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Improve handling of T.38 re-INVITEs that arrive before a T.38-capable

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application is executing on a channel.

This patch addresses an issue found during working with end-users
using res_fax. If an incoming call is answered in the dialplan, or
jumps to the 'fax' extension due to reception of a CNG tone (with
faxdetect enabled), and then the remote endpoint sends a T.38
re-INVITE, it is possible for the channel's T.38 state to be
'T38_STATE_NEGOTIATING' when the application starts up. Unfortunately,
even if the application wants to use T.38, it can't respond to the
peer's negotiation request, because the AST_CONTROL_T38_PARAMETERS
control frame that chan_sip sent originally has been lost, and the
application needs the content of that frame to be able to formulate a
reply.

This patch adds a new 'request' type to AST_CONTROL_T38_PARAMETERS,
AST_T38_REQUEST_PARMS. If the application sends this request, chan_sip
will re-send the original control frame (with
AST_T38_REQUEST_NEGOTIATE as the request type), and the application
can respond as normal. If this occurs within the five second timeout
in chan_sip, the automatic cancellation of the peer reinvite will be
stopped, and the application will 'own' the negotiation process from
that point onwards.

This also improves the code path in chan_sip to allow sip_indicate(),
when called for AST_CONTROL_T38_PARAMETERS, to be able to return a
non-zero response, which should have been in place before since the
control frame *can* fail to be processed properly. It also modifies
ast_indicate() to return whatever result the channel driver returned
for this control frame, rather than converting all non-zero results
into '-1'. Finally, the new request type intentionally returns a
positive value, so that an application that sends
AST_T38_REQUEST_PARMS can know for certain whether the channel driver
accepted it and will be replying with a control frame of its own, or
whether it was ignored (if the sip_indicate()/ast_indicate() path had
properly supported failure responses before, this would not be
necessary).

This patch also modifies res_fax to take advantage of the new request.

In addition, this patch makes sip_t38_abort() actually lock the
private structure before doing its work... bad programmer, no donut.

This patch also enhances chan_sip's 'faxdetect' support to allow
triggering on T.38 re-INVITEs received as well as CNG tone detection.

Review: https://reviewboard.asterisk.org/r/556/



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@254450 65c4cc65-6c06-0410-ace0-fbb531ad65f3
certified/1.8.6
Kevin P. Fleming 16 years ago
parent 0eb71bccf1
commit 42577406fd
6 changed files with 207 additions and 100 deletions
Show Stats Download Patch File Download Diff File

