chan_iax2: Block unnecessary control frames to/from the wire.

Establishing an IAX2 call between Asterisk v1.4 and v1.8 (or later)
results in an unexpected call disconnect.  The problem happens because
newer values in the enum ast_control_frame_type are not consistent between
the branch versions of Asterisk.

For example:
1) v1.4 calls v1.8 (or later) using IAX2

2) v1.8 answers and sends a connected line update control frame.  (on v1.8
AST_CONTROL_CONNECTED_LINE = 22)

3) v1.4 receives the control frame as an end-of-q (on v1.4
AST_CONTROL_END_OF_Q = 22)

4) v1.4 disconnects the call once the receive queue becomes empty.

Several things are done by this patch to fix the problem and attempt to
prevent it from happening again in the future:

* Added a warning at the definition of enum ast_control_frame_type about
how to add new control frame values.

* Made block sending and receiving control frames that have no reason to
go over the wire.

* Extended the connectedline iax.conf parameter to also include the
redirecting information updates.

* Updated the connectedline iax.conf parameter documentation to include a
notice that the parameter must be "no" when the peer is an Asterisk v1.4
instance.

(closes issue AST-1302)

Review: https://reviewboard.asterisk.org/r/3174/
........

Merged revisions 407678 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 407727 from http://svn.asterisk.org/svn/asterisk/branches/11

git-svn-id: https://origsvn.digium.com/svn/asterisk/certified/branches/11.6@407746 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/channels/chan_iax2.c b/channels/chan_iax2.c
index d185f1ad5f530ed6b222caad612723ae6254c028..df945fec1ac73d8c77abf3d3049b76c7c3b6f546 100644 (file)
--- a/channels/chan_iax2.c
+++ b/channels/chan_iax2.c
@@ -1303,6 +1303,92 @@ static void iax2_lock_owner(int callno)
        }
 }
 
+/*!
+ * \internal
+ * \brief Check if a control subtype is allowed on the wire.
+ *
+ * \param subtype Control frame subtype to check if allowed to/from the wire.
+ *
+ * \retval non-zero if allowed.
+ */
+static int iax2_is_control_frame_allowed(int subtype)
+{
+       enum ast_control_frame_type control = subtype;
+       int is_allowed;
+
+       /*
+        * Note: If we compare the enumeration type, which does not have any
+        * negative constants, the compiler may optimize this code away.
+        * Therefore, we must perform an integer comparison here.
+        */
+       if (subtype == -1) {
+               return -1;
+       }
+
+       /* Default to not allowing control frames to pass. */
+       is_allowed = 0;
+
+       /*
+        * The switch default is not present in order to take advantage
+        * of the compiler complaining of a missing enum case.
+        */
+       switch (control) {
+       /*
+        * These control frames make sense to send/receive across the link.
+        */
+       case AST_CONTROL_HANGUP:
+       case AST_CONTROL_RING:
+       case AST_CONTROL_RINGING:
+       case AST_CONTROL_ANSWER:
+       case AST_CONTROL_BUSY:
+       case AST_CONTROL_TAKEOFFHOOK:
+       case AST_CONTROL_OFFHOOK:
+       case AST_CONTROL_CONGESTION:
+       case AST_CONTROL_FLASH:
+       case AST_CONTROL_WINK:
+       case AST_CONTROL_OPTION:
+       case AST_CONTROL_RADIO_KEY:
+       case AST_CONTROL_RADIO_UNKEY:
+       case AST_CONTROL_PROGRESS:
+       case AST_CONTROL_PROCEEDING:
+       case AST_CONTROL_HOLD:
+       case AST_CONTROL_UNHOLD:
+       case AST_CONTROL_VIDUPDATE:
+       case AST_CONTROL_CONNECTED_LINE:
+       case AST_CONTROL_REDIRECTING:
+       case AST_CONTROL_T38_PARAMETERS:
+       case AST_CONTROL_AOC:
+       case AST_CONTROL_INCOMPLETE:
+       case AST_CONTROL_MCID:
+               is_allowed = -1;
+               break;
+
+       /*
+        * These control frames do not make sense to send/receive across the link.
+        */
+       case _XXX_AST_CONTROL_T38:
+               /* The control value is deprecated in favor of AST_CONTROL_T38_PARAMETERS. */
+       case AST_CONTROL_SRCUPDATE:
+               /* Across an IAX link the source is still the same. */
+       case AST_CONTROL_TRANSFER:
+               /* A success/fail status report from calling ast_transfer() on this machine. */
+       case AST_CONTROL_CC:
+               /* The payload contains pointers that are valid for the sending machine only. */
+       case AST_CONTROL_SRCCHANGE:
+               /* Across an IAX link the source is still the same. */
+       case AST_CONTROL_READ_ACTION:
+               /* The action can only be done by the sending machine. */
+       case AST_CONTROL_END_OF_Q:
+               /* This frame would cause the call to unexpectedly hangup. */
+       case AST_CONTROL_UPDATE_RTP_PEER:
+               /* Only meaningful across a bridge on this machine for direct-media exchange. */
+       case AST_CONTROL_PVT_CAUSE_CODE:
+               /* Intended only for the sending machine's local channel structure. */
+               break;
+       }
+       return is_allowed;
+}
+
 static void mwi_event_cb(const struct ast_event *event, void *userdata)
 {
        /* The MWI subscriptions exist just so the core knows we care about those
@@ -5743,8 +5829,13 @@ static int iax2_indicate(struct ast_channel *c, int condition, const void *data,
                }
                break;
        case AST_CONTROL_CONNECTED_LINE:
-               if (!ast_test_flag64(pvt, IAX_SENDCONNECTEDLINE))
+       case AST_CONTROL_REDIRECTING:
+               if (!ast_test_flag64(pvt, IAX_SENDCONNECTEDLINE)) {
+                       /* We are not configured to allow sending these updates. */
+                       ast_debug(2, "Callno %u: Config blocked sending control frame %d.\n",
+                               callno, condition);
                        goto done;
+               }
                break;
        case AST_CONTROL_PVT_CAUSE_CODE:
                res = -1;
@@ -7590,6 +7681,12 @@ static int __send_command(struct chan_iax2_pvt *i, char type, int command, unsig
 
