b2b_entities: proper handling of overlapping BYE

Although in normal circumstances we should reply with a 500 reply code,
in case a BYE is received, we should process it accordingly, and as soon
as the overlapping transaction completes, we should terminate the other
leg as well.

Completes c4032f9

modules/b2b_entities/dlg.c

@@ -1198,6 +1198,55 @@ int b2b_prescript_f(struct sip_msg *msg, void *uparam)
 						{
 							LM_ERR("failed to send reply with tm\n");
 						}
+						LM_DBG("Sent reply [200] and unreffed the cell %p\n",
+							tm_tran);
+
+						tmb.unref_cell(tm_tran); /* for t_newtran() */
+						b2b_cb_flags |= B2B_NOTIFY_FL_TERM_BYE;
+						goto run_cb;
+					}
+					tmb.unref_cell(tm_tran); /* for t_newtran() */
+					B2BE_LOCK_RELEASE(table, hash_index);
+					return SCB_DROP_MSG;
+				} else
+				if(dlg->uas_tran && dlg->uas_tran!=T_UNDEFINED)
+				{
+					if (method_value != METHOD_BYE) {
+						/* We have another UAS ongoing transaction on the dialog
+						 * -> reject with 500, "Overlapping Requests" */
+						#define RETRY_AFTER_HDR "Retry-After: "
+						#define RETRY_AFTER_HDR_LEN (sizeof("Retry-After: ")-1)
+						char ra_s[RETRY_AFTER_HDR_LEN + 3 + CRLF_LEN];
+						str ra = {ra_s, 0};
+						str text = str_init("Overlapping Requests");
+						LM_DBG("Received another request when the previous "
+								"one was in process\n");
+						memcpy( ra.s+ra.len, RETRY_AFTER_HDR, RETRY_AFTER_HDR_LEN);
+						ra.len += RETRY_AFTER_HDR_LEN;
+						/* the retry value is between 0 and 10 */
+						ra.len += btostr(ra.s+ra.len, (unsigned char)(rand()%10) );
+						memcpy( ra.s+ra.len, CRLF, CRLF_LEN);
+						ra.len += CRLF_LEN;
+						/* send reply */
+						if(tmb.t_reply_with_body( tm_tran, 500,
+						&text, 0, &ra, &to_tag) < 0)
+						{
+							LM_ERR("failed to send reply with tm\n");
+						}
+						LM_DBG("Sent reply [500] and unreffed the cell %p\n",
+							tm_tran);
+						tmb.unref_cell(tm_tran); /* for t_newtran() */
+						B2BE_LOCK_RELEASE(table, hash_index);
+						return SCB_DROP_MSG;
+					} else {
+						LM_DBG("Received BYE while having an ongoing "
+							"inbound/UAS transaction\n");
+						str text_ok = str_init("OK");
+						if(tmb.t_reply_with_body( tm_tran, 200,
+						&text_ok, 0, 0, &to_tag) < 0)
+						{
+							LM_ERR("failed to send reply with tm\n");
+						}
 						LM_DBG("Sent reply [200] and unreffed the cell %p\n",
 							tm_tran);
 						tmb.unref_cell(tm_tran);
@@ -1217,38 +1266,6 @@ int b2b_prescript_f(struct sip_msg *msg, void *uparam)
 						b2b_cb_flags |= B2B_NOTIFY_FL_TERM_BYE;
 						goto run_cb;
 					}
-					tmb.unref_cell(tm_tran); /* for t_newtran() */
-					B2BE_LOCK_RELEASE(table, hash_index);
-					return SCB_DROP_MSG;
-				} else
-				if(dlg->uas_tran && dlg->uas_tran!=T_UNDEFINED)
-				{
-					/* We have another UAS ongoing transaction on the dialog
-					 * -> reject with 500, "Overlapping Requests" */
-					#define RETRY_AFTER_HDR "Retry-After: "
-					#define RETRY_AFTER_HDR_LEN (sizeof("Retry-After: ")-1)
-					char ra_s[RETRY_AFTER_HDR_LEN + 3 + CRLF_LEN];
-					str ra = {ra_s, 0};
-					str text = str_init("Overlapping Requests");
-					LM_DBG("Received another request when the previous "
-							"one was in process\n");
-					memcpy( ra.s+ra.len, RETRY_AFTER_HDR, RETRY_AFTER_HDR_LEN);
-					ra.len += RETRY_AFTER_HDR_LEN;
-					/* the retry value is between 0 and 10 */
-					ra.len += btostr(ra.s+ra.len, (unsigned char)(rand()%10) );
-					memcpy( ra.s+ra.len, CRLF, CRLF_LEN);
-					ra.len += CRLF_LEN;
-					/* send reply */
-					if(tmb.t_reply_with_body( tm_tran, 500,
-					&text, 0, &ra, &to_tag) < 0)
-					{
-						LM_ERR("failed to send reply with tm\n");
-					}
-					LM_DBG("Sent reply [500] and unreffed the cell %p\n",
-						tm_tran);
-					tmb.unref_cell(tm_tran); /* for t_newtran() */
-					B2BE_LOCK_RELEASE(table, hash_index);
-					return SCB_DROP_MSG;
 				}
 
 				/* the new request is accepted for handling */