110
channels/chan_sip.c
Unescape View File

@ -3052,7 +3052,7 @@ static void enable_dsp_detect(struct sip_pvt *p)
} }
} }
if (ast_test_flag(&p->flags[1], SIP_PAGE2_FAX_DETECT)) { if (ast_test_flag(&p->flags[1], SIP_PAGE2_FAX_DETECT_CNG)) {
features |= DSP_FEATURE_FAX_DETECT; features |= DSP_FEATURE_FAX_DETECT;
} }
@ -4163,6 +4163,11 @@ static int sip_call(struct ast_channel *ast, char *dest, int timeout)
res = 0; res = 0;
ast_set_flag(&p->flags[0], SIP_OUTGOING); ast_set_flag(&p->flags[0], SIP_OUTGOING);
/* T.38 re-INVITE FAX detection should never be done for outgoing calls,
* so ensure it is disabled.
*/
ast_clear_flag(&p->flags[1], SIP_PAGE2_FAX_DETECT_T38);
if (p->options->transfer) { if (p->options->transfer) {
char buf[SIPBUFSIZE/2]; char buf[SIPBUFSIZE/2];
@ -5199,22 +5204,24 @@ static int sip_transfer(struct ast_channel *ast, const char *dest)
} }
/*! \brief Helper function which updates T.38 capability information and triggers a reinvite */ /*! \brief Helper function which updates T.38 capability information and triggers a reinvite */
static void interpret_t38_parameters(struct sip_pvt *p, const struct ast_control_t38_parameters *parameters) static int interpret_t38_parameters(struct sip_pvt *p, const struct ast_control_t38_parameters *parameters)
{ {
int res = 0;
if (!ast_test_flag(&p->flags[1], SIP_PAGE2_T38SUPPORT)) { if (!ast_test_flag(&p->flags[1], SIP_PAGE2_T38SUPPORT)) {
return; return -1;
} }
switch (parameters->request_response) { switch (parameters->request_response) {
case AST_T38_NEGOTIATED: case AST_T38_NEGOTIATED:
case AST_T38_REQUEST_NEGOTIATE: /* Request T38 */ case AST_T38_REQUEST_NEGOTIATE: /* Request T38 */
/* Negotiation can not take place without a valid max_ifp value. */ /* Negotiation can not take place without a valid max_ifp value. */
if (!parameters->max_ifp) { if (!parameters->max_ifp) {
change_t38_state(p, T38_DISABLED); change_t38_state(p, T38_DISABLED);
if (p->t38.state == T38_PEER_REINVITE) { if (p->t38.state == T38_PEER_REINVITE) {
AST_SCHED_DEL_UNREF(sched, p->t38id, dialog_unref(p, "when you delete the t38id sched, you should dec the refcount for the stored dialog ptr")); AST_SCHED_DEL_UNREF(sched, p->t38id, dialog_unref(p, "when you delete the t38id sched, you should dec the refcount for the stored dialog ptr"));
transmit_response_reliable(p, "488 Not acceptable here", &p->initreq); transmit_response_reliable(p, "488 Not acceptable here", &p->initreq);
} }
break; break;
} else if (p->t38.state == T38_PEER_REINVITE) { } else if (p->t38.state == T38_PEER_REINVITE) {
AST_SCHED_DEL_UNREF(sched, p->t38id, dialog_unref(p, "when you delete the t38id sched, you should dec the refcount for the stored dialog ptr")); AST_SCHED_DEL_UNREF(sched, p->t38id, dialog_unref(p, "when you delete the t38id sched, you should dec the refcount for the stored dialog ptr"));
p->t38.our_parms = *parameters; p->t38.our_parms = *parameters;
@ -5256,9 +5263,28 @@ static void interpret_t38_parameters(struct sip_pvt *p, const struct ast_control
} else if (p->t38.state == T38_ENABLED) } else if (p->t38.state == T38_ENABLED)
transmit_reinvite_with_sdp(p, FALSE, FALSE); transmit_reinvite_with_sdp(p, FALSE, FALSE);
break; break;
case AST_T38_REQUEST_PARMS: { /* Application wants remote's parameters re-sent */
struct ast_control_t38_parameters parameters = p->t38.their_parms;
if (p->t38.state == T38_PEER_REINVITE) {
AST_SCHED_DEL(sched, p->t38id);
parameters.max_ifp = ast_udptl_get_far_max_ifp(p->udptl);
parameters.request_response = AST_T38_REQUEST_NEGOTIATE;
