/**
* Callback from the dialog module when the dialog is being updated in
* its life span. We are only interested in the INVITE or UPDATE if
* SST is supported and active for this dialog. In this case, we need
* to update the expire time for the dialog based on the
* Session-Expires: header in the reINVITE/UPDATE request.
*
* When this callback returns control to the dialog module it WILL
* reset the timeout of the dialog. We need to make sure we set the
* AVP here or the dialog timeout will be reset to the DEFAULT value
* if this is a different transaction. (so the AVP value is gone)
*
* @param did - The dialog structure. The pointer is used as an ID.
* @param type - The reason for the callback. DLGCB_REQ_WITHIN
* @param params - The sst information
*/
static void sst_dialog_request_within_CB(struct dlg_cell* did, int type,
struct dlg_cb_params * params)
{
sst_info_t *info = (sst_info_t *)*(params->param);
sst_msg_info_t minfo = {0,0,0,0};
struct sip_msg* msg = params->req;
if (msg->first_line.type == SIP_REQUEST) {
if ((msg->first_line.u.request.method_value == METHOD_INVITE ||
msg->first_line.u.request.method_value == METHOD_UPDATE)) {
LM_DBG("Update by a REQUEST. %.*s\n",
msg->first_line.u.request.method.len,
msg->first_line.u.request.method.s);
if (parse_msg_for_sst_info(msg, &minfo)) {
LM_ERR("failed to parse sst information\n");
return;
}
/* Early resetting of the value here */
set_timeout_avp(msg, minfo.se);
info->interval = minfo.se;
}
else if (msg->first_line.u.request.method_value == METHOD_PRACK) {
/* Special case here. The PRACK will cause the dialog
* module to reset the timeout value to the ldg->lifetime
* value and look for the new AVP value bound to the
* 1XX/PRACK/200OK/ACK transaction and not to the
* INVITE/200OK avp value. So we need to set the AVP
* again! I think this is a bug in the dialog module,
* either it should ignore PRACK like it ignored ACK, or
* the setting of the timeout value when returning to the
* confiremed callback code should look for the new AVP
* value, which is does not.
*/
LM_DBG("PRACK workaround applied!\n");
set_timeout_avp(msg, info->interval);
}
}
else if (msg->first_line.type == SIP_REPLY) {
if ((msg->first_line.u.reply.statuscode > 199 &&
msg->first_line.u.reply.statuscode < 300)) {
/*
* To spec (RFC) the internal time out value so not be reset
* until here.
*/
LM_DBG("Update by a REPLY %d %.*s\n",
msg->first_line.u.reply.statuscode,
msg->first_line.u.reply.reason.len,
msg->first_line.u.reply.reason.s);
if (parse_msg_for_sst_info(msg, &minfo)) {
LM_ERR("failed to parse sst information\n");
return;
}
set_timeout_avp(msg, minfo.se);
info->interval = minfo.se;
}
}
}
/**
* This callback is called on any response message in the lifespan of
* the dialog. The callback is called just before the message is
* copied to pkg memory so it is still mutable.
*
* @param did - The dialog structure. The pointer is used as an ID.
* @param type - The reason for the callback. DLGCB_CONFIRMED
* @param params - The sst information
*/
static void sst_dialog_response_fwded_CB(struct dlg_cell* did, int type,
struct dlg_cb_params * params)
{
struct sip_msg* msg = params->msg;
int *param;
/*
* This test to see if the message is a response sould ALWAYS be
* true. This callback should not get called for requests. But
* lets be safe.
*/
if (msg->first_line.type == SIP_REPLY) {
sst_msg_info_t minfo = {0,0,0,0};
sst_info_t *info = (sst_info_t *)*(params->param);
LM_DBG("Dialog seen REPLY %d %.*s\n",
msg->first_line.u.reply.statuscode,
msg->first_line.u.reply.reason.len,
msg->first_line.u.reply.reason.s);
/*
* Need to check to see if it is a 422 response. If it is,
* make sure our Min-SE: for this dialog is set at least as
* large as in the Min-SE: in the reply 422 message. If not,
* we will create an INVITE, 422 loop.
*/
if (msg->first_line.u.reply.statuscode == 422) {
if (parse_msg_for_sst_info(msg, &minfo)) {
LM_ERR("failed to prase sst information for thr 422 reply\n");
return;
}
/* Make sure we do not try to use anything smaller */
info->interval = MAX(info->interval, minfo.min_se);
return; /* There is nothing else to do with this */
}
/*
* We need to get the method this reply is for from the CSEQ
* body. The RFC states we can only play with 2XX from the
* INVITE or reINVTE/UPDATE.
