[sr-dev] git:master: modules_k/presence: Improved handling of retransmitted SUBSCRIBE requests
Peter Dunkley
peter.dunkley at crocodile-rcs.com
Mon Jan 30 18:35:35 CET 2012
Hi,
Any retransmission will cause the problem, so anyone using UDP over the
Internet to a Kamailio presence server where there is occasional
packet-loss will see it. It was just first noticed here under heavy
load.
By creating a new transaction and absorbing the retransmissions, do you
mean calling t_newtran()/t_release() when the SUBSCRIBE is received?
If so I didn't think of that. It'd make sense to do that too. I think
the presence module should cope with retransmissions (especially as we
need it to cope in a multi-server environment with
load-balancers/fail-over and a shared database). But if using
t_newtran()/t_release() will handle retransmissions in the normal case
it should help reduce the load on the database.
Thanks,
Peter
On Mon, 2012-01-30 at 18:26 +0100, Daniel-Constantin Mierla wrote:
> Hello,
>
> it can be held for next minor release to be tested more, if you feel
> it is better (we have to include something there as well :-) ). From
> commit log I understood is happening usually under RLS heavy load with
> retransmissions, does not help creating the transaction and absorbing
> the retransmissions with tm?
>
> Cheers,
> Daniel
>
> On 1/30/12 6:19 PM, Peter Dunkley wrote:
>
> > Hello,
> >
> > I believe that this bug also affects the 3.2 branch, but the change
> > is quite big and with the next release of 3.2 due tomorrow I thought
> > it best to hold off "cherry-pick"ing it until after the release.
> > That is, unless anyone else thinks it should go in there?
> >
> > Regards,
> >
> > Peter
> >
> > On Mon, 2012-01-30 at 18:16 +0100, Peter Dunkley wrote:
> >
> > > Module: sip-router
> > > Branch: master
> > > Commit: e6a50c5c0957a5ad3e08e57ede5be775a41ac24f
> > > URL: http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=e6a50c5c0957a5ad3e08e57ede5be775a41ac24f
> > >
> > > Author: pd <peter.dunkley at crocodile-rcs.com>
> > > Committer: pd <peter.dunkley at crocodile-rcs.com>
> > > Date: Mon Jan 30 17:06:42 2012 +0000
> > >
> > > modules_k/presence: Improved handling of retransmitted SUBSCRIBE requests
> > >
> > > - handle_subscribe() doesn't handle retransmitted SUBSCRIBEs properly. This was
> > > noticed with back-end SUBSCRIBEs from RLS under heavy load (also tried TCP
> > > here but under-load this caused a different set of problems with buffer
> > > sizes and buffers taking too long to process).
> > > - Although this was originally observed with RLS back-end SUBSCRIBEs it
> > > appears to be a general issue when UDP is used.
> > > - There were two main problems:
> > > 1) On an un-SUBSCRIBE the record in the hash-table or DB will be removed. If
> > > the un-SUBSCRIBE is retransmitted there is no record to be found and
> > > handle_subscribe() fails.
> > > 2) After fixing 1, and on re-SUBSCRIBE, remote CSeq's with lower than
> > > expected values cause failures. This can also happen when there are
> > > retransmissions.
> > > - The fix was to catch both these cases and treat them as a special class of
> > > error. In these two cases and when the protocol is UDP, a correct-looking
> > > 2XX response is sent, but no further processing (database updates, sending
> > > NOTIFY, and so on) is performed on the SUBSCRIBE request.
> > > - Also modified the query in get_database_info() to just use Call-ID, To-tag,
> > > and From-tag for dialog matching (so it duplicates the query from
> > > get_stored_info()) as the query that was there looked a little aggressive.