ast_queue_control_data(p->owner, AST_CONTROL_T38_PARAMETERS, &parameters, sizeof(parameters));
/* we need to return a positive value here, so that applications that
* send this request can determine conclusively whether it was accepted or not...
* older versions of chan_sip would just silently accept it and return zero.
*/
res = AST_T38_REQUEST_PARMS;
}
break;
}
default: default:
res = -1;
break; break;
} }
return res;
} }
/*! \brief Play indication to user /*! \brief Play indication to user
@ -5348,9 +5374,10 @@ static int sip_indicate(struct ast_channel *ast, int condition, const void *data
case AST_CONTROL_T38_PARAMETERS: case AST_CONTROL_T38_PARAMETERS:
if (datalen != sizeof(struct ast_control_t38_parameters)) { if (datalen != sizeof(struct ast_control_t38_parameters)) {
ast_log(LOG_ERROR, "Invalid datalen for AST_CONTROL_T38_PARAMETERS. Expected %d, got %d\n", (int) sizeof(struct ast_control_t38_parameters), (int) datalen); ast_log(LOG_ERROR, "Invalid datalen for AST_CONTROL_T38_PARAMETERS. Expected %d, got %d\n", (int) sizeof(struct ast_control_t38_parameters), (int) datalen);
res = -1;
} else { } else {
const struct ast_control_t38_parameters *parameters = data; const struct ast_control_t38_parameters *parameters = data;
interpret_t38_parameters(p, parameters); res = interpret_t38_parameters(p, parameters);
} }
break; break;
case AST_CONTROL_SRCUPDATE: case AST_CONTROL_SRCUPDATE:
@ -5838,20 +5865,20 @@ static struct ast_frame *sip_read(struct ast_channel *ast)
p->lastrtprx = time(NULL); p->lastrtprx = time(NULL);
/* If we detect a CNG tone and fax detection is enabled then send us off to the fax extension */ /* If we detect a CNG tone and fax detection is enabled then send us off to the fax extension */
if (faxdetected && ast_test_flag(&p->flags[1], SIP_PAGE2_FAX_DETECT)) { if (faxdetected && ast_test_flag(&p->flags[1], SIP_PAGE2_FAX_DETECT_CNG)) {
ast_channel_lock(ast); ast_channel_lock(ast);
if (strcmp(ast->exten, "fax")) { if (strcmp(ast->exten, "fax")) {
const char *target_context = S_OR(ast->macrocontext, ast->context); const char *target_context = S_OR(ast->macrocontext, ast->context);
ast_channel_unlock(ast); ast_channel_unlock(ast);
if (ast_exists_extension(ast, target_context, "fax", 1, ast->cid.cid_num)) { if (ast_exists_extension(ast, target_context, "fax", 1, ast->cid.cid_num)) {
ast_verbose(VERBOSE_PREFIX_2 "Redirecting '%s' to fax extension\n", ast->name); ast_verbose(VERBOSE_PREFIX_2 "Redirecting '%s' to fax extension due to CNG detection\n", ast->name);
pbx_builtin_setvar_helper(ast, "FAXEXTEN", ast->exten); pbx_builtin_setvar_helper(ast, "FAXEXTEN", ast->exten);
if (ast_async_goto(ast, target_context, "fax", 1)) { if (ast_async_goto(ast, target_context, "fax", 1)) {
ast_log(LOG_NOTICE, "Failed to async goto '%s' into fax of '%s'\n", ast->name, target_context); ast_log(LOG_NOTICE, "Failed to async goto '%s' into fax of '%s'\n", ast->name, target_context);
} }
fr = &ast_null_frame; fr = &ast_null_frame;
} else { } else {
ast_log(LOG_NOTICE, "Fax detected but no fax extension\n"); ast_log(LOG_NOTICE, "FAX CNG detected but no fax extension\n");
} }
} else { } else {
ast_channel_unlock(ast); ast_channel_unlock(ast);
@ -7154,6 +7181,25 @@ static int process_sdp(struct sip_pvt *p, struct sip_request *req, int t38action
} else if ((t38action == SDP_T38_INITIATE) && } else if ((t38action == SDP_T38_INITIATE) &&
p->owner && p->lastinvite) { p->owner && p->lastinvite) {
change_t38_state(p, T38_PEER_REINVITE); /* T38 Offered in re-invite from remote party */ change_t38_state(p, T38_PEER_REINVITE); /* T38 Offered in re-invite from remote party */
