1 files changed, 85 insertions, 47 deletions

diff --git a/res/res_fax.c b/res/res_fax.c
index 431e7086a..8073f2d6e 100644
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -53,6 +53,10 @@
  * \ingroup applications
  */
 
+/*** MODULEINFO
+	<support_level>core</support_level>
+ ***/
+
 #include "asterisk.h"
 
 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
@@ -253,6 +257,8 @@ struct fax_gateway {
 	int framehook;
 	/*! \brief bridged */
 	int bridged:1;
+	/*! \brief 1 if a v21 preamble has been detected */
+	int detected_v21:1;
 	/*! \brief a flag to track the state of our negotiation */
 	enum ast_t38_state t38_state;
 	/*! \brief original audio formats */
@@ -2407,10 +2413,10 @@ static struct fax_gateway *fax_gateway_new(struct ast_fax_session_details *detai
 	gateway->framehook = -1;
 
 	ast_dsp_set_features(gateway->chan_dsp, DSP_FEATURE_FAX_DETECT);
-	ast_dsp_set_faxmode(gateway->chan_dsp, DSP_FAXMODE_DETECT_CED);
+	ast_dsp_set_faxmode(gateway->chan_dsp, DSP_FAXMODE_DETECT_V21);
 
 	ast_dsp_set_features(gateway->peer_dsp, DSP_FEATURE_FAX_DETECT);
-	ast_dsp_set_faxmode(gateway->peer_dsp, DSP_FAXMODE_DETECT_CED);
+	ast_dsp_set_faxmode(gateway->peer_dsp, DSP_FAXMODE_DETECT_V21);
 
 	details->caps = AST_FAX_TECH_GATEWAY;
 	if (!(gateway->s = fax_session_reserve(details, &gateway->token))) {
@@ -2465,57 +2471,68 @@ static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session
 	return 0;
 }
 
-static struct ast_frame *fax_gateway_detect_ced(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
+static struct ast_frame *fax_gateway_request_t38(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_frame *f)
 {
-	struct ast_frame *dfr = ast_frdup(f);
-	struct ast_dsp *active_dsp = (active == chan) ? gateway->chan_dsp : gateway->peer_dsp;
-	struct ast_channel *other = (active == chan) ? peer : chan;
+	struct ast_frame *fp;
+	struct ast_control_t38_parameters t38_parameters = {
+		.request_response = AST_T38_REQUEST_NEGOTIATE,
+	};
+	struct ast_frame control_frame = {
+		.src = "res_fax",
+		.frametype = AST_FRAME_CONTROL,
+		.datalen = sizeof(t38_parameters),
+		.subclass.integer = AST_CONTROL_T38_PARAMETERS,
+		.data.ptr = &t38_parameters,
+	};
 
-	if (!dfr) {
+	struct ast_fax_session_details *details = find_details(chan);
+
+	if (!details) {
+		ast_log(LOG_ERROR, "no FAX session details found on chan %s for T.38 gateway session, odd\n", chan->name);
+		ast_framehook_detach(chan, gateway->framehook);
 		return f;
 	}
 
-	if (!(dfr = ast_dsp_process(active, active_dsp, dfr))) {
+	t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
+	ao2_ref(details, -1);
+
+	if (!(fp = ast_frisolate(&control_frame))) {
+		ast_log(LOG_ERROR, "error generating T.38 request control frame on chan %s for T.38 gateway session\n", chan->name);
 		return f;
 	}
 
-	if (dfr->frametype == AST_FRAME_DTMF && dfr->subclass.integer == 'e') {
-		if (ast_channel_get_t38_state(other) == T38_STATE_UNKNOWN) {
-			struct ast_control_t38_parameters t38_parameters = {
-				.request_response = AST_T38_REQUEST_NEGOTIATE,
-			};
-			struct ast_frame control_frame = {
-				.src = "res_fax",
-				.frametype = AST_FRAME_CONTROL,
-				.datalen = sizeof(t38_parameters),
-				.subclass.integer = AST_CONTROL_T38_PARAMETERS,
-				.data.ptr = &t38_parameters,
-			};
+	gateway->t38_state = T38_STATE_NEGOTIATING;
+	gateway->timeout_start = ast_tvnow();
 
-			struct ast_fax_session_details *details = find_details(chan);
-			ast_frfree(dfr);
+	ast_debug(1, "requesting T.38 for gateway session for %s\n", chan->name);
+	return fp;
+}
 
-			if (!details) {
-				ast_log(LOG_ERROR, "no FAX session details found on chan %s for T.38 gateway session, odd\n", chan->name);
-				ast_framehook_detach(chan, gateway->framehook);
-				return f;
-			}
+static struct ast_frame *fax_gateway_detect_v21(struct fax_gateway *gateway, struct ast_channel *chan, struct ast_channel *peer, struct ast_channel *active, struct ast_frame *f)
+{
+	struct ast_frame *dfr = ast_frdup(f);
+	struct ast_dsp *active_dsp = (active == chan) ? gateway->chan_dsp : gateway->peer_dsp;
+	struct ast_channel *other = (active == chan) ? peer : chan;
 
-			t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
-			ao2_ref(details, -1);
+	if (gateway->detected_v21) {
+		return f;
+	}
 
-			if (!(dfr = ast_frisolate(&control_frame))) {
-				ast_log(LOG_ERROR, "error generating T.38 request control frame on chan %s for T.38 gateway session\n", chan->name);
-				return f;
-			}
+	if (!dfr) {
+		return f;
+	}
 