> > >
> > > ---
> > >
> > > modules_k/presence/subscribe.c | 247 +++++++++++++++++++++------------------
> > > 1 files changed, 133 insertions(+), 114 deletions(-)
> > >
> > > diff --git a/modules_k/presence/subscribe.c b/modules_k/presence/subscribe.c
> > > index d11287c..8add119 100644
> > > --- a/modules_k/presence/subscribe.c
> > > +++ b/modules_k/presence/subscribe.c
> > > @@ -762,7 +762,10 @@ int handle_subscribe(struct sip_msg* msg, char* str1, char* str2)
> > > {
> > > if(get_stored_info(msg, &subs, &reply_code, &reply_str )< 0)
> > > {
> > > - LM_ERR("getting stored info\n");
> > > + if (msg->rcv.proto == PROTO_UDP)
> > > + LM_INFO("problem getting stored info - possible retransmission\n");
> > > + else
> > > + LM_ERR("getting stored info\n");
> > > goto error;
> > > }
> > > reason= subs.reason;
> > > @@ -885,9 +888,26 @@ error:
> > >
> > > if(sent_reply== 0)
> > > {
> > > - if(send_error_reply(msg, reply_code, reply_str)< 0)
> > > + if (reply_code == 200)
> > > {
> > > - LM_ERR("failed to send reply on error case\n");
> > > + if(subs.event->type & PUBL_TYPE)
> > > + {
> > > + if(send_2XX_reply(msg, 202, subs.expires,
> > > + &subs.local_contact) <0)
> > > + LM_ERR("failed to send reply on error case\n");
> > > + }
> > > + else
> > > + {
> > > + /* For presence.winfo */
> > > + if(send_2XX_reply(msg, 200, subs.expires,
> > > + &subs.local_contact) <0)
> > > + LM_ERR("failed to send reply on error case\n");
> > > + }
> > > + }
> > > + else
> > > + {
> > > + if(send_error_reply(msg, reply_code, reply_str)< 0)
> > > + LM_ERR("failed to send reply on error case\n");
> > > }
> > > }
> > >
> > > @@ -1082,21 +1102,21 @@ int extract_sdialog_info(subs_t* subs,struct sip_msg* msg, int mexp,
> > > subs->contact.s, subs->contact.len);
> > >
> > > if (EVENT_DIALOG_SLA(subs->event->evp))
> > > - {
> > > - /* user_contact at from_domain */
> > > - if(parse_uri(subs->contact.s, subs->contact.len, &uri)< 0)
> > > - {
> > > - LM_ERR("failed to parse contact uri\n");
> > > - goto error;
> > > - }
> > > - if(uandd_to_uri(uri.user, subs->from_domain, &subs->pres_uri)< 0)
> > > - {
> > > - LM_ERR("failed to construct uri\n");
> > > - goto error;
> > > - }
> > > - LM_DBG("&&&&&&&&&&&&&&& dialog pres_uri= %.*s\n",subs->pres_uri.len, subs->pres_uri.s);
> > > - }
> > > -
> > > + {
> > > + /* user_contact at from_domain */
> > > + if(parse_uri(subs->contact.s, subs->contact.len, &uri)< 0)
> > > + {
> > > + LM_ERR("failed to parse contact uri\n");
> > > + goto error;
> > > + }
> > > + if(uandd_to_uri(uri.user, subs->from_domain, &subs->pres_uri)< 0)
> > > + {
> > > + LM_ERR("failed to construct uri\n");
> > > + goto error;
> > > + }
> > > + LM_DBG("&&&&&&&&&&&&&&& dialog pres_uri= %.*s\n",
> > > + subs->pres_uri.len, subs->pres_uri.s);
> > > + }
> > >
> > > /*process record route and add it to a string*/
> > > if(*to_tag_gen && msg->record_route!=NULL)
> > > @@ -1152,18 +1172,17 @@ int get_stored_info(struct sip_msg* msg, subs_t* subs, int* reply_code,
> > > unsigned int hash_code;
> > >
> > > /* first try to_user== pres_user and to_domain== pres_domain */