/* If fax detection is enabled then send us off to the fax extension */
if (ast_test_flag(&p->flags[1], SIP_PAGE2_FAX_DETECT_T38)) {
ast_channel_lock(p->owner);
if (strcmp(p->owner->exten, "fax")) {
const char *target_context = S_OR(p->owner->macrocontext, p->owner->context);
ast_channel_unlock(p->owner);
if (ast_exists_extension(p->owner, target_context, "fax", 1, p->owner->cid.cid_num)) {
ast_verbose(VERBOSE_PREFIX_2 "Redirecting '%s' to fax extension due to peer T.38 re-INVITE\n", p->owner->name);
pbx_builtin_setvar_helper(p->owner, "FAXEXTEN", p->owner->exten);
if (ast_async_goto(p->owner, target_context, "fax", 1)) {
ast_log(LOG_NOTICE, "Failed to async goto '%s' into fax of '%s'\n", p->owner->name, target_context);
}
} else {
ast_log(LOG_NOTICE, "T.38 re-INVITE detected but no fax extension\n");
}
} else {
ast_channel_unlock(p->owner);
}
}
} }
} else { } else {
ast_udptl_stop(p->udptl); ast_udptl_stop(p->udptl);
@ -18825,15 +18871,24 @@ static int do_magic_pickup(struct ast_channel *channel, const char *extension, c
return 0; return 0;
} }
/*! \brief Called to deny a T38 reinvite if the core does not respond to our request */
static int sip_t38_abort(const void *data) static int sip_t38_abort(const void *data)
{ {
struct sip_pvt *p = (struct sip_pvt *) data; struct sip_pvt *p = (struct sip_pvt *) data;
change_t38_state(p, T38_DISABLED); sip_pvt_lock(p);
transmit_response_reliable(p, "488 Not acceptable here", &p->initreq); /* an application may have taken ownership of the T.38 negotiation on this
p->t38id = -1; * channel while we were waiting to grab the lock... if it did, the scheduler
dialog_unref(p, "unref the dialog ptr from sip_t38_abort, because it held a dialog ptr"); * id will have been reset to -1, which is our indication that we do *not*
* want to abort the negotiation process
*/
if (p->t38id != -1) {
change_t38_state(p, T38_DISABLED);
transmit_response_reliable(p, "488 Not acceptable here", &p->initreq);
p->t38id = -1;
dialog_unref(p, "unref the dialog ptr from sip_t38_abort, because it held a dialog ptr");
}
sip_pvt_unlock(p);
return 0; return 0;
} }
@ -22603,7 +22658,24 @@ static int handle_common_options(struct ast_flags *flags, struct ast_flags *mask
ast_set2_flag(&flags[1], ast_true(v->value), SIP_PAGE2_IGNORESDPVERSION); ast_set2_flag(&flags[1], ast_true(v->value), SIP_PAGE2_IGNORESDPVERSION);
} else if (!strcasecmp(v->name, "faxdetect")) { } else if (!strcasecmp(v->name, "faxdetect")) {
ast_set_flag(&mask[1], SIP_PAGE2_FAX_DETECT); ast_set_flag(&mask[1], SIP_PAGE2_FAX_DETECT);
ast_set2_flag(&flags[1], ast_true(v->value), SIP_PAGE2_FAX_DETECT); if (ast_true(v->value)) {
ast_set_flag(&flags[1], SIP_PAGE2_FAX_DETECT_BOTH);
} else if (ast_false(v->value)) {
ast_clear_flag(&flags[1], SIP_PAGE2_FAX_DETECT_BOTH);
} else {
char *buf = ast_strdupa(v->value);
char *word, *next = buf;
while ((word = strsep(&next, ","))) {
if (!strcasecmp(word, "cng")) {
ast_set_flag(&flags[1], SIP_PAGE2_FAX_DETECT_CNG);
} else if (!strcasecmp(word, "t38")) {
ast_set_flag(&flags[1], SIP_PAGE2_FAX_DETECT_T38);
} else {
ast_log(LOG_WARNING, "Unknown faxdetect mode '%s' on line %d.\n", word, v->lineno);
}
}
}
} else if (!strcasecmp(v->name, "rfc2833compensate")) { } else if (!strcasecmp(v->name, "rfc2833compensate")) {
ast_set_flag(&mask[1], SIP_PAGE2_RFC2833_COMPENSATE); ast_set_flag(&mask[1], SIP_PAGE2_RFC2833_COMPENSATE);
ast_set2_flag(&flags[1], ast_true(v->value), SIP_PAGE2_RFC2833_COMPENSATE); ast_set2_flag(&flags[1], ast_true(v->value), SIP_PAGE2_RFC2833_COMPENSATE);