*/
if (!msg->cseq && ((parse_headers(msg, HDR_CSEQ_F, 0) == -1) || !msg->cseq)) {
LM_ERR("failed to parse CSeq\n");
return;
}
/* 2XX replies to INVITES only !*/
if (msg->first_line.u.reply.statuscode > 199 &&
msg->first_line.u.reply.statuscode < 300 &&
(get_cseq(msg)->method_id == METHOD_INVITE ||
get_cseq(msg)->method_id == METHOD_UPDATE)) {
if (parse_msg_for_sst_info(msg, &minfo)) {
LM_ERR("failed to parse sst information for the 2XX reply\n");
return;
}
LM_DBG("parsing 200 OK response %d / %d\n", minfo.supported, minfo.se);
if (info->supported != SST_UAC) {
info->supported = (minfo.supported?SST_UAS:SST_UNDF);
}
if (minfo.se != 0) {
if (sst_interval > minfo.min_se)
info->interval = sst_interval;
else
info->interval = MAX(minfo.se, sst_min_se);
LM_DBG("UAS supports timer\n");
if (set_timeout_avp(msg, info->interval)) {
// FIXME: need an error message here
return;
}
}
else {
/* no se header found, we want to resquest it. */
if (info->supported == SST_UAC) {
char se_buf[80];
LM_DBG("UAC supports timer\n");
LM_DBG("appending the Session-Expires: header to the 2XX reply."
" UAC will deal with it.\n");
/*
* GOOD! we can just insert the Session-Expires:
* header and forward back to the UAC and it will
* deal with refreshing the session.
*/
if (sst_interval > minfo.min_se)
info->interval = sst_interval;
else
info->interval = MAX(minfo.se, sst_min_se);
snprintf(se_buf, 80, "Session-Expires: %d;refresher=uac\r\n",
info->interval);
if (append_header(msg, se_buf)) {
LM_ERR("failed to append Session-Expires header\n");
return;
}
/* Set the dialog timeout HERE */
if (set_timeout_avp(msg, info->interval)) {
return;
}
}
else {
/* We are sunk, uac did not request it, and it
* does not support it */
LM_DBG("UAC and UAS do not support timers!"
" No session timers for this session.\n");
param = find_param_export("dialog", "default_timeout", INT_PARAM);
info->interval = param?*param:12*3600;
if (set_timeout_avp(msg, info->interval)) {
return;
}
}
}
} /* End of 2XX for an INVITE */
} /* If the msg is a repsonse and not a request */
}
/**
* Callback from the dialog module when the dialog is being updated in
* its life span. We are only interested in the INVITE or UPDATE if
* SST is supported and active for this dialog. In this case, we need
* to update the expire time for the dialog based on the
* Session-Expires: header in the reINVITE/UPDATE request.
*
* When this callback returns control to the dialog module it WILL
* reset the timeout of the dialog. We need to make sure we set the
* AVP here or the dialog timeout will be reset to the DEFAULT value
* if this is a different transaction. (so the AVP value is gone)
*
* @param did - The dialog structure. The pointer is used as an ID.
* @param type - The reason for the callback. DLGCB_REQ_WITHIN
* @param params - The sst information
*/
static void sst_dialog_request_within_CB(struct dlg_cell* did, int type,
struct dlg_cb_params * params)
{
sst_info_t *info = (sst_info_t *)*(params->param);
sst_msg_info_t minfo = {0,0,0,0};
struct sip_msg* msg = params->msg;
if (msg->first_line.type == SIP_REQUEST) {
if ((msg->first_line.u.request.method_value == METHOD_INVITE ||
msg->first_line.u.request.method_value == METHOD_UPDATE)) {
LM_DBG("Update by a REQUEST. %.*s\n",
msg->first_line.u.request.method.len,
msg->first_line.u.request.method.s);
if (parse_msg_for_sst_info(msg, &minfo)) {
// FIXME: need an error message here
return;
}
/* Early resetting of the value here */
if (minfo.se > 0) {
if (sst_interval > minfo.min_se)
info->interval = sst_interval;
else
info->interval = MAX(minfo.se, sst_min_se);
}
info->supported = (minfo.supported?SST_UAC:SST_UNDF);
set_timeout_avp(msg, info->interval);
}
else if (msg->first_line.u.request.method_value == METHOD_PRACK
|| msg->first_line.u.request.method_value == METHOD_ACK) {
/* Special case here. The PRACK will cause the dialog
* module to reset the timeout value to the ldg->lifetime
* value and look for the new AVP value bound to the
* 1XX/PRACK/200OK/ACK transaction and not to the
* INVITE/200OK avp value. So we need to set the AVP
* again!
*/
LM_DBG("ACK/PRACK workaround applied!%d\n", info->interval);
set_timeout_avp(msg, info->interval);
}
}
else if (msg->first_line.type == SIP_REPLY) {
if ((msg->first_line.u.reply.statuscode > 199 &&
msg->first_line.u.reply.statuscode < 300)) {
/*
* To spec (RFC) the internal time out value so not be reset
* until here.
*/
LM_DBG("Update by a REPLY %d %.*s\n",
msg->first_line.u.reply.statuscode,
msg->first_line.u.reply.reason.len,
msg->first_line.u.reply.reason.s);
if (parse_msg_for_sst_info(msg, &minfo)) {
// FIXME: need an error message here
return;
}
set_timeout_avp(msg, minfo.se);
info->supported = (minfo.supported?SST_UAC:SST_UNDF);
info->interval = minfo.se;
}
}
}
/**
* Every time a new dialog is created (from a new INVITE) the dialog
* module will call this callback function. We need to track the
* dialogs lifespan from this point forward until it is terminated
* with a BYE, CANCEL, etc. In the process, we will see if either or
* both ends of the conversation supports SIP Session Timers and setup
* the dialog timeout to expire at the session timer expire time. Each
* time the new re-INVITE is seen to update the SST, we will reset the
* life span of the dialog to match it.