> > > -
> > > - if(subs->pres_uri.s == NULL)
> > > - {
> > > - uandd_to_uri(subs->to_user, subs->to_domain, &pres_uri);
> > > - if(pres_uri.s== NULL)
> > > - {
> > > - LM_ERR("creating uri from user and domain\n");
> > > - return -1;
> > > - }
> > > - }
> > > - else
> > > - pres_uri = subs->pres_uri;
> > > + if(subs->pres_uri.s == NULL)
> > > + {
> > > + uandd_to_uri(subs->to_user, subs->to_domain, &pres_uri);
> > > + if(pres_uri.s== NULL)
> > > + {
> > > + LM_ERR("creating uri from user and domain\n");
> > > + return -1;
> > > + }
> > > + }
> > > + else
> > > + pres_uri = subs->pres_uri;
> > >
> > > hash_code= core_hash(&pres_uri, &subs->event->name, shtable_size);
> > > lock_get(&subs_htable[hash_code].lock);
> > > @@ -1176,14 +1195,13 @@ int get_stored_info(struct sip_msg* msg, subs_t* subs, int* reply_code,
> > > }
> > > lock_release(&subs_htable[hash_code].lock);
> > >
> > > - if(subs->pres_uri.s)
> > > - goto not_found;
> > > + if(subs->pres_uri.s)
> > > + goto not_found;
> > >
> > > - pkg_free(pres_uri.s);
> > > + pkg_free(pres_uri.s);
> > > pres_uri.s= NULL;
> > > -
> > >
> > > - LM_DBG("record not found using R-URI search iteratively\n");
> > > + LM_DBG("record not found using R-URI search iteratively\n");
> > > /* take one row at a time */
> > > for(i= 0; i< shtable_size; i++)
> > > {
> > > @@ -1207,26 +1225,35 @@ int get_stored_info(struct sip_msg* msg, subs_t* subs, int* reply_code,
> > > lock_release(&subs_htable[i].lock);
> > > }
> > >
> > > +not_found:
> > > if(dbmode != DB_MEMORY_ONLY)
> > > {
> > > - return get_database_info(msg, subs, reply_code, reply_str);
> > > + return get_database_info(msg, subs, reply_code, reply_str);
> > > }
> > >
> > > -not_found:
> > > -
> > > - LM_ERR("record not found in hash_table\n");
> > > - *reply_code= 481;
> > > - *reply_str= pu_481_rpl;
> > > + if (msg->rcv.proto == PROTO_UDP && subs->expires == 0)
> > > + {
> > > + /* Assume it's a retransmission of an un-SUBSCRIBE */
> > > + LM_INFO("No matching subscription dialog found in database - possible retransmission of un-SUBSCRIBE?\n");
> > > + *reply_code= 200;
> > > + *reply_str= su_200_rpl;
> > > + }
> > > + else
> > > + {
> > > + /* It's definitely an error */
> > > + LM_ERR("record not found in hash_table\n");
> > > + *reply_code= 481;
> > > + *reply_str= pu_481_rpl;
> > > + }
> > >
> > > return -1;
> > >
> > > found_rec:
> > > -
> > > LM_DBG("Record found in hash_table\n");
> > > -
> > > +
> > > if(!EVENT_DIALOG_SLA(s->event->evp))
> > > subs->pres_uri= pres_uri;
> > > -
> > > +
> > > subs->version = s->version;
> > > subs->status= s->status;
> > > if(s->reason.s && s->reason.len)
> > > @@ -1257,14 +1284,25 @@ found_rec:
> > >
> > > if(subs->remote_cseq<= s->remote_cseq)
> > > {
> > > - LM_ERR("wrong sequence number;received: %d - stored: %d\n",
> > > - subs->remote_cseq, s->remote_cseq);
> > > -
> > > - *reply_code= 400;
> > > - *reply_str= pu_400_rpl;
> > >
> > > lock_release(&subs_htable[i].lock);
> > > - goto error;
> > > + if (msg->rcv.proto == PROTO_UDP)
> > > + {