78
channels/sip/include/sip.h
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@ -302,43 +302,47 @@
a second page of flags (for flags[1] */ a second page of flags (for flags[1] */
/*@{*/ /*@{*/
/* realtime flags */ /* realtime flags */
#define SIP_PAGE2_RTCACHEFRIENDS (1 << 0) /*!< GP: Should we keep RT objects in memory for extended time? */ #define SIP_PAGE2_RTCACHEFRIENDS (1 << 0) /*!< GP: Should we keep RT objects in memory for extended time? */
#define SIP_PAGE2_RTAUTOCLEAR (1 << 2) /*!< GP: Should we clean memory from peers after expiry? */ #define SIP_PAGE2_RTAUTOCLEAR (1 << 1) /*!< GP: Should we clean memory from peers after expiry? */
#define SIP_PAGE2_RPID_UPDATE (1 << 3) #define SIP_PAGE2_RPID_UPDATE (1 << 2)
#define SIP_PAGE2_Q850_REASON (1 << 4) /*!< DP: Get/send cause code via Reason header */ #define SIP_PAGE2_Q850_REASON (1 << 3) /*!< DP: Get/send cause code via Reason header */
/* Space for addition of other realtime flags in the future */ #define SIP_PAGE2_SYMMETRICRTP (1 << 4) /*!< GDP: Whether symmetric RTP is enabled or not */
#define SIP_PAGE2_SYMMETRICRTP (1 << 8) /*!< GDP: Whether symmetric RTP is enabled or not */ #define SIP_PAGE2_STATECHANGEQUEUE (1 << 5) /*!< D: Unsent state pending change exists */
#define SIP_PAGE2_STATECHANGEQUEUE (1 << 9) /*!< D: Unsent state pending change exists */
#define SIP_PAGE2_CONNECTLINEUPDATE_PEND (1 << 6)
#define SIP_PAGE2_CONNECTLINEUPDATE_PEND (1 << 10) #define SIP_PAGE2_RPID_IMMEDIATE (1 << 7)
#define SIP_PAGE2_RPID_IMMEDIATE (1 << 11) #define SIP_PAGE2_RPORT_PRESENT (1 << 8) /*!< Was rport received in the Via header? */
#define SIP_PAGE2_RPORT_PRESENT (1 << 12) /*!< Was rport received in the Via header? */ #define SIP_PAGE2_PREFERRED_CODEC (1 << 9) /*!< GDP: Only respond with single most preferred joint codec */
#define SIP_PAGE2_PREFERRED_CODEC (1 << 13) /*!< GDP: Only respond with single most preferred joint codec */ #define SIP_PAGE2_VIDEOSUPPORT (1 << 10) /*!< DP: Video supported if offered? */
#define SIP_PAGE2_VIDEOSUPPORT (1 << 14) /*!< DP: Video supported if offered? */ #define SIP_PAGE2_TEXTSUPPORT (1 << 11) /*!< GDP: Global text enable */
#define SIP_PAGE2_TEXTSUPPORT (1 << 15) /*!< GDP: Global text enable */ #define SIP_PAGE2_ALLOWSUBSCRIBE (1 << 12) /*!< GP: Allow subscriptions from this peer? */
#define SIP_PAGE2_ALLOWSUBSCRIBE (1 << 16) /*!< GP: Allow subscriptions from this peer? */ #define SIP_PAGE2_ALLOWOVERLAP (1 << 13) /*!< DP: Allow overlap dialing ? */
#define SIP_PAGE2_ALLOWOVERLAP (1 << 17) /*!< DP: Allow overlap dialing ? */ #define SIP_PAGE2_SUBSCRIBEMWIONLY (1 << 14) /*!< GP: Only issue MWI notification if subscribed to */
#define SIP_PAGE2_SUBSCRIBEMWIONLY (1 << 18) /*!< GP: Only issue MWI notification if subscribed to */ #define SIP_PAGE2_IGNORESDPVERSION (1 << 15) /*!< GDP: Ignore the SDP session version number we receive and treat all sessions as new */
#define SIP_PAGE2_IGNORESDPVERSION (1 << 19) /*!< GDP: Ignore the SDP session version number we receive and treat all sessions as new */
#define SIP_PAGE2_T38SUPPORT (3 << 16) /*!< GDP: T.38 Fax Support */
