proto == TCP)) { fix_nated_register(); if (isflagset(FROM_NATED)) { setbflag("TO_NATED"); }; }; save("location"); ...

IN_DIALOG_REQUESTS

• call handle_ruri_alias() for all in-dialog requests before t_relaying them, provided that loose_route() didn't set $du, which it does if next hop is another proxy. in the latter case set TO_PROXY fag.

route [IN_DIALOG_REQUESTS] {

loose_route();
...
if ($du == "") {
    handle_ruri_alias();
    switch ($rc) {
    case -1:
        xlog("L_ERR", "Failed to handle alias of R-URI <$ru>\n");
        send_reply("400", "Bad request");
        exit;
    case 1:
        xlog("L_INFO", "Routing in-dialog $rm from <$fu> to <$du>\n");
        break;
    case 2:
        xlog("L_INFO", "Routing in-dialog $rm from <$fu> to <$ru>\n");
        break;
     };
} else {
    setbflag("TO_PROXY");
}
t_on_reply("REPLY");
if (!t_relay()) {
    ...

REPLIES

• call add_contact_alias() on all replies except the ones that come from another proxy.

onreply_route [REPLY] {

if (!isbflagset("TO_PROXY") {
    if (is_avp_set("rr_count")) {
   if (!rr_count("$(var(rr_count)"))) {
       xlog("L_NOTICE", "Bad R-R header in reply\n");
       send_reply("400", "Bad reply");
            exit;
   };
   if ($var(rr_count) == $avp(rr_count) + 1) {
       route(ADD_CONTACT_ALIAS);
        };
    } else {
   route(ADD_CONTACT_ALIAS);

} } ...

NOTE

• do NOT call fix_nated_contact() on anything, because add_contact_alias() replaces it.

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