> > > + /* Assume it's a retransmission of a SUBSCRIBE */
> > > + LM_INFO("Possible retransmission of SUBSCRIBE?\n");
> > > + *reply_code= 200;
> > > + *reply_str= su_200_rpl;
> > > + return -1;
> > > + }
> > > + else
> > > + {
> > > + /* It's definitely an error */
> > > + LM_ERR("wrong sequence number received: %d - stored: %d\n",
> > > + subs->remote_cseq, s->remote_cseq);
> > > + *reply_code= 400;
> > > + *reply_str= pu_400_rpl;
> > > + goto error;
> > > + }
> > > }
> > > lock_release(&subs_htable[i].lock);
> > >
> > > @@ -1282,64 +1320,20 @@ error:
> > >
> > > int get_database_info(struct sip_msg* msg, subs_t* subs, int* reply_code, str* reply_str)
> > > {
> > > - db_key_t query_cols[10];
> > > - db_val_t query_vals[10];
> > > - db_key_t result_cols[9];
> > > + db_key_t query_cols[3];
> > > + db_val_t query_vals[3];
> > > + db_key_t result_cols[7];
> > > db1_res_t *result= NULL;
> > > db_row_t *row ;
> > > db_val_t *row_vals ;
> > > int n_query_cols = 0;
> > > int n_result_cols = 0;
> > > int remote_cseq_col= 0, local_cseq_col= 0, status_col, reason_col;
> > > - int record_route_col, version_col;
> > > - int pres_uri_col;
> > > + int record_route_col, version_col, pres_uri_col;
> > > unsigned int remote_cseq;
> > > str pres_uri, record_route;
> > > str reason;
> > >
> > > - query_cols[n_query_cols] = &str_to_user_col;
> > > - query_vals[n_query_cols].type = DB1_STR;
> > > - query_vals[n_query_cols].nul = 0;
> > > - query_vals[n_query_cols].val.str_val = subs->to_user;
> > > - n_query_cols++;
> > > -
> > > - query_cols[n_query_cols] = &str_to_domain_col;
> > > - query_vals[n_query_cols].type = DB1_STR;
> > > - query_vals[n_query_cols].nul = 0;
> > > - query_vals[n_query_cols].val.str_val = subs->to_domain;
> > > - n_query_cols++;
> > > -
> > > - query_cols[n_query_cols] = &str_watcher_username_col;
> > > - query_vals[n_query_cols].type = DB1_STR;
> > > - query_vals[n_query_cols].nul = 0;
> > > - query_vals[n_query_cols].val.str_val = subs->from_user;
> > > - n_query_cols++;
> > > -
> > > - query_cols[n_query_cols] = &str_watcher_domain_col;
> > > - query_vals[n_query_cols].type = DB1_STR;
> > > - query_vals[n_query_cols].nul = 0;
> > > - query_vals[n_query_cols].val.str_val = subs->from_domain;
> > > - n_query_cols++;
> > > -
> > > - query_cols[n_query_cols] = &str_event_col;
> > > - query_vals[n_query_cols].type = DB1_STR;
> > > - query_vals[n_query_cols].nul = 0;
> > > - query_vals[n_query_cols].val.str_val = subs->event->name;
> > > - n_query_cols++;
> > > -
> > > - query_cols[n_query_cols] = &str_event_id_col;
> > > - query_vals[n_query_cols].type = DB1_STR;
> > > - query_vals[n_query_cols].nul = 0;
> > > - if( subs->event_id.s != NULL)
> > > - {
> > > - query_vals[n_query_cols].val.str_val.s = subs->event_id.s;
> > > - query_vals[n_query_cols].val.str_val.len = subs->event_id.len;
> > > - } else {
> > > - query_vals[n_query_cols].val.str_val.s = "";
> > > - query_vals[n_query_cols].val.str_val.len = 0;
> > > - }
> > > - n_query_cols++;
> > > -
> > > query_cols[n_query_cols] = &str_callid_col;