#define SIP_PAGE2_T38SUPPORT (3 << 20) /*!< GDP: T.38 Fax Support */ #define SIP_PAGE2_T38SUPPORT_UDPTL (1 << 16) /*!< GDP: T.38 Fax Support (no error correction) */
#define SIP_PAGE2_T38SUPPORT_UDPTL (1 << 20) /*!< GDP: T.38 Fax Support (no error correction) */ #define SIP_PAGE2_T38SUPPORT_UDPTL_FEC (2 << 16) /*!< GDP: T.38 Fax Support (FEC error correction) */
#define SIP_PAGE2_T38SUPPORT_UDPTL_FEC (2 << 20) /*!< GDP: T.38 Fax Support (FEC error correction) */ #define SIP_PAGE2_T38SUPPORT_UDPTL_REDUNDANCY (3 << 16) /*!< GDP: T.38 Fax Support (redundancy error correction) */
#define SIP_PAGE2_T38SUPPORT_UDPTL_REDUNDANCY (3 << 20) /*!< GDP: T.38 Fax Support (redundancy error correction) */
#define SIP_PAGE2_CALL_ONHOLD (3 << 18) /*!< D: Call hold states: */
#define SIP_PAGE2_CALL_ONHOLD (3 << 23) /*!< D: Call hold states: */ #define SIP_PAGE2_CALL_ONHOLD_ACTIVE (1 << 18) /*!< D: Active hold */
#define SIP_PAGE2_CALL_ONHOLD_ACTIVE (1 << 23) /*!< D: Active hold */ #define SIP_PAGE2_CALL_ONHOLD_ONEDIR (2 << 18) /*!< D: One directional hold */
#define SIP_PAGE2_CALL_ONHOLD_ONEDIR (2 << 23) /*!< D: One directional hold */ #define SIP_PAGE2_CALL_ONHOLD_INACTIVE (3 << 18) /*!< D: Inactive hold */
#define SIP_PAGE2_CALL_ONHOLD_INACTIVE (3 << 23) /*!< D: Inactive hold */
#define SIP_PAGE2_RFC2833_COMPENSATE (1 << 20) /*!< DP: Compensate for buggy RFC2833 implementations */
#define SIP_PAGE2_RFC2833_COMPENSATE (1 << 25) /*!< DP: Compensate for buggy RFC2833 implementations */ #define SIP_PAGE2_BUGGY_MWI (1 << 21) /*!< DP: Buggy CISCO MWI fix */
#define SIP_PAGE2_BUGGY_MWI (1 << 26) /*!< DP: Buggy CISCO MWI fix */ #define SIP_PAGE2_DIALOG_ESTABLISHED (1 << 22) /*!< 29: Has a dialog been established? */
#define SIP_PAGE2_DIALOG_ESTABLISHED (1 << 27) /*!< 29: Has a dialog been established? */
#define SIP_PAGE2_FAX_DETECT (1 << 28) /*!< DP: Fax Detection support */ #define SIP_PAGE2_FAX_DETECT (3 << 23) /*!< DP: Fax Detection support */
#define SIP_PAGE2_REGISTERTRYING (1 << 29) /*!< DP: Send 100 Trying on REGISTER attempts */ #define SIP_PAGE2_FAX_DETECT_CNG (1 << 23) /*!< DP: Fax Detection support - detect CNG in audio */
#define SIP_PAGE2_UDPTL_DESTINATION (1 << 30) /*!< DP: Use source IP of RTP as destination if NAT is enabled */ #define SIP_PAGE2_FAX_DETECT_T38 (2 << 23) /*!< DP: Fax Detection support - detect T.38 reinvite from peer */
#define SIP_PAGE2_VIDEOSUPPORT_ALWAYS (1 << 31) /*!< DP: Always set up video, even if endpoints don't support it */ #define SIP_PAGE2_FAX_DETECT_BOTH (3 << 23) /*!< DP: Fax Detection support - detect both */
#define SIP_PAGE2_REGISTERTRYING (1 << 24) /*!< DP: Send 100 Trying on REGISTER attempts */
#define SIP_PAGE2_UDPTL_DESTINATION (1 << 25) /*!< DP: Use source IP of RTP as destination if NAT is enabled */
#define SIP_PAGE2_VIDEOSUPPORT_ALWAYS (1 << 26) /*!< DP: Always set up video, even if endpoints don't support it */
#define SIP_PAGE2_FLAGS_TO_COPY \ #define SIP_PAGE2_FLAGS_TO_COPY \
(SIP_PAGE2_ALLOWSUBSCRIBE | SIP_PAGE2_ALLOWOVERLAP | SIP_PAGE2_IGNORESDPVERSION | \ (SIP_PAGE2_ALLOWSUBSCRIBE | SIP_PAGE2_ALLOWOVERLAP | SIP_PAGE2_IGNORESDPVERSION | \