-			gateway->t38_state = T38_STATE_NEGOTIATING;
-			gateway->timeout_start = ast_tvnow();
+	if (!(dfr = ast_dsp_process(active, active_dsp, dfr))) {
+		return f;
+	}
 
-			ast_debug(1, "detected CED tone on %s, requesting T.38 on %s for T.38 gateway session\n", active->name, other->name);
-			return dfr;
+	if (dfr->frametype == AST_FRAME_DTMF && dfr->subclass.integer == 'g') {
+		gateway->detected_v21 = 1;
+		if (ast_channel_get_t38_state(other) == T38_STATE_UNKNOWN) {
+			ast_debug(1, "detected v21 preamble from %s\n", active->name);
+			return fax_gateway_request_t38(gateway, chan, f);
 		} else {
-			ast_debug(1, "detected CED tone on %s, but %s does not support T.38 for T.38 gateway session\n", active->name, other->name);
+			ast_debug(1, "detected v21 preamble on %s, but %s does not support T.38 for T.38 gateway session\n", active->name, other->name);
 		}
 	}
 
@@ -2568,6 +2585,7 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
 
 	if (control_params->request_response == AST_T38_REQUEST_NEGOTIATE) {
 		enum ast_t38_state state = ast_channel_get_t38_state(other);
+
 		if (state == T38_STATE_UNKNOWN) {
 			/* we detected a request to negotiate T.38 and the
 			 * other channel appears to support T.38, we'll pass
@@ -2607,7 +2625,7 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
 			return &ast_null_frame;
 		} else if (gateway->t38_state == T38_STATE_NEGOTIATING) {
 			/* we got a request to negotiate T.38 after we already
-			 * sent one to the other party based on CED tone
+			 * sent one to the other party based on v21 preamble
 			 * detection. We'll just pretend we passed this request
 			 * through in the first place. */
 
@@ -2615,12 +2633,12 @@ static struct ast_frame *fax_gateway_detect_t38(struct fax_gateway *gateway, str
 			gateway->t38_state = T38_STATE_UNKNOWN;
 			gateway->timeout_start = ast_tvnow();
 
-			ast_debug(1, "%s is attempting to negotiate T.38 after we already sent a negotiation request based on CED detection\n", active->name);
+			ast_debug(1, "%s is attempting to negotiate T.38 after we already sent a negotiation request based on v21 preamble detection\n", active->name);
 			ao2_ref(details, -1);
 			return &ast_null_frame;
 		} else if (gateway->t38_state == T38_STATE_NEGOTIATED) {
 			/* we got a request to negotiate T.38 after we already
-			 * sent one to the other party based on CED tone
+			 * sent one to the other party based on v21 preamble
 			 * detection and received a response. We need to
 			 * respond to this and shut down the gateway. */
 
@@ -2841,7 +2859,8 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
 
 		gateway->timeout_start = ast_tvnow();
 
-		/* we are bridged, change r/w formats to SLIN for CED detection and T.30 */
+		/* we are bridged, change r/w formats to SLIN for v21 preamble
+		 * detection and T.30 */
 		ast_format_copy(&gateway->chan_read_format, &chan->readformat);
 		ast_format_copy(&gateway->chan_write_format, &chan->readformat);
 
@@ -2916,16 +2935,16 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
 		return fax_gateway_detect_t38(gateway, chan, peer, active, f);
 	}
 
-	/* not in gateway mode yet, listen for CED */
-	/* XXX this should detect a v21 preamble instead of CED */
-	if (gateway->t38_state == T38_STATE_UNAVAILABLE && f->frametype == AST_FRAME_VOICE) {
-		return fax_gateway_detect_ced(gateway, chan, peer, active, f);
+	if (!gateway->detected_v21 && gateway->t38_state == T38_STATE_UNAVAILABLE && f->frametype == AST_FRAME_VOICE) {
+		/* not in gateway mode and have not detected v21 yet, listen
+		 * for v21 */
+		return fax_gateway_detect_v21(gateway, chan, peer, active, f);
 	}
 
 	/* in gateway mode, gateway some packets */
 	if (gateway->t38_state == T38_STATE_NEGOTIATED) {
 		/* framehooks are called in __ast_read() before frame format
-		 * translation is does, so we need to translate here */
+		 * translation is done, so we need to translate here */
 		if ((f->frametype == AST_FRAME_VOICE) && (f->subclass.format.id != AST_FORMAT_SLINEAR)) {
 			if (active->readtrans && (f = ast_translate(active->readtrans, f, 1)) == NULL) {
 				f = &ast_null_frame;
@@ -2942,6 +2961,25 @@ static struct ast_frame *fax_gateway_framehook(struct ast_channel *chan, struct
 		return f;
 	}
 
+	/* force silence on the line if T.38 negotiation might be taking place */
+	if (gateway->t38_state != T38_STATE_UNAVAILABLE && gateway->t38_state != T38_STATE_REJECTED) {
+		if (f->frametype == AST_FRAME_VOICE && f->subclass.format.id == AST_FORMAT_SLINEAR) {
+			short silence_buf[f->samples];
+			struct ast_frame silence_frame = {
+				.frametype = AST_FRAME_VOICE,
+				.data.ptr = silence_buf,
+				.samples = f->samples,
+				.datalen = sizeof(silence_buf),
+			};
+			ast_format_set(&silence_frame.subclass.format, AST_FORMAT_SLINEAR, 0);
+			memset(silence_buf, 0, sizeof(silence_buf));
+
+			return ast_frisolate(&silence_frame);
+		} else {
+			return &ast_null_frame;
+		}
+	}
+
 	return f;
 }