> > > query_vals[n_query_cols].type = DB1_STR;
> > > query_vals[n_query_cols].nul = 0;
> > > @@ -1385,29 +1379,29 @@ int get_database_info(struct sip_msg* msg, subs_t* subs, int* reply_code, str* r
> > >
> > > if(result && result->n <=0)
> > > {
> > > - LM_ERR("No matching subscription dialog found in database\n");
> > > -
> > > pa_dbf.free_result(pa_db, result);
> > > - *reply_code= 481;
> > > - *reply_str= pu_481_rpl;
> > > +
> > > + if (msg->rcv.proto == PROTO_UDP && subs->expires == 0)
> > > + {
> > > + /* Assume it's a retransmission of an un-SUBSCRIBE */
> > > + LM_INFO("No matching subscription dialog found in database - possible retransmission of un-SUBSCRIBE?\n");
> > > + *reply_code= 200;
> > > + *reply_str= su_200_rpl;
> > > + }
> > > + else
> > > + {
> > > + /* It's definitely an error */
> > > + LM_ERR("No matching subscription dialog found in database\n");
> > > + *reply_code= 481;
> > > + *reply_str= pu_481_rpl;
> > > + }
> > >
> > > return -1;
> > > }
> > >
> > > row = &result->rows[0];
> > > row_vals = ROW_VALUES(row);
> > > - remote_cseq= row_vals[remote_cseq_col].val.int_val;
> > > -
> > > - if(subs->remote_cseq<= remote_cseq)
> > > - {
> > > - LM_ERR("wrong sequence number received: %d - stored: %d\n",
> > > - subs->remote_cseq, remote_cseq);
> > > - *reply_code= 400;
> > > - *reply_str= pu_400_rpl;
> > > - pa_dbf.free_result(pa_db, result);
> > > - return -1;
> > > - }
> > > -
> > > +
> > > subs->status= row_vals[status_col].val.int_val;
> > > reason.s= (char*)row_vals[reason_col].val.string_val;
> > > if(reason.s)
> > > @@ -1453,6 +1447,31 @@ int get_database_info(struct sip_msg* msg, subs_t* subs, int* reply_code, str* r
> > > subs->record_route.len= record_route.len;
> > > }
> > >
> > > + remote_cseq= row_vals[remote_cseq_col].val.int_val;
> > > + if(subs->remote_cseq<= remote_cseq)
> > > + {
> > > + pa_dbf.free_result(pa_db, result);
> > > +
> > > + if (msg->rcv.proto == PROTO_UDP)
> > > + {
> > > + /* Assume it's a retransmission of a SUBSCRIBE */
> > > + LM_INFO("Possible retransmission of SUBSCRIBE?\n");
> > > + *reply_code= 200;
> > > + *reply_str= su_200_rpl;
> > > + }
> > > + else
> > > + {
> > > + /* It's definitely an error */
> > > + LM_ERR("wrong sequence number received: %d - stored: %d\n",
> > > + subs->remote_cseq, remote_cseq);
> > > + *reply_code= 400;
> > > + *reply_str= pu_400_rpl;
> > > + }
> > > +
> > > + return -1;
> > > + }
> > > +
> > > +
> > > pa_dbf.free_result(pa_db, result);
> > > result= NULL;
> > >
> > >
> > >
> > > _______________________________________________
> > > sr-dev mailing list
> > > sr-dev at lists.sip-router.org
> > > http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev
> >
> >
> > --
> > Peter Dunkley
> > Technical Director
> > Crocodile RCS Ltd
> >
> >
> >
> > _______________________________________________
> > sr-dev mailing list
> > sr-dev at lists.sip-router.org
> > http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev
--
Peter Dunkley
Technical Director
Crocodile RCS Ltd
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