8
configs/sip.conf.sample
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@ -533,9 +533,13 @@ srvlookup=yes ; Enable DNS SRV lookups on outbound calls
; ; send 400 byte T.38 FAX packets to it. ; ; send 400 byte T.38 FAX packets to it.
; ;
; FAX detection will cause the SIP channel to jump to the 'fax' extension (if it exists) ; FAX detection will cause the SIP channel to jump to the 'fax' extension (if it exists)
; when a CNG tone is detected on an incoming call. ; based one or more events being detected. The events that can be detected are an incoming
; CNG tone or an incoming T.38 re-INVITE request.
; ;
; faxdetect = yes ; Default false ; faxdetect = yes ; Default 'no', 'yes' enables both CNG and T.38 detection
; faxdetect = cng ; Enables only CNG detection
; faxdetect = t38 ; Enables only T.38 detection
; faxdetect = both ; Enables both CNG and T.38 detection (same as 'yes')
; ;
;----------------------------------------- OUTBOUND SIP REGISTRATIONS ------------------------ ;----------------------------------------- OUTBOUND SIP REGISTRATIONS ------------------------
; Asterisk can register as a SIP user agent to a SIP proxy (provider) ; Asterisk can register as a SIP user agent to a SIP proxy (provider)

3
include/asterisk/frame.h
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@ -332,7 +332,8 @@ enum ast_control_t38 {
AST_T38_REQUEST_TERMINATE, /*!< Terminate T38 on a channel (fax to voice) */ AST_T38_REQUEST_TERMINATE, /*!< Terminate T38 on a channel (fax to voice) */
AST_T38_NEGOTIATED, /*!< T38 negotiated (fax mode) */ AST_T38_NEGOTIATED, /*!< T38 negotiated (fax mode) */
AST_T38_TERMINATED, /*!< T38 terminated (back to voice) */ AST_T38_TERMINATED, /*!< T38 terminated (back to voice) */
AST_T38_REFUSED /*!< T38 refused for some reason (usually rejected by remote end) */ AST_T38_REFUSED, /*!< T38 refused for some reason (usually rejected by remote end) */
AST_T38_REQUEST_PARMS, /*!< request far end T.38 parameters for a channel in 'negotiating' state */
}; };
enum ast_control_t38_rate { enum ast_control_t38_rate {