 static int send_command(struct chan_iax2_pvt *i, char type, int command, unsigned int ts, const unsigned char *data, int datalen, int seqno)
 {
+       if (type == AST_FRAME_CONTROL && !iax2_is_control_frame_allowed(command)) {
+               /* Control frame should not go out on the wire. */
+               ast_debug(2, "Callno %u: Blocked sending control frame %d.\n",
+                       i->callno, command);
+               return 0;
+       }
        return __send_command(i, type, command, ts, data, datalen, seqno, 0, 0, 0);
 }
 
@@ -10557,13 +10654,6 @@ static int socket_process_helper(struct iax2_thread *thread)
                                iaxs[fr->callno]->videoformat = ast_format_to_old_bitfield(&f.subclass.format);
                        }
                }
-               if (f.frametype == AST_FRAME_CONTROL && iaxs[fr->callno]->owner) {
-                       if (f.subclass.integer == AST_CONTROL_BUSY) {
-                               ast_channel_hangupcause_set(iaxs[fr->callno]->owner, AST_CAUSE_BUSY);
-                       } else if (f.subclass.integer == AST_CONTROL_CONGESTION) {
-                               ast_channel_hangupcause_set(iaxs[fr->callno]->owner, AST_CAUSE_CONGESTION);
-                       }
-               }
                if (f.frametype == AST_FRAME_IAX) {
                        AST_SCHED_DEL(sched, iaxs[fr->callno]->initid);
                        /* Handle the IAX pseudo frame itself */
@@ -11774,17 +11864,48 @@ immediatedial:
                ast_mutex_unlock(&iaxsl[fr->callno]);
                return 1;
        }
-       /* Don't allow connected line updates unless we are configured to */
-       if (f.frametype == AST_FRAME_CONTROL && f.subclass.integer == AST_CONTROL_CONNECTED_LINE) {
-               struct ast_party_connected_line connected;
 
-               if (!ast_test_flag64(iaxs[fr->callno], IAX_RECVCONNECTEDLINE)) {
+       if (f.frametype == AST_FRAME_CONTROL) {
+               if (!iax2_is_control_frame_allowed(f.subclass.integer)) {
+                       /* Control frame not allowed to come from the wire. */
+                       ast_debug(2, "Callno %u: Blocked receiving control frame %d.\n",
+                               fr->callno, f.subclass.integer);
                        ast_variables_destroy(ies.vars);
                        ast_mutex_unlock(&iaxsl[fr->callno]);
                        return 1;
                }
+               if (f.subclass.integer == AST_CONTROL_CONNECTED_LINE
+                       || f.subclass.integer == AST_CONTROL_REDIRECTING) {
+                       if (!ast_test_flag64(iaxs[fr->callno], IAX_RECVCONNECTEDLINE)) {
+                               /* We are not configured to allow receiving these updates. */
+                               ast_debug(2, "Callno %u: Config blocked receiving control frame %d.\n",
+                                       fr->callno, f.subclass.integer);
+                               ast_variables_destroy(ies.vars);
+                               ast_mutex_unlock(&iaxsl[fr->callno]);
+                               return 1;
+                       }
+               }
+
+               iax2_lock_owner(fr->callno);
+               if (iaxs[fr->callno] && iaxs[fr->callno]->owner) {
+                       if (f.subclass.integer == AST_CONTROL_BUSY) {
+                               ast_channel_hangupcause_set(iaxs[fr->callno]->owner, AST_CAUSE_BUSY);
+                       } else if (f.subclass.integer == AST_CONTROL_CONGESTION) {
+                               ast_channel_hangupcause_set(iaxs[fr->callno]->owner, AST_CAUSE_CONGESTION);
+                       }
+                       ast_channel_unlock(iaxs[fr->callno]->owner);
+               }
+       }
+
+       if (f.frametype == AST_FRAME_CONTROL
+               && f.subclass.integer == AST_CONTROL_CONNECTED_LINE) {
+               struct ast_party_connected_line connected;
 
