res_fax: Add T.38 negotiation timeout option

This change makes the T.38 negotiation timeout configurable via
't38timeout' in res_fax.conf or FAXOPT(t38timeout). It was previously
hard coded to be 5000 milliseconds.

This change also handles T.38 switch failures by aborting the fax since
in the case where this can happen, both sides have agreed to switch to
T.38 and Asterisk is unable to do so.

Review: https://reviewboard.asterisk.org/r/4320/
........

Merged revisions 430415 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/13@430416 65c4cc65-6c06-0410-ace0-fbb531ad65f3

4 files changed, 55 insertions, 3 deletions

diff --git a/CHANGES b/CHANGES
index c200550ad..8762dc77c 100644
--- a/CHANGES
+++ b/CHANGES
@@ -39,6 +39,13 @@ res_pjsip_config_wizard
    can be found in the sample configuration file at
    config/samples/pjsip_wizard.conf.sample.
 
+res_fax
+-----------
+ * The T.38 negotiation timeout was previously hard coded at 5000 milliseconds
+   and is now configurable via the 't38timeout' configuration option in
+   res_fax.conf and via the fax options dialplan function 'FAXOPT(t38timeout)'.
+   The default remains at 5000 milliseconds.
+
 ARI
 ------------------
  * The Originate operation now takes in an originator channel. The linked ID of
diff --git a/configs/samples/res_fax.conf.sample b/configs/samples/res_fax.conf.sample
index dfaa4ce93..022a23aad 100644
--- a/configs/samples/res_fax.conf.sample
+++ b/configs/samples/res_fax.conf.sample
@@ -26,3 +26,7 @@ statusevents=yes
 ; Enable/disable T.30 ECM (error correction mode) by default.
 ; Default: Enabled
 ;ecm=yes
+
+; T.38 Negotiation Timeout in milliseconds
+; Default: 5000
+t38timeout=5000
diff --git a/include/asterisk/res_fax.h b/include/asterisk/res_fax.h
index b0a1a221b..746518b95 100644
--- a/include/asterisk/res_fax.h
+++ b/include/asterisk/res_fax.h
@@ -175,6 +175,8 @@ struct ast_fax_session_details {
 	struct ast_fax_t38_parameters our_t38_parameters;
 	/*! the other endpoint's T.38 session parameters, if any */
 	struct ast_fax_t38_parameters their_t38_parameters;
+	/*! T.38 negotiation in ms */
+	unsigned int t38timeout;
 	/*! the id of the t.38 gateway framehook for this channel */
 	int gateway_id;
 	/*! the timeout for this gateway in seconds */
diff --git a/res/res_fax.c b/res/res_fax.c
index cfe3dd10d..b5e5411ee 100644
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -225,6 +225,9 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 					<enum name="statusstr">
 						<para>R/O Verbose Result Status of the FAX transmission.</para>
 					</enum>
+					<enum name="t38timeout">
+						<para>R/W The timeout used for T.38 negotiation.</para>
+					</enum>
 				</enumlist>
 			</parameter>
 		</syntax>
@@ -521,6 +524,7 @@ static AST_RWLIST_HEAD_STATIC(faxmodules, fax_module);
 #define RES_FAX_MAXRATE 14400
 #define RES_FAX_STATUSEVENTS 0
 #define RES_FAX_MODEM (AST_FAX_MODEM_V17 | AST_FAX_MODEM_V27 | AST_FAX_MODEM_V29)
+#define RES_FAX_T38TIMEOUT 5000
 
 struct fax_options {
 	enum ast_fax_modems modems;
@@ -528,6 +532,7 @@ struct fax_options {
 	uint32_t ecm:1;
 	unsigned int minrate;
 	unsigned int maxrate;
+	unsigned int t38timeout;
 };
 
 static struct fax_options general_options;
@@ -538,6 +543,7 @@ static const struct fax_options default_options = {
 	.statusevents = RES_FAX_STATUSEVENTS,
 	.modems = RES_FAX_MODEM,
 	.ecm = AST_FAX_OPTFLAG_TRUE,
+	.t38timeout = RES_FAX_T38TIMEOUT,
 };
 