7
main/channel.c
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@ -3715,9 +3715,10 @@ int ast_indicate_data(struct ast_channel *chan, int _condition,
* control frames, so we need to return failure, but there * control frames, so we need to return failure, but there
* is also no value in the log message below being emitted * is also no value in the log message below being emitted
* since failure to handle these frames is not an 'error' * since failure to handle these frames is not an 'error'
* so just return right now. * so just return right now. in addition, we want to return
*/ * whatever value the channel driver returned, in case it
return -1; * has some meaning.*/
return res;
case AST_CONTROL_RINGING: case AST_CONTROL_RINGING:
ts = ast_get_indication_tone(chan->zone, "ring"); ts = ast_get_indication_tone(chan->zone, "ring");
/* It is common practice for channel drivers to return -1 if trying /* It is common practice for channel drivers to return -1 if trying

101
res/res_fax.c
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@ -654,6 +654,7 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
struct ast_channel *c = chan; struct ast_channel *c = chan;
unsigned int orig_write_format = 0, orig_read_format = 0; unsigned int orig_write_format = 0, orig_read_format = 0;
unsigned int request_t38 = 0; unsigned int request_t38 = 0;
unsigned int send_audio = 1;
details->our_t38_parameters.version = 0; details->our_t38_parameters.version = 0;
details->our_t38_parameters.max_ifp = 400; details->our_t38_parameters.max_ifp = 400;
@ -662,8 +663,57 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
chancount = 1; chancount = 1;
/* generate 3 seconds of CED if we are in receive mode */ switch ((t38_state = ast_channel_get_t38_state(chan))) {
if (details->caps & AST_FAX_TECH_RECEIVE) { case T38_STATE_UNKNOWN:
if (details->caps & AST_FAX_TECH_SEND) {
if (details->option.allow_audio) {
details->caps |= AST_FAX_TECH_AUDIO;
} else {
/* we are going to send CNG to attempt to stimulate the receiver
* into switching to T.38, since audio mode is not allowed
*/
send_cng = 0;
}
} else {
/* we *always* request a switch to T.38 if allowed; if audio is also
* allowed, then we will allow the switch to happen later if needed
*/
if (details->option.allow_audio) {
details->caps |= AST_FAX_TECH_AUDIO;
}
request_t38 = 1;
}
details->caps |= AST_FAX_TECH_T38;
break;
case T38_STATE_UNAVAILABLE:
details->caps |= AST_FAX_TECH_AUDIO;
break;
case T38_STATE_NEGOTIATING: {
/* the other end already sent us a T.38 reinvite, so we need to prod the channel
* driver into resending their parameters to us if it supports doing so... if
* not, we can't proceed, because we can't create a proper reply without them.
* if it does work, the channel driver will send an AST_CONTROL_T38_PARAMETERS
* with a request of AST_T38_REQUEST_NEGOTIATE, which will be read by the function
* that gets called after this one completes
*/
struct ast_control_t38_parameters parameters = { .request_response = AST_T38_REQUEST_PARMS, };
ast_log(LOG_NOTICE, "Channel is already in T.38 negotiation state; retrieving remote parameters.\n");
if (ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &parameters, sizeof(parameters)) != AST_T38_REQUEST_PARMS) {
ast_log(LOG_ERROR, "channel '%s' is in an unsupported T.38 negotiation state, cannot continue.\n", chan->name);
return -1;
}
details->caps |= AST_FAX_TECH_T38;
details->option.allow_audio = 0;
send_audio = 0;
break;
}
default:
ast_log(LOG_ERROR, "channel '%s' is in an unsupported T.38 negotiation state, cannot continue.\n", chan->name);
return -1;
}
/* generate 3 seconds of CED if we are in receive mode and not already negotiating T.38 */
if (send_audio && (details->caps & AST_FAX_TECH_RECEIVE)) {
ms = 3000; ms = 3000;
if (ast_tonepair_start(chan, 2100, 0, ms, 0)) { if (ast_tonepair_start(chan, 2100, 0, ms, 0)) {
ast_log(LOG_ERROR, "error generating CED tone on %s\n", chan->name); ast_log(LOG_ERROR, "error generating CED tone on %s\n", chan->name);
@ -719,36 +769,6 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
ast_tonepair_stop(chan); ast_tonepair_stop(chan);
} }
switch ((t38_state = ast_channel_get_t38_state(chan))) {
case T38_STATE_UNKNOWN:
if (details->caps & AST_FAX_TECH_SEND) {
if (details->option.allow_audio) {
details->caps |= AST_FAX_TECH_AUDIO;
} else {
/* we are going to send CNG to attempt to stimulate the receiver
* into switching to T.38, since audio mode is not allowed
*/
send_cng = 0;
}
} else {
/* we *always* request a switch to T.38 if allowed; if audio is also
* allowed, then we will allow the switch to happen later if needed
*/
if (details->option.allow_audio) {
details->caps |= AST_FAX_TECH_AUDIO;
}
request_t38 = 1;
}
details->caps |= AST_FAX_TECH_T38;
break;
case T38_STATE_UNAVAILABLE:
details->caps |= AST_FAX_TECH_AUDIO;
break;
default:
ast_log(LOG_ERROR, "channel '%s' is in an unsupported T.38 negotiation state, cannot continue.\n", chan->name);
return -1;
}
if (request_t38) { if (request_t38) {
/* wait up to five seconds for negotiation to complete */ /* wait up to five seconds for negotiation to complete */
timeout = 5000; timeout = 5000;
@ -772,19 +792,23 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
if (request_t38 || !details->option.allow_audio) { if (request_t38 || !details->option.allow_audio) {
struct ast_silence_generator *silence_gen = NULL; struct ast_silence_generator *silence_gen = NULL;
if (send_cng != -1) { if (send_audio && (send_cng != -1)) {
silence_gen = ast_channel_start_silence_generator(chan); silence_gen = ast_channel_start_silence_generator(chan);
} }
while (timeout > 0) { while (timeout > 0) {
if (send_cng > 3000) { if (send_cng > 3000) {
ast_channel_stop_silence_generator(chan, silence_gen); if (send_audio) {
silence_gen = NULL; ast_channel_stop_silence_generator(chan, silence_gen);
ast_tonepair_start(chan, 1100, 0, 500, 0); silence_gen = NULL;
ast_tonepair_start(chan, 1100, 0, 500, 0);
}
send_cng = 0; send_cng = 0;
} else if (!chan->generator && (send_cng != -1)) { } else if (!chan->generator && (send_cng != -1)) {
/* The CNG tone is done so restart silence generation. */ if (send_audio) {
silence_gen = ast_channel_start_silence_generator(chan); /* The CNG tone is done so restart silence generation. */
silence_gen = ast_channel_start_silence_generator(chan);
}
} }
/* this timeout *MUST* be 500ms, in order to keep the spacing /* this timeout *MUST* be 500ms, in order to keep the spacing
* of CNG tones correct when this loop is sending them * of CNG tones correct when this loop is sending them
@ -828,6 +852,7 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
t38_parameters.request_response = AST_T38_NEGOTIATED; t38_parameters.request_response = AST_T38_NEGOTIATED;
ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &t38_parameters, sizeof(t38_parameters)); ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &t38_parameters, sizeof(t38_parameters));
stop = 0; stop = 0;
send_audio = 0;
break; break;
case AST_T38_NEGOTIATED: case AST_T38_NEGOTIATED:
ast_log(LOG_NOTICE, "Negotiated T.38 for %s on %s\n", (details->caps & AST_FAX_TECH_SEND) ? "send" : "receive", chan->name); ast_log(LOG_NOTICE, "Negotiated T.38 for %s on %s\n", (details->caps & AST_FAX_TECH_SEND) ? "send" : "receive", chan->name);

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