-               /* Initialize defaults */
+               /*
+                * Process a received connected line update.
+                *
+                * Initialize defaults.
+                */
                ast_party_connected_line_init(&connected);
                connected.id.number.presentation = iaxs[fr->callno]->calling_pres;
                connected.id.name.presentation = iaxs[fr->callno]->calling_pres;
@@ -11807,6 +11928,7 @@ immediatedial:
                }
                ast_party_connected_line_free(&connected);
        }
+
        /* Common things */
        f.src = "IAX2";
        f.mallocd = 0;

diff --git a/configs/iax.conf.sample b/configs/iax.conf.sample
index 0de3d3573ba49bcbb3311a0b80f2cf9b0e198899..eb82ad8cd8afc292abbd85dc46d1fe9a12bdb410 100644 (file)
--- a/configs/iax.conf.sample
+++ b/configs/iax.conf.sample
@@ -607,14 +607,18 @@ description=Demo System At Digium    ; Description of this peer, as listed by
 ; IPs can also optionally be given but are not required.  Caller*ID can be
 ; suggested to the other side as well if it is for example a phone instead of
 ; another PBX.
-;connectedline=yes ; Set how connected line information is handled for this
-;                  ; peer. If set to "yes", both sending and receiving
-;                  ; connected line information will be enabled. If set to
-;                  ; "send", this peer will send connected line information
-;                  ; but will not process connected line updates. If set to
-;                  ; "receive", connected line updates will be processed
-;                  ; but not sent. If set to "no", connected line updates
-;                  ; will be disabled. Default is "no".
+;connectedline=yes ; Set if connected line and redirecting information updates
+;                  ; are passed between Asterisk servers for this peer.
+;                  ; yes - Sending and receiving updates are enabled.
+;                  ; send - Only send updates.
+;                  ; receive - Only process received updates.
+;                  ; no - Sending and receiving updates are disabled.
+;                  ; Default is "no".
+;                  ;
+;                  ; Note: Because of an incompatibility between Asterisk v1.4
+;                  ; and Asterisk v1.8 or later, this option must be set
+;                  ; to "no" toward the Asterisk v1.4 peer.  A symptom of the
+;                  ; incompatibility is the call gets disconnected unexpectedly.
 
 
 ;[dynamichost]

diff --git a/include/asterisk/frame.h b/include/asterisk/frame.h
index 77c766711ae6311b639d9902fd4f724c67b00675..0ac0d5fd9747fd6b0d647e789b875b0af622888f 100644 (file)
--- a/include/asterisk/frame.h
+++ b/include/asterisk/frame.h
@@ -233,6 +233,18 @@ extern struct ast_frame ast_null_frame;
 /*! Reject link request */
 #define AST_HTML_LINKREJECT    20
 
+/*!
+ * \brief Internal control frame subtype field values.
+ *
+ * \warning
+ * IAX2 sends these values out over the wire.  To prevent future
+ * incompatibilities, pick the next value in the enum from whatever
+ * is on the current trunk.  If you lose the merge race you need to
+ * fix the previous branches to match what is on trunk.  In addition
+ * you need to change chan_iax2 to explicitly allow the control
+ * frame over the wire if it makes sense for the frame to be passed
+ * to another Asterisk instance.
+ */
 enum ast_control_frame_type {
        AST_CONTROL_HANGUP = 1,                 /*!< Other end has hungup */
        AST_CONTROL_RING = 2,                   /*!< Local ring */
@@ -267,6 +279,20 @@ enum ast_control_frame_type {
        AST_CONTROL_MCID = 31,                  /*!< Indicate that the caller is being malicious. */
        AST_CONTROL_UPDATE_RTP_PEER = 32, /*!< Interrupt the bridge and have it update the peer */
        AST_CONTROL_PVT_CAUSE_CODE = 33, /*!< Contains an update to the protocol-specific cause-code stored for branching dials */
+
+       /*
+        * WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
+        *
+        * IAX2 sends these values out over the wire.  To prevent future
+        * incompatibilities, pick the next value in the enum from whatever
+        * is on the current trunk.  If you lose the merge race you need to
+        * fix the previous branches to match what is on trunk.  In addition
+        * you need to change chan_iax2 to explicitly allow the control
+        * frame over the wire if it makes sense for the frame to be passed
+        * to another Asterisk instance.
+        *
+        * WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING WARNING
+        */
 };
 
 enum ast_frame_read_action {