 AST_RWLOCK_DEFINE_STATIC(options_lock);
@@ -713,6 +719,7 @@ static struct ast_fax_session_details *session_details_new(void)
 	d->modems = options.modems;
 	d->minrate = options.minrate;
 	d->maxrate = options.maxrate;
+	d->t38timeout = options.t38timeout;
 	d->gateway_id = -1;
 	d->faxdetect_id = -1;
 	d->gateway_timeout = 0;
@@ -1716,7 +1723,10 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
 					break;
 				}
 				if (t38negotiated && !was_t38) {
-					fax->tech->switch_to_t38(fax);
+					if (fax->tech->switch_to_t38(fax)) {
+						GENERIC_FAX_EXEC_ERROR(fax, chan, "UNKNOWN", "T.38 switch failed");
+						break;
+					}
 					details->caps &= ~AST_FAX_TECH_AUDIO;
 					expected_frametype = AST_FRAME_MODEM;
 					expected_framesubclass.integer = AST_MODEM_T38;
@@ -1904,8 +1914,8 @@ static int receivefax_t38_init(struct ast_channel *chan, struct ast_fax_session_
 	/* request T.38 */
 	ast_debug(1, "Negotiating T.38 for receive on %s\n", ast_channel_name(chan));
 
-	/* wait up to five seconds for negotiation to complete */
-	timeout_ms = 5000;
+	/* wait for negotiation to complete */
+	timeout_ms = details->t38timeout;
 
 	/* set parameters based on the session's parameters */
 	t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
@@ -3923,6 +3933,7 @@ static char *cli_fax_show_settings(struct ast_cli_entry *e, int cmd, struct ast_
 	ast_cli(a->fd, "\tMaximum Bit Rate: %u\n", options.maxrate);
 	ast_fax_modem_to_str(options.modems, modems, sizeof(modems));
 	ast_cli(a->fd, "\tModem Modulations Allowed: %s\n", modems);
+	ast_cli(a->fd, "\tT.38 Negotiation Timeout: %u\n", options.t38timeout);
 	ast_cli(a->fd, "\n\nFAX Technology Modules:\n\n");
 	AST_RWLIST_RDLOCK(&faxmodules);
 	AST_RWLIST_TRAVERSE(&faxmodules, fax, list) {
@@ -4234,6 +4245,23 @@ static void get_general_options(struct fax_options *options)
 	ast_rwlock_unlock(&options_lock);
 }
 
+static int set_t38timeout(const char *value, unsigned int *t38timeout)
+{
+	unsigned int timeout;
+
+	if (sscanf(value, "%u", &timeout) != 1) {
+		ast_log(LOG_ERROR, "Unable to get timeout from '%s'\n", value);
+		return -1;
+	} else if (timeout) {
+		*t38timeout = timeout;
+	} else {
+		ast_log(LOG_ERROR, "T.38 negotiation timeout must be non-zero\n");
+		return -1;
+	}
+
+	return 0;
+}
+
 /*! \brief configure res_fax */
 static int set_config(int reload)
 {
@@ -4303,6 +4331,11 @@ static int set_config(int reload)
 		} else if ((!strcasecmp(v->name, "modem")) || (!strcasecmp(v->name, "modems"))) {
 			options.modems = 0;
 			update_modem_bits(&options.modems, v->value);
+		} else if (!strcasecmp(v->name, "t38timeout")) {
+			if (set_t38timeout(v->value, &options.t38timeout)) {
+				res = -1;
+				goto end;
+			}
 		}
 	}
 
@@ -4395,6 +4428,8 @@ static int acf_faxopt_read(struct ast_channel *chan, const char *cmd, char *data
 		ast_copy_string(buf, details->resultstr, len);
 	} else if ((!strcasecmp(data, "modem")) || (!strcasecmp(data, "modems"))) {
 		ast_fax_modem_to_str(details->modems, buf, len);
+	} else if (!strcasecmp(data, "t38timeout")) {
+		snprintf(buf, len, "%u", details->t38timeout);
 	} else {
 		ast_log(LOG_WARNING, "channel '%s' can't read FAXOPT(%s) because it is unhandled!\n", ast_channel_name(chan), data);
 		res = -1;
@@ -4521,6 +4556,10 @@ static int acf_faxopt_write(struct ast_channel *chan, const char *cmd, char *dat
 		if (!details->minrate) {
 			details->minrate = ast_fax_minrate();
 		}
+	} else if (!strcasecmp(data, "t38timeout")) {
+		if (set_t38timeout(value, &details->t38timeout)) {
+			res = -1;
+		}
 	} else if ((!strcasecmp(data, "modem")) || (!strcasecmp(data, "modems"))) {
 		update_modem_bits(&details->modems, value);
 	} else {