*
* This function will setup the other types of dialog callbacks
* required to track the lifespan of the dialog. It will also start
* the state tracking to figure out if and who supports SST.
*
* As per RFC4028: Request handling:
*
* - The proxy may insert a SE header if none found.
* - The SE value can be anything >= Min-SE (if found)
* - The proxy MUST NOT add a refresher parameter to the SE.
*
* - If SE is already there, the Proxy can reduce its value but no
* lower then the Min-SE value if present.
* - If the SE value is >= Min-SE the proxy MUST NOT increase it!
* - If the SE value is < Min-SE (settable by the proxy) the proxy
* MUST increase the SE value to >= the new Min-SE.
* - The proxy MUST NOT insert or change the refresher parameter.
*
* - If the supported=timer is found, the proxy may reject the request
* with a 422 if the SE value is smaller then the local policy. The
* 422 MUST hold the proxies Min-SE value >= 90.
* - If support=timer is NOT indecated, the proxy can't reject with a
* 422 but can include/increase the MIN-SE: to be = to local policy.
* and increase the SE to match the new Min-SE value.
* - the proxy MUST NOT insert/change the Min-SE header if
* supported=timer is present. (DoS attacks)
*
* @param did - The dialog ID
* @param type - The trigger event type (CREATED)
* @param params - The pointer to nothing. As we did not attach
* anything to this callback in the dialog module.
*/
void sst_dialog_created_CB(struct dlg_cell *did, int type,
struct dlg_cb_params * params)
{
sst_info_t *info = NULL;
sst_msg_info_t minfo;
struct sip_msg* msg = params->msg;
memset(&minfo, 0, sizeof(sst_msg_info_t));
/*
* Only deal with messages flaged as SST interested.
*/
if ((msg->flags & sst_flag) != sst_flag) {
LM_DBG("SST flag was not set for this request\n");
return;
}
/*
* look only at INVITE
*/
if (msg->first_line.type != SIP_REQUEST ||
msg->first_line.u.request.method_value != METHOD_INVITE) {
LM_WARN("dialog create callback called with a non-INVITE request.\n");
return;
}
/*
* Gather all he information about SST for this message
*/
if (parse_msg_for_sst_info(msg, &minfo)) {
LM_ERR("failed to parse sst information\n");
return;
}
info = (sst_info_t *)shm_malloc(sizeof(sst_info_t));
memset(info, 0, sizeof(sst_info_t));
info->requester = (minfo.se?SST_UAC:SST_UNDF);
info->supported = (minfo.supported?SST_UAC:SST_UNDF);
info->interval = MAX(sst_interval, 90); /* For now, will set for real
* later */
if (minfo.se != 0) {
/*
* There is a SE already there, this is good, we just need to
* check the values out a little before passing it along.
*/
if (minfo.se < sst_min_se) {
/*
* Problem, the requested Session-Expires is too small for
* our local policy. We need to fix it, or reject it or
* ignore it.
*/
if (!minfo.supported) {
/*
* Increase the Min-SE: value in the request and
* forward it.
*/
char buf[80];
if (minfo.min_se) {
/* We need to update, which means, remove +
* insert */
remove_minse_header(msg);
}
info->interval = MAX(sst_min_se, minfo.min_se);
snprintf(buf, 80, "Min-SE: %d\r\n", info->interval);
if (append_header(msg, buf)) {
LM_ERR("Could not append modified Min-SE: header\n");
}
}
else if (sst_reject) {
/* Make sure that that all are at least 90 */
send_reject(msg, MAX(MAX(sst_min_se, minfo.min_se), 90));
shm_free(info);
return;
}
} /* end of se < sst_min_se */
else {
/* Use the INVITE SE: value */
info->interval = minfo.se;
}
}
else {
/*
* No Session-Expire: stated in request.
*/
char buf[80];
info->interval = MAX(minfo.min_se, sst_min_se);
if (minfo.min_se && minfo.min_se < sst_min_se) {
remove_minse_header(msg);
snprintf(buf, 80, "Min-SE: %d\r\n", info->interval);
if (append_header(msg, buf)) {
LM_ERR("failed to append modified Min-SE: header\n");
/* What to do? Let is slide, we can still work */
}
}
info->interval = MAX(info->interval, sst_interval);
info->requester = SST_PXY;
snprintf(buf, 80, "Session-Expires: %d\r\n", info->interval);
if (append_header(msg, buf)) {
LM_ERR("failed to append Session-Expires header to proxy "
"requested SST.\n");
shm_free(info);
return; /* Nothing we can do! */
}
}
setup_dialog_callbacks(did, info);
/* Early setup of default timeout */
set_timeout_avp(msg, info->interval);
return;
}
