[sr-dev] new tmx function t_reuse_branch()

[Juha Heinanen]

as per daniel's suggestion, i wrote a new tmx function t_reuse_branch(),
which can currently be called from branch-failure route:

/**
 * Creates new "main" branch by making copy of branch-failure branch.
 * Currently the following branch attributes are included:
 * request-uri, ruid, path, instance, and branch flags.
 */
static int w_t_reuse_branch(struct sip_msg* msg, char *p1, char *p2)
{
	struct cell *t;
	int branch;

	if (msg == NULL) return -1;

	/* first get the transaction */
	if (_tmx_tmb.t_check(msg, 0) == -1) return -1;
	if ((t = _tmx_tmb.t_gett()) == 0) {
	    LM_ERR("no transaction\n");
	    return -1;
	}
	switch (get_route_type()) {
	case BRANCH_FAILURE_ROUTE:
	    /* use the reason of the winning reply */
	    if ((branch = _tmx_tmb.t_get_picked_branch()) < 0) {
		LM_CRIT("no picked branch (%d) for a final response"
			" in MODE_ONFAILURE\n", branch);
		return -1;
	    }
	    rewrite_uri(msg, &(t->uac[branch].uri));
	    set_ruid(msg, &(t->uac[branch].ruid));
	    if (t->uac[branch].path.len) {
		set_path_vector(msg, &(t->uac[branch].path));
	    } else {
        		reset_path_vector(msg);
	    }
	    setbflagsval(0, t->uac[branch].flags);
	    set_instance(msg, &(t->uac[branch].instance));
	    return 1;
	default:
	    LM_ERR("unsupported route_type %d\n", get_route_type());
	    return -1;
	}
}

the new "main" branch does not include destination uri and socket,
because i didn't find them in struct ua_client.  unless someone adds
them to struct ua_clients, they thus need to be set separately from
htable after calling t_reuse_branch().

is it ok that i commit the above function to tmx module?

in addition, i would like to add $T_reply_bf (branch flags) pv, since i
need to test some of the branch flags in other parts of branch-failure
route.

-- juha